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April 2
Classical Physics
Greetings, Wikipedians!
I am now in my late 20s and recently an old fascination of mine has started bubbling up. I studied mathematics at the univeristy for a while (although I eventually gave it up and studied law instead) and I consider myself fairly competent in stuff like multi-variable calculus (even though I can't possibly call myself an expert). I have recently found my love for equations have started to come back to me. Everyone has to have a hobby, right? Anyway, specifically I've been fascinated with classical physics, i can spend a good chunk of a weekend (it annyos the hell out of my fianceé) studying things like this.
I never did study physics beyond high school, but I wish to pick it up again. Can anyone recommend a good book on classical physics for me? As I said, I'm fairly competent in advanced calculus, so it doesn't have to be a beginners pop-science type of a thing, but perhaps not too advanced either. I'm tempted just to pick up an annotated version of Newton's Principia, but as I understand, it's fairly archaic in it's mathematics and also fairly dense. Any recommendations?
Cheers!
Oscar
- Young's University Physics, or Benson's book by the same name seem popular to me. Both are introductory-level university texts that cover the basics of the whole field and are mostly classical, except for the obligatory chapter introducing the basics of quantum stuff. Neither of them require much more than some calculus skills. --BluePlatypus 03:28, 2 April 2006 (UTC)
- How about The Feynman Lectures on Physics? —Keenan Pepper 03:32, 2 April 2006 (UTC)
- I echo the Feynman lectures - they cover an incredibly broad range of topics, and are very well written. Admittedly, the maths doesn't get an awful lot more complex than second-year calculus, but I don't think it needs to be, either, if you're just starting out. — QuantumEleven | (talk) 09:40, 2 April 2006 (UTC)
- I recommend you give your fiancee a massage while you listen to the Feynman Lectures on tape. GangofOne 07:36, 2 April 2006 (UTC)
- Depending on your circumstances, H L Mencken's comment on physics may or may not be relevant to you and your fiancé: "It is now quite lawful for a Catholic woman to avoid pregancy by a resort to mathematics, though she is still forbidden to resort to physics and chemistry". :--) JackofOz 08:37, 2 April 2006 (UTC)
- It's not clear how the mathematical contraception works, (maybe he means the "rhythm method"?), but what I was getting at is you'll have a better life if you can get your spouse involved in your hobbies, maybe she'll enjoy the tapes so much she'll become intersested in classical physics, and more specifically, classical physiques. --GangofOne 07:47, 4 April 2006 (UTC)
- Depending on your circumstances, H L Mencken's comment on physics may or may not be relevant to you and your fiancé: "It is now quite lawful for a Catholic woman to avoid pregancy by a resort to mathematics, though she is still forbidden to resort to physics and chemistry". :--) JackofOz 08:37, 2 April 2006 (UTC)
- On a slightly separate note (I can't really recommend a good physics book, unless you're into Atmospheric Dynamics, in which case I'd recommend An Introduction to Dynamic Meteorology by J.R. Holton), have you considered becoming a Wikipedian yourself? We always need eager, well-rounded editors, and believe me when I tell you that the experience allows you to learn all sorts of interesting and eclectic information. EWS23 | (Leave me a message!) 08:43, 2 April 2006 (UTC)
Graphics Card/NIC combo in Fedora Core 4
I have a Cirrus Logic GD 5446 graphics card with built-in NIC. Although the graphic card part is detected and works on my Fedora Core 4 system, the network card is not recognised. When I plug in an ethernet cable connected to my modem, the green light (connection) comes on and the amber light (activity) flashes but according to Hardware Browser, it's doesn't come under 'Network devices'. Would installing a driver resolve this issue? There's one here but it doesn't specify an operating system. --Username132 (talk) 01:15, 2 April 2006 (UTC)
Is KDE installed?
It typed "yum install KDE" at the terminal in Fedora Core 4 but it didn't seem to be installing anything.
Here's how it went down;
[root@localhost numlockx-1.1]# yum install kde Setting up Install Process Setting up repositories updates-released 100% |=========================| 951 B 00:00 extras 100% |=========================| 1.1 kB 00:00 http://ftp.chg.ru/pub/Linux/fedora/core/4/i386/os/repodata/repomd.xml: [Errno 4] IOError: HTTP Error 404: Transfer-Encoding: chunked Date: Sun, 02 Apr 2006 00:46:26 GMT Content-Type: text/html; charset=iso-8859-1 Server: Apache/1.3.33 (Unix) Trying other mirror. base 100% |=========================| 1.1 kB 00:00 Reading repository metadata in from local files Parsing package install arguments No Match for argument: kde Nothing to do [root@localhost numlockx-1.1]# start kde -bash: start: command not found [root@localhost numlockx-1.1]# kde -bash: kde: command not found [root@localhost numlockx-1.1]# run kde -bash: run: command not found [root@localhost numlockx-1.1]# yum install kde Setting up Install Process Setting up repositories Reading repository metadata in from local files Parsing package install arguments No Match for argument: kde Nothing to do
How do I know if KDE is already installed? And if it is, how do I start it? If I started KDE, would it close down Gnome? My computer couldn't run two GUIs at the same time very well.
--Username132 (talk) 01:20, 2 April 2006 (UTC)
- Computers aren't smart enough to guess at what you want. Try "yum list | grep kde" to see what packages have "kde" in the name. Then, install the whole package name, such as "yum install kdebase". As you can see from the message you received, there is no packaged names "kde". --Kainaw (talk) 01:34, 2 April 2006 (UTC)
- I see, thanks :). It could have been more clear about things... how come "yum list | grep opera" doesn't produce any results, when I know "yum install opera" does something (I think Opera web browser). --Username132 (talk) 04:57, 2 April 2006 (UTC)
- Unless you've added repositories to the generic Fedora repositories, Opera is not included. Fedora only includes free, open-source programs. Opera is free now, but used to require payment (yes, there was a free preview version, but that isn't the point). Also, Opera is not open-source. Finally, depending on your version of grep, you may want to include the "-i" option to turn of case sensitivity, such as "yum list | grep -i SDL" --Kainaw (talk) 20:23, 2 April 2006 (UTC)
- Ah, thanks for the tip! --Username132 (talk) 00:33, 4 April 2006 (UTC)
chloroform
What does chloroform react with to make someone unconscious?
Scientific how does it?
- Chloroform is a general anaesthetic. According to the Wikipedia article on general anaesthetic:
- "It is now known that general anaesthetics act on the central nervous system by modifying the electrical activity of neurons at a molecular level by modifying the function of ion channels. This may occur by anaesthetic molecules binding directly to ion channels or by their disrupting the function of molecules that maintain ion channels." --Bowlhover 05:07, 2 April 2006 (UTC)
- Here's an article: http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1328629
- Chloroform increases the permeability of the cell membrane to ions, which makes it harder to build up an action potential. —Keenan Pepper 14:19, 2 April 2006 (UTC)
Chloroform cannot be a true general anaesthetic, becuase if it were, it would paralyze the all the body's involuntary autonomous systems. For example, when a true general anaesthetic is used, the lungs no longer function and a breathing machine is required to keep the patient alive. From what I understand of chloroform, the subject may be "knocked out" but he or she is still able to breath...etc...Loomis51 21:44, 6 April 2006 (UTC)
Paint thinner chemical
I'm having trouble finding out the name of a chemical that is in some paint thinners and it becomes carbon monoxide when inhaled. Any guesses? KeeganB
- When fuels are burnt with insufficient amounts of oxygen, incomplete combustion can occur. Instead of the normal CO2, some CO is also produced. Some paint thinners contain (surprise!) isopropyl alcohol, also known as isopropanol, which can decompose and release CO gas. Isopropyl 05:46, 2 April 2006 (UTC)
I forgot to mention that this chemical is metabolized by the body and it becomes carbon monoxide because of the metabolization. KeeganB
- Are you sure it's carbon monoxide that it gets metabolized to? Toluene, the chemical that gives paint thinner its characteristic smell, is rather toxic; it breaks down into epoxide radicals in your body. Other than that, I have no idea what the chemical could be. Perhaps you could take a look at the packaging and look up the chemicals listed in the warnings? Isopropyl 06:29, 2 April 2006 (UTC)
- Paint thinners are generally a mixture of Hexanes (Toluene), Isopropyl, or Acetone. Really depending on the type of paint thinner you are purchasing. I don't know of any of these that would be metabolised by the body readily, more likely you're going to exhale the fumes. If any it would be isopropyl, and it's still not advisable to inhale or ingest it. This is why you wear a face mask and use paint thinners in well ventilated areas.--Tollwutig 17:53, 3 April 2006 (UTC)
SSH, PGP and CACert
I have three key-pairs: one for SSH, one for PGP and a "client certificate" from CACert. Don't all these serve the same purpose? Is it possible to use the same key-pair for all three? —Masatran 06:52, 2 April 2006 (UTC)
- Typically, no. These (as far as I know) use different encryption algorithms, and even if you could have, say, the same private key for all of them, the public keys would differ. But why do you care? You'll certainly never interact with your own SSH key (
sshdis all that touches it), and a certificate is just a statement made and signed by the certificate authority that identifies you. Neither of those will involve you very often.
- To answer your other question: no, these are for different purposes. The SSH key is used to prove to SSH clients that your server is the same server they've used before and not an impostor. The PGP key is used by others to make messages readable only by you and by you to prove that you wrote something. The certificate is again some identification of you (perhaps your real name and a ___domain name of yours) signed by someone that you expect others to recognize and trust to make such identifications. --Tardis 18:47, 5 April 2006 (UTC)
- There's no reason why, in a theoretical sense, you couldn't use a single public-private key pair for different applications. It's a question of the software supporting it. For example, I seem to recall that some SSH implementations allow the use of X.509 certs, and you can extend OpenSSH to allow the use of PGP keys[1]. — Matt Crypto 19:26, 5 April 2006 (UTC)
- OK, after some research, I see that as least SSH and PGP are compatible through RSA and DSA. I thought PGP's encryption was some other variety. But I can't imagine that PGP could work together with X.509, unless what the certificate was for was the public key...? --Tardis 21:19, 5 April 2006 (UTC)
- X.509 certificates certify that a public key belongs to some entity, so there's no reason, in principle, why an OpenPGP application couldn't use a key from an X.509 certificate. It seems that PGPi supports X.509 certs[2], for example. For encrypting and/or signing messages, a key is just a key, and the differences are superficial (file formats etc). The big issue is the PKI, i.e., how you can reliably find out someone's public key without being spoofed: web of trust (OpenPGP) vs a CA (X.509) vs, er, ad hoc verification (or none!) (SSH). — Matt Crypto 12:45, 7 April 2006 (UTC)
- OK, after some research, I see that as least SSH and PGP are compatible through RSA and DSA. I thought PGP's encryption was some other variety. But I can't imagine that PGP could work together with X.509, unless what the certificate was for was the public key...? --Tardis 21:19, 5 April 2006 (UTC)
Satellites
Can you see Satellites in night with nakes eyes from the ground?
- Yes! But I've never seen one. This link tells you how to do it, as does this one. And this one tells you about the hobby. Hope this helps. Kilo-Lima|(talk) 11:25, 2 April 2006 (UTC)
- Sure. I see them often, though. They're small and star-like, except they move at a constant speed across the sky. ☢ Ҡi∊ff⌇↯ 19:51, 2 April 2006 (UTC)
- Iiridium flares, which are generated by the Iridium satellites' main mission antennas, are extremely bright (the brightest flares can reach magnitude -8, 28 times Venus's maximum brightness). Heavens Above provides predictions for iridum flares and HST/Envisat/ISS passes. Be sure to enter the latitude, longitude, and elevation of your house, not your city--the coordinates have to be very accurate. --Bowlhover 20:16, 2 April 2006 (UTC)
- They're not particularly difficult to spot - look up just after sunset or just before sunrise (the satellite above you needs to be illuminated while you need to be in darkness). If you see a star moving across the sky rapidly without blinking (if it's blinking, it's probably an airplane), you've just spotted a satellite. When I say "rapid" I don't mean rapid like a meteor (gone in about a second), but fast enough that it's easy to see it moving - it takes about a minute or two to cross the entire sky. Happy stargazing! — QuantumEleven | (talk) 21:31, 2 April 2006 (UTC)
- The ISS is particularly bright - about as bright as one of the brighter planets (say, Jupiter) I second Bowlhover's comment about Heaven's Above - it;'s a very good website if you want to find out when bright satellites will be overhead. Grutness...wha? 06:58, 3 April 2006 (UTC)
- You didn't exclude natural satellites, so I would add that the Moon is occasionally visible. StuRat 19:26, 3 April 2006 (UTC)
- A satellite in the sky often looks like an aircraft since they have a similar apparent angular motion. A commercial jet might fly 10 km high (about 30,000 feet) and travel at a speed of 1000 km per hour (about 600 mph, or 0.3 km/s). A low Earth orbit (LEO) satellite is about 30 times higher and travels about 30 times faster, so the motion looks almost the same (300 km altitude, 8 km/s). For an aircraft, you are usually seeing the lights - if it blinks, you know it is an aircraft. But you can only see a spacecraft when it is still in sunlight are you are in shadow, after sunset or before sunrise. Sometimes you can see the spacecraft enter the Earth's shadow, turning red and then fading quickly. elee 16:50, 6 April 2006 (UTC)
why is thepiratebay.org still up?
I would have thought that the RIAA/MPAA/(insert name here) would have shut it down ages ago. After all, how much closer to a blatant copyvio can you get?--Frenchman113 16:05, 2 April 2006 (UTC)
- Well, IANAL, but they do have a point that "Only torrent files are saved at the server. That means no copyrighted and/or illegal material are stored by us...". Also, it's possible the servers are in a country where the RIAA and MPAA have no power. Anyone know where the servers actually are? —Keenan Pepper 16:37, 2 April 2006 (UTC)
whois -H thepiratebay.orgturns up registration in Stockholm, Sweden. Isopropyl 16:46, 2 April 2006 (UTC)
- Because they're not violating copyright law. They're not actually distributing the copyrighted material themselves. Merely linking to it isn't illegal. Sweden isn't the only country where this is probably the case, so the more pertinent question is perhaps why the Swedes are less prone to fold to empty legal threats? --BluePlatypus 17:27, 2 April 2006 (UTC)
- The Pirate Bay are frequently contacted by individuals and organizations requesting removal of copyrighted materials from their site. They (and their lawyers) find this extremely humorous, and post the correspondence on their site at the URI http://thepiratebay.org/legal (I think that's the right address). --WhiteDragon 19:20, 4 April 2006 (UTC)
- Almost - it's http://thepiratebay.org/legal.php. -- Marcika 21:48, 5 April 2006 (UTC)
- The Pirate Bay are frequently contacted by individuals and organizations requesting removal of copyrighted materials from their site. They (and their lawyers) find this extremely humorous, and post the correspondence on their site at the URI http://thepiratebay.org/legal (I think that's the right address). --WhiteDragon 19:20, 4 April 2006 (UTC)
Why do voltage regulators come as modules?
I was wondering why the voltage regulator on a server processor board comes as a module (VRM) instead of being soldered in place like I imagine it is on my PC motherboard. Are they prone to failure? --Username132 (talk) 14:31, 2 April 2006 (UTC)
- The answer is at voltage regulator module. --Heron 18:52, 2 April 2006 (UTC)
- So if it comes as a separate module, it must be fixed to a specific voltage? --Username132 (talk) 22:25, 2 April 2006 (UTC)
- It has a lot to do with costs. With a $5k-$30k server you're more likely to keep it a long time and upgrade processors instead of replacing the unit. If you are in the IT industry you know processor generations are about 6 months to 1 year. With a PC a system board usually only costs between $100-$300, while a server it can cost between $1000-$3000 just for the system board alone.
Now say you have a server you wish to upgrade the processors. Which is cheaper, to replace a VRM or an entire system board?--Tollwutig 16:23, 3 April 2006 (UTC)
Topic Suggestions
I need some topic ideas for my IB Extended Essay maybe you guys could help. The subject I want to do is in computer science. I have some knowledge of neural networks, genetic programing (algorithms), economics (could be relevant? modeling?) and cryptography (along with misc. computing knowledge). The essay must have an original thesis that sets out to prove somthing non-trivial (someone else is doing stuff involving computational ecomplexity). Any suggestions? (By the way: the project cannot be writing a program to do somthing (although that could be part of the essay)). Leonardo 16:17, 2 April 2006 (UTC)
Define the least intelligent worm that when let loose on the internet increases its intelligence without limit, given enough time and no serious eradication effort. The minimum computational skill set for unbounded automated learning. WAS 4.250 17:52, 2 April 2006 (UTC)
- How about building elementary logic gates with cells via DNA transcription? That's what I'm studying right now, and it's kind of interesting, I guess. Isopropyl 17:56, 2 April 2006 (UTC)
- An economics topic which interests me is ideal firm size. A program which accepts firm size and growth rates as input could calculate the ideal firm size for the maximum growth rate in several industries, study how the ideal firm size has changed in each industry over time, etc. Note that you would need to include companies which have declared bankruptcy, or you would introduce bias towards small firms. StuRat 19:16, 3 April 2006 (UTC)
- Hmmm, I think that's too economic and not computer science enough. As to isopropyl, that's an idea, but it requires more biology than I know (I guess I could try to pick it up). And as to WAS 4.250...Cool idea conceptually, but yeah that's beyond me. I wouldn't even know where to begin. I might do something with intelligent malware though. Hm...cryptovirology? Anyone have any topic ideas involving that? Leonardo 21:11, 4 April 2006 (UTC)
- An economics topic which interests me is ideal firm size. A program which accepts firm size and growth rates as input could calculate the ideal firm size for the maximum growth rate in several industries, study how the ideal firm size has changed in each industry over time, etc. Note that you would need to include companies which have declared bankruptcy, or you would introduce bias towards small firms. StuRat 19:16, 3 April 2006 (UTC)
good largescale spyware removal utility? for free?
suggestions?--172.153.199.58 17:13, 2 April 2006 (UTC)
- What do you mean by "large scale"? If you're looking for enterprise quality software you'll have to pay for it. The most popular & most frequently recommended consumer freebee apps are LavaSoft's AdAware, Spybot, and HiJackThis. Using all three provides a rather comprehensive solution. You can download these or search for others at majorgeeks.com. Also, take a class on editing the Windows registry if you use Windows. There are a number of free registry utilities but be careful if you don't know what you're doing. Registry errors can make your system nonfunctional. Ande B 22:56, 2 April 2006 (UTC)
- Adaware is a good antispyware, but what do you mean by largescale?--Frenchman113 22:59, 2 April 2006 (UTC)
- A good large scale spyware removal tool? None really get rid of all spyware as often you need to be in Safe Mode and do registry edits to get rid of the worst offenders. The best means is to prevent spyware by setting your firewall to block all traffic on port 80. Its the most effective preventative measure I have found.--Tollwutig 16:16, 3 April 2006 (UTC)
- Blocking all ports or physically disconnecting your computer from the network works even better. --Optichan 16:33, 4 April 2006 (UTC)
Integer precision
- In C++, what is the most portable way to get an integer type guaranteed to have at least n bits of precision?
- Is there any portable way to get an integer type that not only has exactly n bits of precision, but also wraps around modulo 2n on overflow? For example, an 8-bit type in which 100 + 200 == 44. —Keenan Pepper 17:14, 2 April 2006 (UTC)
- No. You will want to use sizeof to detect the size of the short an long types and then manipulate them as necessary. With 64-bit systems becoming popular, this is a real problem right now. --Kainaw (talk) 22:22, 2 April 2006 (UTC)
- For number 1, you could try GMP, which is fairly portable (certainly *nix and Windows) and has a C++ interface (it is C internally.) For number 2, that is what happens with the built-in integer types in C and C++, the problem is that the sizes of the various types (char, short int, int, long int) are not defined in the specs. -- AJR | Talk 22:36, 2 April 2006 (UTC)
- For small values of n, is it possible to use
- typedef struct { int eightBit : 8; } number;
- number a.eightBit = 257; // Stores 1 in a.eightBit Ojw 23:11, 2 April 2006 (UTC)
Okay, I didn't think #2 was possible. For #1, I was looking for something along the lines of stdint.h for C. I notice there's no <cstdint> in the standard C++ library... —Keenan Pepper 23:35, 2 April 2006 (UTC)
- <cstdint> will most likely appear in the next C++ standard update, but because of the glacial pace of the international standards process, you might have to do with <boost/cstdint.hpp> available at [[3]]. If you can limit yourself to Unix, the Single Unix Specification defines a similar <inttypes.h>, not to be confused with the C99 inttypes.h. 84.239.128.9 19:02, 3 April 2006 (UTC)
electronic marketplace
describe an electronic marketplace in which disc technology combines with the internet to provide information and services to consumers
- Do your own homework. --Bowlhover 19:27, 2 April 2006 (UTC)
- Pornography!! Tzarius 09:11, 3 April 2006 (UTC)
- Yeah I'd say pr0n is the major use of this.. also this stinks of a homework question.--Tollwutig 16:12, 3 April 2006 (UTC)
Handwashing
A friend told me that most soaps advertised as anti-bacterial actually can increase the amount of bacteria present on the hands. Is this true and why would this occur?
AO24 21:52, 2 April 2006 (UTC)
- Most likely, he was referring to the growth in super-resistant bacteria. By killing common bacteria quickly, only the resistant bacteria remains. Over time, the resistant bacteria will evolve into super-resistant bacteria that is completely immune to our common household anti-bacterial soaps, cleaners, and air sprays. All-in-all, the "anti-bacterial" craze can be seen as doing more harm than good. Not all bacteria will harm you. Many forms of bacteria help you. Killing the good ones is not a healthy thing to do. Making the bad ones resistant is not a healthy thing to do. The next time you see something that kills 99.99% of all bacteria, remember that it may only leave that 0.01% that can actually cause you harm. --Kainaw (talk) 22:11, 2 April 2006 (UTC)
- (After edit conflict)Your friend has, I think, gotten something confused, but there's a kernel of truth behind it. It's not that washing with antibacterial soap leads to more bacteria, but rather that it can lead to production of superbugs --bacteria that are resistant to normal treatment, and also kills off the helpful bacteria. It works like this: you wash with a soap containing a particular antibacterial agent. It kills 99% of the bacteria that are susceptible to it. The one percent then breed back to high numbers, but because they are the ones who survived the last treatment, they naturally have some defense to the agent you used which they pass on to their progeny. You use the same soap with the same agent again. This time, because the generation that are left are more resistant, only 70% die. They breed back to level. This cycle continues until you have bacteria that are very resistent to the agent in the soap. This is how evolution works, and is the same reason we have developed so many antibiotic resistant strains of microbes (which has been greatly increased by blanket prescribing of antibiotics where it is not necessary, as well as people's tendency to not take the full antibiotic series). --Fuhghettaboutit 22:12, 2 April 2006 (UTC)
- Not necessarily. If the "antibacterial" agent is just a disinfectant and not an antibiotic, then this shouldn't breed antibiotic resistance. People who use antibacterial soap might not wash their hands as carefully, so they don't end up killing as much bacteria on their hands as someone doing a proper hand-wash with regular detergent soap. - Cybergoth 02:13, 3 April 2006 (UTC)
- Even disinfectants can lead to resistant bacteria. Bacteria can adapt to chemicals in the environment as well as antibiotics. --Tollwutig 16:10, 3 April 2006 (UTC)
Killing off the good bacteria (which control the bad bacteria) could allow the bad bacteria to spread uncontrolled. I'm not aware of this being a problem on hands, but medicated douches can cause this very problem in the female reproductive tract. StuRat 19:05, 3 April 2006 (UTC)
April 3
Computer Technology-Measurement of the Capacity of Hard Disk Drive 
Someone has just asked me about the capacity of my PC's hard disk drive.I have tried checking all manuals that were delivered with my PC but I could not find this information.Maybe it's because I do not know where to look for this information and also that I do not know how the capacity of a hard disk is measured.Internet research about my PC brought out this, "Storage :40/80/120/160/200/GB ATA/100 hard disk drive".This confused me even further.Is my answer found in any of the figures quoted above or I have to look elswhere?
- If you're on a Windows XP PC, click "Start" Then "My Computer" then "Local Disk (C:)" the details in the lower left will tell you the storage of your hard disk drive ("Total Size"). If you did your research right then that number will be around 40/80/120/160/200/GB. See Gigabyte for how the storage capacity of a hard disk is measured. -Snpoj 01:36, 3 April 2006 (UTC)
- If you're using Linux, run fdisk as superuser and type "p" when it asks you for a command. Also, try checking the sides of your computer. Some computers have general system information printed there. --Bowlhover 04:59, 3 April 2006 (UTC)
- If you don't have root privileges, try "df -h" though you may have to do some simple addition to get the answer. --Bth 09:26, 3 April 2006 (UTC)
- Note that "df -h" is only useful for finding out the disk size when:
- (a) There is no disk space that is not part of a partition, and
- (b) All of the partitions are mounted. --Bowlhover 04:21, 4 April 2006 (UTC)
- Note though that you can type fdisk -l to get information about the partitions without starting the fdisk program interactively. (There's a similar option to the DOS fdisk program, fdisk /status I think.) – b_jonas 14:18, 4 April 2006 (UTC)
just a note, 40/80/120/160/200/GB means 40 or 80 or 120 or 160 or 200 gigabytes. your computer could be near any of these values. if you are still having difficulty, ask your local 14 year old. good luck
- Another note, harddisk manufacturers use a different standard from most OS's to calculate size, and thus there will almost certainly not be a round number displayed. Manufacturer uses XX * 10^9 as a standard for gigabytes, while Windows uses XX * 2^30 for gigabyte. The first is about 6% smaller then the latter. SanderJK 09:30, 3 April 2006 (UTC)
UFO sightings
Yesterday and the day before yesterday, I spotted 3 UFOs. The first two were patches of dim, white light (by the way, there were thin clouds when I saw this), about 1 degree large, moving quickly across the sky. "Quickly", in this case, means "faster than the high-altitude airplanes that leave visible trails, about the speed of the airplanes that don't leave trails and whose blinking lights can be seen, but faster than satellites". The third UFO was very bright, certainly much brighter than the magnitude -5 iridium flare I saw, and it travelled from the triangle in Leo to the constellation Cancer in little less than a second. It simply vanished after reaching Cancer. (Note: I couldn't see any of Cancer's stars, but the bright Saturn marked its position).
Any ideas about what the three UFOs I saw were? Thanks. --Bowlhover 05:14, 3 April 2006 (UTC)
- The third one brings to mind a meteor, perhaps a sporadic Leonid. –Mysid 07:19, 3 April 2006 (UTC)
- If you don't know what it was, how do you know how big it was? And if you don't know how big it was, how do you estimate how fast it was? --BluePlatypus 13:39, 3 April 2006 (UTC)
- Also, the ufo guys used some device that kept photons for reaching his eye, so Bowlhover could estimate that they were farther. --DLL 18:57, 3 April 2006 (UTC)
- I don't know how big the UFOs were, or how fast they were moving. However, I do know how big they appeared to be, and how fast they appeared to move. Sorry for the confusion--when I said "faster than the high-altitude airplanes", I was refering to the apparent speed, not the absolute speed.
- I originally thought that the third UFO was a meteor, too. However, the Wikipedia article on meteors said that the British Astronomical Association defined fireballs as meteors that are magnitude -5 or brighter, implying that fireballs are rare. There was no meteor shower yesterday, I had been outside for only 3 hours when I saw the UFO, and the UFO was much brighter than magnitude -5. Could I really have been that lucky? --Bowlhover 19:43, 3 April 2006 (UTC)
- Yes. In any case, keep good records. If there were actually physical objects, then others may see them. If you don't keep records of exact time and position in the sky, etc, it's just hearsay. If there is an actual phenomenon, then over time correlations between various records will reveal a pattern. GangofOne 00:45, 4 April 2006 (UTC)
- I originally thought that the third UFO was a meteor, too. However, the Wikipedia article on meteors said that the British Astronomical Association defined fireballs as meteors that are magnitude -5 or brighter, implying that fireballs are rare. There was no meteor shower yesterday, I had been outside for only 3 hours when I saw the UFO, and the UFO was much brighter than magnitude -5. Could I really have been that lucky? --Bowlhover 19:43, 3 April 2006 (UTC)
- I agree, but whether I keep accurate records or not will not influence whether my claims are hearsay. They're hearsay no matter what. Also, I know that to many people, "UFO" is a synonym for "alien spacecraft". I don't think the UFOs I saw were alien spacecraft--they were simply objects I could not identify at the time (although I strongly suspected the third one to be a meteor--I still do). --Bowlhover 04:17, 4 April 2006 (UTC)
- In a legal sense, if you write observations down in a notebook at the time they occur, they will have more evidentiary status in a court of law or scientific dispute, as time passes, than if you say, 'in the beginning of March 2006 I saw some lights in the sky in an easterly direction', which is worthless. GangofOne 07:27, 4 April 2006 (UTC)
- I agree, but whether I keep accurate records or not will not influence whether my claims are hearsay. They're hearsay no matter what. Also, I know that to many people, "UFO" is a synonym for "alien spacecraft". I don't think the UFOs I saw were alien spacecraft--they were simply objects I could not identify at the time (although I strongly suspected the third one to be a meteor--I still do). --Bowlhover 04:17, 4 April 2006 (UTC)
- If the third object looked like a bright meteor to you, it seems likely that it was. According to the American Meteor Society FAQ, fireballs of magnitude -4 can be expected about once in every 20 hours of observing and magnitude -6 or better for every 200 hours. So maybe you DID just get lucky. It's hard to guess what the first two objects (patches of dim white light) were from the description alone. Is it possible that they could have been searchlights reflecting off the thin clouds that you mentioned were present? --DannyZ 07:14, 5 April 2006 (UTC)
Density of argon
Anyone got the density of solid argon at freezing point (84K IIRC) handy? -- Миборовский U|T|C|M|E|Chugoku Banzai! 05:36, 3 April 2006 (UTC)
- This page gives the density as 1636 kg/m^3, though doesn't state what temperature and pressure that's measured at. --Bth 07:16, 3 April 2006 (UTC)
- This has the most information I can find and gives the density of 535.6 kg/m^3 at Argon's critical point of -122.3 C Nothing I can find shows much information about Argon's solid form of -199.3C Bth reported the Density of the Gas at 0C. --Tollwutig 16:05, 3 April 2006 (UTC)
- I used to have density charts for all the phases of the various chemical elements. But alas, now they argon. StuRat 07:49, 4 April 2006 (UTC)
- That's very unhelpful of that page to give it as the "solid" density, then. Thanks for the correction, though. --Bth 08:54, 4 April 2006 (UTC)
- Kaye and Laby to the rescue! (ish) They give the density as 1656 kg/m^3 at 40K (and standard pressure if I'm reading them right, so it should be in the solid form), but that seems suspiciously similar to the gas-at-zero-celsius if Tollwutig is right. They do give the melting point of 84K that Miborovsky remembered. --Bth 12:41, 5 April 2006 (UTC)
Synesthesia/Light Organ
Hello, I recently read an article, but I cannot find it again. It pertained in some way to synaesthesia, among other things. It mentioned a composer, possibly Scriabin, and how he used a light organ, as well as how he experimented on having smells waft through the audience. The article also stated that he wanted his magnum opus to be performed at the base of a mountain. I don't believe synthesthia was the main focus of the article. It had something to do with sound I think, and I remember there were a few charts on it. There was perhaps some kind of system, and its inventor had a name that was a double entendre, its other meaning being a part of the brain, I believe. Is there an author out there who knows what I speak of? Thank you, KeeserSilver
Words losing all meaning
Why is that when you repeat a word several times it eventually "loses all meaning", as in the word appears wierd and you see it differently ts hard to describe buti hope someone knows what i mean. Thanks Kingstonjr 14:49, 3 April 2006 (UTC)
- I know what you mean (try typing or writing a word forty or fifty times, or staring at a page of a book with the same word repeated over and over on the whole page - I think this was done in Microserfs) - but I don't know if there's a word for it. I couldn't tell you the cause, either. Proto||type 15:31, 3 April 2006 (UTC)
- yea i know exactly what you mean, it is hard to explain i dont know what causes that though. modesty 16:22, 3 April 2006 (UTC)
Let me propose a theory: Our minds are designed to only notice new or changing things. For example, if you look at a scene, your attention will immediately be drawn to the moving object and will virtually ignore the rest. A repeated word gets the same treatment. You should keep this in mind and avoid sentences like "I excitedly saw how excited they were due to the excitement of the current situation and the exciting day in general". A better sentence would be "I was happy when I saw how glad they were due the excitement of the current situation and the interesting day in general". StuRat 18:41, 3 April 2006 (UTC)
- I found an interesting hypothesis on some random web site regarding this: Any word in any lexicon will start to sound funny if you repeat it aloud enough times. That's because after hearing a word x times, your mind starts to realize that there's no context associated with it, and therefore it lacks the meaning(s) it would have under normal circumstances. Your mind starts to analyze the sounds that make up the word, and the actions that are being taken by your vocal cords, tongue, teeth and nasal passages to create the sounds. Makes sense, but who knows? – ClockworkSoul 00:59, 4 April 2006 (UTC)
- That "dynamic change" theory explains a lot of things, such as why we feel dizzy long after we (and the little doodad in the inner ear) have stopped spinning, and various visual illusions (especially the one with the ring of pink dots and the phantom green dot). Tzarius 08:29, 4 April 2006 (UTC)
I looked for some scientific reasearch on this a while back, and I found that the term for the phenomena is "auditory habituation", where the repeated words undergo a "verbal transformation", so you may want to use those as search keywords if you plan to do more reasearch on the subject. You could also have a look at this paper from APA Online, however you have to pay to view it unless you college/school library has a subscription. Hope this helps. --Aramգուտանգ 05:49, 5 April 2006 (UTC)
Ancient puzzle
When I was a kid I read the following (paraphrased) puzzle in a book:
A man wants to cross a bridge that can support 10 lbs. more than he weighs. He is carrying (3) balls that weigh 5 lbs. each. How can he cross the bridge without collapsing it?
The answer was to juggle the balls as he crosses the bridge. Ostensibly he would be carrying only (2) balls at a time, as one would always be in the air. However, the force necessary to toss the third ball into the air would create additional downward force that I believe would be enough to collapse the bridge. Does it matter to the bridge that the balls are being juggled?
- hrmm, you also have to think when he catches a five pound ball (5 pound balls seem like a lot to juggle btw) its going to produce a force stronger than 5 pounds from it falling a distance of 1-2 feet or so. i think for this to even consider to be workable hes going to have to have a maximum of 1 ball on him at any given time modesty 16:26, 3 April 2006 (UTC)
- Why doesn't he just cross the bridge with two balls, go back and get the third one? User:Zoe|(talk) 16:33, 3 April 2006 (UTC)
- Because monkeys will steal the third ball if he leaves it behind?
- lol yea, and really if the bridge can only support EXACTLY 10 pounds over his weight, will it break if he steps too hard? the whole question is dumb i dont think weight limits work that way modesty 18:08, 3 April 2006 (UTC)
1) Kill all the monkeys on this side of the bridge.
2) Cross the bridge without your balls.
3) Kill all the monkeys on the other side of the bridge.
4) Go back over the bridge.
5) Toss your balls over.
6) Cross the bridge yourself and reward yourself with a nice monkey brain stew. StuRat 18:30, 3 April 2006 (UTC)
- Think of holding a single ball as accelating it at 1 g. To throw the ball the max acceleration w/o exceeding the limit of the bridge would be 2g. Say you take 1 second to throw the ball. That's 2g of acceleration for 1s, 1s for the ball to reach it's apex, 1s to fall back to your hand and 1s to decelerate the ball at 2g. Two seconds required to throw and catch gains you two seconds of flight time for the ball.
- To get across, raise the side of the bridge you are on, using rocks, dead monkeys etc., then roll across (see inclined plane.) EricR 20:03, 3 April 2006 (UTC)
- So essentially its Myth:busted on the fact that you cannot gain any legitmate force-over-time by juggling (other than the delight of onlookers). I agree that the premise is preposterous in a real world setting amyway since forces from footsteps, wind, evil monkeys, etc would combine and create a great likelihood that the bridge will fall regardless of your juggling antics. --Jmeden2000 20:36, 3 April 2006 (UTC)
- Free body diagram. Peter Grey 06:18, 7 April 2006 (UTC)
dual booting linux/windows
hey i currently have windows xp running on a 60 gig hd. i want to install linux dual boot for a number of reasons. however i read that i would have to partition this hard drive and split it between the two OS. i have been meaning to get a new hard drive anyway for additional storage and to not risk losing my old hard drive data in the process. so my questions are: | 1. if i do get a second hard drive thats say 120 gigs or so, can i give linux 60 gigs of that and windows another 60? | 2. how would i go about doing that- the red hat site lists a program called partitioner or something | 3. will i be able to access files(mp3s) stored on my current hard drive(which i guess has a windows file management system) in linux? | 4. lastly if you recently bought or know a good quality quiet hard drive that holds 100-200 gigs for an ok price give me a link:D cheers- modesty 16:32, 3 April 2006 (UTC)
- Yes.
- The installer for your chosen Linux distribution will let you partition your hard drive. By only allocating 60GB in that program, you can then choose to use the remaining space to create another partition in Windows using Disk Management under Control Panel -> Administrative utilities (I think that's the English name for it).
- Yes, but you may need to upgrade your Linux kernel to be able to read NTFS partitions. This varies between distributions, and *may* require you to re-compile a new kernel yourself. If you also want to access the Linux disk from Windows, you should use ext2 or ext3 for your Linux partition and install a file system driver for XP (such as Ext2fsd). Then, you can assign a drive letter using Disk Management. --Pidgeot (t) (c) (e) 16:55, 3 April 2006 (UTC)
- Don't tell newbies to compile their own kernels. That's just cruel.
- I didn't say he should compile a new kernel, I said that depending on the distribution he chooses, that may end up being necessary. With that knowledge, he can go look for one that DOES support it without recompiling. --Pidgeot (t) (c) (e) 18:07, 3 April 2006 (UTC)
- 1. You could do that, but I don't see why you would want to. Personally, I would format most of the new disk as something both Windows and Linux can access, like FAT.
- 3. It depends which "windows file management system" it is. If it's FAT, Linux will have no problem with it. If it's NTFS, you might have some problems. I know there's a native Linux driver for NTFS that can read files, but I think the write support is still buggy. Reverse engineering is hard.
- 4. I bought a Seagate 120G for like $50 which has been running fine for a good while now. —Keenan Pepper 17:04, 3 April 2006 (UTC)
- As a side note always install Windows first and Linux second, as the Windows installer is ALWAYS set to rewrite the boot sector of the disk. --Tollwutig 17:59, 3 April 2006 (UTC)
- thanks, i just got this computer in december and its a dell e510... dunno if its fat or nts (probably whichever is newer?) with xp media center edition, and im installing fedora core 5... this will be cool if it works out as easily as you both have made it sound... thanks again, fast replies 129.32.93.17 18:02, 3 April 2006 (UTC)
- XP uses NTFS by default unless you changed something during install. There are utilities for reading/writing NTFS under Linux, but they're all experimental and I wouldn't mess with it. Personally, I have a FAT32 partition that I use to store common files for use under both Windows and Linux, as they can both safely read/write this format. Isopropyl 18:09, 3 April 2006 (UTC)
- thanks, i just got this computer in december and its a dell e510... dunno if its fat or nts (probably whichever is newer?) with xp media center edition, and im installing fedora core 5... this will be cool if it works out as easily as you both have made it sound... thanks again, fast replies 129.32.93.17 18:02, 3 April 2006 (UTC)
- And there is no saying that you have to use just 2 partitions. You could split the drive into 3 Partitions. 30 GB for Windows XP install (NTFS), 30 GB for Fedora Core 5, and then a 60 GB FAT32 Partition for your Data. This way you won't have to compromise your Windows Security (not quite an Oxymoron)by using FAT on the OS. Really though if you move install your Programs into the Data Drive you can get by with a 10-15 GB partition for your OS installs. The advantage of this is you don't have to mount the other OS install partition, so you don't mess up something on the other OS install.--Tollwutig 18:47, 3 April 2006 (UTC)
- hrmm thx all seems pretty easy. i think the fedora 5 reads ntfs so i dont think file format will be an issue, just wondering how im going to go about splitting this up. i might just install linux to the hard drive i have now, give it 20 GB, and then get a nice 200gb hard drive and put fat32 on it... if anyone stills cares to answer, will there be any difficulties partioning t hsi hard drive seeing its already got about 35 gb of random crap (in ntfs) on it? if not ill just put linux on it tonight modesty 19:32, 3 April 2006 (UTC)
- Shouldn't have an issue as long as you can resize the current partition. Norton Partition Magic if you have it is great for this sort of thing, as you cannot change the system partition inside of Windows. If you can find a means to repartition outside of Windows it's fairly straight forward.--Tollwutig 19:48, 3 April 2006 (UTC)
- Piggybacking: is this FAT/NTFS thing the reason why on my previous machine I used to be able to modify my Windows 98 drive from within Linux, but on my newer computer with XP the whole of /mnt/windows/ is read only? --Bth 08:42, 4 April 2006 (UTC)
- Probably. It's hard to say for sure unless you provide the output of your fstab file. --Optichan 16:53, 4 April 2006 (UTC)
- Piggybacking: is this FAT/NTFS thing the reason why on my previous machine I used to be able to modify my Windows 98 drive from within Linux, but on my newer computer with XP the whole of /mnt/windows/ is read only? --Bth 08:42, 4 April 2006 (UTC)
FEASIBILIYY REPORT
"you have a fun fair in university. Youyou have to stall for anything prepare a feasibility report on it" help me before 10_4_2006
Please do your own homework.- Welcome to the Wikipedia Reference Desk. Your question appears to be a homework question. I apologize if this is a misinterpretation, but it is our aim here not to do people's homework for them, but to merely aid them in doing it themselves. Letting someone else do your homework does not help you learn nearly as much as doing it yourself. Please attempt to solve the problem or answer the question yourself first. If you need help with a specific part of your homework, feel free to tell us where you are stuck and ask for help. If you need help grasping the concept of a problem, by all means let us know. —Keenan Pepper 17:17, 3 April 2006 (UTC)
- Your question is also poorly written and impolite. Use proper English and say please, if you want our help. StuRat 18:24, 3 April 2006 (UTC)
- Probably not an English-speaker primarily, so some slack is granted. What's a "fun fair"? How about making your own wine and setting a vomitorium booth? It would be cheap to do , and very popular. GangofOne 23:19, 3 April 2006 (UTC)
- I'm pretty good at recognizing accents, even in writing. This person looks to be a native speaker to me, specifically a native speaker of British English. StuRat 07:44, 4 April 2006 (UTC)
- Yep, classic lack of grammatical articles. Superm401 - Talk 23:20, 4 April 2006 (UTC)
- THis follow up, Wikipedia:Reference_desk/Science#APOLOGY, says you're wrong, although probably correct about the type of English attempted to be spoken. GangofOne 22:03, 6 April 2006 (UTC)
- I'm not sure I believe it, though. Note that the apology is written in fairly good English. This makes me think they were just really sloppy on this post and didn't want to admit it, so made up that story about not speaking English well. StuRat 19:55, 8 April 2006 (UTC)
astronomy/cosmogeny
If the Cosmic Microwave Background Radiation is due to a single event in the history of the Universe, then why do astronomers continue to record it from every point in the sky? In other words, why has it not rushed by the Earth never to return? — Preceding unsigned comment added by Paul venter (talk • contribs)
- Perhaps not suprisingly, you can find your answer at Cosmic_microwave_background_radiation. Chapuisat 19:26, 3 April 2006 (UTC)
Afraid not - if anything, the author of that piece is also confused ....."The photons continued cooling until they reached their present 2.7 K temperature. Accordingly, the radiation from the sky we measure today comes from a spherical surface, called the surface of last scattering, from which the photons that decoupled from interaction with matter in the early universe, 13.7 billion years ago, are just now reaching observers on Earth." What an amazing coincidence! With 13.7 billion years to get here, the timing is such that they turn up just when we start looking, and even more amazingly are centred on Earth, since if Earth were not central to the "spherical surface" mentioned above, the radiation would not be isotropic. So nice try, but no cigar. User Paul venter 3 April 2006
- You're using a straw man argument. The article makes perfect sense, just not your misinterpretation of it. —Keenan Pepper 21:21, 3 April 2006 (UTC)
- Also, there is no such person as "the author of that piece". Wikipedia is collaboratively authored and edited. See Wikipedia:Introduction. —Keenan Pepper 21:23, 3 April 2006 (UTC)
If I misinterpret the article it is because it lacks logical clarity. On the other hand if you see sense in it, then please enlighten me in detail. As for whether the article has author or authors, it affects the credibility and logic by not a single iota. User:Paul venter 3 April 2006
- The universe is constantly expanding. Therefore, there are longer and longer paths for light from the big bang to take before reaching us. There is no need for an "amazing coincidence". —Keenan Pepper 00:05, 4 April 2006 (UTC)
If the 'spherical surface of last scattering' is expanding, the surface remains spherical and does not explain the isotropy or persistence of the CMBR --Paul venter 07:37, 4 April 2006 (UTC)
- The "surface of last scattering" is what happens when you look back in time to the early universe from some point inside the current universe. But from the point of view of the history of the universe, there was a particular point in time when the universe cooled down enough to become transparent (because the processes that absorbed and reemitted the photons all the time stopped). When we look back we see the light from the sphere formed by all the points that were at that stage at the right time for the photons they emitted to now be reaching us.
- But I rather suspect you're not interested in the real answer. --Bth 09:05, 4 April 2006 (UTC)
There are some difficulties here....firstly, the way I understand the theory is that it was a spherical surface and not a sphere which emitted the light. Secondly, was the emission a burst of light lasting only a very short time, a very long time or is it an ongoing process? If it were only for a short time, then the spherical shape of the emitting surface would mean that when the light does reach any point (except the geometric centre) within that sphere, its behaviour will certainly not be isotropic. And if it were a burst lasting only a short time, then consequently any observer within the sphere would only experience the light later on as a burst of radiation starting at one point in the sky and moving in the shape of a band to a point diametrically opposite - the complete cycle taking anything from seconds to billions of years, depending on where the observer is located inside the sphere.
What a strange thing to think that I am not interested in the real answer..... If you know the real answer, then do share it. --Paul venter 11:13, 4 April 2006 (UTC)
- My relpy was an attempt at explaining the real answer. But let's try another way. It is not really helpful to think of it as "a spherical surface emitting the light". The light is the light that was "emitted" when the universe became transparent -- that happened throughout the universe at the same time (in the appropriate coordinate system), about 300,000 years after the Big Bang.
- Now the important fact is that as we look out into the universe we are looking "back in time". This is not a special claim of the Big Bang theory, it's a consequence of the finite speed of light. Because it's about two and a half million light years away, we are seeing light from the nearest big galaxy, Andromeda as it was approximately 2.5 million years ago. It should be fairly obvious that there is a spherical shell of radius 2.5 million light years centred on us in which everything we see is at it was 2.5 million years ago, it's just that Andromeda's pretty much the only interesting thing in it. And further out you can have a shell of everything a billion years ago, further out still a shell of everything as it was ten billion years ago. When you get back to 13.4bn years ago, your shell contains the CMB photons because that's the time when the universe became transparent. Beyond that, you can't see because the universe wasn't transparent. That's why it's a spherical shell, it's just a consequence of the fact that we're looking back, the original emission was in all directions -- it's just that all the ones that didn't head off in the right direction for us to see them are out being part of the CMB as seen from elsewhere. The "last scattering" event (ie the universe becoming transparent) happened everywhere simultaneously, pretty much, because it was a consequence of the temperature of the universe, which was still very homogeneous at that point, dropping below the critical temperature needed for any atoms that formed to be instantly reionised -- after that the atoms that formed stuck around (until stars started forming and reionising everything). If you could follow the spot of the universe that we're in now backwards in time, you'd find that it too had been part of that process 13.4bn years ago. To a hypothetical observer 13.4bn light years away photons that were emitted then from our ___location now are just arriving as their CMB photons.
- Is that making any more sense?
- (Note that strictly the last scattering shell is not 13.4bn light years in radius as I've implied; when you factor in general relativity and the evolution of the universe it gets more complicated.) --Bth 12:00, 4 April 2006 (UTC)
OK..let's see whether I've got this right. About 13bn years ago (where does this figure come from?) there was a colossal expansion of a very large mass. The expansion was so rapid that after about 300,000 years the outermost edges of the expanding sphere had reached a radius of at least 13bn light-years, since 13bn years after the bang we are still receiving radiation from an event that took place at 300,000 years post big bang. This sphere of matter had at that time cooled sufficiently for internal scattering to end and to become transparent to radiation, resulting in a burst (short-lived?) of radiation which we now observe as the CMBR. This CMBR will have started arriving at Earth from 300,000 yrs post bang, continuously to the present moment, coming from spherical shells progressively further away. At some point in the future one presumes that the CMBR will cease fairly abruptly having come from the outermost shell of the big bang sphere at the moment of transparency - at which point also any radiation having come from outside the big bang sphere will become visible. I am still puzzled as to the mechanism which limits the distance to which we can observe - on the one hand we have the pre-transparency opaque barrier and on the other hand we have Hubble's Law driving matter to a speed faster than that of light. Please let me know whether I have at least the rudiments correct. --Paul venter 22:15, 4 April 2006 (UTC)
- In some sort of order:
- The 13bn years is derived from plugging the observational evidence into the theory. (Judging by some of your edits elsewhere on the 'pedia, you're unconvinced by the idea of a finite-age universe at all. I suggest you have a look at Olbers' paradox for a nice simple proof of that simply from the fact that the sky is dark at night.)
- According to the now standard version of the theory, the really rapid expansion was at the very earliest stage; see cosmic inflation.
- There wasn't an "expanding sphere" -- space itself was (and continues to this day) expanding. "Blowing up a balloon" analogies for the Big Ban only really work when you consider them from the point of view of observers embedded in the Flatland-like two dimensional surface of the balloon. The Big Bang was not in any way like a normal "explosion", it's an expansion of everything. (I think this may be the key misconception at play here?)
- No, the CMBR will not suddenly disappear in the future. We will see the earliest moments of parts of the universe currently inaccessible to us (the universe is bigger than the currently observable universe) -- every CMBR photon that arrives is from a region of the universe that until that moment was previously too far away to see. (But bear in mind that the universe was smaller at the CMB epoch.)
- The mechanism which limits the distance to which we can observe is the finite age of the universe. There's nothing to see "the other side" of the last scattering surface, everything earlier than that was opaque. An important but subtle distinction: no matter is being "driven to a speed faster than that of light", the universe itself is expanding with that matter embedded in it. (That expansion can be faster than c.)
- Any clearer for you? --Bth (not signed in) 5/4/06
A couple of points to note. Olbers' paradox : There could be any number of reasons for light from stars beyond a certain radius not being visible to us - big bang opacity and redshifted light being just two of them. By itself it certainly is not proof of a finite-age universe.
I carefully avoided use of the term 'explosion'
I also think the CMBR will never disappear, but for different reasons. However I'm confused - if the big bang bubble was of finite size at the moment of transparency, then surely at some time in the future, we will observe the CMBR from the last scattering surface. There could be no more CMBR from this particular big bang - or am I missing something?
"There's nothing to see "the other side" of the last scattering surface, everything earlier than that was opaque." I was under the impression that the opacity was a quality of the space inside the big bang bubble before transparency - did this opacity extend outside the bubble as well? Thank you for your patience --Paul venter 07:13, 6 April 2006 (UTC)
- Please explain what you mean by "Big Bang bubble". Even though you've avoided using the exact word, between that and your repeated references to "spheres" you sound an awful lot like you're falling victim to the "it's an explosion inside some pre-existing three-dimensional space" fallacy. --Bth 08:42, 6 April 2006 (UTC)
big bang bubble - My phrase, which perhaps I should have defined. Let me do so now. The bubble would include all matter resulting from the big bang/expansion. Radiation from the bubble would obviously define a much larger sphere. And you're quite right - I do think that the big bang was local and within a pre-existing infinite space in which no doubt countless other big bangs have taken place, are currently taking place, and will within the infinite future take place. Is there any good evidence to indicate that this is not the case? --Paul venter 11:56, 6 April 2006 (UTC)
Intermolecular Bonds
I can't figure out why, when I tear paper, the bonds holding the paper together on an intermolecular level break but when I put the two sheets next to one another and add pressure they don't form agian. It seems like a rather stupid question but I can't think of an explaination on a chemical (molecular) level. Thanks. -Haon 18:29, 3 April 2006 (UTC)
- Poor example as you aren't really breaking chemical bonds but physical bonds of interwoven fibers. You're just pulling the cellulose fibers apart. In order to get the paper to come back together you would have to reweave the Cellulose fibers back together. Chemically speaking, breaking bonds releases energy. Creating chemical bonds requires energy.
A good example of this is Sugar. Plants make sugar out of carbon dioxide and water using the Energy of absorbed light. (Photosynthesis) At same time all life (even plants) take the Sugar and use Oxygen to break it down into Carbon Dioxide and Water releasing the energy which was stored in it by photosynthesis. This process is called Cellular Respiration.--Tollwutig 18:39, 3 April 2006 (UTC)
- Chemically speaking, breaking bonds releases energy. Creating chemical bonds requires energy. This is wrong. If breaking bonds released energy, they would break spontaneously and molecules would not be stable.
- Plants use the energy they get from sunlight to break the strong bonds of H2O and CO2 and form sugars with weaker bonds. Animals break the weak bonds of the sugars and form the strong bonds of H2O and CO2 which releases energy.
- The stuff about interwoven fibers was the right answer. —Keenan Pepper 21:17, 3 April 2006 (UTC)
- Some chemical reactions are exothermic (releasing energy) and others are endothermic (using energy). Those reactions that release energy, like say the detonation of dynamite, are rather unstable, but still require specific conditions for the reaction to take place. Typically, this is some combination of heat and/or pressure. StuRat 07:37, 4 April 2006 (UTC)
- "when I tear paper, the bonds holding the paper together on an intermolecular level break but when I put the two sheets next to one another and add pressure they don't form agian". If you alligned the atoms EXACTLY the way they were, the bonds WOULD form again. The problem is , when you rip paper the ripped edge has about, oh, maybe about 10^22 bonds , give or take, that you have disturbed, and the atoms exposed are vibrating (at room temperature) and maybe combine with the air, and the fibers got jumbled and distorted, so when you put them together, they no longer match up. If you take the time to match up all 10^22 joints, then the joint will be seemless. Let us know when you're done. GangofOne 23:10, 3 April 2006 (UTC)
- Actually, this sort of thing can happen. It blew my mind when I first learned of cold welding. Chemical bonding, in addition to geometric considerations, is also a component of friction. As a poster above said, there is mechanical bonding involved in holding paper fibers together, but under the right conditions (particularly high-temperature polished surfaces in a vacuum) you can get all sorts of fun things to happen like sintering. —Ben FrantzDale 02:44, 6 April 2006 (UTC)
SARS relationship to Avian Flu, H5N1
I have spent considerable time studying the situation regarding the potential pandemic due to the currently circulating H5N1 A virus. SARS was also a virus, though of a different kind, and that pandemic was tightly contained. According to WHO about 8000 people fell ill with SARS and about 800 of them died. That is a miniscule set of numbers compared to even the most optomistic estimates of what might happen in the human population should H5N1 change to become easily transmitted among people. Why is there such a huge quantitative difference? How is it that we managed to survive SARS so well and seem to be so vulnerable to H5N1?
I have been to both the WHO and CDC sites as well as Wikipedia seeking some insights but I can find nothing. Everyone treats each illness quite independently of the other.
I'd appreciate any help you can bring to bear on this question. - unsigned
- H5N1 is pretty much a standard influenza virus and follows the same pattern as other. As for its ability to spread if it mutates to be contagious between humans, it'll spread like any other influenza. While I do not know the specific information on SARS pathogenicity, it is not as easily transmitted as influenza, which is only surpassed in contagiousness by the Common Cold. Influenza is contagious 12-18 hours before symptoms are ever apparent.(not sure about SARS). This means that someone who gets Influenza in Tokyo could get on a plane, spread the virus to all other passengers and arrive in L.A. with only a slight sniffle. In the meantime now you have several hundred people who are potentially infected, and not showing symptoms.
- As a side note the mortality rate of H5N1 is over exaggerated as the reports of 80% mortality are obscured by the fact that only the most severe cases have been reported. How often is H5N1 deadly in cases where the symptoms do not warranty treatment at a medical facility, and thus go unreported?--Tollwutig 19:44, 3 April 2006 (UTC)
- SARS has low inherent transmissibility. Flu has high inherent transmissibility. It's the difference between a fire on a dry grass plain and a fire on a wet grass plain. Extensive studies looking for mild missed H5N1 cases in Cambodia found NONE. Avian adapted H5N1 kills half the humans that get it, but has near zero human to human transmissibility. If and when a human adapted strain of H5N1 evolves, no one knows what its transmissibility nor what its mortality rates will be. We have no data to guess with because this strain is acting different (more deadly, more virulant, more transmissible) than all other known strains of flu - ever. The world's best experts say they are very scared and have stocked up months worth of food and water and medicine. Dr. David Nabarro, chief avian flu coordinator for the United Nations, describes himself as "quite scared"; says avian flu has too many unanswered questions; and if the disease starts spreading to humans, borders will close, airports will shut down, and travelers everywhere will be stranded. If the worst happens, the best way to survive is to lock your doors, stay inside,and have no contact with anyone outside your home for as long as your food and water last. In the 1918 pandemic some entire villeges were wiped out while some entire cities blocked all incoming traffic of any kind and had no deaths. WAS 4.250 21:11, 6 April 2006 (UTC)
Humming and Software
Does anyone know of any software where you hum/whistle/la/etc. into a microphone and it gives you an approximate pitch (or note)? Even better would be one where it measures the duration of the note as well and records it. The reason I ask is because I find it easy (as I am sure many other people do) to invent and hum a tune, but when it comes to playing it on an instrument or writing it down, I have no clue what to do (even though I can play music reasonably well). Alternatively, can anyone give me some pointers on how I would write a basic program that could do this? Any suggestions would be greatly appreciated. 80.229.152.246 20:27, 3 April 2006 (UTC)
- While I do not know of a specific program that does what you want in one complete package with a pretty pink bow on top, it isn't really complicated to record the microphone into a wav file and then convert the wav to midi. Once in midi, the notes will quanitized to specific pitches and durations. Also, there are many composition programs that allow you to view midi files as sheet music or rolling bar graphs so you can adjust it further. --Kainaw (talk) 22:01, 3 April 2006 (UTC)
- Used to be such a thing for sale. See also Vocoder, Fourier transform GangofOne 22:55, 3 April 2006 (UTC)
- "...and then convert the wav to midi." — That's equivalent to the original problem. —Keenan Pepper 23:52, 3 April 2006 (UTC)
- Apple's GarageBand (a part of Apple's $79 iLife suite) has an instrument tuner that shows what note is being played, and that includes through a plain ol' microphone. I had some fun humming "Do Re Mi" and seeing how close I was to actually humming the correct notes. Of course, GarageBand is Mac-only, so I doubt that'd help. :P —OneofThem(talk)(contribs) 00:28, 4 April 2006 (UTC)
- just record it regularly, and then match each note to a note on the keyboard or a guitar. the main problem is that youre probably not singing in tune, but tuned to some weird quarter note or half pitch to begin with. try playing a note on the guitar or keyboard, then matching that note, and then hum from there while recording it. then you can play it back and learn it. if you do this enough your ears will get real good at figuring out which note is which. or you could try what everyone else has suggested... if the point is to get good at playing at the instrument youre probably cheating yourself if you use a program to do the work for you modesty 01:56, 4 April 2006 (UTC)
- On a side note, a clean whistling sound is very similiar to a pure sine wave, which is really trivial to find a matching frequency with by using some mathematical tricks. I wonder if somone coded a program for this already, shouldn't be hard. (I did some nasty thing like this on mIRC, and while it did work, it didn't work all that nicely) ☢ Ҡi∊ff⌇↯ 06:06, 4 April 2006 (UTC)
- Software of the type the questioner is asking for must exist, because what he's describing is also the basic mode of operation of the Singstar games. --Bth 09:38, 4 April 2006 (UTC)
- Thanks everyone for your answers. The point was not to get good at playing the instrument but to see if a computer program has already been written. I'll probably have a go myself and put it on Sourceforge if it is any good. P.S. Thanks for the sine wave tip.
80.229.152.246 18:12, 4 April 2006 (UTC)
I was facing the exact same issue when I had to write a song for a project in college. I ended up using the Transcribe!, software, which is a very compact, but extremely easy to use program. You can hum the tune into your mic, which the program will record, and then show the waveform graph. You can then select sections (e.g. single notes that you hummed) within the graph, and the program shows you nice distribution graph of the pitches it detected in that section over a piano layout (see the screnshots section, and you'll understand). I then played the notes on my MIDI keyboard to determine which were the ones I intended to hum, and wrote the notes down. It's probably not the best program out there and isn't as robust as many others, but it was so simple to use, that I ended up sticking with it. Hope this helps. --Aramգուտանգ 05:49, 5 April 2006 (UTC)
Question about the VLA
In the article Very Large Array there is aline which reads:
- There are four commonly used configurations, designated A (the largest) through D (the tightest, when all the dishes are within 600 m of the center point).
What is this difference between these configurations, by which I mean what do they allow observers to see? are the images clearer in one configuration than another, or is this done simply to change perspective of an observed object?
- Briefly, wider array configurations give a narrower field of view and higher resolution. (This is one reason for the creation of the VLBA – the Very Long Baseline Array – which links a network of radio telescomes spanning 8,000 km). Moving the dishes closer together widens the field of view so that larger objects can be observed. Different configurations of the dishes represent different compromises between field of view, resolution, and apparent brightness of radio sources.
- Here's a schedule for the different configurations over the next few years. (The VLA is operated under each configuration for approximately 4 months at a time.) Finally, here's a technical publication detailing the resolution limits of the VLA in each configuration at a range of wavelengths. TenOfAllTrades(talk) 02:03, 4 April 2006 (UTC)
- Thanks. I apreciate it.
Chemical Reaction
I am making a battery out of a lemon for school. For the project, I am using a "juicy" lemon to create electricity. I am putting a strip of copper and a strip of zinc in the lemon so the zinc and copper don't touch. I want to know how the the juice from the lemon, copper, and zinc creates a chemical reaction to produce electricity. Please explain how the chemical reaction works and how it generates electricity, but please keep it relatively simple if it's possible (I'm only in 6th grade). Thanks! Anna
- Did you see the lemon battery article first? - Cybergoth 23:09, 3 April 2006 (UTC)
April 4
Neutrinos
It has come to my attention that we are under constant attack by neutrinos. I was shocked to learn that there has been no study of the health effects of these unwelcome particles. Has there been no attempt to build a neutrino shield? I believe it is a liberal conspiracy.
- Neutrinos are naturally produced and have been bombarding Earth since it was created (at least, that's what I'm assuming by reading the article on neutrinos). I seriously doubt that they're harmful, nor that there's a "liberal conspiracy" involved. (lol) —OneofThem(talk)(contribs) 00:40, 4 April 2006 (UTC)
A neutrino shield would have to be several million miles thick. With all that material, I'd rather build a dyson sphere. Night Gyr 01:01, 4 April 2006 (UTC)
- The neutrino article says you'd need something like a half light year of lead to make an impact on neutrino bombardment. Is this a serious question? If this is a conspiracy, daylight savings time is the government's way of stealing time from you. Isopropyl 01:13, 4 April 2006 (UTC)
If neutrinos are harmful to living things, you will never know. This is because it is impossible to have a control (case) to test the effects of not being bombarded with neutrinos. Ohanian 01:32, 4 April 2006 (UTC)
Given that all terrestial life has been under neutrino bombardment since since the Earth was created, removing those neutrino could theoretically be harmful. We know too little about them to say otherwise, and have no experimental or anecdotal evidence of whether life could even exist without their presence. Consider a somewhat extreme analogy - no-one knew much about oxygen prior to the 18th century - thankfully no-one decided to shield life from it. Or, to put it simply: it ain't broke - don't try to fix it. Grutness...wha? 01:49, 4 April 2006 (UTC)
- What I read was that the neutrino cross section of a human being per time is about 1 neutrino/70 years or so. When you actally interact with one, you die. How else can you explain this amazing coincedence? GangofOne 07:18, 4 April 2006 (UTC)
- Your ideas intrigue me, and I wish to subscribe to your newsletter. Tzarius 08:40, 4 April 2006 (UTC)
I would say they are both harmful and helpful. They are one of many factors which may cause genetic mutations. Most mutations have little effect, and at most kill the cell. However, some are harmful, such as causing cancer, and quite rarely they are actually helpful, if the mutation is in a reproductive cell and is beneficial. Thus, they may actually help to drive evolution. StuRat 07:24, 4 April 2006 (UTC)
- Neutrinos do not cause genetic mutations. --BluePlatypus 12:01, 4 April 2006 (UTC)
- While the vast majority pass right through the human body (and even the planet) without reacting, a rare few do cause a reaction. That is how we can detect them. If this reaction happens to occur by a strand of DNA, a mutation can occur. StuRat 20:00, 8 April 2006 (UTC)
Bots
I'd like to do some experimenting with internet bots (e.g. Wikipedia editing bot, Bluebot). What programming language does this require? Does anyone know good links for downloading a compiler or for a good tutorial? Thanks. -Snpoj 01:29, 4 April 2006 (UTC)
- AFAIK, many Wikipedia bots use Python. Different types of bots may be programmed using different languages. For example, I've programmed a responding IRC bot in Perl because of its efficiency in string handling. –Mysid 06:18, 4 April 2006 (UTC)
Has this already happened
- The folly of basing Scientific Research on unobservables events. Ernst Mach did not believe in the theory of the atom, saying that "atom" is just a word and nothing more.
- Mach went on. If you do believe in the atom, what would happen? Well physics will generate many many results. Physicists will construct models of the atom and then they will find out that these model do not work.
- So then physicists will replace the models with newer mathematical models because mathematical terms can be stretch to fit any data. And then physicists will end up saying that "because we can't observe it, we can't measure it. So the position might be this and the energy is probably that."
- Then the physicists will be driven to the theory that the energy comes and goes more or less at random. All sorts of trash will appear in their theory. There will be "elementary particles" with strange names and anti-matter which ought to be there but isn't. These "particles" would either behaving like a wave or discrete particles depending on the observable outcome. So the laws of physics will degenerate into mumbo jumbo.
My god! Imagine living in a world where this has already happened. What an utterly weird world it must be. Ohanian 01:40, 4 April 2006 (UTC)
- I don't know what your point is, but that quote is a fake. Melchoir 01:50, 4 April 2006 (UTC)
- Holy crap! They've figured out that we're making it all up! Run! -- An evil particle physicist 01:51, 4 April 2006 (UTC)
- Particle physics ain't simple and the mathematics correlates with experimentation. There's nothing wrong with revising "models" and making analogies to help us understand physical concepts on a microscopic level. imo, our inability to interpret obscure mathematics (the one "true", non-analogous model) is why quantum mechanics must appear to our mind as "mumbo jumbo". Trust the math even if we're destined not to fully comprehend it.
- As for the subject's question, do you mean stuff like Polywater and other forms of so-called Pathological science?
I believe the true test of any model, such as the model of the atom, is whether it can predict things which aren't already known. I believe the models of the atom have predicted most, but not all, atomic interactions. If we look at a simpler model, a globe is a model of the Earth. While not specifically designed to measure the distance from Bombay to London, it could be used for this purpose by laying a string on the globe between the two, then scaling up the string's length to account for the scale of the globe. However, in other respects, like the density, the globe may not be correct. Thus, it is a good, but not perfect, model. I think atomic theory falls into the same category. The earliest versions, with electrons in planar, circular orbits, is the least accurate, and the current, far more complex model with electrons inhabiting waveform probability functions, is the most accurate model. StuRat 07:15, 4 April 2006 (UTC)
- Read Feynman's books. – b_jonas 13:54, 4 April 2006 (UTC)
- And there is no such thing as a "perfect model" -- a model must, by definition, be something lesser than the ultimate truth. And for good reason, too! Not much one can do with a 1:1 map. --Fastfission 01:14, 5 April 2006 (UTC)
multi-language support website problem
Hai,
i am programmer in php . i am creating a website with multi-language support. i.e english,tamil,sinhalese support website. and my problem is how to show the site content in different languages.(because browser doesnot support the languages how to install fonts dynamically or how to use unicode support for my website). please any one provide a solution.waiting for your reply
Thanking you, sudhakar.
- Create your website in UTF-8 and use Content negotiation to select the language automatically. Installing fonts is not your problem, it is the problem of the website user. —Masatran 03:17, 4 April 2006 (UTC)
- I think he wants to make it his problem, so the user won't have to deal with it, but can still see the page correctly. - Taxman Talk 23:33, 4 April 2006 (UTC)
Does light have mass?
Does light have mass? I have only found conflicting or incomplete answers on the internet. Thanks
--Jared
- Photons (the particles that carry EM forces) have no mass, but can impart momentum -- see Compton scattering Raul654 03:46, 4 April 2006 (UTC)
- Nice explanation from the physics FAQ. EricR 04:59, 4 April 2006 (UTC)
Another planet?
If there were a planet similar to Earth in both size and solar distance, always orbiting on the opposite side of the sun, how would we be able to know it was there?
- Hmm... even if the Earth 2 were on an exactly opposite orbit from Earth at some point in time, perturbations from the other planets would affect the twins unequally, and that should eventually mess up the alignment enough to make Earth 2 directly visible from Earth. You could do a numerical simulation to figure out how long that would take; I'm not sure how to estimate it. Melchoir 04:37, 4 April 2006 (UTC)
- See Counter-Earth for more information. — Knowledge Seeker দ 04:48, 4 April 2006 (UTC)
- The orbit of earth around the sun is an ellipse. See Kepler's laws of planetary motion for why Earth 2 could never be always on the opposite side of the sun. EricR 04:56, 4 April 2006 (UTC)
- Then the other planet would have to be an ellipse. Without a symmetry-breaking influence (such as the other planets), there is nothing preventing another planet from occupying an exacly opposite orbit. Melchoir 05:26, 4 April 2006 (UTC)
- You're right of course. Looks like i also egagerated the eccentricity. EricR 05:50, 4 April 2006 (UTC)
- I think you were right to start with Eric, but I've posted my analysis as another question at the bottom of the page. DJ Clayworth 20:32, 6 April 2006 (UTC)
- Then the other planet would have to be an ellipse. Without a symmetry-breaking influence (such as the other planets), there is nothing preventing another planet from occupying an exacly opposite orbit. Melchoir 05:26, 4 April 2006 (UTC)
- My dad once theorized that there might be an identical Sun on the opposite side of the Milky Way with an identical Earth orbiting it that supports (and has) life on it, and that the only reason that neither Earth has detected the other is because we can't see through the center of the galaxy very well. :P —OneofThem(talk)(contribs) 17:29, 4 April 2006 (UTC)
- Recent work in viewing distant galaxies has used a gravitational magnifying glass sort of trick caused by the gravitational bend of clusters of nearer galaxies. Why wouldn't the clusters of stars in the center of the galaxy provide the same effect for seeing clearer images of the opposite side of the galaxy. But, to the point of this question, the opposite side of the Sun has been examined repeatedly by our satellites. I have no idea how many we've slung out into space, but many of them have seen around the Sun while looking at other planets, moons, asteroids, etc... --Kainaw (talk) 13:51, 5 April 2006 (UTC)
Tatto Help
Dear Readers, I'm in the middle of getting a tattoo but i cant find the formula for this saying. It goes,"Once you are Born, You begin to Die." Its not the actuall saying but thats what it means. There is a formula for this, the Theory starts with an "E". Please Help Thank You, Bare Skin
- Are you thinking of entropy? TenOfAllTrades(talk) 05:59, 4 April 2006 (UTC)
- And the best phrasing for that is Dylan's: "He not busy being born is busy dying." --jpgordon∇∆∇∆ 15:34, 5 April 2006 (UTC)
- Maybe you're thinking of Manlius? Once born we begin to die, the end depends on the beginning. Or any of the similar statements here: [4]. Personally, I vote for the entropy game rules: You can't win, you can't break even, you can not leave the game. Ande B 05:20, 6 April 2006 (UTC)
Cause of death
I am researching my family history and have a relative aged 19 months who died from " Tabes mesenterita" according to her detah certificat. Could anybody please advise what this is? Tired wikipedia amd medical networks but could only find that "tabes" means gegeneration - i think!
May thx
Andy
- A mailing list archive from 7 years ago contains a similar question. Maybe the words could have been Tabs Mesenterica, which means tuberculosis of the lymph glands inside the abdomen – a children's illness. (source) –Mysid 07:11, 4 April 2006 (UTC)
Your term is spelled correctly but is difficult to match to a specific modern diagnosis. Tabes is an old medical term that means wasting. It is a nonspecific term, and could have resulted from many different diseases. Mesenterica is the adjectival form of the word mesentery, which in modern medical usage refers to the tissue that connects the intestines to the rest of the abdominal cavity and contains lymph nodes and blood vessels. The interpretation might vary by the date and place of the death certificate: the term tabes was used more widely in French than English medical writing and survived in more contexts in the 20th century. In English, the term tabes disappeared from medical usage in the 20th century except as part of the term tabes dorsalis, which is a degeneration of spinal nerves caused by syphilis, not likely the cause of an infant's death.
I also suspect mesenteric may have also been used before the late 19th century in a wider sense to mean "intestinal" but I am not certain of this.
If the death certificate was in English and before the late 19th century, the diagnosis was probably not based on an autopsy or diagnostic tests, and so represents a description of the disease process. Describing wasting as a cause of an infant's death mainly implies that the cause of death was not physical trauma, acute infection or illness, or sudden cessation of breathing but a more prolonged process in which failure to thrive was the chief manifestation. If I am correct that a practicing physician might use the term mesenteric more broadly to imply "involving the intestines or abdomen", then it suggests that diarrhea or abdominal distention were the most prominent signs of the illness. There are many causes of failure to thrive with gastrointestinal manifestations that could have led to death before the 20th century: cystic fibrosis, or chronic infection such as tuberculosis. The other type of abdominal disease that could have caused a wasting death would have been an obstruction of the stomach or intestines (e.g., pyloric stenosis, duodenal atresia). I do not know whether tubercular mesenteric adenitis could cause enough enlargement to be palpable in the abdomen and identifiable by a doctor as a cause of death without an autopsy. Can you give us some more context (date and ___location of death)? alteripse 11:30, 4 April 2006 (UTC)
How to change the magnetic strength of the magnet bar ?
I have one magnet bar and one ion bar , one man talk me that he can make the magnetic field of this magnet,it shall be stronger or weeker by placing one ion bar with the adjustable thickness . Do you aggree this?
Location of the first observed point : Z, Location of the magnet bar : M, Location of the ion bar : I, Location of the 2nd observed point : Y
Z-------------MI-------------Y
Case (1): thickness of the ion bar is 5mm; Case (2):thickness of the ion bar is 1mm
In the case (1), we use one ion bar which is applied to the magnet bar with the thickness of about 5mm . In the case (2), we use one ion bar which is applied to the magnet bar with the thickness of about 1mm .
At the point of Z, (in the both cases) the magnetic field is the same strength.
And at the point Y in the case (1), by causing of the reluctance effect , and the thickness of the ion bar is thicker , the magnetic field shall be weeker than the point Y of the case (2) . A man talk me that he can make the magnetic field of this magnet,it shall be stronger or weeker by placing one ion bar with the adjustable thickness . I.e. that he want to talk at the point of Z: At Z in the case (1), the field is smaller than Z in the case (2). Is it right? Wiki
- Your diagram doesn't seem to display for me, because it's on your computer. You need to upload it to Wikipedia so we can see it. Try using the "Upload file" link on the left to do this.
- Changing the material and material quantity can have an effect. Some materials, like iron, conduct magnetic fields better than others, like air. Resistance to a magnetic field is called reluctance. StuRat 08:43, 4 April 2006 (UTC)
Kids, if you find an ion bar on the street, do not touch it!!! They can be very reactive, and are used to propel starships. --Zeizmic 15:18, 4 April 2006 (UTC)
- Is that kinda like an oxygen bar? --jpgordon∇∆∇∆ 15:33, 5 April 2006 (UTC)
Using the same disk space for swap space and pagefile on a dual boot computer
My situation is as follows. I have a dual boot computer with Windows XP and Ubuntu 5.10. I have told Windows to put its pagefile in a dedicated partition located at the beginning of the hard drive (I have just one). My question is: can I tell Linux to use that pagefile as a swap file in an effective way? Just telling it the standard way (swapon etc.) does not work well because apparently it tries to mount the swap space before that partition, and so it cannot see it. When it mounts that partition later, it does not know that it has to swapon that file again. So the result is no mounted swap space. I was also told (Google groups) that I could format that partition to a swap partition every time Linux starts and format it back to FAT32 every times it shuts down (and re-create the swap file), but I do not know how to do this. Can anyone give me advice, please? Any suggestion about using the same physical space for swap/virtual memory is very welcome. Cthulhu.mythos 10:16, 4 April 2006 (UTC)
- It's possible, but it's not easy to do.
- You can use the same file in both linux and windows as a swap file, but the problem is that both linux and windows require that the file is prepared in a special way before it can be used as a swap file (this is in contrary to BSD, which I think doesn't require this). For linux, this is easy to do, because you can use the mkswap utility every bootup before you turn the swap on. For windows, it's more difficult, because there's no simple way this preparation can be done. I've read about this problem a few years ago, and it said that a kludge that works is to save the first few blocks of the file after windows have prepared it, and resore that every time linux is shut down (I've never tried this myself). However, that was ages ago, for an older version of windows, and at the time when hard disk capacity was more expensive. These days, it's probably not a problem to allocate separate swap space for each OS you install. (Still, if you insist, I wouldn't recommend making a FAT partition every time linux shuts down, I'd rather use a swap file instead of a partition.)
- Yeah, I've found the document talking about this: Linux Swap Space Mini-HOWTO. – b_jonas 13:36, 4 April 2006 (UTC)
- Thanks. It does semm quite difficult, actually. But maybe I will try to do it for the sake of it. Cthulhu.mythos 12:17, 5 April 2006 (UTC)
- If you want to do it for the geek/hobbey value, knock yourself out, but otherwise, I'd say it's not worth it. hard drive space is cheap. For great justice. 00:01, 6 April 2006 (UTC)
- Thanks. It does semm quite difficult, actually. But maybe I will try to do it for the sake of it. Cthulhu.mythos 12:17, 5 April 2006 (UTC)
- One more note. Do not set a too large swap space, as that wastes the main memory. Twice the size of the memory is enough. – b_jonas 19:55, 7 April 2006 (UTC)
Heliocentric
The word Heliocentric is taken from astronomy (sun centered model. What would be the term in social meanings - when a system is centered around a person?
- A particular person, or people in general? "Anthropocentric" for the latter, not too sure for the former, it would probably depend on what makes that person so special that they have a system built around them. You might get more useful replies over at the Language refdesk, to be honest. --Bth 10:56, 4 April 2006 (UTC)
Thanks :-)
Mental illness: Medicine
I want detailed reading that would throw light on what factors could show that a person did or did not have a mental illness in the past, if there is no evidence of it in the present
Please reply, My email is (address removed to prevent e-mail spam)
THANKS!!!
- It's difficult enough if you are a mental health professional with access to the patient. Any speculation like this, while possibly fun, is simply speculation. For great justice. 23:59, 5 April 2006 (UTC)
- You need to do a search for "forensic psychiatry." To get decent texts, you should try a college library, preferably one with an affiliated medical school. Public libraries are often able to do inter-library loans for works kept in nearly any library imaginable, including foreign libraries. Ande B 05:28, 6 April 2006 (UTC)
Old names for illnesses
I was looking at the vital statistics in an old almanac a few months ago and discovered a list of the number of people who died from different diseases and ailments - among which were "Cats in the belly" and "Planet". I've hunted both online and offline and cannot find any clue as to what Planet might be, though I found some mention of cats in the belly related to problems with childbirth. Can anyone throw any light on what these ailments might be? Grutness...wha? 13:51, 4 April 2006 (UTC)
- I can help with the second one - "planet" listed as a cause of death was saying that the death of the person was caused by a planet being in the wrong place, and causing so much misfortune that the person simply keeled over. Astrology taken to an extreme, if you will. Looking at it from a modern perspective, it was an explanation given by doctors for deaths which didn't have an obvious cause, at least not to the medicine of their time. Possible 'real' causes might have included things like strokes, heart failure and other sudden-death conditions which give little warning. — QuantumEleven | (talk) 17:11, 4 April 2006 (UTC)
an interesting question...
hey guys......can someone explain me why some types of substances are insoluble(in pure water) but soluble in acid or in base?? just like zinc, calcium carbonate,zinc oxide.
- It is because the substance is insoluble in water, but reacts with acid or base to create a soluble product. For example, calcium carbonate (which is insoluble) reacts with hydrochloric acid to form calcium chloride, which is soluble: CaCO3(s) + 2HCl(aq) → CaCl2(aq) + CO2(g) + H2O(l) -- AJR | Talk 16:50, 4 April 2006 (UTC)
- Can you do my homework for me too, AJR? —This unsigned comment was added by 12.41.204.3 (talk • contribs) 19:47, 4 April 2006 UTC.
John MacAdam
John MacAdam invented the hardtop roads, but I would like to know when and how. Your page on John MacAdams is small and says nothing (besides the tiny nibble I added) about hardtop roads.
someone anser me...plzzzzzzzzz
- Did you check the related article on macadam? — Lomn Talk 15:34, 4 April 2006 (UTC)
Research Goya theory?
I am trying to find information on a theory proposed several years ago by persons unknown ( I can't remember a name.) to the best of my knowledge he was located somewhere in England and as best as I can remember the title of the theory was THE GOYA THEORY. The rudiments of which were that a natural balance exists in nature to wit: that every element attempts to attain a state of equilibrium so that for example hot and cold will gravitate toward a medium temperature.That is simplistic I realize but the best example I could come up with on short notice.
- Any and all help appreciated. Yours truly,Jim Pfaff
- See Gaia hypothesis. Frencheigh 15:41, 4 April 2006 (UTC)
Thanks much,Jim
Dogs Watching Television
My grandmother used to have a West Highland White Terrier that was able to notice other animals on the television and respond with growls and barks etc. But my attempts to get our Alsation-Collie cross to notice other animals on the television have all failed. He just wont look at the TV. Why wont my dog watch the tele? --Username132 (talk) 15:20, 4 April 2006 (UTC)
- Dogs mental capacity differs from animal to animal. Same with other animals. I used to have a dog that did not like the mirror I had leaned up against the wall. She would go clear up over the bed to avoid walking next to it. When I blocked the bed route, she went past it at a trot with her head down and would not look at it.
- Right, one of the dogs is smarter than the other one. You work out which is which. --Trovatore 21:35, 4 April 2006 (UTC)
The family used to have a cat that would look behind the mirrror to try to find that other cat that looked like her. We used to have a creepy cat statue with eyes that seemed to follow you, the housecat would raise his hackles the first time he saw that. When you say the dog won't look at the TV, do you mean the dog actively avoids the set, or just shows no interest? I suggest running a tape of a barkign dog on TV, and see what that does.
- I can think of two reasons why a dog wouldn't see a TV image as the real thing. One is that they may have a different persistence of vision than humans. That is, they may see the TV image as a series of still images, not as motion, as we do. The other is that dogs rely less on vision, and more on other senses, particularly smell, than humans. So, if the TV doesn't smell like another animal, they don't believe it. With humans "seeing is believing", whereas, with dogs, "smelling is believing". StuRat 02:22, 5 April 2006 (UTC)
- I've grown up around dogs my entire life, and I've always been curious at their reaction to the television. Eventually I learned that animals simply have a greatly different perception of the world from humans. We, for example, live in a world of symbols: we have an intuitive understanding of symbolic representation, such as letters for words and words for actions and things. This symbolic understanding extends to 2-dimensional pictures as 3-dimensional objects: while we take for granted that the illuminated flashing box is showing us representations of real objects (like animals), it is unlikely that most dogs can make that logical leap (they don't drool at dog food commercials, for example). It is far more likely that the terrier was responing to the sounds of the televised animals, and did what dogs do: he barked back. – ClockworkSoul 03:34, 5 April 2006 (UTC)
- You could perform a small test on your dog. Find a copy of the album Animals by Pink Floyd. There's a track on it called, simply, "Dogs". In the background it has sound effects of dogs barking. Over the years I've had a few dogs and some of them reacted to the barking while the rest don't acknowledge it at all. This would at least give you an idea as to whether it's the television he's avoiding or if he's just not interested. Dismas|(talk) 10:01, 5 April 2006 (UTC)
- Here's the status in our household: Stella, a big fluff of a chow/German shepherd/Aussie mix, watches stuff on TV. The most fun was a few years ago when a squirrel ran out onto the field at Pac Bell Park during a Giants game; Stella started acting exactly as she does when she spots a squirrel in the great outdoors. However, she utterly ignored it when we replayed it for her on the Tivo. Mr. Slick, a great big lummox of a boycat who has always lived indoors, is fascinated especially when we put on videos of birds and critters, and even when the TV is off or on the news, will sometimes go and try to find the birdies behind the TV. (We had to stop leaving the bird video on because we worried he would scratch through the screen of the LCD TV.) The other two cats, however, spent a fair amount of their youth as outside cats, and are not in the least bit impressed or even interested in the TV birds. So, yeah, it varies dramatically from critter to critter. --jpgordon∇∆∇∆ 15:29, 5 April 2006 (UTC)
Pyrite and Sulphur
Please can you tell me what type of rock (sedimentary rock, igneous rock or metamorphic rock) sulphur and pyrite are? Computerjoe's talk 19:20, 4 April 2006 (UTC)
- Actually, they are both considered minerals, not rocks. --Ed (Edgar181) 19:28, 4 April 2006 (UTC)
- Very well, but would it still be possible to class them under one of the above three? Computerjoe's talk 20:18, 4 April 2006 (UTC)
- I don't think so, because rocks and minerals really have distinct definitions. Minerals have a homogeneous composition and rocks are defined as aggregates of different minerals. A mineral might be a component of different rocks that fall into each of the three classes. --Ed (Edgar181) 20:40, 4 April 2006 (UTC)
- Thank you Ed! :D Computerjoe's talk 21:16, 4 April 2006 (UTC)
- I don't think so, because rocks and minerals really have distinct definitions. Minerals have a homogeneous composition and rocks are defined as aggregates of different minerals. A mineral might be a component of different rocks that fall into each of the three classes. --Ed (Edgar181) 20:40, 4 April 2006 (UTC)
- Very well, but would it still be possible to class them under one of the above three? Computerjoe's talk 20:18, 4 April 2006 (UTC)
weather
what device points the way the wind is blowing —The preceding unsigned comment was added by 24.182.128.238 (talk • contribs) 19:43, 4 April 2006 (UTC)
- Perhaps a weather vane? Isopropyl 19:48, 4 April 2006 (UTC)
You don't need a weatherman for this. Just keep a clean nose, be careful of the plainclothes. --Trovatore 19:49, 4 April 2006 (UTC)
- Any way the wind blows, doesn't really matter to me. Isopropyl 23:24, 4 April 2006 (UTC)
Politicians use straw polls to determine which way the wind is blowing, which is occasionally affected when one of the gasbags releases more hot air than usual. StuRat 08:56, 5 April 2006 (UTC)
What's the deal with Firefox freezing on Macs?
In my office I use a mac, and I find that Firefox often freezes if it encounters something it doesn't know how to handle. For instance, if I were to try to go to text twist, a page with, I think, shockwave, Firefox will freeze completely and I have to force-quit out of it. This happens on maybe 20% of pages with odd media formats within them, so at least once a day. I'm using a brand new iMac with a pentium chip, barely used, and the latest version of Firefox. The exact same thing happens on the two-year-old iMac in the office, so I don't think it's just my computer.
When Firefox in Windows reaches something it can't handle, it tells me so or just refuses to load that page. Here on the Mac I have to force-quit, losing all my tabs and anything I've been working on in Firefox. How can I get it to be a bit more graceful in dealing with unexpected formats? — Asbestos | Talk (RFC) 20:03, 4 April 2006 (UTC)
- Actually, I suffer quite a bit with Windows. If you get a chance, use talkback. This enables developers to search BugZilla much quicker. Also, you could search BugZilla. Computerjoe's talk 20:17, 4 April 2006 (UTC)
- Are you using the latest versions of OS X and of Firefox? It is rock solid on my machine. Why are you using Firefox? Is there some specific function you need, or might Camano or Safari meet your needs? For great justice. 23:52, 5 April 2006 (UTC)
- Ahh, but it's Java, not Shockwave, which is probably the reason why you're freezing. In general, the Java VM likes to freeze things. Although, last time I used OSX, browsing with Safari (I think a month or two ago), and used Java, it was fine. Maybe check your Firefox plugins and check that Java is going OK? -- Daverocks (talk) 10:25, 6 April 2006 (UTC)
Recharging Alkaline Batteries
Are alkaline batteries rechargeable? This website claims that they are. I remember seeing expensive batteries chargers a few years ago that wre supposed to be able to recharge ordinary batteries. --Username132 (talk) 20:04, 4 April 2006 (UTC)
- The website and experiments seem pretty well thought out. I don't see any reason to doubt him. Obviously the manufacturers would warn you against this, both to cover themselves against you over-charging and getting acid on yourself, and because they'd be losing out on the sale of a battery. — Asbestos | Talk (RFC) 20:22, 4 April 2006 (UTC)
- I've got an alkaline recharger. It's great when it works, but when it doesn't, the batteries leak inside the charger or, worse, in use. The problem is the utter randomness of the failure mode. Sometimes a battery lasts for dozens of charges, but the next battery of the same type goes splat on the first charge. It's not too bad for powering cheap devices like torches/flashlights, if you don't mind having to clean them out occasionally. I've also tried "rechargeable" alkalines. They barf less frequently, but the highly caustic stuff that comes out burns your fingers, and the slight extra reliability is not worth the risk and the higher cost. Now I use NiMHs in any device that costs more than the batteries, and they never fail. --Heron 20:28, 4 April 2006 (UTC)
Make database backup using phpMyAdmin
How do I make a database backup using phpMyAdmin for a mySQL database. I need something I can save on to a CD. Thanks Gerard Foley 21:32, 4 April 2006 (UTC).
- The phpMyAdmin documentation (either distributed or online) is probably a better reference, but you're basically looking to export the relevant database(s) to files (compression is unlikely to matter if you're saving them to CD), making sure to export both structure and data. There may also be some form of "export all" function, but if so, I am not aware of it. — Lomn Talk 22:23, 4 April 2006 (UTC)
- I found an export button, but I can't find where the file gets saved. Gerard Foley 23:27, 4 April 2006 (UTC)
Doug Hall: What did he invent
Besides brainstorming processes and other business practices, what's this American Inventor judge's claim to fame? The average American house is supposed to have 18 of his inventions. Yet does this guy publish a list anywhere?
These are the only two relevant links I can find...
http://www.fansofrealitytv.com/forums/showthread.php?s=82a4ef00100cece6411be2fed9b8d48a&t=52829&page=2 http://www.eurekaranch.com/experience/
He's cited in two patent applications, through a "Personal Engineering" article, though not involved with them.[5] He's invented Eveready Lead Free Battery and Crystal Pepsi, but there's no other web references to him, it seems.
So... is he for real? -- Zanimum 21:41, 4 April 2006 (UTC)
- A bit more information "Doug Hall began his inventing career at age 12, inventing and selling a line of magic and juggling kits. After earning a chemical engineering degree from the University of Maine, he joined Procter & Gamble, where he rose to the rank of Master Marketing Inventor -- inventing and shipping a record nine innovations in 12 months."[6]. That's about all the information you're going to get because:
- "3. What are the 18 products or services in the average American home?
- Sorry we can’t tell you. Our contracts with clients require us to remain silent even after the products are introduced.
- The Eureka! Ranch business model is based on “contract inventing.” We are an invention think tank. We are paid a fee for our inventing as opposed to a royalty. We do our work under a “work for hire” agreement. This means that we are not named on patents and have no claim of ownership.
- The basis for the claim of 18 products and services. In truth we have invented or helped reinvent many more than 18 – 18 is the average in each home. And that’s less than half of our work as the majority of our invention consulting work is for industrial and international companies.
- The claim of 18 is based on a nationally representative survey conducted in 1996. The true number today is much higher. When you realize that we work for such clients as Procter & Gamble, Johnson & Johnson, Frito-Lay, Pepsi, American Express, Bank of America, Kraft, Ford, etc., it’s easy to understand how the numbers get so large – so quickly.
- Invention Licensing: In addition, I’ve personally negotiated licensing agreements on behalf of clients with the National Football League, Major League Baseball, Parker Brothers, Henson Associates, Garfield & Friends and Random House." [7]. --Fuhghettaboutit 22:37, 4 April 2006 (UTC)
April 5
Canon Pixma MP780 troubleshooting.
I have a Canon Pixma MP780. It is an all-in-one printer (copies, scans, faxes, does photos, and prints). It is powered via a USB cable. Out of the blue, it has ceased to power on. The black (3e I believe) cartridge is full, but the cyan, magenta, yellow cartridges, and the other black cartridge is empty, although I don't think that has anything to do with the situation... What could be the cause? What can I do to solve this problem? Javguerre 02:10, 5 April 2006 (UTC)
- Its likely not your ink, I don't want to sound like I'm stating the obvious but check your power cables. If you have a multimeter try checking to see if voltage comes out of the power supply. Let me know if those help, I can look up some more things to try if necessary :) -- Tawker 07:34, 5 April 2006 (UTC)
Try a different USB cable, and try it in a different USB port, or, if possible, on a different computer to elimate failure of your cable or computers usb ports. For great justice. 23:57, 5 April 2006 (UTC)
Dogs
Why do dogs run? Thanks. The pizzaman 19:03, 5 April 2006 (UTC)
- To get to the other side. --Optichan 20:54, 5 April 2006 (UTC)
- Faster. ☢ Ҡi∊ff⌇↯ 01:34, 6 April 2006 (UTC)
- Because they can. User:Zoe|(talk) 23:47, 5 April 2006 (UTC)
- Because they are predators. Before they became lapdogs, they hunted in packs, and had to chase down prey in order to eat. Also, they had to run away from predators. It makes some sense that they are driven to run, even though they may not 'need' to anymore, it's such a part of their biology. For great justice. 23:49, 5 April 2006 (UTC)
- No such thing as a dumb question? This is asking like why dogs can walk. --
Mac Davis] ⌇☢ ญƛ. 07:16, 6 April 2006 (UTC)
Multithreading in Fedora Core 4
I've successfully installed the second processor in my Proliant 3000, but things don't seem to be any faster than usual. Is there something I need to install or trigger to activate multithreading in Fedora Core 4? If a program wasn't designed for multithreading, can an OS split its requests up across two threads for faster processing? Is there a more suitable distribution to take advantage of the two processors (FC4 takes nearly 10 minutes to load). --Username132 (talk) 03:26, 5 April 2006 (UTC)
- Is this an existing install of Fedora or a new one? -- Tawker 07:32, 5 April 2006 (UTC)
- To take advantage of multiple processors, you need an SMP kernel. I believe that this is included in a Fedora install if the installer detects multiple processors; otherwise you need to install it yourself - Fedora RPMs definitely exist, and shouldn't be too hard to find (it's called kernel-smp or linux-kernel-smp or something like that). Once you've installed the RPM, you need to restart your computer.
- As for the advantages, the only performance increase with most applications will be due to one processor handling the OS overhead while your application gets the other all to itself. Some programs (mostly scientific simulation software) can be recompiled to take advantage of double processors, but most desktop software can't. 61.48.162.166 11:26, 5 April 2006 (UTC)
- When you say "things don't seem to be any faster" can you be specific about what you are measuring? It will be rare (though not unknown) for any *single* program to give greater throughput on multiple processors. Multiple processors benefit multiple programs. If a program wasn't designed for multi-threading, there is no magic available to make it multi-thread. Notinasnaid 11:37, 5 April 2006 (UTC)
- What I meant was that it still takes about 10 minutes to load the operating system. --Username132 (talk) 19:03, 5 April 2006 (UTC)
- Most Unix systems I've seen first run in the Kernel, single threaded. They spend a lot of time checking devices, which is not going to be related to the number or speed of CPUs. Then they start all the daemon processes. There is potential here to use dual CPUs, but the systems I have seen do not; they start them one after another, often with series of built in delays. So boot time isn't very much dependent on the kind of computer. What will improve it is removing unnecessary startup. A bold move would be to identify startup scripts which are independent of each other, and write a framework to multiprocess them. Maybe some Linux distributions have already done this. Mac OS X has done this. Notinasnaid 20:05, 5 April 2006 (UTC)
Nitroglycerin
I will take this time to ask a foolish question, could Nitroglycerin be used in propelling a craft pecifically a spaceship?
- Not a spaceship: the chemical formula for nitroglycerin is C3H5(ONO2)3. When exploded, it combines with oxygen to form the stable carbon dioxide, water and nitrogen molecules. The vaccuum of space, having very little oxygen with which to react, can't support the reaction. Even in within the atmosphere, however, propulsion with something as terribly unstable as nitroglycerin is a very bad idea: pure nitroglycerin is so reactive that it has been known to explode after receiving even the tiniest of jolts, or even by changing temperature by as little as 1 degree too quickly. Nasty stuff. – ClockworkSoul 03:49, 5 April 2006 (UTC)
- To explode nitroglycerin does not requires oxygen (or anything else). Pure nitroglycerin is too unstable to be used as rocket fuel. -Yyy 06:12, 5 April 2006 (UTC)
- I can't see any reason to think it would be a particularly good fuel even if stability weren't a problem. High explosives don't have particularly high energy density; they just release it very very fast. --Trovatore 06:25, 5 April 2006 (UTC)
- Just for the record, fuel+oxygen reactions are used in rockets, commonly in fact. See liquid oxygen. --Bth 12:44, 5 April 2006 (UTC)
- That's true, but rockets bring the oxygen with them. – ClockworkSoul 13:56, 5 April 2006 (UTC)
- Solid rocket fuel contains all the necessary oxygen within itself and does not rely on additional atmospheric oxygen. It is a relatively simple recipe. You may want to check out some of the amateur rocket sites if you are curious about the properties, stability, ranging, and targetting of such devices. Ande B 22:23, 5 April 2006 (UTC)
- Unless you're using a Hybrid rocket. Solid fuel+gaseous/liquid oxidizer. Nitroglycerin is a liquid anyway. Night Gyr 17:39, 7 April 2006 (UTC)
- Hybrid, now that's cool! I always found it ironic (as have many others) that nitroglycerine, combined with a few binders to make a nice little pill, could keep the heart from exploding. Ande B 01:53, 8 April 2006 (UTC)
- Unless you're using a Hybrid rocket. Solid fuel+gaseous/liquid oxidizer. Nitroglycerin is a liquid anyway. Night Gyr 17:39, 7 April 2006 (UTC)
- Solid rocket fuel contains all the necessary oxygen within itself and does not rely on additional atmospheric oxygen. It is a relatively simple recipe. You may want to check out some of the amateur rocket sites if you are curious about the properties, stability, ranging, and targetting of such devices. Ande B 22:23, 5 April 2006 (UTC)
- That's true, but rockets bring the oxygen with them. – ClockworkSoul 13:56, 5 April 2006 (UTC)
- Nitro would be unsuitable as a rocket fuel mainly due to its instability. The instant you lit off the engine, the shock would set off a sympathetic detonation in the rest of the supply. Also, explosions are less efficient than a steady burn due to the danger of damaging the ship and corresponding need for stronger (i.e. heavier) engines and nozzles. Night Gyr 17:39, 7 April 2006 (UTC)
How is modulation diffrent from multiplexing?
this is regarding networks communication,i am always getting convuse between these words,can u plz make it clear, it would be so great and thankfulll to u .thanks a lot --- viv
- If I'm reading correctly the main difference is modulation uses one channel whereas multiplexing uses multiple channels.
In telecommunications, multiplexing (also MUXing) is the combination of two or more higher level channels into a single lower level channel such that a reverse process, known as inverse multiplexing, demultiplexing, or demuxing, can extract the original channels. The individual channels are identifiable by a predetermined coding scheme.
vs
Modulation is the process of varying a carrier signal in order to use that signal to convey information. The three key parameters of a sinusoid are its amplitude, its phase and its frequency, all of which can be modified in accordance with an information signal to obtain the modulated signal. There are several reasons to modulate a signal before transmission in a medium. These include the ability of different users sharing a medium (multiple access), and making the signal properties physically compatible with the propagation medium. A device that performs modulation is known as a modulator and a device that performs the inverse operation of demodulation is known as a demodulator. A device that can do both operations is a modem (a contraction of the two terms).
Cheers -- Tawker 07:31, 5 April 2006 (UTC)
Thin
If you thickened something with starch, is there anything easily available to thin it a bit? 57.66.51.165 10:18, 5 April 2006 (UTC)
- Did you try water?--Adam
(talk) 16:20, 5 April 2006 (UTC)
According to some places, that makes it thicker owing to the grains swelling. Plus, I kind of need it concentrated. 57.66.51.165 16:23, 5 April 2006 (UTC)
- It's possible that if the mixture is so thick that the starch is not fully disolved, that might be true, but then you would have a really thick paste, almost a solid. Water is the way to go I'm afraid. For great justice. 23:47, 5 April 2006 (UTC)
Small switching PSUs 400 VAC -> 24 VDC
Hi, I'm trying to find someone selling small switching PSUs (for mounting in an enclosure). Wanted voltages: 400 VAC->24 VDC. I haven't found anything with a lower power rating than approximately 100 W, and most of them are quite bulky (the smallest side can't be bigger than 65 mm or they won't fit). There are loads of alternatives for 230 VDC voltage though. Does anyone know of a suitable inexpensive alternative, available in northern Europe/Scandinavia? 62.119.184.141 12:20, 5 April 2006 (UTC)
- If I were trying to get hold of a not-so-common component like that, I would try RS[8] or Farnell[9] (both links are to their lists of national sites) both of whom generally have a good range. Or if you have a regular supplier who doesn't list what you're looking for, have you tried asking them if they can order something for you specially? -- AJR | Talk 19:16, 5 April 2006 (UTC)
- I had already tried Farnell, didn't find any. I tried RSComponent as well - my search for "PSU 400VAC 24VDC" didn't get any answers (except partial matches - there are lot of 24VDC PSUs). And a custom-made solution isn't really in the question I think - the number of units needed is pretty small. 62.119.184.141 09:51, 7 April 2006 (UTC)
dear sir/madam, I would like to know, what makes the best lubricant to smear on my penis. i have tried sunflower oil, but my girlfriend says that it burns too much. This may sound juvenile, but I really have a problem. Thank you very much for your time,
--86.16.167.4 15:09, 5 April 2006 (UTC)
- There are many products specifically designed for that. You might want to look at personal lubricant. --Ed (Edgar181) 15:14, 5 April 2006 (UTC)
- Assuming you are a young couple, my first impression is you are not taking your time with her enough. If you have plenty of foreplay you should not need a lubricant, as her sexual arousal will be enough to provide that.
- You may be right but many young women actually need the assistance of a lubricant and should not feel that they are somehow "inadequate" because of that. There are plenty of good water based or silicon based alternatives to oil so that the couple can experiment with a number of them to get the right one for their life styles. Ande B 22:32, 5 April 2006 (UTC)
- Right. Maybe he's talking about anal sex?... —Keenan Pepper 17:25, 5 April 2006 (UTC)
- Then he should say so, there are different considerations for such activity. He may want to check out the alt.sex.faq that was developed quite some time ago but is still fairly comprehensive. Ande B 22:32, 5 April 2006 (UTC)
- "alt.sex.fag"?
- grin. No q not g. - Mgm|(talk) 12:34, 6 April 2006 (UTC)
- "alt.sex.fag"?
- Then he should say so, there are different considerations for such activity. He may want to check out the alt.sex.faq that was developed quite some time ago but is still fairly comprehensive. Ande B 22:32, 5 April 2006 (UTC)
- Right. Maybe he's talking about anal sex?... —Keenan Pepper 17:25, 5 April 2006 (UTC)
Cockpit Automation Philosophy
Sir or Madam, I am currently writing a graduate-level paper on the differences between the cockpit automation philosophies used by Boeing and Airbus and am attempting to locate greater factual and/or 'learned opinion', vice the readily-available lay-opinion comparing the two. Any assistance would be greatly appriciated; thank you in advance.
- All I can offer is one of those readily available lay-opinions: There is concern that a high level of automation will lead the pilot and copilot to pay less attention, thus causing more accidents. However, this is really just a specific example of one of the problems inherent in human interaction with fault tolerant design (where the "faults" are caused by inattentive humans). StuRat 17:43, 5 April 2006 (UTC)
- You're looking in the wrong place. You need to spend some time with tools like Google Scholar and Web of Knowledge to see what's in the academic journals. A search for "Boeing cockpit automation" in those places turns up dozens of relevant papers. --Robert Merkel 05:17, 6 April 2006 (UTC)
GRR... My upload bandwidth sucks...
I've noticed that anything that a ISP would sell you has a terrible up-down ratio (excluding SDSL, but that tends to have lower downspeeds). Where do the ISPs get all their bandwidth?--Frenchman113 19:19, 5 April 2006 (UTC)
- Er, this doesn't answer your question, but to my understanding the sum of up + down bandwidth is limited by the quality (i.e. price) of your and their DSL/cable equipment. Since most people are doing things like web browsing and email that don't upload much, the ISPs emphasize download speeds at the expense of the up. For completeness, the answer to what you actually asked is that ISPs rent bandwidth from bigger providers upstream of them (like UUNET) just like you rent it from them. Eventually you reach one of the backbone providers like Level 3 who own the biggest pipes and effectively "make" the bandwidth. --Tardis 20:37, 5 April 2006 (UTC)
- Right. But say one was feelthy rich and could lay one's own data link between continents. What would it take to become a 'Backbone' provider? Is the difference determined by who sells bandwidth to who? 08:31, 6 April 2006 (UTC)
- As to why upstream is slower: I like the picture in ADSL. That's just how frequency allocation has been made. To get a symmetric line: call your local telco providers, they are likely able to lease you a line. That is what most companies do when they want a high volume web site etc. Expect to pay 10x-100x what you pay for ADSL per month (more for really fat pipes). To lay your own lines: consult local legislation; you may need to form a company that is a certified telco provider. Sure that is possible if you have the cash; most telcos are private companies.
- For most home users the ADSL or cable modem the local telcos offer is pretty much the best price/speed point you can get. If there was a magical way to offer faster service some company would have already done that and wiped the competition off the Earth. Market economy in action... Weregerbil 11:06, 6 April 2006 (UTC)
From AIDS back to HIV
I was wondering if the drugs we have today for HIV patients are so good that they have the ability to make the HIV virus undetectable in the human body, they why can they not bring back a patients with AIDS back into HIV+ status?
- HIV+ is a different mode of operation of the virus -- a dormant phase with no symptoms whatsoever. I imagine that "undetectable" HIV is simply small numbers of viral particles, which can easily grow back to large numbers if the treatment is removed or becomes ineffective. In other words, HIV+ is a different kind of infection, whereas these drugs only change the amount of it (and not to 0). But I am not a pathologist at all... try reading the pharmacological information associated with the drugs? The FDA might have some relevant information. --Tardis 20:46, 5 April 2006 (UTC)
O4
Have molecules composed of four oxygen atoms been produced? What's up with them?
- In theory, one could have
O-O | | O-O
and fulfill the octet rule requirements. Cyclobutane has this structure (with hydrogens), for instance. But it strains this type of chemical bond to adopt a 90° angle, so it would almost certainly be unstable and fall apart into two normal O2 molecules. --Tardis 21:09, 5 April 2006 (UTC)
- Tetraoxygen does indeed exist at very high pressures. —Keenan Pepper 21:12, 5 April 2006 (UTC)
- There's N4 as well. I'm not sure anyone actually knows if O4 has a cyclic structure though. --BluePlatypus 23:31, 5 April 2006 (UTC)
- My proposition about O4 : since we know that O 2 is paramagnetic, before people can make the high magnetic field, it is anti-magnetic,why don't you try to make the experiment as follows:
- Use two tanks which can sustain a high pressure, a tank contain O2, another is empty, and maybe waccuum Join two tanks by one tube + one siphon + one tube ; ( siphon has the diameter bigger than the tubes); in middle of the siphon,place one thick steel frame which can sustain a high pressure, drill many pores( its diameter is super small as possible) on the steel frame , around the siphon, apply the highest magnetic field with about 60MOe, and then press the O2 in first tank thru the siphon, I think that you can get O4 in the second tank,this is my own opinion, I don't have any equipment for this experiment. If you have the condition to make it, please let me know the result. Or if you have the stuck, I have the time to suppose again . --User:Ngocthuan 06 23:08 , 6 April 2006 (UTC)
Galileo
My question is easy, but i just can't find answer :( What is the well-known phrase, associated with Gelileo Galilei? "Yet it spins", "Still it rotates" or how? Just i'm not native english speaker, and never interested of it in english. Thank you. ellol 21:48, 5 April 2006 (UTC)
- It's not mentioned explicitly in his article but it is linked in the 'see also' section. He was, apparently, forced to recant his heliocentrism, but muttered E pur si muove! - "And yet it moves" - under his breath. --Hughcharlesparker 22:08, 5 April 2006 (UTC)
- Sorry. Right. Thank you! ellol 03:24, 6 April 2006 (UTC)
- Yes, but this is most likely apocrophal. I mean, he might have said it under his breath (we really don't know), but he was effectively shut up about it. For great justice. 23:42, 5 April 2006 (UTC)
isotopes
the time it takes for one half of the amount of an isotope to decay to nonradioactive form is it's__________?
- Half-life = how much of my time I spend reading obvious homework questions. StuRat 08:23, 8 April 2006 (UTC)
Constitution font
On Mac OS X, is there a free font that evokes the kind of script used on old copies of the US constitution? It doesn't need to be exact, or historically accurate, but just evoke that kind of 'feel'. Thanks! For great justice. 23:36, 5 April 2006 (UTC)
- Zapfino is an incredibly flowing cursive font. It should be suitible for what you are doing. --Serie 00:06, 6 April 2006 (UTC)
Wooaaahh! That IS cursive! That's definately the puppy! Thanks! For great justice. 00:07, 6 April 2006 (UTC)
April 6
Adhesive bonding
I've asked a few questions on Talk:Adhesive without many satisfactory answers. I would like to know, for example, if I glue two pieces of polished steel with cyanoacrylate glue, how much of the bonding is chemical and how much is mechanical. I am inclined to think that it is largely a chemical bond, but if so, what is the bond involved? —Ben FrantzDale 02:59, 6 April 2006 (UTC)
- I don't think you could give an exact number for that. I'd think cyanoacrylates would mainly be considered to bond mechanically, polymer glues in general work by filling out the surface area while a liquid and then reacting to form a solid polymer. Chemical compounds in general don't bind very well to metal since the metallic bond is a bit of a different animal from most. It can still bind by chelating to the metal atoms on the surface, probably through either the cyanate or carboxyl groups. However, those bonds would be weaker than in the cases where an adhesive can form hydrogen bonds with the surface. --BluePlatypus 05:13, 6 April 2006 (UTC)
Photographic Memory
Although the eidetic memory page is certainly informative, I'm not quite clear on what answer is arrived at. Is there, or is there not, such a thing as photographic memory as it is commonly portrayed? By that I mean innate, photographic (actually a snapshot, rather than based around important features like 'red shirt' and 'a bit to the left'), essentially effortless, and durable. If not, why is there so much popular certainty that such people exist? Black Carrot 03:28, 6 April 2006 (UTC)
- This is from my own incredibly shaky memory, so may not be totally accurate, but from what I recall people actuallt do take in most of the items in a scene, but the linkage between short-term and long-term memory is better in some people than others; also some people are better able to retrieve items from their long term memory. It's not that some people have photographic memory where others don't; it's more that some people are better able ot store and access whatever memories they have received. Because some people can perform very well in such memory tasks, it is popularly assumed that some "super-special" memory is present in some individuals, shich is why the idea of photographic memory is so prevalent. Anyone able to confirm or deny...? My specialy was perception, not cognition :) Grutness...wha? 07:58, 6 April 2006 (UTC)
- On the off chance it jogs a memory, the only article I can remember ever reading that mentioned photographic memory existing claimed that, when people with such memory (which they apparently could get hold of enough of to do this test) forgot a picture, which did happen over time, it 'shattered' or 'fragmented' or some such rather than becoming vaguer and less detailed. Anyone recognize this? Black Carrot 04:27, 9 April 2006 (UTC)
The period validity of the patent
The period validity of the patent of the fuel saver by magnet treatment is invalid.Is’nt it ? Wiki? Ngocthuan 06 11:08, 6 April 2006
U.S. Patent 3,830,621 - Process and Apparatus for Effecting Efficient Combustion. U.S. Patent 4,188,296 - Fuel Combustion and Magnetizing Apparatus used therefor. U.S. Patent 4,461,262 - Fuel Treating Device. U.S. Patent 4,572,145 - Magnetic Fuel Line Device. U.S. Patent 5,124,045 - Permanent Magnetic Power Cell System for Treating Fuel Lines for More Efficient Combustion and Less Pollution. U.S. Patent 5,331,807 - Air Fuel Magnetizer. U.S. Patent 5,664,546 - Fuel Saving Device. U.S. Patent 5,671,719 - Fuel Activation Apparatus using Magnetic Body. U.S. Patent 5,829,420 - Electromagnetic Device for the Magnetic Treatment of Fuel.
I don't know the dates of these. For great justice. 04:27, 6 April 2006 (UTC) The Inset Fuel Stabilizer [10] appears not to be patented. For great justice. 04:29, 6 April 2006 (UTC)
It seems that we don't have articles on fuel saving gadgets, magnets round the fuel line or in the air flow (Ecoflow, FuelMAX, FuelSaverPro, etc), catalysts in the fuel line or tank (Broquet, Fitch Fuel Catalyst, Prozone, Fuelstar, etc), platinum-based combustion enhancers (PVI, Gasaver, Ctech3000, etc), ignition enhancers (Fuel Saving & Power Push, Fireball Ignition, etc, air bleed into the inlet manifold (Ecotek, Khaos, Powerjet USA, etc), turbulence increasers (Ecotek, Tornado Fuel Saver, Powerjet USA, SpiralMax, etc), devices to "atomise the fuel better" (Ecotek, Tornado, SpiralMax, Vaporate, etc), oil additives (Slick 50, Duralube, etc), fuel additives to enhance combustion (Acetone, PowerPill, BioPerformance, etc), engine "cleaning" products (10k Boost, Powerboost, etc), electrical modifications (grounding straps, voltage stabilisers, etc) or hydrogen generators. Shame. For great justice. 04:35, 6 April 2006 (UTC)
- In a slightly less oblique way, For Great Justice is suggesting that patent or no patent, the evidence that any of these devices actually work is extremely thin to nonexistent, particularly the ones related to magnets. See snake oil. --Robert Merkel 04:57, 6 April 2006 (UTC)
- Absolutely - although actually, I think an article on these devices wouldn't be a bad idea - explaining the science of why they can't work would be a worthwhile excercise. What would the name of the article be though? Is there a generic word for these? For great justice. 05:06, 6 April 2006 (UTC)
- Aside from "junk", I don't think so. To be fair, injector cleaners don't quite belong here, in certain specific circumstances they can actually be useful. Subaru actually recommends the periodic use of one for my Subaru Impreza WRX.
- But as to the broader point, how about fuel economy accessories, or something like it? A survey of the devices and their purported mechanisms of action would be quite useful. --Robert Merkel 05:11, 6 April 2006 (UTC)
- Fair point on injector cleaners. I still think there's some milage in the phenomenon of snake oil as applied to fuel economy magnets - perhaps only as a section of snake oil though. These aren't really just accessories though - the point is that they are completely spurious... For great justice. 05:18, 6 April 2006 (UTC)
- But as to the broader point, how about fuel economy accessories, or something like it? A survey of the devices and their purported mechanisms of action would be quite useful. --Robert Merkel 05:11, 6 April 2006 (UTC)
- I have been found out the magnet treatment around the fuel pipe from many years ago, but I think that it is the minimium magnetization, because it is very easy for locating the magnet lying perpendicular to another and first and foremost all of the magnets are perpendicularly to the fuel pipe, this thing is the same meaning that they cause the magnetic line perpendicular to the fuel pipe.
The magnetic Flux = B * S * cos (B,n) Here , cos (B, n) =0 ( n : the direction perpendicular to S; i.e: normal line of Surface S) For the maximum magnetization , cos (B,n) must be equal to 1
I.e.: the magnetic lines was caused by these magnets which are paralell to the fuel pipe.
For this raison, we can reduce the volume of the magnets, and follow to their weight shall be reduced noticeable . Another raison, many peoples don't like to use it,this is the interrelation of the dimension of the fuel pipe and the magnetic strength of the magnets. If the magnetic strength is so strong, the magnetized fuel molecules shall be hold to the fuel pipe, you can not run with the higher speed,you can open the throttle but the speed is holded at the certain value, it means the speed which is not increased. Many thanks for your time .Ngocthuan 06 16:25, 6 April 2006 (Vietnam)
Atmospheric pressure (can someone source this for me?)
An anon added the following to a (featured) page I watch: "Where an atmosphere is less than 0.006 Earth atmospheres water cannot exist in liquid form as the required atmospheric pressure, 4.56 mmHg (608 Pa), does not occur." I didn't see this specific point on the atmospheric pressure page and I don't know an mmHg from a bowling ball. Hoping someone could point to a source. Marskell 08:26, 6 April 2006 (UTC)
- It's the pressure at the Triple point of water. --BluePlatypus 08:33, 6 April 2006 (UTC)
red mercuy
Dear Sir is red mecury rs 99.999 can be used in medisence or not
- I believe the idea is, that if Red mercury existed (which it doesn't), it could be used in an atomic bomb. --BluePlatypus 08:35, 6 April 2006 (UTC)
- I think you are referring to mercurochrome which can be used as a topical antiseptic. - Cybergoth 03:21, 7 April 2006 (UTC)
Ewww, what the hell popped out of that earwig?
Hoping someone knowledgeable in earwig entomology can answer this. I just squished an earwig on the wall with a tissue. While pressing down on it (I had to squish it fast but it took a bit of finger-strength to get it to actually squish) there was a sound not unlike a clicking sound.
I take the tissue off the wall and there's two things -- the earwig's corpse, dead but intact. And then there was something else, it was a dark color and with a shape that an eggplant might be if you were to bend it in the middle 90 degrees. I'm guessing it was either something fecal or was it perhaps an egg it was carrying? Perhaps some inside body part of the earwig? Either way it convinced me that killing an earwig is an ickier experience than merely being in the presence of an earwig, and next time I'll capture one in a jar and let it loose in my neighbor's yard instead.
Just what in the world popped out of that earwig when I squished it? It wasn't even messy, just a solid object with no real "splatter" to it. --209.77.244.12 09:39, 6 April 2006 (UTC)
- I heard that earwigs have two penises in case one breaks off during sex. So maybe what you saw was its spare penis. Ah, our article on earwig has that fact as well. You might find some more stuff in that article that might help you. -- Daverocks (talk) 10:21, 6 April 2006 (UTC)
- The earwig article doesn't actually have a whole lot on earwig anatomy. Shame. For great justice. 18:00, 6 April 2006 (UTC)
- Also. WTF happened? Compact Flash cards are now the new standard for size comparison? Come on! Only on Slashdot, surely - what happened to a ruler, or something?! For great justice. 18:03, 6 April 2006 (UTC)
- The earwig article doesn't actually have a whole lot on earwig anatomy. Shame. For great justice. 18:00, 6 April 2006 (UTC)
Nuclear engineering
How is it possible to get highly enriched uranium from a centrifuge?Wont that Uranium possess critical mass and undergo fisson?What initiates criticality accidents?
- The uranium first goes through some processing which converts it to uranium hexafluoride. This is a gas, and its density is rather low compared to solid uranium, so criticality isn't so much of an issue here. --HappyCamper 11:16, 6 April 2006 (UTC)
- Have a look at Zippe-type centrifuge. The details of the various designs remain a closely-guarded secret. --Robert Merkel 23:17, 6 April 2006 (UTC)
El Nino and La Nina
Hello, I am writing an article for my high school newspaper about El Nino and La Nina because I read somewhere that we are just leaving a La Nina year and entering an El Nino year. Is this true, because the Wikipedia article doesn't say that. Thanks for your help!! Zach 10:42, 6 April 2006 (UTC)
- The Australian Bureau of Meteorology's climate page has extensive information about the current state of ENSO. --Robert Merkel 23:20, 6 April 2006 (UTC)
Mermaid
Hi,
Does mermaid exist?--Aju 11:07, 6 April 2006 (UTC)
- Try our article on mermaids. - Mgm|(talk) 12:40, 6 April 2006 (UTC)
Nope. How old are you? Loomis51 21:52, 6 April 2006 (UTC)
- Irrelevant. Misinformation can strike at any age, though generally we learn to guard against it better over time. Tzarius 09:07, 7 April 2006 (UTC)
To a very lonely sailor, a manatee can look like a mermaid. StuRat 08:14, 8 April 2006 (UTC)
Silicon Wafers
I've got a question about the surface of a silicon wafer. Do you get an silicon dioxide layer on the surface? If so, what kind of thickness might you expect? If not, what does the surface of a silicon wafer (outside of the cleanroom environment) look like? 12.106.14.201 14:36, 6 April 2006 (UTC)
- It looks pretty much like a (somewhat dark) mirror. Imagine this sliced up. You won't get an oxide layer at room temperature, you have to grow them at high temperature to the desired thickness. Current research involves MOSFET gate oxides with thickness < 10 nm. - mako 02:14, 7 April 2006 (UTC)
APOLOGY
Hello! It’s me Nita .I am going to write an assignment about Feasibility report.I am totally ignorant of this term. I had already sent a question to u n u people replied it too. I confessed that I had committed some mistakes that’s why I am sending you an informal apology .I beg your pardon sir,hope you will ignore my mistake. I admit it that my English is not proper but you people will have to accept the fact that on the face of this earth a lot of nations with different languages are residing and none can snub a person on the plea that he is speaking or writing wrong English .I know four languages .ENGLISH, URDU, HINDI, FRENCH and PERSIAN .I guess its enough for a girl who is just 17 .my purpose of sending u this mail is just to give u this explanation that ; I am sorry for using wrong grammar ,I am sorry for not saying PLEASE .now may you tell me what is feasibility report .I am not asking you to make my whole assignment I am just asking for a little assistance so that I may be able to fulfill my task properly —The preceding unsigned comment was added by 203.99.61.48 (talk • contribs) 14:37, 6 April 2006 (UTC) Thank you.
- When touring a strange land, it is best to have a guide, or to learn the local customs. That way, people won't be rude to you. Here, we have the equivalent of a guide at the beginning of this document, and it is best to read it. --Zeizmic 14:47, 6 April 2006 (UTC)
- A feasibility report describes whether something can be done or not, how easy or hard it will be to do, etc. Search for the term on google and you will find hundreds of examples of them. Chapuisat 14:52, 6 April 2006 (UTC)
- No, I don't think that's true. "Feasible" is different from "possible". For something to be feasible, it has to be something that can be reasonably accomplished within practical constraints, particularly economic ones; it's not enough for it to be possible in theory. That said, there is a minority usage which uses "feasible" synonymously with "possible" (makes my skin crawl, personally; it's as bad as "refute" meaning "deny"). But that usage is unlikely to be the one intended in something called a "feasibility report". --Trovatore 23:04, 6 April 2006 (UTC)
- Not sure why you think you're disagreeing with me. That's exactly what I was saying it was. "whether something can be done or not, how easy to hard it will be to do". So a report might come back and say "it can't be done" or it might say "It can be done but it will take 3 years and $400,000 and require extensive paperwork", or maybe "It will cost $0.75 and a trip to the hardware store". Anyways, the best way for the original poster to understand would be to google "feasibility report" and read through some examples. Chapuisat 13:33, 7 April 2006 (UTC)
- Huh? Saying it will take 3 years and $400,000 is information about how hard it is to do, not about whether it can be done or not. As far as I can see you're contradicting yourself in the space of two sentences. --Trovatore 19:59, 8 April 2006 (UTC)
- Whoops. My eye seems to have interpolated a "not" that wasn't there. I read it as "whether something can be done or not, not how easy or hard it will be to do. --Trovatore 20:22, 8 April 2006 (UTC)
- Huh? Saying it will take 3 years and $400,000 is information about how hard it is to do, not about whether it can be done or not. As far as I can see you're contradicting yourself in the space of two sentences. --Trovatore 19:59, 8 April 2006 (UTC)
- Not sure why you think you're disagreeing with me. That's exactly what I was saying it was. "whether something can be done or not, how easy to hard it will be to do". So a report might come back and say "it can't be done" or it might say "It can be done but it will take 3 years and $400,000 and require extensive paperwork", or maybe "It will cost $0.75 and a trip to the hardware store". Anyways, the best way for the original poster to understand would be to google "feasibility report" and read through some examples. Chapuisat 13:33, 7 April 2006 (UTC)
In the case of a feasibility report on an investment, an important indicator of how good the investment would be is the return on investment. This can either be given as a percentage or number of years. For example, if it costs a million dollars to build a bagel factory, and it can make 200,000 dollars in profit a year, that's a 20% ROI or 5 years to pay off the original investment. That would be considered to be a good investment. StuRat 08:09, 8 April 2006 (UTC)
Software to record data through the sound card
Does anyone know any piece of software to record everything that sounds through the speakers? Something like "redirecting" the data to a file. For MS Windows and GNU/Linux also, if possible. Thanks. --GTubio 14:58, 6 April 2006 (UTC)
- I know there's something for the Mac, and I'm sure there is for the PC or Linux, but don't know what it is - would Audacity meet your needs? For great justice. 17:24, 6 April 2006 (UTC)
- On windows, double click on the speaker icon, go to Options -> Properties, select the option "Recording" and on that list, enable all checkboxes that has something to do with "out" ("Stereo Out", "Mix Out", "Stereo Mix" or something like that). Click ok. The slide bars will change for recording volumes, and below each one there's a checkbox. Mark one of the outs and just hit record with any program, one of them will work. ☢ Ҡi∊ff⌇↯ 18:45, 6 April 2006 (UTC)
- The standard "low-tech" solution is to get a lead with 3.5mm stereo plugs on either end, plug one end into the output from your soundcard, and the other into your input or microphone socket. And then use Audacity to do the actual recording, as others have mentioned. Ojw 19:55, 6 April 2006 (UTC)
- On windows, double click on the speaker icon, go to Options -> Properties, select the option "Recording" and on that list, enable all checkboxes that has something to do with "out" ("Stereo Out", "Mix Out", "Stereo Mix" or something like that). Click ok. The slide bars will change for recording volumes, and below each one there's a checkbox. Mark one of the outs and just hit record with any program, one of them will work. ☢ Ҡi∊ff⌇↯ 18:45, 6 April 2006 (UTC)
Interconnection
If you connect a simple device designed for 240 V/ 50 Hz (like a British hairdryer) with an adapter to 110 V / 60 Hz (like America), will it work? Will the higher frequency damage it? 57.66.51.165 15:24, 6 April 2006 (UTC)
- No, it wont work....for a long time atleast.... The fuse will probably burn up..if it has a fuse... otherwise the whole device would blow up... :-D ..... Jayant,17 Years, India • contribs 16:05, 6 April 2006 (UTC)
- Well, you can get pretty cheap transformers that will convert the voltage. I have one, but frankly, if you only want a hairdrier, it would be cheaper to buy a small US hairdrier. For great justice. 17:21, 6 April 2006 (UTC)
- It won't work, but putting a 240V device in a 120V (the actual US voltage standard) does not, if I recall correctly, cause spectacular failure. The device just doesn't get enough voltage to do anything meaningful. Now, overvolting a 120V device in a 240V outlet... that will cause sparks to fly. As for frequency, damage is unlikely in either direction. — Lomn Talk 17:23, 6 April 2006 (UTC)
- If you plug a 60Hz device into a 50Hz socket, if it's got a transformer or coil somewhere in the circuit (most devices except incandescent light bulbs do), the lower frequency can cause the coil to saturate and become effectively a short circuit, quite possibly leading to a fire. --Serie 22:08, 6 April 2006 (UTC)
- Having moved around a lot between both sides of the Atlantic, I can confirm most of the above (haven't played much with frequency-sensitive stuff), but wanted to warn about transformers: firstly, they only convert voltage, not frequency, so a 120 -> 240 transformer used in the US will produce 240V 60Hz (not 240V 50Hz, like in Europe) electricity - be warned for frequency-sensitive appliances, they might well go wonky (basically, anything complex). Also, transformers have a maximum wattage rating - a small one might be 50W or 100W, check the label. While this is fine for most small appliances, be warned of anything that produces lots of heat (toaster, hairdryer...) - these use massive amounts of power (a medium-sized hairdryer is often 1000W, check the label), and these will blow your transformer in very short order. I agree with For Great Justice, get yourself one of those 'travel' hairdryers (often sold at airports) which have a voltage selector switch for 120 / 240. — QuantumEleven | (talk) 12:14, 7 April 2006 (UTC)
Orbital feasibility of Counter-Earth
According to the article the orbit of a Counter-Earth (a planet always on the other side of the sun from us) is just feasible. So would somebody please point out what is wrong with this analysis:
- Consider the earth at the point where the line joining it to the sun forms an exact right angle with the major axis of its orbit. Counter-earth must be at the opposite side of the sun, at the point where it's line to the sun also forms a right ngle with the elliptical axis.
- Now let us advance the earth until it is in the same position on the other side of the sun - i.e. the other point where it's line to the sun forms a right angle with the elliptic axis. In order for counter-earth to still be hidden it must now occupy the position that earth previously occupied. BUT this cannot be the case, because by Kepler's second law the areas swept by the arcs must be identical, and this is obviously not the case (one of the planets must be going round the long side of the ellipse).
- So is counter-earth orbitally feasible or not? DJ Clayworth 20:30, 6 April 2006 (UTC)
- Well, the counter-earth theory doesn't (or shouldn't) say that counter-earth is always 180° offset from Earth, but rather that it is so nearly so that it is permanently occluded by the sun. There's allowance for wiggle room in the orbit proportional to the apparent size of the sun. However, since counter-earth is effectively debunked by observations of other planets, I'm not going to bother to work out the math on this one. — Lomn Talk 21:04, 6 April 2006 (UTC)
- This was my first thought when seeing the problem above, however, as Melchoir pointed out, there is no requirement that Earth2TM needs to orbit on the same elipse. If the ellipse were rotated 180° for the other planet, then the instataneous velocities of the two would always be opposite and a line could be drawn connecting the planets and sun at each point in the orbit. So Kepler's Laws don't seem to prevent such a situation, but it's really a 3 body problem. The Lagrangian point article mentions L3 as a possible place for Counter-Earth, but doesn't say whether or not the system would be stable with two approximately equal masses. Maybe the maths reference desk would be able to help out? EricR 22:50, 6 April 2006 (UTC)
I think if the Hand of God were to place 2 perfect earth copies around a single sun, then it might be stable for a few million years. But instabilities, such as solar flares and giant meteors, would soon knock them out of perfect alignment. The formation of a Solar System is horribly unstable, and single planets sweep out their full orbital band. --Zeizmic 21:06, 6 April 2006 (UTC)
- Meteors schmeteors. The counter-earth would have to have a moon exactly the same size as ours, and at exactly the same distance from its primary, and at exactly the same point on its orbit as ours at all times, created at exactly the same moment - otherwise the two orbis would get out of synch very quickly. And given that the moon was most likely caused by a chance collision of a proto-planetary body with the earth, the chances of that happening are probably about as good as going down to the beach and finding a grain of sand with your name and address carved on it. Grutness...wha? 00:59, 7 April 2006 (UTC)
- And, as a final nail in the coffin, we have several satellites in solar orbit (mostly used for observing the sun), these would have spotted the Earth2TM already if it was there. — QuantumEleven | (talk) 12:07, 7 April 2006 (UTC)
- Ah, yes. It had not occurred to be that there was a different ellipse that might satisfy the conditions. And no, my question was not intended to imply I thought counter-earth might exist. Thanks for your help. DJ Clayworth 15:42, 7 April 2006 (UTC)
Lead and its history
I am doing a research a report about lead and am having trouble finding out about leads history. ANY information would be helpful.
- If you typed "lead" into the search box on the left of this page, you would have found our article on lead. --Robert Merkel 23:24, 6 April 2006 (UTC)
question on animal species
Out of all the animal species in the world, what animals are most abundant? The percentage?--24.147.235.177 21:57, 6 April 2006 (UTC)
- You mean the most individual animals or the greatest total mass? —Keenan Pepper 00:19, 7 April 2006 (UTC)
- It would be something small like ants or bacteria (though I can't remember if bacteria are part of the animal kingdom). - Mgm|(talk) 10:33, 7 April 2006 (UTC)
Journal Article
Where can I find the article: " On a supposed proof of a theorem in wave motion" which was written by G.J.Stoney, and published in the Philosophical Magazine in 1897 Vol.5 No.43? I am not sure if I will be able to find the place where your response will be posted, and I don't care if the whole world knows my e-mail address, I get lots of junk mail anyway. So if it's possible, send any information you find,to me at newage@uniserve.com Thank-you Thos
- Unfortunately, I can't find an online copy. (JSTOR doesn't have it.) Your only recourse might be to find a substantial university with an old collection. It's actually quite remarkable how many universities have these incredibly interesting historical journals in the open stacks. (Incidentally, be very gentle with the old documents if you do find the paper. Stuff from the turn of the last century may or may not be in good shape, depending on the paper and binding. You might want to ask for assistance from the library staff before you try to photocopy old bound journals—making copies can be very hard on their spines.) TenOfAllTrades(talk) 00:06, 7 April 2006 (UTC)
- Yeah, can't find it either. Its too old. -- Mac Davis] ⌇☢ ญƛ. 01:34, 7 April 2006 (UTC)
- I presume this is a US journal? If so, a copyright library might be your call of last resort. For great justice. 02:01, 7 April 2006 (UTC)
- If the homepage of the journal (here) doesn't have it (which it doesn't), then it's most likely not scanned or available anywhere at all online. Most journals don't have online archives that go back farther than a decade or two. Anyway, what you need to do is check with your local research/university libraries to see if they have it (their catalogs are usually online). If not, you can usually have a photocopy of the article sent to you from a library that does, for a small fee (say $5 or so). --BluePlatypus 04:50, 7 April 2006 (UTC)
- I can probably get you a copy of the article early next week, as my university seems to have it available pretty easily for scanning. Let me see what I can do. Also, the title of the magazine from that era was, to be specific, The London, Edinburgh and Dublin philosophical magazine and journal of science. What a mouthful. --Fastfission 12:13, 8 April 2006 (UTC)
Downloading the Yahoo! Toolbar
When I try to download the Yahoo! toolbar, I am led to the MSN Search engine site without my permission, and, of course, no download takes place. This happens no matter how many times I try again.
Here is the sequence of links
- http://toolbar.yahoo.com/config/slv4_page?.p=featureantispy&.cpdl=net06
- http://toolbar.yahoo.com/config/slv4_done?.act=3&.dflt=1&.intl=us&.region=us&.partner=none&.guest=&.cpdl=net06&.mf1=as&.xpsp2=1&.data=
- http://search.msn.com/results.aspx?q=us
Also, under the subject category of Science on the Wikipedia Reference Desk, the word computing looks like a hyperlink while "medicine" and the others don't. When I click on it, I go through the following sequence of links.
- http://search.globofind.com/search.php?q=computing-service
- http://yeahsearch.net/go2.php?data=26jIHcbbwh32dJicop6wjyAIKfWgl7r01cAKDyEORq3OEb6Bv333IqkZxMIadqYKLJShLXjHtcRNTbpN+UWUsVwNIXaeMZgi6cOwHja4vMFRNAR9b2QeJ0kxQQInv74YIulcDWoCAPkqrbTD6QMQrbDQuuBbH98tX085VaCNQUdYqbWJSwUrgrrGuSowsFUa8GXtTCZW41D+Q2Irm20v8pSlKc8lvXf58Q0vgucaRBYfOWo1jfjAfFlh0A3JfvGH8y2uzZx0XzsR3zVVrodwcdHornJLKLCTdPxyQpV7ZxiWr%2FxERnwK8UfLwK5jmzBls80fxsSSXn4PU8Ay2boYgzLqKVsfbihnyDJpWdIeV3X3RD96lQkn+aaCuQJwCdZ30Fn9fIPKZoVeshYoZIlEKPkM49IHtC3FNZSzHy%2F6KihhWyUVXwi8nrQGe56G6XLv4tPp1L03jqrRDz5ARDmMNd9Hvew2zH2ZJ9no9+5pTlGg8aRUxcTWlXfDodSunhRPIoAtr26yWTnwYuYll+Ni76z9IOcoOmWcnx3ZYj9ZmIl4xOve1+nRQu9CYvuNA2TfQ7jmDhRZ3jr7dRDEXWf1Vp%2FfmRcc04q3&an=3
- http://www.google.com/
- Many other links on Wikipedia take me to global find in search of something. I have a Windows XP Media Center Edition. I have scanned my computer with the latest version of Norton Anti-virus and found nothing. I have also updated my Windows operating system. I was going to download the Yahoo! toolbar to use its anti-spyware software, but I can't do it.
Can someone help me? When previewing this page, even words that I haven't created links for on the edit page have links after I click "Show preview."Patchouli 22:07, 6 April 2006 (UTC)
- ok it looks like you probably have some sort of spyware? first off, i wouldnt bother with the yahoo toolbar, its not going to help anything. go into start->control panel->add/remove programs. look for anything that might be spyware and get rid of it (get rid of viewpoint media player- your spyware is a bit more malicious than that though, so its gotta be some other stuff). download lavasoft adware, install it, get the latest patch inside the program, and run it, delete what it finds. now go download mozilla firefox for your browser... alot of the spyware that targets internet explorer doesnt affect firefox. if you are still having a lot of spyware problems after these 3 steps, there is a simple solution to it all. backup your desktop, my documents, and any other personal data you have, and reinstall windows. modesty 02:50, 7 April 2006 (UTC)
- I have Ad-aware and have run and deleted everything twice today. Do you think uninstalling Internet Explorer and reinstalling it will help? I can't find IE in the Add/Remove program list.Patchouli 03:10, 7 April 2006 (UTC)
- I obtained a resolution after calling 1-800-HP-INVENT. Here is what I did.
- I opened Internet Explorer.
- I clicked on the Tools menu.
- I chose Internet Options.
- I clicked on the Advanced tab.
- I removed the check mark next to “Enable third-party browser extensions (requires restart)" under the Browsing section.
- Then I clicked OK, closed the browser, disconnected, and restarted my computer.
- I obtained a resolution after calling 1-800-HP-INVENT. Here is what I did.
This was the panacea to all my browsing and file-downloading issues. Patchouli 05:03, 7 April 2006 (UTC)
I suspect that this problem originated when I visited Matt's Today in History.Patchouli 06:03, 7 April 2006 (UTC)
- It sounds as if this turned off some co-operative adware. Nevertheless, the idea of some unsolicited program in my computer fills me with dread. When I had a hint of this the other day, I immediately disconnected the machine from the internet, formatted the hard disk, reinstalled the system and applications, and then restored my personal data (not programs) from last night's backup. I would recommend you do the same. If you aren't willing to, at least never enter any financial data or important password on this machine, ever again. Notinasnaid 12:16, 7 April 2006 (UTC)
- i know how you feel but remember if you browse in fear you are letting the terrorists win!!! modesty 16:23, 7 April 2006 (UTC)
It's 8 times easier to catch something with IE than Firefox. The troubles with my kids went down to nothing when I converted everybody. Apparently, even 'good' sites are being hijacked and filled with exploits. --Zeizmic 15:52, 7 April 2006 (UTC)
- The Mozilla browser works well only for some time. If you want to keep it permanently, I believe you have to pay $30 for it.
If you visit Matt's Today in History, you will see that about five windows pop up asking you whether you want to run Active X-Controls, and the only option is to click the OK button. On my last visit, I used the Windows Task Manager to end close the Matt's window entirely along with the pop-ups.
- Currently, everything is fine; however, except the Standard Buttons and Address Bar, all of my toolbars are gone. Can a computer expert go to Matt's site to investigate this issue and come up with the solution short of reinstalling Windows? (I warn computer neophytes like myself not to go to http://wwww.mattstodayinhistory.blogspot.com/.)Patchouli 23:39, 7 April 2006 (UTC)
Webmail
How long has G-mail been an experiment? How long does it take? My university give me this ridiculous 2 Mb inbox limit and delete things without notice if you go over (I've checked, and I can't see how I could possibly over the limit). I'm fed up of it, and since Opera wont let me download IMAP mail (what in the world could make this more difficult than downloading POP email which it allows), I need to find an alternative. Can anyone recommend a service that isn't going to try to charge me to download email or whatever? Another thing that sickens me, is when they say they've "unfortunately" (yeah, right; they "unfortunately" want to extort money out of me) had to reserve the ability to download email or use email clients to paying customers only. Email services should be free, like the sun, the air or the daffodils planted by the council.
Since Google insist on increasing their pledge to users to ludicrously high capacities when they could be opening up 250 Mb accounts to everyone, I pledge to never use their stupid email service as long as I live (or until I forget). --Username132 (talk) 23:50, 6 April 2006 (UTC)
- And those "ludicrously high capacity accounts" are open to everyone too. Just find someone with Gmail and ask them to send you an invite. - Mgm|(talk) 10:35, 7 April 2006 (UTC)
- Apart from the privacy issues, Gmail sounds like it could fit your needs, check out Yahoo as well though. BTW, someone pays for those daffodils, most likely through taxes, and someone pays for free email, somehow, sometimes by showing you ads, sometimes by using the info in your emails to better show you ads. You might want to think seriously about what the cost of your 'free' email is. For great justice. 00:17, 7 April 2006 (UTC)
- Mozilla Thunderbird (website) can download IMAP mail, if that helps. It's completely free, too, and has a ton of other great features. -- Daverocks (talk) 07:27, 7 April 2006 (UTC)
- Note that Gmail are playing a bit of a statistical shell game with their claimed capacity. AIUI, they're working on the principle that the vast majority of people aren't going to use anywhere near as much as they've got available, so they can say that the maximum you can have is very high. Couple this with the fact that they are buying more and more disks all the time and you have the basis of the claim. If everybody suddenly "filled" their Gmail mailbox the servers would collapse in a gibbering heap. (Or, more likely, the allowed capacity would drop very quickly until you'd suddenly met it.) --Bth 11:26, 7 April 2006 (UTC)
- If you want to keep your school's "free" email (how much of your tuition money is going towards those 2Mbs?), then I'd go with Daverock's solution and get Thunderbird. A mail client will allow you to use your own hard drive as your email's space, and so you could certainly fit 250 MBs or whatever you need. I'm not sure I understand your anger at Gmail, though. It is indeed open to everybody, they just liked the viral marketing strategy they went with. If you'd like an account, just email me or check out any of the Gmail spoolers that are now chock-full of invitations. But like FGJ pointed out, there's no such thing as a free lunch. — Asbestos | Talk (RFC) 13:52, 7 April 2006 (UTC)
Relative Velocity
Given that a person standing still on earth would nonetheless be moving at several thousand kph due to the earth's rotation, and given that this velocity would only be exponentionally increased by the Earth's revolution around the sun, and given the massive speed at which our solar system revolves around the centre of the milky way, and finally, given the milky way's incomprehensible speed in which it drifts away from the centre of the universe, is it possible to estimate the relative speed at which we're actually moving? If so what is it, and how close is it indeed to the speed of light? Loomis51 23:55, 6 April 2006 (UTC)
- There is no "center of the universe," although one can sensibly establish a "universal" reference frame based on the frame in which the surface of last scattering of the cosmic microwave background is stationary. It turns out we're moving at about 0.2% of the speed of light, or about 600 kilometers per second [11], relative to that. -- SCZenz 00:01, 7 April 2006 (UTC)
- Wow, interesting. I was about to say the question made no sense but your answer's better. Isn't the surface of last scattering expanding, though? So it's not really stationary in any reference frame, just expanding equally in all directions. —Keenan Pepper 00:07, 7 April 2006 (UTC)
- The "surface of last scattering" I believe means the surface at which the CMB last scattered (on average) at the time when it scattered. Thus it's a specifically-defined surface in both space and time. Yes, if you trace the CMB into the present day, obviously it's being spread out in all directions, so you can think of the speed I gave as (in rough terms) our speed measured relative to the average "rest frame" of the CMB near the earth (where the expansion of the universe has little effect). All this was determined based on the measured dipole of the CMB, as is indicated in the reference I added above. -- SCZenz 00:10, 7 April 2006 (UTC)
- I also read here that the major source of this movement may be the Local Group of galaxies orbiting the Virgo cluster of galaxies. -- SCZenz 00:13, 7 April 2006 (UTC)
- Relative velocity is the velocity of the body, this body interacts to another nearby it , as the earth gravity attracts a man, a man drives round the lake by car, the route of the lake is a curve line.
- But all of the surveys of motion always observe based on a nearest object , as a man and earth, and the interaction still exist (i.e.: the gravity extraction). Relative velocity can use to compare something which estimates motionless, when you use the term of relative velocity in this case, it is exactly . But if you can win the gravity extraction, it means you leave the earth into univerve, the relative velocity is not the notion which is applied for discussion. Here, the power is enough to win the earth gravity, it already issues the initial velocity , and from here, when you go slowly, it means your initial velocity is reduced some value which is you must register for your itinerary(or you have to use the formula : v(t)= a v(t)+ v ini ) …
- Ngocthuan 06 08:59 2006-04-07 (UTC)
- I'm not sure I follow your argument; can you clarify? -- SCZenz 20:25, 7 April 2006 (UTC)
April 7
Brake Fluid and Clorox
Hi. i was reading an email when it mentioned something about if you mixed Brake Fluid and Clorox it would make smoke.i was wondering if it would make smoke.if not, is there any other household stuff that when mixed will make smoke?(i like pyrotechnic stuff..)
Thanks, --Shannon 00:46, 8 April 2006 (UTC)
- I'm not sure about the brake fluid and bleach, but a Google search will yield some results, such as this. In redox reactions like this, there is an oxidizer and a fuel source to be oxidized. There are too many of these chemicals to list them all, but in the example I gave you above, potassium nitrate is the oxidizer and sugar is the fuel.--Chris 01:12, 7 April 2006 (UTC)
Thanks.do u know where exactly i can get potassium nitrate from?
- There is no way to get it easily from household items. It must be purchased specifically. I recommend ScienceLab.com. Please be sure to review the MSDS for potassium nitrate before deciding to work with KNO3. I don't suggest that go ahead with this "experiment" if you do not plan to follow proper safety precautions and have some sense of responsibility. Please follow all directions exactly as they are stated and use your good judgement.--Chris 03:28, 7 April 2006 (UTC)
You might also find it in the local hardware store as 'Stump Remover', where you are supposed to soak the stump in it, let it dry, and then light it. Never worked for me. --Zeizmic 11:56, 7 April 2006 (UTC)
- I thought stump remover is straightup black powder, which does have KNO3 in it, plus charcoal and sulfur. --Chris 22:41, 7 April 2006 (UTC)
Hmmm. i will try to find the chemicals and all safety precautions will be observed. Thanks for helpin me find the answer to it =)
--Shannon 00:45, 8 April 2006 (UTC)
Is sleep deprivation good for anything?
I'm often very tired, and don't have time to get an adequate amount of rest. I'm wondering, is there anything good about sleep deprivation? Flea110 04:22, 7 April 2006 (UTC)
- Well, according to sleep deprivation, it seems that in amongst all the bad things it can do, low sleep levels might help fight depression... temporarily. Seems like the depression usually comes right back after a normal amount of sleep, though. -- Filliam H Muffman 05:10, 7 April 2006 (UTC)
- After 36 hours or so you start hallucinating. GangofOne 07:24, 7 April 2006 (UTC)
- As this PubMed article suggests, sleep deprivation increases serotonergic activity in the brain, which temporarily relieves psychological disorders such as depression. As a person with social anxiety disorder (which is also linked to low serotonin levels), I can confirm that this is true from experience. You should note, however, that you will only get a noticable effect if you have a chemical imbalance in the first place. Oh, and of course eye candy hallucinations are also encountered with sleep deprivation, although I wouldn't describe them as pleasant. --Aramգուտանգ 08:30, 7 April 2006 (UTC)
- I agree entirely with aram's comments, and for exactly the same reason. I would add, though, that some artists have used the hallucinations associated with sleep deprivation to good purpose - most famously Salvador Dalí. Grutness...wha? 10:37, 7 April 2006 (UTC)
- I doubt that. I've been up for 36-48 hours straight quite a few times, and never ever had a hallucination. You can get flashes in front of your eyes, but I wouldn't call that a "hallucination". A migraine can give you that too. --BluePlatypus 15:15, 7 April 2006 (UTC)
- Someone here's an outlier then. I've definitely had hallucinations from that sort of length of sleep deprivation (though mine were auditory -- water in pipes seeming like voices, that sort of thing). --Bth 16:02, 7 April 2006 (UTC)
- i heard radiohead frontman thom yorke would use sleep derivation sometimes when writing lyrics modesty 16:20, 7 April 2006 (UTC)
Sleep deprivation helps me get work done, as I get too tired to be anxious, and my anxiety contributes significantly to procrastination. moink 21:26, 7 April 2006 (UTC)
Space-Time Curvature under General Relativity
This is a question about how non-scientific explanations of the Theory of General Relativity are supposed to explain gravitation. Layman explanations of space-time curvature usually have a diagram (apparently always the same one) which shows a two-dimensional surface streched (downwards) into a third dimension at the ___location of a body having mass. The story goes that a second body going by with no acceleration will follow a curved path because space-time is curved by the first body.
What I don't understand is why this would cause one body to curve towards another rather than away. When I try to figure out what the curved path will actually be (from the diagram), it looks like the it should curve away. Apparently, it is implied that the second body would fall into the 'depression' in the original two-dimensional surface because of.... what? the influence of gravity? It's apparently using gravity to explain gravitation. How is this explanation supposed to work? The Wikipedia article hints it's not a simplistic as the picture, but doesn't seem to go beyond that.
- If someone is able to post a complete and thorough reply to this question, please forward it to the Nobel Prize committee. Seriously, though, the curved sheet model just takes advantage of the fact that objects rolling around on a big sheet in a 1 G field happen to move in a way similar to what general relativity predicts for objects moving past planets and the like. It's meant to show you how things move, not why things move. To really understand why things move, you will have to understand nasty things like metric tensors and the Einstein field equations. -- Filliam H Muffman 07:24, 7 April 2006 (UTC)
- Well.. I don't quite see why you'd think it would curve away. If you have a downward "dimple" in a tablecloth or similar and roll a ball towards it, moving in a straight line, it will go around the rim in a curved path once it hits the dimple and continue away in a straight line in a different direction, having been deflected somewhat inwards. That analogy is the point of the picture. If the dimple was raised instead of lowered, then it would be deflected in the opposite, outwards, direction. But gravity doesn't act in that direction, which is why you've got a lowered dimple and not a raised one in the picture. --BluePlatypus 07:54, 7 April 2006 (UTC)
- The diagram also gives a nice visual analogy for the inverse square law, since the gradiant of the curve is much steeper near the object than far away. But like the others have said, this is a way of visualizing how the objects would move so, not why. — Asbestos | Talk (RFC) 13:36, 7 April 2006 (UTC)
- In other words, it's just a cool picture? It's describing the exactly the same behaviour as Newtonian gravitation. Peter Grey
Sports Science
How can the diet of a body builder be compared to the diet of a jockey?
- In many ways. You could compare the number of calories, or the proportion of carbohydrates, or even the sheer weight of the two diets. Grutness...wha? 10:35, 7 April 2006 (UTC)
It's probably a polite fiction that people can significantly bulk up without an Anabolic steroid. Just compare the body builders of yesteryear with the Rambo's of today. --Zeizmic 14:52, 7 April 2006 (UTC)
- It's definitely possible. Depends what your goal for bulk is, but with enough protein and exercise, one can add major muscle mass without resorting to drugs. You may not end up looking like the hulk, but rambo is in reach, given the right genes. Night Gyr 17:35, 7 April 2006 (UTC)
Time dilation
What is the easiest way to understand length contraction and time dilation?
- Here on Wikipedia, a good starting point might be our Introduction to Special Relativity page, which takes a fairly unusual but (IMO) particularly clear geometrical approach. For more details, try our articles on length contraction and time dilation. Elsewhere online, sites like this and this take the more common playing-ping-pong-on-a-train approach. Do come back here if you have anything you want cleared up. --Bth 11:20, 7 April 2006 (UTC)
Create a super computer by many used computers
I hear that we can create a super computer by many used computer, it means that If I have about 10 pcs of Pentium III Pc, I can create one super computer. The Operating System now is open source.User: Ngocthuan 06 2006-04-7 19:52 UTC
- If you had looked at the supercomputer article, you could have probably seen Beowulf (computing), which is the standard model for making a supercomputer cluster. The links and external links in that article will probably tell you most of what you're looking for. — Asbestos | Talk (RFC) 13:19, 7 April 2006 (UTC)
Logical way to finish this Sudoku?
I got annoyed with the Sudoku today because it took me more than 2-3 stops on the T to solve, so now I've decided that it was a bad puzzle (obviously). I solved the puzzle by supposing one box was one number, working through it all and seeing that it didn't lead to any contradictions. My question is: Was there a logical way to finish this sudoku, without starting with "Suppose this box is a ...", and then showing presence or absence of a contradiction? I realize that that is an ok way of finishing a tough sudoku, but I far prefer it when they can be solved more elegantly:
7 2| 6 | 98 5 |928| 71 98 |74 | 2 ----------- 6 8|29 | 17 273|156|849 19 | 87|2 6 ----------- 3 |872|964 427|639|185 869| 1 |723
Thanks! — Asbestos | Talk (RFC) 13:16, 7 April 2006 (UTC)
- Probably not, the puzzle looks like it's been designed with the "pick one of two choices and see if it leads to a contradiction" method in mind. Parts of it can be solved independently, though: for eample, one of the two possible choices for filling the central square leads to a fairly obvious contradiction in the central columns. —Ilmari Karonen (talk) 17:12, 7 April 2006 (UTC)
- I'd agree, I can't see a way to do it that doesn't rely on guesswork^W proof by contradiction. As such, it doesn't count as a well-formed sudoku to my way of thinking. --Bth 17:18, 7 April 2006 (UTC)
- All solutions depend on proving-by-contradiction. Some of the problems just have more obvious contradictions, making it easier to find the correct one. It's an NP-complete problem, so one solution isn't really much more elgant than the other since they all more or less imply testing all the possibilities. So the perceived elegance is more about whether you can solve it within your mental 'search depth', or whether you have to resort to writing the numbers down. --BluePlatypus 18:23, 7 April 2006 (UTC)
- I see what you mean, but solving using the various other "standard" techniques (listed at length in our sudoku article) doesn't feel like guesswork/proof-by-contradiction in the way that having to employ the "what-if" method does. I've never seen a sudoku before that had to be solved by what-if. (OTOH, I've often solved them by that and then used my knowledge of the solution to see what I'd missed in my application of the other techniques.) --Bth 18:54, 7 April 2006 (UTC)
- Well, yes and no. Personally I feel that a sudoku should be solvable by deduction in that you should logically be able to deduce simply by examining the puzzle what particular number will go into a space. If you are left with a situation where the only way of finding out is to plug in numbers and see whether the correct solution can be reached you've gone beyond deductive reasoning and into inductive reasoning - a different matter entirely, my dear Watson. Grutness...wha? 03:41, 8 April 2006 (UTC)
- I see what you mean, but solving using the various other "standard" techniques (listed at length in our sudoku article) doesn't feel like guesswork/proof-by-contradiction in the way that having to employ the "what-if" method does. I've never seen a sudoku before that had to be solved by what-if. (OTOH, I've often solved them by that and then used my knowledge of the solution to see what I'd missed in my application of the other techniques.) --Bth 18:54, 7 April 2006 (UTC)
Desktop & Laptop screen placement
1)In a desktop, the monitor is more or less perpendicular to the desk, and we view that monitor with 3 feet distance. If we use a laptop or a tablet pc whose screen is placed at 45 degrees to the desk/lap, should the same distance of 3 feet be maintained? Or simply, if viewing angle changes, should there be a difference in viewing distance?
2)What is the reccommended viewing distance and reccommended angle for placing laptop screens?
When we place the screen on the laps in a slate tablet PC, the viewing distance is 1 to 1.5 feet. Does that say that viewing distance is related to angle of viewing?
- Laptops and tablets are not particularly ergonomic. Get an external keyboard and jack your laptop up on some phone directories when you are using it as a desktop replacement. For great justice. 18:38, 7 April 2006 (UTC)
- You can get stands that hold the laptop screen vertically at eye level (the ones we use do so by having a 30° tray to put the laptop base-part on, with the hinge furthest away from you) and plug in an external keyboard and mouse. Ojw 20:36, 8 April 2006 (UTC)
- Your screen is probably not at a 45 degree angle; many laptops are barely even capable of bending that far. Night Gyr 06:29, 9 April 2006 (UTC)
Can Envelopes Be Composted?
Paper can be recycled or composted but envelopes cannot be recycled due to the glue. Can envelopes (without plastic windows) be composted? --Username132 (talk) 15:16, 7 April 2006 (UTC)
- Theoretically, most things can be, but consult your local recycling company for their facilities / policies on this. For great justice. 18:36, 7 April 2006 (UTC)
- I'm sorry - you said composted, not recycled! They will certainly break down if you put them in a composter - the question is, not knowing exactly what chemicals are in it, you might not want to use the compost on vegetables etc you want to eat - otherwise, go for it. For great justice. 22:24, 7 April 2006 (UTC)
Dr. Keith Black neurosurgeon
Why is there no information on Kieth Black M.D. on wikipedia ?
- Because no one has added anything about him yet. I didn't know who you were talking about so I looked him up. He doesn't seem terribly notable to me, but if you feel like adding information about him, go ahead. Be Bold. Chapuisat 16:55, 7 April 2006 (UTC)
- He seems sufficiently notable to me to warrant an article (and to displace the drag-racing Keith Black to a disambig link), so I've created a stub for him based on a quick Google search; I'd strongly encourage the questioner to add some info if they have any. More generally, to expand on Chapuisat's point, Wikipedia has gaps and omissions because it's entirely the result of volunteer contributions and constitutes a permanent work in progress. --Bth 17:00, 7 April 2006 (UTC)
- If one added every living and dead physician, lawyer, and dentist, then we would have maybe over 10,000,000 articles on these folks alone. Unless that person made a breakthrough and accomplished something meaningful, I don't think such articles would be needed.Patchouli 23:54, 7 April 2006 (UTC)
Linux
From a Linux tutorial; "Most modern Linux distributions encourage a practice in which each user has a specific directory for the programs he/she personally uses. This directory is called bin and is a subdirectory of your home directory."
Would it not be inefficient for many users to have different copies of the same program? --Username132 (talk) 16:42, 7 April 2006 (UTC)
- Well, if it's a big multi-user system, each user probably has a disk quota that they can use to store whatever they want. If the programs they want to run aren't available in /usr/bin or /usr/local/bin or whatever, they can put them in /home/whoever/bin. —Keenan Pepper 17:07, 7 April 2006 (UTC)
- And the particular situation of everyone having a local copy of SuperWhizzyUtilityX shouldn't arise if the sysadmin's on the ball. They should be putting anything that several users want into /usr/bin and such places. (Incidentally, if you want to see where the shell searches for executables when interpreting command lines, type "echo $PATH" to see the (colon-separated) list stored in the PATH environment variable.) --Bth 17:15, 7 April 2006 (UTC)
Gold in sea water
I have read somewhere that there is approximately 9 tonnes of gold per km cubed in sea water. --
-Is this true for all seas (apart from where there is large amounts of fresh meltwater)?
-Is the same true for fresh water and what is the amounts?
-Is the gold not worth anything (like industrial diamonds)?
-Is there an efficient/cost effective way of extracting this gold, taking into account; positioning (what sea/ocean), labour, building/machienry etc.
-If you discover anything "good" please don't make it "exceptionately clear" to anyone else and put it on the website. I cant force you to but pretty please do.
Im slightly mad but if it wil work i will be slightly rich....Yipee!!!
I think im ment to do this: --William Dady 16:58, 7 April 2006 (UTC)
- The presence of trace amounts of gold and other precious metals in seawater is not a secret, and it is not economically feasible to extract it because the concentration is so low. 9 tonnes may seem like a lot, but a cubic kilometer is a ridiculous amount of water. See [12] and Fritz Haber, a brilliant chemist who tried and failed. —Keenan Pepper 17:12, 7 April 2006 (UTC)
- To put it into perspective, a cubic km of water weighs about a trillion (1,000,000,000,000) kg, or a billion metric tonnes. So you got a concentration in the 9 parts per billion (mass) (by your numbers).
- The 1st billion tonnes is the hardest. --GraemeL (talk) 23:39, 7 April 2006 (UTC)
- Thanks for your query. We figured it out but sorry we're not sharing. alteripse 14:59, 8 April 2006 (UTC)
Centrifugal Force
If a space station were to have a ring with people inside and it was spinning fast enough then it should create artificial gravity. So my question is if a person inside this ring where to jum up would he or she be pulled down to the spot where the jumped up from? Patrick Kreidt
- Essentially, yes. You should draw a force diagram of the situation you are talking about. I think you are interested in whether the ring would 'spin' under the person while they were in the air? Sketching out a diagram will show that there are no forces that will do this in the example you mention. For great justice. 18:34, 7 April 2006 (UTC)
- I don't think so. Maybe I have not thought this completely out, but here is how I see it. At the time a person jumps 'up' (and 'up' is defined as perpendicular to the surface) a person will be moving forward at a certain speed. Ignoring air friction the person will continue to move forward at the same speed the floor is moveing forward. Since the floor moves in a circle and the person does not, for the person to come down in the same place would require the floor to travel a longer distance in the same time the person requires to land. From this I conclude the person will land in a spot a little ahead of the take-off point.
- Why doesn't the person move in a circle? As the ring spins, it emparts momentum to the person at an angle tengental to circle, that means they spin, with the ring, and are pushed away from the center of rotation. If the person jumps towards the center of the ring, they already have momentum emparted by the ring that will carry them 'forward' at the same rate that the ring is spinning. For great justice. 20:49, 7 April 2006 (UTC)
OK - so take a look at the diagradm - the black arrow shows the force vector of the spinning ring. The red arrow the direction of spin, and the green arrow the arc of the jumping man. Because he has the same forward motion as the ring, the arc he describes, even if he jumps 'up', will put him back where he began. For great justice. 21:06, 7 April 2006 (UTC)
- That's roughly true, but remember that the ring moves in a circle, whereas the person's initial velocity (aside from the "jumping speed") is tangential to the circle at the time of the jump. I think you land in roughly the same place, for small jumps, but getting an exact answer requires actually calculating it out. -- SCZenz 21:21, 7 April 2006 (UTC)
- Er, I don't think it quite works like that. You have to remember that there's no force 'down' (outward) on the jumping man, just whatever residual momentum he carried when he left the ring.
- Picture the following situation. The ring sits in the plane of this webpage, like this: → O
- The ring rotates counterclockwise. The top of the ring is moving left (←) and the bottom is moving right (→).
- Our hypothetical spaceman is standing on the inner surface of the rotating ring. Assume that we conduct our experiment just as he reaches the bottom of the circle. He, and the ring, are both going to be moving to the right (→) with equal speed.
- The spaceman jumps. He retains the original horizontal component of his speed → and adds a modest upward component (↑), assuming he pushes off normal to the ring surface. The path he follows will then be straight along the vector sum of those two components, taking him diagonally up and to the right on our diagram until he smacks into the wall again (er, lands).
- So, what happens? Let's follow the spot of ring from which our spaceman started. Its horizontal velocity will be
- vhoriz(t) = vmax·cos(ω·t)
- where positive velocity is to the right. In other words, its velocity is at a maximum at the bottom of the circle, and decreases as the centrifuge turns.
- Our spaceman, on the other hand, retains all of his initial horizontal velocity, so he lands ahead of his starting point. TenOfAllTrades(talk) 21:21, 7 April 2006 (UTC)
- Hmmm...looking at that explanation, I think I can cut it down a bit by looking at the problem in a slightly different way.
- The launch point on the ring travels at constant speed along a curved path.
- The astronaut travels at a constant speed greater than the speed of the ring surface (remember the vector addition of his jump velocity to the ring's velocity) along a straight path.
- The two paths intersect at some point after the jump.
- The astronaut gets there first — he followed a straight path at higher speed. Therefore, the astronaut will land at a point on the ring ahead of his departure point. TenOfAllTrades(talk) 21:26, 7 April 2006 (UTC)
- So, my diagram is wrong, because the spaceman describes a straight line, not a parabola? For great justice. 21:30, 7 April 2006 (UTC)
- Huh. Thanks, that'll teach people to trust anything that they read on the internet! So, why does this not work on earth, which looks like the opposite case? For great justice. 21:27, 7 April 2006 (UTC)
- I think it does work on earth, but the difference is so small it can be ignored. Keep in mind, on Earth you will only be jumping maybe 3 feet, on a ball with a 4000 mile radius. I will try to explain, though. Remember that circumferance increases in direct proportion to the radius. This means the arc of a circle with 4000mi radius will be slighty shorter than the same number of degrees of arc of a circle with 4000mi+3feet radius. This means your jumper will have to move a longer distance in the same time the earth does to traverse the same arc.
- How about this version? For earth, actually I think the difference is that you do describe an arc, not a line, because gravity is continually acting on you - no? For great justice. 21:34, 7 April 2006 (UTC)
- I think it does work on earth, but the difference is so small it can be ignored. Keep in mind, on Earth you will only be jumping maybe 3 feet, on a ball with a 4000 mile radius. I will try to explain, though. Remember that circumferance increases in direct proportion to the radius. This means the arc of a circle with 4000mi radius will be slighty shorter than the same number of degrees of arc of a circle with 4000mi+3feet radius. This means your jumper will have to move a longer distance in the same time the earth does to traverse the same arc.
- The Earth case is quite a bit more complicated due to gravity, yes. Where you land (ahead or behind your starting point) depends on the size of the centrifuge and speed of rotation (note that it has to be fast enough that you don't fall off when you go over the top....) as well as the impulse you give yourself during your jump. In the special case where you jump while the centrifuge is at the bottom center (as described in my first though experiment above), you'll land ahead of your jumping off point—it comes down to the person maintaining a constant horizontal velocity while the jumping off point is losing the horizontal component of its velocity. I'm too tired to work through the consequences for anywhere else on the centrifuge right now. TenOfAllTrades(talk) 03:41, 8 April 2006 (UTC)
- The easiest way to figure out the direction of these effects, and their approximate magnitude, is to pretend the Earth (or other spinning body) is actually at rest, but apply the Coriolis force. --Trovatore 16:40, 8 April 2006 (UTC)
Chemical structure formula in Word?
Does anyone know of any (free) application able to draw chemical structure formulas and save them into the WMF or EMF format, so that they can be inserted in for instance Microsoft Word? --Andreas Rejbrand 18:39, 7 April 2006 (UTC)
- You might try ChemSketch.[13] There's a free version, but I'm not sure what file formats it can save in. ChemDraw can save in those file formats, but there aren't any free versions, as far as I know. --Ed (Edgar181) 18:47, 7 April 2006 (UTC)
- Thanks; I'll have a look at it. --Andreas Rejbrand 18:49, 7 April 2006 (UTC)
- Now I've tested it, and it really looks great. Thank you for informing me, Edgar181. --Andreas Rejbrand 19:12, 7 April 2006 (UTC)
Total human decomposition in Canada
A tall order, I know, but I was wondering how long it would take a human body to totally decompose in a four-season (with a "real" winter, which is to say at least one or two months below zero degrees Celsius) environment.
I've read up on decomposition and eco-cemeteries (the latter being the reason I'm interested in the question), but neither go into enough detail to really tell me how long, pillar to post, it takes before a body is entirely gone. Skeleton included.
I'm aware that there are factors like ground moisture, limestone, etc. involved, but a ballpark-by-decade would be great. 10 years? 20? 60? Thanks! --MattShepherd 20:13, 7 April 2006 (UTC)
I'm no expert but i know the ___location where you bury the body really matters, they've found human skeletons and even bodies still fully formed (in admitedly extreme conditions) that are hundreds of thousand of years old.
- The tricky part is the skeleton, which generally requires salt-water or something rather caustic to break it down. The rest is broken down fairly easily, unless there is some extreme condition in which microbes can not exist. StuRat 07:57, 8 April 2006 (UTC)
- Skeletons can remain for ages in good conditions. Your best bet would be to contact the Body Farm in Tenessee, but you'd better explain why you want to know to them... - Mgm|(talk) 19:40, 8 April 2006 (UTC)
what if..
if every single human being on the face of the earth decided to jump 1 foot to the right, at the exact same time would it be enough force in one direction to shift the earths orbit? tilt? tidal forces? register on a ricter scale?21:13, 7 April 2006 (UTC)
- The Straight Dope answers the question for the specific case of China - seems like not much would happen. [14]. Answerbag has another demonstration of why this is bogus [15]. For great justice. 21:17, 7 April 2006 (UTC)
- nah thers no way, but i mean if you do think about it, every particle in your body is exerting gravity on everything... all the time modesty 03:58, 8 April 2006 (UTC)
- I think this is an example of the falacy of equivalence of large numbers. The earth is really big, and the number of people on it times their weight is really big. Therefore they are equivalent, and one will automatically effect the other. For great justice. 22:19, 8 April 2006 (UTC)
- nah thers no way, but i mean if you do think about it, every particle in your body is exerting gravity on everything... all the time modesty 03:58, 8 April 2006 (UTC)
Why does DNA only replicate in the 5' - 3' direction and not vice versa?
I know this is kind of a homework question and you guys don't like that which is fair enough, but i'm revising for my degree and really have no idea why. I am generally quite interested anyway. Cheers, Mark west 80.42.104.21 22:23, 7 April 2006 (UTC)
- I believe it is because the enzyme that catalyses the the replication process can only grip on the "5" end of a strain. Since it can't start at the "3" end, 3-5 replication does not happen. Note that this is from my sketchy memory of biochemistry 5 years ago. SanderJK 23:27, 7 April 2006 (UTC)
- WRT homework questions, there's no problem with asking specific factual questions (like yours seems to be, though it's an area I know nothing about). What we object to is when people post an essay topic, or a physics homework problem, or the like, and expect us to do the task for them in its entirety. --Robert Merkel 00:28, 8 April 2006 (UTC)
What is the alloy grade of cast steel which used for cylinder head?
In low speed diesel engine, the cylinder head is Manufactured from cast steel. Please, I need to know the alloy grade of cast steel and the folloing properties: 1- denisty 2- specific heat 3- thermal conductivity
thank you
- That's a toughie. You might have to ask a manufacturer of low-speed diesels like MTU to find out - or get a hold of a sample and take it off to the metallurgy lab. If you're interested because you want to set up in competion to them, the latter might be your only option. --Robert Merkel 00:35, 8 April 2006 (UTC)
April 8
Electrical Storms
Why do electrical storms only seem to occur in a rainstorm, but never in a snowstorm? Loomis51 00:19, 8 April 2006 (UTC)
It's possible to see lightning in a snowstorm. I saw it several times in New Hampshire. Brian G. Crawford 01:10, 8 April 2006 (UTC)
- See the environmental lapse rate page. A thunderstorm derives some of its energy from air rising in an unstable atmosphere, and moisture condensing as it cools. Warmer air on the bottom can hold more moisture and is more unstable than cooler air. EricR 01:55, 8 April 2006 (UTC)
Also, does lightning strike in the sea, and if so does anything special happen compared to striking land? --Username132 (talk) 01:28, 8 April 2006 (UTC)
Lightning in a snowstorm is referred to as thundersnow, and we had it here this winter. Night Gyr 03:27, 8 April 2006 (UTC)
It depends a lot on other factors, probably - such as the ___location of the storm, wind currents, etc etc etc. Here in southern New Zealand, for instance, thunderstorms are almost always accompanied by hail rather than rain. And yes, lightning quite often strikes over the sea (where I live I've got a great view over the Pacific), with no obviously spectacular results. Grutness...wha? 04:37, 8 April 2006 (UTC)
Oxidizing Heavy Metals Salts
I would like to know in details about the oxidizing heavy-metal salts as this relates to corrosion of copper and copper alloys. Copper alloys resist many saline solutions, alkaline solutions, and organic chemicals. However, copper is susceptible to more rapid attack in oxidizing acids, oxidizing heavy-metal salts, sulfur, ammonia (NH3), and some sulfur and NH3 compounds.
We have a corrosion problem in one of our gas engines of Caterpillar and the service engineer identified the occurance of oxidizing heavy-metal salts on a engine part made of copper alloy.
I would appreciate your helping me out of this situation by providing details obout oxidizing heavy-metal salts.
Thanks & Regards,
Ahmed Mohiuddin Caltex Oil (Pakistan) Limited A chevron Company
- The obvious answer is to replace the copper with something less reactive, like gold or platinum. Another option would be to supply a "sacrificial rod", say made out of aluminum or magnesium, which would react with the heavy metal salts in place of the copper. The rod would need to be replaced as it corrodes, of course. One option might be to place the rod in the oil reservoir. Hopefully, the oil will carry the salts to the rod before they can attack the copper. The rod could be attached to the oil cap, but must be long enough to extend down into the oil in all conditions. Water heaters often use a sacrificial rod. StuRat 07:28, 8 April 2006 (UTC)
- You may be looking for the article on sacrificial anode. TenOfAllTrades(talk) 14:28, 8 April 2006 (UTC)
Adobe Photoshop Album Starter Edition 3.0
okay....im really starting to get mad at my Adobe Photoshop Album Starter Edition 3.0 because every time i go to a website any pictures that are on the site are automatically saved to it. Does anyone know how to stop it from doing this?I dont even have to look at the picture specifically...it just automatically saves it....really annoying.
Thanks for any help,
Shannon 03:15, 8 April 2006 (UTC)
This is NOT a science question. Ohanian 04:46, 8 April 2006 (UTC)
- No, but it's a computer question. I don't know the software, but look for a preferences tab on programs icon bar, failing that, what do you use it for? Why not uninstal it and use a free image editor like The Gimp? For great justice. 06:49, 8 April 2006 (UTC)
okay ill do that thanks.
Shannon 01:14, 9 April 2006 (UTC)
What is hafnium's cosmic history?
What is hafnium's cosmic history? I've looked everywhere I think I could find that information, but I can't seem to get any information that I need. Could you help me find the information I need, please?
- What do you mean by "cosmic history"? The only thing I can think of is how it was originally formed, which it shares in common with all the heavier elements, so I don't understand why hafnium has been singled out. You may want to look at our article on nucleosynthesis for more on that. --Bth 07:12, 8 April 2006 (UTC)
Ear ringing
My ears ring when I have earplugs in, I read in the wikipedia article that theres no cure for it, but I was wondering if this was normal, and if there was anything I could do to make them stop ringing, thanks.
Flents
- I have used Flents foam ear plugs which I have learned reduce ringing more than any other type of earplug. However, after wearing earplugs for over six hours every day for some time, I noticed that the ringing sound stayed even after I took the earplugs out of my ears; this is tinnitus. I my case, it ceased after I stopped putting earplugs in my ears for a month. Try to use the earplugs only if it is necessary.Patchouli 09:44, 8 April 2006 (UTC)
Not enough sleep...
having "black lower eyelids" (i don't know its real name) has always been frustrating to many people. i always wonder why they appear when we don't get enough sleep, and perhaps there might be some other reasons?... i would be more than grateful if you could just stop by and answer this question for me. Thx! --219.77.165.58 11:18, 8 April 2006 (UTC)
- The skin around the eye (especially directly under it) is extremely thin and has a lot of blood vessels in it. While you are awake, your eyes stay open most of the time and you get a buildup of gunk (wax, dust, salt, etc...) in your eye. Tears help keep it clean, but they work best at night with your eyes closed and with plenty of REM. That buildup does two things - pushes blood vessels closer to the surface of the skin and blocks flow, making the vessels expand slightly. The more visible vessels are what you are seeing when you see shadows (and puffiness) under you eyes. --Kainaw (talk) 16:49, 8 April 2006 (UTC)
genius v.s. lunatics
many great mathematitians and well known scientist have the tendency of being nuts, but why is that? Thx :)
- A simple answer to your question is that people who are capable of making brilliant new developments (in any field whether it's math, science, philosophy, etc.) tend to be people that think differently than others, that look at problems in a new way, or don't simply accept the traditional point of view. Society tends to think of people with that kind of outlook as nuts (or at least "eccentric" in polite company). --Ed (Edgar181) 11:42, 8 April 2006 (UTC)
- I'm also fairly sure that the genius/lunatic thing is incorrect. In my recollection, there is no correlation between true mental illness and intelligence, but the cases in which they do correlate are generally so interesting and noteworthy that we end up letting them dominate our perception of it. --Fastfission 12:07, 8 April 2006 (UTC)
- I'd agree with both statements, and would like to add the fact that from my runins with various scientists i would say that many fields tend to attract certain kind of people, and that the studying of some fields can really change your view of the world. Combined with a certain social ineptness that does seem more common among researchers then in most circles, and the relatively often portrail of autistic savant in popular media, and the fact that abnormal people (including scientists) will get more media attention in general, it is easy to understand how such a picture of scientists would become widespread. Most of all, they are just people, perhaps with a little workaholic nature engrained. SanderJK 13:00, 8 April 2006 (UTC)
My cynical hemisphere will bet it's 99% a matter of noticing. Ordinary person has mental illness-- no news. "Brilliant" mathematician (is there any other kind?) or scientist has mental illness, and everybody can feel reassured that they are better off and savor the irony of the smarter guy's misfortune. Eccentricity and poor social skills are usually distinguishable from major mental illness. (what is the dsm-iv for "nuts," anyway?) alteripse 14:56, 8 April 2006 (UTC)
- In the case of a "genius", poor social skills and a constant preoccupation are what others call "mental illness". As an example, Einstein has terrible people skills. After his wife died, he became a shut-in. When in public, he either did his obligatory presentation or stayed away from the crowd, preoccupied with other things. Over and over, the genius form of antisocial behaviour has been explained as a disdain for the stupidity of humans in general. Einstein's quote, if I remember correctly, is that "Only two things are infinite, space and human stupidity. I'm not sure about the former." As for the preoccupation, they are working on problems that they find much more interesting than what to have for dinner or which politician do we want to raise our taxes next year. All in all, I see it as an adult trying to fit in with a class of preschool children. The children aren't really stupid, they are normal. The adult isn't mentally ill either. They are just focused on different things. --Kainaw (talk) 16:44, 8 April 2006 (UTC)
- OTOH, a large part of Einsteins 'genius' status is the fact that he fit so well into the stereotype. I'd say he was a large part of defining it. By comparison, Bertrand Russell for instance, shared a similarily negative view of humanity but was quite social. Given the political activism of both, it's quite obvious that they weren't actually disinterested in humanity itself. All in all, I think the 'insane genius' myth says more about people in general than about the geniuses. First, it displays our need for 'heroes', placing some people on pedestals way above everyone else, even though they're actually just at one end of a continuum. (Einstein was a genius, but was Niels Bohr? Feynman? Gell-Mann? Weinberg? Aage Bohr? Any Nobel-prize winner? Etc) Second, it illustrates a human tendency for 'justice'. People who are very smart must somehow 'pay' for that by having diminished ability in other areas. So geniuses are anti-social. Athletes are stupid. Etc. Sure, there are lots of 'geniuses' who were single-minded and anti-social, but there are those people on any job that doesn't require those skills. And as Alteripse said, there's a big difference between eccentric behaviour and real mental illness. Another factor might be cranks - people might reason along the lines of a crackpot simply being a genius who's wrong or misunderstood. (that's certainly how they see themselves!) A lot of them do seem to have some form of personality disorder, and they also seem to have a rather homogenous set of personality traits. (dogmatism, delusions of grandeur) But those personality traits aren't the ones that make a good scientist in the real-world. --BluePlatypus 20:40, 8 April 2006 (UTC)
- As a friend of mine likes to say: "The line between genius and insanity is very thin. In Mexico, we call it the Rio Grande." Grutness...wha? 01:25, 9 April 2006 (UTC)
- Someone asked me once whether I suffered from being crazy. I replied that I don't suffer, I love every minute of it. Of course, that was a quote from someone so I can't say I actually made it up, but it demonstrates a distinct lack of feeling by most people towards those who are different. I would never think I suffer from being like I am (ie. a crazy scientist :-) ), but others would instantly think that because they could never like my situation that I mustn't like it myself. Ansell 01:25, 9 April 2006 (UTC)
- I think your comment demonstrates a certain lack of feeling towards those who have a genuine mental disorder. Many of them do suffer, profoundly. --BluePlatypus 03:50, 9 April 2006 (UTC)
- :-D I was speaking with tongue in cheek of course. Ansell 03:59, 9 April 2006 (UTC)
dynamic programming
how to implement dynamic programming using 'c' language — Preceding unsigned comment added by 59.92.34.98 (talk)
- Our article on dynamic programming is quite general; the ideas should be readily applicable to C. --Bth 14:27, 8 April 2006 (UTC)
C# Adding Machine
Please can someone give me the code required to make an adding machine in Microsoft Visual Studio C sharp 2005 express edition? Computerjoe's talk 12:53, 8 April 2006 (UTC)
- sounds like a homework question. have you tried asking your classmates? Night Gyr 19:18, 8 April 2006 (UTC)
- No, it's not a homework question. I'm a good faith editor, and I know this isn't the place to get h/w done. I'm learning C# by myself, and have made an adding machine before; but forgot the code. Computerjoe's talk 21:06, 8 April 2006 (UTC)
- wouldn't it just be a matter of creating code for each button, so pushing a key puts a number-symbol onto the end of a string, then when an operation key is pushed the string is converted to a number and the specified operation is performed? it doesn't seem to hard to write if you know how to create button controls. I know java and C/C++, not C#, though, so microsoft may be pulling something different. Night Gyr 05:56, 9 April 2006 (UTC)
Poincare's radiation paradoxes
Hey folks! I was just reading Olivier Darrigol's paper from the journal Isis on the Einstein-Poincare priority dispute, and I came across the phrase "radiation paradoxes" as an item of importance. What are these radiation paradoxes? I'm a layman, so I was hoping someone could explain it in ordinary english. Thanks in advance! 65.95.139.89 18:49, 8 April 2006 (UTC)
- The very short version is that if you try to work out the equations of electromagnetism -- particularly for the propagation of electromagnetic radiation (ie light) -- for different observers travelling at different speeds, but use Galilean relativity (that is, the intuitive idea that the speed of an object moving at according to one observer is according to another observer in whose reference frame the first observer is moving at ) you will get different answers for different observers -- hence "radiation paradoxes". Postulating an invariant speed of light fixes this, but forces you to use a more complicated equation for relative speeds (albeit one that is very close to the Galilean one at low speeds). --Bth 19:26, 8 April 2006 (UTC)
Diseases
How many diseases affect the man most and the woman most? — Preceding unsigned comment added by 70.53.95.183 (talk)
- Red/Green Colorblindness is overwhelmingly male, since it is caused by a recessive gene on the X chromosome, of which women have 2 but man have 1 (They have XY instead of XX). 21:14, 8 April 2006 (UTC)
- I'm not sure how to answer this question. Men, for example, are incapable of contracting cervical cancer. And with regards to "how many", you can't really say "six" as an answer. Could you rephrase? Isopropyl
- Isopropyl is right; for more examples, see also Sex and illness. Melchoir 22:40, 8 April 2006 (UTC)
Data compression?
I was wondering, are there any lossy text compression algorithms? he he... it would be a bit like censorship if you think about it.--Frenchman113 21:12, 8 April 2006 (UTC)
- Ys, thr prbbl r sm lss txt cmprssn lgrthms. --GraemeL (talk) 21:16, 8 April 2006 (UTC)
- Pitman shorthand is another one. Four candles, anyone? --Heron 21:31, 8 April 2006 (UTC)
- A lossy text compression system wouldn't be very much use, but if you wanted to play, you could run text through an mp3 or jpg compression system, and see what came out - the results would probably show you why there really isn't one in the sense you mean it. For great justice. 22:04, 8 April 2006 (UTC)
- Pitman shorthand is another one. Four candles, anyone? --Heron 21:31, 8 April 2006 (UTC)
- you could use abbrev. to repr. words. They lose some data (i.e. gain ambiguity) but as long as context makes up for it, you can save space at min. qual. loss--same prin. as other lossy algos. Night Gyr 06:01, 9 April 2006 (UTC)
Another question
Hate to be a nuisance, but how can I force WMP to save video that's being streamed from the web? I'm totally missing something here...--Frenchman113 22:31, 8 April 2006 (UTC)
Projectile, Missile, and Rocket
What is the difference among these?Patchouli 23:15, 8 April 2006 (UTC)
- A projectile is any object launched into the air by any given power source (includes asteroids, arrows, cannoballs, meteors, etc). A missile is a projectile launched by a human (in the modern sense, usually an explosive-bearing rocket). A rocket is a device powered by Newton's third law of motion (exhaust=action, rocket movement=reaction). Hope that helps.--Frenchman113 00:02, 9 April 2006 (UTC)
- In a general sense, a missile is a general term encompassing all human-launched projectiles, including stones flung from slings and shells from battleship cannons, but in a modern military context, it's the subset of rockets that have their own guidance systems, i.e. guided missiles. Night Gyr 06:04, 9 April 2006 (UTC)
April 9
latex in xfig diagrams
I'm trying to make a diagram in xfig which includes some LaTeX formatted text. I'm following the instructions here.
Here's what I do:
- draw my diagram
- make a text box with text "$\int f(x)\, dx$"
- set the "special" flag to "special" of the text box
- choose export, then select "combined PDF/Latex both parts", then export, resulting in two files intbox_t and intbox
- change the filename of intbox to intbox.pdf; my system won't work without the extension
- change the line "\includegraphics{intbox}%" to "\includegraphics{intbox.pdf}%", so account for the change in filename above
- in my tex source file, I include the header "\usepackage{graphicx}"
- I input the file with "\input intbox3.pdftex_t"
- then I tell latex to do its work. It seems to find the file and import the pdf, but then it barfs with:
loading : Context Support Macros / PDF (2004.03.26)
) (./intbox3.pdftex_t <intbox3.pdf, id=1, 258.9675pt x 177.66376pt>
<use intbox3.pdf>
! Undefined control sequence.
\color ...vevmode \csname fi\endcsname }\@ldc@l@r
l.14 }}}}
?
I'm using an OSX system, using TeXshop frontend to pdflatex.
I'm a hair away from giving up. This is for a wikipedia article, so if you can straighten this out for me, you're helping grow an article. -lethe talk + 00:23, 9 April 2006 (UTC)
- Are you using \input{intbox3.pdftex_t}? If you want to email me the sources I could have a look. I use TeTeX under Linux but it doesn't seem to be an operating system problem. Ansell 00:54, 9 April 2006 (UTC)
LASIK and losing vision
I overheard someone saying that you lose part of your vision or something like that when you have LASIK surgery, is this true?
- Our article on LASIK might be helpful to you, in particular the Complications section. -- Daverocks (talk) 02:53, 9 April 2006 (UTC)
BMW Bluetooth
I have a BMW with bluetooth, and I had the code but I lost it. BMW says they dont have it and want $120 to retreive it from my car, is there any other way to get it? I used to use a motorola v600 and the code is in the phone, I just cant retreive it (I dont know how), how can I get the code?
Cloning
Is it possible at this time to produce a clone of someone?
- I think so, yes. According to the article on human cloning, ACT was the first to sucessfully clone a human embryo. There are many claims of success beyond the embryo stage, but none of them have been verified. --Bowlhover 04:54, 9 April 2006 (UTC)
How accurate are the Heavens Above predictions?
In terms of time, how accurate are the Iridium flare predictions? I know my latitude, longitude, and elevation to within 30 m, so the errors in my position shouldn't affect the results too much.
I'm curious about this because I plan on photographing tomorrow night's magnitude -2 flare, using a 15-second exposure time. I'm going to use an accurate clock to tell me when to press the shutter button--there needs to be 7.5 seconds of exposure before maximum brightness, and 7.5 seconds after. --Bowlhover 04:42, 9 April 2006 (UTC)
Tinted CD-Rs
I saw and purchased some tinted CD-Rs yesterday in Taipei. The writing surface of these discs is in bright orange or bright green (they are colored like highlighter marker pens) and they cost NTD6 each (less than US$0.20 cheap). Do they employ newer dyes? Or are they just ordinary CD-Rs with tinted polycarbonate plastics? -- Toytoy 07:15, 9 April 2006 (UTC)