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[[Image:MAXIMA_Balloon.jpg|right|thumb|250px|Il pallone Maxima pronto per il lancio]]
=[[en:Bulbous corpuscle]]=
L<nowiki>'</nowiki>esperimento '''MAXIMA (Millimeter Anisotropy eXperiment IMaging Array)'''<ref>{{cite web | title = Comunicato stampa del MAXIMA | publisher = UC Berkeley | date = 2000-04-09 | url = http://cosmology.berkeley.edu/group/cmb/press_release.html | accessdate = 9 febbraio 2009}}</ref> è stato un esperimento finanziato da [[Stati Uniti d'America]], [[National Science Foundation]], [[NASA]] e il [[dipartimento dell'Energia degli Stati Uniti]], e operata da una collaborazione internazionale capeggiata dall<nowiki>'</nowiki>[[Università della California]].
Lo scopo di questo esperimento è stato la misurazione delle fluttuazioni della [[radiazione cosmica di fondo]].
Tale esperimento è stato realizzato compiendo due voli di un pallone da alta quota, l'[[agosto]] del [[1998]] e [[giugno]] del [[1999]]. Entrambi i voli sono partiti dalla [[Columbia Scientific Balloon Facility]], situata a [[Palestine (Texas)|Palestine]], [[Texas]]. Tali palloni hanno sorvolato la Terra ad un'altitudine di 40000 metri per otto ore. Il primo volo ha preso dati dallo 0,3 % circa della porzione nord del cielo, vicino alla [[Dragone (costellazione)|costellazione del Dragone]]. Il secondo volo, chiamato anche MAXIMA-II, ha scansionato la porzione di cielo in direzione dell<nowiki>'</nowiki>[[Orsa Maggiore]].
=[[Corpuscolo di Ruffini]]=
Inizialmente pianificato assieme all<nowiki>'</nowiki> [[esperimento BOOMERanG]], è stato rinviato per ridurre i rischi riducendo il tempo di volo, nonchè per permetterne il lancio e l'atterraggio in territorio Statunitense.
{{anatomia
==Strumentazione==
|Nome=Corpuscolo di Ruffini
[[Image:MAXIMA Cyro.jpg|left|thumb|180px|Maxima's Feedhorns and Bolometers]]
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|Didascalia=Terminazioni nervose del corpuscolo di Ruffini
|Sviluppo embriologico=
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|Arteria=
|Vena=
|Nervo=
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Il '''corpuscolo di Ruffini''' è una classe di [[meccanorecettore|meccanorecettori]] ad adattamento lento. Si pensa che siano presenti solo nelle zone naturalmente glabre del [[derma]] (dorso della [[mano]], pianta del [[Piede (anatomia)|piede]], [[labbro|labbra]], [[piccole labbra]] e [[glande]]), e nell'[[ipoderma]] umano. Il nome deriva dal medico italiano [[Angelo Ruffini]].
==Function==
This spindle-shaped receptor is sensitive to skin stretch, and contributes to the kinesthetic sense of and control of finger position and movement.<ref>{{Cita libro|cognome=Mountcastle |nome=Vernon C. |anno=2005 |titolo=The Sensory Hand: Neural Mechanisms of Somatic Sensation |editore=Harvard University Press |p=34}}</ref> It is believed to be useful for monitoring slippage of objects along the surface of the skin, allowing modulation of grip on an object.
Ruffinian endings are located in the deep layers of the skin, and register mechanical deformation within joints, more specifically angle change, with a specificity of up to 2 degrees, as well as continuous pressure states.They also act as a thermoreceptors that respond for a long time, so in case of deep burn there will be no pain as these receptors will be burned off.<ref>{{Cita libro|cognome=Hamilton |nome=Nancy |anno=2008 |titolo=Kinesiology: Scientific Basis of Human Motion |editore=McGraw-Hill |pp=76–7}}</ref>
==Footnotes and references==
==Instrumentation==
[[Image:MAXIMA Cyro.jpg|left|thumb|180px|Maxima's Feedhorns and Bolometers]]
A 1.3-metre primary mirror, along with a smaller secondary and tertiary mirror, was used to focus the microwaves onto the [[feed horn]]s. The feed horns have spectral bands centred at 150, 240 and 420 GHz with a resolution of 10 arcminutes. A [[bolometer]] array consisting of 16 NTD-Ge Thermistors measured the incident radiation.
The detector array was cooled down to 100 mK via a four stage refrigeration process. Liquid nitrogen cooled the outer layer of radiation shielding and He-4 was used to cool the two other layers down to a temperature of 2-3 K. Finally liquid He-3 cooled the array down to operation temperature.
The shielding, together with the properties of the feed horns, gave a superb sensitivity of 40 μV/sec^1/2.
Two [[Charge coupled device|CCD]] cameras where used to provide accurate measurements of the telescope's orientation. The first wide-field camera pointed towards [[Polaris]] and gave a coarse orientation up to 15 arcminutes. The other camera was mounted in the primary focus and gives an accuracy of 0.5' for stars brighter than 6th magnitude, which in total gives an accurate position tracking of 10' for the telescope and hence of the microwaves.
For pointing the telescope, four motors were used.
==Results==
[[Image:MAXIMA_Map.png|right|thumb|200px|MAXIMA CMB fluctuations map]]
Compared to MAXIMA's competitor the [[BOOMERanG experiment]], MAXIMA's data covers a smaller part of the sky but with much more detail. By the end of the year 2000 the experiment provided the most accurate measurements of the [[cosmic background radiation]] (CMB) fluctuations on small angular scales. With this data it is possible to calculate the first three acoustic peaks from the [[cosmic background radiation|CMB]] power spectrum. These greatly confirm the standard cosmological model by measuring a baryon density of about 4%, which agrees with the density calculated from [[Big Bang nucleosynthesis]]. The measurement of the [[shape of the Universe|flatness of the Universe]] also confirms a major prediction of [[cosmic inflation|inflationary cosmology]], although BOOMERang was the first to discover this.
==References==
==See also==
* [[Cosmic microwave background experiments]]
* [[Observational cosmology]]
==External links==
* {{Cita pubblicazione|autore= Paré M, Behets C, Cornu O |titolo= Paucity of presumptive ruffini corpuscles in the index finger pad of humans. |rivista= J Comp Neurol |volume= 456 |numero= 3 |pp= 260–6 |anno= 2003 | pmid = 12528190 | doi = 10.1002/cne.10519}}
[http://cosmology.berkeley.edu/group/cmb/ Homepage of MAXIMA]
<nowiki>
[[Category:Sensory receptors]]
[[cs:Ruffiniho tělísko]]
{{CMB experiments}}
[[de:Ruffini-Körperchen]]
[[es:Corpúsculos de Ruffini]]
[[fr:Corpuscule de Ruffini]]
[[gl:Corpúsculo de Ruffini]]
[[he:גופיף רפיני]]
[[pl:Ciałka Ruffiniego]]
[[pt:Corpúsculo de Ruffini]]</nowiki>
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