unreferenced date April 2011 Aperturesynthesis or synthesis imaging is a type of interferometry that mixes ... astronomy observations. Technical issues Aperturesynthesis is possible only if both the amplitude ... at once, and can give high quality images. Differences Image Earth rotation aperture synthesis.jpg thumb 300px Most aperturesynthesis interferometers use the rotation of the Earth to increase the number .... Most aperturesynthesis interferometers use the rotation of the Earth to increase the number of different ... array instead of Earth rotation, such as in Aperture Masking Interferometry aperture masking interferometry . History Aperturesynthesis imaging was first developed at radio wavelengths ... aperturesynthesis to create a One Mile and later a 5 km effective aperture using the One .... Aperturesynthesis is also used by a type of radar system known as synthetic aperture radar , and even ... from a conventional telescope with an aperture diameter equal to the maximum baseline, hence the name aperturesynthesis . It was rapidly discovered that in many cases useful images could be made ..., using powerful but computationally expensive algorithms. Other wavelengths Aperturesynthesis imaging has been demonstrated in the optical and infrared, first using aperture masking interferometry and later ... have released aperturesynthesis images Cambridge Optical ApertureSynthesis Telescope COAST , Navy ... Light field External links http www.webcitation.org 5kmnhRe25 Further details of aperturesynthesis ... telescopes coast Cambridge Optical ApertureSynthesis Telescope radio astronomy Category Radio telescopes ..., a very demanding technology which became possible only in the 1990s. This is why imaging with aperturesynthesis has been used successfully in radio astronomy since the 1950s and in optical infrared ... algorithms such as the maximum entropy method . The alternative name synthesis imaging acknowledges the shift in emphasis from trying to synthesise the complete aperture allowing image reconstruction ... more details
COAST , the Cambridge Optical ApertureSynthesis Telescope , is a multi element optical astronomical interferometer with baselines of up to 100 metres, which uses aperturesynthesis to observe stars with angular resolution as high as one thousandth of one arcsecond producing images with much higher resolution than can be obtained using individual telescopes such as the Hubble Space Telescope . The principal limitation is that COAST can only image bright star s. COAST was the first long baseline interferometer to obtain high resolution images of the surfaces of stars other than our sun although the surfaces of other stars had previously been imaged at lower resolution using Aperture Masking Interferometry on the William Herschel Telescope . The COAST array was conceived by John E. Baldwin , and is operated by the Cavendish Astrophysics Group . It is situated at the Mullard Radio Astronomy Observatory in Cambridgeshire , England . External links http www.mrao.cam.ac.uk telescopes coast COAST http www.mrao.cam.ac.uk telescopes coast astronomy.html Some of the first high resolution optical images of the surfaces of distant stars obtained using COAST and the William Herschel Telescope http maps.google.com maps?q Cambridge&t k&hl en&ll 52.163966,0.040544&spn 0.001343,0.005987 Google maps image with COAST at the center coord 52.1640 0.0405 type landmark source enwiki googlemaplink display title Category Telescopes Category Interferometric telescopes Category Cavendish Laboratory observatory stub de Cambridge Optical ApertureSynthesis Telescope it Cambridge Optical ApertureSynthesis Telescope zh ... more details
Microwave Imaging Radiometer with ApertureSynthesis MIRAS is the major instrument on the Soil Moisture and Ocean Salinity satellite SMOS . MIRAS is a planar antenna composed of a central body the so called hub and three telescoping, deployable arms, in total 69 receivers on the Unit. Each receiver is composed of one LICEF module, which detects radiation in the microwave L band , both in horizontal and vertical polarizations. ref http www.esa.int esaLP ESAQGA2VMOC smos 1.html subhead2 SMOS mission Payload . Living Planet Programme . European Space Agency ESA ref The aperture on the LICEF detectors, planar in arrangement on MIRAS, point directly toward the Earth s surface as the satellite orbits. The arrangement and orientation of MIRAS makes the instrument a 2 D interferometric radiometer . The MIRAS instrument s prime contractor was EADS CASA Espacio, manufacturing the payload of SMOS under ESA s contract. LICEF The LICEF detector is composed of a round patch antenna element, with 2 pairs of probes for orthogonal linear polarisations, feeding two receiver channels in a compact lightweight package behind the antenna. ref name SMOSop http www.cp34 smos.icm.csic.es smos mission operating principles.htm Operating Principles SMOS Mission, ICM CSIC Spanish Institute of Marine Sciences Spanish National Research Council , updated July 2008 ref It picks up thermal radiation emitted by the Earth near 1.4 GHz in the microwave L band , amplifies it 100 decibel dB , and digitises it with 1 bit quantisation signal processing quantisation . MIER is the subcontractor. ref http www.esa.int esaLP SEM63AOFGLE index 0.html Last batch of LICEF receivers delivered for SMOS . Living Planet Programme . European Space Agency ESA ref References reflist Satellite and spacecraft instruments Category Embedded systems Category Spacecraft instruments ... more details
other uses Image Aperures.jpg thumb A large 1 and a small 2 aperture Image Aperture in Canon 50mm f1.8 II lens.jpg thumb right Aperture mechanism of Canon 50mm f 1.8 II lens Image ApertureDefn1707.png right thumb 244px Definitions of Aperture in the 1707 Glossographia Anglicana Nova ref Thomas Blount .... Gregory, Mr. Lock, Mr. Evelyn, Mr. Dryden, Mr. Blunt, &c. , London, 1707. ref In optics , an aperture is a hole or an opening through which light travels. More specifically, the aperture of an optical ... optics focus in the image plane . The aperture determines how collimated the admitted rays are, which is of great importance for the appearance at the image plane. If an aperture is narrow, then highly collimated rays are admitted, resulting in a sharp focus at the image plane. If an aperture ... focal length. This means that a wide aperture results in an image that is sharp around what the lens is focusing on and blurred otherwise. The aperture also determines how many of the incoming rays are actually admitted and thus how much light reaches the image plane the narrower the aperture, the darker ... , and the aperture stop is the stop that determines the ray cone angle, or equivalently the brightness, at an image point. In some contexts, especially in photography and astronomy , aperture refers to the diameter of the aperture stop rather than the physical stop or the opening itself. For example, in a telescope the aperture stop is typically the edges of the objective lens or mirror or of the mount that holds it . One then speaks of a telescope as having, for example, a 100 centimeter aperture . Note that the aperture stop is not necessarily the smallest stop in the system. Magnification and demagnification by lenses and other elements can cause a relatively large stop to be the aperture stop for the system. Sometimes stops and diaphragms are called apertures, even when they are not the aperture stop of the system. The word aperture is also used in other contexts to indicate a system ... more details
selfref For the synthesis policy in Wikipedia, see Wikipedia Synthesis wiktionary synthesissynthesis synthesised synthesize synthesized tocright In general, the noun synthesis from the ancient Greek lang ... verb, to synthesize or synthesise , means to make or form a synthesis . Synthesis or synthesize may also refer to Science Chemistry and biochemistry Chemical synthesis , the execution of chemical reactions to form a more complex molecule from chemical precursors Organic synthesis , the chemical synthesis of organic compounds Total synthesis , the complete organic synthesis of complex organic compounds, usually without the aid of biological processes Convergent synthesis or linear synthesis, a strategy to improve the efficiency of multi step chemical syntheses Dehydration reaction Dehydration synthesis , a chemical synthesis resulting in the loss of a water molecule Paal Knorr synthesis , a chemical reaction named after Carl Paal and Ludwig Knorr Biosynthesis , the creation ... , the synthesis of biological compounds into organic waste, using methane or an oxidized molecule as a catalyst Amino acid synthesis , the synthesis of an amino acid from its constituents Peptide synthesis , the biochemical synthesis of peptides using amino acids Protein biosynthesis , the multi step biochemical synthesis of proteins long peptides DNA synthesis disambiguation , several biochemical processes for making DNA DNA replication , DNA biosynthesis in vivo Synthesis cell cycle Transcription genetics RNA synthesis , the synthesis of RNA from nucleic acids, using another nucleic acid chain as a template ATP synthase ATP synthesis , the biochemical synthesis of ATP Physics Nucleosynthesis ... synthesis , the process of converting a higher level form of a design into a lower level implementation High level synthesis , an automated design process that interprets an algorithmic description ... Sound synthesis , various methods of sound generation in audio electronics wave field synthesis , a spatial ... more details
wiktionarypar aperture The aperture of an optical system is the opening that limits the amount of light that can pass through. Aperture may also refer to TOC right Do not add Aperture Science in this article. It is not ambiguous with aperture . Per WP MOSDAB , it does not belong on this disambiguation page see talk page for details. Science and technology Aperture antenna , a physical parameter of an antenna Aperture mollusc , the main opening in the shell of a gastropod or scaphopod mollusc Aperture botany , a weaker spot in the wall of a pollen grain Numerical aperture is a parameter used to describe optical systems Computers Aperture computer memory , a region of the physical address space that opens access to a particular device or memory unit Aperture software , an image organization and editing program for photographers, sold by Apple Inc. Other Aperture typography , an enclosed loop in a typographical symbol such as the lower part of the letter a Aperture magazine Aperture magazine , a long running art photography magazine See also Lookfrom Aperture Includes links to Aperture Science and Aperture Laboratories Intitle Aperture disambig bg cs Clona rozcestn k de Apertur Begriffskl rung es Apertura desambiguaci n nl Apertura ru uk ... more details
Image Angular aperture.svg right The angular aperture of a thin lens with focal point at F and an aperture of diameter math d math . thumb 250px The angular aperture of a lens optics lens is the apparent angle of the lens aperture as seen from the Focus optics focal point math a 2 arctan left frac D 2 f right math where math f math is the focal length math D math is the diameter of the aperture . Relation to numerical aperture In a medium with an index of refraction close to 1, such as air, the angular aperture is approximately equal to twice the numerical aperture of the lens. ref cite book title Studies in Optics author Albert Abraham Michelson year 1995 publisher Courier Dover pages 32 isbn 0 486 68700 7 url http books.google.com books?id m2tUZ4 8WGMC&pg PA32&dq 22Angular aperture 22&ie ISO 8859 1&output html ref Formally, the numerical aperture in air is math mathrm NA sin a 2 sin arctan left frac D 2 f right math In the paraxial approximation , with a small aperture, math D f math math mathrm NA approx a 2 math References reflist See also f number Numerical aperture Category Optics Category Angle de ffnungswinkel es Apertura angular it Apertura angolare nl Openingshoek zh ... more details
advert date April 2011 Refimprove date January 2010 Image vt 1.jpg thumb Aperture Gallery in Chelsea, 547 W 27th Street The Aperture Foundation was founded in 1952 by Ansel Adams , Minor White , Barbara Morgan photographer Barbara Morgan , Dorothea Lange , Nancy Newhall , Beaumont Newhall , Ernest Louie, Melton Ferris, and Dody Warren. Their vision was to create a forum for fine art photography, a new concept at the time. The first issue of Aperture magazine was published in spring 1952 in San Francisco. Aperture s efforts increased respect for photography and its popularity among contemporary ... 2010 10 23 chris boot executive director at aperture ref Aperture is a not for profit. The foundation ... have always defined Aperture Foundation, as expressed by the mission statement blockquote The purpose of Aperture Foundation, a non profit organization, is to advance photography in all its forms and to foster the exchange of ideas among audiences worldwide. blockquote Books Aperture is known as publisher ... diane arbus an aperture monograph.html ref Several of Aperture s approximately 20 new titles a year ... two or three new books are the first ever for the artist in question. Aperture also supports .... Exhibitions In 2005, Aperture s three thousand square foot gallery opened in New York s Chelsea art district. ref name aperture http www.aperture.org about ref Many of the shows travel, to a total of more than 25 venues in the U.S. and abroad each year. Aperture s Chelsea gallery regularly ... City. Selection Aperture has exhibited an eclectic and critically acclaimed array of shows, including ... by Josef Koudelka. ref name aperture File Aperture Gallery2.jpg thumb Aperture Gallery in Chelsea, 547 W 27th Street References references External links http www.aperture.org Aperture Foundation Website http thephotobook.wordpress.com 2010 10 23 chris boot executive director at aperture Chris Boot Director Announcement http www.aperture.org diane arbus an aperture monograph.html Diane Arbus Monograph ... more details
Orphan date September 2008 Dynamic aperture is a term in acoustics used very much like aperture in photography. The arrays in side scan sonar can be programmed to transmit just a few elements at a time or all the elements at once. The more elements transmitting, the narrower the beam and the better the Audio bit depth resolution . The ratio of the aperture size to the imaging depth is known as the F number. Dynamic aperture is keeping this number constant by growing the aperture with the imaging depth until the physical aperture cannot be increased. A modern medical ultrasound machine has a typical F number of 0.5. Side Scan Sonar systems produce images by forming angular beams . Beam width is determined by length of the sonar array, narrower beams resolve finer detail. Longer arrays with narrower beams provide finer spatial resolution. Missing image removed Image beam.jpg Category Acoustics physics stub ... more details
Nasal aperture may refer to Posterior nasal apertures Anterior nasal aperture disambig Short pages monitor This long comment was added to the page to prevent it from being listed on Special Shortpages. It and the accompanying monitoring template were generated via Template Long comment. Please do not remove the monitor template without removing the comment as well. ... more details
, which has a large aperture and a pronounced parietal callus . The aperture is an opening in certain ... emerges for locomotion, feeding, etc. The term aperture is used for the main opening in gastropod ... a main anterior aperture and a smaller posterior aperture. As well as the aperture, some gastropod shells ... called orifices. In gastropods In some prosobranch gastropods, the aperture of the shell can be closed, and even completely sealed, with a sort of door or operculum gastropod operculum . The aperture ... roughly to the cross section of the body whorl of the shell. The aperture of a snail shell can have many other forms semicircular, trilobate or auriculate . In some gastropods, the aperture is narrowed ... layers to the aperture margin also called peristome from the mantle border, the principal agent in the secretion of the shell. Terminology The margin of the aperture is sometimes continuous or entire ... side of the aperture being formed only by the body whorl. For convenience of reference, the margin of a gastropod aperture is divided into three areas The parietal wall with the outer lip labrum the area ... at its base. The palatal wall the outer free wall of the final whorl of the shell. The aperture ... . Shape The shape of the aperture can be auriform, ear shaped, as in Auriculella bean for example ... Aperture shape&state Bean Aperture shape Bean . accessed 3 January 2011. ref circular, rotundate, orbicular. claw shaped aperture Some Melongenidae have a claw shaped aperture. crescent examples ... Molluscs&character Aperture shape&state Crescent Aperture shape Crescent . accessed 3 January 2011. ref distorted aperture Personidae has a distorted aperture. linear, narrow. Cypraea , Conus ... Aperture shape&state Half moon Aperture shape Half moon . accessed 3 January 2011. ref . Nerita ... ref http www.discoverlife.org mp 20q?act x show state&guide Molluscs&character Aperture shape&state Oval or teardrop Aperture shape Oval or teardrop . accessed 3 January 2011. ref ovate, egg shaped ... more details
maximum aperture in hopes of getting enough light for a good exposure. In addition, aperture priority ... its aperture range for a given focal length of the lens. Commonly, lenses provide greatest Angular ... DEFAULTSORT Aperture Priority Category Photography equipment Photo stub be x old de Zeitautomatik ru fi Aukkoautomatiikka sv Slutartidsautomatik th Aperture ... more details
italic title Aperture is a quarterly photography magazine and a book publisher based in Chelsea, Manhattan New York , New York . The magazine is published by Aperture Foundation , a non profit organization devoted to fine art photography . Magazine Inspired by the production quality of Alfred Stieglitz s then defunct Camera Work , Aperture magazine was founded by Minor White , Ansel Adams , Dorothea Lange , Barbara Morgan photographer Barbara Morgan , Nancy Newhall and Beaumont Newhall . ref name ap http www.aperture.org Aperture.org official site ref White, himself a photographer, edited the magazine from its first issue in 1952 until 1975. ref name glbtq cite web url http www.glbtq.com arts white m.html title Minor White 1908 1976 last Lockard first Ray Anne work glbtq.com date 2002 accessdate 2010 04 21 ref He died in 1976. The first iteration of the magazine closed in 1964. Hoffman, a close friend and former student of then editor White, later restored the magazine, becoming its publisher ... houses in the United States and Europe. Aperture agreed to publish Arbus catalog and it was released in time for the show as Diane Arbus An Aperture Monograph . Book publisher Aperture s book publication program began in 1965, with Edward Weston The Flame of Recognition , which became one of Aperture s best selling titles. ref name ap In 1984, Aperture also published The Golden Age of British Photography, 1839 1900 , which featured restored, British Victorian era Victorian Era photography. Aperture Foundation As of 2009, Both Aperture magazine and its book publishing arm are run by the nonprofit arts institution the Aperture Foundation. In 2003, the Foundation instituted the first Aperture Michael E. Hoffman Award, in memory of Michael E. Hoffman died 2001 , who was Aperture s publisher for 37 years. The Aperture Foundation sponsors limited edition portfolios, lectures, conferences and touring ... in 1952 Category Magazines published in New York es Aperture revista ... more details
other uses Aperture disambiguation Infobox Software developer Apple Inc. logo Image Aperture Icon.png 64px 64px Apple Aperture screenshot Image Apple Aperture.jpg 270px Aperture caption Aperture 3, demonstrating ... Proprietary website URL http www.apple.com apertureAperture is a photo editing software photo editing ... article 48600 2005 12 aperture.html title Macworld Aperture 1.0.1 Review publisher Macworld.com ... Store . ref cite web url http itunes.apple.com nl app aperture id408981426?mt 12 title Aperture in the Mac ... corrective adjustments, displaying slideshow s, and printing photographs. Features of Aperture include ... popular websites, including Flickr , Facebook , SmugMug , and Apple s MobileMe service. Aperture 3 ... App Store. ref cite web url http itunes.apple.com us app aperture id408981426?mt 12 title Aperture ... http support.apple.com kb HT4176 title Aperture 3 Tips on tethered shooting publisher apple.com date ... into the Aperture library. Raw Fine Tuning, allowing versions of raw decode to be managed over .... Aperture 2.0 Aperture 2.0 was released on February 12, 2008 with a reduced US price of 199. ref ... Macworld Aperture 2 Review publisher Macworld.com date 2008 03 12 accessdate 2011 02 15 ref This can ... iLife and iWork. Support for editing plug ins, including Apple s own dodging and burning tool Aperture 2.1 . ref cite web url http www.apple.com aperture resources plugins.html title Aperture Resources Plug ins publisher Apple.com date accessdate 2011 02 15 ref Aperture 3.0 Aperture 3.0 was released ... news releases apple releases aperture 3 83877837.html title Apple Press Statement location California publisher Prnewswire.com date accessdate 2011 02 15 ref and is the first version of Aperture ... as follows ref cite web url http www.apple.com aperture features title Apple s feature list publisher ... for download. ref cite web url http aperturepresets.tumblr.com title Custom Aperture presets for download ... created using an external editor. 1.5.3 April 19, 2007 Aperture 1.5.3 addresses issues related ... more details
File CRT Phosphors.jpg 180px thumb Aperture grille based CRT in close up File Trinitron computer.JPG thumb right 180px Sony Trinitron aperture grille computer monitor Image Aperture grille closeup teletext.jpg 180px thumb Aperture grille based CRT in close up, showing the letter e from a teletext page An aperture grille tension mask is one of two major technologies used to manufacture color cathode ray tube CRT television s and computer display s the other is shadow mask . Fine vertical wires behind the front glass of the display screen separate the different colors of phosphor s into strips. These wires are positioned such that an electron beam from one of three guns at the rear of the tube is only able to strike phosphors of the appropriate color. That is, the blue electron gun will strike blue phosphors, but will find a wire blocks the path to red and green phosphors. The fine wires allow for a finer dot pitch as they can be spaced much closer together than the perforations of a shadow mask, and there need be no gap between adjacent horizontal pixels. During the display of bright images, a shadow mask warms, and expand outward in all directions sometimes called blooming . Aperture .... The vertical wires of the aperture grille have a resonant frequency and will vibrate in Acoustic ... aperture grille and shadow mask displays at a glance. The stabilized grille can still vibrate but the sounds need to be loud and close to the display. Additionally, aperture grille displays tend to be vertically ... have a spherical curvature . The first patent ed aperture grille televisions were manufactured by Sony .... Cromaclear is an improvement of the aperture grille technology, pioneered by the NEC Corporation one of its advantage is the lack of the damping wires. While many considered aperture grille technology ... links http www.monitorworld.com faq pages q28 page.html Aperture grille details Category Cathode ray tube de Streifenmaske es Rejilla de apertura it Aperture grille ja ru ... more details
Infobox Brain Name Lateral aperture Latin apertura lateralis ventriculi quarti GraySubject 187 GrayPage 798 Image Lateral ventricle.gif Caption Three dimensional space Three dimensional representation of the ventricular system of the human brain. The fourth ventricle is the lower blue mass. The little points sticking out on the left and right are the two parts of the lateral recess, which end in the foramen of Luschka. Image2 Human caudal brainstem posterior view description.JPG Caption2 Human caudal brainstem posterior view Lateral aperture is 18 IsPartOf Components Artery Vein Acronym LA4V BrainInfoType hier BrainInfoNumber 637 MeshName MeshNumber DorlandsPre a 51 DorlandsSuf 12144677 The lateral aperture is a paired structure in human anatomy. It is an opening in each lateral extremity of the lateral recess of the fourth ventricle of the human brain , which also has a single median aperture . The two lateral apertures provide a conduit for cerebrospinal fluid to flow from the brain s ventricular system into the subarachnoid space specifically into the cerebellopontine angle . The structure is also called the lateral aperture of the fourth ventricle or the foramen of Luschka after anatomist Hubert von Luschka . ref http www.whonamedit.com synd.cfm 2391.html Hubert Von Luschka at whonamedit.com ref References reflist Gray s Fourth ventricle Category Nervous system neuroscience stub nl Apertura lateralis ventriculi quarti ro Orificiu Luschka ... more details
Infobox Brain Name PAGENAME Latin apertura mediana ventriculi quarti GraySubject 187 GrayPage 798 Image Gray708.svg Caption Scheme of roof of fourth ventricle . The arrow is in the foramen of Magendie . Image2 Caption2 IsPartOf Components Artery Vein BrainInfoType hier BrainInfoNumber 638 MeshName MeshNumber DorlandsPre a 51 DorlandsSuf 12144687 The median aperture medial aperture, Foramen of Magendie drains CSF from the fourth ventricle into the cisterna magna . The two lateral aperture s foramina of Luschka , one on the left and one on the right, are the primary routes for drainage of cerebrospinal fluid from the fourth ventricle into the cerebellopontine angle cistern . The foramen on axial images is posterior to the pons and anterior to the Caudal anatomical term caudal cerebellum . Eponym The Foramen of Magendie is named for Fran ois Magendie , who first described it. ref WhoNamedIt synd 2388 ref Addtional images gallery File Slide3qq.JPG Median aperture gallery References reflist Netter, Frank H. 1989 Atlas of Human Anatomy . Summit, NJ Ciba Geigy Corporation. Williams, Peter L. Warwick, Roger Dyson, Mary & Bannister, Lawrence H. 1989 Gray s Anatomy 37th ed. . New York Churchill Livingstone. External links RocheLexicon 13048.000 3 Fourth ventricle Category Central nervous system neuroscience stub it Foro di Magendie nl Apertura mediana ventriculi quarti pt Abertura mediana ro Orificiul Magendie vi L gi a ... more details
Image Aperture card.JPG 400px right An aperture card is a type of punched card with a cut out window into which a chip of microform microfilm is mounted. Such a card is used for archive archiving or for making multiple inexpensive copies of a document for ease of distribution. The card is typically punched with machine readable metadata associated with the microfilm image, and printed across the top of the card for visual identification. The microfilm chip is most commonly 35mm in height, and contains an optics optically reduced image, usually of some type of reference document, such as an engineering drawing , that is the focus of the archiving process. Aperture cards have several advantages and disadvantages when compared to digital systems. Machinery exists to automatically store, retrieve, sort, duplicate, create, and digitize cards with a high level of automation. While many aperture ... systems. Usage Aperture cards are used for engineering drawings from all engineering disciplines. The U.S. Department of Defense once made extensive use of aperture cards, and some are still in use, but most ... use of aperture cards ref Information about the drawing, for example the drawing number, could be both ... and a light source. Advantages Aperture cards have, for archival purposes, some advantages over digital ... paper first Ed last LoTurco title The Engineering Aperture Card Still Active, Still Vital publisher ... and purposes lost forever unless it s later found by accident. Aperture cards created from 35mm ... that Image scanner scan aperture cards and produce a digital version. ref For example, this aperture ...&PRODUCT 3C 3Eprd id 845524441761057 Oce ref Aperture card plotters are machines that use a laser to create the image on the film. ref For example, this aperture card plotter from http www.wwl.co.uk ... www scit en standards pdf 03 07 a.pdf Detailed description of a particular format of Aperture cards ... microforms and aperture cards References Reflist Category Archival science Category History of computing ... more details
Context date February 2008 Refimprove date July 2007 File Coded aperture mask for gamma camera .jpg thumb Coded aperture mask for gamma camera for SPECT Coded Apertures or Coded Aperture Masks are grids, gratings, or other patterns of materials opaque to various wavelengths of light. The wavelengths are usually high energy radiation such as X rays and gamma rays . By blocking and unblocking light in a known pattern, a coded shadow is cast upon a plane of detectors. Using computer algorithms, properties of the original light source can be deduced from the shadow on the detectors. Coded apertures are used in X and gamma rays because their high energies pass through normal lenses and mirrors. Rationale Image formation, normally done at optical wavelengths by lenses and mirrors, must be done for non focusable wavelengths via image modulation. The pinhole camera is the most basic form of such a modulation imager, but a single aperture mask can contain many holes, in one of several particular patterns, to improve the throughput for hard X ray s and Gamma ray &gamma rays , for example. Multiple masks, at varying distances from a detector, add flexibility to this tool. Specifically the modulation collimator , invented by Minoru Oda , was used to identify the first cosmic X ray source and thereby to launch the new field of X ray astronomy in 1965. Many other applications in other fields, such as tomography , have since appeared. In a coded aperture more complicated than a pinhole camera , images from multiple apertures will overlap at the plate or detector array. It is thus necessary to use a computational algorithm which depends on the precise configuration of the aperture arrays ... can be applied. The coded aperture imaging technique is one of the earliest forms of computational .... URA MURA Levin Veeraraghavan Coded Aperture Space Telescopes Rossi X ray Timing Explorer ASM BeppoSAX ... ray computed tomography External links Coded Aperture Imaging in High Energy Astronomy http astrophysics.gsfc.nasa.gov ... more details
Refimprove date December 2009 In electromagnetics and antenna radio antenna theory, antenna aperture or effective area is a measure of how effective an antenna is at receiving the power of radio wave s. The aperture ... density PFD watts per square metre, the antenna s aperture A sub eff sub in square metres is given ... is equal to the power density of the radio waves in watts per square metre, multiplied by its aperture in square metres. The larger an antenna s aperture is, the more power it can collect from a given ... advantage of its maximum gain. Aperture efficiency In general, the aperture of an antenna is not directly ... antenna horns , have a physical aperture opening which collects the radio waves. In these aperture antennas , the effective aperture A sub eff sub must always be less than the area of the antenna s physical aperture A sub phys sub , as can be seen from the definition above. An antenna s aperture ... The aperture efficiency is a dimensionless parameter between 0 and 1.0 that measures how far the antenna falls short of using all the radio power entering its physical aperture. If the antenna were perfectly efficient, all the radio power falling within its physical aperture would be converted to electrical ... A sub eff sub A sub phys sub and the aperture efficiency would be 1.0. But all antennas have ... by its Antenna feed feed , and radio waves scattered by structural supports and diffraction at the aperture edge, which reduce the power output. Aperture efficiencies of typical antennas vary from 0.35 to 0.70 but can range up to 0.90. Aperture and gain The directivity of an antenna, its ability to direct ... equally well from all directions. It can be shown that the aperture of a lossless isotropic antenna ... of the radio waves. So the gain of any antenna is proportional to its aperture math G frac 4 pi ..., the gain and aperture are understood to refer to the antenna s axis of maximum gain, or boresight ... in watts A sub r sub is the aperture of the receiving antenna in m sup 2 sup A sub t sub is the aperture ... more details
Image Numerical aperture.svg right thumb The numerical aperture with respect to a point P depends on the half ... aperture NA of an optical system is a dimensionless number that characterizes the range of angles ... between different areas of optics. Numerical aperture is commonly used in microscopy to describe the acceptance ... In most areas of optics, and especially in microscopy , the numerical aperture of an optical system ... across an interface. In air, the angular aperture of the lens is approximately twice this value within ... 2NA, where is the wavelength of the light. A lens with a larger numerical aperture will be able to visualize finer details than a lens with a smaller numerical aperture. Assuming quality diffraction ... a brighter image, but will provide shallower depth of field . Numerical aperture is used to define ... DVD and Blu ray by Steve Kindig, Crutchfield Advisor . Accessed 2008 01 18. ref Numerical aperture versus f number Image Numerical aperture for a lens.svg thumb 250px right Numerical aperture of a thin lens . Numerical aperture is not typically used in photography . Instead, the angular aperture ... N f D math This ratio is related to the image space numerical aperture when the lens is focused at infinity. ref name Greivenkamp Based on the diagram at the right, the image space numerical aperture ... holds when the numerical aperture is small, but it turns out that for well corrected optical systems ... aperture may be more meaningful. Working or effective f number The f number describes the light ... the light gathering ability of the lens or the image side numerical aperture. In this case, the numerical aperture is related to what is sometimes called the working f number or effective f number ...&pg PA29&dq inauthor greivenkamp numerical aperture p. 29. ref ref cite book title Field Guide ... aperture ref The magnification here is typically negative in photography, the factor is sometimes ..., the object side numerical aperture is related to the f number by way of the magnification tending ... more details
About pollen structure stomatal aperture Stoma Apertures are very small spots on the walls of a pollen , where the wall is thinner and or softer. For germination it is necessary that the pollen tube can reach out from the inner of the pollen and transport the chromosome s to the egg deep down in the Carpel pistil . The apertures are the places where the pollen tube is able to break through the elsewhere very tough pollen wall. The number and configuration of apertures are often very exactly defined for and characteristic for different groups of plants. The biggest class of plant species, Eudicots Eudicotyledonae has three apertures in each pollen. References citation pmid 9735262 year 1998 month Jul author Ressayre, A Godelle, B Mignot, A Gouyon, Ph title A Morphogenetic Model Accounting for Pollen Aperture Pattern in Flowering Plants volume 193 issue 2 pages 321 334 doi 10.1006 jtbi.1998.0704 journal Journal of theoretical biology Further reading citation doi 10.1016 j.revpalbo.2006.06.008 url http www.bio.uu.nl palaeo glossary glos int.htm title Glossary of pollen and spore terminology year 2007 author Punt, W journal Review of Palaeobotany and Palynology volume 143 issue 1 2 pages 1 last2 Hoen first2 P last3 Blackmore first3 S last4 Nilsson first4 S last5 Lethomas first5 A Category Pollination botany stub ... more details
Notability date October 2008 Unreferenced date May 2008 Synthetic aperture magnetometry SAM is a method for analysis of data obtained from magnetoencephalography MEG and electroencephalography EEG . SAM is a nonlinear beamforming approach which can be thought of as a spatial filter . Fact date October 2008 See also Aperturesynthesis Category Magnetoencephalography ... more details
Purine synthesis may either refer to In vivo purine synthesis Purine metabolism Synthesis Laboratory purine synthesis Purine Synthesis disambig ... more details
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