The Experts below are selected from a list of 6069 Experts worldwide ranked by ideXlab platform
P M Kilmartin - One of the best experts on this subject based on the ideXlab platform.
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MOA-cam3: a wide-field mosaic CCD camera for a gravitational microlensing survey in New Zealand
Experimental Astronomy, 2008Co-Authors: T Sako, T Sekiguchi, M Sasaki, K Okajima, F Abe, I A Bond, J B Hearnshaw, Y Itow, K Kamiya, P M KilmartinAbstract:We have developed a wide-field mosaic CCD camera, MOA-cam3, mounted at the prime focus of the Microlensing Observations in Astrophysics (MOA) 1.8-m telescope. The camera consists of ten E2V CCD4482 chips, each having 2k×4k pixels, and covers a 2.2 deg^2 field of view with a single exposure. The optical system is well optimized to realize uniform image quality over this wide field. The chips are constantly cooled by a cryocooler at − 80° C, at which temperature Dark Current Noise is negligible for a typical 1–3 min exposure. The CCD output charge is converted to a 16-bit digital signal by the GenIII system (Astronomical Research Cameras Inc.) and readout is within 25 s. Readout Noise of 2–3 ADU (rms) is also negligible. We prepared a wide-band red filter for an effective microlensing survey and also Bessell V, I filters for standard astronomical studies. Microlensing studies have entered into a new era, which requires more statistics, and more rapid alerts to catch exotic light curves. Our new system is a powerful tool to realize both these requirements.
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moa cam3 a wide field mosaic ccd camera for a gravitational microlensing survey in new zealand
arXiv: Astrophysics, 2008Co-Authors: T Sako, T Sekiguchi, M Sasaki, K Okajima, F Abe, I A Bond, J B Hearnshaw, Y Itow, K Kamiya, P M KilmartinAbstract:We have developed a wide-field mosaic CCD camera, MOA-cam3, mounted at the prime focus of the Microlensing Observations in Astrophysics (MOA) 1.8-m telescope. The camera consists of ten E2V CCD4482 chips, each having 2kx4k pixels, and covers a 2.2 deg^2 field of view with a single exposure. The optical system is well optimized to realize uniform image quality over this wide field. The chips are constantly cooled by a cryocooler at -80C, at which temperature Dark Current Noise is negligible for a typical 1-3 minute exposure. The CCD output charge is converted to a 16-bit digital signal by the GenIII system (Astronomical Research Cameras Inc.) and readout is within 25 seconds. Readout Noise of 2--3 ADU (rms) is also negligible. We prepared a wide-band red filter for an effective microlensing survey and also Bessell V, I filters for standard astronomical studies. Microlensing studies have entered into a new era, which requires more statistics, and more rapid alerts to catch exotic light curves. Our new system is a powerful tool to realize both these requirements.
T Sako - One of the best experts on this subject based on the ideXlab platform.
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MOA-cam3: a wide-field mosaic CCD camera for a gravitational microlensing survey in New Zealand
Experimental Astronomy, 2008Co-Authors: T Sako, T Sekiguchi, M Sasaki, K Okajima, F Abe, I A Bond, J B Hearnshaw, Y Itow, K Kamiya, P M KilmartinAbstract:We have developed a wide-field mosaic CCD camera, MOA-cam3, mounted at the prime focus of the Microlensing Observations in Astrophysics (MOA) 1.8-m telescope. The camera consists of ten E2V CCD4482 chips, each having 2k×4k pixels, and covers a 2.2 deg^2 field of view with a single exposure. The optical system is well optimized to realize uniform image quality over this wide field. The chips are constantly cooled by a cryocooler at − 80° C, at which temperature Dark Current Noise is negligible for a typical 1–3 min exposure. The CCD output charge is converted to a 16-bit digital signal by the GenIII system (Astronomical Research Cameras Inc.) and readout is within 25 s. Readout Noise of 2–3 ADU (rms) is also negligible. We prepared a wide-band red filter for an effective microlensing survey and also Bessell V, I filters for standard astronomical studies. Microlensing studies have entered into a new era, which requires more statistics, and more rapid alerts to catch exotic light curves. Our new system is a powerful tool to realize both these requirements.
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moa cam3 a wide field mosaic ccd camera for a gravitational microlensing survey in new zealand
arXiv: Astrophysics, 2008Co-Authors: T Sako, T Sekiguchi, M Sasaki, K Okajima, F Abe, I A Bond, J B Hearnshaw, Y Itow, K Kamiya, P M KilmartinAbstract:We have developed a wide-field mosaic CCD camera, MOA-cam3, mounted at the prime focus of the Microlensing Observations in Astrophysics (MOA) 1.8-m telescope. The camera consists of ten E2V CCD4482 chips, each having 2kx4k pixels, and covers a 2.2 deg^2 field of view with a single exposure. The optical system is well optimized to realize uniform image quality over this wide field. The chips are constantly cooled by a cryocooler at -80C, at which temperature Dark Current Noise is negligible for a typical 1-3 minute exposure. The CCD output charge is converted to a 16-bit digital signal by the GenIII system (Astronomical Research Cameras Inc.) and readout is within 25 seconds. Readout Noise of 2--3 ADU (rms) is also negligible. We prepared a wide-band red filter for an effective microlensing survey and also Bessell V, I filters for standard astronomical studies. Microlensing studies have entered into a new era, which requires more statistics, and more rapid alerts to catch exotic light curves. Our new system is a powerful tool to realize both these requirements.
Alexander M Dizhoor - One of the best experts on this subject based on the ideXlab platform.
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gucy2d cone rod dystrophy 6 is a phototransduction disease triggered by abnormal calcium feedback on retinal membrane guanylyl cyclase 1
The Journal of Neuroscience, 2018Co-Authors: Shinya Sato, Elena V Olshevskaya, Igor V Peshenko, Vladimir J Kefalov, Alexander M DizhoorAbstract:The Arg838Ser mutation in retinal membrane guanylyl cyclase 1 (RetGC1) has been linked to autosomal dominant cone-rod dystrophy type 6 (CORD6). It is believed that photoreceptor degeneration is caused by the altered sensitivity of RetGC1 to calcium regulation via guanylyl cyclase activating proteins (GCAP). To determine the mechanism by which this mutation leads to degeneration, we investigated the structure and function of rod photoreceptors in two transgenic mouse lines, 362 and 379, expressing R838S RetGC1. In both lines, rod outer segments became shorter than in their non-transgenic siblings by 3-4 weeks of age, before the eventual photoreceptor degeneration. Despite the shortening of their outer segments, the Dark Current of transgenic rods was 1.5—2.2-fold higher than in non-transgenic controls. Similarly, the dim flash response amplitude in R838S + rods was larger, time to peak was delayed, and flash sensitivity was increased, all suggesting elevated Dark-adapted free cGMP in transgenic rods. In rods expressing R838S RetGC1, Dark Current Noise increased and the exchange Current, detected after a saturating flash, became more pronounced. These results suggest disrupted Ca 2+ phototransduction feedback and abnormally high free Ca 2+ concentration in the outer segments. Notably, photoreceptor degeneration, which typically occurred after 3 months of age in R838S RetGC1 transgenic mice in GCAP1,2 +/+ or GCAP1,2 +/- backgrounds, was completely prevented in GCAP1,2 -/- mice lacking Ca 2+ feedback to guanylyl cyclase. In summary, the dysregulation of guanylyl cyclase in RetGC1-linked CORD6 is a ‘phototransduction disease9, associated with increase in free cGMP and Ca 2+ levels in photoreceptors. SIGNIFICANCE STATEMENT In a mouse model expressing human membrane guanylyl cyclase 1 (RetGC1, GUCY2D ), a mutation associated with early progressing congenital blindness, cone-rod dystrophy type 6 (CORD6), deregulates calcium-sensitive feedback of phototransduction to the cyclase mediated by calcium-sensor proteins GCAPs. The abnormal calcium sensitivity of the cyclase increases cGMP-gated Dark Current in the rod outer segments, re-shapes rod photoresponses, and triggers photoreceptor death. This work is the first to demonstrate a direct physiological effect of GUCY2D CORD6-linked mutation on photoreceptor physiology in vivo . It also identifies the abnormal regulation of the cyclase by calcium-sensor proteins as the main trigger for the photoreceptor death.
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gucy2d cone rod dystrophy 6 is a phototransduction disease triggered by abnormal calcium feedback on retinal membrane guanylyl cyclase 1
The Journal of Neuroscience, 2018Co-Authors: Shinya Sato, Elena V Olshevskaya, Igor V Peshenko, Vladimir J Kefalov, Alexander M DizhoorAbstract:The Arg838Ser mutation in retinal membrane guanylyl cyclase 1 (RetGC1) has been linked to autosomal dominant cone-rod dystrophy type 6 (CORD6). It is believed that photoreceptor degeneration is caused by the altered sensitivity of RetGC1 to calcium regulation via guanylyl cyclase activating proteins (GCAPs). To determine the mechanism by which this mutation leads to degeneration, we investigated the structure and function of rod photoreceptors in two transgenic mouse lines, 362 and 379, expressing R838S RetGC1. In both lines, rod outer segments became shorter than in their nontransgenic siblings by 3-4 weeks of age, before the eventual photoreceptor degeneration. Despite the shortening of their outer segments, the Dark Current of transgenic rods was 1.5-2.2-fold higher than in nontransgenic controls. Similarly, the dim flash response amplitude in R838S+ rods was larger, time to peak was delayed, and flash sensitivity was increased, all suggesting elevated Dark-adapted free cGMP in transgenic rods. In rods expressing R838S RetGC1, Dark-Current Noise increased and the exchange Current, detected after a saturating flash, became more pronounced. These results suggest disrupted Ca2+ phototransduction feedback and abnormally high free-Ca2+ concentration in the outer segments. Notably, photoreceptor degeneration, which typically occurred after 3 months of age in R838S RetGC1 transgenic mice in GCAP1,2+/+ or GCAP1,2+/- backgrounds, was prevented in GCAP1,2-/- mice lacking Ca2+ feedback to guanylyl cyclase. In summary, the dysregulation of guanylyl cyclase in RetGC1-linked CORD6 is a "phototransduction disease," which means it is associated with increased free-cGMP and Ca2+ levels in photoreceptors.SIGNIFICANCE STATEMENT In a mouse model expressing human membrane guanylyl cyclase 1 (RetGC1, GUCY2D), a mutation associated with early progressing congenital blindness, cone-rod dystrophy type 6 (CORD6), deregulates calcium-sensitive feedback of phototransduction to the cyclase mediated by guanylyl cyclase activating proteins (GCAPs), which are calcium-sensor proteins. The abnormal calcium sensitivity of the cyclase increases cGMP-gated Dark Current in the rod outer segments, reshapes rod photoresponses, and triggers photoreceptor death. This work is the first to demonstrate a direct physiological effect of GUCY2D CORD6-linked mutation on photoreceptor physiology in vivo It also identifies the abnormal regulation of the cyclase by calcium-sensor proteins as the main trigger for the photoreceptor death.
Y Itow - One of the best experts on this subject based on the ideXlab platform.
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MOA-cam3: a wide-field mosaic CCD camera for a gravitational microlensing survey in New Zealand
Experimental Astronomy, 2008Co-Authors: T Sako, T Sekiguchi, M Sasaki, K Okajima, F Abe, I A Bond, J B Hearnshaw, Y Itow, K Kamiya, P M KilmartinAbstract:We have developed a wide-field mosaic CCD camera, MOA-cam3, mounted at the prime focus of the Microlensing Observations in Astrophysics (MOA) 1.8-m telescope. The camera consists of ten E2V CCD4482 chips, each having 2k×4k pixels, and covers a 2.2 deg^2 field of view with a single exposure. The optical system is well optimized to realize uniform image quality over this wide field. The chips are constantly cooled by a cryocooler at − 80° C, at which temperature Dark Current Noise is negligible for a typical 1–3 min exposure. The CCD output charge is converted to a 16-bit digital signal by the GenIII system (Astronomical Research Cameras Inc.) and readout is within 25 s. Readout Noise of 2–3 ADU (rms) is also negligible. We prepared a wide-band red filter for an effective microlensing survey and also Bessell V, I filters for standard astronomical studies. Microlensing studies have entered into a new era, which requires more statistics, and more rapid alerts to catch exotic light curves. Our new system is a powerful tool to realize both these requirements.
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moa cam3 a wide field mosaic ccd camera for a gravitational microlensing survey in new zealand
arXiv: Astrophysics, 2008Co-Authors: T Sako, T Sekiguchi, M Sasaki, K Okajima, F Abe, I A Bond, J B Hearnshaw, Y Itow, K Kamiya, P M KilmartinAbstract:We have developed a wide-field mosaic CCD camera, MOA-cam3, mounted at the prime focus of the Microlensing Observations in Astrophysics (MOA) 1.8-m telescope. The camera consists of ten E2V CCD4482 chips, each having 2kx4k pixels, and covers a 2.2 deg^2 field of view with a single exposure. The optical system is well optimized to realize uniform image quality over this wide field. The chips are constantly cooled by a cryocooler at -80C, at which temperature Dark Current Noise is negligible for a typical 1-3 minute exposure. The CCD output charge is converted to a 16-bit digital signal by the GenIII system (Astronomical Research Cameras Inc.) and readout is within 25 seconds. Readout Noise of 2--3 ADU (rms) is also negligible. We prepared a wide-band red filter for an effective microlensing survey and also Bessell V, I filters for standard astronomical studies. Microlensing studies have entered into a new era, which requires more statistics, and more rapid alerts to catch exotic light curves. Our new system is a powerful tool to realize both these requirements.
J B Hearnshaw - One of the best experts on this subject based on the ideXlab platform.
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MOA-cam3: a wide-field mosaic CCD camera for a gravitational microlensing survey in New Zealand
Experimental Astronomy, 2008Co-Authors: T Sako, T Sekiguchi, M Sasaki, K Okajima, F Abe, I A Bond, J B Hearnshaw, Y Itow, K Kamiya, P M KilmartinAbstract:We have developed a wide-field mosaic CCD camera, MOA-cam3, mounted at the prime focus of the Microlensing Observations in Astrophysics (MOA) 1.8-m telescope. The camera consists of ten E2V CCD4482 chips, each having 2k×4k pixels, and covers a 2.2 deg^2 field of view with a single exposure. The optical system is well optimized to realize uniform image quality over this wide field. The chips are constantly cooled by a cryocooler at − 80° C, at which temperature Dark Current Noise is negligible for a typical 1–3 min exposure. The CCD output charge is converted to a 16-bit digital signal by the GenIII system (Astronomical Research Cameras Inc.) and readout is within 25 s. Readout Noise of 2–3 ADU (rms) is also negligible. We prepared a wide-band red filter for an effective microlensing survey and also Bessell V, I filters for standard astronomical studies. Microlensing studies have entered into a new era, which requires more statistics, and more rapid alerts to catch exotic light curves. Our new system is a powerful tool to realize both these requirements.
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moa cam3 a wide field mosaic ccd camera for a gravitational microlensing survey in new zealand
arXiv: Astrophysics, 2008Co-Authors: T Sako, T Sekiguchi, M Sasaki, K Okajima, F Abe, I A Bond, J B Hearnshaw, Y Itow, K Kamiya, P M KilmartinAbstract:We have developed a wide-field mosaic CCD camera, MOA-cam3, mounted at the prime focus of the Microlensing Observations in Astrophysics (MOA) 1.8-m telescope. The camera consists of ten E2V CCD4482 chips, each having 2kx4k pixels, and covers a 2.2 deg^2 field of view with a single exposure. The optical system is well optimized to realize uniform image quality over this wide field. The chips are constantly cooled by a cryocooler at -80C, at which temperature Dark Current Noise is negligible for a typical 1-3 minute exposure. The CCD output charge is converted to a 16-bit digital signal by the GenIII system (Astronomical Research Cameras Inc.) and readout is within 25 seconds. Readout Noise of 2--3 ADU (rms) is also negligible. We prepared a wide-band red filter for an effective microlensing survey and also Bessell V, I filters for standard astronomical studies. Microlensing studies have entered into a new era, which requires more statistics, and more rapid alerts to catch exotic light curves. Our new system is a powerful tool to realize both these requirements.
