The Experts below are selected from a list of 240 Experts worldwide ranked by ideXlab platform
Orlando Moreira-filho - One of the best experts on this subject based on the ideXlab platform.
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B chromosomes in Astyanax scabripinnis (Pisces, Characidae)
Heredity, 1992Co-Authors: Lara Bellintani Salvador, Orlando Moreira-filhoAbstract:A karyotypic analysis was carried out using conventional staining and C-banding in 32 specimens of Astyanax scabripinnis (Pisces, Characidae) from Campos do Jordao (Sao Paulo State, Brazil). Twenty-eight individuals (87.5 per cent of the sample studied) showed 1–2 extra B-chromosomes, similar in size and shape (metacentrics) to pair 1 of the karyotype, with a high intra-individual constancy. Two types of B could be identified on the basis of their constitutive heterochromatin patterns. The hypothesis of the origin of the B-chromosome from non-disjunction of chromosome 1, followed by a heterochromatinization process, is postulated.
J. Manousoyanaki - One of the best experts on this subject based on the ideXlab platform.
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Peculiar motions in superclusters : Perseus-Pisces.
Astronomy and Astrophysics, 1993Co-Authors: C. Baffa, G. Chincarini, R. B. C. Henry, J. ManousoyanakiAbstract:We discuss the near infrared observations obtained for a set of 81 galaxies in the region of the Perseus-Pisces supercluster. From these, in conjunction with the 21 cm data of the Arecibo sample, we estimate the peculiar velocities via the Tully-Fisher relation and the model of the local perturbations as derived by Han and Mould. From the data discussed we find that the supercluster main structure is shrinking. To explain the size and velocities observed the model requires, for the supercluster, a mean overdensity of about Δρ/ρ = 9 which corresponds to a total mass of 10 16 solar masses to cover an extension of about 100 Mpc
Branimir Sesar - One of the best experts on this subject based on the ideXlab platform.
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HALO VELOCITY GROUPS IN THE Pisces OVERDENSITY
The Astrophysical Journal, 2010Co-Authors: Branimir Sesar, A. Katherina Vivas, Sonia Duffau, Željko IvezićAbstract:We report spectroscopic observations of five faint (V ~ 20) RR Lyrae stars associated with the Pisces overdensity conducted with the Gemini South Telescope. At a heliocentric and galactocentric distance of ~80 kpc, this is the most distant substructure in the Galactic halo known to date. We combined our observations with literature data and confirmed that the substructure is composed of two different kinematic groups. The main group contains eight stars and has V gsr = 50 km s–1, while the second group contains four stars at a velocity of V gsr = –52 km s–1, where V gsr is the radial velocity in the galactocentric standard of rest. The metallicity distribution of RR Lyrae stars in the Pisces overdensity is centered on [Fe/H] = –1.5 dex and has a width of 0.3 dex. The new data allowed us to establish that both groups are spatially extended making it very unlikely that they are bound systems, and are more likely to be debris of a tidally disrupted galaxy or galaxies. Due to small sky coverage, it is still unclear whether these groups have the same or different progenitors.
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spectroscopic confirmation of the Pisces overdensity
The Astrophysical Journal, 2009Co-Authors: Juna A. Kollmeier, Andrew Gould, Stephen A. Shectman, Ian B. Thompson, George W. Preston, Joshua D. Simon, Jeffrey D. Crane, željko Ivezic, Branimir SesarAbstract:We present spectroscopic confirmation of the 'Pisces Overdensity', also known as 'Structure J', a photometric overdensity of RR Lyrae stars discovered by the Sloan Digital Sky Survey at an estimated photometric distance of approx85 kpc. We measure radial velocities for eight RR Lyrae stars within Pisces. We find that five of the eight stars have heliocentric radial velocities within a narrow range of -87 km s{sup -1} < v{sub r} < -67 km s{sup -1}, suggesting that the photometric overdensity is mainly due to a physically associated system, probably a dwarf galaxy or a disrupted galaxy. Two of the remaining three stars differ from one another by only 9 km s{sup -1}, but it would be premature to identify them as a second system.
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Spectroscopic Confirmation of the Pisces Overdensity
The Astrophysical Journal, 2009Co-Authors: Juna A. Kollmeier, Andrew Gould, Stephen A. Shectman, Ian B. Thompson, George W. Preston, Joshua D. Simon, Jeffrey D. Crane, Željko Ivezić, Branimir SesarAbstract:We present spectroscopic confirmation of the "Pisces Overdensity", also known as "Structure J", a photometric overdensity of RR Lyrae stars discovered by the Sloan Digital Sky Survey (SDSS) at an estimated photometric distance of ~85kpc. We measure radial velocities for 8 RR Lyrae stars within Pisces. We find that 5 of the 8 stars have heliocentric radial velocities within a narrow range of -87 km/s < v < -67 km/s, suggesting that the photometric overdensity is mainly due to a physically associated system, probably a dwarf galaxy or a disrupted galaxy. Two of the remaining 3 stars differ from one another by only 9 km/s, but it would be premature to identify them as a second system.
Michael W. Mcelwain - One of the best experts on this subject based on the ideXlab platform.
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Commissioning and performance results of the WFIRST/Pisces integral field spectrograph
arXiv: Instrumentation and Methods for Astrophysics, 2017Co-Authors: Prabal Saxena, Avi Mandell, Qian Gong, Maxime Rizzo, Camilo Mejia Prada, Jorge Llop Sayson, Eric Cady, Tyler Groff, Michael W. McelwainAbstract:The Prototype Imaging Spectrograph for Coronagraphic Exoplanet Studies (Pisces) is a high contrast integral field spectrograph (IFS) whose design was driven by WFIRST coronagraph instrument requirements. We present commissioning and operational results using Pisces as a camera on the High Contrast Imaging Testbed at JPL. Pisces has demonstrated ability to achieve high contrast spectral retrieval with flight-like data reduction and analysis techniques.
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commissioning and performance results of the wfirst Pisces integral field spectrograph
arXiv: Instrumentation and Methods for Astrophysics, 2017Co-Authors: Prabal Saxena, Avi Mandell, Qian Gong, Maxime Rizzo, Camilo Mejia Prada, Jorge Llop Sayson, Eric Cady, Tyler Groff, Michael W. McelwainAbstract:The Prototype Imaging Spectrograph for Coronagraphic Exoplanet Studies (Pisces) is a high contrast integral field spectrograph (IFS) whose design was driven by WFIRST coronagraph instrument requirements. We present commissioning and operational results using Pisces as a camera on the High Contrast Imaging Testbed at JPL. Pisces has demonstrated ability to achieve high contrast spectral retrieval with flight-like data reduction and analysis techniques.
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Pisces: an integral field spectrograph technology demonstration for the WFIRST coronagraph
Space Telescopes and Instrumentation 2016: Optical Infrared and Millimeter Wave, 2016Co-Authors: Michael W. Mcelwain, Avi Mandell, Qian Gong, Jorge Llop-sayson, Timothy D. Brandt, Victor J. Chambers, Bryan Grammer, Bradford Greeley, George Hilton, Marshall D. PerrinAbstract:We present the design, integration, and test of the Prototype Imaging Spectrograph for Coronagraphic Exoplanet Studies (Pisces) integral field spectrograph (IFS). The Pisces design meets the science requirements for the Wide-Field InfraRed Survey Telescope (WFIRST) Coronagraph Instrument (CGI). Pisces was integrated and tested in the integral field spectroscopy laboratory at NASA Goddard. In June 2016, Pisces was delivered to the Jet Propulsion Laboratory (JPL) where it was integrated with the Shaped Pupil Coronagraph (SPC) High Contrast Imaging Testbed (HCIT). The SPC/Pisces configuration will demonstrate high contrast integral field spectroscopy as part of the WFIRST CGI technology development program.
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Prototype imaging spectrograph for coronagraphic exoplanet studies (Pisces) for WFIRST/AFTA
Techniques and Instrumentation for Detection of Exoplanets VII, 2015Co-Authors: Qian Gong, Michael W. Mcelwain, Bryan Grammer, Bradford Greeley, George Hilton, Jorge Llop Sayson, Catherine T. Marx, Nargess Memarsadeghi, Karl R. Stapelfeldt, Marshall D. PerrinAbstract:Prototype Imaging Spectrograph for Coronagraphic Exoplanet Studies (Pisces) is a lenslet array based integral field spectrometer (IFS) designed for high contrast imaging of extrasolar planets. Pisces will be used to advance the technology readiness of the high contrast IFS baselined on the Wide-Field InfraRed Survey Telescope/Astrophysics Focused Telescope Assets (WFIRST-AFTA) coronagraph instrument. Pisces will be integrated into the high contrast imaging testbed (HCIT) at the Jet Propulsion Laboratory (JPL) and will work with both the Hybrid Lyot Coronagraph (HLC) and the Shaped Pupil Coronagraph (SPC) configurations. We discuss why the lenslet array based IFS was selected for Pisces. We present the Pisces optical design, including the similarities and differences of lenslet based IFSs to normal spectrometers, the trade-off between a refractive design and reflective design, as well as the specific function of our pinhole mask on the back surface of the lenslet array to reduce the diffraction from the edge of the lenslets. The optical analysis, alignment plan, and mechanical design of the instrument will be discussed.
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prototype imaging spectrograph for coronagraphic exoplanet studies Pisces for wfirst afta
Proceedings of SPIE, 2015Co-Authors: Qian Gong, Michael W. Mcelwain, Bryan Grammer, Bradford Greeley, George Hilton, Jorge Llop Sayson, Catherine T. Marx, Nargess Memarsadeghi, Karl R. Stapelfeldt, Marshall D. PerrinAbstract:Prototype Imaging Spectrograph for Coronagraphic Exoplanet Studies (Pisces) is a lenslet array based integral field spectrometer (IFS) designed for high contrast imaging of extrasolar planets. Pisces will be used to advance the technology readiness of the high contrast IFS baselined on the Wide-Field InfraRed Survey Telescope/Astrophysics Focused Telescope Assets (WFIRST-AFTA) coronagraph instrument. Pisces will be integrated into the high contrast imaging testbed (HCIT) at the Jet Propulsion Laboratory (JPL) and will work with both the Hybrid Lyot Coronagraph (HLC) and the Shaped Pupil Coronagraph (SPC) configurations. We discuss why the lenslet array based IFS was selected for Pisces. We present the Pisces optical design, including the similarities and differences of lenslet based IFSs to normal spectrometers, the trade-off between a refractive design and reflective design, as well as the specific function of our pinhole mask on the back surface of the lenslet array to reduce the diffraction from the edge of the lenslets. The optical analysis, alignment plan, and mechanical design of the instrument will be discussed.
Roland L Dunbrack - One of the best experts on this subject based on the ideXlab platform.
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Pisces recent improvements to a pdb sequence culling server
Nucleic Acids Research, 2005Co-Authors: Guoli Wang, Roland L DunbrackAbstract:Pisces is a database server for producing lists of sequences from the Protein Data Bank (PDB) using a number of entry- and chain-specific criteria and mutual sequence identity. Our goal in culling the PDB is to provide the longest list possible of the highest resolution structures that fulfill the sequence identity and structural quality cut-offs. The new Pisces server uses a combination of PSI-BLAST and structure-based alignments to determine sequence identities. Structure alignment produces more complete alignments and therefore more accurate sequence identities than PSI-BLAST. Pisces now allows a user to cull the PDB by-entry in addition to the standard culling by individual chains. In this scenario, a list will contain only entries that do not have a chain that has a sequence identity to any chain in any other entry in the list over the sequence identity cut-off. Pisces also provides fully annotated sequences including gene name and species. The server allows a user to cull an input list of entries or chains, so that other criteria, such as function, can be used. Results from a search on the re-engineered RCSB's site for the PDB can be entered into the Pisces server by a single click, combining the powerful searching abilities of the PDB with Pisces's utilities for sequence culling. The server's data are updated weekly. The server is available at http://dunbrack.fccc.edu/Pisces.
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Pisces a protein sequence culling server
Bioinformatics, 2003Co-Authors: Guoli Wang, Roland L DunbrackAbstract:Pisces is a public server for culling sets of protein sequences from the Protein Data Bank (PDB) by sequence identity and structural quality criteria. Pisces can provide lists culled from the entire PDB or from lists of PDB entries or chains provided by the user. The sequence identities are obtained from PSI-BLAST alignments with position-specific substitution matrices derived from the non-redundant protein sequence database. Pisces therefore provides better lists than servers that use BLAST, which is unable to identify many relationships below 40% sequence identity and often overestimates sequence identity by aligning only well-conserved fragments. PDB sequences are updated weekly. Pisces can also cull non-PDB sequences provided by the user as a list of GenBank identifiers, a FASTA format file, or BLAST/PSI-BLAST output.
