Sanford Selznick
A5042317934- Astro and Planetary Science
- Planetary Science and Exploration
- Vitamin D Research Studies
- Isotope Analysis in Ecology
- Spacecraft and Cryogenic Technologies
- Estrogen and related hormone effects
- Stellar, planetary, and galactic studies
- Spacecraft Design and Technology
- Retinoids in leukemia and cellular processes
- Distributed and Parallel Computing Systems
- Adaptive optics and wavefront sensing
- Astronomy and Astrophysical Research
- Atmospheric Ozone and Climate
- Algorithms and Data Compression
- Calibration and Measurement Techniques
- Growth Hormone and Insulin-like Growth Factors
- Gamma-ray bursts and supernovae
- Fluid Dynamics Simulations and Interactions
- Photocathodes and Microchannel Plates
- Experimental and Theoretical Physics Studies
- Space Satellite Systems and Control
- Earthquake Detection and Analysis
- Genomics and Phylogenetic Studies
- High-pressure geophysics and materials
- Astrophysics and Star Formation Studies
University of Arizona
1996-2024
Planetary Science Institute
2018-2022
Software (Spain)
2001
Active asteroids are those that show evidence of ongoing mass loss. We report repeated instances particle ejection from the surface (101955) Bennu, demonstrating it is an active asteroid. The events were imaged by OSIRIS-REx (Origins, Spectral Interpretation, Resource Identification, and Security-Regolith Explorer) spacecraft. For three largest observed events, we estimated ejected velocities sizes, event times, source regions, energies. also determined trajectories photometric properties...
The OSIRIS-REx Camera Suite (OCAMS) will acquire images essential to collecting a sample from the surface of Bennu. During proximity operations, these document presence satellites and plumes, record spin state, enable an accurate model asteroid's shape, identify any hazards. They confirm sampleable regolith on surface, observe sampling event itself, image head in order verify its readiness be stowed. Bennu's history as example early solar system material, microgravity body with planetesimal...
Carbonaceous asteroids, such as (101955) Bennu, preserve material from the early Solar System, including volatile compounds and organic molecules. We report spacecraft imaging spectral data collected during after retrieval of a sample Bennu’s surface. The sampling event mobilized rocks dust into debris plume, excavating 9-meter-long elliptical crater. This exposed is darker, spectrally redder, more abundant in fine particulates than original bulk density displaced subsurface was 500 to 700...
When the OSIRIS-REx spacecraft pressed its sample collection mechanism into surface of Bennu, it provided a direct test poorly understood near-subsurface physical properties rubble-pile asteroids, which consist rock fragments at rest in microgravity. Here, we find that forces measured by are best modeled as granular bed with near-zero cohesion is half dense bulk asteroid. The low gravity small asteroid such Bennu effectively weakens near subsurface not compressing upper layers, thereby...
Abstract We analyze the trajectories of 313 particles seen in near‐Bennu environment between December 2018 and September 2019. Of these, 65% follow suborbital trajectories, 20% undergo more than one orbital revolution around asteroid, 15% directly escape on hyperbolic trajectories. The median lifetime these is ∼6 hr. are sensitive to Bennu's gravitational field, which allows us reliably estimate spherical harmonic coefficients through degree 8 resolve nonuniform mass distribution 3....
Hereditary hypocalcemic vitamin D-resistant rickets is attributable to defects in the nuclear receptor for 1,25-dihydroxyvitamin D3 [1,25-(OH)2D3]. Two novel point mutations (I314S and R391C) identified hormone-binding domain of human D (VDR) from patients with hereditary confer sharply reduced 1,25-(OH)2D3-dependent transactivation. These natural mutations, especially R391C, also lead a second specific consequence, namely impaired heterodimeric interaction retinoid X (RXR). While...
Abstract Near‐Earth asteroid (101955) Bennu is an active experiencing mass loss in the form of ejection events emitting up to hundreds millimeter‐ centimeter‐scale particles. The close proximity Origins, Spectral Interpretations, Resource Identification, and Security–Regolith Explorer spacecraft enabled monitoring particles for a 10‐month period encompassing Bennu's perihelion aphelion. We found 18 multiparticle events, with masses ranging from near zero grams (or thousands uncertainties)...
Article Free Access Share on Progressive multiple alignment with constraints Authors: Gene Myers Department of Computer Science, University Arizona, Tucson, AZ AZView Profile , Sanford Selznick Zheng Zhang Science and Engineering, The Pennsylvania State University, Park, PA PAView Webb Miller Authors Info & Claims RECOMB '97: Proceedings the first annual international conference Computational molecular biologyJanuary 1997 Pages 220–225https://doi.org/10.1145/267521.267758Published:19 January...
A progressive alignment algorithm produces a multialignment of set sequences by repeatedly aligning pairs and/or previously generated alignments. We describe method for guaranteeing that the strategy satisfies user-specified collection constraints about where certain sequence positions should appear relative to others. Our main result is an compute just "prime" are implied user-given constraints; these shown be precisely must obey. In practice, time required handle negligible and frequently...
Aspera is an extreme-UV (EUV) Astrophysics small satellite telescope designed to map the warm-hot phase coronal gas around nearby galaxy halos. Theory suggests that this a significant fraction of galaxy's halo mass and plays critical role in its evolution, but exact poorly understood. observes via Ovi emission at 1032 °A using four parallel Rowland-Circle-like spectrograph channels single payload. Aspera's robust-and-simple design inspired by FUSE spectrograph, with smaller, 6.2 cm × 3.7 cm,...
Abstract We searched for an optimized protocol mapping observations from a point spectrometer onto shape model composed of triangular facets, in the context NASA's asteroid sample return mission, OSIRIS‐REx (Origins, Spectral Interpretation, Resource Identification, and Security‐Regolith Explorer). Our study was conducted before spacecraft arrived at mission target (101955) Bennu, we used observational sequence plans Visible InfraRed Spectrometer (OVIRS). explored six methods data to using...
Aspera is a NASA-funded UV SmallSat Mission in development with projected launch 2025. The goal of the mission to detect and map warm-hot gas circumgalactic medium nearby galaxies traced by Ovi emission line at 103.2 nm. To that goal, will conduct long-exposure observations one or more spatial fields around each target galaxy, employing two long-slit spectrographs. Spectra from both channels are focused on single micro-channel plate detector. In preparation mission's launch, we developing...
Aspera is a NASA-funded UV SmallSat mission designed to detect and map warm-hot phase halo gas around nearby galaxies. The payload faint diffuse O VI emission at 103.2 nm, satisfying the sensitivity requirement of 5×10<sup>−19</sup> erg/s/cm<sup>2</sup>/arcsec<sup>2</sup> over 179 hours exposure. In this manuscript, we describe overall design Aspera. comprises two identical co-aligned long-slit spectrograph optical channels sharing common UV-sensitive microchannel plate detector. delivers...
Aspera is a NASA Astrophysics Pioneers SmallSat mission designed to study diffuse OVI emission from the warm-hot phase gas in halos of nearby galaxies. Its payload consists two identical Rowland Circle-type long-slit spectrographs, sharing single MicroChannel plate detector. Each spectrograph channel an off-axis parabola primary mirror and toroidal diffraction grating optimized for 1013-1057 Angstroms bandpass. Despite simple configuration, optical alignment/integration process challenging...