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Institution

University of California, Santa Cruz

EducationSanta Cruz, California, United States
About: University of California, Santa Cruz is a education organization based out in Santa Cruz, California, United States. It is known for research contribution in the topics: Galaxy & Population. The organization has 15541 authors who have published 44120 publications receiving 2759983 citations. The organization is also known as: UCSC & UC, Santa Cruz.
Topics: Galaxy, Population, Star formation, Redshift, Planet


Papers
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Journal ArticleDOI
TL;DR: The normalized and signed gradient dynamical systems associated with a differentiable function are characterized and their asymptotic convergence properties are identified and conditions that guarantee finite-time convergence are identified.

779 citations

Journal ArticleDOI
22 Nov 1996-Science
TL;DR: The structure of the RNA-paromomycin complex explains binding of diverse aminoglycosides to the ribosome, their specific activity against prokaryotic organisms, and various resistance mechanisms, and provides insight into ribosomes function.
Abstract: Aminoglycoside antibiotics that bind to 30S ribosomal A-site RNA cause misreading of the genetic code and inhibit translocation. The aminoglycoside antibiotic paromomycin binds specifically to an RNA oligonucleotide that contains the 30S subunit A site, and the solution structure of the RNA-paromomycin complex was determined by nuclear magnetic resonance spectroscopy. The antibiotic binds in the major groove of the model A-site RNA within a pocket created by an A-A base pair and a single bulged adenine. Specific interactions occur between aminoglycoside chemical groups important for antibiotic activity and conserved nucleotides in the RNA. The structure explains binding of diverse aminoglycosides to the ribosome, their specific activity against prokaryotic organisms, and various resistance mechanisms, and provides insight into ribosome function.

778 citations

Journal ArticleDOI
TL;DR: This paper describes two prior classes, analysis-based and synthesis-based, and shows that although when reducing to the complete and under-complete formulations the two become equivalent, in their more interesting overcomplete formulation the two types depart.
Abstract: The concept of prior probability for signals plays a key role in the successful solution of many inverse problems. Much of the literature on this topic can be divided between analysis-based and synthesis-based priors. Analysis-based priors assign probability to a signal through various forward measurements of it, while synthesis-based priors seek a reconstruction of the signal as a combination of atom signals. The algebraic similarity between the two suggests that they could be strongly related; however, in the absence of a detailed study, contradicting approaches have emerged. While the computationally intensive synthesis approach is receiving ever-increasing attention and is notably preferred, other works hypothesize that the two might actually be much closer, going as far as to suggest that one can approximate the other. In this paper we describe the two prior classes in detail, focusing on the distinction between them. We show that although in the simpler complete and undercomplete formulations the two approaches are equivalent, in their overcomplete formulation they depart. Focusing on the l1 case, we present a novel approach for comparing the two types of priors based on high-dimensional polytopal geometry. We arrive at a series of theoretical and numerical results establishing the existence of an unbridgeable gap between the two.

777 citations

Journal ArticleDOI
TL;DR: The DEEP2 Galaxy Redshift Survey (DEEP2) as discussed by the authors is the largest high-precision redshift survey of galaxies at z ~ 1 completed to date, covering an area of 2.8 deg^2 divided into four separate fields observed to a limiting apparent magnitude of R_(AB) = 24.1.
Abstract: We describe the design and data analysis of the DEEP2 Galaxy Redshift Survey, the densest and largest high-precision redshift survey of galaxies at z ~ 1 completed to date. The survey was designed to conduct a comprehensive census of massive galaxies, their properties, environments, and large-scale structure down to absolute magnitude M_B = −20 at z ~ 1 via ~90 nights of observation on the Keck telescope. The survey covers an area of 2.8 deg^2 divided into four separate fields observed to a limiting apparent magnitude of R_(AB) = 24.1. Objects with z ≾0.7 are readily identifiable using BRI photometry and rejected in three of the four DEEP2 fields, allowing galaxies with z > 0.7 to be targeted ~2.5 times more efficiently than in a purely magnitude-limited sample. Approximately 60% of eligible targets are chosen for spectroscopy, yielding nearly 53,000 spectra and more than 38,000 reliable redshift measurements. Most of the targets that fail to yield secure redshifts are blue objects that lie beyond z ~ 1.45, where the [O ii] 3727 A doublet lies in the infrared. The DEIMOS 1200 line mm^(−1) grating used for the survey delivers high spectral resolution (R ~ 6000), accurate and secure redshifts, and unique internal kinematic information. Extensive ancillary data are available in the DEEP2 fields, particularly in the Extended Groth Strip, which has evolved into one of the richest multiwavelength regions on the sky. This paper is intended as a handbook for users of the DEEP2 Data Release 4, which includes all DEEP2 spectra and redshifts, as well as for the DEEP2 DEIMOS data reduction pipelines. Extensive details are provided on object selection, mask design, biases in target selection and redshift measurements, the spec2d two-dimensional data-reduction pipeline, the spec1d automated redshift pipeline, and the zspec visual redshift verification process, along with examples of instrumental signatures or other artifacts that in some cases remain after data reduction. Redshift errors and catastrophic failure rates are assessed through more than 2000 objects with duplicate observations. Sky subtraction is essentially photon-limited even under bright OH sky lines; we describe the strategies that permitted this, based on high image stability, accurate wavelength solutions, and powerful B-spline modeling methods. We also investigate the impact of targets that appear to be single objects in ground-based targeting imaging but prove to be composite in Hubble Space Telescope data; they constitute several percent of targets at z ~ 1, approaching ~5%–10% at z > 1.5. Summary data are given that demonstrate the superiority of DEEP2 over other deep high-precision redshift surveys at z ~ 1 in terms of redshift accuracy, sample number density, and amount of spectral information. We also provide an overview of the scientific highlights of the DEEP2 survey thus far.

776 citations

Journal ArticleDOI
TL;DR: An option is a priori to combine sources with similar signatures so the number of sources is small enough to provide a unique solution, and contributions from functionally related groups of sources can be summed a posteriori, producing a range of solutions for the aggregate source that may be considerably narrower.
Abstract: Stable isotope mixing models are often used to quantify source contributions to a mixture. Examples include pollution source identification; trophic web studies; analysis of water sources for soils, plants; or water bodies, and many others. A common problem is having too many sources to allow a unique solution. We discuss two alternative procedures for addressing this problem. One option is a priori to combine sources with similar signatures so the number of sources is small enough to provide a unique solution. Aggregation should be considered only when isotopic signatures of clustered sources are not significantly different, and sources are related so the combined source group has some functional significance. For example, in a food web analysis, lumping several species within a trophic guild allows more interpretable results than lumping disparate food sources, even if they have similar isotopic signatures. One result of combining mixing model sources is increased uncertainty of the combined end-member isotopic signatures and consequently the source contribution estimates; this effect can be quantified using the IsoError model ( http://www.epa.gov/wed/pages/models/isotopes/isoerror1_04.htm ). As an alternative to lumping sources before a mixing analysis, the IsoSource mixing model ( http://www.epa.gov/wed/pages/models/isosource/isosource.htm ) can be used to find all feasible solutions of source contributions consistent with isotopic mass balance. While ranges of feasible contributions for each individual source can often be quite broad, contributions from functionally related groups of sources can be summed a posteriori, producing a range of solutions for the aggregate source that may be considerably narrower. A paleohuman dietary analysis example illustrates this method, which involves a terrestrial meat food source, a combination of three terrestrial plant foods, and a combination of three marine foods. In this case, a posteriori aggregation of sources allowed strong conclusions about temporal shifts in marine versus terrestrial diets that would not have otherwise been discerned.

775 citations


Authors

Showing all 15733 results

NameH-indexPapersCitations
David J. Schlegel193600193972
David R. Williams1782034138789
John R. Yates1771036129029
David Haussler172488224960
Evan E. Eichler170567150409
Anton M. Koekemoer1681127106796
Mark Gerstein168751149578
Alexander S. Szalay166936145745
Charles M. Lieber165521132811
Jorge E. Cortes1632784124154
M. Razzano155515106357
Lars Hernquist14859888554
Aaron Dominguez1471968113224
Taeghwan Hyeon13956375814
Garth D. Illingworth13750561793
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Performance
Metrics
No. of papers from the Institution in previous years
YearPapers
202351
2022328
20212,157
20202,353
20192,209
20182,157