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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
14 Feb 2007-PLOS ONE
TL;DR: The results demonstrate that LoCoH methods are superior to parametric kernel methods in estimating areas used by animals, excluding unused areas (holes) and, generally, in constructing UDs and HRs arising from the movement of animals influenced by hard boundaries and irregular structures.
Abstract: Parametric kernel methods currently dominate the literature regarding the construction of animal home ranges (HRs) and utilization distributions (UDs). These methods frequently fail to capture the kinds of hard boundaries common to many natural systems. Recently a local convex hull (LoCoH) nonparametric kernel method, which generalizes the minimum convex polygon (MCP) method, was shown to be more appropriate than parametric kernel methods for constructing HRs and UDs, because of its ability to identify hard boundaries (e.g., rivers, cliff edges) and convergence to the true distribution as sample size increases. Here we extend the LoCoH in two ways: ‘‘fixed sphere-of-influence,’’ or r-LoCoH (kernels constructed from all points within a fixed radius r of each reference point), and an ‘‘adaptive sphere-of-influence,’’ or a-LoCoH (kernels constructed from all points within a radius a such that the distances of all points within the radius to the reference point sum to a value less than or equal to a), and compare them to the original ‘‘fixed-number-of-points,’’ or k-LoCoH (all kernels constructed from k-1 nearest neighbors of root points). We also compare these nonparametric LoCoH to parametric kernel methods using manufactured data and data collected from GPS collars on African buffalo in the Kruger National Park, South Africa. Our results demonstrate that LoCoH methods are superior to parametric kernel methods in estimating areas used by animals, excluding unused areas (holes) and, generally, in constructing UDs and HRs arising from the movement of animals influenced by hard boundaries and irregular structures (e.g., rocky outcrops). We also demonstrate that a-LoCoH is generally superior to k- and r-LoCoH (with software for all three methods available at http://locoh.cnr.berkeley.edu).

503 citations

Journal ArticleDOI
01 Sep 1986-Icarus
TL;DR: In this paper, the evolution of the giant planets is calculated under the general hypothesis that the solid cores formed first, by accretion of small particles, and that these cores later gravitationally attracted their gaseous envelopes from the solar nebula.

503 citations

Journal ArticleDOI
TL;DR: The origin of a recently discovered close-in Neptune-mass planet around GJ-436 poses a challenge to the current theories of planet formation as discussed by the authors, and it is shown that around M dwarfs, closein NE-mass ice giant planets may be relatively common, while closein Jupiter-mass gas giant planets are relatively rare.
Abstract: The origin of a recently discovered close-in Neptune-mass planet around GJ 436 poses a challenge to the current theories of planet formation. On the basis of the sequential accretion hypothesis and the standard theory of gap formation and orbital migration, we show that around M dwarf stars, close-in Neptune-mass ice giant planets may be relatively common, while close-in Jupiter-mass gas giant planets are relatively rare. The mass distribution of close-in planets generally has two peaks at about Neptune mass and Jupiter mass. The lower mass peak takes the maximum frequency for M dwarfs. Around more massive solar-type stars (G dwarfs), the higher mass peak is much more pronounced. Planets around G dwarfs undergo orbital migration after fully accreting gas, while those around M dwarfs tend to migrate before starting rapid gas accretion. Close-in Neptune-mass planets may also exist around G dwarfs, although they tend to be mostly composed of silicates and iron cores and their frequency is expected to be much smaller than that of Neptune-mass planets around M dwarfs and that of gas giants around G dwarfs. We also show that the conditions for planets' migration due to their tidal interaction with the disk and the stellar mass dependence in the disk mass distribution can be calibrated by the mass distribution of short-period planets around host stars with various masses.

503 citations

Proceedings ArticleDOI
01 May 1998
TL;DR: This paper examines the tractable cases of Boolean constraint-satisfaction problems and shows that they do uniformize, and exhibits three nonuniform tractability results that uniformize and give rise to polynomial-time solvable cases of constraint satisfaction and conjunctive-query containment.
Abstract: Conjunctive-query containment is recognized as a fundamental problem in database query evaluation and optimization. At the same time, constraint satisfaction is recognized as a fundamental problem in artificial intelligence. What do conjunctive-query containment and constraint satisfaction have in common? Our main conceptual contribution in this paper is to point out that, despite their very different formulation, conjunctive-query containment and constraint satisfaction are essentially the same problem. The reason is that they can be recast as the following fundamental algebraic problem: given two finite relational structures A and B, is there a homomorphism h:A?B? As formulated above, the homomorphism problem is uniform in the sense that both relational structures A and B are part of the input. By fixing the structure B, one obtains the following nonuniform problem: given a finite relational structure A, is there a homomorphism h:A?B? In general, nonuniform tractability results do not uniformize. Thus, it is natural to ask: which tractable cases of nonuniform tractability results for constraint satisfaction and conjunctive-query containment do uniformize? Our main technical contribution in this paper is to show that several cases of tractable nonuniform constraint-satisfaction problems do indeed uniformize. We exhibit three nonuniform tractability results that uniformize and, thus, give rise to polynomial-time solvable cases of constraint satisfaction and conjunctive-query containment. We begin by examining the tractable cases of Boolean constraint-satisfaction problems and show that they do uniformize. This can be applied to conjunctive-query containment via Booleanization; in particular, it yields one of the known tractable cases of conjunctive-query containment. After this, we show that tractability results for constraint-satisfaction problems that can be expressed using Datalog programs with bounded number of distinct variables also uniformize. Finally, we provide a new proof for the fact that tractability results for queries with bounded treewidth uniformize as well, via a connection with first-order logic with a bounded number of distinct variables.

502 citations

Journal ArticleDOI
TL;DR: It is suggested that an intermediate level of gene flow will allow the greatest adaptive divergence, owing to genetic/demographic rescue and ‘reinforcement’ and once a certain level of dispersal is reached, it is predicted that a further increase may have negative effects on adaptive divergence.
Abstract: Summary 1Dispersal and gene flow can have a variety of interacting effects on evolution. These effects can either promote or constrain adaptive divergence through either genetic or demographic routes. The relative importance of these effects is unknown because few attempts have been made to conceptually integrate and test them. 2We draw a broad distinction between situations with vs. without strong coevolutionary dynamics. This distinction is important because the adaptive peak for a given population is more mobile in the former than in the latter. This difference makes ongoing evolutionary potential more important in the presence of strong coevolutionary dynamics than in their absence. 3We advance a conceptual integration of the various effects of gene flow and dispersal on adaptive divergence. In line with other authors, but not necessarily for the same reasons, we suggest that an intermediate level of gene flow will allow the greatest adaptive divergence. 4When dispersal is quite low, we predict that an increase will have positive effects on adaptive divergence, owing to genetic/demographic rescue and ‘reinforcement.’ The rescue effect may be more important in small populations and in homogeneous environments. The reinforcement effect may be more common in large populations and in heterogeneous environments. 5Once a certain level of dispersal is reached, we predict that a further increase may have negative effects on adaptive divergence. These effects may arise if carrying capacity is exceeded or maladaptive genes are introduced. 6Many additional effects remain to be integrated into this framework, and doing so may yield novel insights into the factors influencing evolution on ecological time-scales.

502 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