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Institution

University of California, Santa Barbara

EducationSanta Barbara, California, United States
About: University of California, Santa Barbara is a education organization based out in Santa Barbara, California, United States. It is known for research contribution in the topics: Population & Galaxy. The organization has 30281 authors who have published 80852 publications receiving 4626827 citations. The organization is also known as: UC Santa Barbara & UCSB.
Topics: Population, Galaxy, Laser, Quantum well, Quantum dot


Papers
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Journal ArticleDOI
TL;DR: Two major hypotheses for the origin of the latitudinal diversity gradient are reviewed, including the time and area hypothesis and the diversification rate hypothesis, which hold that tropical regions diversify faster due to higher rates of speciation, or due to lower extinction rates.
Abstract: A latitudinal gradient in biodiversity has existed since before the time of the dinosaurs, yet how and why this gradient arose remains unresolved. Here we review two major hypotheses for the origin of the latitudinal diversity gradient. The time and area hypothesis holds that tropical climates are older and historically larger, allowing more opportunity for diversification. This hypothesis is supported by observations that temperate taxa are often younger than, and nested within, tropical taxa, and that diversity is positively correlated with the age and area of geographical regions. The diversification rate hypothesis holds that tropical regions diversify faster due to higher rates of speciation (caused by increased opportunities for the evolution of reproductive isolation, or faster molecular evolution, or the increased importance of biotic interactions), or due to lower extinction rates. There is phylogenetic evidence for higher rates of diversification in tropical clades, and palaeontological data demonstrate higher rates of origination for tropical taxa, but mixed evidence for latitudinal differences in extinction rates. Studies of latitudinal variation in incipient speciation also suggest faster speciation in the tropics. Distinguishing the roles of history, speciation and extinction in the origin of the latitudinal gradient represents a major challenge to future research.

1,435 citations

Journal ArticleDOI
TL;DR: In this article, it was shown that non-Abelian gauge fields arise in the adiabatic development of simple quantum mechanical systems and are related to energy splittings, which may be observable in real systems.
Abstract: Generalizing a construction of Berry and Simon, we show that non-Abelian gauge fields arise in the adiabatic development of simple quantum mechanical systems. Characteristics of the gauge fields are related to energy splittings, which may be observable in real systems. Similar phenomena are found for suitable classical systems.

1,432 citations

Journal ArticleDOI
03 Sep 1993-Science
TL;DR: Model Q230 proposed by Mariani and his co-workers satisfactorily fits the x-ray data collected on the cubic mesostructure material and suggests that the silicate polymer forms a unique infinite silicate sheet sitting on the gyroid minimal surface and separating the surfactant molecules into two disconnected volumes.
Abstract: A model is presented to explain the formation and morphologies of surfactant-silicate mesostructures. Three processes are identified: multidentate binding of silicate oligomers to the cationic surfactant, preferential silicate polymerization in the interface region, and charge density matching between the surfactant and the silicate. The model explains present experimental data, including the transformation between lamellar and hexagonal mesophases, and provides a guide for predicting conditions that favor the formation of lamellar, hexagonal, or cubic mesostructures. Model Q(230) proposed by Mariani and his co-workers satisfactorily fits the x-ray data collected on the cubic mesostructure material. This model suggests that the silicate polymer forms a unique infinite silicate sheet sitting on the gyroid minimal surface and separating the surfactant molecules into two disconnected volumes.

1,431 citations

Journal ArticleDOI
TL;DR: In this article, a mathematical framework for cyber-physical systems, attacks, and monitors is proposed, and fundamental monitoring limitations from both system-theoretic and graph-based perspectives are characterized.
Abstract: Cyber-physical systems are ubiquitous in power systems, transportation networks, industrial control processes, and critical infrastructures. These systems need to operate reliably in the face of unforeseen failures and external malicious attacks. In this paper: (i) we propose a mathematical framework for cyber-physical systems, attacks, and monitors; (ii) we characterize fundamental monitoring limitations from system-theoretic and graph-theoretic perspectives; and (ii) we design centralized and distributed attack detection and identification monitors. Finally, we validate our findings through compelling examples.

1,430 citations

Book
28 Oct 2002
TL;DR: In this thoroughly revised edition of the bestselling e-Learning and the Science of Instruction authors Ruth Colvin Clark and Richard E. Mayer offer essential information and guidelines for selecting, designing, and developing asynchronous and synchronous e-learning courses that build knowledge and skills for workers learning in corporate, government, and academic settings.
Abstract: In this thoroughly revised edition of the bestselling e-Learning and the Science of Instruction authors Ruth Colvin Clark and Richard E. Mayer internationally-recognized experts in the field of e-learningoffer essential information and guidelines for selecting, designing, and developing asynchronous and synchronous e-learning courses that build knowledge and skills for workers learning in corporate, government, and academic settings. In addition to updating research in all chapters, two new chapters and a CD with multimedia examples are included.

1,430 citations


Authors

Showing all 30652 results

NameH-indexPapersCitations
George M. Whitesides2401739269833
Yi Chen2174342293080
Simon D. M. White189795231645
George Efstathiou187637156228
Peidong Yang183562144351
David R. Williams1782034138789
Alan J. Heeger171913147492
Richard H. Friend1691182140032
Jiawei Han1681233143427
Gang Chen1673372149819
Alexander S. Szalay166936145745
Omar M. Yaghi165459163918
Carlos S. Frenk165799140345
Yang Yang1642704144071
Carlos Bustamante161770106053
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Performance
Metrics
No. of papers from the Institution in previous years
YearPapers
20241
2023150
2022528
20213,351
20203,653
20193,516