The University of California, Santa Barbara is a public research university and one of the 10 general campuses of the University of California system. The main campus is located on a 1,022-acre site near Goleta, California, United States, 8 miles from Santa Barbara and 100 miles northwest of Los Angeles. Tracing its roots back to 1891 as an independent teachers' college, UCSB joined the University of California system in 1944 and is the third-oldest general-education campus in the system.UCSB is one of America's Public Ivy universities, which recognizes top public research universities in the United States. The university is a comprehensive doctoral university and is organized into five colleges and schools offering 87 undergraduate degrees and 55 graduate degrees. UCSB was ranked 40th among "National Universities", 10th among U.S. public universities and 28th among Best Global Universities by U.S. News & World Report 's 2015 rankings. The university was also ranked 37th worldwide by the Times Higher Education World University Rankings and 41st worldwide by the Academic Ranking of World Universities in 2014.UC Santa Barbara is a "very high activity" research university and spent $233.9 million on research expenditures in the 2012 fiscal year, 91st largest in the United States. UCSB houses twelve national research centers, including the renowned Kavli Institute for Theoretical Physics. Current UCSB faculty includes six Nobel Prize laureates, one Fields Medalist, 29 members of the National Academy of science, 27 members of the National Academy of Engineering, and 31 members of the American Academy of Arts and science. UCSB was the No. 3 host on the ARPAnet and was elected to the Association of American Universities in 1995.The UC Santa Barbara Gauchos compete in the Big West Conference of the NCAA Division I. The Gauchos have won NCAA national championships in men's soccer and men's water polo. Wikipedia.
Tilman D.,University of California at Santa Barbara |
Clark M.,University of Minnesota
Nature | Year: 2014
Diets link environmental and human health. Rising incomes and urbanization are driving a global dietary transition in which traditional diets are replaced by diets higher in refined sugars, refined fats, oils and meats. By 2050 these dietary trends, if unchecked, would be a major contributor to an estimated 80 per cent increase in global agricultural greenhouse gas emissions from food production and to global land clearing. Moreover, these dietary shifts are greatly increasing the incidence of type II diabetes, coronary heart disease and other chronic non-communicable diseases that lower global life expectancies. Alternative diets that offer substantial health benefits could, if widely adopted, reduce global agricultural greenhouse gas emissions, reduce land clearing and resultant species extinctions, and help prevent such diet-related chronic non-communicable diseases. The implementation of dietary solutions to the tightly linked diet-environment-health trilemma is a global challenge, and opportunity, of great environmental and public health importance.
Treu T.,University of California at Santa Barbara
Annual Review of Astronomy and Astrophysics | Year: 2010
Strong lensing is a powerful tool to address three majorastrophysical issues: understanding the spatial distribution of mass at kiloparsec and subkiloparsec scale, where baryons and dark matter interact to shape galaxies as we see them; determining the overall geometry, content, and kinematics of the Universe; and studying distant galaxies, black holes, and active nuclei that are too small or too faint to be resolved or detected with current instrumentation. After summarizing strong gravitational lensing fundamentals, I present a selection of recent important results. I conclude by discussing the exciting prospects of strong gravitational lensing in the nextdecade. © 2010 by Annual Reviews.
Zhang L.,University of California at Santa Barbara
Accounts of Chemical Research | Year: 2014
For the past dozen years, homogeneous gold catalysis has evolved from a little known topic in organic synthesis to a fully blown research field of significant importance to synthetic practitioners, due to its novel reactivities and reaction modes. Cationic gold(I) complexes are powerful soft Lewis acids that can activate alkynes and allenes toward efficient attack by nucleophiles, leading to the generation of alkenyl gold intermediates. Some of the most versatile aspects of gold catalysis involve the generation of gold carbene intermediates, which occurs through the approach of an electrophile to the distal end of the alkenyl gold moiety, and their diverse transformations thereafter. On the other hand, α-oxo metal carbene/carbenoids are highly versatile intermediates in organic synthesis and can undergo various synthetically challenging yet highly valuable transformations such as C-H insertion, ylide formation, and cyclopropanation reactions. Metal-catalyzed dediazotizations of diazo carbonyl compounds are the principle and most reliable strategy to access them. Unfortunately, the substrates contain a highly energetic diazo moiety and are potentially explosive. Moreover, chemists need to use energetic reagents to prepare them, putting further constrains on operational safety.In this Account, we show that the unique access to the gold carbene species in homogeneous gold catalysis offers an opportunity to generate α-oxo gold carbenes if both nucleophile and electrophile are oxygen. Hence, this approach would enable readily available and safer alkynes to replace hazardous α-diazo carbonyl compounds as precursors in the realm of gold carbene chemistry.For the past several years, we have demonstrated that alkynes can indeed effectively serve as precursors to versatile α-oxo gold carbenes. In our initial study, we showed that a tethered sulfoxide can be a suitable oxidant, which in some cases leads to the formation of α-oxo gold carbene intermediates. The intermolecular approach offers excellent synthetic flexibility because no tethering of the oxidant is required, and its reduced form is not tangled with the product. We were the first research group to develop this strategy, through the use of pyridine/quinolone N-oxides as the external oxidants. In this manner, we can effectively make a C-C triple bond a surrogate of an α-diazo carbonyl moiety in various gold catalyses. With terminal alkynes, we demonstrated that we can efficiently trap exclusively formed terminal carbene centers by internal nucleophiles en route to the formation of cyclic products, including strained oxetan-3-ones and azetidin-3-ones, and by external nucleophiles when a P,N-bidentate ligand is coordinated to gold. With internal alkynes, we generated synthetically useful regioselectivities in the generation of the α-oxo gold carbene moiety, which enables expedient formation of versatile enone products. Other research groups have also applied this strategy en route to versatile synthetic methods. The α-oxo gold carbenes appear to be more electrophilic than their Rh counterpart, which many chemists have focused on in a large array of excellent work on metal carbene chemistry. The ease of accessing the reactive gold carbenes opens up a vast area for developing new synthetic methods that would be distinctively different from the known Rh chemistry and promises to generate a new round of "gold rush". © 2014 American Chemical Society.
Heeger A.J.,University of California at Santa Barbara
Advanced Materials | Year: 2014
The status of understanding of the operation of bulk heterojunction (BHJ) solar cells is reviewed. Because the carrier photoexcitation recombination lengths are typically 10 nm in these disordered materials, the length scale for self-assembly must be of order 10-20 nm. Experiments have verified the existence of the BHJ nanostructure, but the morphology remains complex and a limiting factor. Three steps are required for generation of electrical power: i) absorption of photons from the sun; ii) photoinduced charge separation and the generation of mobile carriers; iii) collection of electrons and holes at opposite electrodes. The ultrafast charge transfer process arises from fundamental quantum uncertainty; mobile carriers are directly generated (electrons in the acceptor domains and holes in the donor domains) by the ultrafast charge transfer (≈70%) with ≈30% generated by exciton diffusion to a charge separating heterojunction. Sweep-out of the mobile carriers by the internal field prior to recombination is essential for high performance. Bimolecular recombination dominates in materials where the donor and acceptor phases are pure. Impurities degrade performance by introducing Shockly-Read-Hall decay. The review concludes with a summary of the problems to be solved to achieve the predicted power conversion efficiencies of >20% for a single cell. The operation of bulk heterojunction (BHJ) solar cells is reviewed. Ultrafast charge transfer arises from fundamental quantum uncertainty as expressed by the uncertainty principle; mobile charges are generated directly by ultrafast charge transfer. Sweep-out of the mobile carriers by the internal field prior to recombination is essential to obtain a high performance, especially a high fill factor. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Langer J.S.,University of California at Santa Barbara
Reports on Progress in Physics | Year: 2014
This key-issues review is a plea for a new focus on simpler and more realistic models of glass-forming fluids. It seems to me that we have too often been led astray by sophisticated mathematical models that beautifully capture some of the most intriguing features of glassy behavior, but are too unrealistic to provide bases for predictive theories. As illustrations of what I mean, the first part of this article is devoted to brief summaries of imaginative, sensible, but disparate and often contradictory ideas for solving glass problems. Almost all of these ideas remain alive today, with their own enthusiastic advocates. I then describe numerical simulations, mostly by H Tanaka and coworkers, in which it appears that very simple, polydisperse systems of hard disks and spheres develop long range, Ising-like, bond-orientational order as they approach glass transitions. Finally, I summarize my recent proposal that topologically ordered clusters of particles, in disordered environments, tend to become aligned with each other as if they were two-state systems, and thus produce the observed Ising-like behavior. Neither Tanaka's results nor my proposed interpretation of them fit comfortably within any of the currently popular glass theories. © 2014 IOP Publishing Ltd.
Heeger A.J.,University of California at Santa Barbara
Chemical Society Reviews | Year: 2010
There has been remarkable progress in the science and technology of semiconducting polymers during the past decade. The field has evolved from the early work on polyacetylene (the First Generation material) to a proper focus on soluble and processible polymers and co-polymers. The soluble poly(alkylthiophenes) and the soluble PPVs are perhaps the most important examples of the Second Generation of semiconducting polymers. Third Generation semiconducting polymers have more complex molecular structures with more atoms in the repeat unit. Important examples include the highly ordered and crystalline PDTTT and the ever-growing class of donor-acceptor co-polymers that has emerged in the past few years. Examples of the latter include the bithiophene-acceptor co-polymers pioneered by Konarka and the polycarbazole-acceptor co-polymers pioneered by Leclerc and colleagues. In this tutorial review, I will summarize progress in the basic physics, the materials science, the device science and the device performance with emphasis on the following recent studies of Third Generation semiconducting polymers: stable semiconducting polymers; self-assembly of bulk heterojunction (BHJ) materials by spontaneous phase separation; bulk heterojunction solar cells with internal quantum efficiency approaching 100%; high detectivity photodetectors fabricated from BHJ materials. © 2010 The Royal Society of Chemistry.
Qi X.-L.,University of California at Santa Barbara |
Qi X.-L.,Stanford University |
Zhang S.-C.,Stanford University
Reviews of Modern Physics | Year: 2011
Topological insulators are new states of quantum matter which cannot be adiabatically connected to conventional insulators and semiconductors. They are characterized by a full insulating gap in the bulk and gapless edge or surface states which are protected by time-reversal symmetry. These topological materials have been theoretically predicted and experimentally observed in a variety of systems, including HgTe quantum wells, BiSb alloys, and Bi 2Te3 and Bi2Se3 crystals. Theoretical models, materials properties, and experimental results on two-dimensional and three-dimensional topological insulators are reviewed, and both the topological band theory and the topological field theory are discussed. Topological superconductors have a full pairing gap in the bulk and gapless surface states consisting of Majorana fermions. The theory of topological superconductors is reviewed, in close analogy to the theory of topological insulators. © 2011 American Physical Society.
Brown F.L.H.,University of California at Santa Barbara
Quarterly Reviews of Biophysics | Year: 2011
Traditional particle-based simulation strategies are impractical for the study of lipid bilayers and biological membranes over the longest length and time scales (microns, seconds and longer) relevant to cellular biology. Continuum-based models developed within the frameworks of elasticity theory, fluid dynamics and statistical mechanics provide a framework for studying membrane biophysics over a range of mesoscopic to macroscopic length and time regimes, but the application of such ideas to simulation studies has occurred only relatively recently. We review some of our efforts in this direction with emphasis on the dynamics in model membrane systems. Several examples are presented that highlight the prominent role of hydrodynamics in membrane dynamics and we argue that careful consideration of fluid dynamics is key to understanding membrane biophysics at the cellular scale. © 2011 Cambridge University Press.
Mezic I.,University of California at Santa Barbara
Annual Review of Fluid Mechanics | Year: 2013
This article reviews theory and applications of Koopman modes in fluid mechanics. Koopman mode decomposition is based on the surprising fact, discovered in Mezić (2005), that normal modes of linear oscillations have their natural analogs-Koopman modes-in the context of nonlinear dynamics. To pursue this analogy, one must change the representation of the system from the state-space representation to the dynamics governed by the linear Koopman operator on an infinite-dimensional space of observables. Whereas Koopman in his original paper dealt only with measure-preserving transformations, the discussion here is predominantly on dissipative systems arising from Navier-Stokes evolution. The analysis is based on spectral properties of the Koopman operator. Aspects of point and continuous parts of the spectrum are discussed. The point spectrum corresponds to isolated frequencies of oscillation present in the fluid flow, and also to growth rates of stable and unstable modes. The continuous part of the spectrum corresponds to chaotic motion on the attractor. A method of computation of the spectrum and the associated Koopman modes is discussed in terms of generalized Laplace analysis. When applied to a generic observable, this method uncovers the full point spectrum. A computational alternative is given by Arnoldi-type methods, leading to so-called dynamic mode decomposition, and I discuss the connection and differences between these two methods. A number of applications are reviewed in which decompositions of this type have been pursued. Koopman mode theory unifies and provides a rigorous background for a number of different concepts that have been advanced in fluid mechanics, including global mode analysis, triple decomposition, and dynamic mode decomposition. Copyright © 2013 by Annual Reviews. All rights reserved.
Scalapino D.J.,University of California at Santa Barbara
Reviews of Modern Physics | Year: 2012
The structures, the phase diagrams, and the appearance of a neutron resonance signaling an unconventional superconducting state provide phenomenological evidence relating the cuprates, the Fe-pnictides and chalcogenides as well as some heavy-fermion and actinide materials. Single-band and multiband Hubbard models have been found to describe a number of the observed properties of these materials so that it is reasonable to examine the origin of the pairing interaction in these models. In this review, based on the experimental phenomenology and studies of the pairing interaction for Hubbard-like models, it is proposed that spin-fluctuation mediated pairing is the common thread linking a broad class of superconducting materials. © 2012 American Physical Society.