University of California, Irvine

About: University of California, Irvine is a education organization based out in Irvine, California, United States. It is known for research contribution in the topics: Population & Galaxy. The organization has 47031 authors who have published 113602 publications receiving 5521832 citations. The organization is also known as: UC Irvine & UCI.

Tempo and mode in evolution.

Abstract: George Gaylord Simpson said in his classic Tempo and Mode in Evolution (1) that paleontologists enjoy special advantages over geneticists on two evolutionary topics. One general topic, suggested by the word "tempo," has to do with "evolutionary rates. . ., their acceleration and deceleration, the conditions of exceptionally slow or rapid evolutions, and phenomena suggestive of inertia and momentum." A group of related problems, implied by the word "mode," involves "the study of the way, manner, or pattern of evolution, a study in which tempo is a basic factor, but which embraces considerably more than tempo" (pp. xvii-xviii). Simpson's book was self-consciously written in the wake of Theodosius Dobzhansky's Genetics and the Origin of Species (2). The title of Dobzhansky's book suggested its theme: the role of genetics in explaining "the origin of species"-i.e., a synthesis of Darwin's theory of evolution by natural selection and the maturing science of genetics. In the introduction to his book, Simpson averred that an essential part of his study was an "attempted synthesis of paleontology and genetics," an effort that pervaded the whole book, but was particularly the subject of the first two chapters, which accounted for nearly half the book's pages. Darwin believed that evolutionary change occurs by natural selection of small individual differences appearing every generation within any species. Singly the changes effected by selection are small but, given enough time, great changes can take place. Two of Darwin's most dedicated supporters, Thomas Huxley and Francis Galton, argued instead that evolution occurs by selection of discontinuous variations, or sports; evolution proceeds rapidly by discrete leaps. According to Huxley, if natural selection operates only upon gradual differences among individuals, the gaps between existing species and in the paleontological record could not be explained. For Galton, evolution was not a smooth and uniform process, but proceeded by "jerks," some of which imply considerable organic change. This controversy was continued in the latter part of the nineteenth century by the biometricians Karl Pearson and W. F. R. Weldon, who believed, like Darwin, in the primary importance of common individual differences, and by the geneticist William Bateson, who maintained the primary importance of discontinuous variations. The rediscovery of Mendelian inheritance in 1900 provided what might have been common grounds to resolve the conflict. Instead, the dispute between biometricians and geneticists extended to continental Europe and to the United States. Bateson was the champion of the Mendelians, many of whom accepted the mutation theory proposed by De Vries, and denied that natural selection played a major role in evolution. The biometricians for their part argued that Mendelian characters were sports of little importance to the evolutionary process.

Space-Time Coding: Theory and Practice

Abstract: This book covers the fundamental principles of space-time coding for wireless communications over multiple-input multiple-output (MIMO) channels, and sets out practical coding methods for achieving the performance improvements predicted by the theory. The theory and practice sections can be used independently of each other. Written by one of the inventors of space-time block coding, this volume is ideal for a graduate student familiar with the basics of digital communications, and for engineers implementing the theory in real systems.

Baryon acoustic oscillations in the Lyα forest of BOSS DR11 quasars

Abstract: We report a detection of the baryon acoustic oscillation (BAO) feature in the flux-correlation function of the Ly forest of high-redshift quasars with a statistical significance of five standard deviations The study uses 137,562 quasars in the redshift range 2:1 z 3:5 from the Data Release 11 (DR11) of the Baryon Oscillation Spectroscopic Survey (BOSS) of SDSS-III This sample contains three times the number of quasars used in previous studies The measured position of the BAO peak determines the angular distance, DA(z = 2:34) and expansion rate, H(z = 2:34), both on a scale set by the sound horizon at the drag epoch, rd We find DA=rd =

Potential role of ultrafine particles in associations between airborne particle mass and cardiovascular health.

Abstract: Numerous epidemiologic time-series studies have shown generally consistent associations of cardiovascular hospital admissions and mortality with outdoor air pollution, particularly mass concentrations of particulate matter (PM) < or = 2.5 or < or = 10 microm in diameter (PM2.5, PM10). Panel studies with repeated measures have supported the time-series results showing associations between PM and risk of cardiac ischemia and arrhythmias, increased blood pressure, decreased heart rate variability, and increased circulating markers of inflammation and thrombosis. The causal components driving the PM associations remain to be identified. Epidemiologic data using pollutant gases and particle characteristics such as particle number concentration and elemental carbon have provided indirect evidence that products of fossil fuel combustion are important. Ultrafine particles < 0.1 microm (UFPs) dominate particle number concentrations and surface area and are therefore capable of carrying large concentrations of adsorbed or condensed toxic air pollutants. It is likely that redox-active components in UFPs from fossil fuel combustion reach cardiovascular target sites. High UFP exposures may lead to systemic inflammation through oxidative stress responses to reactive oxygen species and thereby promote the progression of atherosclerosis and precipitate acute cardiovascular responses ranging from increased blood pressure to myocardial infarction. The next steps in epidemiologic research are to identify more clearly the putative PM casual components and size fractions linked to their sources. To advance this, we discuss in a companion article (Sioutas C, Delfino RJ, Singh M. 2005. Environ Health Perspect 113:947-955) the need for and methods of UFP exposure assessment.