University of Rochester

About: University of Rochester is a education organization based out in Rochester, New York, United States. It is known for research contribution in the topics: Population & Laser. The organization has 63915 authors who have published 112762 publications receiving 5484122 citations. The organization is also known as: Rochester University.

The Population Genetics of Speciation: The Evolution of Hybrid Incompatibilities

Abstract: Speciation often results from the accumulation of "complementary genes," i.e., from genes that, while having no deleterious effect within species, cause inviability or sterility when brought together with genes from another species. Here I model speciation as the accumulation of genic incompatibilities between diverging populations. Several results are obtained. First, and most important, the number of genic incompatibilities between taxa increases much faster than linearly with time. In particular, the probability of speciation increases at least as fast as the square of the time since separation between two taxa. Second, as Muller realized, all hybrid incompatibilities must initially be asymmetric. Third, at loci that have diverged between taxa, evolutionarily derived alleles cause hybrid problems far more often than ancestral alleles. Last, it is "easier" to evolve complex hybrid incompatibilities requiring the simultaneous action of three or more loci than to evolve simple incompatibilities between pairs of genes. These results have several important implications for genetic analyses of speciation.

The Independent Effects of Goal Contents and Motives on Well-Being: It’s Both What You Pursue and Why You Pursue It

Abstract: The assertion that both the content of goals and the motives behind goals affect psychological well-being has been controversial. Three studies examined this issue directly, showing that both what goals people pursue (i.e., whether they strive for extrinsic vs. intrinsic goal contents) and why people pursue them (i.e., whether they strive for autonomous vs. controlled motives) make significant independent contributions to psychological well-being. The pattern emerged in between-person and within-person studies of cross-sectional well-being and also emerged in a year-long study of prospective change in well-being. Implications for prescriptive theories of happiness are discussed.

Generation of ultrahigh peak power pulses by chirped pulse amplification

Abstract: Single picosecond pulses have been amplified to the terawatt level by a table-top-size Nd:glass amplifier by using the technique of chirped pulse amplification (CPA). The divergence of the beam is twice the diffraction limit, making the brightness of this source equal to approximately 2*10/sup +18/ W/(cm-sr), which is thought to be the highest brightness yet reported. The CPA technique allows the efficient energy extraction from extremely compact amplifier systems. Amplification of chirped pulses over nine orders of magnitude, i.e. from nanojoule to the joule level, has been demonstrated. >

Consumer information search revisited: Theory and empirical analysis

Abstract: A comprehensive theoretical framework for understanding consumers' information search behavior is presented. Unlike previous research, our model identifies not only what factors affect consumers' search behavior but also how these factors interact with each other. In particular, the model emphasizes the effect of prior brand perceptions on the search process. We argue that when consumers have brand-specific prior distributions of utility, the existence of relative uncertainty among brands is necessary for search to be useful. Thus, we explain why product class involvement or low search costs may not be sufficient to induce large amounts of search activity and why there may be an inverted-U-shaped relationship between search activity and experience. We test our theory on consumers' search behavior for new automobiles, using data collected contemporaneously with consumers' actual decision process. Our data support our theory.

Measuring Internal Political Efficacy in the 1988 National Election Study.

Abstract: Political efficacy has been studied extensively since the 1950s, hut analysts have never been fully satisfied with its measurement. After considerable testing, four new questions tapping internal political efficacy were added to the 1988 National Election Study. Our investigation shows that inter-item correlations among these questions indicate high internal consistency, that by both exploratory and confirmatory factor analysis the items measure a single concept distinct from external efficacy and political trust, that the measurement model is robust across major subgroups, and that the overall scale is externally valid and provides a good distribution of efficacy scores across the population. Further, the results of an order experiment in the survey suggest that responses are unaffected by mode of presentation. In short, the four new questions constitute the most satisfactory measure of internal political efficacy to date.