26,895 research outputs found
Extensions in FormCalc 5.3
We present a new tool for editing Feynman diagrams as well as several
extensions in version 5.3 of the package FormCalc for the calculation of
Feynman diagrams.Comment: 8 pages, contribution to the proceedings of the ACAT workshop,
Amsterdam, April 23-27, 200
Quantitative analysis of the relation between entropy and nucleosynthesis in central Ca + Ca and Nb + Nb collisions
The final states of central Ca + Ca and Nb + Nb collisions at 400 and 1050 MeV/nucleon and at 400 and 650 MeV/nucleon, respectively, are studied with two independently developed statistical models, namely the classical microcanonical model and the quantum-statistical grand canonical model. It is shown that these models are in agreement with each other for these systems. Furthermore, it is demonstrated that there is essentially a one-to-one relationship between the observed relative abundances of the light fragments p, d, t, 3He, and α and the entropy per nucleon, for breakup temperatures greater than 30 MeV. Entropy values of 3.5–4 are deduced from high-multiplicity selected fragment yield data
An arithmetic Hilbert-Samuel theorem for singular hermitian line bundles and cusp forms
We prove an arithmetic Hilbert-Samuel type theorem for semi-positive singular
hermitian line bundles of finite height. In particular, the theorem applies to
the log-singular metrics of Burgos-Kramer-K\"uhn. Our theorem is thus suitable
for application to some non-compact Shimura varieties with their bundles of
cusp forms. As an application, we treat the case of Hilbert modular surfaces,
establishing an arithmetic analogue of the classical result expressing the
dimensions of spaces of cusp forms in terms of special values of Dedekind zeta
functions
Interplay between Hbs and bsgamma in the MSSM with Non-Minimal Flavour Violation
We investigate the constraints on flavour-changing neutral heavy Higgs-boson
decays H-> b \bar s from b -> s gamma bounds on the flavour-mixing parameters
of the MSSM with non-minimal flavour violation (NMFV). In our analysis we
include the contributions from the SM and new physics due to general flavour
mixing in the squark mass matrices. We study the case of one and two non-zero
flavour-mixing parameters and find that in the latter case the interference can
raise the Higgs flavour-changing branching ratios by one or two orders of
magnitude with respect to previous predictions based on a single non-zero
parameter and in agreement with present constraints from physics. In the
course of our work we developed a new "FeynArts" model file for the NMFV MSSM
and added the necessary code for the evaluation to "FormCalc". Both extensions
are publicly available.Comment: LaTeX2e, 15 pages, 4 figures. Computation improved and figures
replaced accordingly. Some references added. Main conclusions remain
untouche
Angular distributions of γ rays from the 7Li(p,γ) reaction at low energies
Angular distributions of the 14–17 MeV γ rays from the 7Li(p,γ) reaction at Ep=450, 402, and 80 keV were measured at 0°≤θlab≤135°, using a BGO detector and a 28-μg/cm2 LiF target. The angular distributions at Ep=450 and 402 keV agree with the previous results by Mainsbridge; at Ep=80 keV the ground-state transition is anisotropic on the order of 20%, confirming recent results by Chasteler et al
Women’s facial attractiveness is related to their body mass index, but not their salivary cortisol
Objectives: Although many theories of human facial attractiveness propose positive correlations between facial attractiveness and measures of actual health, evidence for such correlations is somewhat mixed. Here we sought to replicate a recent study reporting that women’s facial attractiveness is independently related to both their adiposity and cortisol.
Methods: Ninety-six women provided saliva samples, which were analyzed for cortisol level, and their height and weight, which were used to calculate their body mass index (BMI). A digital face image of each woman was also taken under standardized photographic conditions and rated for attractiveness.
Results: There was a significant negative correlation between women’s facial attractiveness and BMI. By contrast, salivary cortisol and facial attractiveness were not significantly correlated.
Conclusions: Our results suggest that the types of health information reflected in women's faces include qualities that are indexed by BMI, but do not necessarily include qualities that are indexed by cortisol
Does the interaction between cortisol and testosterone predict men's facial attractiveness?
Although some researchers have suggested that the interaction between cortisol and testosterone predicts ratings of men’s facial attractiveness, evidence for this pattern of results is equivocal. Consequently, the current study tested for a correlation between men’s facial attractiveness and the interaction between their cortisol and testosterone levels. We also tested for corresponding relationships between the interaction between cortisol and testosterone and ratings of men’s facial health and dominance (perceived traits that are correlated with facial attractiveness in men). We found no evidence that ratings of either facial attractiveness or health were correlated with the interaction between cortisol and testosterone. Some analyses suggested that the interaction between cortisol and testosterone levels may predict ratings of men’s facial dominance, however, with testosterone being more closely related to facial dominance ratings among men with higher cortisol. Our results suggest that the relationship between men’s facial attractiveness and the interaction between cortisol and testosterone is not robust
Sex ratio influences the motivational salience of facial attractiveness
The sex ratio of the local population influences mating-related behaviours in many species. Recent experiments show that male-biased sex ratios increase the amount of financial resources men will invest in potential mates, suggesting that sex ratios influence allocation of mating effort in humans. To investigate this issue further, we tested for effects of cues to the sex ratio of the local population on the motivational salience of attractiveness in own-sex and opposite-sex faces. We did this using an effort-based key-press task, in which the motivational salience of facial attractiveness was assessed in samples of faces in which the ratio of male to female images was manipulated. The motivational salience of attractive opposite-sex, but not own-sex, faces was greater in the own-sex-biased (high competition for mates) than in the opposite-sex-biased (low competition for mates) condition. Moreover, this effect was not modulated by participant sex. These results present new evidence that sex ratio influences human mating-related behaviours. They also present the first evidence that the perceived sex ratio of the local population may modulate allocation of mating effort in women, as well as men
Assessing the Quality of Regulatory Impact Analyses
This study provides the most comprehensive evaluation of the quality of recent economic analyses that agencies conduct before finalizing major regulations. We construct a new dataset that includes analyses of forty-eight major health, safety, and environmental regulations from mid-1996 to mid-1999. This dataset provides detailed information on a variety of issues, including an agency's treatment of benefits, costs, net benefits, discounting, and uncertainty. We use this dataset to assess the quality of recent economic analyses and to determine the extent to which they are consistent with President Clinton's Executive Order 12866 and the benefit-cost guidelines issued by the Office of Management and Budget (OMB). We find that economic analyses prepared by regulatory agencies typically do not provide enough information to make decisions that will maximize the efficiency or effectiveness of a rule. Agencies quantified net benefits for only 29 percent of the rules. Agencies failed to discuss alternatives in 27 percent of the rules and quantified costs and benefits of alternatives in only 31 percent of the rules. Our findings strongly suggest that agencies generally failed to comply with the executive order and adhere to the OMB guidelines. We offer specific suggestions for improving the quality of analysis and the transparency of the regulatory process, including writing clear executive summaries, making analyses available on the Internet, providing more careful consideration of alternatives to a regulation, and estimating net benefits of a regulation when data on costs and benefits are provided.
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