Bayesian Analysis of Inflation II: Model Selection and Constraints on Reheating

We discuss the model selection problem for inflationary cosmology. We couple ModeCode, a publicly-available numerical solver for the primordial perturbation spectra, to the nested sampler MultiNest, in order to efficiently compute Bayesian evidence. Particular attention is paid to the specification of physically realistic priors, including the parametrization of the post-inflationary expansion and associated thermalization scale. It is confirmed that while present-day data tightly constrains the properties of the power spectrum, it cannot usefully distinguish between the members of a large class of simple inflationary models. We also compute evidence using a simulated Planck likelihood, showing that while Planck will have more power than WMAP to discriminate between inflationary models, it will not definitively address the inflationary model selection problem on its own. However, Planck will place very tight constraints on any model with more than one observationally-distinct inflationary regime -- e.g. the large- and small-field limits of the hilltop inflation model -- and put useful limits on different reheating scenarios for a given model.Comment: ModeCode package available from http://zuserver2.star.ucl.ac.uk/~hiranya/ModeCode/ModeCode (requires CosmoMC and MultiNest); to be published in PRD. Typos fixe

Thermal Activation Rates in the Chirally Asymmetric Gross-Neveu Model

We address the problem of how to incorporate quantum effects into the calculation of finite-temperature decay rates for a metastable state of a quantum field theory. To do this, we consider the Gross-Neveu model with an explicit chiral symmetry breaking term, which allows for a metastable state. This theory can be shown to have a "critical bubble" which is a solution to the *exact* equations of motions (i.e. to all orders in perturbation theory, including all higher derivative, quantum and thermal corrections). This configuration mediates the thermal activation of the metastable vacuum to the true ground state, with a decay rate $\Gamma \propto \exp(-F_c/T)$, where $F_c$ is the free energy of the critical bubble. We then compare this exact calculation to various approximations that have been used in previous work. We find that these approximations all *overestimate* the activation rate. Furthermore, we study the effect of finite baryon number upon the bubble profile and the activation barriers. We find that beyond a critical baryon number the activation barriers disappear altogether.Comment: 20 pages, LaTeX, 9 figures using epsf.tex. Now auto-generates P

Solid feed provision reduces fecal clostridial excretion in veal calves

Enterotoxemia is characterized by a highly fatal hemorrhagic enteritis in cattle, caused by Clostridium perfringens. Production systems with intensive feeding, such as the veal industry, are predisposed. The primary objective of this study was to determine the effect of solid feed provision on fecal C. perfringens excretion in veal calves. Ten Holstein Friesian bull veal calves were randomly assigned to one of two test diets. Group I received solemnly milk replacer twice daily, while group 2 received milk replacer and a maximum of 300g solid feed/day, consisting of a mixture of 30% barley, 30% corn, 30% hulled wheat and 10% chopped straw. The number of C. perfringens per g feces or fecal clostridia! counts (FCC) were determined for all calves. Mean FCC were significantly lower in the calves fed milk replacer and solid feed, than in the calves fed solemnly milk replacer. Although the correlation between FCC and enterotoxemia risk remains to be determined, the provision of solid feed to veal calves reduced clostridial excretion, which might contribute to the prevention of this disease

Universes inside a Λ\Lambda black hole

We address the question of universes inside a $\Lambda$ black hole which is described by a spherically symmetric globally regular solution to the Einstein equations with a variable cosmological term $\Lambda_{\mu\nu}$, asymptotically $\Lambda g_{\mu\nu}$ as $r\to 0$ with $\Lambda$ of the scale of symmetry restoration. Global structure of spacetime contains an infinite sequence of black and white holes, vacuum regular cores and asymptotically flat universes. Regular core of a $\Lambda$ white hole models the initial stages of the Universe evolution. In this model it starts from a nonsingular nonsimultaneous big bang, which is followed by a Kasner-type anisotropic expansion. Creation of a mass occurs mostly at the anisotropic stage of quick decay of the initial vacuum energy. We estimate also the probability of quantum birth of baby universes inside a $\Lambda$ black hole due to quantum instability of the de Sitter vacuum.Comment: REVTEX, 9 pages, 13 figures. To appear in Physics Letters

Relationship of Self-Rated Health to Stroke Incidence and Mortality in Older Individuals with and without a History of Stroke: A Longitudinal Study of the MRC Cognitive Function and Ageing (CFAS) Population.

INTRODUCTION: Poor self-rated health (SRH) has been associated with increased risk of death and poor health outcomes even after adjusting for confounders. However its' relationship with disease-specific mortality and morbidity has been less studied. SRH may also be particularly predictive of health outcomes in those with pre-existing conditions. We studied whether SRH predicts new stroke in older people who have never had a stroke, or a recurrence in those with a prior history of stroke. METHODS: MRC CFAS I is a multicentre cohort study of a population representative sample of people in their 65th year and older. A comprehensive interview at baseline included questions about presence of stroke, self-rated health and functional disability. Follow-up at 2 years included self-report of stroke and stroke death obtained from death certificates. Multiple logistical regression determined odds of stroke at 2 years adjusting for confounders including disability and health behaviours. Survival analysis was performed until June 2014 with follow-up for up to 13 years. RESULTS: 11,957 participants were included, of whom 11,181 (93.8%) had no history of stroke and 776 (6.2%) one or more previous strokes. Fewer with no history of stroke reported poor SRH than those with stroke (5 versus 21%). In those with no history of stroke, poor self-rated health predicted stroke incidence (OR 1.5 (1.1-1.9)), but not stroke mortality (OR 1.2 (0.8-1.9)) at 2 years nor for up to 13 years (OR 1.2(0.9-1.7)). In those with a history of stroke, self-rated health did not predict stroke incidence (OR 0.9(0.6-1.4)), stroke mortality (OR 1.1(0.5-2.5)), or survival (OR 1.1(0.6-2.1)). CONCLUSIONS: Poor self-rated health predicts risk of stroke at 2 years but not stroke mortality among the older population without a previous history of stroke. SRH may be helpful in predicting who may be at risk of developing a stroke in the near future.We thank the MRC CFAS I study group for data collection and management. We are also grateful to all respondents, their families and their primary care teams from across the country for their participation in the CFAS.This is the final version of the article. It first appeared from the Public Library of Science via http://dx.doi.org/10.1371/journal.pone.015017

Cosmic structure formation in Hybrid Inflation models

A wide class of inflationary models, known as Hybrid Inflation models, may produce topological defects during a phase transition at the end of the inflationary epoch. We point out that, if the energy scale of these defects is close to that of Grand Unification, then their effect on cosmic structure formation and the generation of microwave background anisotropies cannot be ignored. Therefore, it is possible for structure to be seeded by a combination of the adiabatic perturbations produced during inflation and active isocurvature perturbations produced by defects. Since the two mechanisms are uncorrelated the power spectra can be computed by a weighted average of the individual contributions. We investigate the possible observational consequences of this with reference to general Hybrid Inflation models and also a specific model based on Supergravity. These mixed perturbation scenarios have some novel observational consequences and these are discussed qualitatively.Comment: 22 Page

Gastro-intestinale Clostridium perfringens-infecties : een blijvend gevaar in de Belgische rundveehouderij

peer reviewe

Genetic variation in the carbonic anhydrase isozymes of macaque monkeys : III. Biosynthesis of carbonic anhydrases in bone marrow erythroid cells and peripheral blood reticulocytes of Macaco nemestrina

The carbonic anhydrase isozymes (CA I and CA II) of the pig-tailed macaque, Macaca nemestrina, have been chosen to study the regulation of enzyme levels in red blood cells. Two quantitative variants of CA I that are ideal for studies of enzyme regulation exist in this species. One variant is one of four known electrophoretic types of CA I, designated CA Ia, which is present at levels about 30% of those of the other electrophoretic types. The other is a deficiency variant of CA I which, in homozygotes, reduces the product of the CA I locus about 5000-fold and reduces the product of the CA II locus by about 60%. -[14C]Serine was used to study the biosynthesis of CA I and CA II isozymes in the reticulocytes of animals carrying these CA I variants. Specific radioactivity and total incorporation data from bone marrow erythroid cells, and peripheral blood reticulocytes indicate that the reduced CA Ia concentration is probably the result of degradation. This degradation appears to occur for only a short time before the reticulocytes enter the peripheral blood. It was not possible to determine whether the 5000-fold reduction of CA I in the CA I-deficient animals is due to reduced transcription, reduced translation, or degradation. The effect of the CA I-deficiency mutation on the synthesis of CA II was also studied. For each dose of CA I-deficiency gene, there appears to be a 30% reduction in the rate of -[14C]serine incorporation into CA II, thereby accounting for the reduced CA II concentration in CA I-deficient animals.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/33820/1/0000077.pd