5,364 research outputs found

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    Radiation can never again dominate Matter in a Vacuum Dominated Universe

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    We demonstrate that in a vacuum-energy-dominated expansion phase, surprisingly neither the decay of matter nor matter-antimatter annihilation into relativistic particles can ever cause radiation to once again dominate over matter in the future history of the universe.Comment: updated version, as it will appear in Phys. Rev D. Title change, and some other minor alteration

    Cosmology in a supersymmetric model with gauged BLB-L

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    We consider salient cosmological features of a supersymmetric model which is Left-Right symmetric and therefore possessing gauged BLB-L symmetry. The requirement of breaking parity and also obtaining charge preserving vacua introduces some unique features to this model (MSLRM), resulting in a preference for non-thermal Leptogenesis. Assuming that the model preserves TeV scale supersymmetry, we show that the vacuum structure generically possesses domain walls, which can serve two important purposes. They can signal a secondary inflation required to remove unwanted relics such as gravitino and moduli and also generate lepton asymmetry by a mechanism similar to electroweak baryogenesis. The requirement of disappearance of domain walls imposes constraints on the soft parameters of the theory, testable at the TeV scale. We also propose an alternative model with spontaneous parity violation (MSLR\rlap/P). Incorporating the same cosmological considerations in this case entails constraints on a different set of soft parameters.Comment: 18 pages. Minor changes in text, but conclusion remains same. Published in Phys. Rev.

    Harold Jeffreys's Theory of Probability Revisited

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    Published exactly seventy years ago, Jeffreys's Theory of Probability (1939) has had a unique impact on the Bayesian community and is now considered to be one of the main classics in Bayesian Statistics as well as the initiator of the objective Bayes school. In particular, its advances on the derivation of noninformative priors as well as on the scaling of Bayes factors have had a lasting impact on the field. However, the book reflects the characteristics of the time, especially in terms of mathematical rigor. In this paper we point out the fundamental aspects of this reference work, especially the thorough coverage of testing problems and the construction of both estimation and testing noninformative priors based on functional divergences. Our major aim here is to help modern readers in navigating in this difficult text and in concentrating on passages that are still relevant today.Comment: This paper commented in: [arXiv:1001.2967], [arXiv:1001.2968], [arXiv:1001.2970], [arXiv:1001.2975], [arXiv:1001.2985], [arXiv:1001.3073]. Rejoinder in [arXiv:0909.1008]. Published in at http://dx.doi.org/10.1214/09-STS284 the Statistical Science (http://www.imstat.org/sts/) by the Institute of Mathematical Statistics (http://www.imstat.org

    Tests of Bayesian Model Selection Techniques for Gravitational Wave Astronomy

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    The analysis of gravitational wave data involves many model selection problems. The most important example is the detection problem of selecting between the data being consistent with instrument noise alone, or instrument noise and a gravitational wave signal. The analysis of data from ground based gravitational wave detectors is mostly conducted using classical statistics, and methods such as the Neyman-Pearson criteria are used for model selection. Future space based detectors, such as the \emph{Laser Interferometer Space Antenna} (LISA), are expected to produced rich data streams containing the signals from many millions of sources. Determining the number of sources that are resolvable, and the most appropriate description of each source poses a challenging model selection problem that may best be addressed in a Bayesian framework. An important class of LISA sources are the millions of low-mass binary systems within our own galaxy, tens of thousands of which will be detectable. Not only are the number of sources unknown, but so are the number of parameters required to model the waveforms. For example, a significant subset of the resolvable galactic binaries will exhibit orbital frequency evolution, while a smaller number will have measurable eccentricity. In the Bayesian approach to model selection one needs to compute the Bayes factor between competing models. Here we explore various methods for computing Bayes factors in the context of determining which galactic binaries have measurable frequency evolution. The methods explored include a Reverse Jump Markov Chain Monte Carlo (RJMCMC) algorithm, Savage-Dickie density ratios, the Schwarz-Bayes Information Criterion (BIC), and the Laplace approximation to the model evidence. We find good agreement between all of the approaches.Comment: 11 pages, 6 figure

    Geometric View of Measurement Errors

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    The slope of the best fit line from minimizing the sum of the squared oblique errors is the root of a polynomial of degree four. This geometric view of measurement errors is used to give insight into the performance of various slope estimators for the measurement error model including an adjusted fourth moment estimator introduced by Gillard and Iles (2005) to remove the jump discontinuity in the estimator of Copas (1972). The polynomial of degree four is associated with a minimun deviation estimator. A simulation study compares these estimators showing improvement in bias and mean squared error

    Development of European standards for evaluative reporting in forensic science : The gap between intentions and perceptions

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    Criminal justice authorities of EU countries currently engage in dialogue and action to build a common area of justice and to help increase the mutual trust in judicial systems across Europe. This includes, for example, the strengthening of procedural safeguards for citizens in criminal proceedings by promoting principles such as equality of arms. Improving the smooth functioning of judicial processes is also pursued by works of expert working groups in the field of forensic science, such as the working parties under the auspices of the European Network of Forensic Science Institutes (ENFSI). This network aims to share knowledge, exchange experiences and come to mutual agreements in matters concerning forensic science practice, among them the interpretation of results of forensic examinations. For example, through its Monopoly Programmes (financially supported by the European Commission), ENFSI has funded a series of projects that come under the general theme ‘Strengthening the Evaluation of Forensic Results across Europe’. Although these initiatives reflect a strong commitment to mutual understanding on general principles of forensic interpretation, the development of standards for evaluation and reporting, including roadmaps for implementation within the ENFSI community, are fraught with conceptual and practical hurdles. In particular, experience through consultations with forensic science practitioners shows that there is a considerable gap between the intentions of a harmonised view on principles of forensic interpretation and the way in which works towards such common understanding are perceived in the community. In this paper, we will review and discuss several recurrently raised concerns. We acknowledge practical constraints such as limited resources for training and education, but we shall also argue that addressing topics in forensic interpretation now is of vital importance because forensic science continues to be challenged by proactive participants in the legal process that tend to become more demanding and less forgiving

    Pilot study : can inspiratory muscle training relieve symptoms ff dyspnoea and improve quality of life for advanced cancer patients ?: 1872 Board #24 June 2, 3: 30 PM - 5: 00 PM.

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    Dyspnoea is a common symptom of advanced cancer patients, and impacts upon physical, social and psychological wellbeing. Currently opioids are recommended for those suffering with chronic dyspnoea, despite an association with longer term health issues. Inspiratory muscle training (IMT) promotes chronic adaptations within the inspiratory musculature and has consistently been shown to reduce dyspnoea and improve lung mechanics, functional exercise capacity and quality of life in a variety of clinical populations, however this has yet to be tested in patients with cancer.N/
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