4,227 research outputs found

    Program for standard statistical distributions

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    Development of procedure to describe frequency distributions involved in statistical theory is discussed. Representation of frequency distributions by first order differential equation is presented. Classification of various types of distributions based on Pearson parameters is analyzed

    Frame (In)equivalence in Quantum Field Theory and Cosmology

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    We revisit the question of frame equivalence in Quantum Field Theory in the presence of gravity, a situation of relevance for theories aiming to describe the early Universe dynamics and Inflation in particular. We show that in those cases, the path integral measure must be carefully defined and that the requirement of diffeomorphism invariance forces it to depend non-trivially on the fields. As a consequence, the measure will transform also non-trivially between different frames and it will induce a new finite contribution to the Quantum Effective Action that we name frame discriminant. This new contribution must be taken into account in order to asses the dynamics and physical consequences of a given theory. We apply our result to scalar-tensor theories described in the Einstein and Jordan frame, where we find that the frame discriminant can be thought as inducing a scale-invariant regularization scheme in the Jordan frame.Comment: 33 pages, minor correction

    Role of p38 MAPK inhibitor in conditioned fear

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    p38 mitogen activated protein kinase (p38) is a kinase that has been implicated in cellular plasticity, stress, and psychiatric disorders and recently in the process of DNA repair. Recently, we have shown that p38 is responsible for inhibiting Glycogen Synthase Kinase 3β (GSK3β), which has also been shown to be involved in the same processes and recently in the process of DNA repair. We have also shown that GSK3β is regulated by stress and that its inhibition produces exaggerated conditioned fear. The goal of this study is to examine whether inhibiting p38 will result in a similar exaggeration of conditioned fear. To this end, mice were injected systemically with the potent and selective inhibitor of p38, SB203580 or vehicle prior to tone and foots­hock fear conditioning and tested for freezing to the tone one day later. Mice injected with SB203580 showed greater tone freezing than mice injected with vehicle. In contrast to tone freezing, SB203580 injections did not affect freezing to the context. Injections of SB203580 prior to 24 hours after fear conditioning, but before fear testing, also did not affect freezing. These data suggest that p38 plays a role in regulating the strength of conditioned fear. The fact that p38 regulates GSK3β and that inhibition of GSK3β also produces exaggerated conditioned fear raises the possibility that a p38 to GSK3β pathway may be regulating the strength of conditioned fear

    Black holes and asymptotically safe gravity

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    Quantum gravitational corrections to black holes are studied in four and higher dimensions using a renormalisation group improvement of the metric. The quantum effects are worked out in detail for asymptotically safe gravity, where the short distance physics is characterized by a non-trivial fixed point of the gravitational coupling. We find that a weakening of gravity implies a decrease of the event horizon, and the existence of a Planck-size black hole remnant with vanishing temperature and vanishing heat capacity. The absence of curvature singularities is generic and discussed together with the conformal structure and the Penrose diagram of asymptotically safe black holes. The production cross section of mini-black holes in energetic particle collisions, such as those at the Large Hadron Collider, is analysed within low-scale quantum gravity models. Quantum gravity corrections imply that cross sections display a threshold, are suppressed in the Planckian, and reproduce the semi-classical result in the deep trans-Planckian region. Further implications are discussed.Comment: 22 pages, 9 figures, Sec V G added to match published versio
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