4,583 research outputs found
Program for standard statistical distributions
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
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
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
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
Determination of statistics for any rotation of axes of a bivariate normal elliptical distribution
Determination of mean, variance, covariance, and correlation estimates for axes rotation of bivariate normal elliptical distributio
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