608,313 research outputs found

    Equivalence principle in the new general relativity

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    We study the problem of whether the active gravitational mass of an isolated system is equal to the total energy in the tetrad theory of gravitation. The superpotential is derived using the gravitational Lagrangian which is invariant under parity operation, and applied to an exact spherically symmetric solution. Its associated energy is found equal to the gravitational mass. The field equation in vacuum is also solved at far distances under the assumption of spherical symmetry. Using the most general expression for parallel vector fields with spherical symmetry, we find that the equality between the gravitational mass and the energy is always true if the parameters of the theory a1a_1, a2a_2 and a3a_3 satisfy the condition, (a1+a2)(a1−4a3/9)≠0(a_1+ a_2) (a_1-4a_3/9)\neq0. In the two special cases where either (a1+a2)(a_1+a_2) or (a1−4a3/9)(a_1-4a_3/9) is vanishing, however, this equality is not satisfied for the solutions when some components of the parallel vector fields tend to zero as 1/r1/\sqrt{r} for large rr.Comment: 18 pages, LaTeX, published in Prog. Theor. Phys. 96 No.5 (1996

    Temperature effect on space charge dynamics in XLPE insulation

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    This paper reports on space charge evolution in crosslinked polyethylene (XLPE) planar samples approximately 1.20 mm thick subjected to electric stress level of 30 kVdc/mm under four temperature 25 oC, 50 oC, 70 oC and 90 oC for 24 hours. Space charge profiles in both as-received and degassed samples were measured using the laser induced pressure pulse (LIPP) technique. The dc threshold stresses at which space charge initiates are greatly affected by testing temperatures. The results suggest that testing temperature has numerous effects on space charge dynamics such as enhancement of ionic dissociation of polar crosslinked by-products, charge injection, charge mobility and electrical conductivity. Space charge distributions of very different nature were seen at lower temperatures when comparing the results of as-received samples with degassed samples. However at higher temperature, the space charge distribution took the same form, although of lower concentration in degassed samples. Space charge distributions are dominated by positive charge when tested at high temperatures regardless of sample treatment and positive charge propagation enhances as testing temperature increases. This can be a major cause of concern as positive charge propagation has been reported to be related to insulation breakdown

    The looping probability of random heteropolymers helps to understand the scaling properties of biopolymers

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    Random heteropolymers are a minimal description of biopolymers and can provide a theoretical framework to the investigate the formation of loops in biophysical experiments. A two--state model provides a consistent and robust way to study the scaling properties of loop formation in polymers of the size of typical biological systems. Combining it with self--adjusting simulated--tempering simulations, we can calculate numerically the looping properties of several realizations of the random interactions within the chain. Differently from homopolymers, random heteropolymers display at different temperatures a continuous set of scaling exponents. The necessity of using self--averaging quantities makes finite--size effects dominant at low temperatures even for long polymers, shadowing the length--independent character of looping probability expected in analogy with homopolymeric globules. This could provide a simple explanation for the small scaling exponents found in experiments, for example in chromosome folding

    False discovery rate: setting the probability of false claim of detection

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    When testing multiple hypothesis in a survey --e.g. many different source locations, template waveforms, and so on-- the final result consists in a set of confidence intervals, each one at a desired confidence level. But the probability that at least one of these intervals does not cover the true value increases with the number of trials. With a sufficiently large array of confidence intervals, one can be sure that at least one is missing the true value. In particular, the probability of false claim of detection becomes not negligible. In order to compensate for this, one should increase the confidence level, at the price of a reduced detection power. False discovery rate control is a relatively new statistical procedure that bounds the number of mistakes made when performing multiple hypothesis tests. We shall review this method, discussing exercise applications to the field of gravitational wave surveys.Comment: 7 pages, 3 table, 3 figures. Prepared for the Proceedings of GWDAW 9 (http://lappc-in39.in2p3.fr/GWDAW9) A new section was added with a numerical example, along with two tables and a figure related to the new section. Many smaller revisions to improve readibilit

    Determination of f+K(0)f_+^K(0) and Extraction of ∣Vcs∣|V_{cs}| from Semileptonic DD Decays

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    By globally analyzing all existing measured branching fractions and partial rates in different four momentum transfer-squared q2q^2 bins of D→Ke+νeD\to Ke^+\nu_e decays, we obtain the product of the form factor and magnitude of CKM matrix element VcsV_{cs} to be f+K(0)∣Vcs∣=0.717±0.004f_+^K(0)|V_{cs}|=0.717\pm0.004. With this product, we determine the D→KD\to K semileptonic form factor f+K(0)=0.737±0.004±0.000f_+^K(0)=0.737\pm0.004\pm0.000 in conjunction with the value of ∣Vcs∣|V_{cs}| determined from the SM global fit. Alternately, with the product together with the input of the form factor f+K(0)f_+^K(0) calculated in lattice QCD recently, we extract ∣Vcs∣D→Ke+νe=0.962±0.005±0.014|V_{cs}|^{D\to Ke^+\nu_e}=0.962\pm0.005\pm0.014, where the error is still dominated by the uncertainty of the form factor calculated in lattice QCD. Combining the ∣Vcs∣Ds+→ℓ+νℓ=1.012±0.015±0.009|V_{cs}|^{D_s^+\to\ell^+\nu_\ell}=1.012\pm0.015\pm0.009 extracted from all existing measurements of Ds+→ℓ+νℓD^+_s\to\ell^+\nu_\ell decays and ∣Vcs∣D→Ke+νe=0.962±0.005±0.014|V_{cs}|^{D\to Ke^+\nu_e}=0.962\pm0.005\pm0.014 together, we find the most precisely determined ∣Vcs∣|V_{cs}| to be ∣Vcs∣=0.983±0.011|V_{cs}|=0.983\pm0.011, which improves the accuracy of the PDG'2014 value ∣Vcs∣PDG′2014=0.986±0.016|V_{cs}|^{\rm PDG'2014}=0.986\pm0.016 by 45%45\%
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