608,313 research outputs found
Equivalence principle in the new general relativity
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 , and satisfy the condition, . In the two special cases where either or
is vanishing, however, this equality is not satisfied for the
solutions when some components of the parallel vector fields tend to zero as
for large .Comment: 18 pages, LaTeX, published in Prog. Theor. Phys. 96 No.5 (1996
Temperature effect on space charge dynamics in XLPE insulation
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
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
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 and Extraction of from Semileptonic Decays
By globally analyzing all existing measured branching fractions and partial
rates in different four momentum transfer-squared bins of decays, we obtain the product of the form factor and magnitude of
CKM matrix element to be . With this
product, we determine the semileptonic form factor
in conjunction with the value of
determined from the SM global fit. Alternately, with the product together with
the input of the form factor calculated in lattice QCD recently, we
extract , where the error is
still dominated by the uncertainty of the form factor calculated in lattice
QCD. Combining the
extracted from all existing measurements of decays and
together, we find the most
precisely determined to be , which improves
the accuracy of the PDG'2014 value by
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