139 research outputs found
The Kolmogorov-Smirnov test for the CMB
We investigate the statistics of the cosmic microwave background using the
Kolmogorov-Smirnov test. We show that, when we correctly de-correlate the data,
the partition function of the Kolmogorov stochasticity parameter is compatible
with the Kolmogorov distribution and, contrary to previous claims, the CMB data
are compatible with Gaussian fluctuations with the correlation function given
by standard Lambda-CDM. We then use the Kolmogorov-Smirnov test to derive upper
bounds on residual point source power in the CMB, and indicate the promise of
this statistics for further datasets, especially Planck, to search for
deviations from Gaussianity and for detecting point sources and Galactic
foregrounds.Comment: Improved significance of the results (which remain unchanged) by
using patches instead of ring segments in the analysis. Added sky maps of the
Kolmogorov-parameter for original and de-correlated CMB ma
Dark energy and Josephson junctions
It has been recently claimed that dark energy can be (and has been) observed
in laboratory experiments by measuring the power spectrum of the
noise current in a resistively shunted Josephson junction and that in new
dedicated experiments, which will soon test a higher frequency range,
should show a deviation from the linear rising observed in the
lower frequency region because higher frequencies should not contribute to dark
energy. Based on previous work on theoretical aspects of the
fluctuation-dissipation theorem, we carefully investigate these issues and show
that these claims are based on a misunderstanding of the physical origin of the
spectral function . According to our analysis, dark energy has
never been (and will never be) observed in Josephson junctions experiments. We
also predict that no deviation from the linear rising behavior of
will be observed in forthcoming experiments. Our findings provide new (we
believe definite) arguments which strongly support previous criticisms.Comment: 9 pages, no figure
Dark Energy and the quietness of the Local Hubble Flow
The linearity and quietness of the Local () Hubble Flow (LHF) in
view of the very clumpy local universe is a long standing puzzle in standard
and in open CDM cosmogony. The question addressed in this paper is whether the
antigravity component of the recently discovered dark energy can cool the
velocity flow enough to provide a solution to this puzzle. We calculate the
growth of matter fluctuations in a flat universe containing a fraction
of dark energy obeying the time independent equation of state
. We find that dark energy can indeed cool the LHF. However the
dark energy parameter values required to make the predicted velocity dispersion
consistent with the observed value have been ruled out
by other observational tests constraining the dark energy parameters and
. Therefore despite the claims of recent qualitative studies dark
energy with time independent equation of state can not by itself explain the
quietness and linearity of the Local Hubble Flow.Comment: 4 pages, 3 figures, accepted in Phys. Rev. D. Minor corrections, one
figure adde
(gamma,np) reactions in <sup>12</sup>C , <sup>6</sup>Li and <sup>3,4</sup>He
The emission of neutron-proton pairs is the most probable outcome of photon absorbtion in the energy region above the giant resonance at least up to the pion threshold, but little detailed information on the process has been obtained due to experimental difficulties. Two nucleon emission following photon absorbtion by a correlated pair is favoured
compared to direct knockout of a single nucleon, which is suppressed by the large momentum mismatch between the ingoing photon and a single outgoing fast nucleon. Studies of the (gamma,np) process seek firstly to obtain a quantitative
understanding of the photon interaction mechanism, and through this to open the door to investigations of nucleon
correlations in nuclei [1], information about which is long sought but not readily obtainable
Perturbations in cosmologies with a scalar field and a perfect fluid
We study the properties of cosmological density perturbations in a
multi-component system consisting of a scalar field and a perfect fluid. We
discuss the number of degrees of freedom completely describing the system,
introduce a full set of dynamical gauge-invariant equations in terms of the
curvature and entropy perturbations, and display an efficient formulation of
these equations as a first-order system linked by a fairly sparse matrix. Our
formalism includes spatial gradients, extending previous formulations
restricted to the large-scale limit, and fully accounts for the evolution of an
isocurvature mode intrinsic to the scalar field. We then address the issue of
the adiabatic condition, in particular demonstrating its preservation on large
scales. Finally, we apply our formalism to the quintessence scenario and
clearly underline the importance of initial conditions when considering
late-time perturbations. In particular, we show that entropy perturbations can
still be present when the quintessence field energy density becomes
non-negligible.Comment: RevTex4, 9 pages, 3 figures. Significant additions on the
quintessence scenario (new appendix and additional numerical example).
Conclusions unchanged, but more robus
Quantization of the interior Schwarzschild black hole
We study a Hamiltonian quantum formalism of a spherically symmetric
space-time which can be identified with the interior of a Schwarzschild black
hole. The phase space of this model is spanned by two dynamical variables and
their conjugate momenta. It is shown that the classical Lagrangian of the model
gives rise the interior metric of a Schwarzschild black hole. We also show that
the the mass of such a system is a Dirac observable and then by quantization of
the model by Wheeler-DeWitt approach and constructing suitable wave packets we
get the mass spectrum of the black hole.Comment: 12 pages, 1 figure, revised versio
Progress in muscular dystrophy research with special emphasis on gene therapy
Duchenne muscular dystrophy (DMD) is an X-linked, progressive muscle-wasting disease caused by mutations in the DMD gene. Since the disease was described by physicians in the 19th century, information about the subject has been accumulated. One author (Sugita) was one of the coworkers who first reported that the serum creatine kinase (CK) level is elevated in progressive muscular dystrophy patients. Even 50 years after that first report, an elevated serum CK level is still the most useful marker in the diagnosis of DMD, a sensitive index of the state of skeletal muscle, and useful to evaluate therapeutic effects. In the latter half of this article, we describe recent progress in the therapy of DMD, with an emphasis on gene therapies, particularly exon skipping
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Representational predicaments for employees: Their impact on perceptions of supervisors\u27 individualized consideration and on employee job satisfaction
A representational predicament for a subordinate vis-Ć -vis his or her immediate superior involves perceptual incongruence with the superior about the subordinate\u27s work or work context, with unfavourable implications for the employee. An instrument to measure the incidence of two types of representational predicament, being neglected and negative slanting, was developed and then validated through an initial survey of 327 employees. A subsequent substantive survey with a fresh sample of 330 employees largely supported a conceptual model linking being neglected and negative slanting to perceptions of low individualized consideration by superiors and to low overall job satisfaction. The respondents in both surveys were all Hong Kong Chinese. Two case examples drawn from qualitative interviews illustrate and support the conceptual model. Based on the research findings, we recommend some practical exercises to use in training interventions with leaders and subordinates. Ā© 2013 Copyright Taylor and Francis Group, LLC
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