8,710 research outputs found
A new skew-elliptical distribution and its properties
This article generalizes a multivariate skew-elliptical distribution and describes its many interesting properties. The univariate version of the new distribution is compared with two other currently used distributions. The use of the new distribution is illustrated with a real data example suitable for regression modelling. The new model provides a better model fit than its two rivals as evaluated by some suitable Bayesian model selection criteria
Detection of hidden structures on all scales in amorphous materials and complex physical systems: basic notions and applications to networks, lattice systems, and glasses
Recent decades have seen the discovery of numerous complex materials. At the
root of the complexity underlying many of these materials lies a large number
of possible contending atomic- and larger-scale configurations and the
intricate correlations between their constituents. For a detailed
understanding, there is a need for tools that enable the detection of pertinent
structures on all spatial and temporal scales. Towards this end, we suggest a
new method by invoking ideas from network analysis and information theory. Our
method efficiently identifies basic unit cells and topological defects in
systems with low disorder and may analyze general amorphous structures to
identify candidate natural structures where a clear definition of order is
lacking. This general unbiased detection of physical structure does not require
a guess as to which of the system properties should be deemed as important and
may constitute a natural point of departure for further analysis. The method
applies to both static and dynamic systems.Comment: (23 pages, 9 figures
Design and fabrication of a data logger for atmospheric pressure, temperature and relative humidity for gas-filled detector development
A novel instrument has been developed to monitor and record the ambient pa-
rameters such as temperature, atmospheric pressure and relative humidity. These
parameters are very essential for understanding the characteristics such as
gain of gas filled detectors like Gas Electron Multiplier (GEM) and Multi Wire
Propor- tional Counter (MWPC). In this article the details of the design,
fabrication and operation processes of the device has been presented.Comment: 11 pages, 12 figure
Neutrino Emissivity of Dense Stars
The neutrino emissivity of compact stars is investigated in this work. We
consider stars consisting of nuclear as well as quark matter for this purpose.
Different models are used to calculate the composition of nuclear and quark
matter and the neutrino emissivity. Depending on the model under consideration,
the neutrino emissivity of nuclear as well as quark matter varies over a wide
range. We find that for nuclear matter, the direct URCA processes are allowed
for most of the relativistic models without and with strange baryons, whereas
for the nonrelativistic models this shows a strong dependence on the type of
nuclear interaction employed. When the direct URCA processes are allowed, the
neutrino emissivity of hadronic matter is larger than that of the quark matter
by several orders of magnitude. We also find that the neutrino emissivity
departs from behavior when the temperature is larger than the difference
in the Fermi momenta of the particles, participating in the neutrino-producing
reactions.Comment: Latex file. 5 figures available on request. accepted in Int. J. Mod.
Phys.
Characterization of Jets in Relativistic Heavy Ion Collisions
Jet quenching is considered to be one of the signatures of the formation of
quark gluon plasma. In order to investigate the jet quenching, it is necessary
to detect jets produced in relativistic heavy ion collisions, determine their
properties and compare those with the jets one obtains in hadron-hadron or
collisions. In this work, we propose that calculation of flow
parameters may be used to detect and characterize jets in relativistic heavy
ion collisions.Comment: 18 pages, 4 figures, more discussions are added, to be published in
Phys. Rev.
On the Limitations of Neutrino Emissivity Formula of Iwamoto
The neutrino emissivity from two and three flavour quark matter is
numerically calculated and compared with Iwamoto's formula. We find that the
calculated emissivity is smaller than Iwamoto's result by orders of magnitude
when is comparable with the temperature. We
attribute it to the severe restriction imposed by momentum conservation on the
phase space integral. We obtain an alternate formula for the neutrino
emissivity which is valid when the quarks and electrons are degenerate and
is large compared to the temperature.Comment: Latex Version 2.09, 15 pages, 5 postscript figures available upon
request, preprint No. IP/BBSR/93-6
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