10,090 research outputs found
Correlations in the properties of static and rapidly rotating compact stars
Correlations in the properties of the static compact stars (CSs) and the ones
rotating with the highest observed frequency of 1122Hz are studied using a
large set of equations of state (EOSs). These EOSs span various approaches and
their chemical composition vary from the nucleons to hyperons and quarks in
-equilibrium. It is found that the properties of static CS, like, the
maximum gravitational mass and radius corresponding to t he canonical mass and supramassive or
non-supramassive nature of the CS rotating at 1122 Hz are strongly correlated.
In particular, only those EOSs yield the CS rotating at 1122Hz to be
non-supramassive for which \left (\frac{M_{\rm max}^{\rm stat}}{M_\odot}\right
)^{1/2} \left (\frac{10{\rm km}}{R_{1.4}^{\rm stat}})^{3/2} is greater than
unity. Suitable parametric form which can be used to split the plane into the regions of different
supramassive nature of the CS rotating at 1122Hz is presented. Currently
measured maximum gravitational mass 1.76 of PSR J0437-4715 suggests
that the CS rotating at 1122Hz can be non-supramassive provided km.Comment: 13 pages, 4 figures, Appearing in Phys. Rev.
Non-rotating and rotating neutron stars in the extended field theoretical model
We study the properties of non-rotating and rotating neutron stars for a new
set of equations of state (EOSs) with different high density behaviour obtained
using the extended field theoretical model. The high density behaviour for
these EOSs are varied by varying the meson self-coupling and
hyperon-meson couplings in such a way that the quality of fit to the bulk
nuclear observables, nuclear matter incompressibility coefficient and
hyperon-nucleon potential depths remain practically unaffected. We find that
the largest value for maximum mass for the non-rotating neutron star is
. The radius for the neutron star with canonical mass is km provided only those EOSs are considered for which maximum mass is
larger than as it is the lower bound on the maximum mass measured
so far. Our results for the very recently discovered fastest rotating neutron
star indicate that this star is supra massive with mass and
circumferential equatorial radius km.Comment: 28 pages, 12 figures. Phys. Rev. C (in press
Temperature induced shell effects in deformed nuclei
The thermal evolution of the shell correction energy is investigated for
deformed nuclei using Strutinsky prescription in a self-consistent relativistic
mean-field framework. For temperature independent single-particle states
corresponding to either spherical or deformed nuclear shapes, the shell
correction energy steadily washes out with temperature. However,
for states pertaining to the self-consistent thermally evolving shapes of
deformed nuclei, the dual role played by the single-particle occupancies in
diluting the fluctuation effects from the single-particle spectra and in
driving the system towards a smaller deformation is crucial in determining
at moderate temperatures. In rare earth nuclei, it is found that
builds up strongly around the shape transition temperature; for
lighter deformed nuclei like and , this is relatively less
prominent.Comment: 6 pages revtex file + 4 ps files for figures, Phys. Rev. C (in press
Bright gap solitons of atoms with repulsive interaction
We report on the first experimental observation of bright matter-wave
solitons for 87Rb atoms with repulsive atom-atom interaction. This counter
intuitive situation arises inside a weak periodic potential, where anomalous
dispersion can be realized at the Brillouin zone boundary. If the coherent
atomic wavepacket is prepared at the corresponding band edge a bright soliton
is formed inside the gap. The strength of our system is the precise control of
preparation and real time manipulation, allowing the systematic investigation
of gap solitons.Comment: 4 pages, 4 figure
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Determination of the Aspect-ratio Distribution of Gold Nanorods in a Colloidal Solution using UV-visible absorption spectroscopy
Knowledge of the distribution of the aspect ratios (ARs) in a chemically-synthesized colloidal solution of Gold Nano Rods (GNRs) is an important measure in determining the quality of synthesis, and consequently the performance of the GNRs generated for various applications. In this work, an algorithm has been developed based on the Bellman Principle of Optimality to readily determine the AR distribution of synthesized GNRs in colloidal solutions. This is achieved by theoretically fitting the longitudinal plasmon resonance of GNRs obtained by UV-visible spectroscopy. The AR distribution obtained from the use of the algorithm developed have shown good agreement with those theoretically generated one as well as with the previously reported results. After bench-marking, the algorithm has been applied to determine the mean and standard deviation of the AR distribution of two GNRs solutions synthesized and examined in this work. The comparison with experimentally derived results from the use of expensive Transmission Electron Microscopic images and Dynamic Light Scattering technique shows that the algorithm developed offers a fast and thus potentially cost-effective solution to determine the quality of the synthesized GNRs specifically needed for many potential applications for the advanced sensor systems
One pion events by atmospheric neutrinos: A three flavor analysis
We study the one-pion events produced via neutral current (NC) and charged
current (CC) interactions by the atmospheric neutrinos. We analyze the ratios
of these events in the framework of oscillations between three neutrino
flavors. The ratios of the CC events induced by to that of the NC
events and a similar ratio defined with help us in distinguishing the
different regions of the neutrino parameter space.Comment: 14 pages, 4 figures (separate postscript files
Digital Availability of Product Information for Collaborative Engineering of Spacecraft
In this paper, we introduce a system to collect product information from
manufacturers and make it available in tools that are used for concurrent
design of spacecraft. The planning of a spacecraft needs experts from different
disciplines, like propulsion, power, and thermal. Since these different
disciplines rely on each other there is a high need for communication between
them, which is often realized by a Model-Based Systems Engineering (MBSE)
process and corresponding tools. We show by comparison that the product
information provided by manufacturers often does not match the information
needed by MBSE tools on a syntactic or semantic level. The information from
manufacturers is also currently not available in machine-readable formats.
Afterwards, we present a prototype of a system that makes product information
from manufacturers directly available in MBSE tools, in a machine-readable way.Comment: accepted at CDVE201
Controlling pulse propagation in optical fibers through nonlinearity and dispersion management
In case of the nonlinear Schr\"odinger equation with designed group velocity
dispersion, variable nonlinearity and gain/loss; we analytically demonstrate
the phenomenon of chirp reversal crucial for pulse reproduction. Two different
scenarios are exhibited, where the pulses experience identical dispersion
profiles, but show entirely different propagation behavior. Exact expressions
for dynamical quasi-solitons and soliton bound-states relevant for fiber
communication are also exhibited.Comment: 4 pages, 5 eps figure
Sinusoidal Excitations in Two Component Bose-Einstein Condensates
The non-linear coupled Gross-Pitaevskii equation governing the dynamics of
the two component Bose-Einstein condensate (TBEC) is shown to admit pure
sinusoidal, propagating wave solutions in quasi one dimensional geometry. These
solutions, which exist for a wide parameter range, are then investigated in the
presence of a harmonic oscillator trap with time dependent scattering length.
This illustrates the procedure for coherent control of these modes through
temporal modulation of the parameters, like scattering length and oscillator
frequency. We subsequently analyzed this system in an optical lattice, where
the occurrence of an irreversible phase transition from superfluid to insulator
phase is seen.Comment: 6 pages, 1 figur
A numerical and symbolical approximation of the Nonlinear Anderson Model
A modified perturbation theory in the strength of the nonlinear term is used
to solve the Nonlinear Schroedinger Equation with a random potential. It is
demonstrated that in some cases it is more efficient than other methods.
Moreover we obtain error estimates. This approach can be useful for the
solution of other nonlinear differential equations of physical relevance.Comment: 21 pages and 7 figure
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