64,760 research outputs found
VISHNU hybrid model for viscous QCD matter at RHIC and LHC energies
In this proceeding, we briefly describe the viscous hydrodynamics + hadron
cascade hybrid model VISHNU for relativistic heavy ion collisions and report
the current status on extracting the QGP viscosity from elliptic flow data.Comment: 4 pages, 1 figure, the proceedings of 7th International Workshop on
Critical Point and Onset of Deconfinement, Wuhan, China, Nov. 7-11, 201
Critical curvature of large- nonlinear sigma model on
We study the nonlinear sigma model on with the gravitational
coupling term, by evaluating the effective potential in the large- limit. It
is shown that there is a critical curvature of for any positive
gravitational coupling constant , and the dynamical mass generation takes
place only when . The critical curvature is analytically found as a
function of , which leads us to define a function looking like a
natural generalization of Euler-Mascheroni constant.Comment: 7 pages, LaTe
Removal of mercury (II) from aqueous solution by using rice residues
Sorption potential of rice residues for Hg(II) removal from aqueous solution was investigated. Rice husk (RH) and rice straw (RS) were selected and treated with sodium hydroxide (NaOH). The raw and modified adsorbents were characterized by Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR) and BET surface area measurements. The effects of pH, initial ion concentration, and agitation time on the removal process were studied in batch adsorption experiments. Two simple kinetic models, which are pseudo-first-order and pseudo-second-order, were tested to investigate the adsorption mechanisms. The kinetic data fits to pseudo second order model with correlation coefficients greater than 0.99 for all adsorbents. The equilibrium data fitted well with the Langmuir compared to Freundlich isotherm models. Alkali-treated adsorbent obtained larger surface area and RH-NaOH showed highest adsorption capacity followed by RS-Pure > RH-Pure > RS-NaOH. The maximum removal efficiency obtained by RH-NaOH and RS-Pure was 42 mg/l (80%) at pH 6.5 and with 2 days contact time (for 50 mg/l initial concentration and 25 mg adsorbents)
Mobility Increases the Data Offloading Ratio in D2D Caching Networks
Caching at mobile devices, accompanied by device-to-device (D2D)
communications, is one promising technique to accommodate the exponentially
increasing mobile data traffic. While most previous works ignored user
mobility, there are some recent works taking it into account. However, the
duration of user contact times has been ignored, making it difficult to
explicitly characterize the effect of mobility. In this paper, we adopt the
alternating renewal process to model the duration of both the contact and
inter-contact times, and investigate how the caching performance is affected by
mobility. The data offloading ratio, i.e., the proportion of requested data
that can be delivered via D2D links, is taken as the performance metric. We
first approximate the distribution of the communication time for a given user
by beta distribution through moment matching. With this approximation, an
accurate expression of the data offloading ratio is derived. For the
homogeneous case where the average contact and inter-contact times of different
user pairs are identical, we prove that the data offloading ratio increases
with the user moving speed, assuming that the transmission rate remains the
same. Simulation results are provided to show the accuracy of the approximate
result, and also validate the effect of user mobility.Comment: 6 pages, 5 figures, accepted to IEEE Int. Conf. Commun. (ICC), Paris,
France, May 201
Solar-neutrino reactions on deuteron in effective field theory
The cross sections for low-energy neutrino-deuteron reactions are calculated
within heavy-baryon chiral perturbation theory employing cut-off regularization
scheme. The transition operators are derived up to
next-to-next-to-next-to-leading order in the Weinberg counting rules, while the
nuclear matrix elements are evaluated using the wave functions generated by a
high-quality phenomenological NN potential. With the adoption of the
axial-current-four-nucleon coupling constant fixed from the tritium beta decay
data, our calculation is free from unknown low-energy constants. Our results
exhibit a high degree of stability against different choices of the cutoff
parameter, a feature which indicates that, apart from radiative corrections,
the uncertainties in the calculated cross sections are less than 1 %.Comment: 12 pages, 3 figures. Error estimation of higher order corrections
detaile
Warm Asymmetric Nuclear Matter and Proto-Neutron Star
Asymmetric nuclear matter equation of state at finite temperature is studied
in SU(2) chiral sigma model using mean field approximation. The effect of
temperature on effective mass, entropy, and binding energy is discussed.
Treating the system as one with two conserved charges the liquid-gas phase
transition is investigated. We have also discussed the effect of proton
fraction on critical temperature with and without -meson contribution. We
have extended our work to study the structure of proto-neutron star with
neutron free charge-neutral matter in beta-equilibrium. We found that the mass
and radius of the star decreases as it cools from the entropy per baryon S = 2
to S = 0 and the maximum temperature of the core of the star is about 62 MeV
for S = 2.Comment: 25 pages, 16 figure
Journey of water in pine cones
Pine cones fold their scales when it rains to prevent seeds from short-distance dispersal. Given that the scales of pine cones consist of nothing but dead cells, this folding motion is evidently related to structural changes. In this study, the structural characteristics of pine cones are studied on micro-/macro-scale using various imaging instruments. Raindrops fall along the outer scales to the three layers (bract scales, fibers and innermost lignified structure) of inner pine cones. However, not all the layers but only the bract scales get wet and then, most raindrops move to the inner scales. These systems reduce the amount of water used and minimize the time spent on structural changes. The result shows that the pine cones have structural advantages that could influence the efficient motion of pine cones. This study provides new insights to understand the motion of pine cones and would be used to design a novel water transport system.119Ysciescopu
Asymmetry of localised states in a single quantum ring: polarization dependence of excitons and biexcitons
We performed spectroscopic studies of a single GaAs quantum ring with an
anisotropy in the rim height. The presence of an asymmetric localised state was
suggested by the adiabatic potential. The asymmetry was investigated in terms
of the polarization dependence of excitons and biexcitons, where a large energy
di erence (0.8 meV) in the exciton emission energy for perpendicular
polarizations was observed and the oscillator strengths were also compared
using the photoluminescence decay rate. For perpendicular polarizations the
biexciton exhibits twice the energy di erence seen for the exciton, a fact that
may be attributed to a possible change in the selection rules for the lowered
symmetry.Comment: accepted in Applied physics Letter
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