Bulk viscous cosmological model in Brans Dicke theory with new form of time varying deceleration parameter

In this article we have presented FRW cosmological model in the framework of Brans-Dicke theory. This paper deals with a new proposed form of deceleration parameter and cosmological constant. The effect of bulk viscosity is also studied in the presence of modified Chaplygin gas equation of state. Further, we have discussed the physical behaviors of the models.Comment: 16 pages, 24 figures, Accepted in Advances in high energy physics, 201

Using indirect methods to understand the impact of forced migration on long-term under-five mortality.

Despite the large numbers of displaced persons and the often-lengthy periods of displacement, little is known about the impact of forced migration on long-term under-five mortality. This paper looks at the Brass Method (and adaptations of this method) and the Preceding Birth Technique in combination with a classification of women by their migration and reproductive histories, in order to study the impact of forced migration on under-five mortality. Data came from the Demography of Forced Migration Project, a study on mortality, fertility and violence in the refugee and host populations of Arua District, Uganda and Yei River District, Sudan. Results indicate that women who did not migrate in a situation of conflict and women who repatriated before the age of 15, had children with the highest under-five mortality rates compared with women who were currently refugees and women who repatriated after the age of 15

All fiber polarization insensitive detection for spectrometer based optical coherence tomography using optical switch

Polarization dependent image artifacts are common in optical coherence tomography imaging. Polarization insensitive detection scheme for swept source based optical coherence tomography systems is well established but is yet to be demonstrated for all fiber spectrometer-based Fourier domain optical coherence tomography systems. In this work, we present an all fiber polarization insensitive detection scheme for spectrometer based optical coherence tomography systems. Images from chicken breast muscle tissue were acquired to demonstrate the effectiveness of this scheme for the conventional Fourier domain optical coherence tomography system

Heat capacity and magnetoresistance in Dy(Co,Si)2 compounds

Magnetocaloric effect and magnetoresistance have been studied in Dy(Co1-xSix)2 [x=0, 0.075 and 0.15] compounds. Magnetocaloric effect has been calculated in terms of adiabatic temperatue change (Delta Tad) as well as isothermal magnetic entropy change (Delta SM) using the heat capacity data. The maximum values of DeltaSM and DeltaTad for DyCo2 are found to be 11.4 JKg-1K-1 and 5.4 K, respectively. Both DSM and DTad decrease with Si concentration, reaching a value of 5.4 JKg-1K-1 and 3 K, respectively for x=0.15. The maximum magnetoresistance is found to about 32% in DyCo2, which decreases with increase in Si. These variations are explained on the basis of itinerant electron metamagnetism occurring in these compounds.Comment: Total 8 pages of text and figure

Dynamics of Uniform Quantum Gases, I: Density and Current Correlations

A unified approach valid for any wavenumber, frequency, and temperature is presented for uniform ideal quantum gases allowing for a comprehensive study of number density and particle-current density response functions. Exact analytical expressions are obtained for spectral functions in terms of polylogarithms. Also, particle-number and particle-current static susceptibilities are presented which, for fugacity less than unity, additionally involve Kummer functions. The wavenumber and temperature dependent transverse-current static susceptibility is used to show explicitly that current correlations are of a long range in a Bose-condensed uniform ideal gas but for bosons above the critical temperature and for Fermi and Boltzmann gases at all temperatures these correlations are of short range. Contact repulsive interactions for systems of neutral quantum particles are considered within the random-phase approximation. The expressions for particle-number and transverse-current susceptibilities are utilized to discuss the existence or nonexistence of superfluidity in the systems under consideration

A 10-day ASCA Observation of the Narrow-line Seyfert~1 galaxy IRAS 13224-3809

(Abridged) We present an analysis of a 10-day continuous ASCA observation of the narrow-line Seyfert 1 galaxy IRAS 13224-3809. The soft (0.7-1.3 keV) and hard (1.3-10 keV) X-ray band light curves binned to 5000s reveal trough-to-peak variations by a factor >25 and 20, respectively. The light curves in the soft and hard bands are strongly correlated without any significant delay. However, this correlation is not entirely due to changes in the power-law flux alone but also due to changes in the soft X-ray hump emission above the power law. The presence of a soft X-ray hump below 2 keV, previously detected in ROSAT and ASCA data, is confirmed. Time resolved spectroscopy using daily sampling reveals changes in the power-law slope, with Gamma in the range 1.74-2.47, however, day-to-day variations in Gamma are not significant. The Soft hump emission is found to dominate the observed variability on a timescale of a week, but on shorter timescales (20000s) the power-law component appears to dominate the observed variability. Flux resolved spectroscopy reveals that at high flux levels the power law becomes steeper and the soft hump more pronounced. The steepening of the photon index with the fluxes in the soft and hard bands can be understood in the framework of disk/corona models in which accretion disk is heated by viscous dissipation as well as by reprocessing of hard X-rays following an X-ray flare resulting from coronal dissipation through magnetic reconnection events.Comment: 29 pages, 16 figures, To apear in A&

Heat capacity and magnetocaloric effect in polycrystalline Gd1-xSmxMn2Si2

We report the magnetocaloric effect in terms of isothermal magnetic entropy change as well as adiabatic temperature change, calculated using the heat capacity data. Using the zero field heat capacity data, the magnetic contribution to the heat capacity has been estimated. The variations in the magnetocaloric behavior have been explained on the basis of the magnetic structure of these compounds. The refrigerant capacities have also been calculated for these compounds

Multiple magnetic transitions and magnetocaloric effect in Gd1-xSmxMn2Ge2 compounds

Magnetic and magnetocaloric properties of polycrystalline samples of Gd1-xSmxMn2Ge2 have been studied. All the compounds except GdMn2Ge2 show re-entrant ferromagnetic behavior. Multiple magnetic transitions observed in these compounds are explained on the basis of the temperature dependences of the exchange strengths of the rare earth and Mn sublattices. Magnetocaloric effect is found to be positive at the re-entrant ferromagnetic transition, whereas it is negative at the antiferro-ferromagnetic transition. In SmMn2Ge2, the magnetic entropy change associated with the re-entrant transition is found to decrease with field, which is attributed to the admixture effect of the crystal field levels. The isothermal magnetic entropy change is found to decrease with increase in Sm concentration.Comment: