Polar phonons and spin-phonon coupling in HgCr2S4 and CdCr2S4

Polar phonons of HgCr2S4 and CdCr2S4 are studied by far-infrared spectroscopy as a function of temperature and external magnetic field. Eigenfrequencies, damping constants, effective plasma frequencies and Lyddane-Sachs-Teller relations, and effective charges are determined. Ferromagnetic CdCr2S4 and antiferromagnetic HgCr2S4 behave rather similar. Both compounds are dominated by ferromagnetic exchange and although HgCr2S4 is an antiferromagnet, no phonon splitting can be observed at the magnetic phase transition. Temperature and magnetic field dependence of the eigenfrequencies show no anomalies indicating displacive polar soft mode behavior. However, significant effects are detected in the temperature dependence of the plasma frequencies indicating changes in the nature of the bonds and significant charge transfer. In HgCr2S4 we provide experimental evidence that the magnetic field dependence of specific polar modes reveal shifts exactly correlated with the magnetization showing significant magneto-dielectric effects even at infrared frequencies.Comment: 8 pages, 8 figure

Anti-Depressant Activity of Zizyphus xylopyrus

The present study was undertaken to investigate the effect of ethanolic extract (ext.), ethyl acetate (EA) fractions and precipitate fraction (ppt.) of total ethanolic extract of Zizyphus xylopyrus on depression in rats. In the present study, the antidepressant effect of Zizyphus xylopyrus was examined using two behavioral models, the forced swimming test (FST) in rats and tail suspension test (TST) in rats.Ethanolic extract when administered at an acute dose of 50 mg/kg of body weight (P<0.01) reduced the immobility time by 10 and 15 seconds as compared to the immobility time of control in both the screening models. Similarly EA reduced latter by 30 and 35 secs. The ppt. fraction showed the best activity, reducing the immobility time by 50 and 60 secs. in both the tests. These results showed that after standard i.e. Imipramine HCl (30 mg/kg), the ppt. fraction is potent amongst all the studied drugsThe present study clearly demonstrated that Zizyphus xylopyrus exerts an antidepressant effect in these two behavioral models. It may be due to present of flavonoids.Keywords: Zizyphus xylopyrus, Flavanoides, forced swimming test, tail suspension test

Anti-Depressant Activity of Zizyphus xylopyrus

The present study was undertaken to investigate the effect of ethanolic extract (ext.), ethyl acetate (EA) fractions and precipitate fraction (ppt.) of total ethanolic extract of Zizyphus xylopyrus on depression in rats. In the present study, the antidepressant effect of Zizyphus xylopyrus was examined using two behavioral models, the forced swimming test (FST) in rats and tail suspension test (TST) in rats.Ethanolic extract when administered at an acute dose of 50 mg/kg of body weight (P<0.01) reduced the immobility time by 10 and 15 seconds as compared to the immobility time of control in both the screening models. Similarly EA reduced latter by 30 and 35 secs. The ppt. fraction showed the best activity, reducing the immobility time by 50 and 60 secs. in both the tests. These results showed that after standard i.e. Imipramine HCl (30 mg/kg), the ppt. fraction is potent amongst all the studied drugsThe present study clearly demonstrated that Zizyphus xylopyrus exerts an antidepressant effect in these two behavioral models. It may be due to present of flavonoids.Keywords: Zizyphus xylopyrus, Flavanoides, forced swimming test, tail suspension test

Decomposing Service Definition in Predicate/Transition-Nets for Designing Distributed Systems

In this paper, we propose a new algorithm for the derivation of a protocol specification in Pr/T-nets, which is the specification of communicating N entities (N can be given), from a given service specification in Pr/T-nets and an allocation of the places of the service specification to the N entities. Our algorithm decomposes each transition of the service specification into a set of communicating Pr/T-subnets running on the N entities. Moreover, for the efficient control of conflict of shared resources, we present a timestamp-based mutual exclusion algorithm and incorporate it into the derivation algorithm

Active nonreciprocal attraction between motile particles in an elastic medium

We present a theory for the interaction between motile particles in an elastic medium on a substrate, relying on two arguments: a moving particle creates a strikingly fore-aft asymmetric distortion in the elastic medium; this strain field reorients other particles. We show that this leads to sensing, attraction and pursuit, with a non-reciprocal character, between a pair of motile particles. We confirm the predicted distortion fields and non-mutual trail-following in our experiments and simulations on polar granular rods made motile by vibration, moving through a dense monolayer of beads in its crystalline phase. Our theory should be of relevance to the interaction of motile cells in the extracellular matrix or in a supported layer of gel or tissue.Comment: Revised, experimental results added, SI expanded to include fits, some figures and bibliography modified, See Supplementary movies here https://www.dropbox.com/sh/od5lg00cxijk7b9/AAB3j6el7jFdaZ0q1xOo0Eqza?dl=

Analysis of mechanical draft wet cooling towers

The objective of the paper is to present a review on the analysis of mechanical-draft wet cooling towers. Starting with the basic fundamentals of a cooling tower, an attempt is made here to present an analysis of the important computational models available. The physical situation within a cooling tower is very complex (films and droplets of water in air are in a constantly changing configuration). There is no mathematical model which is capable of simulating every detail of simultaneous heat and mass transfer process occurring within the tower. Consequently, simplifying assumptions must be made for the analysis. A comprehensive list of assumptions is provided which are used for the different models. Eight computational models are analyzed here, namely (a) ESC code, (b) FACTS, (c) VERAZD, (d) STAR, (e) Sutherland's Model, (f) Model by Fujita and Tezuka, (g) Webb's Model, (h) Model by Jaber and Webb. Each model makes use of somewhat different set of assumptions. So, the results of the calculations of heat/mass transfer coefficients also differ. Analysis of the above models gives us an idea about different numerical solutions of cooling tower design. It is difficult to draw general conclusions concerning the comperative merits of the correlations, or of the codes. Yet it is attempted here to compare the different models from the view point of design, computational error, computational time, simplicity of usage and practicability

Testing general relativity using golden black-hole binaries

The coalescences of stellar-mass black-hole binaries through their inspiral, merger, and ringdown are among the most promising sources for ground-based gravitational-wave (GW) detectors. If a GW signal is observed with sufficient signal-to-noise ratio, the masses and spins of the black holes can be estimated from just the inspiral part of the signal. Using these estimates of the initial parameters of the binary, the mass and spin of the final black hole can be uniquely predicted making use of general-relativistic numerical simulations. In addition, the mass and spin of the final black hole can be independently estimated from the merger--ringdown part of the signal. If the binary black hole dynamics is correctly described by general relativity (GR), these independent estimates have to be consistent with each other. We present a Bayesian implementation of such a test of general relativity, which allows us to combine the constraints from multiple observations. Using kludge modified GR waveforms, we demonstrate that this test can detect sufficiently large deviations from GR, and outline the expected constraints from upcoming GW observations using the second-generation of ground-based GW detectors.Comment: 5 pages, 2 fig

Parametrized tests of post-Newtonian theory using Advanced LIGO and Einstein Telescope

General relativity has very specific predictions for the gravitational waveforms from inspiralling compact binaries obtained using the post-Newtonian (PN) approximation. We investigate the extent to which the measurement of the PN coefficients, possible with the second generation gravitationalwave detectors such as the Advanced Laser Interferometer Gravitational-Wave Observatory (LIGO) and the third generation gravitational-wave detectors such as the Einstein Telescope (ET), could be used to test post-Newtonian theory and to put bounds on a subclass of parametrized-post-Einstein theories which differ from general relativity in a parametrized sense. We demonstrate this possibility by employing the best inspiralling waveform model for nonspinning compact binaries which is 3.5PN accurate in phase and 3PN in amplitude. Within the class of theories considered, Advanced LIGO can test the theory at 1.5PN and thus the leading tail term. Future observations of stellar mass black hole binaries by ET can test the consistency between the various PN coefficients in the gravitational-wave phasing over the mass range of 11-44 Msun. The choice of the lower frequency cut off is important for testing post-Newtonian theory using the ET. The bias in the test arising from the assumption of nonspinning binaries is indicated.Comment: 18 pages, 11 figures, Matches with the published versio