1,855 research outputs found

    High bat (Chiroptera) diversity in the Early Eocene of India

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    The geographic origin of bats is still unknown, and fossils of earliest bats are rare and poorly diversified, with, maybe, the exception of Europe. The earliest bats are recorded from the Early Eocene of North America, Europe, North Africa and Australia where they seem to appear suddenly and simultaneously. Until now, the oldest record in Asia was from the Middle Eocene. In this paper, we report the discovery of the oldest bat fauna of Asia dating from the Early Eocene of the Cambay Formation at Vastan Lignite Mine in Western India. The fossil taxa are described on the basis of well-preserved fragments of dentaries and lower teeth. The fauna is highly diversified and is represented by seven species belonging to seven genera and at least four families. Two genera and five species are new. Three species exhibit very primitive dental characters, whereas four others indicate more advanced states. Unexpectedly, this fauna presents strong affinities with the European faunas from the French Paris Basin and the German Messel locality. This could result from the limited fossil record of bats in Asia, but could also suggest new palaeobiogeographic scenarios involving the relative position of India during the Early Eocene

    Electron-Hole Generation and Recombination Rates for Coulomb Scattering in Graphene

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    We calculate electron-hole generation and recombination rates for Coulomb scattering (Auger recombination and impact ionization) in Graphene. The conduction and valence band dispersion relation in Graphene together with energy and momentum conservation requirements restrict the phase space for Coulomb scattering so that electron-hole recombination times can be much longer than 1 ps for electron-hole densities smaller than 101210^{12} cm2^{-2}.Comment: 13 pages, 7 figure

    Lifetime of a nanodroplet : kinetic effects and regime transitions

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    A transition from a d2 to a d law is observed in molecular dynamics (MD) simulations when the diameter (d) of an evaporating droplet reduces to the order of the vapor’s mean free path; this cannot be explained by classical theory. This Letter shows that the d law can be predicted within the Navier-Stokes-Fourier (NSF) paradigm if a temperature-jump boundary condition derived from kinetic theory is utilized. The results from this model agree with those from MD in terms of the total lifetime, droplet radius, and temperature, while the classical d2 law underpredicts the lifetime of the droplet by a factor of 2. Theories beyond NSF are also employed in order to investigate vapor rarefaction effects within the Knudsen layer adjacent to the interface

    A deep multi-modal neural network for informative Twitter content classification during emergencies

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    YesPeople start posting tweets containing texts, images, and videos as soon as a disaster hits an area. The analysis of these disaster-related tweet texts, images, and videos can help humanitarian response organizations in better decision-making and prioritizing their tasks. Finding the informative contents which can help in decision making out of the massive volume of Twitter content is a difficult task and require a system to filter out the informative contents. In this paper, we present a multi-modal approach to identify disaster-related informative content from the Twitter streams using text and images together. Our approach is based on long-short-term-memory (LSTM) and VGG-16 networks that show significant improvement in the performance, as evident from the validation result on seven different disaster-related datasets. The range of F1-score varied from 0.74 to 0.93 when tweet texts and images used together, whereas, in the case of only tweet text, it varies from 0.61 to 0.92. From this result, it is evident that the proposed multi-modal system is performing significantly well in identifying disaster-related informative social media contents

    Evaporation-driven vapour micro flows : analytical solutions from moment methods

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    Macroscopic models based on moment equations are developed to describe the transport of mass and energy near the phase boundary between a liquid and its rarefied vapour due to evaporation and hence, in this study, condensation. For evaporation from a spherical droplet, analytic solutions are obtained to the linearised equations from the Navier–Stokes–Fourier, regularised 13-moment and regularised 26-moment frameworks. Results are shown to approach computational solutions to the Boltzmann equation as the number of moments are increased, with good agreement for Knudsen number , whilst providing clear insight into non-equilibrium phenomena occurring adjacent to the interface

    A Study of Sexual Assaults in Northern Range of Himachal Pradesh

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    Background: Rape is among the highest forms of underreported crime experienced by women in all sections of the society and obtaining an accurate measurement of sexual assault is a challenge. An increasing rate of sexual assaults constitutes a large number of cases registered under different sections of the Indian law, their medico-legal examination and forensic investigations.Methods: The study was conducted on 35 sexual assaults cases received for examination at RFSL, Northern Range, Dharamshala, Himachal Pradesh, India. A self-innovated proforma including the details pertaining to socio-demographic profile, medical examination, and results of specimens of victims collected during forensic analysis was designed. Benzidine test, gel-diffusion test, acid phosphatase test and microscopic examinations were conducted in the lab.Results: The common location of offence was house of the accused (31.42%) followed by house of the victim (20.0%). 48.57% of the alleged rape victims were students. Highly affected age group was 11-20 years. Fifteen girls (42.85%) were below eighteen years of age, which was the age of invalid consensual rape. Forcible rape and invalid consensual rape was reported in 68.56% cases. 77.14% victims were unmarried and 22.85% were married. 85.71% victims were Hindus followed by Muslims (11.42%) and Christian (2.85%). 80% victims knew the assailant. Rupture of hymen was found in 88.57% cases and hymen was intact in 11.42% cases. Delay of medico-legal examination of victim was noted. 31.42% victims had combined genital and extra genital injuries. Acid phosphatase test was found positive in 34.28% cases and positivity for spermatozoa in 22.85% cases. Blood was detected on clothes, undergarments and vaginal swabs in 42.85% cases. In 8.55% cases rape was committed by family members. Only one victim became pregnant following the act of sexual intercourse.Conclusion: Cases were reported from Hindu, Muslim and Christian communities and adolescents were more at risk. Majority of the victims have acquaintance with the assailant and the residence of the accused was the most common location of sexual assault. Delay in medico-legal examination caused problems in detection of semen and spermatozoa. Most of the victims had bath and genital wash after the sexual act, before medical examination and destroyed the evidence

    Unsteady electromagnetic radiative nanofluid stagnation-point flow from a stretching sheet with chemically reactive nanoparticles, Stefan blowing effect and entropy generation

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    The present article investigates the combined influence of nonlinear radiation, Stefan blowing and chemical reactions on unsteady EMHD stagnation point flow of a nanofluid from a horizontal stretching sheet. Both electrical and magnetic body forces are considered. In addition, the effects of velocity slip, thermal slip and mass slip are considered at the boundaries. An analytical method named as homotopy analysis method is applied to solve the non-dimensional system of nonlinear partial differential equations which are obtained by applying similarity transformations on governing equations. The effects of emerging parameters including Stefan blowing parameter, electric parameter, magnetic parameter etc. on the important physical quantities are presented graphically. Additionally, an entropy generation analysis is provided in this article for thermal optimization. The flow is observed to be accelerated both with increasing magnetic field and electrical field. Entropy generation number is markedly enhanced with greater magnetic field, electrical field and Reynolds number, whereas it is reduced with increasing chemical reaction parameter

    Role of Fe substitution on the anomalous magnetocaloric and magnetoresistance behavior in Tb(Ni1-xFex)2 compounds

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    We report the magnetic, magnetocaloric and magnetoresistance results obtained in Tb(Ni1-xFex)2 compounds with x=0, 0.025 and 0.05. Fe substitution leads to an increase in the ordering temperature from 36 K for x=0 to 124 K for x=0.05. Contrary to a single sharp MCE peak seen in TbNi2, the MCE peaks of the Fe substituted compounds are quite broad. We attribute the anomalous MCE behavior to the randomization of the Tb moments brought about by the Fe substitution. Magnetic and magnetoresistance results seem to corroborate this proposition. The present study also shows that the anomalous magnetocaloric and magnetoresistance behavior seen in the present compounds is similar to that of Ho(Ni,Fe)2 compounds

    Chandra High Resolution X-ray Spectroscopy of AM Her

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    We present the results of high resolution spectroscopy of the prototype polar AM Herculis observed with Chandra High Energy Transmission Grating. The X-ray spectrum contains hydrogen-like and helium-like lines of Fe, S, Si, Mg, Ne and O with several Fe L-shell emission lines. The forbidden lines in the spectrum are generally weak whereas the hydrogen-like lines are stronger suggesting that emission from a multi-temperature, collisionally ionized plasma dominates. The helium-like line flux ratios yield a plasma temperature of 2 MK and a plasma density 1 - 9 x10^12 cm^-3, whereas the line flux ratio of Fe XXVI to Fe XXV gives an ionization temperature of 12.4 +1.1 -1.4 keV. We present the differential emission measure distribution of AM Her whose shape is consistent with the volume emission measure obtained by multi-temperature APEC model. The multi-temperature plasma model fit to the average X-ray spectrum indicates the mass of the white dwarf to be ~1.15 M_sun. From phase resolved spectroscopy, we find the line centers of Mg XII, S XVI, resonance line of Fe XXV, and Fe XXVI emission modulated by a few hundred to 1000 km/s from the theoretically expected values indicating bulk motion of ionized matter in the accretion column of AM Her. The observed velocities of Fe XXVI ions are close to the expected shock velocity for a 0.6 M_sun white dwarf. The observed velocity modulation is consistent with that expected from a single pole accreting binary system.Comment: 6 figures, AASTEX style, accepted for publication in Ap
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