Collapsing strange quark matter in Vaidya geometry

Exact solutions of the gravitational field equations for a mixture of a null charged strange quark fluid and radiation are obtained in a Vaidya space-time. The conditions for the formation of a naked singularity are analyzed by considering the behavior of radial geodesics originating from the central singularity.Comment: 6 pages, no figure

Responses of wild Vigna species/sub-species to yellow mosaic disease viruses, detected by a PCR-based method

Forty-eight accessions of wild Vigna species/sub-species were grown to verify their reactions to yellow mosaic disease (YMD), under field conditions in New Delhi (India) during 2012 and 2013. Symptoms of YMD that developed on wild Vigna were similar to those observed on cultivated species. Symptomatic plants produced few flowers and pods with reduced seed size. The infection coefficient was in the range of 0–71%. The causal virus was identified by PCR using species-specific primers to detect all the four viruses responsible for YMD in pulse crops. All the YMD-affected wild Vigna species/sub-species accessions were infected by Mungbean yellow mosaic India virus (MYMIV), with positive amplification of the targeted DNA fragment, except one accession of V. hainiana (IC331450) which was infected with Mungbean yellow mosaic virus. This indicated that MYMIV is the predominant virus causing yellow mosaic in wild species/sub-species of Vigna at New Delhi. Eight accessions belonging to V. synthetic allotetraploid, V. umbellata, V. mungo var. mungo, V. trilobata, V. trinervia var. bourneae, V. radiata var. sublobata and V. dalzelliana were completely free from YMD and gave negative PCR results with primers specific to all the four viruses. This confirms resistance to YMD in these wild Vigna species

Gravitational collapse of a Hagedorn fluid in Vaidya geometry

The gravitational collapse of a high-density null charged matter fluid, satisfying the Hagedorn equation of state, is considered in the framework of the Vaidya geometry. The general solution of the gravitational field equations can be obtained in an exact parametric form. The conditions for the formation of a naked singularity, as a result of the collapse of the compact object, are also investigated. For an appropriate choice of the arbitrary integration functions the null radial outgoing geodesic, originating from the shell focussing central singularity, admits one or more positive roots. Hence a collapsing Hagedorn fluid could end either as a black hole, or as a naked singularity. A possible astrophysical application of the model, to describe the energy source of gamma-ray bursts, is also considered.Comment: 14 pages, 2 figures, to appear in Phys. Rev.

Ultra-fast yttrium hydride chemistry at high pressures via non-equilibrium states induced by x-ray free electron laser

Controlling the formation and stoichiometric content of desired phases of materials has become a central interest for the study of a variety of fields, notably high temperature superconductivity under extreme pressures. The further possibility of accessing metastable states by initiating reactions by x-ray triggered mechanisms over ultra-short timescales is enabled with the development of x-ray free electron lasers (XFEL). Utilizing the exceptionally high brilliance x-ray pulses from the EuXFEL, we report the synthesis of a previously unobserved yttrium hydride under high pressure, along with non-stoichiometric changes in hydrogen content as probed at a repetition rate of 4.5\,MHz using time-resolved x-ray diffraction. Exploiting non-equilibrium pathways we synthesize and characterize a hydride with yttrium cations in an \textit{A}15 structure type at 125\,GPa, predicted using crystal structure searches, with a hydrogen content between 4.0--5.75 hydrogens per cation, that is enthalpically metastable on the convex hull. We demonstrate a tailored approach to changing hydrogen content using changes in x-ray fluence that is not accessible using conventional synthesis methods, and reveals a new paradigm in metastable chemical physics

USE OF WEB RESOURCES AND SERVICES BY THE RESEARCH SCHOLARS IN THE FIELD OF SOCIAL SCIENCES OF SELECTED CENTRAL UNIVERSITIES (DU, BHU, AMU, JNU)

The current study was conducted with the objective to study the usage of Web Resources and services by the Researchers in the field of social sciences of selected Central Universities (DU, BHU, AMU, JNU). A well-structured questionnaire was directed through irregular testing strategy to the Research Scholars of the Institutes to gather the information with respect to the utilization of Web Resources. This paper confines the investigation only to utilization of Web Resources by Researcher of Language and Literature in selected Central Universities (DU, BHU, AMU, JNU). The extent of the examination can be stretched out to former Indian Universities moreover. The investigation uncovers that Web Resources have turned into a fundamental piece of the examination works in these Universitie

Factors Influencing User Acceptance of Digital Libraries: Banaras Hindu University and Mahatma Gandhi Kashi Vidyapeeth University

The study is conducted with the evaluation factor for user acceptance of digital libraries in India: A study of the University of Varanasi (BHU and MGKVP). Banaras Hindu University is explaining the role of digital libraries in universities by looking at the benefits of digital libraries, their applications, and their services. It is discussing the drawbacks of digital libraries and the challenges encountered in implementing digital libraries as resources in education. Since digital libraries are unique and creative information structures that are constantly evolving and changing, assessment is critical to ensuring not just their proper progression but also their adoption by the students. To increase education and public interest, information and communication technology (ICT) has been commonly used in digital library systems. Researchers can reliably access relevant knowledge by browsing the internet. Educational and cultural dimensions are included in the use of digital libraries, such as knowledge opportunities. A digital archive deals with data that is digital and has been digitised from analogue form