Hydrostatic equilibrium of insular, static, spherically symmetric, perfect fluid solutions in general relativity

An analysis of insular solutions of Einstein's field equations for static, spherically symmetric, source mass, on the basis of exterior Schwarzschild solution is presented. Following the analysis, we demonstrate that the {\em regular} solutions governed by a self-bound (that is, the surface density does not vanish together with pressure) equation of state (EOS) or density variation can not exist in the state of hydrostatic equilibrium, because the source mass which belongs to them, does not represent the `actual mass' appears in the exterior Schwarzschild solution. The only configuration which could exist in this regard is governed by the homogeneous density distribution (that is, the interior Schwarzschild solution). Other structures which naturally fulfill the requirement of the source mass, set up by exterior Schwarzschild solution (and, therefore, can exist in hydrostatic equilibrium) are either governed by gravitationally-bound regular solutions (that is, the surface density also vanishes together with pressure), or self-bound singular solutions (that is, the pressure and density both become infinity at the centre).Comment: 16 pages (including 1 table); added section 5; accepted for publication in Modern Physics Letters

Generalized Electromagnetic fields in Chiral Medium

The time dependent Dirac-Maxwell's Equations in presence of electric and magnetic sources are written in chiral media and the solutions for the classical problem are obtained in unique simple and consistent manner. The quaternion reformulation of generalized electromagnetic fields in chiral media has also been developed in compact, simple and consistent manner

Exploration, collection and conservation of multicrop germplasm from Kishtwar district of Jammu and Kashmir, India

Systematic exploration and germplasm collection trips were conducted across Kishtwar district of Jammu and Kashmir state covering Chatroo valley, Padder valley and Kishtwar main including areas of Dachan, Surror, Sarthal, Bhonjwa and Drabshala during 2013, 2015 and 2018. A total of 113 germplasm accessions belonging to 29 species of crops and wild relatives from as many as 40 collection sites were collected at altitudes ranging from 1340-2670 m. Several areas in Sarthal, Bhonjwa, Dachan and Gulabgarh Padder were first time explored. Crop group wise accessions collected are pulses (39) mostly common beans, cereals (30) mostly maize, vegetables and spices (25), pseudocereals and millets (16), besides one accession each of Glycine max, Solanum pseudocapsicum and Nicotiana tabacum. The germplasm has been conserved in National Gene Bank (NGB), New Delhi. This study highlights information on the germplasm collected/observed and threats leading to biodiversity loss/genetic erosion in the highly fragile region of Kishtwar

Oral medicine case book 76: Methotrexate induced mucosal erosions and ulcerations

A 71-year-old male was referred from his general practitioner to the Oral Medicine Clinic at the University of the Western Cape, Oral Health Centre, Tygerberg campus, on account of a six-week history of recurrent oral ulceration

Ferromagnetism and ferroelectricity in highly resistive Pb(0.7)Sr(0.3)(Fe(0.012)Ti(0.988))O(3) nanoparticles and its conduction by variable-range-hopping mechanism

The enhancement in ferromagnetism and ferroelectricity at room temperature for Pb0.7Sr0.3�Fe0.012Ti0.988�O3 �PSFT� nanoparticles is proved by magnetization and polarization hysteresis loop. The x-ray diffraction and micrograph show that the PSFT nanoparticles have distorted tetragonal single phase, and their average particle’s size is 8 nm. The effect of Sr content reduces the particle size, and hence the multiferroic system becomes more resistive, which dominates the superparamagnetic/paraelectric relaxation. The variable-range-hopping conduction mechanism explained the high resistivity of PSFT nanoparticles, which suggests that the room temperature movement of electrons involves short-range order through defect states

Nanotechnology Applications for Chemical and Biological Sensors

Recent discoveries indicate that when the materials are brought down to sizes in the range 1–100 nm, theseexhibit unique electrical, optical, magnetic, chemical, and mechanical properties. Methods have now beenestablished to obtain the monodisperse nanocrystals of various metallic and semiconducting materials, single-walled and multi-walled nanotubes of carbon and other metallic and non-metallic materials together withorganic nanomaterials such as supra-molecular nanostructures, dendrimers, hybrid composites with tailoredfunctionalities. The high surface-to-volume ratio with an added element of porosity makes these highly potentialcandidates for chemical and biological sensor applications with higher degree of sensitivity and selectivity ascompared to their bulk counterparts. The paper reviews the recent developments and applications of chemicaland biological sensors based on nanomaterials of various structural forms.Defence Science Journal, 2008, 58(5), pp.636-649, DOI:http://dx.doi.org/10.14429/dsj.58.168