3,879 research outputs found
Photon redshift and the appearance of a naked singularity
In this paper we analyze the redshift as observed by an external observer
receiving photons which terminate in the past at the naked singularity formed
in a Tolman-Bondi dust collapse. Within the context of models considered here
it is shown that photons emitted from a weak curvature naked singularity are
always finitely redshifted to an external observer. Certain cases of strong
curvature naked singularities, including the self-similar one, where the
photons are infinitely redshifted are also pointed out.Comment: Latex file, 14 pages, no figures, one change in the reference.
Accepted for publication in Phys. Rev.
Semiclassical triton
The symmetric components of the spatial part of - and - states'
wavefunctions for triton are investigated utilizing semiclassical
expansion (in the powers of ). Analysis of the diagonalized Hamiltonian
reveals the existence of two different mass states within the ground state of
triton. We have solved the coupled differential equations for the two admixed
states and owing to tensor interactions exploiting
classical WKB-theory using phenomenological Feshbach-Pease potentials. The
relative probability of the -state is found to be in good agreement with the
experimentally inferred value (4 - 5 \%)
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Techno-Economic Analysis of Hybrid Layered Manufacturing
Subtractive manufacturing (CNC machining) has high quality of geometric and
material properties but is slow, costly and infeasible in some cases; additive
manufacturing (RP) is just the opposite. Total automation and hence speed is
achieved in RP by compromising on quality. Hybrid Layered Manufacturing
(HLM) developed at IIT Bombay combines the best features of both these
approaches. It uses arc welding for building near-net shapes which are finish
machined to final dimensions. High speed of HLM surpasses all other processes
for tool making by eliminating NC programming and rough machining. The
techno-economic viability of HLM process has been proved through a real life
case study. Time and cost of tool making using HLM promises to be substantially
lower than that of CNC machining and other RP methods. Interestingly, the
material cost in HLM was also found to be lower. HLM is a cheaper retrofitment
to any 3 or 5 axis CNC milling machine or machining center.Mechanical Engineerin
Assessment of genetic diversity among collected genotypes of Chlorophytum borivilianum using random amplified polymorphic DNA (RAPD) markers
Chlorophytum borivilianum (Family: Liliaceae), an important threatened medicinal herb is designated as ‘Rare’ in Red Data Book of Indian plants. Morphological as well as biochemical markers used in the authentication of herbal drugs have many limitations due to the impact of environmental conditions. Molecular markers therefore, are an important tool in quality assurance and preservation of germplasm of medicinal plant species in the plant kingdom. In this study, RAPD markers were used to assess genetic diversity in nine genotypes of C. borivilianum collected from different geographical regions of Chhattisgarh, Madhya Pradesh and Uttar Pradesh. Out of the 43 bands obtained, 26 were polymorphic, with (67.49) percent polymorphism, thus, revealing a high degree of polymorphism. Percentage of polymorphism detected with each primer was as high as 80.00 (OP L18) and as low as 33.30 (OP L12). The Jaccard’s similarity coefficient ranged from 0.609 to 0.810. The maximum similarity value was noticed between V3 and V5 genotypes collected from Lamni (C.G.) and Chitrakoot (U.P.),respectively.Keywords: Genetic diversity, random amplified polymorphic DNA (RAPD)-PCR, UPGMA, Chlorophytumborivilianum
Polyherbal Formulation used in the Treatment of Jaundice
Plants have traditionally served as man\u27s most important weapon against pathogens. Herbal medicines are widely used by all sections of the community, either as folk remedies or as medicaments in the indigenous as well as modern system of medicine. The present work was performed to enumerate the medicinal herbs that tribes and rural people uses for the treatment of jaundice. Data were collected by interviewing local traditional therapists and tribes of the region. Details of 10 herbs and 03 formulations were gathered along with their doses, duration and formulations during the course of present investigation in the study area. Our study revealed that all above herbs and their formulations have been used since quite a long time by the tribes and rural people and no side/ adverse effects were reported
Formulation and Evaluation of Polyherbal Anthelmintic Preparation
The present study was done with the aim to formulate an anthelmintic preparation and to evaluate anthelmintic activity of formulation containing traditionally user herbs viz., Plumbago zeylanica (leaves), Hyoscyamus niger (roots) and Abultion indicum (leaves) using adult earthworm Pheritima posthuma. The aqueous and ethanolic extract of the crude drug of different concentration were tested which involve determination of paralysis time and time to kill the worms. Piperazine citrate was used as standard and it was found that the PHFEE activity is higher than PHFAE
Initial data and the end state of spherically symmetric gravitational collapse
Generalizing earlier results on the initial data and the final fate of dust
collapse, we study here the relevance of the initial state of a spherically
symmetric matter cloud towards determining its end state in the course of a
continuing gravitational collapse. It is shown that given an arbitrary regular
distribution of matter at the initial epoch, there always exists an evolution
from this initial data which would result either in a black hole or a naked
singularity depending on the allowed choice of free functions available in the
solution. It follows that given any initial density and pressure profiles for
the cloud, there is a non-zero measure set of configurations leading either to
black holes or naked singularities, subject to the usual energy conditions
ensuring the positivity of energy density. We also characterize here wide new
families of black hole solutions resulting from spherically symmetric collapse
without requiring the cosmic censorship assumption.Comment: Ordinary Tex file, 31 pages no figure
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