7,905 research outputs found
Spinning Test Particle in Kalb-Ramond background
In this work we explore the geodesic deviations of spinning test particles in
a string inspired Einstein-Kalb Ramond background. Such a background is known
to be equivalent to a spacetime geometry with torsion. We have shown here that
the antisymmetric Kalb-Ramond field has significant effect on the geodesic
deviation of a spinning test particle. A search for an observational evidence
of such an effect in astrophysical experiments may lead to a better
undestanding of the geometry of the background spacetime.Comment: 14 pages, Latex, 5 figure
Bulk Kalb-Ramond field in Randall Sundrum scenario
We have considered the most general gauge invariant five-dimensional action
of a second rank antisymmetric Kalb-Ramond tensor gauge theory, including a
topological term of the form in a
Randall-Sundrum scenario. Such a tensor field (whose rank-3 field
strength tensor is ), which appears in the massless sector of a
heterotic string theory, is assumed to coexist with the gravity in the bulk.
The third rank field strength corresponding to the Kalb-Ramond field has a
well-known geometric interpretation as the spacetime torsion. The only
non-trivial classical solutions corresponding to the effective four-dimensional
action are found to be self-dual or anti-selfdual Kalb-Ramond fields. This
ensures that the four-dimensional effective action on the brane is
parity-conserving. The massive modes for both cases, lying in the TeV range,
are related to the fundamental parameters of the theory. These modes can be
within the kinematic reach of forthcoming TeV scale experiments. However, the
couplings of the massless as well as massive Kalb-Ramond modes with matter on
the visible brane are found to be suppressed vis-a-vis that of the graviton by
the warp factor, whence the conclusion is that both the massless and the
massive torsion modes appear much weaker than curvature to an observer on the
visible brane.Comment: 15 Pages,2 figures,Late
Synthetic Polymer Based Coating of Fodder Cowpea Seeds Enhances Germination and Vigour
In Indian arid and semi-arid conditions, comparatively less fertile lands are allotted to forage crops. In addition, erratic weather condition makes the situation more complex where proper seedling emergence and establishment of pastures with economic use of input remains a big question. Our view is that crop seedling production from seed sown into arid or semiarid environments could be significantly enhanced by the use of simple seed coating technologies. Such approaches would make use of newly synthesised seed coat-applied polymers that could be used to hold the desired supplements like powerful germination enhancement chemicals and plant protectants with seed to support both germination and seedling establishment under the crucial stages. This approach would be expected to increase the rate and speed of germination, thereby bringing the uniformity in plant population even under stressful (drought) growing conditions. On the other hand, cowpea seed are highly susceptible to insect pest during storage in addition to seed borne diseases. Hence, coating of seed was envisaged in order to protect the seeds from pest attack and boost initial seedling vigour
Constraining the Randall-Sundrum modulus in the light of recent PVLAS data
Recent PVLAS data put stringent constraints on the measurement of
birefringence and dichroism of electromagnetic waves travelling in a constant
and homogeneous magnetic field. There have been theoretical predictions in
favour of such phenomena when appropriate axion-electromagnetic coupling is
assumed. Origin of such a coupling can be traced in a low energy string action
from the requirement of quantum consistency. The resulting couplings in such
models are an artifact of the compactification of the extra dimensions present
inevitably in a string scenario. The moduli parameters which encode the compact
manifold therefore play a crucial role in determining the axion-photon
coupling. In this work we examine the possible bounds on the value of compact
modulus that emerge from the experimental limits on the coupling obtained from
the PVLAS data. In particular we focus into the Randall-Sundrum (RS) type of
warped geometry model whose modulus parameter is already restricted from the
requirement of the resolution of gauge hierarchy problem in connection with the
mass of the Higgs. We explore the bound on the modulus for a wide range of the
axion mass for both the birefringence and the dichroism data in PVLAS. We show
that the proposed value of the modulus in the RS scenario can only be
accommodated for axion mass \gsim 0.3 eV.Comment: 26 pages, 1 figure, LaTex; added references, typos corrected. Minor
changes in the text, a comment added in the Conclusio
PASTEURELLOSIS IN DUCK IN WEST BENGAL
Two hundred sixty four samples were collected from heart blood, liver, spleen and femur of 85 khaki Campbell ducks of which P. multocida could be isolated from 4 (4.70%) birds. Out of 4 samples, organisms could be isolated from heart blood of one ducklings liver and femur of one duck each. All the isolates were found positive to catalase, oxidase, indole, nitrate reduction test and negative to methyl red, Voges-Proskaur, citrate utilization,
H2S production and triple sugar iron test. The isolates fermented glucose and manitol without production of gas and non-fermented lactose, salicin, dulcitol and inositol. The isolates were non-motile and pathogenic to mice. All isolates of P. multocida were sensitive to amoxiclav, chloramphenicol, gentamicin and three isolates were sensitive to co-trimoxazole. All were moderately sensitive to amikacin, cefotaxime, neomycin and norfloxacin and resistant
to ciprofloxacin and lomefloxacin
Charged black holes in generalized dilaton-axion gravity
We study generic Einstein-Maxwell-Kalb-Ramond-dilaton actions, and derive
conditions under which they give rise to static, spherically symmetric black
hole solutions. We obtain new asymptotically flat and non-flat black hole
solutions which are in general electrically and magnetically charged. They have
positive definite and finite quasi-local masses. Existing non-rotating black
hole solutions (including those appearing in low energy string theory) are
recovered in special limits.Comment: Replaced with revised version, 33 pages, No figure
Anthesis Dynamics, Pollen Availability and Enhancement of Seed to Ovule Ratio in \u3cem\u3eChrysopogon fulvus\u3c/em\u3e
Under the present scenario of severe green fodder shortage (64%) in India, grassland offers an opportunity to enhance fodder availability. To revitalize the existing denuded grasslands, seed is the best propagating material. Availability of quality seed in forage grasses is less than 20% of actual requirement/ demand. Hence, there is a need to enhance the production and productivity of grass seeds. Even the available grass seeds have very low germination percentage, which is mainly due to the absence of a caryopsis inside the fluffy seed material. Chrysopogon fulvus, commonly known as Guria grass or red false beard grass, is a tufted perennial tropical grassland species, with good palatability and green fodder potential of \u3e20 t/ha. With its ability to grow under annual rainfall of 300-1200 mm it is well suited for the rainfed situation of Indian grasslands.
As per Indian minimum seed certification standards (IMSCS), the germination percentage of C. fulvus is only 15%. The low germination coincides with the low seed setting (14-18%) as recorded in bulk harvested sample by Bahukhandi et al. (2011). Enhancement of seed to ovule ratio not only increases germination percent but enhances productivity per se. With this background, the present study was undertaken to understand the reproductive morphology, pollen availability and effect of exogenous application of chemicals for enhancement of seed to ovule ratio in C. fulvus
Design and Simulation of Extended Interaction Cavities for a Ka band Multi beam Klystron
This article reports about the design approach, electromagnetic simulation and analysis results of high-frequency ladder-type input, output, and intermediate RF cavaties for Ka-band multi-beam extended interaction klystron. Several parameters of the cavity, such as quality factor, shunt impedance, etc., have been investigated by the assistance of electromagnetic software CST microwave studio
Efficacy of Different Herbicides on Weed Flora of Berseem (\u3cem\u3eTrifolium alexandrium L.\u3c/em\u3e)
Berseem is one of the prominent winter legume fodder crops. It has 20-24% crude protein and 70% digestible dry matter. Common weeds found in berseem are Cichorium intybus, Cornopus didimus, Spergula arvensis, Chenopodium album, Rumex dentatus and some grass family weeds. Weeds compete with main crop for essential plant nutrients, light, moisture and space. They not only deteriorate fodder quality but also decrease fodder and seed yield. Weed infestation reduces normally 25-35% green fodder and seed yield. It is the major challenge to control the berseem weeds for enhancement of productivity and quality of fodder and seed yield. Hence the present investigation is undertaken to study the efficacy of some herbicides for berseem weed management
Large magnetoelectric coupling in nanoscale BiFeO from direct electrical measurements
We report the results of direct measurement of remanent hysteresis loops on
nanochains of BiFeO at room temperature under zero and 20 kOe
magnetic field. We noticed a suppression of remanent polarization by nearly
40\% under the magnetic field. The powder neutron diffraction data reveal
significant ion displacements under a magnetic field which seems to be the
origin of the suppression of polarization. The isolated nanoparticles,
comprising the chains, exhibit evolution of ferroelectric domains under dc
electric field and complete 180 switching in switching-spectroscopy
piezoresponse force microscopy. They also exhibit stronger ferromagnetism with
nearly an order of magnitude higher saturation magnetization than that of the
bulk sample. These results show that the nanoscale BiFeO exhibits
coexistence of ferroelectric and ferromagnetic order and a strong
magnetoelectric multiferroic coupling at room temperature comparable to what
some of the type-II multiferroics show at a very low temperature.Comment: 7 pages with 5 figures, published in Phys. Rev.
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