2,667 research outputs found
Integrated campaign for aerosols, gases and radiation budget (ICARB): an overview
During March-May 2006, an extensive, multi-institution, multi-instrument, and multi-platform integrated field experiment 'Integrated Campaign for Aerosols, gases and Radiation Budget' (ICARB) was carried out under the Geosphere Biosphere Programme of the Indian Space Research Organization (ISRO-GBP). The objective of this largest and most exhaustive field campaign, ever conducted in the Indian region, was to characterize the physico-chemical properties and radiative effects of atmospheric aerosols and trace gases over the Indian landmass and the adjoining oceanic regions of the Arabian Sea, northern Indian Ocean, and Bay of Bengal through intensive, simultaneous observations. A network of ground-based observatories (over the mainland and islands), a dedicated ship cruise over the oceanic regions using a fully equipped research vessel, the Sagar Kanya, and altitude profiling over selected regions using an instrumented aircraft and balloonsondes formed the three segments of this integrated experiment, which were carried out in tandem. This paper presents an overview of the ICARB field experiment, the database generated, and some of its interesting outcomes though these are preliminary in nature. The ICARB has revealed significant spatio-temporal heterogeneity in most of the aerosol characteristics both over land and ocean. Observed aerosol loading and optical depths were comparable to or in certain regions, a little lower than those reported in some of the earlier campaigns for these regions. The preliminary results indicate: - low (< 0.2) aerosol optical depths (AOD) over most part of the Arabian Sea, except two pockets; one off Mangalore and the other, less intense, in the central Arabian Sea at ~18°N latitude - High Angstrom exponent in the southern Arabian Sea signifying steep AOD spectra and higher abundance of accumulation mode particles in the southern Arabian Sea and off Mangalore - Remarkably low Angstrom exponents signifying increased concentration of coarse mode aerosols and high columnar abundance in the northern Arabian Sea - Altitude profiles from aircraft showed a steady BC level up to 3 km altitude with structures which were associated with inversions in the atmospheric boundary layer (ABL) - A surprisingly large increase in the BC mass fraction with altitude - Presence of a convectively mixed layer extending up to about 1 km over the Arabian Sea and Bay of Bengal - A spatial off shore extent of < 100 km for the anthropogenic impact at the coast; and - Advection of aerosols, through airmass trajectories, from west Asia and NW arid regions of India leading to formation of elevated aerosol layers extending as far as 400 km off the east coast
A quantum exactly solvable non-linear oscillator related with the isotonic oscillator
A nonpolynomial one-dimensional quantum potential representing an oscillator,
that can be considered as placed in the middle between the harmonic oscillator
and the isotonic oscillator (harmonic oscillator with a centripetal barrier),
is studied. First the general case, that depends of a parameter , is
considered and then a particular case is studied with great detail. It is
proven that it is Schr\"odinger solvable and then the wave functions
and the energies of the bound states are explicitly obtained. Finally it
is proven that the solutions determine a family of orthogonal polynomials
related with the Hermite polynomials and such that: (i) Every
is a linear combination of three Hermite polynomials, and (ii)
They are orthogonal with respect to a new measure obtained by modifying the
classic Hermite measure.Comment: 11 pages, 11 figure
Semiclassical wave equation and exactness of the WKB method
The exactness of the semiclassical method for three-dimensional problems in
quantum mechanics is analyzed. The wave equation appropriate in the
quasiclassical region is derived. It is shown that application of the standard
leading-order WKB quantization condition to this equation reproduces exact
energy eigenvalues for all solvable spherically symmetric potentials.Comment: 13 page
Effect of isospin dependent cross-section on fragment production in the collision of charge asymmetric nuclei
To understand the role of isospin effects on fragmentation due to the
collisions of charge asymmetric nuclei, we have performed a complete
systematical study using isospin dependent quantum molecular dynamics model.
Here simulations have been carried out for , where n
varies from 47 to 59 and for , where m varies from 14
to 23. Our study shows that isospin dependent cross-section shows its influence
on fragmentation in the collision of neutron rich nuclei
Thermal Radiation from Au + Au Collisions at \sqrt{s} = 200 GEV/A Energy
The transverse momentum distribution of the direct photons measured by the
PHENIX collaboration in collisions at GeV/A has been
analyzed. It has been shown that the data can be reproduced reasonably well
assuming a deconfined state of thermalized quarks and gluons with initial
temperature more than the transition temperature for deconfinement inferred
from lattice QCD. The value of the initial temperature depends on the equation
of state of the evolving matter. The sensitivities of the results on various
input parameters have been studied. The effects of the modifications of
hadronic properties at non-zero temperature have been discussed.Comment: minor modifications in the text, accepted for publicatio
Resonant enhancement of the zero-phonon emission from a color center in a diamond cavity
We demonstrate coupling of the zero-phonon line of individual
nitrogen-vacancy centers and the modes of microring resonators fabricated in
single-crystal diamond. A zero-phonon line enhancement exceeding ten-fold is
estimated from lifetime measurements at cryogenic temperatures. The devices are
fabricated using standard semiconductor techniques and off-the-shelf materials,
thus enabling integrated diamond photonics.Comment: 5 pages, 4 figure
The systematic study of the influence of neutron excess on the fusion cross sections using different proximity-type potentials
Using different types of proximity potentials, we have examined the trend of
variations of barrier characteristics (barrier height and its position) as well
as fusion cross sections for 50 isotopic systems including various collisions
of C, O, Mg, Si, S, Ca, Ar, Ti and Ni nuclei with condition
for compound systems. The results of our studies reveal that the relationships
between increase of barrier positions and decrease of barrier heights are both
linear with increase of ratio. Moreover, fusion cross sections also
enhance linearly with increase of this ratio.Comment: 28 pages, 7 figures, 5 Table
Tensor Coupling and Vector Mesons in Dense Nuclear Matter
The effects of magnetic interaction between vector mesons and nucleons on the
propagation (mass and width) of the -meson in particular moving through
very dense nuclear matter is studied and the modifications, qualitative and
quantitative, due to the relevant collective modes (zero-sound and plasma
frequencies) of the medium discussed. It is shown that the -mesons
produced in high-energy nuclear collisions will be longitudinally polarized in
the region of sufficiently dense nuclear matter, in the presence of such an
interaction.Comment: Plain Latex file. Three figures, not appended, may be obtained on
request to [email protected]
On the Path Integral in Imaginary Lobachevsky Space
The path integral on the single-sheeted hyperboloid, i.e.\ in -dimensional
imaginary Lobachevsky space, is evaluated. A potential problem which we call
``Kepler-problem'', and the case of a constant magnetic field are also
discussed.Comment: 16 pages, LATEX, DESY 93-14
Any l-state improved quasi-exact analytical solutions of the spatially dependent mass Klein-Gordon equation for the scalar and vector Hulthen potentials
We present a new approximation scheme for the centrifugal term to obtain a
quasi-exact analytical bound state solutions within the framework of the
position-dependent effective mass radial Klein-Gordon equation with the scalar
and vector Hulth\'{e}n potentials in any arbitrary dimension and orbital
angular momentum quantum numbers The Nikiforov-Uvarov (NU) method is used
in the calculations. The relativistic real energy levels and corresponding
eigenfunctions for the bound states with different screening parameters have
been given in a closed form. It is found that the solutions in the case of
constant mass and in the case of s-wave () are identical with the ones
obtained in literature.Comment: 25 pages, 1 figur
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