35,764 research outputs found
A Distributed Parameters Model for Solar Cells
Distributive circuit element model for solar cells with series and shunt path
Magneto-Spectral Studies on Some Trivalent Metal Complexes: Chromium, Iron and Cobalt Complexes Derived from 4-Benzylamidothiosemicarbazide and its Thiosemicarbazone.
Complexes of chromium(Ill), iron(lll) and cobalt(III) with
4-benzy lamidothiosemicarbazide (BTSC) and 1-( a-)fury 1-4-benzy lamidothiosemicarbazone
(FBTS) have been prepared and characterized
by conventional chemical and physical measurements. Tetragonal
symmetry has been proposed for these complexes on the
basis of electronic spectral data. The various ligand field pp.rameteres
have been evaluated, wherever possible. The infrared spectral
studies indicate the S-N- bidentate nature of both ligands
Magneto-Spectral Studies on Some Trivalent Metal Complexes: Chromium, Iron and Cobalt Complexes Derived from 4-Benzylamidothiosemicarbazide and its Thiosemicarbazone.
Complexes of chromium(Ill), iron(lll) and cobalt(III) with
4-benzy lamidothiosemicarbazide (BTSC) and 1-( a-)fury 1-4-benzy lamidothiosemicarbazone
(FBTS) have been prepared and characterized
by conventional chemical and physical measurements. Tetragonal
symmetry has been proposed for these complexes on the
basis of electronic spectral data. The various ligand field pp.rameteres
have been evaluated, wherever possible. The infrared spectral
studies indicate the S-N- bidentate nature of both ligands
Adaptation dynamics of the quasispecies model
We study the adaptation dynamics of an initially maladapted population
evolving via the elementary processes of mutation and selection. The evolution
occurs on rugged fitness landscapes which are defined on the multi-dimensional
genotypic space and have many local peaks separated by low fitness valleys. We
mainly focus on the Eigen's model that describes the deterministic dynamics of
an infinite number of self-replicating molecules. In the stationary state, for
small mutation rates such a population forms a {\it quasispecies} which
consists of the fittest genotype and its closely related mutants. The
quasispecies dynamics on rugged fitness landscape follow a punctuated (or
step-like) pattern in which a population jumps from a low fitness peak to a
higher one, stays there for a considerable time before shifting the peak again
and eventually reaches the global maximum of the fitness landscape. We
calculate exactly several properties of this dynamical process within a
simplified version of the quasispecies model.Comment: Proceedings of Statphys conference at IIT Guwahati, to be published
in Praman
Resonant tunneling in fractional quantum Hall effect: superperiods and braiding statistics
We study theoretically resonant tunneling of composite fermions through their
quasi-bound states around a fractional quantum Hall island, and find a rich set
of possible transitions of the island state as a function of the magnetic field
or the backgate voltage. These considerations have possible relevance to a
recent experimental study, and bring out many subtleties involved in deducing
fractional braiding statistics.Comment: Phys. Rev. Lett. in pres
Weak lensing with COMBO-17: estimation and removal of intrinsic alignments
We estimate and remove the contamination of weak gravitational lensing
measurements by the intrinsic alignment of close pairs of galaxies. We do this
by investigating both the aperture mass B mode statistic, and the shear
correlations of close and distant pairs of galaxies. We re-analyse the COMBO-17
survey, and study published results from the RCS and the VIRMOS-DESCART survey,
concluding that the intrinsic alignment effect is at the lower end of the range
of theoretical predictions. We also revisit this theoretical issue, and show
that misalignment of baryon and halo angular momenta may be an important effect
which can reduce the intrinsic ellipticity correlations estimated from
numerical simulations to the level that we and the SuperCOSMOS survey observe.
We re-examine the cosmological parameter estimation from the COMBO-17 survey,
now marginalising over the Hubble constant. Assuming no evolution in galaxy
clustering, and marginalising over the intrinsic alignment signal, we find the
mass clustering amplitude is reduced by 0.03 to sigma_8(Omega_m / 0.27)^0.6 =
0.71 +/- 0.11. We consider the forthcoming SNAP wide weak lensing survey, and
the CFHTLS wide synoptic survey, and expect them to be contaminated on scales
>1 arcmin by intrinsic alignments at the level of ~1% and ~2% respectively.
Division of the SNAP survey for lensing tomography significantly increases the
contamination in the lowest redshift bin to ~7% and possibly higher. Removal of
the intrinsic alignment effect by the downweighting of nearby galaxy pairs will
therefore be vital for SNAP, (abridged).Comment: Accepted for publication in MNRAS, 15 pages, 18 figure
Breadboard stellar tracker system test report, volume 1
The performance of a star tracker equipped with a focal plane detector was evaluated. The CID board is an array of 256 x 256 pixels which are 20 x 20 micrometers in dimension. The tracker used for test was a breadboard tracker system developed by BASD. Unique acquisition and tracking algorithms are employed to enhance performance. A pattern recognition process is used to test for proper image spread function and to avoid false acquisition on noise. A very linear, high gain, interpixel transfer function is derived for interpolating star position. The lens used in the tracker has an EFL of 100 mm. The tracker has an FOV of 2.93 degrees resulting in a pixel angular subtense of 41.253 arc sec in each axis. The test procedure used for the program presented a star to the tracker in a circular pattern of positions; the pattern was formed by projecting a simulated star through a rotatable deviation wedge. Further tests determined readout noise, Noise Equivalent Displacement during track, and spatial noise during acquisition by taking related data and reducing it
Microscopic origin of the next generation fractional quantum Hall effect
Most of the fractions observed to date belong to the sequences and , and integers, understood as the familiar
{\em integral} quantum Hall effect of composite fermions. These sequences fail
to accommodate, however, many fractions such as and 5/13, discovered
recently in ultra-high mobility samples at very low temperatures. We show that
these "next generation" fractional quantum Hall states are accurately described
as the {\em fractional} quantum Hall effect of composite fermions
Solar cycle induced variations in GONG p-mode frequencies and splittings
We have analysed the recently available GONG p-mode frequencies and splitting
coefficients for a period of three and half years, including the rapidly rising
phase of solar cycle 23. The analysis of mean frequency shift with different
activity indices shows that the shift is equally correlated with both magnetic
and radiative indices. During the onset of the new cycle 23, we notice that the
change in splitting coefficient is more prominent than the change in
. We have estimated the solar rotation rate with varying depth and
latitude. In the equatorial region, the rotation first increases with depth and
then decreases, while an opposite behaviour is seen in the polar region. We
also find a small but significant temporal variation in the rotation rate at
high latitudes.Comment: Uses aastex, To appear in Astrophysical Journal, October 10, 2000
issu
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