506 research outputs found
Anisotropic Hubbard model on a triangular lattice -- spin dynamics in Ho Mn O_3
The recent neutron-scattering data for spin-wave dispersion in are well described by an anisotropic Hubbard model on a triangular lattice
with a planar (XY) spin anisotropy. Best fit indicates that magnetic
excitations in correspond to the strong-coupling limit , with planar exchange energy meV and planar
anisotropy meV.Comment: 4 pages, 3 figure
CORRELATION OF NUTRITIONAL STATUS OF MOTHER AND THE BIRTH WEIGHT OF THE BABY
Objective: The objective of this study is to correlate mother's nutritional status during pregnancy and determine the birth weight of the baby.Methods: A comparative, exploratory approach and prospective cohort study design was used to find out mothers' nutritional status during pregnancy influences the birth weight of babies. The data were collected using structured interview schedule and dietary history by 24 h recall method from a randomly selected sample of 380 eligible mothers delivered at Krishna Hospital, Karad.Results: There was a significant correlation between birth weight and calorie intake (correlation coefficient [r]=0.595; p<0.001; Chi-square=201.3; p<0.001.) A higher proportion of low birth weight babies, i.e., 105 (32.2%) were delivered by the mothers consuming <70% of protein ([r]=0.245; p<0.001; χ2=24.033; p<0.001]). There was correlation between birth weight and calcium intake of mothers ([r]=0.525; p<0.001; χ2=10.12; p<0.001] birth†weight and iron intake of mothers ([r]=0.250; p<0.001; χ2=13.798; p<0.001).Conclusion: The intake of calorie, protein, calcium, and iron of mother can significantly influence the weight of the newborn baby. Among all anthropometric parameters of the mother, weight gain was the strongest predictor of adequacy of the birth weight
Testing and Modeling Electrical Characteristics of Novel Silicon Carbide (SiC) Static Induction Transistors (SITs)
Negaton and Positon Solutions of the KDV Equation
We give a systematic classification and a detailed discussion of the
structure, motion and scattering of the recently discovered negaton and positon
solutions of the Korteweg-de Vries equation. There are two distinct types of
negaton solutions which we label and , where is the
order of the Wronskian used in the derivation. For negatons, the number of
singularities and zeros is finite and they show very interesting time
dependence. The general motion is in the positive direction, except for
certain negatons which exhibit one oscillation around the origin. In contrast,
there is just one type of positon solution, which we label . For
positons, one gets a finite number of singularities for odd, but an
infinite number for even values of . The general motion of positons is in
the negative direction with periodic oscillations. Negatons and positons
retain their identities in a scattering process and their phase shifts are
discussed. We obtain a simple explanation of all phase shifts by generalizing
the notions of ``mass" and ``center of mass" to singular solutions. Finally, it
is shown that negaton and positon solutions of the KdV equation can be used to
obtain corresponding new solutions of the modified KdV equation.Comment: 20 pages plus 12 figures(available from authors on request),Latex
fil
Axisymmetric equilibria of a gravitating plasma with incompressible flows
It is found that the ideal magnetohydrodynamic equilibrium of an axisymmetric
gravitating magnetically confined plasma with incompressible flows is governed
by a second-order elliptic differential equation for the poloidal magnetic flux
function containing five flux functions coupled with a Poisson equation for the
gravitation potential, and an algebraic relation for the pressure. This set of
equations is amenable to analytic solutions. As an application, the
magnetic-dipole static axisymmetric equilibria with vanishing poloidal plasma
currents derived recently by Krasheninnikov, Catto, and Hazeltine [Phys. Rev.
Lett. {\bf 82}, 2689 (1999)] are extended to plasmas with finite poloidal
currents, subject to gravitating forces from a massive body (a star or black
hole) and inertial forces due to incompressible sheared flows. Explicit
solutions are obtained in two regimes: (a) in the low-energy regime
, where
, , , and are related to the thermal,
poloidal-current, flow and gravitating energies normalized to the
poloidal-magnetic-field energy, respectively, and (b) in the high-energy regime
. It turns out
that in the high-energy regime all four forces, pressure-gradient,
toroidal-magnetic-field, inertial, and gravitating contribute equally to the
formation of magnetic surfaces very extended and localized about the symmetry
plane such that the resulting equilibria resemble the accretion disks in
astrophysics.Comment: 12 pages, latex, to be published in Geophys. Astrophys. Fluid
Dynamic
Bosonization of non-relativstic fermions in 2-dimensions and collective field theory
We revisit bosonization of non-relativistic fermions in one space dimension.
Our motivation is the recent work on bubbling half-BPS geometries by Lin, Lunin
and Maldacena (hep-th/0409174). After reviewing earlier work on exact
bosonization in terms of a noncommutative theory, we derive an action for the
collective field which lives on the droplet boundaries in the classical limit.
Our action is manifestly invariant under time-dependent reparametrizations of
the boundary. We show that, in an appropriate gauge, the classical collective
field equations imply that each point on the boundary satisfies Hamilton's
equations for a classical particle in the appropriate potential. For the
harmonic oscillator potential, a straightforward quantization of this action
can be carried out exactly for any boundary profile. For a finite number of
fermions, the quantum collective field theory does not reproduce the results of
the exact noncommutative bosonization, while the latter are in complete
agreement with the results computed directly in the fermi theory.Comment: references added and typos corrected; 21 pages, 3 figures, eps
On Some Classes of mKdV Periodic Solutions
We obtain exact periodic solutions of the positive and negative modified
Kortweg-de Vries (mKdV) equations. We examine the dynamical stability of these
solitary wave lattices through direct numerical simulations. While the positive
mKdV breather lattice solutions are found to be unstable, the two-soliton
lattice solution of the same equation is found to be stable. Similarly, a
negative mKdV lattice solution is found to be stable. We also touch upon the
implications of these results for the KdV equation.Comment: 8 pages, 3 figures, to appear in J. Phys.
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