Protection against Radiation Induced Performance Decrement in Mice

Recognising that there is lack of information on the effects of low-level ionizing radiations and the modifying role of radioprotectors, an attempt has been made in this study to explore the relationship between impairment of spatial learning and low level of radiation exposure. A radial arm maze was utilised to evaluate radiation-induced behavioural alterations and performance decrement in mice. Immediately after whole body exposure to gamma radiation (absorbed dose, I Gy) significant perturbations in the learned behaviour of the animals were observed. The regular control movement became irregular and the food consumption time was reduced appreciably (40 %). Recovery took place in four days. If diltiazem (7 mg/kg b.w.), a Ca/sup 2+/ channel blocker and a radioprotector, was administered i.p. 20-30 min prior to irradiation, radiation-induced behavioural abnormalities were reduced. Mechanisms underlying protection by diltiazem against radiation-induced performance decrement observed in the present study need to be investigated

Composite fermions traversing a potential barrier

Using a composite fermion picture, we study the lateral transport between two two-dimensional electron gases, at filling factor 1/2, separated by a potential barrier. In the mean field approximation, composite fermions far from the barrier do not feel a magnetic field while in the barrier region the effective magnetic field is different from zero. This produces a cutoff in the conductance when represented as a function of the thickness and height of the barrier. There is a range of barrier heights for which an incompressible liquid, at $\nu =1/3$, exists in the barrier region.Comment: 3 pages, latex, 4 figures available upon request from [email protected]. To appear in Physical Review B (RC) June 15t

Systematics of Anti magnetic rotation in even-even Cd isotopes

The lifetimes for the high spin levels of the yrast band of $^{110}$Cd has been measured. The estimated B(E2) values decrease with increase in angular momentum. This is the characteristic of Anti magnetic rotation as reported in $^{106,108}$Cd. However, alignment behavior of $^{110}$Cd is completely different from its even-even neighbors. A model based on classical particle plus rotor has been used to explore the underlying systematics and develop a self consistent picture for the observed behavior of these isotopes.Comment: 18 pages including 6 figures. Accepted to be published in PLB, with some modification in the tex

Projected shell model study for the yrast-band structure of the proton-rich mass-80 nuclei

A systematic study of the yrast-band structure for the proton-rich, even-even mass-80 nuclei is carried out using projected shell model approach. We describe the the energy spectra, transition quadrupole moments and gyromagnetic factors. The observed variations in energy spectra and transition quadrupole moments in this mass region are discussed in terms of the configuration mixing of the projected deformed Nilsson states as a function of shell filling.Comment: 22 pages, 7 figure

On the fourth-order accurate compact ADI scheme for solving the unsteady Nonlinear Coupled Burgers' Equations

The two-dimensional unsteady coupled Burgers' equations with moderate to severe gradients, are solved numerically using higher-order accurate finite difference schemes; namely the fourth-order accurate compact ADI scheme, and the fourth-order accurate Du Fort Frankel scheme. The question of numerical stability and convergence are presented. Comparisons are made between the present schemes in terms of accuracy and computational efficiency for solving problems with severe internal and boundary gradients. The present study shows that the fourth-order compact ADI scheme is stable and efficient

Pulsed Magnetic Field Measurements of the Composite Fermion Effective Mass

Magnetotransport measurements of Composite Fermions (CF) are reported in 50 T pulsed magnetic fields. The CF effective mass is found to increase approximately linearly with the effective field $B^*$, in agreement with our earlier work at lower fields. For a $B^*$ of 14 T it reaches $1.6m_e$, over 20 times the band edge electron mass. Data from all fractions are unified by the single parameter $B^*$ for all the samples studied over a wide range of electron densities. The energy gap is found to increase like $\sqrt{B^*}$ at high fields.Comment: Has final table, will LaTeX without error

Quantum railroads and directed localization at the juncture of quantum Hall systems

The integer quantum Hall effect (QHE) and one-dimensional Anderson localization (AL) are limiting special cases of a more general phenomenon, directed localization (DL), predicted to occur in disordered one-dimensional wave guides called "quantum railroads" (QRR). Here we explain the surprising results of recent measurements by Kang et al. [Nature 403, 59 (2000)] of electron transfer between edges of two-dimensional electron systems and identify experimental evidence of QRR's in the general, but until now entirely theoretical, DL regime that unifies the QHE and AL. We propose direct experimental tests of our theory.Comment: 11 pages revtex + 3 jpeg figures, to appear in Phys. Rev.

Spectral Dependence of Polarized Radiation due to Spatial Correlations

We study the polarization of light emitted by spatially correlated sources. We show that in general polarization acquires nontrivial spectral dependence due to spatial correlations. The spectral dependence is found to be absent only for a special class of sources where the correlation length scales as the wavelength of light. We further study the cross correlations between two spatially distinct points that are generated due to propagation. It is found that such cross correlation leads to sufficiently strong spectral dependence of polarization which can be measured experimentally.Comment: 5 pages, 4 figure

Instability of the rhodium magnetic moment as origin of the metamagnetic phase transition in alpha-FeRh

Based on ab initio total energy calculations we show that two magnetic states of rhodium atoms together with competing ferromagnetic and antiferromagnetic exchange interactions are responsible for a temperature induced metamagnetic phase transition, which experimentally is observed for stoichiometric alpha-FeRh. A first-principle spin-based model allows to reproduce this first-order metamagnetic transition by means of Monte Carlo simulations. Further inclusion of spacial variation of exchange parameters leads to a realistic description of the experimental magneto-volume effects in alpha-FeRh.Comment: 10 pages, 13 figures, accepted for publication in Phys. Rev.