Investigation of Shallow Sedimentary Structure of the Anchorage Basin, Alaska, Using Simulated Annealing Inversion of Site Response

This study deals with shallow sedimentary structure of the Anchorage basin in Alaska. For this purpose, inversion of site response [SR(f)] data in the frequency range 0.5-11.0 Hz from various sites of the basin has been performed using the simulated annealing method to compute subsurface layer thickness, shear-wave velocity (beta), density, and shear-wave quality factor. The one-dimensional (1D) models for the aforementioned parameters were obtained with preset bounds on the basis of available geological information such that the L-2 norm error between the observed and computed site response attained a global minimum. Next, the spatial distribution of the important parameter beta was obtained by interpolating values yielded by the 1D models. The results indicate the presence of three distinct velocity zones as the source of spatial variation of SR(f) in the Anchorage basin. In the uppermost part of the basin, the beta values of fine-grain Quaternary sediments mainly lie in the range of 180-500 m/sec with thickness varying from 15 to 50 m. This formation overlies relatively thick (80-200 m) coarse-grain Quaternary sediments with beta values in the range of 600-900 m/sec. These two Quaternary units are, in turn, overlain on Tertiary sediments with beta > 1000 m/sec located at depths of 100 and 250 m, respectively, in the central and western side along the Knik Arm parts of the basin. The important implication of the result is that the sources of spatial variation of SR(f) in the Anchorage basin for the frequency band 0.5-11 Hz, besides in the uppermost 30 m, are found to be deeper than this depth. Thus, use of commonly considered geological formations in the depth intervals from 0 to 30 m for the ground-motion interpretation will likely yield erroneous results in the Anchorage basin.GIEnvironment and Natural Resources InstituteSchool of Engineering of the University of Alaska, AnchorageGeological Science

Operator splitting for the Benjamin-Ono equation

In this paper we analyze operator splitting for the Benjamin-Ono equation, u_t = uu_x + Hu_xx, where H denotes the Hilbert transform. If the initial data are sufficiently regular, we show the convergence of both Godunov and Strang splitting.Comment: 18 Page

Understanding the Fano Resonance : through Toy Models

The Fano Resonance, involving the mixing between a quasi-bound `discrete' state of an inelastic channel lying in the continuum of scattering states belonging to the elastic channel, has several subtle features. The underlying ideas have recently attracted attention in connection with interference effects in quantum wires and mesoscopic transport phenomena. Simple toy models are provided in the present study to illustrate the basics of the Fano resonance in a simple and tractable setting.Comment: 17 pages, 1 figur

Adiabatic multicritical quantum quenches: Continuously varying exponents depending on the direction of quenching

We study adiabatic quantum quenches across a quantum multicritical point (MCP) using a quenching scheme that enables the system to hit the MCP along different paths. We show that the power-law scaling of the defect density with the rate of driving depends non-trivially on the path, i.e., the exponent varies continuously with the parameter $\alpha$ that defines the path, up to a critical value $\alpha= \alpha_c$; on the other hand for $\alpha \geq \alpha_c$, the scaling exponent saturates to a constant value. We show that dynamically generated and {\it path($\alpha$)-dependent} effective critical exponents associated with the quasicritical points lying close to the MCP (on the ferromagnetic side), where the energy-gap is minimum, lead to this continuously varying exponent. The scaling relations are established using the integrable transverse XY spin chain and generalized to a MCP associated with a $d$-dimensional quantum many-body systems (not reducible to two-level systems) using adiabatic perturbation theory. We also calculate the effective {\it path-dependent} dimensional shift $d_0(\alpha)$ (or the shift in center of the impulse region) that appears in the scaling relation for special paths lying entirely in the paramagnetic phase. Numerically obtained results are in good agreement with analytical predictions.Comment: 5 pages, 4 figure

Horava-Lifshitz modifications of the Casimir effect

We study the modifications induced by spacetime anisotropy on the Casimir effect in the case of two parallel plates. Nonperturbative and perturbative regimes are analyzed. In the first case the Casimir force either vanishes or it reverses its direction which, in any case, makes the proposal untenable. On the other hand, the perturbative model enables us to incorporate appropriately the effects of spacetime anisotropy.Comment: 6 pages, revtex

HELMINTHIASIS IN A BENGAL TIGER (PANTHERA TIGRIS TIGRIS) - A CASE REPORT

During post mortem examination of a wild male adult Bengal Tiger of Pirkhali of Sundarban Tiger Reserve, West Bengal, India,Toxocara cati and Taenia hydatigena was observed in the stomach and intestine

Defect generation in a spin-1/2 transverse XY chain under repeated quenching of the transverse field

We study the quenching dynamics of a one-dimensional spin-1/2 $XY$ model in a transverse field when the transverse field $h(=t/\tau)$ is quenched repeatedly between $-\infty$ and $+\infty$. A single passage from $h \to - \infty$ to $h \to +\infty$ or the other way around is referred to as a half-period of quenching. For an even number of half-periods, the transverse field is brought back to the initial value of $-\infty$; in the case of an odd number of half-periods, the dynamics is stopped at $h \to +\infty$. The density of defects produced due to the non-adiabatic transitions is calculated by mapping the many-particle system to an equivalent Landau-Zener problem and is generally found to vary as $1/\sqrt{\tau}$ for large $\tau$; however, the magnitude is found to depend on the number of half-periods of quenching. For two successive half-periods, the defect density is found to decrease in comparison to a single half-period, suggesting the existence of a corrective mechanism in the reverse path. A similar behavior of the density of defects and the local entropy is observed for repeated quenching. The defect density decays as $1/{\sqrt\tau}$ for large $\tau$ for any number of half-periods, and shows a increase in kink density for small $\tau$ for an even number; the entropy shows qualitatively the same behavior for any number of half-periods. The probability of non-adiabatic transitions and the local entropy saturate to 1/2 and $\ln 2$, respectively, for a large number of repeated quenching.Comment: 5 pages, 3 figure

Steps on current-voltage characteristics of a silicon quantum dot covered by natural oxide

Considering a double-barrier structure formed by a silicon quantum dot covered by natural oxide with two metallic terminals, we derive simple conditions for a step-like voltage-current curve. Due to standard chemical properties, doping phosphorus atoms located in a certain domain of the dot form geometrically parallel current channels. The height of the current step typically equals to (1.2 pA)N, where N=0,1,2,3... is the number of doping atoms inside the domain, and only negligibly depends on the actual position of the dopants. The found conditions are feasible in experimentally available structures.Comment: 4 pages, 3 figure