Minimum audible angle thresholds obtained under conditions in which the precedence effect is assumed to operate

Two experiments were conducted to examine the ability of human listeners to localize the "lag" or "echo" source in a precedence effect paradigm. A 5-ms noise burst was presented from a source located between 554-279 cm from the subject. This "lead" source was always located at 0 degrees azimuth. At the same time, one of two sources located at a distance of 610 cm from the subject was also activated with the same 5-ms noise burst. The subject's task was to identify which lag source had been active. Across sessions, the angular distance between the lag sources was varied, so as to allow a determination of the minimum audible angle (MAA) that could be resolved. Tests were run in a room designed to minimize reflections and in a hallway that was acoustically quite complex. No systematic differences in MAA thresholds were observed as a function of the environment employed. MAA thresholds obtained without the signal from the lead speaker were less than 1 degree for four of the five subjects tested. The precedence effect, as measured by the change in the MAA threshold, appears to have only a modest influence on localization performance. Under conditions in which the lead source was concurrently active, the thresholds were generally elevated by only 2 degrees-4 degrees. A reduction of this magnitude in the ability to resolve the position of the lag source does not seem to be sufficient, in itself, to account for the excellent localization performance frequently observed in reflective environments.     

Breakdown of echo suppression in the precedence effect

A new phenomenon is reported in which a change in spatial location of the leading sound source disrupts the normal echo suppression of the precedence effect. Click trains were presented through two loudspeakers, one leading the other by a few milliseconds. When leading and lagging signals were switched, listeners heard clicks momentarily for as long as several seconds from both loudspeakers before echo suppression was reestablished.     

True atomic resolution under ambient conditions obtained by atomic force microscopy in the contact mode

2 ) has been investigated by contact-mode atomic force microscopy (AFM) in air. Both the terraces and the monolayer step itself were reproducibly imaged at atomic resolution in the repulsive-force regime at forces between tip apex and sample of the order of 10^-9 N. Several kinks were also imaged at atomic resolution. Details of the atomic registry of subsequent Se-Nb-Se sandwich layers as well as the arrangement of the individual atoms at the kink sites were resolved. The results are in perfect quantitative agreement with the lattice structure known from X-ray analysis and indicate that true atom-by-atom lateral resolution of microscopic defects is feasible by AFM in the contact mode and under ambient conditions. Published online: 10 February 1999     

Spin-wave resonance in magnetic films under conditions of the skin effect

The spin-wave resonance spectrum of a ferromagnetic film magnetized normally to its surface is investigated as a function of the finite depth of penetration of the high-frequency field into the film with due regard for damping in the spin system and different types of surface-spin pinning. The exact numerical solution of the equation of motion for magnetization is obtained by considering the finite thickness of the skin layer. For a substantially inhomogeneous distribution of the high-frequency field over the layer thickness, the change in the resonance shape at frequencies close to the ferromagnetic resonance frequency is observed in addition to the broadening of all the resonance peaks and the decrease in their amplitudes.     

Spin Hall effect in nonmagnetic conductors under the classical Hall conditions

The spin Hall effect—the excitation of a spin flux by an electric current normal to it—is considered in a paramagnetic sample in disregard of the spin-orbit coupling in the classical Hall effect case, when the Pauli spin polarization is induced by the magnetic field H ₀ normal to the electric current.     

Skin effect under the conditions of ferromagnetic and spin-wave resonance

An expression for the electromagnetic field penetration depth in a metallic magnetic layer is derived taking into account the complexity of the high-frequency permeability under the conditions of ferromagnetic and spin-wave resonance. The frequency dependences of the skin depth and its dependences on the magnitude and type of spin pinning are determined from a numerical analysis of the solutions of the motion equation for magnetization. Some features of the dependences associated with the nature of the spin-wave spectrum are revealed.     

Compensation effect in undoped polycrystalline CdTe synthesized under nonequilibrium conditions

The compensation effect has been revealed in undoped polycrystalline CdTe synthesized during rapid crystallization. The revealed effect leads to an increase in the electrical resistivity to 10⁸–10¹⁰ Ω cm at a background impurity concentration of ～1015 cm^?3 (Ga_Cd and Cl_Te donors, unidentified acceptors). For some samples, this effect is accompanied by the appearance of persistent photoconductivity, which disappears at a temperature of ～200 K. It has been shown that all the polycrystals studied are characterized by a three-level compensation mechanism in which the fundamental properties of the material are determined by deep donors and/or acceptors with a concentration of 10¹² cm^?3. Depending on the specific growth conditions, the electrical resistivity at room temperature is determined by deep centers with activation energies of 0.59 ± 0.10 and 0.71 ± 0.10 eV, which are supposedly related to intrinsic point defects, and deep centers with activation energies of 0.4 ± 0.1 eV, which belong to the DX center formed by the Ga_Cd donor.     

Failure-delay effect in destruction of steel samples under spalling conditions

Dynamic spalling tests have been run on two batches of 30KhN4M steel samples. Experimental data have been processed with the classical technique based on solution of the elastic wave equation. Three samples have been revealed that demonstrated the failure-delay effect under testing. The incubation-time criterion has been used to show the conditions of emergence of failure delay with the example of triangular loading pulses. A rate strength curve has been constructed for the other samples. It has been shown that the limiting strengths under dynamic loads considerably differ for samples from different batches despite the same chemical composition and static strength.     

Aharonov-bohm effect on multiwall carbon nanotubes under conditions close to strong carrier localization

The Aharonov-Bohm effect on multiwall carbon nanotubes has been studied under conditions of resistance with decreasing temperature as an inverse power function, which precede strong carrier localization. A periodic contribution with a period of 18 T corresponding to the magnetic flux quantum ħc/e per nanotube cross section has been revealed in the longitudinal magnetoresistance. The result points to the possibility of the ballistic motion of the carriers over the sample perimeter under conditions close to their strong localization in the longitudinal direction.     

Electrocaloric effect in triglycine sulfate under equilibrium and nonequilibrium thermodynamic conditions

The direct and indirect measurements of intensive electrocaloric effect in a triglycine sulfate ferroelectric crystal are performed under equilibrium and nonequilibrium thermodynamic conditions implemented in the adiabatic calorimeter. The effect of the electric field parameters (frequency, profile, and strength) on the value of the effect and degree of its reversibility are studied. The difference between the temperature variation values in a switched-on and switched-off dc field under quasi-isothermal conditions is established. The low-frequency periodic electric field induces the temperature gradient along the electrocaloric element and heat flux from its free end to the thermostated base. A significant excess of the field switching-off rate over the switching-on rate leads to a noticeable intensification of the cooling effect.     

Photomagnetic effect under conditions of bipolar Hall-effect conductivity due to volume and surface excitation

A study was made concerning the Hall mobilities of electrons and holes as well as the photomagnetically measurable electron mobility in high-resistivity gallium arsenide doped with oxygen, over a wide range of intensities of radiation absorbed in the volume and at the surface. The feasibility of a reliable determination of electron and hole mobilities under conditions of strongly p- and n- bipolar Hall mobilities has been demonstrated experimentally.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No.2, pp.21–25, February, 1976.     

Spin relaxation under conditions of the quantum Hall effect with odd filling

The relaxation of spins in a completely polarized state such that the initial direction of polarization is different from the direction of the external magnetic field is studied. The relaxation mechanism is governed by the spin-orbit and electron-phonon interactions and involves the excitation of nonzero spin excitons. Pis’ma Zh. éksp. Teor. Fiz. 63, No. 1, 43–48 (10 January 1996)     

Giant fluctuations in the radiation intensity of two-dimensional electrons under quantum hall effect conditions

Giant fluctuations in the 2D-electron recombination radiation were studied in structures with a single or double GaAs quantum well under quantum Hall effect conditions. It is established that, if these conditions are exactly satisfied, the amplitude of the 2D-electron photoluminescence (PL) intensity is several orders of magnitude higher than the noise level, with the noise having a normal (Poisson) distribution. The fluctuations in the PL line intensity are accompanied by a jumpwise change in the line positions. Analogous jumps were also observed in the spectra of inelastic light scattering by 2D electrons in structures with a single GaAs quantum well. The fluctuation processes are correlated over macroscopic distances. The characteristic correlation length is 1–2 mm. The spectral density of giant fluctuations was found to exhibit narrow peaks. The ratios of the frequencies of these peaks are equal to those of Fibonacci numbers. The appearance of such frequencies in the fluctuation spectrum indicates that the fluctuations studied bear a resemblance to processes occurring in open dissipative dynamic systems. The methods developed in the theory of these systems can, in principle, be used to study giant fluctuations.     

Resonant tunneling effect in one-dimensional twinned lattice photonic crystal under total reflection conditions

Under total reflection conditions, it typically seems as though light waves will be reflected completely on the interface; in actuality, the waves can penetrate the medium as evanescent waves. In this paper, we present a twinned lattice photonic crystal with a unit cell composed of AB layers and their mirror. We assume that the refractive index n ₀ of the input and output end is equal to n _B and larger than n _A . We first demonstrate the dependence of band structure on the incidence angle and normalized wavelength, in which the resonant tunneling bands are exposed. We then draw a comparison of bands between ABBA and AB. To conclude, we discuss the resonant tunneling effect in the twinned lattice photonic crystal under the total reflection conditions. As incidence angle increases, the resonant tunneling band ultimately vanishes completely.     

A model of the size effect in a ferroelectric thin film under conditions of the phase transition

The size effects observed in thin films of displacive ferroelectrics are considered. A model of the dependence of the spontaneous polarization and phase transition temperature on the film thickness is proposed.