Optical properties of AlxGa1−xAs/GaAs Woods–Saxon quantum well in the presence of hydrostatic pressure and applied electric field

The third harmonic generation (THG), linear and nonlinear optical absorption coefficients (OACs), and refractive index changes (RICs) are investigated in a Woods–Saxon quantum well (QW) modulated by the hydrostatic pressure and applied electric field. The effect of non-uniform aluminum doping (position-dependent effective mass (PDEM)) on the mass of the system is discussed, and further to explore the influence of PDEM on the nonlinear THG, OACs, and RICs of the Woods–Saxon QW. These nonlinear optical properties above are obtained using the compact-density matrix formalism. The electron states in a Woods–Saxon QW under the constant effective mass (CEM) and PDEM are calculated by solving the Schrödinger equation via the finite difference technique. The contributions from competing effects of the hydrostatic pressure and applied electric field to the nonlinear optical properties with CEM and PDEM are reported, as well as the comparison with each other. The observations reveal that the regulation of external fields and the influence of PDEM play an important role in the photoelectric properties of QW.     

静压下Znse／Zn_（1－x）Cd_xSe应变超晶格的光致发光研究

本文首次在室温和０—２．５ＧＰａ静压范围内研究了Ｚｎｓｅ／Ｚｎ０．２６Ｃｄ０．２６Ｓｅ应变超晶格的静压光致发光，观察到了室温条件下的超晶格阱层的重空穴激子跃迁随压力的亚线性变化的特性．经过计算机拟合实验数据得到了一阶和二阶压力系数．理论计算得到的一阶压力系数与实验得到的压力系数符合得较好。     

Depletion of arginine in yeast cells decreases the resistance to hydrostatic pressure

High hydrostatic pressure (HP) inhibits growth and inactivates microorganisms by destabilizing non-covalent molecular interactions. Arginine contributes to stress resistance because it has a guanidine side chain, which assists in the refolding of aggregated proteins. We attempted to analyze the contribution of arginine to high HP stress using a pressure-sensitive mutant strain of Saccharomyces cerevisiae and a metabolomics approach. Our results showed that the content of 136 out of 250 detected metabolites differed in the mutant and parent strains. Decreased metabolites were involved in the tricarboxylic acid cycle and arginine biosynthesis. The expression of genes contributing to arginine biosynthesis was significantly lower in the mutant strain than in the parent strain. When arginine was supplemented to the medium, the mutant strain showed more tolerance to pressure. These results suggest that yeast cells survived due to the contribution of arginine to high pressure resistance. This indicates that depletion of arginine caused by decreased activity of the biosynthesis pathway confers sensitivity to HP.     

Comparing analytical and numerical solution of nonlinear two and three‐dimensional hydrostatic flows

New test cases for frictionless, three‐dimensional hydrostatic flows have been derived from some known analytical solutions of the two‐dimensional shallow water equations. The flow domain is a paraboloid of revolution and the flow is determined by the initial conditions, the nonlinear advective terms, the Coriolis acceleration and by the hydrostatic pressure. Wetting and drying is also included. Some specific properties of the exact solutions are discussed under different hypothesis and relative importance of the forcing terms. These solutions are proposed for testing the stability, the accuracy and the efficiency of numerical models to be used for simulating environmental hydrostatic flows. The computed solutions obtained with a semi‐implicit finite difference—finite volume algorithm on unstructured grid are compared with the corresponding analytical solutions in both two and three space dimension. Excellent agreement are obtained for the velocity and for the resulting water surface elevation. Comparison of the computed inundation area also shows a good agreement with the analytical solution with degrading accuracy observed when the inundation area becomes relatively large and for long simulation time. Copyright © 2006 John Wiley & Sons, Ltd.     

Founding editor Dr Philip M. Gresho

A numerical technique is presented for the approximation of vertical gradient of the non‐hydrostatic pressure arising in the Reynolds‐averaged Navier–Stokes equations for simulating non‐hydrostatic free‐surface flows. It is based on the Keller‐box method that take into account the effect of non‐hydrostatic pressure with a very small number of vertical grid points. As a result, the proposed technique is capable of simulating relatively short wave propagation, where both frequency dispersion and non‐linear effects play an important role, in an accurate and efficient manner. Numerical examples are provided to illustrate this; accurate wave characteristics are already achieved with only two layers. Copyright © 2003 John Wiley & Sons, Ltd.     

The effect of pressure on galvanomagnetic properties of indium antimonide irradiated with electrons

Abstract

The galvanomagnetic properties of electron-irradiated n- and p-InSb under high hydrostatic pressure have been investigated. It has been shown that electron irradiation generates a series of deep levels split from the valence band.     

Heartbeat sensors under pressure: a new method for assessing hyperbaric physiology

Non-invasive heartbeat sensors to measure the cardiac activity of crustaceans have been adapted for use under hyperbaric conditions. Able to record data continuously over long timescales, these sensors can collect high-resolution data on the physiological state of an organism up to a tested limit of 300 atm. Using this technique, heart rate was recorded in a juvenile of the sublittoral spider crab, Maja brachydactyla (Decapoda: Majidae), when subjected to hydrostatic pressures of 1, 50, 100, and 150 atm for periods of 30 min. Heart rate increases with pressure until 100 atm (one-way repeated measures ANOVA: F _{(4, 25)}=154.76, p<0.001). However, the significant decrease in the mean heart rate from 137.07 bpm at 100 atm to 118.40 bpm at 150 atm (t-test: t=4.581, d.f.=10, p<0.001) indicates a mechanistic limit in the cardiac response of this species to pressures beyond 100 atm. This method could be potentially applied to any marine invertebrate with a neurogenic heart.     

Listeria monocytogenes cells injured by high hydrostatic pressure and their recovery in nutrient-rich or -free medium during cold storage

ABSTRACT

Cells of Listeria monocytogenes suspended in phosphate-buffered saline (PBS) were treated by high hydrostatic pressure (HHP; 500?MPa, 25°C, 10?min), diluted by ten folds using trypticase soy broth (TSB) or PBS, and stored at cold temperatures of 0–15°C. Viable cell count in TSB increased logarithmically close to the initial count at each storage temperature, while that in PBS increased temporarily and subsequently decreased to almost nondetectable level except the case at 15°C, where it showed logarithmic increase thereafter. Based on proliferation experiments where their healthy cells were inoculated to TSB or to PBS containing their heat-killed dead cells, it was suggested that increase in the viable count of HHP-treated cells in TSB and PBS could be ascribed to the recovery of colony forming ability and/or proliferation depending on the cold storage temperature.     

Photothermal waves for two temperature with a semiconducting medium under using a dual-phase-lag model and hydrostatic initial stress

The dual-phase-lag (DPL) model with two different time translations and Lord–Shulman (LS) theory with one relaxation time are applied to study the effect of hydrostatic initial stress on medium under the influence of two temperature parameter(a new model will be introduced using two temperature theory) and photothermal theory. We solved the thermal loading at the free surface in the semi-infinite semiconducting medium-coupled plasma waves with the effect of mechanical force during a photothermal process. The exact expressions of the considered variables are obtained using normal mode analysis also the two temperature coefficient ratios were obtained analytically. Numerical results for the field quantities are given in the physical domain and illustrated graphically under the effects of several parameters. Comparisons are made between the results of the two different models with and without two temperature parameter, and for two different values of the hydrostatic initial stress. A comparison is carried out between the considered variables as calculated from the generalized thermoelasticity based on the DPL model and the LS theory in the absence and presence of the thermoelastic and thermoelectric coupling parameters.     

Depth‐integrated,non‐hydrostatic model with grid nesting for tsunami generation,propagation, and run‐up

Tsunamis generated by earthquakes involve physical processes of different temporal and spatial scales that extend across the ocean to the shore. This paper presents a shock‐capturing dispersive wave model in the spherical coordinate system for basin‐wide evolution and coastal run‐up of tsunamis and discusses the implementation of a two‐way grid‐nesting scheme to describe the wave dynamics at resolution compatible to the physical processes. The depth‐integrated model describes dispersive waves through the non‐hydrostatic pressure and vertical velocity, which also account for tsunami generation from dynamic seafloor deformation. The semi‐implicit, finite difference model captures flow discontinuities associated with bores or hydraulic jumps through the momentum‐conserved advection scheme with an upwind flux approximation. The two‐way grid‐nesting scheme utilizes the Dirichlet condition of the non‐hydrostatic pressure and both the horizontal velocity and surface elevation at the inter‐grid boundary to ensure propagation of dispersive waves and discontinuities across computational grids of different resolution. The inter‐grid boundary can adapt to bathymetric features to model nearshore wave transformation processes at optimal resolution and computational efficiency. A coordinate transformation enables application of the model to small geographic regions or laboratory experiments with a Cartesian grid. A depth‐dependent Gaussian function smoothes localized bottom features in relation to the water depth while retaining the bathymetry important for modeling of tsunami transformation and run‐up. Numerical experiments of solitary wave propagation and N‐wave run‐up verify the implementation of the grid‐nesting scheme. The 2009 Samoa Tsunami provides a case study to confirm the validity and effectiveness of the modeling approach for tsunami research and impact assessment. Copyright © 2010 John Wiley & Sons, Ltd.