On the theory of discharge in crossed fields

A model of a space charge layer that may form between cathode and anode plasmas in the presence of a transverse magnetic field is considered. Collisions are assumed not to affect the motion of electrons in the gas. It is shown that two solutions differing by cathode plasma parameters may take place. Conditions when the effect of collisions may be ignored are found.     

Kinetic modelling of the H2---O2 reaction on Pd and of its influence on the hydrogen response of a hydrogen sensitive Pd metal-oxide-semiconductor device

We have established a model for the water forming reaction on Pd in the temperature range 350–475 K. Importantly, the model takes into account the possibility that hydrogen may absorb and adsorb at interface sites on supported Pd catalysts. It is shown that already at modest conditions interface adsorption may significantly affect reaction rates. The model may also be used to quantify the response of a hydrogen sensitive Pd-MOS device during hydrogen sensing in oxygen. In the case of Pd supported on SiO₂, the concentration of interface sites is so low that interface hydrogen adsorption will have only a minor influence on a catalytic reaction. The fact that a Pd-MOS device may be used as a very sensitive hydrogen detector at atmospheric oxygen conditions, despite a steric oxygen blocking of hydrogen dissociation sites, is predicted by the model.     

Wave Function of Contract-Expanding Universe

It is shown that the wave functions of a contract-reexpanding universe may be constructed in two different ways corresponding to different boundary conditions in superspace and both may offer satisfactory inflationary scenario.     

Exact solution of the ion‐laser interaction in all regimes

We show that in the trapped ion‐laser interaction all the regimes may be considered analytically. We may solve not only for different laser intensities, but also away from resonance and from the Lamb‐Dicke regime. It is found a dispersive Hamiltonian for the high intensity regime, that, being diagonal, its evolution operator may be easily calculated.     

Influence of collective effects on lifetimes of condensed excited states

The possibility that collective effects may dramatically influence-limited lifetimes of condensed excitd states is investigated in the context of a two-band model of an insulator in a strong magnetic fiels. Two different mechanisms for suppressing autoionization are discussed which may prevent the potentially catastropic destruction of the excited state. Under appropriate circumstances, he residual low-density Auger electrons may be confined in a superconducting state and paired by excitonic fluctuations in the conduction band.     

Analysis of quadratic electrooptic response of BaTiO<Subscript>3</Subscript> crystal in ferroelectric phase

Using the example of BaTiO₃ in a ferroelectric phase it is shown that a large difference in magnitudes of individual linear electrooptic coefficients may be a reason of additional indirect quadratic contributions that are independent of real quadratic coefficients. For some directions of the applied field and light, the indirect contributions may be even larger than the real quadratic ones. Independently of nonlinear distortions that can affect applicability of technical devices, a large difference between linear electrooptic coefficients may lead to serious problems in measurements of the real quadratic electrooptic effect. The analysis is based on the extended Jones matrix calculus applied to a Gaussian beam.     

带有相位拓朴数的环形相位板调控高斯光束的梯度力

用基于德拜近似条件的矢量衍射理论研究了带有相位拓朴数的环形相位板调控高斯光束的光梯度力分布,改变相位板环形区的相对半径或当相位板的相位以一定拓扑数呈现拓扑变化时,可以调节光学系统焦点区域的光梯度力分布,形成各种非常有规则的几何形状的光陷阱,如当拓朴数分别取3,4,5,6时,可形成三角形、四边形、五边形和六边形光陷阱。此种相位板可用来构建可调的光镊系统,且通过调节相位板的各区域半径和拓扑数可以得到所希望的光陷阱。     

Contrasting mechanical anisotropies of the superfluid 3He phases in aerogel

There has been much recent interest in how impurity scattering may affect the phases of the p-wave superfluid 3He. Impurities may be added to the otherwise absolutely pure superfluid by immersing it in aerogel. Some predictions suggest that impurity scattering may destroy orientational order and force all of the superfluid phases to have an isotropic superfluid density. In contrast to this, we present experimental data showing that the response of the A-like phase to superfluid flow is highly anisotropic, revealing a texture that is easily modified by flow.     

On the propagation of photons and neutrinos in curved space-time

It is shown using a classical wave theory approach that photons and neutrinos have different propagation properties in curved space-time. It is also shown that neutrinos have the anomalous property that the sign of their energy density may change as they propagate, and they may even become ghost neutrinos in some regions.     

带有相位拓朴数的环形相位板调控高斯光束的梯度力

 用基于德拜近似条件的矢量衍射理论研究了带有相位拓朴数的环形相位板调控高斯光束的光梯度力分布,改变相位板环形区的相对半径或当相位板的相位以一定拓扑数呈现拓扑变化时,可以调节光学系统焦点区域的光梯度力分布,形成各种非常有规则的几何形状的光陷阱,如当拓朴数分别取3,4,5,6时,可形成三角形、四边形、五边形和六边形光陷阱。此种相位板可用来构建可调的光镊系统,且通过调节相位板的各区域半径和拓扑数可以得到所希望的光陷阱。     

医用生物材料的低温保存研究

生物材料的低温保存一般都要经历降温过程、低温储存过程及复温过程,其中降温过程中对生物细胞的影响最大.每一种生物细胞都有自己合适的降温速率,如能满足其这种降温速率,细胞所受到的低温损伤最小,则生物细胞的复活率最高.文中介绍程序控制变速降温装置的主要结构及几种典型生物体的降温过程.最后,对器官的低温保存进行分析讨论.     

Resonant properties of a dielectric slab with equidistant strip electrodes

It is shown that a slab with a high dielectric constant and electrodes arranged in the form of narrow parallel equidistant strips may serve as a simple and effective generator of electromagnetic radiation for the very high frequency region. Its resonant properties may serve for accurate measurements of the dielectric constant in that frequency region.     

Reduction of freeze-thaw-induced hemolysis of red blood cells by an algal ice-binding protein

Antarctic sea ice diatoms produce ice-binding proteins (IBPs) that are strong inhibitors of the recrystallization of ice. Their function may be to reduce cell damage in the frozen state. We show here that an IBP from the diatom Navicula glaciei Vanheurck also has the ability to reduce freeze-thaw damage to red blood cells and that the effect may be due to its ability to inhibit recrystallization of ice.     

Cracking of Homogeneous Self-Gravitating Compact Objects Induced by Fluctuations of Local Anisotropy

We discuss the effect that small fluctuations of local anisotropy (principal stresses unequal) may have on the occurrence of cracking in spherical compact objects. Two families of homogeneous fluid distributions are considered. For both it is shown that departures from equilibrium may lead to the appearance of cracking, only if fluctuations of local anisotropy are allowed. The case of fluctuations in an initially locally isotropic (perfect fluid) configuration deserves particular attention.     

Entropy and equilibrium state of free market models

Large adiabatic polarons in anisotropic crystals in the presence of constant magnetic field have been studied within the Holstein molecular crystal model in the continuum approximation. It was shown that magnetic field directed along the symmetry axis induces transverse confinement which may stabilize large polarons. They represent localized (soliton-like) nonlinear structure uniformly propagating along the symmetry axis and rotating around it in the same time. Such objects exist in 3D lattice provided that coupling constant and magnetic field do not exceed certain critical values. In contrast with pure 1D systems existence of large polarons is possible in a quite wider region of the values of coupling constant which may attain considerably higher values than in the pure 1D media. Furthermore, polaron effective mass, depending on the intensity of the applied magnetic field, may be considerably lighter than that of the the pure 1D polarons for the same values of coupling constant. This is the most significant difference with respect to pure 1D systems in the absence of magnetic field and may have substantial impact on polaron transport properties.     

The use of circular optical grating for measuring angular rotation of mirrors

This paper explores the feasible use of circular optical grating for measuring the rotation of mirrors that are commonly found in micro-systems. Both theoretical and experimental results show that distortion of the circular grating that is projected onto the mirror surface is a simple function of the angular rotation of the mirror. The circular grating may readily be generated using a standard Michelson interferometer or an LCD projector. Through manipulating the distance between the interferometer and the mirror surface, the diameter of the optical grating may be varied. Furthermore, the additional use of a converging lens enables a significant reduction in the size of the grating: with simple laboratory facility, small circular grating of about 400 μm is achieved for use on micro-systems. With the use of more sophisticated optical elements, the angular rotation of even smaller micro-mirrors may be measured.     

四个部分相干点源的完全相消干涉特性

使用部分相干光的干涉定律,对部分相干光照明呈正方形对称四孔干涉仪的干涉场做了研究.结果表明,一定条件下,可出现完全相消干涉,并存在光强和光谱相干度的相位奇点.与二个、三个部分相干点源的干涉做了比较.对所得结果物理上可解释为：虽然四个点源是部分相干的,但从两个点源出射场之和与从另外两个点源出射场之和却可能是完全相关的. 关键词： 相关奇点光学 完全相消干涉 部分相干光 刃型位错线     

On the surface tension of fluctuating quasi-spherical vesicles

We calculate the stress tensor for a quasi-spherical vesicle and we thermally average it in order to obtain the actual, mechanical, surface tension t \tau of the vesicle. Both closed and poked vesicles are considered. We recover our results for t \tau by differentiating the free energy with respect to the proper projected area. We show that t \tau may become negative well before the transition to oblate shapes and that it may reach quite large negative values in the case of small vesicles. This implies that spherical vesicles may have an inner pressure lower than the outer one.     

Laryngeal Manifestations of Postpoliomyelitis Syndrome

Postpoliomyelitis syndrome (PPS) is a disease that may occur in survivors of acute poliomyelitis several decades after their initial infection. It can present as dysphonia, with vocal weakness and fatigue. Swallowing, respiratory, and other laryngopharyngeal symptoms may be manifestations of the disease or they may represent worsening of previously stable and compensated deficits. Three cases of laryngeal changes in PPS with videostroboscopic and laryngeal electromyography findings highlight the features of this disorder. We review possible etiologies of laryngeal PPS, diagnostic criteria, and treatment, as well as the current literature.