动量相关作用对两体耗散同位旋效应的重要性

利用同位旋相关的量子分子动力学,研究了中能重离子碰撞中动量相关的状态方程对原子核阻止基于两体耗散的同位旋效应的影响.计算结果表明原子核阻止对同位旋相关和同位旋无关的核子–核子碰撞截面(两体耗散)的差值强烈地依赖于动量相关势,即在有动量相关势的情况下原子核阻止对同位旋相关和同位旋无关的核子–核子碰撞截面的差值大于没有动量相关势的情况.这就意味着动量相关作用明显地提高了原子核阻止对于核子–核子碰撞截面的灵敏性.因此,在考虑动量相关势的情况下,原子核阻止可以更准确地作为提取同位旋相关的核子–核子碰撞截面的一个探针.     

动量相关作用对同位旋相关平均场的重要性

利用同位旋相关的量子分子动力学,通过原子核阻止研究了中能重离子碰撞中动量相关作用对于同位旋相关的平均场(对称势)的重要性.计算结果表明动量相关作用同时加强了原子核阻止对于对称势和核子–核子碰撞截面同位旋效应的灵敏性.但相对而言核子–核子碰撞截面对于原子核阻止的作用远大于对称势对于它的作用,等价于动量相关作用提高了原子核阻止对于核子–核子碰撞截面同位旋效应的灵敏性,而减弱了原子核阻止对于对称势的灵敏性.这样就把原子核阻止作为提取同位旋相关的核子–核子碰撞截面的一个探针.     

CdS_xSe_（1－x）纳米微晶的辐射跃迁过程

利用变温吸收光谱和光致发光光谱研究了ＣｄＳｘＳｅ（１－ｘ）纳米微晶的辐射跃迁过程．由Ｖａｒｓｈｎｉ公式，拟合了微晶的吸收峰随温度的变化．根据变温发射光谱，研究了发光峰位置和温度的依赖关系，并分析了吸收峰和发光峰随温度变化的快慢．对发光的动力学过程．作了简单的分析．     

CdSxSe1-x纳米微晶的辐射跃迁过程

利用变温吸收光谱和光致发光光谱研究了CdS_xSe_1-x纳米微晶的辐射跃迁过程.由Varshni公式,拟合了微晶的吸收峰随温度的变化.根据变温发射光谱,研究了发光峰位置和温度的依赖关系,并分析了吸收峰和发光峰随温度变化的快慢.对发光的动力学过程.作了简单的分析.     

Temperature dependence of photoluminescence spectra in n-type modulation-doped quantum dot arrays

Temperature dependence of photoluminescence (PL) spectra of an electrostatically prepared modulation-doped quantum dot array is investigated. We report a strong temperature dependence of the enhanced PL near the Fermi energy between 0.4 and 4.2 K under a negative bias condition, where an interconnected quantum dot array is formed. This strong temperature dependence suggests that the Fermi-surface-mediated many-body interaction between a photo-created hole and the electron-gas plays an important role in the observed enhanced PL near the Fermi energy.     

Context Independence as a Statistical Property of Hidden Variable Theories

The context dependence of Bell local hiddenvariable theory is reconsidered both in its mathematicaland physical justification. The compatibility of thecontext dependence of individual measurement results with the context independence of the statisticsof measurement results is shown to warrant theconsistency of the Bell framework with respect to theGleason no-hidden-variables theorem. Finally, a sharp distinction between context dependence and (anyform of) nonlocal dependence is defended on thebackground of some recent algebraic proofs ofnonlocality.     

Ordinal Pattern Dependence in the Context of Long-Range Dependence

Ordinal pattern dependence is a multivariate dependence measure based on the co-movement of two time series. In strong connection to ordinal time series analysis, the ordinal information is taken into account to derive robust results on the dependence between the two processes. This article deals with ordinal pattern dependence for a long-range dependent time series including mixed cases of short- and long-range dependence. We investigate the limit distributions for estimators of ordinal pattern dependence. In doing so, we point out the differences that arise for the underlying time series having different dependence structures. Depending on these assumptions, central and non-central limit theorems are proven. The limit distributions for the latter ones can be included in the class of multivariate Rosenblatt processes. Finally, a simulation study is provided to illustrate our theoretical findings.     

Temperature dependence of the macroscopic elastic limit for polycrystalline Fe-Si solid solutions

The influences of alloy composition have been examined for the temperature dependence of the macroscopic elastic limit σ″ over the range 77–293?K for polycrystalline Fe-Si solid solutions. Various factors contribute to the temperature dependence of σ″, and it is found that the variation on alloying is determined by the interaction between dislocations and dissolved atoms (substitutional and interstitial), as well as by the resistance to dislocation motion due to the short-range order; furthermore, the effect on the temperature dependence of the limit on alloying iron with silicon is determined by the short-range forces between the dislocations in the silicon atoms. Interstitial impurities tend to segregate at grain boundaries, which weakens the temperature dependence of the limit.     

Conditional independence graph for nonlinear time series and its application to international financial markets

Conditional independence graphs are proposed for describing the dependence structure of multivariate nonlinear time series, which extend the graphical modeling approach based on partial correlation. The vertexes represent the components of a multivariate time series and edges denote direct dependence between corresponding series. The conditional independence relations between component series are tested efficiently and consistently using conditional mutual information statistics and a bootstrap procedure. Furthermore, a method combining information theory with surrogate data is applied to test the linearity of the conditional dependence. The efficiency of the methods is approved through simulation time series with different linear and nonlinear dependence relations. Finally, we show how the method can be applied to international financial markets to investigate the nonlinear independence structure.     

Angle-resolved elastic peak electron spectroscopy: Role of surface excitations

We analyze the possibility of determining the surface excitation parameter (SEP) from the dependence of the elastic backscattering signal intensity on the emission angle. It has been found that the shape of this dependence is reasonably well described by the theoretical model implemented in a typical Monte Carlo simulation strategy. As shown recently, the mean percentage deviation between the experimental angular dependence and the theoretical dependence is equal to 8.82% at 200 eV, 6.28% at 500 eV and 4.69% at 1000 eV. In the theoretical model used, the surface energy losses were ignored. Close inspection of the deviations between theory and experiments indicates systematic trends that can be ascribed to the surface energy losses. We found here that taking into the account the surface energy losses further improves the agreement between theory and experiment. The total mean percentage deviation, equal to 6.65%, decreases to 5.59% if the mathematical form of the Chen formula for SEP is used, or to 5.16% if the Oswald expression is used. The material dependent coefficients in the expression of SEP derived from the emission angle dependence of the elastic peak intensity differ from these coefficients resulting from other methods. We conclude that the determination of SEP from shape of the angular dependence requires the experimental data of high quality, and the reliable theoretical model describing elastic electron backscattering.     

Quantum analysis on the four-photon interference

We present a theory for quantum interference of four photons generated by spontaneous parametric down-conversion. Detailed investigation of the dependence of fourfold coincidence count rate on time delay between the incident and the reflective pump laser pulses is carried out. Gaussian type dependence is found, and good agreement between our theoretical results and experimental data reported in the literature is achieved.     

单轴应力对量子阱红外探测器吸收波长的影响

以单轴应力作用下超晶格量子阱应变能带理论为基础,采用电子反射与干涉方法,研究了单轴应力对超晶格能带的影响,推导了单轴应力与超晶格导带子能级的定量关系。以GaAs-AlGaAs-GaAs为例,具体计算了导带中子能级对应力的依赖关系,进而给出了单轴应力对n型AlGaAs-GaAs量子阱红外探测器(QWIP)吸收波长的影响。计算结果表明,随着单轴压应力的增大,量子阱红外探测器的吸收波长表现出较明显的变化。当单轴压力增大到1.3GPa,量子阱红外探测器的吸收峰值移动了将近1.1μm,并且基本与应力呈线性关系。量子阱红外探测器吸收波长连续可调范围5.57～4.46μm。     

Threshold behavior for heavy lepton production

The azimuthal dependence of heavy lepton production by polarized electron-positron beams is found to be a sensitive function of the c.m. energy. The azimuthal dependence can distinguish between production schemes and determine the threshold energy.     

Calculation of the Ratio Between the Second and First Harmonic Signals in Wavelength-Modulation Spectroscopy for Absorption Measurement

The dependence of the ratio between the second and first harmonic signals in wavelength-modulation spectroscopy is calculated for the precise absorption measurement that is applied to gas sensing. In the calculation, the amplitude modulation of the laser is considered as well as the frequency modulation. First, the dependence of signals on peak optical depth is discussed for the Lorentzian and Gaussian lines. Next, the dependence of signals on gas concentration is calculated in a weak absorption-limit. Finally, a numerical example is explained taking into consideration both peak optical depth and gas concentration.     

The effect of artifacts on dependence measurement in fMRI

The study of effective connectivity by means of neuroimaging depends on the measurement of similarity between activity patterns at different locations in the brain, without necessarily presupposing a particular model for this dependence. When these interactions are measured using functional magnetic resonance imaging (fMRI) techniques, however, imaging and physiological artifacts create patterns of dependence that may be unrelated to cortical activity. We demonstrate some of these effects through the measurement of short-range dependencies present in fMRI scans of the primary visual cortex (V1) in the anaesthetized macaque monkey. High-field (4.7 T) fMRI scans were conducted to measure responses based on the blood oxygen level-dependent contrast mechanism, during periods of no sensory stimulation and of visual stimulation with rotating polar-transformed checkerboard gratings. Dependence between the haemodynamic activity at different spatial locations (i.e., different voxels) was measured using correlation, mutual information and functional covariance. Particular attention was paid to understanding the sources of spurious dependence that may be observed during such investigations. Two main effects were detected: (a) short-range correlations introduced by the process of image reconstruction and (b) perturbations in the haemodynamic response caused by breathing. The image reconstruction artifacts were shown to create an artificially high short-range dependence in the readout direction of the scan, and the breathing artifacts caused enhanced short-range dependence in both the readout and phase-encode directions. Additional dependence in the phase-encode direction due to image-ghosting is also possible but will not be discussed in this report, as it can be alleviated by fine adjustment of preemphasis (elimination of eddy currents). A technique is described for removing breathing artifacts, and the effect of breathing on the apparent dependence between voxels is illustrated. The correlation of haemodynamic activity with the stimulus was found to be affected by breathing, although this effect can be neutralised by averaging the haemodynamic responses over many repetitions of the stimulus. Nonetheless, patterns of dependent activity between voxels may be lost in this averaging process, which makes the removal of breathing artifacts necessary if statistical dependence and the study of effective connectivity is the primary aim of an investigation.     

A XANES study of the Cu K-edge in A2CuCl4 perovskite layers under pressure. Influence of antiferrodistortive structure

Abstract

The temperature dependence of ice resistivity R has been investigated in the diamond anvil cell (DAC) of “rounded cone-plane” type. Mean pressure is about 20 GPa, temperature interval is 4,2–273 K. Measuring R it has been detected that ice changes to metallic conductivity type state between 220–260 K. At 25 K the temperature dependence of R shows the transport current dependence.     

Diffusion transport of negative ions through the interface between cryogenic liquids

A theory of electron bubble transport through the interface between cryogenic liquids is developed based on a new approach to calculating the potential of interaction of a bubble with the interface. The theory is in good agreement with experiments on the electric-field dependence of the potential barrier near the interface between liquid ⁴He, ³He, and vacuum, as well as at the interface between ³He and ⁴He saturated solutions. It is found that the interaction potential dependence on the distance between the electron bubble and the interface is isotopically invariant to three versions of such an interface. The dependence of the lifetime of negative ions in ⁴He and ³He on the temperature and electric field has been determined using the Kramers theory.     

Spin polarization dependence of the coulomb drag at large r(s)

We find that the temperature dependence of the drag resistivity between two dilute two-dimensional hole systems exhibits an unusual dependence upon spin polarization. Our main observation is that near the apparent metal-insulator transition, the temperature dependence of the drag, given by Talpha, weakens significantly with the application of a parallel magnetic field (B(||)), with alpha saturating at half its zero field value for B(||)>B(*), where B(*) is the polarization field.     

动量相关作用在原子核阻止作为探针中的重要性

最近的研究工作表明原子核阻止强烈地依赖于两核子碰撞截面而较弱的依赖同位旋相关的平均场 (对称势 ) .故原子核阻止可以作为提取介质中同位旋相关核子 -核子碰撞截面的探针 .详细的计算表明动量相关作用在提高原子核阻止对两体碰撞的敏感性和减弱对称对称势的敏感性中起了重要作用. The role of momentum dependence equation of state on the nuclear stoppings coming from the isospin dependence of nucleon-nucleon cross section (two-body dissipation ) and the isospin dependence of the mean field (one-body dissipation) are studied by using the isospin dependence quantum molecular dynamics. A detail studies indicate that the difference between the nuclear stoppings coming from the isospin dependence and the isospin independence of in-medium nucleon-nucleon...