Baryon number transfer in hadron + nucleus and nucleus + nucleus collisions: a link between elementary and complex interactions

The baryon number transfer is studied in elementary and complex hadronic interactions at the CERN experiment NA49 at the SPS, at 158 AGeV beam energy (√s=17.2 GeV) A two-component picture is proposed, which builds up the net proton distribution from a target and a projectile component. Using pion beam, the projectile component is experimentally determined for p + p and p + A interactions. A similar stopping behaviour of the projectile component is found for p + A and A + A interactions. Based on these observations, the baryon transfer is assumed to provide a common scale of inelasticity in p + p, p + A and A + A interactions. A model-independent way is proposed to predict the pion multiplicity in A + A.     

Distribution corresponding to classical thermodynamics

A distribution corresponding to classical thermodynamics is constructed. The concept of degrees of freedom is generalized and a concept of temperature-dependent number of collective degrees of freedom is introduced. A relationship between the theory of numbers and mesoscopic physics is established. A geometric interpretation of spinodal as a curve of maximum entropy and as a catastrophe in a quasi-static Caratheodory process is given. A concept of local ideal gas is introduced. The phase transition of fluids to a dispersed system is determined. The distribution obtained is numerically compared with the distribution for a van der Waals gas in the Hougen-Watson diagram.     

Separable states are more disordered globally than locally

A remarkable feature of quantum entanglement is that an entangled state of two parties, Alice ( A) and Bob ( B), may be more disordered locally than globally. That is, S(A)>S(A,B), where S(*) is the von Neumann entropy. It is known that satisfaction of this inequality implies that a state is nonseparable. In this paper we prove the stronger result that for separable states the vector of eigenvalues of the density matrix of system AB is majorized by the vector of eigenvalues of the density matrix of system A alone. This gives a strong sense in which a separable state is more disordered globally than locally and a new necessary condition for separability of bipartite states in arbitrary dimensions.     

A small volume thermodynamic system for B/A measurement.

A thermodynamic method capable of determining the B/A value of 4-ml sample volumes is described. The method involves a procedure in which the static pressure of the sample is altered in a short period of time, to approximate an adiabatic process, during which the ultrasonic velocity is measured. The velocity change so determined is used to calculate the B/A value. The B/A measurement error is less than 0.7%.     

高能激光束自动对准和稳定系统的结构设计

介绍了一种用于两个光学平台之间光轴自动对准和稳定光束的设计方案。以可绕ｘ,ｙ,ｚ三个方向转动的导光管为单元,组成导光臂连接两个光学平台,消除两个平台之间相对运动产生的光轴对接偏差。用压电陶瓷驱动的倾斜镜作光束稳定元件,消除光束自身的漂移和平台间高频振动产生的光轴偏差。     

Kosterlitz-Thouless-like transition in granular superconducting films

A Kosterlitz-Thouless-like transition in granular superconducting films is considered. A magnetic field fluctuations influence on thermodynamic properties is analyzed. A renormalization of an interaction constant because of “spin-wave” fluctuations is calculated. A role of a weak disorder is considered. A relationship between the transition temperature and the film sheet resistance is found to be in good agreement with experimental data. If the transition temperature is not too low the results are applicable to uniform superconducting films.     

钙离子调控微丝切割蛋白中A6亚基解折叠的单分子力谱研究

在生命活动中,金属离子扮演了非常重要的角色.微丝切割蛋白(adseverin)需要钙离子的活化才能行使其切割肌动蛋白微丝的功能.本文通过基于原子力显微镜的单分子力谱研究了微丝切割蛋白C端末的A6亚基在结合钙离子前后的力学解折叠机理.实验结果显示:在未结合钙离子时,A6的解折叠表现为两态过程;在结合钙离子后A6力学稳定性显著提高;同时,钙离子的结合使得A6解折叠过程中出现稳定的中间态.通过对中间态的链长的分析,我们推测了中间态对应着A6的N端部分解折叠.而这一部分的解折叠可以使得掩藏在该结构后的A5亚基中肌动蛋白微丝结合位点暴露,从而促使微丝切割蛋白执行功能.我们的实验结果为理解微丝切割蛋白的工作原理提供了新的实验证据.     

液舱横荡非结构网格高阶格式数值模拟

提出一种液舱横荡数值模拟的方法,将气液两相交界面视为物理间断,通过高阶精度离散格式捕捉间断.根据NVD(Normalized Variable Diagram)实现非结构化网格上高精度离散格式,建立固定网格上自由表面运动模拟方法.在开发的非结构网格有限体积法求解器GTEA(General Transport Equation Analyzer)基础上,实现上述方法.首先对经典的溃坝过程进行模拟,并与文献结果对比验证方法和程序的可信度.对二维矩形液舱在不同激振频率时的横荡进行数值计算,并与实验以及商业软件CFX计算结果进行比较.结果表明方法和软件可以模拟自由面的翻卷、破碎运动现象,对距自由面较深点处流体载荷的计算结果与实验值符合较好,与商业软件CFX相比,在相同计算网格下,算法可以更好的计算次峰值,验证方法正确可行.     

Low Noise mm-Wave Amplifier Design Methodology

A design methodology for mm-wave LNAs is presented. The optimum bias point selection is outlined. The stabilisation strategy is described, and the impact of packaging requirements on the amplifier design is discussed. A bond wire compensation technique is detailed. The tradeoff between input match and noise figure is presented, and a design with a suitable tradeoff is¹ developed. A very simple inter-stage match requirement is a novel outcome of this design approach. An effective means of achieving a broadband response is also outlined. A four stage 30 – 50 GHz LNA design was fabricated and characterised in a customised package. A maximum MMIC gain of 28 dB at 32 GHz was achieved, and the gain exceeded 20 dB over the frequency range 26 – 44 GHz. A noise figure of 4.5 dB and a P1dB of +11 dBm were also obtained. It is the authors' opinion that the methodology presented in this paper will be of significant interest to other mm-wave LNA designers.     

双光栅实现半导体激光阵列波长组束

在波长光束组合基础上,用一个光栅和一个准直透镜代替传输透镜,可以有效地减小单个发光单元光束质量的退化,明显地克服相邻发光单元的反馈串扰,实现了较窄线宽的光谱组束输出。采用标准的半导体激光阵列,连续输出激光功率44.8 W,电光转换效率最高38.9%,光谱线宽为4.1nm。光束慢轴方向光束质量因子为11.7,快轴方向光束质量因子为1.37,快慢轴两个方向都接近单个发光单元光束质量。     

Piston-type radiator in a soft screen in the pekeris waveguide

A model problem is considered for a radiator in the form of a circular disk with a given pressure jump at its surface. The radiator is inserted in a soft screen coinciding with the upper boundary of the Pekeris waveguide. A series expansion of the sound field in normal modes is obtained. A numerical analysis of the radiation impedance and its components that are responsible for the radiation into the waveguide and into the halfspace is carried out.     

Strong persistence of an attractor and generalized partial synchronization in a coupled chaotic system

It is widely believed that when two discrete time chaotic systems are coupled together then there is a contraction in the phase space (where the essential dynamics takes place) when compared with the phase space in the uncoupled case. Contrary to such a popular belief, we produce a counter example--we consider two discrete time chaotic systems both with an identical attractor A, and show that the two systems could be nonlinearly coupled in a way such that the coupled system's attractor persists strongly, i.e., it is A?×?A despite the coupling strength is varied from zero to a nonzero value. To show this, we prove robust topological mixing on A?×?A. Also, it is of interest that the studied coupled system can exhibit a type of synchronization called generalized partial synchronization which is also robust.     

Improved line narrowing and wavelength stabilization technique of distributed feedback dye lasers

A new method is described, for the wavelength stabilization and line narrowing of DFB dye lasers, using a dispersive pumping arrangement, where the wavelength shift of pumping light is compensated by a change in the incident beam angle. A predicted relation between pumping wavelength shift and DFB laser wavelength shift is verified experimentally. A twentyfold line narrowing in comparison with pumping linewidth, is realised in a preliminary experiment.     

一种新型分凝分离式混合工质内复叠节流制冷机的实验研究

混合工质节流制冷机正在许多方面获得越来越广泛的应用。文中提出了一种新型分凝分离式内复叠节流制冷循环 ,设计了一种具有内部传热和传质的分凝分离器并用此来代替传统的气液分离器 ;建立了相应的单级油润滑制冷压缩机驱动的实验系统 ,并分别进行了 1 2 0 K和 1 80 K两个温区的实验研究。在 1 30 K时获得了 60 W的制冷量 ;1 35K时获得了 74W的制冷量 ;1 55K时获得了 2 65W的制冷量。     

Quantum fluctuations of spatial dissipative solitons in a nonlinear interferometer

A quantum Langevin equation is derived that makes it possible to study the radiation field in a large-aperture nonlinear interferometer excited by external classical radiation. This equation is linearized in the vicinity of the solution for a stationary soliton. A mathematical formalism for obtaining a spectral representation of the solution to the linearized problem is constructed. It is shown that, in general, the excitation spectrum of a soliton consists of three branches, two of which belong to a continuous spectrum, while the third branch is discrete. The spectral representation obtained makes it possible to rigorously define the operator of soliton coordinate fluctuations, since, as is shown in the study, the traditional definition of this operator leads to a divergence in the vicinity of the solution. A new type of dissipative soliton is found, which is a natural generalization of a stationary soliton and takes into account its motion. A relation is found between this soliton and the contribution to the solution for field fluctuations from the discrete spectrum expansion. The mean squares of fluctuations of the soliton coordinate and momentum are calculated. A range of parameters is determined where the momentum of the soliton can always be measured with a spread smaller than the standard quantum limit. This possibility is related to the occurrence of states squeezed with respect to the soliton momentum. A scheme is proposed for the experimental observation of these states.     

Teleportation of N-qubit W State without Bell-State Measurement via SelectiveResonant Interaction in Cavity QED

We present a scheme in which the N-atom W state is teleported byemploying the selective interaction of a cavity field with a driventhree-level atom in the λ configuration and detecting a single atom in one of the ground states. The long-lived W state is teleported from atom A to atom B when the atoms B and A are sent through a cavity successively and atom A is then detected. The advantage is that the present one does not involve the Bell-state measurement and is robust against the atomic spontaneous emission.     

The ground state of a strongly correlated fermion system in a magnetic field

A new variational method is used to investigate the ground state of the Hubbard model with a half-filled band for a one-dimensional chain, a planar square lattice, and a simple cubic lattice. A metamagnetic transition is found to occur in a one-dimensional chain and a simple square lattice. A simple cubic lattice does not undergo the metamagnetic transition.     

Estimation of number of modes in periodic graphs

The problem of acoustic wave propagation in a one-periodic system of thin pipes is studied. A dispersion equation linking the time frequency ω with the propagation constant (quasimomentum) γ is derived. A particular question is studied, namely how many different values of γ can obey the dispersion equation for a fixed ω. A simple estimation of this amount is obtained in terms of the properties of the graph representing a single period of the system.     

Creating planar electrode systems for biosensors

A planar topology for a nanoelectronic transducer based on glucose oxidase is designed for use in an enzymatic biosensor. Electromigration is used to create 5-nm gaps in Au nanowires. A method for the chemical modification of a silica surface with epoxysilane is developed and glucose oxidase is immobilized on the surface of a support by means of linking molecules. A technique for biochemical signal registration is developed. The eelectric response of the biosensor with glucose in a test solution and the dependence of this response on the glucose concentration are investigated.