Multipole effects in non-Kramers doublet system PrMg3

We performed ultrasonic measurements on a single crystal of PrMg₃. The characteristic Curie-type softening was observed in temperature dependence of transverse mode (C₁₁-C₁₂)/2 below 8 K down to 0.8 K. This softening in PrMg₃ is caused by a non-Kramers Γ₃ doublet ground state having electric quadrupoles O_u and O_v and magnetic octupole T_xyz. The elastic constant (C₁₁-C₁₂)/2 shows a minimum at 25 K, which cannot be explained by the quadrupole susceptibility based on the crystal electric field (CEF) levels. However, considering higher order (l=4) multipole, namely electric hexadecapole, the minimum around 25 K was well reproduced. At lower temperatures, a shoulder anomaly in elastic constant being deviated from the Curie-type softening was observed around 100-800 mK in (C₁₁-C₁₂)/2. This anomaly is unaffected by magnetic fields up to 14 T.     

Estimates of a certain sum involving coefficients of cusp forms in weight and level aspects

We consider the sum of coefficients which are in the Dirichlet series expansion of symmetric square L-functions. In this paper, we obtain two estimates of this sum in weight and level aspects. These imply two estimates of the sum of the n ²th Fourier coefficients of cusp forms.     

显示反射全息图单光束相干复制技术

描述用单光束激光复活制银盐白光显示反射全息图的技术，本技术的关键：１）母全息图的颜色必须恢复到满足其布拉格条件；２）复制所用的光波与记录母全息图时的参考的相同；（３）复制所用的激光采用平行偏振，以减少界面反射；９４）采用白糖溶液作为折射率匹配液，取得极佳效果。     

Effect of Intra-Dot Coulomb Interaction on Andreev Reflection in Normal-Metal/Quantum-Dot/Superconductor System

We investigate the effect of intra-dot Coulomb interaction on the Andreev reflection in a normalmetal/quantum-dot/superconductor (N-QD-S) system with multiple levels in the quantum dot, in the regime where the intra-dot interacting constant is comparable to the energy gap of superconducting lead. By using nonequilibrium Green function method, the averaged occupation of electrons in the quantum dot and the Andreev reflection (AR) current are studied. Comparing to the case of non-interacting quantum dot, the system shows significant changes for the a two-step-like behavior; and the I-Vg shows two groups of peaks, separated by U and with equal heights, where Vg is the gate voltage and U denotes the intra-dot Coulomb interaction constant. (ii) For finite bias voltage, dips, superposed V ≥ U/2, extra AR current peaks occur between the two groups of the peaks. Besides, the properties of the heights of the AR current peaks are more complicated.``     

Non-Deterministic Closure Theory and Universal Arrows

Traditional closure theory discusses the closure operations on orders with graph-theoretic methods, or the reflectors on skeletal categories with category-theoretic methods. Both approaches are confined, like most of classical mathematics, to total and deterministic operations. So traditional closure theory makes it possible to define the semantics of the while-do commands only for terminating and deterministic programming. This paper outlines a closure theory for relations which transcend totality and determinism. For the sake of conciseness, the language used is that of graph theory but the methods are category-theoretic and some hints are offered for a possible translation into the language of category theory. Our basic idea is that closure relations consist of universal arrows in the sense of category theory. The new closure theory is appropriate for defining a semantics of the while-do commands both for terminating, deterministic programming and for non-terminating, non-deterministic programming.     

Wave reflection in slightly compressible, finitely deformed elastic media

Summary  In this paper, the reflection of a plane wave at an incrementally traction-free boundary of a half-space composed of nearly incompressible elastic material is considered. It is shown that two distinct cases exist, these being dependent on the underlying primary deformation. In the first case, the appropriate slowness sections are each approximately elliptical, and the corresponding reflection phenomena closely mirrors that associated with the corresponding linear isotropic theory. Specifically, an angular range of direction of incident wave exists, for which both a quasi-longitudinal and quasi-shear wave are reflected, the former being replaced by a surface wave outside this angular range. In the second case, the outer slowness section is re-enrant and, in addition to the scenarios previously mentioned, it is possible for two quasi-shear waves to be reflected. Numerical illustrations of reflection coefficients are presented in respect of a modified Varga material and the case of increasing bulk modulus is investigated. Received 17 January 2000; accepted for publication 22 February 2000     

强激光对铜反射镜的热破坏效应

本文给出了一个激光对光学材料表面热破坏效应的简化物理模型及数值研究结果。所得到的铜反射镜热破坏阈值与激光脉宽的关系与实验和理论符合很好。提出了反射镜后表面外冷却临界厚度的概念,并得到一个关于多脉冲积累效应的幂定标关系。     

Quantum confinement without walls

We explore and demonstrate quantum confinement without walls in metal-clad InAs quantum wells. We observed intersubband absorption from confined states in InAs clad with Al, Sb, Nb, W, Pt, Ag, Au, Ti or In. We found that using this novel method, we can explore the physics and chemistry at the metal–semiconductor interface; reflection, autoionization, well-width fluctuation and interface reaction.     

Coalescence process of monodispersed Co cluster assemblies

Cluster-cluster coalescence process of monodispersed Co clusters with mean diameter d = 8.5 and 13 nm deposited a plasma-gas-condensation-type cluster beam deposition system was investigated by in situ electrical conductivity measurements and ex situ scanning electron microscopy (SEM) and transmission electron microscopy (TEM), and analyzed by percolation concept. The electrical conductivity measurement and TEM observation indicated that, below temperature T≈ 100^°C, the Co clusters in the assemblies maintain their original structure as deposited at room temperature, while that the inter-cluster coalescence takes place at T > 100^°C, although the size distribution and the interface morphology of the clusters showed no marked change at substrate temperatures T _s≤200^°C. Received 29 November 2000     

Short wavelength light reflecting films from side‐chain liquid crystal homopolymers with chiral spacers

A series of acrylate monomers with alkoxy tails of varying lengths are synthesised and polymerised. The butoxy analogue had a stable enantiotropic cholesteric liquid crystalline phase which formed a grandjean texture when prepared as a thin film between glass slides. The polymer was mixed with a low molar mass nematic liquid crystal in various proportions and the pitch of the chiral nematic phases were determined using a cano‐wedge cell technique. The polymer prepared from (S)‐2‐(4‐butoxyphenyl‐4′‐benzoyloxy)‐1‐methyl ethyl acrylate had a pitch length of 113 nm which indicates that the polymer film could be employed in optical devices requiring selective reflection of light with short wavelengths in the region of 170 nm. Copyright © 2001 John Wiley & Sons, Ltd.