Wrapping interactions and a new source of corrections to the spin-chain/string duality

Assuming that the world-sheet sigma-model in the AdS/CFT correspondence is an integrable quantum field theory, we deduce that there might be new corrections to the spin-chain/string Bethe ansatz paradigm. These come from virtual particles propagating around the circumference of the cylinder and render Bethe ansatz quantization conditions only approximate. We determine the nature of these corrections both at weak and at strong coupling in the near-BMN limit, and find that the first corrections behave qualitatively as wrapping interactions at weak coupling.     

Minimax Theorems Involving Two Functions and Strictly Monotone Transformations of Their Values

Two two-function minimax theorems are proved.The concavity-convexity conditions of the twofunctions involve strictly monotone transformations and mixing of the values of the two functions,and aredescribed by the inequalities as upward and weakly downward conditions.     

Quantum secure direct communication network with Einstein–Podolsky–Rosen pairs

We discuss the four requirements for a real point-to-point quantum secure direct communication (QSDC) first, and then present two efficient QSDC network schemes with an N ordered Einstein–Podolsky–Rosen pairs. Any one of the authorized users can communicate another one on the network securely and directly.     

Hydrothermal synthesis of FeS2 for lithium batteries

Nanocrystalline FeS₂ cathode material of lithium cell was synthesized from cheap materials of FeSO₄, Na₂S₂O₃, and sulfur by a hydrothermal process. The scanning electron microscopy analysis showed the obtained material was nano-sized, about 500 nm. The X-ray powder diffraction analysis showed that the synthetic FeS₂ material had two phases of the crystalline structure, pyrite and marcasite. The phase of marcasite seems to have no negative effect on the electrochemical performance of the material. The synthetic FeS₂ showed a significant improvement of electrochemical performance for Li/FeS₂ cells.     

四阶微分方程奇异边值问题的正解

本文利用锥上的不动点指数理论,在更一般的边界条件下讨论了一类四阶奇异边值问题正解的存在性并给出了应用．     

随机截断下NA样本半参数回归模型中的相合估计

本文研究固定设计下的半参数回归模型在相应变量Yi因受到某种随机干扰而被右截断且截断分布已知时,利用所获的截断观察定义了参数β和回归函数g(·)的估计,并证明了它们均具有强相合性.     

Equation of state of the hard-disk fluid on a sphere from Percus–Yevick equation

The Percus–Yevick equation is solved numerically for hard disks on a sphere. The effect of curvature of the hosting surface is calculated, and an empirical correction to the equation of state is proposed.     

CBP/Alq3有机量子阱结构的光致发光

采用多源有机分子气相沉积系统(OMBD)制备了CBP/Alq₃有机多量子阱结构,利用电化学循环伏安特性和吸收光谱、小角X射线衍射、荧光光谱研究了量子阱的能带、结构和光致发光的特性。电化学循环伏安特性和吸收光谱的测量结果表明,CBP的最低占据分子轨道(LUMO)与最高占据分子轨道(HOMO)的位置分别为-2.74,-6.00eV,Alq₃的LUMO与HOMO的位置分别为-3.10,-5.80eV,所以CBP/Alq₃有机量子阱为Ⅰ型量子阱结构。小角X衍射测量显示,在小角的位置(2θ的范围在0°～3°)观察到了对应于量子阱结构的多级布拉格衍射峰,表明多层量子阱结构是有序的层状结构,界面比较完整,界面质量比较好。荧光光谱的研究结果表明,Ⅰ型量子阱结构可以有效地把能量从垒层传递给阱层,从而增强了阱层材料的发光。阱层的厚度对发光峰的位置影响很大,随阱层厚度减小,阱层材料的发光峰出现蓝移现象。并对引起发光峰蓝移的原因进行了讨论。     

一种新的磷化铟复合沟道高电子迁移率晶体管小信号物理模型

针对磷化铟(InP)复合沟道高电子迁移率晶体管(HEMT)的特点，对常规单沟道HEMT的小信号物理模型进行了修正，提出了一种新的用于复合沟道HEMT的小信号物理模型，用商用器件模拟软件ISE(integrated systems engineering)对其进行了仿真验证，对比了实测和仿真的I-V特性及转移特性曲线，重点研究了在InGaAs/InP双层沟道中考虑量子效应后的电场和电流密度随着不同栅电压的变化趋势，研究结果表明，由于在沟道中存在量子效应，在栅下靠源端低电场区域，电流主要分布在InGaAs沟道 关键词： 高电子迁移率晶体管 复合沟道 物理模型 磷化铟     

利用排列熵检测近40年华北地区气温突变的研究

运用一种新的动力学突变检测方法——排列熵(permutation entropy，PE)算法，计算并分析了中国华北地区52个站点1960年—2000年逐日平均气温资料的排列熵演化情况，发现中国华北地区气温在20世纪70年代中期、80年代初均发生了较大突变；进一步用经验模态分解(empirical mode decomposition，EMD)方法对排列熵序列进行逐级平稳化处理，结果发现这一地区的气温突变与准10年这一年代际时间尺度的周期变率密切相关，其原因与太阳黑子活动有着密切联系. 关键词： 华北 突变 排列熵算法 经验模态分解