Frequency Selectivity Behaviour in the Auditory Midbrain： Implications of Model Study

By numerical simulations on frequency dependence of the spiking threshold, i.e. on the critical amplitude of periodic stimulus, for a neuron to fire, we find that bushy cells in the cochlear nuclear exhibit frequency selec- tivity behaviour. However, the selective frequency band of a bushy cell is far away from that of the preferred spectral range in human and mammal auditory perception. The mechanism underlying this neural activity is also discussed. Further studies show that the ion channel densities have little impact on the selective frequency band of bushy cells. These findings suggest that the neuronal behaviour of frequency selectivity in bushy cells at both the single cell and population levels may be not functionally relevant to frequency discrimination. Our results may reveal a neural hint to the reconsideration on the busily cell functional role in auditory information processing of sound frequency.     

管状流通式阴离子表面活性剂电极的研制

以石墨管为基体,十六烷基三甲基溴化铵为电活性物质,制备了带有内参比电极(Ag/AgC l)的管状流通式阴离子表面活性剂选择性电极,对其性能进行了测试。实验结果表明,其线性响应范围为1.6×10-7~5.1×10-3mol/L,斜率为52.0 mV/dec,检出限为2.0×10-8mol/L。利用该电极进行测试时,常用的无机阴离子C l-、SO42-、NO3-、PO43-等不会对其产生干扰;该电极适宜的pH值范围为2.50~10.50。对水样测定,回收率为95%~104%。电极可连续使用50 d左右。     

Single Qubit and Its Universal Logic Gate Made of a Heisenberg Spin Cluster with Five Particles

We investigate an anisotropic Heisenberg spin cluster with five particles controlled by a time-dependent magnetic field. With the algebraic dynamical method, we obtain the exact analytical solution to the time dependent Schr6dinger equation. Based on the analytical solution, it is shown that the system can be used as a universal single qubit logic gate controlled by the strength and frequency of the magnetic field, and the six special single qubit logic gates can be realized physically. We also discuss the anti-decoherence property of the qubit and its logic gates resulted from particle coupling effect and collectivity of the cluster.     

Selection Principles and Sierpinski Sets

We show that a set of real numbers is a Sierpinski set if, and only if, it satisfies a selection property similar to the familiar Menger property.     

核反应中亏损的质量哪里去了

核反应中亏损的质量哪里去了?这是“原子核”一章困扰着同学们的一个难题．课本并没有深入解释，只是简单定性地指出“原子核的质量要比组成它的核子的质量小，我们把组成原子核的核子的质量与原子核的质量之差叫做核的质量亏损”；“不仅核子结合成原子核时有质量亏损，放出能量，有些重核分裂成中等质量的核，有些轻核结合成中等质量的核，也发生质量     

氧碘化学激光气固相化学反应体系热力学分析

氧碘化学激光器（COIL）的发展已经到了提高系统安全性和工作环境适应性、降低系统复杂性阶段，而改进O2（^1△g）的产生方式和方法正是这个阶段的重要工作内容之一。近期，美国空军研究实验室运用气-固相反应方式产生O2（^1△g）。采用碱金属过氧化物或碱土金属过氧化物与卤化氢反应，生成O2（^1△g）。通常气一固相反应有着反应速度慢，接触面积小，反应产物难以脱出固体表面的缺陷，使得产出率低，而不被广泛采用。但随着表面化学研究的突飞猛进，借助表面活化分子，特殊性质的表面构造，大表面的构造，都为气一固相反应的进行提供了可行途径。如果此方法能用在氧碘激光器上，将克服传统方法的诸多不足。     

氟离子选择电极法在测试中应注意的事项

氟是人体必需的微量元素 ,成年人平均每人每天氟安全和适宜的摄入量为 3.0～ 4 .5ｍｇ[1] ,过多过少都可能引起疾病。氟元素广泛地存在于地表、水体及大气中 ,为食品检验、饮料生产、环境监测、土壤、水质及医药卫生等各个领域的常测项目。其常用的测定方法有茜素酮比色法和氟离子选择电极法。前者是一般化验室常用方法 ,使用试剂较多 ,但结果准确 ;氟离子选择电极法具有电极结构简单牢固、元件灵巧、灵敏度高、响应速度快、便于携带、操作简单 ,能克服色泽干扰 ,以及精度高等优点而被广泛地应用。目前 ,氟离子选择电极法有着逐步取代比色法…     

Effect of the Initial Mass Function of Primaries on Binary Stellar Populations

Using evolutionary population synthesis technique, we explore the behaviour of the integrated U-B,B-V, V-R and R - I colours, the integrated spectral energy- distributions (ISEDs) and Lick/IDS absorption-line indices of instantaneous burst solar-metallicity binary stellar populations, as a function of the initial mass function (IMF)of primaries. It is found that the variation of the IMF of primaries produces a small effect on the integrated colours and the Lick/IDS indices, while a significant difference in the absolute ISEDs.     

COIL中稀释气体对单态氧产率影响的实验研究

 利用自发Raman散射光谱对射流式氧发生器的单态氧产率进行了测试，研究了稀释气体对于发生器产率的影响，并分析了造成影响的原因