忆 N. F. Mott 教授

读了《物理》杂志34卷第9期吴自勤和阎守胜两位同志写的关于N. F. Mott 教授的纪念文章,很有感触,这使我回忆起Mott 教授的一些往事.从这些往事中我深受教育,所以多年来未能忘怀.     

Fingerprints of Mott Superconductivity

We improve a previous theory of doped Mort insulators with duality between pairing and magnetism by a further duality transform. As the result we obtained a quantum Ginzburg-Landau theory describing the Cooper pair condensate and the dual of spin condensate. We address the superconductivity by doping a Mort insulator,which we call the Mort superconductivity. Some fingerprints of such novelty in cuprates are the scaling between neutron resonance energy and superfluid density, and the induced quantized spin moment by vortices or Zn impurity (together with circulating charge super-current to be checked by experiments).     

The 1/N F expansion of the γ and β functions in Q.E.D.

The Callan-Symanzik- and-functions are calculated analytically for Q.E.D. in the limit of a large number of leptons (N _F) up to terms of order 1/N _F inclusive. We give closed analytic expressions for the coefficients of these terms in their series expansion in powers ofK N _F/. We have been able to sum these series and to obtain some striking results.     

Mott对凝聚态物理学的重大贡献--纪念Mott诞辰100年

Mott N F(NevillFrancis)爵士1905年9月30日生于英国Leeds.他的父亲和母亲曾一起在剑桥大学Cavendish实验室(物理系)J.J.Thomson研究组的实验室工作过,父母亲对他成为物理学家的影响远超过中学老师.他先在Bristol的Clifton学院学习;1924-1927年在剑桥大学StJohn's学院(成立于1511年)学数学和理论物理并发表散射理论方面的论文.1928年在Fowler(Dirac的老师、著名物理学家王竹溪1935-1938年留英时的导师)的安排下从剑桥到哥本哈根Bohr的研究所等著名研究单位作访问学者、继续钻研量子力学和原子碰撞理论.     

Mott对凝聚态物理学的重大贡献——纪念Mott诞辰100年

Mott N F（Nevill Francis）爵士1905年9月30日生于英国Leeds.他的父亲和母亲曾一起在剑桥大学Cavendish 实验室（物理系）J. J. Thomson研究组的实验室工作过,父母亲对他成为物理学家的影响远超过中学老师.……     

Mott散射和电子极化术

文章回顾了Mott散射过程及其物理图像,介绍了Sherman函数的定义、计算和测量,简述了探测自旋极化电子的仪器——Mott电子极化仪的一般设计,列举了获得自由极化电子的几种方法和原理.     

Mott散射和电子极化术

文章回顾了Mott散射过程及其物理图像，介绍了Sherman函数的定义、计算和测量，简述了探测自旋极化电子的仪器——Mott电子极化仪的一般设计，列举了获得自由极化电子的几种方法和原理．     

俄国物理学家N.G.巴索夫去逝

20 0 1年 7月 1日 ,著名俄国物理学家Ｎ .Ｇ .巴索夫逝世 ,终年 78岁 .巴索夫和美国物理学家汤斯、俄国物理学普罗霍罗夫一起由于发明微波激射器、激光器和从事量子电子学方面的基础研究 ,获得过196 4年诺贝尔物理奖 .巴索夫 192 2年 12月 14日生于莫斯科南面 4 80公里的沃罗涅茨附近的乌斯曼 .194 1年在沃罗涅茨中学毕业 .卫国战争期间他在军队中服役 ,194 3年在基辅军医学校毕业 ,在军队中工作到 194 5年卫国战争胜利 .194 6年到 195 0年 ,在莫斯科机械学院学习 .从 194 8年起 ,巴索夫开始在前苏联科学院列别捷夫物理研究所的振荡实验室工…     

F. 特种高速摄影技术

本文主要介绍了激光散斑和莫尔摄影、纹影摄影、光纤技术、频闪光源和立体摄影等特种高速摄影技术。     

L.L.Beranek教授访问我国

世界著名声学家L.L.Beranek教授应魏荣爵院士邀请,在南京大学百年校庆学术报告会（2002年5月22日）上作了“音乐厅和歌剧院”的报告。白瑞纳克教授在会前和会后访问了北京和上海,分别在中国科学院声学研究所和同济大学作了“音乐厅音质的客观参量”和“音乐厅和歌剧院”等学术报告。介绍了他的丰富设计经验和卓越研究成果。并在同济大学举行他的名著《音乐厅和歌剧院》中文版首发式（王季卿、戴根华、项端析、郑敏华等译,同济大学出版社出版）。该书从音乐、声学和建筑三个方面探讨大厅音质最新进     

关于LHAASO发现PeV粒子的问答——F.Aharonian教授谈LHAASO观测结果

著名的宇宙线物理学家布如诺·罗西把宇宙线描述为“稳定持续不断的带电粒子雨,以近乎光的速度落到地球上来,每时每刻来自所有方向”。     

BEEM-π calculations for a series of pyridines and their 14N N.Q.R.

The ⁵⁷Fe Mössbauer spectrum of a powdered sample of phthalocyanine-iron(II) in an applied magnetic field of 3·0 teslas has been measured as a function of temperature in the range 4·2 K to 100 K. Measurements have also been made at 4·2 K with 6·0 teslas applied, and on a single crystal specimen at 4·2 K with 3·0 teslas applied. Independent computer fits to the three measurements taken at 4·2 K were found to be consistent with one another, and showed that detailed information concerning magnetic anisotropy can be obtained even from powdered samples of paramagnets by Mössbauer spectroscopy. Although the asymmetry parameter in the electric field gradient tensor was found to be small, there was a significant departure from tetragonal symmetry in the magnetic properties of the molecule. The magnetic hyperfine field at the ⁵⁷Fe nucleus was found to be positive in all directions, indicating that all three electronic g values are significantly greater than 2·0.     

Academician A.N. Sissakian 14.10.1944–01.05.2010

Chronicle

Academician A.N. Sissakian 14.10.1944–01.05.2010     

N型局部有源忆阻器的神经形态行为

局部有源忆阻器(locally-active memristor,LAM)凭借其高集成度、低功耗和局部有源特性等优点,在神经形态计算领域显示出巨大的潜力.本文提出了一种简单的N型LAM数学模型,通过揭示其非线性动力特性,设计了N型LAM神经元电路.采用Hopf分岔、数值分析等方法定量研究了该电路的动力学行为,成功模拟了多种神经形态行为,包括全或无行为、尖峰、簇发、周期振荡等.并利用该神经元电路结构模拟了生物触觉神经元的频率特性.仿真结果表明:当输入信号幅值低于阈值时,神经元电路输出信号的振荡频率与输入信号强度呈正相关(即兴奋状态),并在阈值处达到最大值.随后,继续增大激励强度,振荡频率则逐渐降低(即保护性抑制状态).最后,设计了N型LAM硬件仿真器,并完成了人工神经元电路的硬件实现,实验结果与仿真结果、理论分析相一致,验证了该N型LAM具备的神经形态行为.     

N型局部有源忆阻器的神经形态行为

局部有源忆阻器(locally-active memristor,LAM)凭借其高集成度、低功耗和局部有源特性等优点,在神经形态计算领域显示出巨大的潜力.本文提出了一种简单的N型LAM数学模型,通过揭示其非线性动力特性,设计了N型LAM神经元电路.采用Hopf分岔、数值分析等方法定量研究了该电路的动力学行为,成功模拟了多种神经形态行为,包括全或无行为、尖峰、簇发、周期振荡等.并利用该神经元电路结构模拟了生物触觉神经元的频率特性.仿真结果表明:当输入信号幅值低于阈值时,神经元电路输出信号的振荡频率与输入信号强度呈正相关(即兴奋状态),并在阈值处达到最大值.随后,继续增大激励强度,振荡频率则逐渐降低(即保护性抑制状态).最后,设计了N型LAM硬件仿真器,并完成了人工神经元电路的硬件实现,实验结果与仿真结果、理论分析相一致,验证了该N型LAM具备的神经形态行为.     

Novel Transitions in Doped Mott—Insulator KxCoO2

By measuring the temperature dependence of the magnetic susceptibility,two distinct transitions have been observed in potassium doped cobalt oxide KxCoO2(x=0.2-1.0).The transition around 125K corresponds to a phase transition between a weak ferromangnetic plus a strong superparamagnetic phase(below 125K) and a superparamagnetic phase(above 125K).The susceptibility above the Curie point Tc cannot be described by the Curie-Weise law,being consisten with the superparamagnetism.Mangnetizaiton-hysteresis-loops have been measured in different temperature regions to uncover the underlying physics.The second transition near 30.8k shows a strong novelty.     

Mott transition in kagomé lattice Hubbard model

We investigate the Mott transition in the kagomé lattice Hubbard model using a cluster extension of dynamical mean field theory. The calculation of the double occupancy, the density of states, and the static and dynamical spin correlation functions demonstrates that the system undergoes the first-order Mott transition at the Hubbard interaction U/W approximately 1.4 (W:bandwidth). In the metallic phase close to the Mott transition, we find the strong renormalization of three distinct bands, giving rise to the formation of heavy quasiparticles with strong frustrated interactions. It is elucidated that the quasiparticle states exhibit anomalous behavior in the temperature-dependent spin correlation functions.     

Measurement of the 15N(α, γ)19F resonances at Ec.m. = 536 keV and 542 keV

The E_c.m. = 536 keV and E_c.m. = 542 keV resonances in the ¹⁵N(α, γ)¹⁹F reaction have been studied using a thick Ti¹⁵N target, determining ωγ = (9.7 ± 2.0) × 10⁻⁵ eV and ωγ < 1 × 10⁻⁵ eV for these two resonances, respectively. For the 542 keV resonance this value is substantially smaller than had been assumed in earlier model calculations, and this reduces the rate of the analog ¹⁵O(α, γ)¹⁹Ne reaction (connecting the Hot CNO cycle and the rp-process) by a factor of ≈ 3 for temperatures in the region of T₉ = 1.