纳米尺度下磁性隧道结的优化、制备、表征、探测及相关器件的初步研制

在非晶氧化铝（Al—O）势垒自旋阀式磁性隧道结（MTJ）和单晶氧化镁MgO（001）势垒赝式自旋阀式磁性隧道结中，室温下其隧穿磁电阻效应（TMR）分别可以达到81％和604％。     

超大磁电阻亚锰酸盐金属-绝缘体一级相变的普适性

信息技术的不断发展,促使人们不断地去研究和探索更高密度的信息存储介质和更快速的读写材料。随着金属多层膜、磁性隧道结等人工微结构材料中巨磁电阻(GMR)和钙钛矿氧化物中超大磁电阻(CMR,或称庞磁电阻)的发现,以研究、利用和控制电子自旋极化输运特性为主要内容的自旋电子学     

最佳纳米级显微图像

据<连线>杂志报道,2007年末,一个英国科学家小组首次制作了一组纳米级图像,展示了含酶入侵细菌与DNA链的实时相互作用.这些技术的始祖便是扫描隧道显微技术,这项1986的发明让其发明者荣获了诺贝尔奖.     

利用小分子干扰RNA预防和治疗SARS恒河猴实验取得进展

吸附在Au（111）表面的钻酞菁分子中心的二价钻离子的局域磁矩完全消失，不表现出近藤效应。中国科技大学合肥微尺度物质科学国家实验室（筹）侯建国和杨金龙研究组，利用扫描隧道电子显微镜探针施加电压脉冲，切除了钴酞菁分子的8个氢原子，并使钴酞菁分子以化学键的形式结合在Au（111）表面上。结果发现，在这个人造分子上钴离子的局域自旋态被恢复，而且在费米面附近出现了明显的近藤效应。     

上海盾构设计试验研究中心有限公司

盾构掘进机是隧道工程尤其是软土隧道施工的关键设备。长期以来，我国除了能够制造一些自动化程度较低的全机械盾构外，盾构机主要依赖从发达国家进口。2002年，国产盾构研制开发项目被列入“十五”国家863计划。经过一年多的努力，上海隧道工程股份有限公司研制成功了一台直径为6．34米的土压平衡盾构，实现了国产盾构设计制造零的突破。为了进一步将施工实践、机械制造和理论研究结合起来，有效提升国产盾构掘进机设计研究制造能力，进一步为开发地下空间发挥作用，在国家科技主管部门的牵头下，由上海隧道工程股份公司发起，上海科投、中铁隧道以及浙江大学、     

城市浅埋小净距超大跨岩溶隧道建造关键技术研究与应用

随着城市隧道工程的不断增加,"四新技术"的广泛应用,以及国家对城市基础设施建设质量的高标准要求,采用爆破法进行城市隧道修建,给隧道施工力学行为及工程环境影响带来了诸多问题.对此,国内外学者从复杂地质环境隧道前方不良地质体超前预报、大跨隧道施工工艺及支护结构体系受力特征等方面进行了研究.但总体而言,对复杂地质环境下的城市...     

基于Dzyaloshinsky-Moriya相互作用和人工的磁斯格明子研究

磁性斯格明子是一种实空间拓扑准粒子,它展现出丰富、新奇的物理性质,为自旋电子学的研究提供了新的方向。另一方面,由于其具有尺寸小、稳定性高、易操控等特性,在未来的存储器件中也有潜在应用价值。本文简单介绍了在国家重点研发计划量子调控与量子信息重点专项(2017YFA0303200)资助下,对基于Dzyaloshinsky-Moriya相互作用和人工的两种磁性斯格明子进行的系统研究。     

银河系英仙座旋臂W3OH星簇区距太阳系的距离为1．95千秒差距

北京谱仪国际合作组宣布，他们在分析粲粒子J／ψ衰变到1个光子和3个介子的过程中发现了一个新共振态——x1835。该共振态的质量为1835MeV，寿命约为10^-23s。研究发现其质量、谱宽及寿命与常规介子的特性不一致。目前的数据还难于明确该粒子的特性。研究人员推测它可能是一个质子．反质子束缚态（6夸克粒子），也可能是科学家长期寻找的胶子球，也有科学家认为是一个常规介子。相关研究论文发表在2005年12月31日Physical Review Letters，95，262001上。     

磁的妙用

<正>能吸引铁、钴、镍等金属的性质叫磁性。具有磁性的物体叫磁体。扬声器（喇叭）是怎么发出声音的?指南针、电磁起重机、磁悬浮列车如何工作的?核磁共振工作原理怎样?飞机隐身功能怎么实现的?绚丽极光怎样产生的?这些都跟磁有关。能吸引铁、钴、镍等金属的性质叫磁性。具有磁性的物体叫磁体。磁体一般分为硬（永）磁体(磁性保持较长或永久时间）和软磁体（较短时间内有磁性）两大类。磁体、电流均能产生磁场。磁在生活中的作用很广泛,磁性工具挂件、磁盘、     

浅谈通用型楔形管片施工控制技术

盾构隧道主体结构是由一系列预制的钢筋混凝土管片排列而成的。而管片的选型、拼装不仅会影响盾构机的姿态、设计线路，同时还会造成成型的隧道管片出现破碎、漏水等影响隧道后期使用的问题。所以做好管片的选型、拼装尤为重要。本文结合宁波市轨道交通一号线一期工程某区间使用的通用型楔形管片的工程实例，对通用型楔形管片的选型、拼装进行了分析研究，并提出了控制措施。     

Comparing the Long-Term Evolution of ``Cognitive Invariances' in Physics with a Dynamics in States of Consciousness

It is shown that the evolution of physics canin several regards be described by elements of``regression', i.e., that within a certaintradition of ideas one begins with theconstruction of most ``plausible' statements(axioms) at hand, and then ``works onselfbackwards' with respect to developmental terms.As a consequence of this strategy, the furtherwork proceeds along such a ``regressive' path,the more one arrives at concepts andrelationships which are unexpected or evencounter-intuitive in terms of our everydayexperiences. However, a comparable phenomenology is wellknown from studies on states of consciousness.In particular, the evolutionary logic of theconstructions of major ``cognitive invariances'in physics, which is in part due to everincreasing rates of data processing, ismirrored in a logic of states of consciousnesswhich deviate from a ``normal' state of dailyroutine along increasing levels of centralnervous arousal. Examples are given from the evolution ofphysics, and future perspectives are brieflyoutlined on the basis thereof.     

Informational Branching Universe

This paper suggests an epistemic interpretation of Belnap’s branching space-times theory based on Everett’s relative state formulation of the measurement operation in quantum mechanics. The informational branching models of the universe are evolving structures defined from a partial ordering relation on the set of memory states of the impersonal observer. The totally ordered set of their information contents defines a linear “time” scale to which the decoherent alternative histories of the informational universe can be referred—which is quite necessary for assigning them a probability distribution. The “historical” state of a physical system is represented in an appropriate extended Hilbert space and an algebra of multi-branch operators is developed. An age operator computes the informational depth of historical states and its standard deviation can be used to provide a universal information/energy uncertainty relation. An information operator computes the encoding complexity of historical states, the rate of change of its average value accounting for the process of correlation destruction inherent to the branching dynamics. In the informational branching models of the universe, the asymmetry of phenomena in nature appears as a mere consequence of the subject’s activity of measuring, which defines the flow of time-information.     

指南针理论在中国历史上的演变

指南针产生以后,中国学者对指南针之所以能够指南,从理论上做过探讨.这些探讨大都是从阴阳五行学说出发,结合当时人们对大地形状的认识而展开的.万历年间,传教士来华,带来了西方的指南针理论、地球学说以及相关的科技知识,在这些知识的影响下,中国学者开始从新的视角探讨指南针理论问题.在这些探讨中,阴阳五行的作用淡化了,而从力学角度做的分析却增加了,这是前所未有的.在传教士中,南怀仁的指南针理论最为系统,但他的理论仍然局限在古代科学的范围,并非吉尔伯特的磁学理论.南怀仁的理论在中国影响深远,直到19世纪中叶,仍有中国学者用南怀仁理论解释指南针问题.     

How Computational Models Predict the Behavior of Complex Systems

In this paper, we argue for the centrality of prediction in the use of computational models in science. We focus on the consequences of the irreversibility of computational models and on the conditional or ceteris paribus, nature of the kinds of their predictions. By irreversibility, we mean the fact that computational models can generally arrive at the same state via many possible sequences of previous states. Thus, while in the natural world, it is generally assumed that physical states have a unique history, representations of those states in a computational model will usually be compatible with more than one possible history in the model. We describe some of the challenges involved in prediction and retrodiction in computational models while arguing that prediction is an essential feature of non-arbitrary decision making. Furthermore, we contend that the non-predictive virtues of computational models are dependent to a significant degree on the predictive success of the models in question.     

哲学视野中的虚拟现实(VP)--兼评戈登·格雷厄姆VP技术哲学思想

文章首先简介了虚拟现实技术的概念、发展历史、特点及应用领域 ,分析了虚拟现实技术与网络虚拟性的关系。在此基础上 ,评述了戈登·格雷厄姆对虚拟现实的本体论分析。之后 ,以本体论为前提 ,评述了格雷厄姆对虚拟现实在认识论、实践论层面的理论贡献     

从美国博士学位授予情况看基础研究队伍状况

本文基于2007—2008年度美国博士学位授予情况调研报告,从美国博士学位授予概况、学科分布、性别比例、种族情况、国籍分布等特点出发,分析了博士学位授予情况对基础研究队伍的影响,探讨了在基础研究人才培养中应注意的几个问题。     

铁基超导体中的玻色模和超导电性的密切关系

铁基超导材料作为一类新的高温超导材料,其超导产生的原因一直备受关注,超导电子配对的机制一直是铁基超导研究中最具有挑战性的重大科学问题。目前有一个争论的焦点是,该类超导体是否仍然可以用BCS理论的延时电子和玻色子之间的相互作用来描述。我们通过扫描隧道谱仪,对两个不同铁基超导体系的样品进行了测量,发现除了超导特征的谱形之外,还有另一个特征峰,即玻色模,在两个样品中波色模的特征能量与中子自旋共振得到的能量数值相同,与超导临界温度之间呈现一个线性关系Ω/kBTc≈4.3±0.5。玻色模的特征峰与超导电性密切相关,并随着超导特征的减弱而减弱。上述研究结果揭示了铁基超导的非常规超导电性。     

Quantum Superpositions and the Representation of Physical Reality Beyond Measurement Outcomes and Mathematical Structures

In this paper we intend to discuss the importance of providing a physical representation of quantum superpositions which goes beyond the mere reference to mathematical structures and measurement outcomes. This proposal goes in the opposite direction to the project present in orthodox contemporary philosophy of physics which attempts to “bridge the gap” between the quantum formalism and common sense “classical reality”—precluding, right from the start, the possibility of interpreting quantum superpositions through non-classical notions. We will argue that in order to restate the problem of interpretation of quantum mechanics in truly ontological terms we require a radical revision of the problems and definitions addressed within the orthodox literature. On the one hand, we will discuss the need of providing a formal redefinition of superpositions which captures explicitly their contextual character. On the other hand, we will attempt to replace the focus on the measurement problem, which concentrates on the justification of measurement outcomes from “weird” superposed states, and introduce the superposition problem which focuses instead on the conceptual representation of superpositions themselves. In this respect, after presenting three necessary conditions for objective physical representation, we will provide arguments which show why the classical (actualist) representation of physics faces severe difficulties to solve the superposition problem. Finally, we will also argue that, if we are willing to abandon the (metaphysical) presupposition according to which ‘Actuality = Reality’, then there is plenty of room to construct a conceptual representation for quantum superpositions.     

Quantum Mechanics and Computation

In quantum computation non classical features such as superposition states and entanglement are used to solve problems in new ways, impossible on classical digital computers.We illustrate by Deutsch algorithm how a quantum computer can use superposition states to outperform any classical computer. We comment on the view of a quantum computer as a massive parallel computer and recall Amdahls law for a classical parallel computer. We argue that the view on quantum computation as a massive parallel computation disregards the presence of entanglement in a general quantum computation and the non classical way in which parallel results are combined to obtain the final output.     

Bloc Voting in the United States Senate

blocs and legislative measures are partitioned into types so that, as nearly as possible, votes by each bloc for each type of measure are either all YEAs or all NAYs. A probability model is given for the partitions into blocs and types, and for the pattern of YEAs and NAYs given the partitions. The Alternating Randomized Combination algorithm is presented for searching for high probability partition pairs. The probability of each bloc and type in the final optimal partition pair is estimated by Markov Chain Monte Carlo. The final partition identifies 18 blocs of Senators, and 14 types of legislative measures. The blocs and types are delineated in a table reporting all decisive votes in the 103rd Congress. The blocs are characterized by the types of measures in which they vote against the majority party.