Dirac’s conception of the magnetic monopole, and its modern avatars

Conclusions Dirac’s philosophy of mathematical elegance led to his pioneering work on magnetic monopoles and inspired a large number of subsequent developments. It remains true that magnetic monopoles have never been detected, despite numerous attempts, but after all it was Dirac who once remarked, “It is more important to have beauty in one’s equations than to have them fit experiment”. One might therefore assume that he was more than satisfied with the impact of this work. This is not quite the case. Towards the end of his life, the complete lack of experimental evidence for magnetic monopoles began to weigh on him. In 1981, a year short of his 80th birthday, he was invited to Trieste for a conference to commemorate the 50th anniversary of his monopole paper. He declined the invitation due to the strain of travelling, but sent a letter of thanks to Abdus Salam, the Nobel Laureate and Director of the Centre at Trieste. In this letter, Dirac wrote: “I am inclined now to believe that monopoles do not exist. So many years have gone by without any encouragement from the experimental side.” Dirac passed away nearly two decades ago, but it remains to be determined who was right about monopoles: Dirac in 1931, or Dirac in 1981.     

电子中微子和电子的反常磁矩

由焦－宫亚夸克模型出发,过渡到Ｎａｍｂｕ模型的二体结构形式,用亚夸克动力学观点,民出了中微子和电子的反常荷,计算了电子中微子和电子的反常磁矩。     

现代审美神性的建构与科学精神的培养

审美神性早已有之,而且相当重要;就是在现代社会中,审美神性的建构也是非常重要的。审美神性的建构需要培养现代科学精神。通过科学精神的培养来建构现代审美神性具体表现为三个方面:培养批判精神,培养求实精神,培养逻辑精神。     

磁荷与磁介质球系统磁标势研究

尝试用数学模型去解决磁介质与磁荷系统的磁化、磁性质等问题，并用统一的、严谨的理论框架去解决静磁场问题。通过建立磁荷与磁介质球系统磁标势的数学模型，从理论上构建磁荷与磁介质球系统的一般框架，利用该模型可以引导分析均匀磁场中磁介质球的磁标势，磁屏蔽以及均匀磁化铁球等问题。借此还可以进一步分析磁荷与磁介质系统的磁性质、磁场、磁力等问题。解决了磁荷、磁矩与磁介质系统磁场及磁力计算方法等问题，为进一步研究磁单极与磁场、磁介质之间的性质和关系奠定理论基础。     

复杂性知识及其教育意蕴

复杂性科学视野中的复杂世界是在本体论意义上区别于简单世界的客观存在,复杂系统具有自组织、非线形、整体性、开放性、奇异性等特征。产生于大规模的复杂社会实践并指向复杂系统的复杂性知识也不同于普适、确定的简单性知识,它具有不确定性、境域性、整合性、涵疑性、深奥性等特征。复杂性知识的概念对于革新教学内容,通过复杂性知识的教学促进学生的发展,培养他们有效适应社会的能力具有重大价值。     

探情传情,拨动学生情感的琴弦

语文教学必须以美学观点把握课文的情感基调，认真分析教材。处理教材，在教学中通过各种方法，把学生带入文章的意境，引起学生的共鸣，拨动学生情感的琴弦，激发其对语文学习的兴趣与爱好，从而达到学习语文知识，陶冶美好情操，培养高尚品格，获得欣赏美，创造美的能力的目的。     

Studies on rock magnetic and paleointensity of some archaeological artifacts from Tamilnadu, India

This study investigates the magnetic mineralogy and paleointensity values of a collection of archaeological artifacts （pottery）. The actual magnetic carriers and their domain states present in the archaeological pottery were obtained using the low field susceptibility, thermomagnetic curves and acquisition of isothermal remanence. The magnetic mineralogy of all the samples was dominated by ferrimagnetic mineral （magnetite/magnetite with low titanium content）, which was suitable for paleointensity measurements. The geomagnetic paleointensity value obtained by subjecting them to modified Thellier and Thellier method, is found to be （48.81±0.15） μT.     

"文学的启蒙"与"人的文学"--从"人"的角度看中国现代审美性文学的功利观

中国现代文学的启蒙传统可分为“启蒙的文学”和“文学的启蒙”两种。“文学的启蒙”也即通常所说的审美性文学并非人们所想象的那样不讲功利,反对直接的现实功用,主张从“人”的角度实现文学内在的独特价值。其中20世纪20年代的周作人首树“人的文学”的大旗,30年代的沈从文4、0年代的徐讦分别从两个方面实践和丰富了这一主张。     

东坡惠州两相成———东坡寓惠文化及其现代利用

苏东坡寓惠时期的事业政绩、功德文望和嘉言懿行, 已和惠州的朴野山水、淳良的人心和丰富的民俗文化缠环糅合在一起, 构成了独特奇异的东坡寓惠文化现象, 所谓东坡惠州两相成。开发和利用这种文化, 对于弘扬传统文化精蕴, 以文促商, 推进惠州文化产业建设, 提升惠州知名度, 繁荣惠州现代经济具有重要意义。     

现代机械制造技术的现状和发展方向

现代机械制造技术已得到越来越广泛的应用,我国的机械制造技术水平与发达国家相比还有一定差距,21世纪机械制造技术的发展方向可用“三化”来概括,即全球化、虚拟化和绿色化。     

现代远程高等教育产业化及其模式分析

我国现代远程高等教育已经表现出比较明显的产业化与市场化倾向。现代远程高等教育之所以能够比其他教育类型率先实现产业化,除了政策法律方面的因素外,主要是由其独特的消费对象、成本利润、分配方式决定的。目前,我国现代远程高等教育已形成了主体办学型产业化模式和服务体系型产业化模式,两种模式表现不同,利弊各异。     

Mechanical and magnetic hysteresis as indicators of the origin and inception of fatigue damage in steel

N2 and N3 are known as the transition points of the three principal stages of fatigue： initial accommodation, accretion of damage and terminal fatigue. Many experiments show that the ratios of N2/Nf and N3/Nf tend to be stable even though the specific N2 and N3 values may fluctuate widely. The primary goal of this research is to study the piezomagnetic field surrounding AISI 1018 steel specimen under repeated loads and to find the ratio values of N2/Nf and N3/Nf by analyzing 11 sets of low-cycle fatigue data. An MTS-810 testing system with a peak capacity of 222 kN was used to obtain the data which consisted of stress, strain, and piezomagnetic field. A computer program was constructed to track the evolution of the piezomagnetic field and regression analysis was carried out to determine N2 and N3 values. It was observed that there exists a consistent relationship between N2 and Nf. The apparent invariance of the ratio N2/Nf implies that N2 may be identified as an index of performance in the early loading response of a specimen that forecasts its fatigue life, Nf. It has been demonstrated that measurements of the magnetic and mechanical hysteresis can yield significant insights into the various stages of the development of a fatigue critical microstructure which culminates in complete rupture of the material.     

用等效的"磁荷"讨论磁矩在磁场中受到的力、力矩及其所具有的能量

到目前为止,尽管还没有发现单个"磁荷"的存在,但是用等效的"磁荷"观点,解决一些磁性问题却颇为简便.本文将借助电矩在电场中受到的力、力矩及其在电场中所具有的能量的讨论方法,应用简要的"磁荷"观点,普通物理学的方法,得到磁矩在磁场中受到的力、力矩及其所具有的势能.     

试论现代职业教育的思想源泉和早期实践

通过历史的考察,现代职业教育的理论和实践,经历了一个从萌芽到初步形成,再到发展的演变过程。其中,大致可概括为五条线索:一是作为富国强兵途径的职业教育;二是作为改造传统教育策略的职业教育;三是作为学徒制替代品的职业教育;四是作为抉贫济困手段的职业教育;五是作为社会主义者实践的职业教育。     

回环的构建及现代运用特征

作为汉语中一种古老的、具有独特魅力的修辞方式，回环在现代语言交际中仍被广泛使用，并且呈现出范围更广、用法更活、更注重语义内涵等多种特点。其中，加大信息负载量是当今回环运用内容上最突出的特征，在齐整中追求变化是其形式上最显著的特色。     

Relationships among magnetic resonance imaging, histological findings, and IGF-I in steroid-induced osteonecrosis of the femoral head in rabbits

Objective: To study the relationships among magnetic resonance imaging (MRI), histological findings, and insulin-like growth factor-I (IGF-I) in steroid-induced osteonecrosis of the femoral head in rabbits. Methods: Thirty rabbits were randomly divided into experimental Group A (n=15) and control Group B (n=15). The 7.5 mg/kg (2 ml) ofdexamethasone (DEX)and physiological saline (2 ml) were injected into the fight gluteus medius muscle twice at one-week intervals in animals of Groups A and B, respectively. At 4, 8 and 16 weeks after obtaining an MRI, the rabbits were sacrificed and the femoral head from one side was removed for histological study of lacunae empty of osteocytes, subchondral vessels, and size of fat cells under microscopy, and the femoral head from the other side was removed for enzyme-linked immunoadsorbent assay (ELISA) for IGF-I.Results: At 4, 8 and 16 weeks after treatment, no necrotic lesions were detected in Group B, while they were detected in Group A.Light microscopy revealed that the fat cells of the marrow cavity were enlarged, subchondral vessels were evidently decreased,and empty bone lacunae were clearly increased. The IGF-I levels in Group A were significantly higher than those in Group B. At 8 weeks after the DEX injection, the MRI of all 20 femora showed an inhomogeneous, low signal intensity area in the femoral head,and at 16 weeks, the findings of all 10 femora showed a specific "line-like sign". The MRI findings of all femora in Group B were normal. Conclusion: MRI is a highly sensitive means of diagnosing early experimental osteonecrosis of the femoral head. However, the abnormal marrow tissues appeared later than 4 weeks when the expression of IGF-I increased. This reparative factor has an early and important role in response to steroid-induced osteonecrosis of the femoral head, and provides a theoretical foundation for understanding the pathology and designing new therapies.     

“家”伦理的崩毁与重建——中国现代文学经典中“家”的观念之变迁

“家”是中国传统文化的根基,但从古典到现代的转变过程中,中国的“家庭”观念却承受着巨大的变迁。首先是男性的绝对家长尊严的丧失,家庭成员由家庭本位转向社会的“群”,这使得现代家庭的建立成为可能,而“群”中“个”的建构及其“度”的问题则又成为现代家庭建立过程的一个难解之题。这种建构的困难其实是现代中国建构之艰难的一次很好的隐喻。在中国现代文学作品中《家》、《北京人》、《憩园》、《伤逝》、《寒夜》这些作品忠实地记录了这一变迁的过程,前三部记录着传统家族的衰败,而后两部则记录着现代家庭建构之艰难。     

择校收费现象的归因分析及对策思考

当前我国中小学择校现象愈演愈烈,在实际操作中常与高收费、乱收费等问题连在一起,加重了学生家庭的经济负担,影响了学校的良好声誉,严重背离了我国基础教育均衡发展的原则,社会反响强烈。只有对此进行深入的分析思考与对策研究,才能不断规范和完善择校收费的行为,使之符合我国创建和谐社会的要求。     

东江文化研究现状和外部关系问题领域

东江文化研究有两个考察视角:要素说和体系说。东江文化研究的外部关系问题领域包括东江文化与岭南文化、客家文化、惠州文化、东江流域行政区划的关系问题。     

传统文化的现代变迁与调适--以永仁县谢腊村为例

传统文化的现代变迁和转型，与其经济社会相适应，这是传统文化的必然走向。云南楚雄州永仁县谢腊彝族在长期与外来文化特别是汉文化的接触、交流、磨合乃至碰撞中，不断调适本民族传统文化，吸纳了优秀的文化成份，使彝汉文化融为一体，顺其自然地实现了传统文化的现代转型并与当代先进的科学文化嫁接。