Heisenberg and ferromagnetism

Heisenberg’s contributions to the understanding of ferromagnetism are reviewed. The special features of ferromagnetism, vis-a-vis dia and para magnetism, are introduced and the necessity of a Weiss molecular field is explained. It is shown how Heisenberg identified the quantum mechanical exchange interaction, which first appeared in the context of chemical bonding, to be the essential agency, contributing to the co-operative ordering process in ferromagnetism.     

道德规范与国书馆事业

美国图书馆协会的<职业道德规范声明>提出了以图书馆事业为中心的具体原则,其<图书馆权利法案>则明确了图书馆的责任和义务.目前,美国社会和政治环境的变化为图书馆职业带来了越来越多的忧虑和压力."9·11"后出台的<爱国者法案>明显与图书馆职业道德规范中所阐述的重要原则相冲突.因此,美国图书馆协会决心抵制<爱国者法案>对知识、信息自由开放以及行使个人隐私权的限制.     

The Penultimate Teaching Machine

This paper discusses the possibility of building an electronic transducer to take the place of the existing teaching machines. The tasks that can be performed by such a machine as well as the advantages and risks involved are discussed.