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1.
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2.
The liquefaction of gases was described in Part I of the series. The normal boiling point of4He is 4.22 K. By boiling a cryogenic liquid under low pressure one can attain a temperature lower than the normal boiling point. Since the vapour pressure of a liquid cryogen decreases rapidly with decreasing temperature, a limit is set to the lowest attainable temperature by pumping on a cryogenic bath. With a liquid4He bath this is 1.2 K. However using a bath of liquid3He one can attain a temperature as low as 0.3 K.  相似文献   

3.
Karabatsos compared the power of 36 person-fit statistics using receiver operating characteristics curves and found the HT statistic to be the most powerful in identifying aberrant examinees. He found three statistics, C, MCI, and U3, to be the next most powerful. These four statistics, all of which are nonparametric, were found to perform considerably better than each of 25 parametric person-fit statistics. Dimitrov and Smith replicated part of this finding in a similar study. The present article raises some issues with the comparisons performed in Karabatsos and Dimitrov and Smith and points to literature that suggests that the comparisons could have been performed in a more traditional and more fair manner. The present article then replicates the simulations of Karabatsos and demonstrates in several ways that the parametric person-fit statistics lz and ECI4z (that were also considered by Karabatsos) are as powerful as are HT and U3 in identifying aberrant examinees in more traditional and fair comparisons. Two parametric person-fit statistics are shown to lead to similar results as HT and U3 in a real data example.  相似文献   

4.
Joseph Samuel 《Resonance》2005,10(5):54-61
In the first part of this article1 we gave an elementary introduction to Chern’s ideas and their impact on modern physics. In this concluding article we describe some more advanced applications of Chern’s ideas. This second part is some-what more demanding than the first part and is addressed to students with some background in mathematics and physics. Joseph Samuel is a theoretical physicist and by natural inclination a classical mechanic. Over the years he has strayed into other fields like optics, general relativity and very recently DNA elasticity. A unifying theme in his work is differential geometry and topology in physics. He keeps moderately fit by raising and lowering indices and relaxes by playing semiclassical guitar.  相似文献   

5.
Conclusion No one believes that Gratz/Grutter are the last word on the use of race in higher education, but there are no other cases in this area immediately on the horizon. Instead we are in a period of “gathering good data,”31 “what evidence supports your conclusion,”32 “leave a paper against what criteria.”34 The outcome of the next round of litigation may well depend on how higher education has accomplished those tasks. The academic world will be best served on this question, as on others, if persons with various ideological and methodological perspectives take part. After all, the question is supposed to be about diversity. He has been a researcher on race neutrality for the Department of Education's Office of Civil Rights. The opinions expreseed here are his own and do not necessarily represent those of any other organization.  相似文献   

6.

David Hay discusses the ways that spirituality might be defined and its relationship to morality. He notes the well-intentioned documents produced by the SCAA Values Forum but argues that they have failed to get to grips with the ‘motivating reality of spiritual insight’. Perhaps spiritual awareness cannot be taught as it is part of the biological inheritance that makes us human. If this is the case, and he believes it is, then what the teacher must do is help children become aware of this and reflect on it in the light of the culture of which they are a part. He identifies a number of significant difficulties that have to be overcome before this can be done. In the remainder of the paper he considers the implications of creating such an awareness in children, and details the responsibilities of schools and teachers in this process.  相似文献   

7.
This paper explores the possibility that virtual communities of teachers with large numbers of members (referred to as massive communities of teachers) can offer support to novice teachers by means of collaborative reflection. The paper examines and conceptualises some problems found in professional massive communities and proposes that massification can dilute what some authors have called social presence or engagement. It is argued that this dilution, among other problems, very much hinders collaborative reflection among members of the community. Collaborative reflection is argued to be a crucial part of the support that novice teachers need in their first years in the profession. Therefore, a challenge is envisioned for massive communities of teachers to avoid the dilution of social presence or engagement. The authors argue that this dilution can be overcome by the use of multiple layers within a platform, referred to as fractal design.  相似文献   

8.
“It is revealed and known in front of the One who spoke and the world came into existence that a child loves1 his mother more than his father because she appeases him with words. Therefore the Holy One Blessed be He put love of father before love of mother. And it is revealed and known before He who spoke and the world came into existence that a child fears his father more than his mother because he teaches him Torah. Therefore, the Holy One Blessed He put fear of mother before fear of father.2  相似文献   

9.
In the first part of this article, we read about Alice’s guided tour through the cellular microfactory. In the second part, I introduce the methods of studying the materials and mechanisms of the molecular machines through dialogues. The three participants in this discussion are Alice, her elder brother Alex and her father Albert. The style of presentation here is adapted from Galileo’s Dialogue Concerning the Two Chief World Systems. Albert, a professor of biophysics, emphasizes the crucial differences between the mechanisms of the natural nano-machines and those of their macroscopic counterparts. He also points out some practical applications of this interdisciplinary research in biomedical science and nano-technology. Debashish Chowdhury is a professor of Physics at IIT Kanpur. He is a theoretical physicist and the areas of his research interest are statistical and biological physics. He plays with toy models using mathematical formulae and simulates nature with computers.  相似文献   

10.
To investigate the effects of salt concentration and freeze-thaw （FT） on the first hydration shell of Zn2+ ions in Zn（NO3）2 aqueous solutions, extended X-ray absorption fine structure （EXAFS） spectroscopy was used to examine Zn K-edge EXAFS spectra of Zn（NO3）2 aqueous solutions with various concentrations before and after FT treatment. The influences of salt concentration and freeze-thaw on the structural parameters of the first hydration shell of Zn2+ ions, including hydration number, Zn-O distance and thermal disorder, were analyzed. The results show that Zn2+ ions have 3.2―6.8 nearest oxygen neighbors with the Zn-O distance being 0.202―0.207 nm. In highly concen-trated solutions, Zn2+ ions are hydrated with four water molecules in a tetrahedral form. The dilution of Zn（NO3）2 aqueous solutions increases the number of water molecules in the first hydration shell of Zn2+ ions to six with their octahedral arrangement. Both the hydration number in the first hydration shell of Zn2+ ions and the degree of thermal disorder increase when the FT treatment is operated in Zn（NO3）2 aqueous solutions.  相似文献   

11.
Modified 1-ethyl-3-(3-dimethylaminopropy) carbodiimide (EDC) method was employed to synthesize the artificial antigen of enrofloxacin (ENR), and New Zealand rabbits were used to produce anti-ENR polyclonal antibody (pAb). Based on the checkerboard titration, an indirect competitive enzyme-linked immunosorbent assay (ELISA) standard curve was established. This assay was sensitive and had a linear range from 0.6 to 148.0 μg/kg (R 2=0.9567), with the half maximal inhibitory concentration (IC50) and limit of detection (LOD) values of 9.4 μg/kg and 0.2 μg/kg, respectively. Of all the competitive analogues, the produced pAb exhibited a high cross-reactivity to ciprofloxacin (CIP) (87%), the main metabolite of ENR in tissues. After optimization, the matrix effects can be ignored using a 10-fold dilution in beef and 20-fold dilution in pork. The overall recoveries and coefficients of variation (CVs) were in the ranges of 86%–109% and 6.8%–13.1%, respectively. It can be concluded that the established ELISA method is suitable for simultaneous detection of ENR and CIP in animal tissues.  相似文献   

12.
For non-negative integers k, n, let P k (n) denote the sum {fx27-1}. We show by two different means that if k ≥ 3 and odd, then n 2(n+1)2 iss a factor of the polynomial P k (n); and if k ≥ 2 and even, then n (n+1) (2n+1) is a factor of the polynomial P k (n). We also derive a relatively unknown result first obtained by Johann Faulhaber in the 17th century. Shailesh Shirali has been at Rishi Valley School, Andhra Pradesh (Krishnamurti Foundation India) since the 1980’s. He has a deep interest in teaching and writing about mathematics at the high school/post school levels, with particular emphasis on problem solving and on historical aspects of the subject. He has been involved in the Mathematics Olympiad movement at the national and international level for the past two decades. He is the author of several expository books and articles aimed at interested high school students.  相似文献   

13.
Abstract

French poststructuralist philosopher Michel Serres writes about knowledge production throughout his work. He is of particular importance to educationists because the production of knowledge shapes our discipline. But Serres is oftentimes dismissed by educationists and philosophers because of his idiosyncratic style. We argue that his style makes him unique. Serres’s style helps scholars think differently. In the first part of this paper, we will discuss matters of style and argue that Serres’s radical departure from the way in which traditional philosophy is written helps education scholars advance our field. In the second part of this paper, we argue that Serres’s work on knowledge production can be better understood in connection with Gilles Deleuze and Felix Guattari, Ludwig Wittgenstein, John Dewey, Martin Heidegger and Gaston Bachelard. In this paper, we will focus upon three of Serres’s books: Genesis, The Troubadour of Knowledge and The Parasite. Scattered throughout these works are Serres’s ideas on knowledge production.  相似文献   

14.
In the first part of this article we discussed the nonexistence of division algebra structures and vector products on ℝn. We now show how results fromtopology can be used to prove the results in the first article.While the discussion in the first part of the article required only elementary mathematics, this (second) part requires notions from basictopology, with which, we hope, many students at the M Sc level are familiar.  相似文献   

15.
In 1843 Hamilton discovered the quaternions and in the same year Graves found an algebra with 8 basis elements. So, mathematicians knew the division algebra structures (over ℝ) on ℝ, ℝ2, ℝ4 and ℝ8 in the first half of the 19th century itself. It took more than 100 years to prove that these are all the division algebras over ℝ. This follows from a theorem of Adams (which we will discuss in Part 2). In this part we also discuss ‘vector products’ on ℝ3 and ℝ7 and Hurwitz’s theorem on ‘sums of squares formulae’  相似文献   

16.
ABSTRACT

Tutorials/discussion classes1 are seen as an essential part of the teaching mix in the natural sciences, because that is where problems can be solved and course content is applied. Learning support provided by teaching assistants may free up the lecturer to do research, but are these assistants sufficiently well trained and well informed? Do tutorials offer learning spaces or merely activities to engage the willing student? In this paper I report on a study conducted in a science faculty of a research intensive university in South Africa. I collected data using interviews and questionnaires which gave insight into the many variants of tutor/teaching assistant2 support that exist in the faculty. Practices that seem to lead to better student learning were also foregrounded. It became evident that lecturers need to plan their tutorials as an integral part of the learning space and not as an add-on activity.  相似文献   

17.
In this short address, the Prefect of Prahova Department (judet) welcomes the participants in the Workshop. He expects that scientific dialogue among academicians from different parts of Europe will produce a creative synthesis and will assist that part of Europe only recently liberated from totalitarianism catch up. Higher education begins in the universities and reaches its highest level in research conducted in academies. Here purely scientific matters enter into fruitful dialogue with moral and philosophical strands of thought.  相似文献   

18.
纳米颗粒在水中的悬浮和团聚性能是决定它们在环境中迁移行为及潜在健康和环境风险影响范围的关键。表面活性剂不仅在环境中普遍存在,而且是工业制备纳米颗粒稳定悬浮液的主要分散剂。本文以单壁纳米碳管为代表,研究震荡扰动及稀释等模拟环境条件下其在阴离子表面活性剂溶液中的分散悬浮和团聚沉降性能,为评价纳米颗粒排放进入环境后的潜在风险提供依据。创新要点：现有研究认为,纳米颗粒由于能在水中稳定悬浮,其排放到环境中会产生长距离迁移并存在造成大范围污染的可能性和生态健康风险。在本文中,震荡扰动及稀释等模拟环境条件的研究表明,单壁碳纳米管在环境中长距离迁移并造成大范围污染的可能性和风险较小。研究方法：通过比较震荡扰动（模拟环境条件）和超声辅助两种分散悬浮方式及有无添加十二烷基苯磺酸钠（SDBS）阴离子表面活性剂条件下的单壁碳纳米管在水中的悬浮性能（图1）,研究单壁碳纳米管能否在环境中被分散悬浮。通过研究 Na＋,K＋,Ca2＋和 Mg2＋等环境主要阳离子存在时 SDBS 稳定悬浮的单壁碳纳米管悬浮性能及与 SDBS 浓度等的相关性（图6和8）,探明稳定悬浮的单壁碳纳米管能否在环境稀释过程中和环境阳离子存在下保持稳定悬浮。重要结论：在超声辅助下,单壁碳纳米管可以在 SDBS阴离子表面活性剂溶液中稳定分散悬浮,但不能在水中稳定分散悬浮。在无超声辅助、仅通过机械震荡的情况下,单壁碳纳米管无法在水中和 SDBS溶液中稳定分散悬浮。对于已经在 SDBS溶液中稳定悬浮的单壁碳纳米管,它们在 Na＋,K＋,Ca2＋和 Mg2＋等环境主要阳离子存在时也会脱稳形成团聚沉降,且该团聚沉降行为取决于悬浮溶液中 SDBS的浓度。当 SDBS稳定悬浮的单壁碳纳米管在环境中被稀释?  相似文献   

19.
In this review essay, Francis Schrag focuses on two recent anthologies dealing completely or in part with the role of neuroscience in learning and education: The Jossey‐Bass Reader on the Brain and Learning, edited by Jossey‐Bass Publishers, and New Philosophies of Learning, edited by Ruth Cigman and Andrew Davis. Schrag argues that philosophers of education do have a distinctive role in the conversation about neuroscience. He contends that the impact of neuroscience is likely to be substantial, though not in the way its advocates imagine. It has the potential to enhance education by way of interventions that successfully alter the fundamental neural mechanisms of learning, but neuroscience is unlikely to affect classroom teaching substantially.  相似文献   

20.
Abstract

In this paper, the writer, a senior teacher in a comprehensive school, describes his role as a critical friend to two teachers who were undertaking self‐initiated action research projects as part of a school‐based, award‐bearing curriculum development scheme offered in conjunction with the local higher education institute (HEI). He concludes that such a relationship, in providing both challenge and support for colleagues who are attempting to improve practice, is a powerful vehicle for the professional development of teachers and has a positive impact on whole‐school development.  相似文献   

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