端粒酶研究进展

端粒酶是一种特殊的逆转录酶,是由RNA和蛋白组成的核糖核蛋白复合体,解决染色体的末端复制问题.端粒酶的激活可能与其亚单位特别是端粒酶活性催化亚单位的表达、调控有关.端粒酶在细胞的增殖、衰老及肿瘤诊断、治疗中起重要作用,有广泛的应用前景.     

Exploring the orientations of international students in Mexico: differences by region of origin

This study examined the dispositions, experiences, and expectations of international students in a developing country to understand the increasing phenomenon of reverse student flows and the role of the political economy in international student mobility. Students’ dispositions, experiences and expectations—referred here collectively as “orientations”—served as the guiding framework for this study. Data were drawn from survey responses from 279 international students at universities throughout Mexico and analyzed to explore the orientations among students from Europe, Latin America and North America. Findings showed significant differences among international students’ dispositions, experiences, and expectations by these geographical regions of origin. In a broader context, this research addressed the important role of developing countries as not only senders but also receivers of international students. This research also demonstrated the ways that the political economy shape the orientations of students studying abroad.     

Blended university teaching using virtual learning environments: conceptions and approaches

This paper reports findings from a phenomenographic investigation into blended university teaching using virtual learning environments (VLEs). Interviews with 25 Computer Science teachers in Greek universities illuminated a spectrum of teachers’ conceptions and approaches from ‘teacher-focused and content-oriented’, through ‘student-focused and content-oriented’, to ‘student-focused and process-oriented’. Using VLEs was described as a means of supporting: A—information transfer; B—application and clarification of concepts; C—exchange and development of ideas, and resource exploration and sharing; D—collaborative knowledge-creation, and development of process awareness and skills. The study suggests that pedagogical beliefs and circumstances underpinning face-to-face teaching are more influential in shaping approaches to blended VLE use than VLE system features. The authors propose that the findings could be used to inform educational enhancement initiatives and that there is a need for further discipline-focused research on blended teaching.     

Silence of the genes

The 2006 Nobel Prize in Physiology or Medicine was awarded to Andrew Fire and Craig Mello for discovering “RNA interference—genesilencing by double-stranded RNA”. The Nobel Committee at the Karolinska Institute in Sweden selected them for the award for unraveling “a fundamental mechanism for controlling the flow of genetic information” that is “already being widely used in basic science as a method to study the function of genes and may lead to novel therapies in the future”. This has been one of the fastest Nobel Prizes conferred in physiology or medicine, considering that Fire and Mello published their path-breaking article in the journal Nature in 1998, less than ten years ago. Utpal Nath is an Assistant Professor in the Department of Microbiology and Cell Biology, IISc. His laboratory is studying the genetic mechanisms of plant development. Saumitra Das is an Associate Professor in the Department of Microbiology and Cell Biology, IISc. His laboratory is interested in the translational control of cellular and viral RNA.     

How to protect the chromosomal ends? Telomerase, chromosome stability and aging

The 2009 Nobel Prize in Physiology or Medicine was jointly awarded to three scientists — Elizabeth H Blackburn, Carol W Greider and Jack W Szostak — for their work during early 1980s and 1990s which helped unravel the molecular mechanisms of protection of chromosomal ends by telomeres and the enzyme telomerase. Their discovery has had major implications in the fields of ageing and cancer research. Blackburn and Greider are the ninth and tenth women scientist, to get this award in physiology or medicine and this is the first time that two women scientists have shared the prize.     

Detection of bacterial DNA by PCR and reverse hybridization in the 16s rRNA gene

The clinical diagnosis of sepsis is difficult, particularly in neonates. To devise a rapid and reliable method for identifing bacteria in blood and cerebrospinal fluid (CSF), we developed a pair of primers according to the gene encoding 16 s rRNA, found in all bacteria. DNA fragments from different bacterial species and from clinical samples were detected with polymerase chain reaction (PCR), and with reverse hybridization using a universal bacterial probe, a gram-positive probe and a gram-negative probe. Our results showed that a 371 bp DNA fragment was amplified from 20 different bacterial species. No signal was observed when human DNA and viruses were used as templates. The sensitivity could be improved to 10⁻¹² g. All 26 culture-positive clinical samples (22 blood samples and 4 CSF samples), were positive with PCR. The gram-negative and gram-positive probe hybridized to clinical samples and to known bacterial controls, as predicted by Gram’s stain characteristics. Our results suggest that the method of PCR and reverse hybridization is rapid, sensitive and specific in detecting bacterial infections. This finding may be significant in the clinical diagnosis of sepsis in neonates. Project (396457) supported by the Zhejiang Provincal Natural Science Foundation.     

The contribution of epistemology to curriculum construction in the sciences

Summary The paper focuses upon curriculum planning in the scientific disciplines at university level, although it is claimed the argument may be of wider applicability. Drawing upon the writings of philosophers of education from several decades ago (notably Schwab and Scheffler) whose work is too often overlooked in contemporary debates about the curriculum, and using illustrative examples from the author’s own experience, it is argued that too often the focus of science curriculum planning is the “rhetoric of conclusions” or the “substantive structure” — the current state of knowledge at the forefront of the respective disciplines — to the neglect of what Schwab called the “syntactical structure” of the sciences (which roughly approximates their epistemology). This aspect of these disciplines is essential for the general student trying to become familiar with the nature of science as a broad field of knowledge, for prospective teachers, and — contra Scheffler’s view — for students who aim at careers as researchers.

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Zusammenfassung Der Beitrag der Epistemologie zur Curriuculumkonstruktion in den Naturwissenschaften Der Aufsatz fokussiert auf die Curriculumplanung für den naturwissenschaftlichen Unterricht in der universit?ren Lehrerausbildung, wenngleich behauptet wird, dass dieses Argument weitreichendere Anwendbarkeit besitzt. Der Text knüpft an erziehungswissenschaftlichen Schriften (insbesondere von Schwab und Scheffler) an, deren Ver?ffentlichung zwar einige Dekaden zurückliegt, deren Beitrag in den aktuellen Debatten aber oft übersehen wird. Darüber hinaus werden einige illustrative Beispiele aus dem Erfahrungsschatz des Autors genutzt, um zu zeigen, dass der Fokus der Curriculumplanung für die Naturwissenschaften — dem augenblicklichen Wissensstand der zu berücksichtigenden Disziplinen zufolge — zu oft in einer „Rhetorik der Schlussfolgerung“ oder „substantivischen Struktur“ besteht, was dazu führt, dass das, was Schwab die „syntaktische Struktur“ der Naturwissenschaften nennt (und ihrer Epistemologie ziemlich nahe kommt), vernachl?ssigt wird. Dieser Aspekt jener Disziplinen ist besonders wichtig für Studierende, die allgemeinbildend vertraut werden m?chten mit den Naturwissenschaften, für angehende Lehrer und — entgegen Schefflers Ansicht — für Studenten, die eine Karriere als Forscher anstreben.

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“When walking in quicksand country, carry a stout pole — it will help you get out should you need to. As soon as you start to sink, lay the pole on the surface of the quicksand. Flop onto your back on top of the pole. Work the pole to a new position: under your hips and at right angles to your spine. Take the shortest route to firmer ground, moving slowly.” Piven/Borgenicht 1999, p. 18

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This paper was presented at the conference Silence Between the Disciplines, Berlin-Brandenburg Academy of Sciences, Berlin, October 2002.     

Silents Please

Conclusions It is quite evident that the auditory aspects of the film used in the study superseded the visual ones. Since both sensory modalities can reinforce each other in many films, those films can be used to educational advantage. Behavioral science films, however—placing most importance not on the habit of looking, but on the power to observe with care—should be produced and selected with caution. Such films should present only material that is visually and auditorily congruent. Lacking this congruency, the films may teach what is said, not what is seen, a procedure that defeats the very purpose of the film. This kind of film teaching may further authoritarianism and armchair “philosophy, ” and may weaken the habit of accurate observation, essential both to scientific methodology and to successful everyday living. It is difficult to compare the results of this study directly with the results of other studies, since—as Allen has pointed out (1)—there is a dearth of experimental research involving “flat” pictures. Hartman, however, recently commenting on the interference and facilitation between pictorial and verbal channels, pointed out that it is dangerous to assume a mutual strengthening (3). Results of the experiment reported here suggest again that the viewer when presented “equivocal” material gives precedence to audition. By thus accepting and remembering only the narrator’s point of view, he may narrow his own judgment and inquisitiveness. In such cases, silents please!     

The 21st Century: The Century of the American Research University

Higher education in America has experienced periodic “inflection points” that have served to significantly alter the higher education landscape and dramatically change the focus and actions of the American research university community. We are on the leading edge of a new inflection point that could be—despite prevailing economic challenges—an opportunity for higher education to meet and address some of the great challenges facing our nation, such as economic competitiveness, health care and health care delivery, and environmental sustainability. These are challenges higher education is, in fact, uniquely suited to address.     

Lexical decision and oral reading by poor and normal readers

The primary goal of this study was to compare a paper-and-pencil version of the lexical decision task, which can be administered groupwise, with reading aloud a differently ordered list of the same words and pseudowords. Participants were first and second graders (“normal readers”) and students from schools for children with learning difficulties. On the average, the latter “poor readers” scored at the same oral reading level as the normal readers, but were older. The correlation between both tasks appeared to be high and both tasks had comparable correlations with third variables, suggesting that performance is determined by the same processes. Because the lexical decision task showed little evidence for guessing, it may be an — even better — alternative for oral reading. No differences between participant groups were found that point to different reading strategies. Error analysis, however, indicates that the poor readers probably have a specific problem in the oral reading of pseudowords.     

Specific language disability programs in Bloomington,Minnesota, public schools

V. Summary Once we clear out the undergrowth so that the Jungle of Confusion becomes a Forest of Learning, the child with a unique learning style or specific language disability can be invited into it to succeed, to learn and to “become”. There are many ways this child can go through the forest—we can find a guide to take him through, and he will be likely to see only what the guide shows him; or we can allow him to go through alone and risk the chance of losing him; or we can put him in a plane and fly him over so he can see from a distance but never get involved; or we can put him in a car and drive him around the perimeter; or we can set him on a path which will limit his exposure to learning; OR we can teach him to use a compass so he can work his way through with an independent sense of direction and security. If we honestly accept responsibility for our role in the lives of these children, wemust clean up our forest; and, we must teach children how to use a compass (basic skills). As leading explorers of knowledge, rather than merely critics of the negative or headmasters in the function of memory, or prophets of doom, we should give these children basic tools to allow them to learn and successfully develop a capacity for independent living. As Mrs. de Hirsch stated last evening, “children need living models who are intelligent—who have integrity and character”. Yes, they need models to lead them—models who believe in them, who will equip them and then let them honestly“become”. Our challenge is clear—wemust go from materials-centered teaching vagueness to child-centered teaching excellence if this Jungle of Confusion is to become a Forest of Learning. From a paper presented at the Twenty-first Annual Conference of the Orton Society, Washington, D. C., Nov. 14, 1970.     

Comparing the efficiency of Austrian universities

Summary In this paper we apply DEA to compare the efficiency of Austrian universities. It turns out that those universities that are most frequently publicly accused of working inefficiently are efficient. The Universities of Vienna and Linz and the Technical University of Graz — all three not usually the target of such attacks — show inefficiencies. We also show how to determine the changes that would have to be effected in order to make the inefficient universities efficient.     

Professionalism in early care and education

Summary Professionalism refers to the utilization of specialized knowledge that its members need to accomplish specific outcomes. It involves a shared set of skills that are used to improve the quality of caregiving practices and interactions between professional caregivers and the children and families that they work with in their respective programs. Professionalism is not an end in itself—a state of being—but an ongoing effort—a process of becoming. New knowledge of children's development needs to be incorporated into professional caregivers' existing repertoire. Their words and actions do matter greatly. As Neil Postman wrote in his book,The Disappearance of Childhood, “Children are the living messages we send to a time we will not see”.     

The role of students’ interests in self-regulated learning: The relationship between students’ interests, learning strategies and causal attributions

The purpose of this research was to examine the relationship between students’ interests, their use of certain specific learning strategies and causal attributions which they made for their academic achievement. In this manner, we attempted to explore the relationships between some important variables from three different, but connected phases of self-regulated learning: the forethought phase (interests), the performance control phase (learning strategies) and the self-reflective phase (causal attributions). Results confirmed the presumption that learning strategies could be a potential mediator in the relationship between students’ interests and their academic achievement. Also, results indicate that the causal dimension of controllability could have a partial mediating role between students’ academic achievement and their interests. Generally, our findings indicate a dynamic and cyclical nature of learning process — interest is an integral part of this process and it could be conceptualized as both a consequence and an antecedent of cognitive aspects of learning.     

Secondary school students’ perceptions of, and the factors influencing their decision-making in relation to, VET in schools

This paper addresses the issue of Vocational Education and Training in Schools — an issue that has recently attracted significant political attention particularly in light of current national skills shortage in Australia. Specifically, it investigates secondary school students’ perceptions of VET in Schools [VETiS]. It also explores the factors influencing their decision-making in relation to VETiS — that is, why one might choose, or choose not, to enrol in a VETiS course of study. In view of the findings presented, the paper argues that VET, and more particularly VETiS, is experiencing an “image problem” — one underscored by the need for curriculum design and delivery reform — and suggests that there is much work still to be done on the VET agenda.     

Young women’s dismissal of the influence of gender upon their future life trajectory as played out in ‘New Times’

This paper investigates the ways in which young women come to view gender as being an influence upon their future lives—their aspirations and expectations for the future. In doing so, it draws upon 327 surveys completed by year 12 female students, typically 17 years of age, in a range of schools across the State of Queensland, Australia. The paper details key features of the young women’s survey responses—the dominant storylines evident in the data—as a means of illustrating how they have come to dismiss gender as an influence. Further, the paper illuminates the power and pervasiveness of neoliberal discourse in ‘New Times’, the ways in which the young women surveyed embrace neoliberalism and its imperative of individualisation and do so in ways that locate gender as irrelevant in their imagining and enacting of their life biographies. Finally, the paper explores the implications of such research findings for these—and other—young women.     

Maxwell’s demon and the second law of thermodynamics

A century and a half ago, Maxwell introduced a thought experiment to illustrate the difficulties which arise in trying to apply the second law of thermodynamics at the level of molecules. He imagined an entity (since personified as ‘Mawell’s demon’) which could sort molecules into hot and cold and thereby create differences of temperature spontaneously, apparently violating the second law. This topic has fascinated physicists and has generated much discussion and many new ideas, which this article goes over. Particularly interesting is the insight given by deeper analysis of the experiment. This brings out the relation between entropy and information, and the role of irreversibility in computing as we understand it — topics still under discussion today.     

TIFRAC, India’s first computer — A retrospective

To be associated with an important and challenging activity that is being carried out for the first time in the country is a truly memorable and satisfying, even if somewhat disquieting experience. I was privileged enough to have this opportunity when I was involved in the design and implementation of India’s first computer. TIFRAC (Tata Institute of Fundamental Research Automatic Calculator) — so was it named by Jawaharlal Nehru when it was formally commissioned in 1960 — was a truly a unique computer. Some of the features of this machine are described later in this article. It is also my intention in this article to convey some of the excitement, adventure and sense of accomplishment that the successful completion of this exercise brought to the design team.     

端粒及端粒酶

端粒和端粒酶是近年来生命科学研究的热点问题之一 .端粒是染色体末端独特的蛋白质—DNA结构 ,在保护染色体的完整性和维持细胞的复制能力方面起着重要的作用 .端粒酶则是由RNA和蛋白质亚基组成的 ,能够延长端粒的一种特殊反转录酶 .端粒长度和端粒酶活性的变化与细胞衰老和癌变密切相关