Laser separation of isotopes     

Willem de Ruiter 《Endeavour》1984,8(3):128-134

Laser separation of isotopes was first shown to be scientifically practicable at the start of the 1970s, when the isotopes of nitrogen, chlorine, hydrogen, and many other elements were successfully separated. Its most important applications are for uranium and plutonium enrichment. Enriched uranium is used as fuel for nuclear power stations, while enriched plutonium can be used to design more effective nuclear weapons. Ninety-eight per cent of all enriched uranium is now produced in gaseous diffusion installations, the remaining 2 per cent being produced by gaseous centrifugation. Research into laser separation is being conducted in numerous countries and will lead to the production of enriched plutonium on an industrial scale by the end of this decade.  相似文献   

Working whilst studying in higher education: The impact of the economic crisis on academic and labour market success          下载免费PDF全文

Albert Sanchez‐Gelabert  Mijail Figueroa  Marina Elias 《European Journal of Education》2017,52(2):232-245

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E-learning and Evaluation in Modern Educational System     

Tamara Tomasegovic Paula Yadranka Zitinski Elias Marina Baracic Nikola Mrvac 《美中教育评论》2011,(2):198-203

Implementation of information and communication technologies as well as emersion of new user interfaces and web 2.0 technologies changes the way of education system, the way of living and business transactions in general. The way we communicate, operate, produce and live is also changing. In accordance with it, the systems of education change from traditional to modern. The following changes occur： from content delivery to knowledge production, from transfer of knowledge from teachers to students towards encouragement of development and construction of knowledge, from courses and programs changing to the adaptation of the study environment, from the faculty professionalism to the quality of teaching and student learning and the early involvement of students in research work and projects. These occurring changes also affect the students＇ and professors＇ mobility. Here, the word ＂mobility＂ represents not only the student exchange programs and the easier transitions from one＇s home university to a foreign one, but also the way professors conduct their classes. With the development of certain software, students＇ class attendance no longer represents an important factor, as they can now learn from distance using the mentioned software, taking the learning process one step further. In order for above-mentioned changes to occur, the use of e-learning and the development of new tools are almost mandatory. With this in mind, the goal of this paper is to analyze quantitatively the changes that are occurring almost every day that affect the students＇ learning and the professors＇ teaching methods.  相似文献   

On the interplay between normalisation,bias, and performance of paper impact metrics     

Marcel Dunaiski  Jaco Geldenhuys  Willem Visser 《Journal of Informetrics》2019,13(1):270-290

We evaluate article-level metrics along two dimensions. Firstly, we analyse metrics’ ranking bias in terms of fields and time. Secondly, we evaluate their performance based on test data that consists of (1) papers that have won high-impact awards and (2) papers that have won prizes for outstanding quality. We consider different citation impact indicators and indirect ranking algorithms in combination with various normalisation approaches (mean-based, percentile-based, co-citation-based, and post hoc rescaling). We execute all experiments on two publication databases which use different field categorisation schemes (author-chosen concept categories and categories based on papers’ semantic information).In terms of bias, we find that citation counts are always less time biased but always more field biased compared to PageRank. Furthermore, rescaling paper scores by a constant number of similarly aged papers reduces time bias more effectively compared to normalising by calendar years. We also find that percentile citation scores are less field and time biased than mean-normalised citation counts.In terms of performance, we find that time-normalised metrics identify high-impact papers better shortly after their publication compared to their non-normalised variants. However, after 7 to 10 years, the non-normalised metrics perform better. A similar trend exists for the set of high-quality papers where these performance cross-over points occur after 5 to 10 years.Lastly, we also find that personalising PageRank with papers’ citation counts reduces time bias but increases field bias. Similarly, using papers’ associated journal impact factors to personalise PageRank increases its field bias. In terms of performance, PageRank should always be personalised with papers’ citation counts and time-rescaled for citation windows smaller than 7 to 10 years.  相似文献   

Personalised news and scientific literature aggregation     

Nikolaos Nanas  Manolis Vavalis  Elias Houstis 《Information processing & management》2010

Content-based filtering can be deployed for personalised information dissemination on the web, but this is a possibility that has been largely ignored. Nowadays, there are no successful content-based filtering applications available online. Nootropia is an immune-inspired user profiling model for content-based filtering. It has the advantageous property to be able to represent a user’s multiple interests and adapt to a variety of changes in them. In this paper we describe our early efforts to develop real world personalisation services based on Nootropia. We present, the architecture, implementation, usage and evaluation of the personalised news and paper aggregator, which aggregates news and papers that are relevant to an individual’s interests. Our user study shows that Nootropia can effectively learn a user’s interests and identify relevant information. It also indicates that information filtering is a complicated task with many factors affecting its successful application in a real situation.  相似文献   

Cross‐Validated Prediction of Academic Performance of First‐Year University Students: Identifying Risk Factors in a Nonselective Environment     

Eline Meijer  Marc P. H. D. Cleiren  Elise Dusseldorp  Vincent J. C. Buurman  Roel M. Hogervorst  Willem J. Heiser 《Educational Measurement》2019,38(1):36-47

Early prediction of academic performance is important for student support. The authors explored, in a multivariate approach, whether pre‐entry data (e.g., high school study results, preparative activities, expectations, capabilities, motivation, and attitude) could predict university students’ first‐year academic performance. Preregistered applicants for a bachelor's program filled out an intake questionnaire before study entry. Outcome data (first‐year grade point average, course credits, and attrition) were obtained 1 year later. Prediction accuracy was assessed by cross‐validation. Students who performed better in preparatory education, followed a conventional educational path before entering, and expected to spend more time on a program‐related organization performed better during their first year at university. Concrete preuniversity behaviors were more predictive than psychological attributions such as self‐efficacy. Students with a “love of learning” performed better than leisure‐oriented students. The intake questionnaire may be used for identifying up front who may need additional support, but is not suitable for student selection.  相似文献   

Echoes of Early Life: Recent Insights From Mathematical Modeling          下载免费PDF全文

Willem E. Frankenhuis  Daniel Nettle  John M. McNamara 《Child development》2018,89(5):1504-1518

In the last decades, developmental origins of health and disease (DOHaD) has emerged as a central framework for studying early‐life effects, that is, the impact of fetal and early postnatal experience on adult functioning. Apace with empirical progress, theoreticians have built mathematical models that provide novel insights for DOHaD. This article focuses on three of these insights, which show the power of environmental noise (i.e., imperfect indicators of current and future conditions) in shaping development. Such noise can produce: (a) detrimental outcomes even in ontogenetically stable environments, (b) individual differences in sensitive periods, and (c) early‐life effects tailored to predicted future somatic states. We argue that these insights extend DOHaD and offer new research directions.  相似文献   

巨大的挑战     

Willem Winkelman 《Reading and Writing(高中版)》2009,(Z1)

"Keep staring:I might do a trick!"That's the message on a T-shirt of mine. People stare at me all the time, so I thought this shirt would be funny.See, I'm a dwarf(矮子).  相似文献   

Do charismatic presidents influence college applications and alumni donations? Organizational identity and performance in US higher education     

Michael N. Bastedo  Elias Samuels  Molly Kleinman 《Higher Education》2014,68(3):397-415

The effect of charismatic leadership on organizational performance is contested. Yet despite the lack of consistent evidence of the value of charismatic leadership to organizations, presidential searches have increasingly favored charismatic candidates. This study shows how organizational identity mediates the relationship between charismatic leadership and organizational performance. Among religious colleges, but not among private colleges considered overall, there is a positive relationship between presidents’ charismatic leadership and the number of applications for enrollment and the amount of financial donations colleges receive. This suggests that among organizations with atypical identities, charismatic leadership can be interpreted as a meaningful signal of organizational performance.  相似文献   

Selection to the Master’s Phase at the Binary Divide,a Dutch Case Study     

van Os  Willem 《Tertiary Education and Management》2007,13(2):127-140

Tertiary Education and Management - This article presents a case study of selection for graduate study at the Vrije Universiteit (VU) in the Netherlands. The VU developed and implemented an...  相似文献