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Theorems are stated and proved that provide necessary and sufficient conditions for practical stability of discrete-time systems.The first part of the paper deals with stability and instability with respect to time-varying sets, whereas the second part is devoted to the study of final and semi-final stability. The conditions obtained, which take the form of existence of discrete Lyapunov-like functions, generalize previous results. 相似文献
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Irina Tsybina Luigi E. Girolametto Elaine Weitzman Janice Greenberg 《Early Childhood Education Journal》2006,34(2):177-185
This study examined linguistic recasts provided by 16 early childhood educators to preschool children learning English as a second language (EL2). Recasts are semantic and syntactic revisions of children’s utterances. The educator–child interactions were filmed during book reading and play dough activities with small groups of four children, one of whom was EL2. The EL2 children were rated by their educators as having less well-developed expressive language skills than their unilingual peers. However, despite this finding, educators provided similar rates of recasts to both groups of children. Eight EL2 children with the lowest expressive language skills demonstrated fewer uptakes of their educator’s recasts in comparison to EL2 children with higher expressive language skills. The implications of this study include increasing the rate of recasts and reducing their complexity to provide language-learning opportunities for all preschool children, especially for those learning English as a second language. 相似文献
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Langeveld M. J. Idenburg Ph. J. Quattrocchi Luigi Völcker Otto de Bousingen R. Durand Gillett C. R. E. Trébous Madeleine Bohnsack Fritz Kirchhoff Hans Lauwerys J. A. L. 《International Review of Education/Internationale Zeitschrift für Erziehungswissenschaft/Revue internationale l'éducation》1956,2(3):345-359
International Review of Education - 相似文献
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Luigi Filippini 《Economics of Education Review》1981,1(3):367-379
A human capital approach is assumed to explain wage differentials among workers in an input-output framework, where skilled workers are produced by means of goods and labor of different kinds. The first part discusses the solution of the input-output system; wage differentials are analyzed in terms of the rate of profit. In the second part, on the basis of an education matrix compiled ad hoc, hypothetical wage differentials are calculated according to education costs and the changes of skill prices at various levels of nonwage incomes derived. 相似文献
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This paper has two main objectives. First, it presents the new relationships between the State (the Ministry of the University)
and each university in Italy, and the evaluation system established in 1996 and revised by a recent law passed in October
1999. Second, it focuses on the characteristics of the evaluation system which has to be implemented, in order to verify the
universities programmes, as well as their results in terms of efficiency, effectiveness and quality. Particular attention
is devoted to the system of indicators to be used for thee valuation and for the allocation of specific funds in terms of
incentives, and to their possible effects on the decisions of the universities' management. Finally, appropriate statistical
methods to analyse the system of indicators considered are highlighted.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
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Scilla Grassi Monica Favaro Patrizia Tomasin Luigi Dei 《Journal of Cultural Heritage》2009,10(3):347-355
The present study dealt with the characterisation of marble surfaces coated by three kinds of polymeric material usually employed in stones conservation and with the evaluation of the removal of these coatings from the surfaces by means of new nanocontainer aqueous systems constituted of micellar solutions (MS) and oil-in-water microemulsions (MC). The polymeric coatings were also subjected to accelerated artificial ageing in order to detect possible effects associated to natural photochemical ageing. The aim of the work was the assessment of the performance of such nanocontainer aqueous systems taking acetone (Ac) as a reference “traditional” solvent for the removal procedure. The characterisation was carried out by means of Scanning Electron Microscopy (SEM) and Environmental Scanning Electron Microscopy (ESEM), Fourier Transform Infra-Red (FTIR) and Nuclear Magnetic Resonance (NMR) spectroscopies and the results obtained showed that the performance of these innovative methods based on nanocontainer aqueous systems can be considered highly promising in the view of a “green approach” to the conservation of cultural heritage. 相似文献
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Maamer Slimani Nicola Luigi Bragazzi David Tod Alexandre Dellal Olivier Hue Foued Cheour 《Journal of sports sciences》2016,34(24):2338-2349
ABSTRACTSoccer players are required to have well-developed physical, technical and cognitive abilities. The present systematic review, adhering to Preferred Reporting Items for Systematic reviews and Meta-Analysis guidelines, examined the effects of cognitive training strategies on motor and positive psychological skills development in soccer performance and identified the potential moderators of the “cognitive training–soccer performance” relationship. Thirteen databases were systematically searched using keywords related to psychological or cognitive training in soccer players. The review is based on 18 studies, employing 584 soccer players aged 7–39 years. Cognitive strategies, particularly imagery, appear to improve sports performance in soccer players. Regarding imagery, the combination of two different types of cognitive imagery training (i.e., cognitive general and cognitive specific) has a positive influence on soccer performance during training, whereas motivational imagery (i.e., motivational general-arousal, motivational general-mastery and motivational specific) enhance competition performance. Younger soccer players employ cognitive general and cognitive specific imagery techniques to a greater extent than older soccer players. Combined cognitive training strategies were more beneficial than a single cognitive strategy relative to motor skills enhancement in elite (particularly midfielders) and amateur (i.e., when practising complex and specific soccer skills in precompetitive period) soccer players. In conclusion, it appears that there are differences in cognitive/psychological training interventions, and their efficacy, according to whether they are directed towards training or competition, and the age, standard and playing position of the players. 相似文献
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This paper introduces a set of services for the creation of on-line surveys, questionnaires, exams and self-assessment tests within a virtual community system used in e-learning settings. The system, called ＂Online Communities＂, is a dynamic web application used as platform for blended learning activities by the Faculty of Economics of the University of Trento. The functionalities added to the platform are contextualized into virtual communities, where activities take place. This allows us to create, submit and analyze questionnaires within and/or outside the boundaries of a community. Furthermore, the system allows to manage libraries of queries organized by the teacher/administrator of the community according to topics and levels of difficulty, in order to produce tests and generate self-assessment sessions on behalf of students. The addition of a questionnaire/ poll/self-assessment tool to a virtual community system can add a lot of interesting features, mainly using the inheritance mechanism implemented among different hierarchically-connected communities. This paper will present these functionalities and highlight one of these services, precisely the one dedicated to self-assessment. In the system, self-assessment tests have indeed a double nature： （1） They are useful to students for checking their own level of preparation; and （2） They are useful to lecturers as an indicator of the level of preparation reached by the students. In order to encourage the use of the system within the whole educational process, and not to limit the real use of the service to the period of the final exams only, the possibility has been foreseen for each participant to share his/her own test results, comparing them with the other members of the community, and even offering real ＂challenges＂, thus transforming passive and ＂solitary＂ learning into something much more stimulating and ＂social＂. 相似文献