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The presence of Matthew effects was tested in students of varying reading, spelling, and vocabulary skills. A cross-sequential design was implemented, following 587 Grade 2 through 4 students across five measurement points (waves) over 2 years. Students were administered standardized assessments of reading, spelling, and vocabulary. Results indicated that the hypothesized fan-spread pattern for Matthew effects was not evident. Low and high ability groups were formed based on 25th and 75th percentile cutoffs on initial measures of spelling, reading accuracy and fluency, vocabulary, and reading comprehension. Multilevel modeling suggested that low and high ability groups had significantly different starting points (intercepts) and their pattern of growth on passage comprehension did not indicate that the gap would increase over time. Instead, some analyses, especially of the youngest cohorts, showed significant convergence. However, there was no evidence of eventually closing the gap. Thus, although the poor students may not be getting poorer, they do not get sufficiently richer either. 相似文献
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The problem of results merging in distributed information retrieval environments has gained significant attention the last years. Two generic approaches have been introduced in research. The first approach aims at estimating the relevance of the documents returned from the remote collections through ad hoc methodologies (such as weighted score merging, regression etc.) while the other is based on downloading all the documents locally, completely or partially, in order to calculate their relevance. Both approaches have advantages and disadvantages. Download methodologies are more effective but they pose a significant overhead on the process in terms of time and bandwidth. Approaches that rely solely on estimation on the other hand, usually depend on document relevance scores being reported by the remote collections in order to achieve maximum performance. In addition to that, regression algorithms, which have proved to be more effective than weighted scores merging algorithms, need a significant number of overlap documents in order to function effectively, practically requiring multiple interactions with the remote collections. The new algorithm that is introduced is based on adaptively downloading a limited, selected number of documents from the remote collections and estimating the relevance of the rest through regression methodologies. Thus it reconciles the above two approaches, combining their strengths, while minimizing their drawbacks, achieving the limited time and bandwidth overhead of the estimation approaches and the increased effectiveness of the download. The proposed algorithm is tested in a variety of settings and its performance is found to be significantly better than the former, while approximating that of the latter. 相似文献
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Dimitrios Challoumas Georgios Dimitrakakis 《Sports biomechanics / International Society of Biomechanics in Sports》2017,16(3):325-341
Infraspinatus atrophy (IA) is much more prevalent in overhead sports compared with the general population. Its exact aetiology in this group of athletes remains unclear and definitive associations with pathology and performance have not yet been reached. The aim of this systematic review is to present the evidence on IA in overhead athletes focussing on the proposed mechanisms of suprascapular neuropathy and its associations with shoulder pathology and performance. A thorough literature search via Medline, EMBASE and Scopus was performed. From the nine articles identified, the majority of authors propose suprascapular nerve (SN) injury at the spinoglenoid notch; however, the suprascapular notch has also been suggested as a potential site of injury. With regard to the exact mechanism of suprascapular neuropathy, the majority of authors propose repeated traction of the nerve during extreme shoulder abduction and horizontal adduction and/or eccentric contractions of the infraspinatus. In the limited relevant literature, convincing links between IA and performance or shoulder pathology have not been identified. IA in overhead sports is most likely of multi-factorial aetiology. Important questions about IA and its significance in overhead sports remain unanswered and more biomechanical and prospective studies are warranted to provide further insights into this athletic injury. 相似文献
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Niaz Mansoor Abd-El-Khalick Fouad Benarroch Alicia Cardellini Liberato Laburú Carlos E. Marín Nicolás Montes Luis A. Nola Robert Orlik Yuri Scharmann Lawrence C. Tsai Chin-Chung Tsaparlis Georgios 《Science & Education》2003,12(8):787-797
This commentary is a critical appraisal of Gil-Pérez et al.'s (2002) conceptualization of constructivism. It is argued that the following aspects of their presentation are problematic: (a) Although the role of controversy is recognized, the authors implicitly subscribe to a Kuhnian perspective of `normal' science; (b) Authors fail to recognize the importance of von Glasersfeld's contribution to the understanding of constructivism in science education; (c) The fact that it is not possible to implement a constructivist pedagogy without a constructivist epistemology has been ignored; and (d) Failure to recognize that the metaphor of the `student as a developing scientist' facilitates teaching strategies as students are confronted with alternative/rival/conflicting ideas. Finally, we have shown that constructivism in science education is going through a process of continual critical appraisals. 相似文献
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Higher and lower-order cognitive skills: The case of chemistry 总被引：2，自引：0，他引：2
A major driving force in the current effort to reform science education is the conviction that it is vital for our students
to develop their higher-order cognitive skills capacity in order to function effectively in our modem, complex science and
technology-based society. In line with this rationale, this study focuses on the use of examinations for studying student
performance in chemistry examination on items that require higher-order cognitive skills (HOCS) or lower-order cognitive skills
(LOCS). This usage of examinations is explored and demonstrated via “post-factum” data analysis of two case studies: the General
Examination (in chemistry) and the Panhellenic Chemistry Competition administered natinally in Greece for secondary-school
graduates in 1991. The main findings were: (a) students performed considerably lower on questions requiring HOCS than on those
requiring LOCS; (b) performance on questions requiring HOCS may not correlate with that on questions requiring LOCS for which
affective factors, LOCS-orientation in teaching and the extent of prior examination preparation may be responsible; and (c)
examinations that contain intems of both types can be effectively used to identify HOCS- and LOCS- students within various
contexts of chemistry teaching. Based on the above and previous related studies, the fostering of students' HOCS by appropriate
teaching and assessment trategies is advocated. 相似文献
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Why are students with LD depressed? A goal orientation model of depression vulnerability 总被引：1，自引：0，他引：1
Sideridis GD 《Journal of learning disabilities》2007,40(6):526-539
The thesis of the present study was that failure in achievement tasks may constitute a stress factor that can trigger a depression episode, particularly for students with learning disabilities (LD), and that a particular motivational pattern may constitute a cognitive diathesis for depression. Participants were 104 students referred for LD who were drawn from a pool of approximately 900 students from Grades 5 and 6. Students were challenged with a series of difficult math exercises, and their achievement behaviors were examined as a function of achievement goal orientations. Results from structural equation modeling provided empirical support of the contention that performance-avoidance goals may account for a series of negative cognitions and affect. Direct positive paths linked performance-avoidance goals to anxiety, depression, and negative affect; negative paths were revealed with regard to self-esteem and positive affect. Thus, performance-avoidance goals may possess elements of the diathesis mechanism described by Dykman, constituting a vulnerability factor that triggers the mechanism of depression when negative events are in place. 相似文献
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Sideridis GD 《Journal of learning disabilities》2002,35(4):343-356
The purpose of this study was to compare the motivational determinants of students at risk of language difficulties (in reading and spelling) and students with high language skills. Teachers' evaluations in language and mathematics at the end of the academic year constituted the dependent variable. Motivational orientations were examined using the constructs that reflect the theory of planned behavior and goal importance. Participants were 202 elementary school students-22 at risk of language difficulties and 180 with high language skills-drawn from 30 elementary schools in northern Greece. The results indicated that the two groups differed significantly, with the at-risk students exhibiting significantly lower perceptions of goal importance, intention to achieve, belief strength, outcome evaluation, and normative beliefs, and eventually scoring lower in language and mathematics at the end of the academic year. A finer analysis of students' motivational orientations was conducted using covariance structural modeling (CSM) and EQS 5.7b. The planned behavior model with goal importance produced a comparative fit index (CFI) of 1.00 in language and mathematics for the at-risk group. The respective CFIs for the high language skills group were .97 and 1.00 in language and mathematics, respectively. Although model fit was excellent across samples, different weights and signs linking motivational orientations to achievement partly explained the observed differences in language and mathematics manifested in the two groups. 相似文献
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Dimitrios Tsolis Spyros Sioutas Michalis Nik Xenos Georgios Styliaras 《Journal of Cultural Heritage》2011,12(4):466
As a general and effective protection measure for copyright violations, which occur with the use of digital technologies including peer-to-peer (P2P) networks, copyright owners from the cultural sector often use Digital Rights Management (DRM) systems and digital watermarking techniques so as to encrypt copyright information to the cultural content. In other cases, copyright owners restrict or even block access to the digital cultural content through the Internet and the P2P infrastructure. This chapter claims that DRM and P2P can be quite complementary. Specifically, a P2P infrastructure is presented which allows broad digital cultural content exchange while on the same time supports copyright protection and management through watermarking technologies for digital images. 相似文献