Situations,interactions, processes and affordances: A response     

Akhras  Fabio N.  Self  John A. 《Instructional Science》2002,30(1):65-69

This is a brief response to thecommentaries provided by Young, DePalma andGarrett and by Azevedo on our original paper(Akhras & Self, this issue). In this responsewe elaborate on the aims of ourconceptualization, focussing on the nature ofaffordances and situations.  相似文献   

Testing the cluster hypothesis in distributed information retrieval     

Fabio Crestani  Shengli Wu 《Information processing & management》2006

How to merge and organise query results retrieved from different resources is one of the key issues in distributed information retrieval. Some previous research and experiments suggest that cluster-based document browsing is more effective than a single merged list. Cluster-based retrieval results presentation is based on the cluster hypothesis, which states that documents that cluster together have a similar relevance to a given query. However, while this hypothesis has been demonstrated to hold in classical information retrieval environments, it has never been fully tested in heterogeneous distributed information retrieval environments. Heterogeneous document representations, the presence of document duplicates, and disparate qualities of retrieval results, are major features of an heterogeneous distributed information retrieval environment that might disrupt the effectiveness of the cluster hypothesis. In this paper we report on an experimental investigation into the validity and effectiveness of the cluster hypothesis in highly heterogeneous distributed information retrieval environments. The results show that although clustering is affected by different retrieval results representations and quality, the cluster hypothesis still holds and that generating hierarchical clusters in highly heterogeneous distributed information retrieval environments is still a very effective way of presenting retrieval results to users.  相似文献   

Hermeneutics and Science Education: The role of history of science     

Fabio Bevilacqua  Enrico Giannetto 《Science & Education》1995,4(2):115-126

Eger's contribution towards a reapprochment of Hermeneutics, Science and Science Education is very welcome. His focus on the problem of misconceptions is relevant. All the same in our opinion some not minor points need a clarification. We will try to argue that: a) Hermeneutics cannot be reduced to a semantical interpretation of science texts; its phenomenological aspects have to be taken in account. b) Science has an unavoidable historical dimension; original papers and advanced textbooks are the real depositaries of scientific research. Standard textbooks are a caricature not worth it of a hermeneutical analysis. c) A parallelism can be traced between two dicothomies: the lifeworld of hermeneutics and the scienceworld of epistemology on one side and the extraordinary and the normal science on the other. d) For an overcoming of the misconceptions' problem we propose that the previous dicothomies be bridged through a hermeneutical phenomenological approach to science education that stresses the alternative, historical interpretations of natural phenomena.  相似文献   

From planning to mature: On the success of open source projects     

Stefano Comino  Fabio M. Manenti  Maria Laura Parisi   《Research Policy》2007,36(10):1575-1586

Open source is an example of user-centric innovation initiated by an individual or group of users to satisfy their specific needs; the more a software evolves towards a stable release able to address the requirements of its developers, the more successful the project. In this paper we use a large data-set obtained from SourceForge.net to estimate the relationship between a series of different characteristics of OS projects and the probability of evolution of the source code from a preliminary release to a mature version. We show that while projects distributed under highly restrictive licensing terms (GPL) have a significantly smaller probability of reaching a stable release, applications towards sophisticated users have a larger probability of evolving in the development status. Interestingly, we find that the size of the “community of developers” increases the chances of progress but this effect decreases as the community gets larger, a signal of possible coordination problems.  相似文献   

Museum Heroes All: The Pavia Approach to School-Science Museum Interactions     

Lidia Falomo Bernarduzzi  Gabriele Albanesi  Fabio Bevilacqua 《Science & Education》2014,23(4):761-780

To improve on the classic school trip to the museum and the traditional distinctions between formal and informal learning, every year we run a project where the schools (first the teachers and then the pupils) are actively involved right from the very first stages of planning. The various projects realised so far involve schools with children of different age levels, from kindergarten to high school, and aim to provide a rewarding museum experience for each level. The various phases of each project follow a timeline where the specific roles of each group of actors is set out. All our projects rely extensively on history of science, but in a number of ways: using primary and secondary sources, museum exhibitions, multimedia and hands-on reconstructions of historical experiments. We mix all these resources together to offer a historical route suitable to the various age groups. Creative analogical thinking, iconographic similarities and coincidences between the scientific and artistic domains are encouraged especially with children from 3 to 13 years old. These comparisons become pretexts for analysis, reflection and creative production also at the graphic level. In this paper we outline our methodology in the specific case of a laboratory and exhibition experience built around the person and work of Galileo. One of the results has been the involvement of the pupils in a new, unexpected emotional experience.  相似文献   

Science Letters: Vascular architecture: is it a helpful histopathological biomarker for hepatocellular carcinoma?     

GRIZZI Fabio  FRANCESCHINI Barbara  FIAMENGO Barbara  RUSSO Carlo  DIOGUARDI Nicola 《Journal of Zhejiang University. Science. B》2007,8(4)

Hepatocellular carcinoma (HCC) remains one of the major public health problems throughout the world. Although originally associated with tumorigenic processes, liver angiogenesis has also been observed in the context of different liver inflammatory, fibrotic, and ischemic conditions. Here we investigate the fractal dimension as a quantitator of non-Euclidean two-dimensional vascular geometry in a series of paired specimens of primary HCC and surrounding non-tumoral tissue, and discuss why this parameter might provide additional information regarding cancer behavior. The application of fractal geometry to the measurement of liver vascularity and the availability of a computer-aided quantitative method can eliminate errors in visual interpretation, and make it possible to obtain closer-to-reality numerals that are compulsory for any measurement process.  相似文献   

Acute passive stretching in a previously fatigued muscle: Electrical and mechanical response during tetanic stimulation     

Fabio Esposito  Emiliano Cè  Susanna Rampichini  Arsenio Veicsteinas 《Journal of sports sciences》2013,31(12):1347-1357

Abstract

The aim of this study was to assess the effects of acute passive stretching on the electrical and mechanical response of a previously fatigued muscle. Eleven participants underwent maximal tetanic stimulations (50 Hz) of the medial gastrocnemius, before and after a fatiguing protocol and after a bout of passive stretching of the fatigued muscle. During contraction, surface electromyography (EMG), mechanomyography (MMG), and force were recorded. The following parameters were calculated: (1) the EMG root mean square (RMS), mean frequency, and fibre conduction velocity; (2) MMG peak-to-peak and RMS; (3) the peak force, contraction time, half-relaxation time, peak rate of force development (dF/dt) and its acceleration (d² F/dt ²). Fatigue reduced peak force by 18% (P < 0.05) and affected the other force, EMG, and MMG parameters. After stretching: (1) all EMG parameters recovered to pre-fatigue values; (2) MMG peak-to-peak remained depressed, while RMS recovered to pre-fatigue values; (3) the peak force, peak rate of force development and its acceleration were further reduced by 22, 18, and 51%, respectively, and half-relaxation time by 40% (P < 0.05). In conclusion, acute passive stretching, when applied to a previously fatigued muscle, further depresses the maximum force-generating capacity. Although stretching does not alter the electrical parameters of the fatigued muscle, it does affect the mechanical behaviour of the muscle–tendon unit.  相似文献   

Preferential text classification: learning algorithms and evaluation measures     

Fabio Aiolli  Riccardo Cardin  Fabrizio Sebastiani  Alessandro Sperduti 《Information Retrieval》2009,12(5):559-580

In many applicative contexts in which textual documents are labelled with thematic categories, a distinction is made between the primary categories of a document, which represent the topics that are central to it, and its secondary categories, which represent topics that the document only touches upon. We contend that this distinction, so far neglected in text categorization research, is important and deserves to be explicitly tackled. The contribution of this paper is threefold. First, we propose an evaluation measure for this preferential text categorization task, whereby different kinds of misclassifications involving either primary or secondary categories have a different impact on effectiveness. Second, we establish several baseline results for this task on a well-known benchmark for patent classification in which the distinction between primary and secondary categories is present; these results are obtained by reformulating the preferential text categorization task in terms of well established classification problems, such as single and/or multi-label multiclass classification; state-of-the-art learning technology such as SVMs and kernel-based methods are used. Third, we improve on these results by using a recently proposed class of algorithms explicitly devised for learning from training data expressed in preferential form, i.e., in the form “for document d _i , category c′ is preferred to category c′′”; this allows us to distinguish between primary and secondary categories not only in the classification phase but also in the learning phase, thus differentiating their impact on the classifiers to be generated.  相似文献   

Sprinting analysis of elite soccer players during European Champions League and UEFA Cup matches   总被引：1，自引：1，他引：0  

Di Salvo V  Baron R  González-Haro C  Gormasz C  Pigozzi F  Bachl N 《Journal of sports sciences》2010,28(14):1489-1494

It has been suggested that assessment of high-intensity activities during a match is a valid measure of physical performance in elite soccer. Recently, sprinting activities have been analysed in more depth. The aim of this study was to develop a detailed analysis of the sprinting activities of different playing positions during European Champions League and UEFA Cup competitions. Altogether, 717 elite outfield soccer players were evaluated throughout 2002-2006 using ProZone? (Leeds, UK). Sprinting (explosive and leading) was analysed for each playing position. To compare positional differences, a Kruskal-Wallis analysis was performed. Differences were found among positions for total number of sprints and total sprint distance covered: wide midfielders > (attackers = wide defenders) > central midfielders > central defenders (P < 0.001), as well as for explosive sprints: (wide midfielders = attackers = wide defenders) > central defenders, wide midfielders > central midfielders > central defenders and attackers = wide defenders = central midfielders (P < 0.001), and leading sprints: wide midfielders > (attackers = wide defenders) > central midfielders > central defenders (P < 0.001). For each group, there were no differences in ratio of explosive to leading sprints. Wide midfielders performed a higher number of sprints in all five distance categories than all other positions. This study showed that sprinting characteristics are influenced by position. Wide midfielders have to complete additional high-intensity activities during training sessions compared with the other positions to achieve the performance level required during the match.  相似文献   

The history of physics and European physics education     

Fabio Bevilacqua  Enrico Giannetto 《Science & Education》1996,5(3):235-246

In the last fifteen years a small group of European physicists has been working towards an approach to physics education based on the actual practices of physics research. The standard presentation through traditional textbooks plus didactic laboratory is rejected, and instead case studies contributing and borrowing from contemporary history, philosophy and sociology of science are provided. Analysis of original papers, scientific debates, institutional settings are often accompanied by reconstructions of important historical instruments. The resulting interplay between theories, instruments and experimental results offers a view of physics fascinating and entertaining, closer to the actual scientists' activities, deprived of many traditional ideological assumptions, open to the students interpretations and often in tune with contemporary findings of science educators. The group's activities are quietly flourishing, have acquired institutional recognition in the European Physical Society, and are now coordinated with the ones organized around the journal Science & Education and the International History, Philosophy and Science Teaching Group.  相似文献