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We present a term weighting approach for improving web page classification, based on the assumption that the images of a web page are those elements which mainly attract the attention of the user. This assumption implies that the text contained in the visual block in which an image is located, called image-block, should contain significant information about the page contents. In this paper we propose a new metric, called the Inverse Term Importance Metric, aimed at assigning higher weights to important terms contained into important image-blocks identified by performing a visual layout analysis. We propose different methods to estimate the visual image-blocks importance, to smooth the term weight according to the importance of the blocks in which the term is located. The traditional TFxIDF model is modified accordingly and used in the classification task. The effectiveness of this new metric and the proposed block evaluation methods have been validated using different classification algorithms. 相似文献
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F. Mori R. Ponti A. Messina M. Flieger V. Havlicek M. Sinibaldi 《Journal of Cultural Heritage》2006,7(4):344-349
The analysis of the amino acid (AA) content in fragments derived from a prehistoric rock pictograph (Lancusi rock shelter) at Tadrart Acacus, southern west Libya, revealed the presence of material containing peptides differing in solubility in hot acidic or alkaline solutions, as well as in AA composition and racemization. Water-soluble components were constituted of low molecular weight peptides with high racemization of aspartic acid and alanine, whereas the water insoluble material consisted of species of a more complex AA composition and a different degree of racemization. The proteinaceous materials were assumed to originate from matter that had undergone over time different diagenetic processes. The water insoluble peptide-containing material was separated from the rock substrate by acid hydrolysis, dried and the resulting residue submitted to radiocarbon analysis. Accelerator mass spectrometry (AMS) yielded an approximate age of 6145 ± 70 years B.P. (before present), which is consistent with archaeological inference and the climatic reconstruction of central Sahara. To our knowledge the present work represents the first attempt of direct radiocarbon dating of rock art in the Sahara desert. 相似文献
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The use of digital tools like computers and tablets in institutional learning arenas give rise to forms of flexibility where time and space boundaries become diffuse. Online learning sites are understood as being crucial today, especially in large parts of the Global North, where anyone anywhere potentially can become a student and have access to educational opportunities.This study focuses on the analysis of recorded sessions, part of an ‘Italian for (adult) beginners' online course. Our interests relate to accounting for how students negotiate different language varieties, including modalities, and how communication in virtual learning settings enables both flexible participation trajectories and identity positions in and across the boundaries of time and space.The sociocultural and dialogical analyses here are framed in terms of fluidity of ‘glocal' positions and (trans)languaging that emerge in and across time and space in Technology Mediated Communication. Our findings suggest that online environments support meaning-making where it is possible to identify alternative ways of (co)constructing and mediating learning. Such hybridity as well as the performative character of learning and identity display have important implications for online glocal communities. 相似文献
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Much of the valuable information in supporting decision making processes originates in text-based documents. Although these documents can be effectively searched and ranked by modern search engines, actionable knowledge need to be extracted and transformed in a structured form before being used in a decision process. In this paper we describe how the discovery of semantic information embedded in natural language documents can be viewed as an optimization problem aimed at assigning a sequence of labels (hidden states) to a set of interdependent variables (textual tokens). Dependencies among variables are efficiently modeled through Conditional Random Fields, an indirected graphical model able to represent the distribution of labels given a set of observations. The Markov property of these models prevent them to take into account long-range dependencies among variables, which are indeed relevant in Natural Language Processing. In order to overcome this limitation we propose an inference method based on Integer Programming formulation of the problem, where long distance dependencies are included through non-deterministic soft constraints. 相似文献
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Graciela Messina Raúl Valdés-Cotera 《International Review of Education/Internationale Zeitschrift für Erziehungswissenschaft/Revue internationale l'éducation》2013,59(4):425-441
This article considers the development of educating cities from a political perspective, illustrating in detail the diversity of organisations and individuals involved and the challenges they are facing. Bearing in mind that educating cities were established from the 1990s onwards in Europe and spread to other continents from there, the purpose of this article is to demonstrate how this proposal was adopted in Latin America. After discussing the basic aims of educating cities, the paper focuses on the Latin American experience, giving examples of existing projects within the educating cities initiative. The authors are particularly interested in the contrast between the political intentions of educating cities on the one hand and the social, economic, political and cultural world on the other hand. They observe that in this context there is a danger of the individual being forgotten, which contradicts the actual intention of the educating city concept. They also discuss the problem of who should carry out the realisation of educating cities and how the various stakeholders might coordinate their actions. Contemplating new directions at the end of their paper, the authors sum up a number of guidelines and offer recommendations for action in developing educating cities. 相似文献
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This paper studies the incidence and consequences of the mismatch between formal education and the educational requirements of jobs in Estonia during the years 1997–2003. We find large wage penalties associated with the phenomenon of educational mismatch. Moreover, the incidence and wage penalty of mismatches increase with age. This suggests that structural educational mismatches can occur after fast transition periods. Our results are robust for various methodologies, and more importantly regarding departures from the exogeneity assumptions inherent in the matching estimators used in our analysis. 相似文献
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Jianwei Zhang Marlene Scardamalia Mary Lamon Richard Messina Richard Reeve 《Educational technology research and development : ETR & D》2007,55(2):117-145
This study examines four months of online discourse of 22 Grade 4 students engaged in efforts to advance their understanding
of optics. Their work is part of a school-wide knowledge building initiative, the essence of which is giving students collective
responsibility for idea improvement. This goal is supported by software—Knowledge Forum—designed to provide a public and collaborative
space for continual improvement of ideas. A new analytic tool—inquiry threads—was developed to analyze the discourse used
by these students as they worked in this environment. Data analyses focus on four knowledge building principles: idea improvement; real ideas, authentic problems (involving concrete/empirical and abstract/conceptual artifacts); community knowledge (knowledge constructed for the benefit of the community as a whole); and constructive use of authoritative sources. Results indicate that these young students generated theories and explanation-seeking questions, designed experiments to
produce real-world empirical data to support their theories, located and introduced expert resources, revised ideas, and responded
to problems and ideas that emerged as community knowledge evolved. Advances were reflected in progress in refining ideas and
evidence of growth of knowledge for the community as a whole. Design strategies and challenges for collective idea improvement
are discussed.
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| Jianwei ZhangEmail: |
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The aim of this article is to study the possible influence that exercising a representative role at school may have on secondary school students’ willingness to participate politically in society. In order to do this, an analysis was carried out of the answers given by 300 students between 13 and 18 years old, from a school with marked democratic practices, when asked about their experience of democracy at school and their intention to participate politically. The results show that students’ willingness to participate in society by means of conventional actions, such as voting, does not depend directly on whether they have exercised a representative role at school. However, non-conventional actions, such as attending demonstrations or supporting boycotts, does have a meaningful relation with the exercise of representative roles in the school. As a conclusion, we highlight that participating in the representation of the school influences the democratic formation of students and their willingness to participate politically in society, although this influence is more closely related to non-conventional actions, such as strikes, boycotts and demonstrations. 相似文献