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11.
This article argues that most contemporary children’s environmental picture books and easy readers published in the United States focus overwhelmingly on individual environmentalist acts and lifestyle changes, overlook the connections between environmental degradation and systemic social problems such as class disparities, and ultimately over-simplify environmental crisis. They typically encourage children to adopt environmentalist behaviors such as recycling that can be performed by individuals or families in the home, school, and local community, but do little to encourage civic engagement that would call into attention the intertwined ideological, economic, and political factors preventing profound environmental change. The analysis then examines several books that notably do inform readers about the larger political and economic issues and place a strong emphasis on environmental justice, a type of environmentalism deeply concerned with issues of race, class, gender, and economic inequality. Such texts are more likely to encourage an environmentalism that combines lifestyle and consumer choices with political activism. We need more books like this, as children’s texts that resign environmental action almost completely to individual choices and behaviors and disassociate environmental crises from their larger constitutive contexts do little to prepare young people for the socio-environmental challenges we face now and in the future.  相似文献   
12.
Operational multimodal information retrieval systems have to deal with increasingly complex document collections and queries that are composed of a large set of textual and non-textual modalities such as ratings, prices, timestamps, geographical coordinates, etc. The resulting combinatorial explosion of modality combinations makes it intractable to treat each modality individually and to obtain suitable training data. As a consequence, instead of finding and training new models for each individual modality or combination of modalities, it is crucial to establish unified models, and fuse their outputs in a robust way. Since the most popular weighting schemes for textual retrieval have in the past generalized well to many retrieval tasks, we demonstrate how they can be adapted to be used with non-textual modalities, which is a first step towards finding such a unified model. We demonstrate that the popular weighting scheme BM25 is suitable to be used for multimodal IR systems and analyze the underlying assumptions of the BM25 formula with respect to merging modalities under the so-called raw-score merging hypothesis, which requires no training. We establish a multimodal baseline for two multimodal test collections, show how modalities differ with respect to their contribution to relevance and the difficulty of treating modalities with overlapping information. Our experiments demonstrate that our multimodal baseline with no training achieves a significantly higher retrieval effectiveness than using just the textual modality for the social book search 2016 collection and lies in the range of a trained multimodal approach using the optimal linear combination of the modality scores.  相似文献   
13.
This paper explores the performance of top k document retrieval with score-at-a-time query evaluation on impact-ordered indexes in main memory. To better understand execution efficiency in the context of modern processor architectures, we examine the role of index compression on query evaluation latency. Experiments include compressing postings with variable byte encoding, Simple-8b, variants of the QMX compression scheme, as well as a condition that is less often considered—no compression. Across four web test collections, we find that the highest query evaluation speed is achieved by simply leaving the postings lists uncompressed, although the performance advantage over a state-of-the-art compression scheme is relatively small and the index is considerably larger. We explain this finding in terms of the design of modern processor architectures: Index segments with high impact scores are usually short and inherently benefit from cache locality. Index segments with lower impact scores may be quite long, but modern architectures have sufficient memory bandwidth (coupled with prefetching) to “keep up” with the processor. Our results highlight the importance of “architecture affinity” when designing high-performance search engines.  相似文献   
14.
Despite a clear improvement of search and retrieval temporal applications, current search engines are still mostly unaware of the temporal dimension. Indeed, in most cases, systems are limited to offering the user the chance to restrict the search to a particular time period or to simply rely on an explicitly specified time span. If the user is not explicit in his/her search intents (e.g., “philip seymour hoffman”) search engines may likely fail to present an overall historic perspective of the topic. In most such cases, they are limited to retrieving the most recent results. One possible solution to this shortcoming is to understand the different time periods of the query. In this context, most state-of-the-art methodologies consider any occurrence of temporal expressions in web documents and other web data as equally relevant to an implicit time sensitive query. To approach this problem in a more adequate manner, we propose in this paper the detection of relevant temporal expressions to the query. Unlike previous metadata and query log-based approaches, we show how to achieve this goal based on information extracted from document content. However, instead of simply focusing on the detection of the most obvious date we are also interested in retrieving the set of dates that are relevant to the query. Towards this goal, we define a general similarity measure that makes use of co-occurrences of words and years based on corpus statistics and a classification methodology that is able to identify the set of top relevant dates for a given implicit time sensitive query, while filtering out the non-relevant ones. Through extensive experimental evaluation, we mean to demonstrate that our approach offers promising results in the field of temporal information retrieval (T-IR), as demonstrated by the experiments conducted over several baselines on web corpora collections.  相似文献   
15.
There is an increasing consensus in the Recommender Systems community that the dominant error-based evaluation metrics are insufficient, and mostly inadequate, to properly assess the practical effectiveness of recommendations. Seeking to evaluate recommendation rankings—which largely determine the effective accuracy in matching user needs—rather than predicted rating values, Information Retrieval metrics have started to be applied for the evaluation of recommender systems. In this paper we analyse the main issues and potential divergences in the application of Information Retrieval methodologies to recommender system evaluation, and provide a systematic characterisation of experimental design alternatives for this adaptation. We lay out an experimental configuration framework upon which we identify and analyse specific statistical biases arising in the adaptation of Information Retrieval metrics to recommendation tasks, namely sparsity and popularity biases. These biases considerably distort the empirical measurements, hindering the interpretation and comparison of results across experiments. We develop a formal characterisation and analysis of the biases upon which we analyse their causes and main factors, as well as their impact on evaluation metrics under different experimental configurations, illustrating the theoretical findings with empirical evidence. We propose two experimental design approaches that effectively neutralise such biases to a large extent. We report experiments validating our proposed experimental variants, and comparing them to alternative approaches and metrics that have been defined in the literature with similar or related purposes.  相似文献   
16.
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17.
Radiation dose monitoring has become an essential service that hospitals must perform. Depending on the system in place, this can result in the collection of large quantities of data, ripe for analysis. These data should include a wide variety of variables for each study because assessment of the propriety of the patient’s dose is dependent on many factors, including patient age and size, as well as the body section that is being scanned. Moreover, the scanners themselves have many properties that affect patient dose, such as model, pitch and kVp. In this paper, we propose an engine that seamlessly integrated with a clinical PACS to retrieve radiation dosage data. We devised several schemes to analyze these data through visualization and mining techniques that examine it at different scopes. We demonstrate the utility of such visual methods at examining large, noisy, and multi-dimensional data, which is embodied in the collected radiation data.  相似文献   
18.
The aim of this study is to design and implement a digital interactive globe system (DIGS), by integrating low-cost equipment to make DIGS cost-effective. DIGS includes a data processing unit, a wireless control unit, an image-capturing unit, a laser emission unit, and a three-dimensional hemispheric body-imaging screen. A quasi-experimental study was conducted to evaluate the learning effectiveness of our system. A total of 105 junior high-school students from Taiwan participated in this 8-week experiment. The students were divided into three individual groups of 35 students each, with one control group and two experimental groups (EG1 and EG2). The results of one-way mixed design ANOVA indicated that participants in the experimental group, who used the DIGS, outperformed the other two groups, in the post-test as well as in the delayed test. These findings demonstrate that the proposed DIGS can effectively enhance the performance of the learners in an Earth Science course.  相似文献   
19.
Over the past 20 years, relational theories of leadership have gained increased traction in the global discourse in educational leadership. This is observable in the increased frequency with which scholars have begun to construct leadership within the sociocultural and institutional systems of different societies. This study addressed the question, “How is effective school leadership constructed in the multi-faceted education context of modern day Vietnam?” We employed a multi-site case study research design to collect qualitative data from several stakeholder groups in three Vietnamese schools. Analysis centered on describing and synthesizing how principal leadership was constructed in these settings. This study “contextualized school leadership” by describing how leadership themes of managing relationships, preserving harmony, and teacher empowerment were shaped by institutional, political and socio-cultural forces in Vietnamese society. The findings support the importance of contextualizing leadership in order to understand differences in how “effective school leadership” is constructed and understood across different societies.  相似文献   
20.
ABSTRACT

Umbrella action research projects link together a number of small action research projects under a common organizational and thematic umbrella. This article provides an example of an umbrella action research project, which aimed for teaching quality enhancement. There are two mechanisms by which teaching quality can be enhanced. The first of these is through the improvements initiated in the small projects, which are normally conducted by teachers in the courses they teach. The second mechanism is that of the collective reflective discussions of the whole project team. The collective umbrella that over-arches the individual projects provides a mechanism for participants to collectively transform their understanding of the common thematic issue. There is, therefore, the possibility of an emancipatory transformation, so that the whole achieves more than the sum of the individual projects. This article substantiates the impact of umbrella action research projects by presenting case studies from an overall project that focused on online learning. The cases highlight our reflective discussions on promoting student engagement in online learning. They show how our collective understanding of engagement in online learning was advanced and some of the means tried in the small projects to encourage student engagement. As there is evidence of teaching quality enhancement through the umbrella action research project, we discuss the possibility of redirecting some of the resources currently devoted to quality assurance to quality enhancement through encouraging action research projects.  相似文献   
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