A study of untrained models for multimodal information retrieval     

Melanie?ImhofEmail authorView author&#;s OrcID profile  Martin?Braschler 《Information Retrieval》2018,21(1):81-106

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   

Project Management Techniques at the Complutense University: Academic Librarians' Perceptions     

Silvia Cobo Serrano  Rosario Arquero Avilés 《New Review of Academic Librarianship》2018,24(2):124-135

This study examines how academic librarians at the Complutense University (Spain) perceive project management techniques that are becoming increasingly popular in library and information centers due to the need to comply with their strategic planning and services. To reach this goal, a quantitative and qualitative methodology was applied and a survey, in the form of a questionnaire, was used as a data gathering tool. The response rate was 31.2%. The key findings are based on respondents' education regarding project management skills and their expertise managing projects, as well as the presence of project management courses in the Library and Information Science Spanish curriculum. This study revealed that over one third of the academic staff completed their project management training by self-directed learning. Additionally, over half of them stated that they had not participated in any library project in the last five years, and almost half of the library staff concluded that project management techniques are quite important as formal courses in the Library and Information Science university programs. The study is interesting and revealing for those library and information services professionals who are facing day-to-day to users' demands and Library and Information Science challenges.  相似文献   

The Promise of the Transparency Culture     

Ester Appelgren  Ramón Salaverría 《Journalism Practice》2018,12(8):986-996

In 2013, with the introduction of the Transparency Law in Spain, a number of Spanish newsrooms started working with data journalism methods. In Sweden, which has one of the oldest Freedom of Information acts in the world, newsrooms invested in the skill development of data journalism at approximately the same time. Because previous research suggests that access to public data has been one of the key driving forces for the development of data journalism worldwide, it is important to understand how legislation is actually shaping the practice of data journalism. Based on a survey of 66 key informants in Spain and Sweden and ten in-depth interviews with data journalists from five media companies in each country, we conducted a comparative study, building on the frameworks of media systems to explore data journalism practices in these two countries. The differences found indicate that the national and EU legislation in both nations shape journalistic strategies for accessing data, turning journalists at times into activists fighting for the right to access public data. Beyond the law, data journalists advocate for a transparency culture among the civil servants, in order to secure public accountability.  相似文献   

Correction to: A probabilistic approach to student workload: empirical distributions and ECTS     

Antonio Souto-Iglesias  María Teresa Baeza_Romero 《Higher Education》2018,76(6):1027-1027

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Academic Libraries and Copyright: Unveiling Inadequacies of Current Law Through the Analysis of Processes Included in Quality Management Systems     

Juan-Carlos Fernández-Molina  Margarita Pérez-Pulido  José-Luis Herrera-Morillas 《The Journal of Academic Librarianship》2017,43(3):184-192

Most information resources that make up university library collections are copyrighted works, which means that conflicts between such rights and the activities of libraries are common. The development of the digital setting has affected both sectors. On the one hand, it has led to changes in copyright legislation; on the other, it has affected the services provided by libraries, as they adapt to the new needs of users and to the characteristics of digital information. This paper aims to discover where the main points of collision between the two sides lie, and to what extent they are adequately resolved by the present legislation governing copyright. To this end we use a list of the main processes of academic libraries taken from quality manuals of a sample of Spanish university libraries. The results make manifest that the evolution of both sides is not yet balanced, and important maladjustments interfere with an adequate provision of services in academic libraries. Some are resolved through new legal proposals, but for many others there is no proper solution in sight.  相似文献   

On the relationship between society and higher education: what path should we take?     

Laura Márquez-Ramos  Estefanía Mourelle 《Distance Education》2018,39(1):19-36

Abstract

The current network society, with its primacy of information and communication technologies, is challenging the higher education model. The needs and expectations of today’s students differ from those of students in the past, and educational practices should adapt to modern times. But what changes will we see in the relationship between societal transformation and the higher education system? In this research paper, we set out a quantum-based approach in order to analyze this relationship and to advance the understanding about the role that distance education will play in the future. Under this perspective, we provide an illustration that allows for the representation and evaluation of future scenarios.  相似文献   

The role of index compression in score-at-a-time query evaluation     

Jimmy?Lin  Andrew?TrotmanEmail authorView author&#;s OrcID profile 《Information Retrieval》2017,20(3):199-220

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   

Identifying top relevant dates for implicit time sensitive queries     

Ricardo?CamposEmail authorView author&#;s OrcID profile  Ga?l?Dias  Alípio?Mário?Jorge  Célia?Nunes 《Information Retrieval》2017,20(4):363-398

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   

Statistical biases in Information Retrieval metrics for recommender systems     

Alejandro?BellogínEmail authorView author&#;s OrcID profile  Pablo?Castells  Iván?Cantador 《Information Retrieval》2017,20(6):606-634

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   

The orchestration of a collaborative information seeking learning task     

Simon?KnightEmail authorView author&#;s OrcID profile  Bart?Rienties  Karen?Littleton  Dirk?Tempelaar  Matthew?Mitsui  Chirag?Shah 《Information Retrieval》2017,20(5):480-505

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