1,722,031 research outputs found
Evaluating the effects of access control policies within NoSQL systems
No full textAccess control is a key service of any data management system. It allows regulating the access to data resources at different granularity levels on the basis of access control models which vary on the protection options they offer. The more powerful is the access control model in terms of protection requirements, the more difficult is for security administrators to understand the effect of a set of access control policies on the protected resources. This is further complicated within schemaless systems, like NoSQL datastores, when fine grained access control policies are specified for data resources characterized by heterogeneous structures. The lack of a reference data model and related manipulation languages exacerbates this issue. To the best of our knowledge, a general approach to evaluate the impact of access control policies on the protected resources within NoSQL systems is still missing. In this paper, we start to fill this void, by proposing a data model agnostic approach, which, starting from schemaless datasets protected by different discretionary access control models, derives a view of the protected resources that points out authorized and unauthorized contents. Experimental results show the approach efficiency even with large datasets
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Elementi di Geotecnica
No full textLa terza edizione di Elementi di Geotecnica introduce i concetti fondamentali della disciplina, con lo scopo di fornire un primo strumento per affrontare i problemi di natura geotecnica e una base per approfondire in seguito le conoscenze acquisite attraverso la consultazione di opere e memorie specializzate.
Il volume è suddiviso in tre parti: la prima tratta le proprietà delle terre e la loro misura; la seconda sviluppa le principali teorie sulla meccanica delle terre; la terza presenta infine l’applicazione di tali basi fisiche e teoriche ai tipici problemi dell’ingegneria geotecnica. Nella stesura delle prime due parti si sono tenuti in considerazione lo sviluppo e l’evoluzione dell’uso delle prove in situ e gli approcci a nuovi modelli di rappresentazione del reale comportamento delle terre. La terza parte è stata ulteriormente ampliata e aggiornata nelle normative e raccomandazioni, negli aspetti progettuali, nelle tecnologie esecutive e nei metodi di controllo
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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