1,721,057 research outputs found
P-Hera : Scalable fine-grained access control for P2P infrastructures
No full textIn this paper, we present P-Hera, a peer-to-peer (P2P) infrastructure for scalable and secure content hosting. P-Hera allows the users and content owners to dynamically establish trust using fine-grained access control. In P-Hera, resource owners can specify fine-grained restrictions on who can access their resources and which user can access which part of data. We differentiate our work with traditional works of fine-grained access control on Web services, as our system in addition to handling access constrains of the service provider (which is the case in Web services), it also handles security constrains regarding actions performed on data: replication and modification. We believe this is of immense significance for wide-range of applications such as data Grids, Information Grids and Web Content Delivery Networks. In addition to presenting the over-all system architecture, we also study the problem of evaluating these fine-grained access policies in depth and propose a novel means of organizing these policies that can result in faster evaluation. We demonstrate the effectiveness of our approach using prototype implementation
Efficent Integration of Fine-grained Access Control in Large-scale Grid Services
No full textIn this paper, we present a scalable authorization service, based on the concept of fine-grained access control (FGAC), for large-scale Grid infrastructures that span multiple independent domains. FGAC enables participating resource owners to specify fine-grained policies concerning which user can access can their resources under which mode. We argue that such an authorization service must be integrated with the resource broker service to avoid scheduling requests onto resources which do not authorize the user request. For this reason, we develop a novel resource broker service that integrates access control with resource scheduling. In our system, both resource owners and users define their resource access and usage policies. The resource broker schedules a user request only within the set of resources whose policies match the user credentials (and vice-versa). Since this process of evaluating authorization policies of resources and user, in addition to checking the resource requirement, can be a potential bottleneck for a large scale Grid, we also analyze the problem of efficient evaluation of FGAC policies. In this context, we present a novel method for policy organization and compare its performance with other strategies. Preliminary results show that the proposed method can significantly enhance performance
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Variations on the Author
Get PDF“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
Get PDFWe 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
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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