1,721,029 research outputs found
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
A System for the Detection of Limited Visibility in BGP
Full text linkThe performance of the global routing system is vital to thousands of entities operating the Autonomous Systems (ASes) which make up the Internet. The Border Gateway
Protocol (BGP) is currently responsible for the exchange of reachability information and the selection of paths according to their specified routing policies. BGP thus enables traffic to flow from any point to another connected to the Internet. The manner traffic flows is often influenced by entities in the Internet according to their preferences. The latter are implemented in the form of routing policies by tweaking BGP configurations. Routing policies are usually complex and aim to achieve a myriad goals, including technical, economic and political purposes. Additionally, individual network managers need to
permanently adapt to the interdomain routing changes and, by engineering the Internet traffic, optimize the use of their network.
Despite the flexibility offered, the implementation of routing policies is a complicated process in itself, involving fine-tuning operations. Thus, it is an error-prone task and operators might end up with faulty configurations that impact the efficacy of their strate-
gies or, more importantly, their revenues. Withal, even when correctly defining legitimate routing policies, unforeseen interactions between ASes have been observed to cause important disruptions that affect the global routing system. The main reason behind this resides in the fact that the actual inter-domain routing is the result of the interplay of many routing policies from ASes across the Internet, possibly bringing about a different
outcome than the one expected.
In this thesis, we perform an extensive analysis of the intricacies emerging from the complex netting of routing policies at the interdomain level, in the context of the current operational status of the Internet. Abundant implications on the way traffic flows in the Internet arise from the convolution of routing policies at a global scale, at times resulting in ASes using suboptimal ill-favored paths or in the undetected propagation of configuration errors in the routing system. We argue here that monitoring prefix visibility at the interdomain level can be used to detect cases of faulty configurations or backfired routing policies, which disrupt the functionality of the routing system. We show that the lack of global prefix visibility can offer early warning signs for anomalous events which,
despite their impact, often remain hidden from state of the art tools. Additionally, we show that such unintended Internet behavior not only degrades the efficacy of the routing policies implemented by operators, causing their traffic to follow ill-favored paths, but can also point out problems in the global connectivity of prefixes.
We further observe that majority of prefixes suffering from limited visibility at the interdomain level is a set of more-specific prefixes, often used by network operators to
fulfill binding traffic engineering needs. One important task achieved through the use of routing policies for traffic engineering is the control and optimization of the routing function in order to allow the ASes to engineer the incoming traffic. The advertisement of more-specific prefixes, also known as prefix deaggregation, provides network operators with a fine-grained method to control the interdomain ingress traffic, given that the longest-prefix match rule over-rides any other routing policy applied to the covering less specific prefixes.
Nevertheless, however efficient, this traffic engineering tool comes with a cost, which is usually externalized to the entire Internet community. Prefix deaggregation is a known reason for the artificial inflation of the BGP routing table, which can further affect the
scalability of the global routing system. Looking past the main motivation for deploying deaggregation in the first place, we identify and analyze here the economic impact of
this type of strategy. We propose a general Internet model to analyze the effect that advertising more-specific prefixes has on the incoming transit traffic burstiness. We show that deaggregation combined with selective advertisements (further defined as strategic deaggregation) has a traffic stabilization side-effect, which translates into a decrease of the transit traffic bill. Next, we develop a methodology for Internet Service Providers (ISPs)
to monitor general occurrences of deaggregation within their customer base. Furthermore, the ISPs can detect selective advertisements of deaggregated prefixes, and thus identify customers which may impact the business of their providers. We apply the proposed methodology on a complete set of data including routing, traffic, topological and billing information provided by an operational ISP and we discuss the obtained results.Telematics EngineeringUniversidad Carlos III de Madrid, Spainpu
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
Game Theory Application to Interdomain Routing
Full text linkThis thesis proposes a game theoretic analysis of interdomain routing. In the two following chapters we try to capture some of the intricacies of the current Internet routing protocol, the Border Gateway Protocol (BGP).
The first chapter of the thesis paper presents a survey of recent adv ances in the application of game theory to model the behaviour of interdomain routing. In these models, the
participants of the interdomain routing game are represented as strategic agents seeking to improve their benefits through the manipulation of the interdomain routing protoco l BGP.
The main results achieved over the last few years in this field include models to an alyze the stability of the interdomain routing and the design of mechanisms that guarantee BGP to be incentive-compatible with or without monetary transfers. However, over the last years, the research community has been deeply concerned about
the scalability issues that the Internet routing is facing. As the Internet popularity grows, so do the network resources needed in order to sustain its worldwide availability. In the second chapter of this thesis we consider a commons model in which the Global Routing
Table (GRT) is a public resource. We use this model to study the economic incentives the ASes have for deaggregating their assigned address blocks. We evaluate the efficiency of the global routing system, the properties of the game equilibria and we examine its relation
to the social welfare point of the considered game setup. We find that the str ategy adopted by the ASes in the interdomain is not an overall optimum strategy and it leads to an inefficient exploitation of the common resource. Therefore, we prove that the GRT, just like any common natural resource, “remorselessly generates tragedy”, following Hardin’s game theoretic analysis on the tragedy of the commons. Finally, we introduce in the model a pricing
mechanism that aims to avoid the tragedy of the Internet routing commons.Telematics EngineeringUniversidad Carlos III de Madrid, Spainpu
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe 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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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