1,720,969 research outputs found
Social Media for Social Good: Models and Algorithms
No full textSocial media employ algorithms to promote content that their users would find interesting, so as to maximize user engagement. Therefore they act as a lens, through which an individual looks at reality, or a "filter". These filters create alternative "digital realities" for participants of social networks. A "filter bubble" refers to the state of ideological isolation resulting from social media personalization algorithms. In this thesis we propose approaches to algorithmically break these filter bubbles.
In order to successfully break filter bubbles we come up with methods to detect them, and characterize their strength. First, we look at measuring polarization of opinions, which is a typical manifestation of a filter bubble. Our approach is based on a well-known opinion formation model, and is based on characterizing the random-walk distance of all individuals to the two opposing opinions present in the polarized discussion. We then turn our focus to signed networks, where relationships are characterized by friendship or enmity. We aim to find the maximum possible partition of the graph into two opposing hostile factions. Then, in another line of work, comprising of two papers, we look at measuring the diversity of the exposure of individuals to different opinions. In the first paper, we look at the difference of the values describing information exposure, across all edges in a social graph. In the second, we measure diversity with respect to a model of news item propagation in a network, based on a variant of the well-studied independent cascade model.
Subsequently, we propose algorithmic interventions to break filter bubbles, based on the aforementioned measures of polarization and diversity of exposure. Regarding polarization, we consider the task of moderating the opinions of a small subset of individuals in order to minimize polarization. With respect to diversity of exposure, we consider it a beneficial quantity, which should be maximized. Therefore, we consider the problem of maximizing the diversity index, by changing the exposure of a small subset of individuals to the opposite one. Regarding the "lack of diversity of exposure", we define a function to be maximized, that contains its negation. The resulting maximization problem consists of selecting a small subset of individuals to share a set of news articles in their network, starting multiple parallel cascades. Finally, we examine a different type of intervention that does not directly optimize any measure. We organically increase the number of edges in a network, by leveraging the strong triadic closure property, a well known principle from sociology. Given this property, we ask the question "which friendships should be converted from weak to strong in order to maximize the potential for new edges?".
For all proposed problems we present a complexity analysis, and in most cases, we offer performance guarantees. We evaluate our methods on real-life social networks and we compare them against some baselines
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
Detecting coordinated online behaviour — A multiplex network approach
No full textGiven the impact of online content on individuals’ opinions and attitudes, early detection of online coordinated activities plays a vital role in mitigating the influence of disinformation and information manipulation. Recent research demonstrates that information operations and astroturfing campaigns exhibit distinguishing characteristics related to the temporal proximity and similarity of actions performed by coordinating individuals.
This Thesis extends existing methods by introducing a multiplex network approach and by enhancing Newman collaboration model with a temporal dimension to represent latent coordination. The evaluation of the proposed approach on a range of simulated campaigns demonstrates that detectability significantly improves when considering multiple layers or dimensions of coordination and when modeling the significance of the inter-activity times between users. Notably, both recall and F1 metrics exhibit substantial improvements compared to monoplex approaches found in the current literature.
In particular, based on the F1 scores, the proposed approach is able to outperform traditional methods that rely solely on counting co-occurrences without considering the temporal dimension. Even more crucially, the proposed time-aware model can achieve high recall even on sophisticated coordinated operations, surpassing methods that employ fixed-size time windows. This is especially significant for campaigns that span extended time intervals, up to several days, where malicious accounts strategically alternate between activities and pauses.
These findings not only contribute to a deeper understanding of the challenges in coordination detection but also hold significant implications for the creation of more effective tools and strategies to safeguard the integrity of online discourse
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
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
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