Organized Behavior Classification of Tweet Sets using Supervised Learning Methods

During the 2016 US elections Twitter experienced unprecedented levels of propaganda and fake news through the collaboration of bots and hired persons, the ramifications of which are still being debated. This work proposes an approach to identify the presence of organized behavior in tweets. The Random Forest, Support Vector Machine, and Logistic Regression algorithms are each used to train a model with a data set of 850 records consisting of 299 features extracted from tweets gathered during the 2016 US presidential election. The features represent user and temporal synchronization characteristics to capture coordinated behavior. These models are trained to classify tweet sets among the categories: organic vs organized, political vs non-political, and pro-Trump vs pro-Hillary vs neither. The random forest algorithm performs better with greater than 95% average accuracy and f-measure scores for each category. The most valuable features for classification are identified as user based features, with media use and marking tweets as favorite to be the most dominant.Comment: 51 pages, 5 figure

Questions-Réponses en domaine ouvert (sélection pertinente de documents en fonction du contexte de la question)

Les problématiques abordées dans ma thèse sont de définir une adaptation unifiée entre la sélection des documents et les stratégies de recherche de la réponse à partir du type des documents et de celui des questions, intégrer la solution au système de Questions-Réponses (QR) RITEL du LIMSI et évaluer son apport. Nous développons et étudions une méthode basée sur une approche de Recherche d Information pour la sélection de documents en QR. Celle-ci s appuie sur un modèle de langue et un modèle de classification binaire de texte en catégorie pertinent ou non pertinent d un point de vue QR. Cette méthode permet de filtrer les documents sélectionnés pour l extraction de réponses par un système QR. Nous présentons la méthode et ses modèles, et la testons dans le cadre QR à l aide de RITEL. L évaluation est faite en français en contexte web sur un corpus de 500 000 pages web et de questions factuelles fournis par le programme Quaero. Celle-ci est menée soit sur des documents complets, soit sur des segments de documents. L hypothèse suivie est que le contenu informationnel des segments est plus cohérent et facilite l extraction de réponses. Dans le premier cas, les gains obtenus sont faibles comparés aux résultats de référence (sans filtrage). Dans le second cas, les gains sont plus élevés et confortent l hypothèse, sans pour autant être significatifs. Une étude approfondie des liens existant entre les performances de RITEL et les paramètres de filtrage complète ces évaluations. Le système de segmentation créé pour travailler sur des segments est détaillé et évalué. Son évaluation nous sert à mesurer l impact de la variabilité naturelle des pages web (en taille et en contenu) sur la tâche QR, en lien avec l hypothèse précédente. En général, les résultats expérimentaux obtenus suggèrent que notre méthode aide un système QR dans sa tâche. Cependant, de nouvelles évaluations sont à mener pour rendre ces résultats significatifs, et notamment en utilisant des corpus de questions plus importants.This thesis aims at defining a unified adaptation of the document selection and answer extraction strategies, based on the document and question types, in a Question-Answering (QA) context. The solution is integrated in RITEL (a LIMSI QA system) to assess the contribution. We develop and investigate a method based on an Information Retrieval approach for the selection of relevant documents in QA. The method is based on a language model and a binary model of textual classification in relevant or irrelevant category. It is used to filter unusable documents for answer extraction by matching lists of a priori relevant documents to the question type automatically. First, we present the method along with its underlying models and we evaluate it on the QA task with RITEL in French. The evaluation is done on a corpus of 500,000 unsegmented web pages with factoid questions provided by the Quaero program (i.e. evaluation at the document level or D-level). Then, we evaluate the methodon segmented web pages (i.e. evaluation at the segment level or S-level). The idea is that information content is more consistent with segments, which facilitates answer extraction. D-filtering brings a small improvement over the baseline (no filtering). S-filtering outperforms both the baseline and D-filtering but not significantly. Finally, we study at the S-level the links between RITEL s performances and the key parameters of the method. In order to apply the method on segments, we created a system of web page segmentation. We present and evaluate it on the QA task with the same corpora used to evaluate our document selection method. This evaluation follows the former hypothesis and measures the impact of natural web page variability (in terms of size and content) on RITEL in its task. In general, the experimental results we obtained suggest that our IR-based method helps a QA system in its task, however further investigations should be conducted especially with larger corpora of questions to make them significant.PARIS11-SCD-Bib. électronique (914719901) / SudocSudocFranceF

Learning-by-Concordance (LbC): introducing undergraduate students to the complexity and uncertainty of clinical practice

Background: A current challenge in medical education is the steep exposure to the complexity and uncertainty of clinical practice in early clerkship. The gap between pre-clinical courses and the reality of clinical decision-making can be overwhelming for undergraduate students. The Learning-by-Concordance (LbC) approach aims to bridge this gap by embedding complexity and uncertainty by relying on real-life situations and exposure to expert reasoning processes to support learning. LbC provides three forms of support: 1) expert responses that students compare with their own, 2) expert explanations and 3) recognized scholars’ key-messages.Method: Three different LbC inspired learning tools were used by 900 undergraduate medical students in three courses: Concordance-of-Reasoning in a 1st-year hematology course; Concordance-of-Perception in a 2nd-year pulmonary physio-pathology course, and; Concordance-of-Professional-Judgment with 3rd-year clerkship students. Thematic analysis was conducted on freely volunteered qualitative comments provided by 404 students.Results:  Absence of a right answer was challenging for 1st year concordance-of-reasoning group; the 2nd year visual concordance group found radiology images initially difficult and unnerving and the 3rd year concordance-of-judgment group recognized the importance of divergent expert opinion.Conclusions: Expert panel answers and explanations constitute an example of “cognitive apprenticeship” that could contribute to the development of appropriate professional reasoning processes

‘Citizens’ Attitudes Under Covid19’, a cross-country panel survey of public opinion in 11 advanced democracies

This article introduces data collected in the Citizens’ Attitudes Under Covid-19 Project (CAUCP), which surveyed public opinion throughout the Covid-19 pandemic in 11 democracies between March and December 2020. In this paper, we present a unique cross-country panel survey of citizens’ attitudes and behaviors during a worldwide unprecedented health, governance, and economic crisis. This dataset investigates the behavioral and attitudinal consequences of multifaceted Covid19 crisis across time and contexts. In this paper, we describe the design of the CAUCP and the descriptive features of the dataset; we also present promising research prospects

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Education Through Labor: From the deuxième portion du contingent to the Youth Civic Service in West Africa (Senegal/Mali, 1920s-1960s)

International audienceUnder the French colonial regime, the “second portion” of the military was used as labour brigades, compelled to serve for two years in works of public nature. They were encamped in labor camp and were taught the value of work as well as discipline and basic rules of hygiene. After the independence of the francophone West African countries in 1960, postcolonial leaders in Senegal and Mali try to implement a civil service for the youth in order to offer them basic education. In reality, the civil service appears as a way to control and use the recruits for economic purposes echoing in some extent the former colonial “second portion du contingent.” More broadly, through the analysis of the legacies and continuities, I argue that the postcolonial elites perpetuate the “civilizing mission,” no more for the so-called mise en valeur of the colonies but for the development of the territory

Tomographic diffractive microscopy: towards highresolution 3-D real-time data acquisition, image reconstruction and display of unlabeled samples

Tomographic diffractive microscopy allows for imaging unlabeled specimens, with a better resolution than conventional microscopes, giving access to the index of refraction distribution within the specimen, and possibly at high speed. Principles of image formation and reconstruction are presented, and progresses towards realtime, three-dimensional acquisition, image reconstruction and final display, are discussed

Performance/mathematics: a dramatisation of mathematical methods

This essay conceptualises the notion of performance mathematics in terms of a paradoxical relationship with the constructed notion of truth, which is shared by theatrical and mathematical performance. Specifically, I argue that these two disciplines can and cannot be reconciled with truthfulness. Grounding my comparison on the notion of an axiomatic method common to both disciplines, I argue that theatrical and mathematical performance can speak of truths only when these truths are properly staged or methodologically grounded according to the internal rules and conditions laid out by each discipline. But in the same way that these truths can be constructed, or they can be done, so they can be undone. Arguing that mathematics can be described as a performance of specific outcomes involving abstract objects and functions, I trace a cross-disciplinary comparative analysis of performance elements (especially axioms and functions), drawing on a number of theatre and mathematical theories. Some suggestions are also put forward in terms of the connection between the performance of mathematised texts and computational mathematics, particularly in terms of an inherent poetics and theatricality inside the performance-oriented, mathematised languages of digital computing