1,720,962 research outputs found
New physics searches in angular shapes of photon+jet events in 2013 ATLAS data
No full textThe Large Hadron Collider at CERN, Switzerland, was built to both refine current Standard Model measurements, as well as discover new physics beyond the Standard Model. Using data from the general-purpose ATLAS detector, we take a step towards answering one of these questions: are quarks point-like, or do they themselves have sub-structure? By investigating the angular correlations in photon+jet events we address this question. The final goal of this thesis was to produce a feasible method to test deviations from the Standard Model using 2012 ATLAS data. A new data-driven background estimation analysis technique was developed to test for significant deviations from Standard Model predictions. We parametrize the angular separation between the leading photon and jet in each event with the variable (where is pseudorapidity) using standard ATLAS Monte Carlo generators Pythia, Sherpa, and JetPhox. Kinematic comparisons are performed between 2012 ATLAS data and Monte Carlo samples to show how well data is described by the generators. We take the ratio of the number of narrowly-separated () to selected events with as a function of invariant mass of the final state photon and the final state jet, resulting in our observable distribution . We fit the numerator and denominator invariant mass distributions separately and obtain the background estimate of the distribution in each bin by dividing the results of the fit in each bin. We use a bootstrap method for statistical error estimation. Our analysis techniques were optimized with the Excited Quark model as a benchmark model. Using the developed methodology for background estimation, we proceed to estimate the expected signal sensitivity of this analysis technique to excited quark production in the full 2012 ATLAS dataset of 20.3 fb.Le Grand collisionneur de hadrons au CERN, en Suisse, a été construit afin d'améliorer les mesures actuelles du Modèle Standard et pour tenter de découvrir des phénomènes physiques qui ne sont pas décrits par le Modèle Standard. En utilisant les données amassées par le détecteur ATLAS, nous nous penchons sur un de ces phénomènes: les quarks sont-ils des particules ponctuelles ou ont-ils plutôt une structure interne? Nous nous servons des corrélations angulaires entre les photons et les gerbes de particules dans l'état final de collisions à hautes énergies pour étudier la question. Le but de ce mémoire est de démontrer l'efficacité de cette technique d'analyse et d'en étudier la performance avec les données prises par ATLAS en 2012. Nous présentons une nouvelle technique d'estimation du bruit de fond causé par les processus physiques du Modèle Standard et un test qui permet de déterminer si les données d'ATLAS dévient significativement par rapport à ce bruit de fond. Nous paramétrons la séparation angulaire entre le photon le plus énergétique et la gerbe la plus énergétique dans chaque événement par (où est la pseudorapidité) en utilisant des données simulées par les générateurs Monte Carlo Pythia, Sherpa et JetPhox. Nous comparons les distributions des variables cinétiques entre les données ATLAS et les événement simulés pour démontrer que les données simulées reproduisent bien les caractéristiques des données réelles. Nous définissons un nouvel observable qui représente la fraction des événements qui ont une petite séparation angulaire ( est plus petit que 1.5) parmi les événements acceptés ( est plus petit que 5) en fonction de la masse au repos du système photon+gerbe. Un ajustement de courbe est fait séparément pour les distributions de masse au repos qui constituent le numérateur et le dénominateur de l'observable . La prédiction du bruit de fond en dans chaque intervalle de masse au repos est obtenue par le résultat de la division des valeurs des deux courbes ajustées dans cet intervalle. L'incertitude statistique est calculée à l'aide d'une méthode de type "bootstrap". La méthode analytique est optimisée en utilisant comme modèle de référence le modèle du quark excité. Avec notre nouvelle méthode d'estimation du bruit de fond, notre technique d'analyse et notre signal de référence, nous mesurons la valeur attendee pour la détection d'un signal de quark excité dans les 20.3 fb^-1 de données ATLAS de 2012
Modeling routing problems in QUBO with application to ride-hailing
Get PDFMany emerging commercial services are based on the sharing or pooling of
resources for common use with the aim of reducing costs. Businesses such as
delivery-, mobility-, or transport-as-a-service have become standard in many
parts of the world, fulfilling on-demand requests for customers in live
settings. However, it is known that many of these problems are NP-hard, and
therefore both modeling and solving them accurately is a challenge. Here we
focus on one such routing problem, the Ride Pooling Problem (RPP), where
multiple customers can request on-demand pickups and drop-offs from shared
vehicles within a fleet. The combinatorial optimization task is to optimally
pool customer requests using the limited set of vehicles, akin to a small-scale
flexible bus route. In this work, we propose a quadratic unconstrained binary
optimization (QUBO) program and introduce efficient formulation methods for the
RPP to be solved using metaheuristics, and specifically emerging quantum
optimization algorithms
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
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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