1,721,083 research outputs found
Measurement of the tau misidentification probability from QCD jets with ATLAS data at = 7 TeV
No full textIn 2010, the ATLAS experiment recorded 45 pb − 1 of data from proton-proton collisions at a centre- of-mass energy of 7TeV at the LHC. In many signatures of the Standard Model and in searches for new physics the τ -lepton plays an important role. It is identified in the detector by the decay products of its hadronic decay channel. However, the signature in the detector is similar to the signature of QCD jets, which are therefore the main background in studies with τ -leptons. In this thesis the probability to reconstruct and identify a QCD jet as a hadronically decaying τ -lepton is studied. A tag-and-probe method is used to determine the misidentification probability directly from data for the current ATLAS τ identification methods: a cut based identification, boosted decision trees and a projective likelihood. The focus lies on the measurement of the misidentification probability as a function of suitable variables and the determination of systematic uncertainties
Tau lepton identification and studies of associated Higgs boson production with the ATLAS detector
No full textIn this thesis two main topics are presented: the identification of hadronic tau decays and a search for Higgs bosons that decay to tau leptons and are produced in association with a Z boson. In 2012, the ATLAS detector at the LHC recorded 20 fb1 of data at a centre-of-mass energy of 8 TeV. Many studies on Standard Model (SM) processes, as well as searches for physics beyond the SM were carried out, which all rely on a good particle identification. This thesis focuses on the identification of hadronically decaying tau leptons. Multivariate techniques are used to reject backgrounds that mimic the tau signature in the detector and are falsely reconstructed as tau leptons. The focus is on the optimisation of the algorithm using boosted decision trees (BDT). The method is prepared for the 2012 data taking period and made robust against run conditions with many simultaneous protonproton interactions per bunch crossing (pile-up). Furthermore, the dependence of the identification method on the tau momentum is studied, and the usage of additional algorithms that explore the pion content of the tau decay. The second part concerns the Higgs boson which was discovered in 2012. Higgs boson production via a top quark-loop (gg fusion) as well as via vector boson fusion (VBF) has been observed, but no evidence for the production in association with a vector boson (VH) has been claimed yet. The thesis presents a study of this production mode, with a leptonically decaying Z boson in the final state, and the Higgs boson decaying to a pair of tau leptons. Both the hadronic decay of the tau lepton as well as the leptonic decays (_e, __) are considered. The background is estimated from simulation, and renormalised in side bands to match the data. The contribution is then transferred to the signal region using the fake factor method. Combining the result from the four final states _had _had, _e_had, ___had and _e__, a limit is set on the cross section of the process Z(! ee; __)H(! _had_had). No deviation from the Standard Model is found. An upper observed (expected) limit of 8:96 (6:18+8:94 4:45) times the SM cross section is set at 95% confidence level for a Higgs boson mass of 125 GeV
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
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
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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