1,720,993 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
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
Search for the Vector Boson Scattering in WW -> 2l2 final state with the CMS detector
No full textMy PhD research activity has been carried out within the CMS collaboration and is focused on data analysis. The CMS experiment is one of the main detectors installed at the Large Hadron Collider (LHC) at CERN, in Geneve, and is a multi-purpose apparatus in the context of high energy physics. During my PhD course in Physics and Astrophysics I have been working on the observation of electroweak WW pair production in association with two jets in proton-proton collisions at TeV, and the paper has been published by the PLB journal. This process belongs to the so-called Vector Boson Scattering (VBS) mechanisms: broadly speaking, the set of VBS processes involve scattering diagrams among gauge vector bosons, i.e. VV VV amplitudes with V being either a W, Z or gamma boson. At the LHC, they manifest in association with two hadronic jets, coming from the interacting quarks that take part in the proton-proton collision. My thesis presents the first observation of the electroweak (EW) production of a WW bosons pair. The analysis is based on the full Run 2 data set collected by the CMS experiment and corresponding to an integrated luminosity of 138 fb. Signal candidates must pass either single or double lepton triggers, as both W bosons are required to decay into a light lepton - electron (e) or muon () - along with its corresponding neutrino. Moreover, two VBS-like jets are selected, i.e. tight kinematic cuts on the dijet invariant mass () and pseudorapidity gap () are applied to the two jets with the highest transverse momentum () in the event. To achieve a better sensitivity to the VBS signal process, both different- and same-flavor final states are considered for this analysis, which, combined together, have enough statistical power to make the observation possible. Indeed, the main challenges of this analysis are the background estimation and reduction techniques, which are fundamental ingredients for measuring such a rare process. Unlike other VBS modes, the WW channel is populated by the top-antitop quark (ttbar) pair production background, which represents the main background source for its huge cross section: a Deep Neural Network (DNN) algorithm is used to disentangle this background and the QCD-induced WW production from the VBS signal in emu categories. On the other hand, ee and final states are dominated by Drell-Yan (DY) events, in which jets from secondary interactions, i.e. pileup jets, fake the real source of transverse missing momentum () that one would expect from the emission of neutrinos. A dedicated strategy is developed to measure this background process, and the variable has enough discriminating power in ee and categories. The statistical significance of the EW WW production is 5.6 standard deviations with respect to the background-only hypothesis (5.2 expected). Two fiducial cross section measurements are quoted for this process, one being more inclusive, as it represents the cross section measured in the phase space where the signal sample has been generated, and the other one being closer to the experimental selection outlined at reconstruction-level. The measured (expected) value is fb for the former and fb for the latter, and they are both in agreement with leading order QCD predictions: fb and fb, respectively. Future data taking periods of the LHC will enable further precision studies in the context of VBS measurement, from the Run 3 - which has just started - to the upcoming high luminosity phase, which will allow to collect more than 3000 fb of new data. In this landscape, differential cross section measurements and combinations of multiple diboson VBS channels will play a key role in understanding the physics of these rare EW processes, possibly pointing to new physics phenomena that governate laws of nature in the realm of high energy interactions
YSF Observation of VBS production in opposite-sign WW events at CMS
No full textThe first observation of Vector Boson Scattering (VBS) in the WW channel is presented. The analyzed data sample corresponds to an integrated luminosity of 138 \ensuremath{\mathrm{fb^{-1}}} of proton-proton collisions at TeV, collected by the CMS detector at the CERN LHC. Fully leptonic final states have been considered, selecting events with exactly two opposite-sign leptons (either electrons or muons) and missing transverse energy due to the escaping neutrinos. Additionally, at least two jets with large pseudorapidity gap (\ensuremath{\Delta\eta_{\mathrm{jj}}}) and high invariant mass (\ensuremath{m_{\mathrm{jj}}}) are required, which are produced in association with the two W bosons. A signal is observed with a significance of 5.6 standard deviations (5.2 expected) with respect to the background-only hypothesis. The measured fiducial cross section is fb and is consistent with the standard model (SM) prediction ( fb)
Recent H WW results using CMS data
No full textRecent results published by the CMS collaboration on analyses of the Higgs boson
decaying into a pair of W bosons are presented, exploting the full data set from
Run 2 of the LHC. The Higgs production in association with a leptonically decaying
vector boson is measured, both inclusively and in the STXS framework. The observed
signal strength modifier is . The Higgs boson
production cross sections are also measured within a fiducial region as a function
of its transverse momentum and the jet multiplicity of the final state. The measurement
is unfolded to the truth-level and compared with different signal models. All
results are compatible with the SM prediction
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
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