1,721,120 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
Design and characterization of pixel IC electronics and sensors for new pixel detector generations
Full text linkThe LHC High Luminosity upgrade will result in a significant change of environment in which the particle detectors are going to operate, especially for devices very close to the interaction point like the pixel detectors and their electronics. In order to meet the needs of future detectors R&D programs on all their design aspects are being carried out. This work covers two such topics. The first topic is the development of Depleted Monolithic Active Pixel Senor (DMAPS), which combine the sensor and electronics into one entity. The prototypes are shown to have a performance adequate for HL-LHC ATLAS outer pixel layers and therefore present an interesting, low cost alternative to the baseline hybrid pixel designs. The second topic is the design and characterization of a Clock Data Recovery (CDR) circuit for the pixel readout chip developed for the ATLAS and CMS HL-LHC upgrades. The circuit is shown to have good jitter performance and is radiation hard both in terms of both the Total Ionizing Dose and the Single Event Effects
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
Measurement of Lepton Mass Squared Moments of B→X<sub>c</sub>lν<sub>l</sub> Decays with the Belle II Experiment and Determination of the CKM Matrix Element |V<sub>cb</sub>|
No full textThis thesis presents measurements of the first to fourth moments of the lepton mass squared q2=(pl + pν)2 distribution of B→Xclν decays for l=e,μ and with Xc denoting a hadronic system containing a charm quark.
These results use a sample of e+e--collisions at the Υ(4S) resonance corresponding to 62.8 fb-1 of integrated luminosity and collected by the Belle II experiment in 2019 and 2020.
To identify the Xc system and reconstruct q2, one of the B mesons from an Υ(4S)→BB decay is fully reconstructed in a hadronic decay mode using a multivariate B tagging algorithm.
The yields of the remaining e+e-→qqcontinuum and BB background events are determined with a binned likelihood fit to the hadronic mass mX distribution.
To correct the bias in the mean value of the reconstructed q2 distribution, an event-wised calibration method is applied to the reconstructed q2 values.
The q2 moments are calculated as a weighted mean using the calibrated q2 values summing all selected events.
In this approach, the weights denote a signal probability and effectively subtract the contribution of the remaining background events.
This work reports raw and central q2 moments measured as functions of lower q2 thresholds from q2 > 1.5 GeV2 up to q2 > 8.5 GeV2, probing up to 77% of the accessible B→Xclν phase space.
This is the first measurement of moments in the experimentally challenging range of q2 ∈ [1.5, 2.5] GeV.
In addition, this thesis presents a first determination of |Vcb| using q2 moments of inclusive B→Xclν decays.
Like the prediction of total rate, the expressions for spectral moments of inclusive semileptonic PB decays can be calculated using the heavy quark expansion and depend on a set of non-perturbative parameters which can only be determined from measurements.
At higher orders in the expansion, one observes a proliferation of these parameters which further complicates their extraction.
The q2 moments and the total rate are reparameterization invariant quantities and depend on a reduced set of non-perturbative parameters.
This reduced set of parameters opens a new path to extract these parameters up to O(1/mb4) in the HQE purely from data and thereby reducing the uncertainty on |Vcb|.
A combined fit to the q2 moments measured in this work and by the Belle collaboration is used to extract |Vcb|.
The fit results in |Vcb| = (41.69±0.63)·10-3.
This result presents an important independent cross-check of, and is consistent with, the previous state-of-the-art inclusive |Vcb| determinations based on lepton energy and hadronic mass moments
First observation of the semileptonic decay B - -> D s + K - l - ny l with the BABAR detector
No full textMeasurements of <em>q</em><sup>2</sup> moments of inclusive <em>B</em> → <em>X<sub>c</sub></em>ℓν decays toward an alternative determination of |<em>V<sub>cb</sub></em>|
No full textThis thesis presents the first measurement of the first to the fourth moments of the four-momentum transfer squared q2 spectrum for inclusive B → Xcℓν decays, where ℓ = e, μ. The determination of these moments and their systematic uncertainties are crucial experimental inputs for a novel, alternative method to determine the magnitude of the CKM matrix element Vcb using a reduced set of hadronic matrix elements in the heavy quark expansion. The analysis investigates the complete ϒ(4S) data set collected by the Belle detector, corresponding to 711 fb-1 of integrated luminosity and a total of (772 ± 10) × 106 B meson pairs. To identify and reconstruct the kinematic variables of inclusive semileptonic B meson decays, machine learning techniques are employed to fully reconstruct one of the B mesons in purely hadronic decay modes. Consequently, this approach allows for the kinematics of the remaining B meson to be inferred using conservation laws leading to the explicit reconstruction of the hadronic Xc system and, in turn, the q2 spectrum. The moments are measured with progressively increasing threshold selections on q2: from q2 > 3.0 GeV2 to q2 > 10.0 GeV2 while incrementing the threshold in 0.5 GeV2 steps. To ensure an unbiased result, the measured moments are unfolded and corrected for reconstruction and selection effects. The measured moments are reported separately for electron and muon final states, allowing for a test of lepton flavour universality. No deviation from the expectation of unity is observed. In addition, the presented measurement is combined with theoretical predictions of the ⟨qn⟩ moments and the semileptonic decay rate up to order 1/mb4 to perform a simultaneous fit and extract |Vcb| in a data-driven manner. A value of |Vcb| × 103 = 41.7 ± 1.2 is obtained, which is consistent with previous determinations within experimental uncertainty
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