1,721,346 research outputs found
Search for CP violation in the charmless decay using triple product asymmetries at LHCb and feasibility studies of a SiPM-based readout system for the Upgrade II RICH detector
No full textThe subject of CP symmetry and its violation is often referred to as one of the least understood in particle physics. Indeed, CP symmetry violation is an expected consequence of the Standard Model with three quark generations, but calculations within this framework show that the predicted amount of violation is too small to generate the matter-anti-matter imbalance observed in our universe. So far, direct CP violation has been established in K, B and D meson decays and the experimental measurements are in good agreement with the Standard Model expectations. However, CP violation is yet to be confirmed in heavy baryon decays and also in B decays with half-spin particles in the final state, where sizeable asymmetries are predicted as well. In particular, baryonic B-meson decays mediated dominantly through internal W emission are believed to be promising processes. In the first part of this thesis a search for CP violation in the charmless baryonic meson decay using data collected by the LHCb experiment is reported. Multi-body decays of this kind are a good place to search for CP violation because, due to their rich resonant structures, different amplitudes may interfere and cause local CP violation effects to appear in regions of the phase space. This analysis makes use of triple product correlations, a model- independent method with complementary sensitivity with respect to the direct CP asymmetry. The analysis uses data corresponding to an integrated luminosity of 9 fb^−1 collected during Run 1 and Run 2 from 2011 to 2018 and represents the first measurement of this kind in this channel. In order to assign the correct mass to the charged hadrons in the final state and combine them to form the candidate, the particle identification information (PID) provided by the RICH detector are necessary. The two LHCb RICH (Ring Imaging Cherenkov) detectors exploit the Cherenkov light emitted by charged particles traversing a gas to distinguish efficiently π, K and p in the momentum range 1-100 GeV/c. During Run 1 and Run 2 the two RICH detectors operated continuously at the luminosity of ∼ 4×10^32 cm−2s−1 and provided an excellent PID. In order to be able to operate at the new luminosity of ∼ 2 × 10^33 cm−2s−1 from the start of Run 3 (start of the Upgrade I phase) in 2021 the two RICH detectors must be upgraded; the former HPD (Hybrid Photon Detectors) will be replaced by commercial MaPMTs, the optics of the upstream RICH will be modified and the electronics will be upgraded to cope with the challenges of the 40 MHz readout rate. In the second part of this thesis, the development of the detector control system (DCS) for the Upgrade I RICH detector is presented. The DCS partition is the control domain responsible for all the slow control equipment, i.e. control and monitoring of the low voltage (LV), temperature, humidity, pressure etc. The last part of this thesis concerns the feasibility studies for the Upgrade II LHCb RICH detector. The start of the HL-LHC phase in 2027 provides an opportunity to increase the luminosity up to ∼ 10^34 cm−2s−1. To be able to operate the RICH detectors in this much harsher environment a further upgrade in the front-end electronics and a new photo-detector system will be mandatory. I investigated the possibility of using SiPMs (Silicon Photomultipliers) as photo-detectors in the Upgrade II phase by characterizing a device manifactured by Hamamatsu at low temperatures (down to -40 degree celsius) in the lab. The work done in this thesis is still preliminary, but the results obtained in the lab represent valuable inputs towards the design of a new detector prototype
A direct echocardiographic sign of pulmonary embolism after percutaneous embolectomy in a female patient
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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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