1,721,215 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
Study of collisional losses in the large hadron collider for Pb-Pb and p-Pb operation
Full text linkLAUREA MAGISTRALEOgni anno di funzionamento, per circa un mese, il Large Hadron Collider (LHC) del CERN è utilizzato per collidere ioni pesanti. Ioni Pb-208 completamente ionizzati sono accelerati fino a 7 Z TeV e fatti collider tra loro (Pb-Pb) o con protoni (p-Pb). Finora sono state eseguite quattro run Pb-Pb e due run p-Pb. Il programma a ioni pesanti dell'LHC proseguirà in futuro, con maggiori luminosità ed energia del fascio. Le perdite del fascio dovute alla frammentazione degli ioni nelle collisioni possono introdurre limitazioni nelle performance. In particolare, durante le collisioni Pb-Pb, la bound-free-pair-production (BFPP) causa una deposizione di potenza localizzata a valle di ciascun punto di interazione (IP) tale da indurre il dump del fascio o il quench dei magneti superconduttori, imponendo quindi un limite alla luminosità. Questo lavoro si propone di studiare le perdite da BFPP nell'esperimento LHCb, e di creare un modello di simulazione affidabile che possa essere utilizzato per prevedere le perdite collisionali in operazioni future. Per la prima volta è stata condotta un'analisi delle perdite da BFPP in LHCb, utilizzando il codice di simulazione SixTrack. È stata proposta una strategia di mitigazione parziale con orbit bumps, che non richiedono l'installazione di nuovo hardware nell'LHC. Essa consentirebbe di aumentare, senza rischi per la macchina, la luminosità livellata di LHCb di un fattore 2-3 nelle run future. Un nuovo approccio di simulazione, in grado di simulare le perdite che si verificano intorno all'anello dell'LHC durante le collisioni Pb-Pb e p-Pb, è stato presentato e validato. Questo consiste nell'accoppiare i codici SixTrack e FLUKA per simulare le collisioni tra i fasci negli IP e tracciare le traiettorie dei prodotti delle collisioni. Lossmaps collisionali sono state simulate e confrontate con quelle misurate per entrambe le run Pb-Pb del 2018 e p-Pb del 2016. L'approccio di simulazione proposto si è dimostrato in grado di fornire risultati con un eccellente accordo con i dati sperimentali e può essere considerato un valido strumento per predire le perdite del fascio in scenari futuri. Infine, le lossmaps collisionali per le future run Pb-Pb e p-Pb sono state stimate, includendo nel setup di simulazione tutte le modifiche previste per la futura configurazione dell'LHC.During about one month per operational year, the Large Hadron Collider (LHC) at CERN works as a heavy-ion collider. Fully-stripped Pb-208 ions are accelerated up to 7 Z TeV and brought into collision between themselves (Pb-Pb) or with protons (p-Pb). Four one-month Pb-Pb runs have been executed so far as well as two p-Pb runs. The LHC heavy-ion programme is scheduled to continue in the future, featuring increased luminosity and beam energy. Beam losses caused by ions fragmenting in the collision process risk introducing performance limitations. Most notably, when colliding Pb-Pb nuclei, the bound-free pair production (BFPP) causes a localized power deposition downstream of each interaction point (IP), which can induce beam dumps or the quench of superconducting magnets, hence imposing an upper limit on the luminosity. This work aims both at studying alleviations of BFPP losses at the LHCb experiment, as well as setting up a reliable simulation model that can be used to predict collisional losses in future operation. For the first time a full analysis of the BFPP losses at LHCb has been conducted, adopting the simulation code SixTrack. A partial mitigation strategy by means of orbit bumps, which do not require any new hardware to be installed in the LHC, has been proposed. It would allow to safely increase the levelled luminosity of LHCb by a factor 2-3 in future runs. A new simulation approach to simulate the losses arising around the LHC ring during Pb-Pb and p-Pb collisions has been presented and benchmarked. It relies on the SixTrack-FLUKA coupling to simulate the beam-beam collisions at the IPs and track the collision products. Collisional lossmaps have been simulated and compared to the measured data for both 2018 Pb-Pb and 2016 p-Pb runs. The simulation approach proposed has proven capable of providing results with an excellent agreement with experimental data and it can be considered a valid tool to estimate the beam losses for future operation. Consequently, the prediction of Pb-Pb and p-Pb master lossmaps for future runs has been provided, including in the simulation setup all the changes envisaged for the next machine configuration
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
Studies of crystal collimation for heavy ion operation at the LHC
No full textAt CERN's Large Hadron Collider (LHC), proton and heavy-ion beams are accelerated to multi-TeV energies to be collided for the needs of the scientific community around the world. The total stored beam energy of tens to hundreds ofMJ creates potential threats to the hardware around the collider in case of uncontrolled beam loss. Energy deposited by lost particles may damage impacted elements or cause the LHC magnets to lose their superconducting state, creating unnecessary downtime and decreasing physics production efficiency. To protect the machine a multi-stage collimation system was installed, designed primarily for proton operation but to be used also for heavy ions. However, with the upgrades for High-Luminosity LHC (HL-LHC), the total stored beam energy is to increase from 13MJ to around 20MJ. This demands an upgrade also from the collimation side to safely intercept higher beam losses that are to be expected due to higher intensity. Because of the fragmentation of heavy ions inside
the collimators, which causes a significant leakage out of the collimators of particles with a charge-to-mass ratio that is different from the main beam, the collimation for heavy ions is more challenging than for protons. Hence, based on the studies performed in the past, it was decided to introduce a new collimation method with a potential for increased performance, called crystal collimation, in the operational baseline, already in 2023, when also the beams from the injectors with higher intensity became available.
The imminence of ion operations with crystal collimation presses for amore thorough understanding of this novel method applied on heavy ions. For this reason, this thesis describes a complete simulation framework that has been built for ion crystal collimation. This tool allows a better understanding of the characteristics of crystal collimation for ions, probe for collimation optimizations, and performpredictive analysis for future collimation configurations. The simulation framework is based on the existing SixTrack-FLUKA coupling. This thesis presents the construction of the simulation framework, the benchmark with old and new data, detailed simulation studies of the LHC collimation performance in various configurations, including the one of the first heavy-ion physics run with crystal collimation in 2023, and other alternative setups.LPA
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
Study of beam-gas interaction at the LHC for the Physics Beyond Collider Fixed-Target study
Full text linkAmong several working groups formed in the framework of Physics Beyond Colliders study, launched at CERN in September 2016, there is one investigating some specific fixed-target experiment proposals. Of particular interest is the study of high-density unpolarized or polarized gas target to be installed upstream the LHCb detector using storage cells located around the beam to enhance the target density. This work studies the impact of the interactions of 7 TeV proton beams with such gas targets on the LHC machine in terms of particle losses. The overall compatibility with the planned high-intensity program of the LHC is also discussed. A calculation is also performed of the minimum acceptable radius for such a storage cell in order to ensure safe operational conditions.ope
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
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