1,721,735 research outputs found
Misura di elettroni da decadimenti di adroni pesanti e produzione di barioni pesanti con l'esperimento ALICE a LHC
Full text linkThe ALICE experiment at the LHC at CERN is devoted to the study of collisions of heavy nuclei accelerated at ultra-relativistic energies. These collisions are employed to reproduce in laboratory the quark-gluon plasma (QGP), a deconfined state of the strongly-interacting matter. %characterised by the quark and gluon degrees of freedom.
The existence of this state is predicted by the QCD theory under extreme conditions of energy-density and temperature. The QGP is supposed to constitute the early universe in the first \mjs after the Big Bang. Charm and beauty quarks are unique probes for investigating the QGP. Given a mass of the GeV order, they are produced in the hard-scattering processes in the early stages of the nucleus-nucleus collision, experiencing the full evolution of the system. Charm and beauty quarks lose energy by interacting with the plasma constituents. These phenomena can be studied by measuring the heavy-flavour hadron production and exploited to infer properties of the system. In this thesis, the production of electrons from charm and beauty hadron decays in central (0--10\%), semicentral (30--50\%) and peripheral (60--80\%) Pb--Pb collisions at \sNNsqrt=5.02 TeV measured with the ALICE experiment is presented. These results are compared with those in pp collisions by means of the nuclear modification factor () and a significant suppression with respect to what expected in absence of a deconfined medium is observed in central and semicentral events. This behaviour indicates that charm and beauty quarks are subject to in-medium energy loss. The observed effect decreases in more peripheral events. The measurement is pushed down to MeV/, where the heavy quark production is sensitive to the shadowing effects. The does not overcome unity, signalling that the production of heavy-flavour hadrons is suppressed. The QGP formation in heavy-ion collisions is expected to induce a modification of the heavy quark hadronisation mechanisms. In order to disentangle the effects of the medium produced in Pb--Pb collisions, a deep comprehension of the mechanisms that govern the hadronisation in pp collisions is required. Recent results on baryon-to-meson production ratios in pp collisions at the LHC showed an enhancement with respect to and collisions. %, indicating that the hadronisation via fragmentation is not enough.
In this thesis, the measurement of the and baryon production cross section in pp collisions at TeV with the ALICE experiment is described. The ratio to the meson production of both baryons is significantly higher than what measured in and collisions. The measurements are described by several model calculations assuming different mechanisms for the charm quark hadronisation. Moreover, the first measurement of the prompt feed-down from decays in pp collisions is presented and observed to be times larger than collisions in the interval GeV/. The investigation of the charm quark hadronisation mechanisms in hadronic collisions can significantly benefit from production measurements of more charm baryons. In the last Chapter, a few studies on the capabilities to perform such measurements in the future with the ALICE experiment are discussed. New frontiers in the heavy-flavour hadron production measurements will be allowed by the significantly higher statistics that the experiment will collect in the upcoming years, as well as the improved pointing resolution provided by the upgraded ITS detector.The ALICE experiment at the LHC at CERN is devoted to the study of collisions of heavy nuclei accelerated at ultra-relativistic energies. These collisions are employed to reproduce in laboratory the quark-gluon plasma (QGP), a deconfined state of the strongly-interacting matter. %characterised by the quark and gluon degrees of freedom.
The existence of this state is predicted by the QCD theory under extreme conditions of energy-density and temperature. The QGP is supposed to constitute the early universe in the first \mjs after the Big Bang. Charm and beauty quarks are unique probes for investigating the QGP. Given a mass of the GeV order, they are produced in the hard-scattering processes in the early stages of the nucleus-nucleus collision, experiencing the full evolution of the system. Charm and beauty quarks lose energy by interacting with the plasma constituents. These phenomena can be studied by measuring the heavy-flavour hadron production and exploited to infer properties of the system. In this thesis, the production of electrons from charm and beauty hadron decays in central (0--10\%), semicentral (30--50\%) and peripheral (60--80\%) Pb--Pb collisions at \sNNsqrt=5.02 TeV measured with the ALICE experiment is presented. These results are compared with those in pp collisions by means of the nuclear modification factor () and a significant suppression with respect to what expected in absence of a deconfined medium is observed in central and semicentral events. This behaviour indicates that charm and beauty quarks are subject to in-medium energy loss. The observed effect decreases in more peripheral events. The measurement is pushed down to MeV/, where the heavy quark production is sensitive to the shadowing effects. The does not overcome unity, signalling that the production of heavy-flavour hadrons is suppressed. The QGP formation in heavy-ion collisions is expected to induce a modification of the heavy quark hadronisation mechanisms. In order to disentangle the effects of the medium produced in Pb--Pb collisions, a deep comprehension of the mechanisms that govern the hadronisation in pp collisions is required. Recent results on baryon-to-meson production ratios in pp collisions at the LHC showed an enhancement with respect to and collisions. %, indicating that the hadronisation via fragmentation is not enough.
In this thesis, the measurement of the and baryon production cross section in pp collisions at TeV with the ALICE experiment is described. The ratio to the meson production of both baryons is significantly higher than what measured in and collisions. The measurements are described by several model calculations assuming different mechanisms for the charm quark hadronisation. Moreover, the first measurement of the prompt feed-down from decays in pp collisions is presented and observed to be times larger than collisions in the interval GeV/. The investigation of the charm quark hadronisation mechanisms in hadronic collisions can significantly benefit from production measurements of more charm baryons. In the last Chapter, a few studies on the capabilities to perform such measurements in the future with the ALICE experiment are discussed. New frontiers in the heavy-flavour hadron production measurements will be allowed by the significantly higher statistics that the experiment will collect in the upcoming years, as well as the improved pointing resolution provided by the upgraded ITS detector
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
Author Under Sail The Imagination of Jack London, 1893-1902
No full textIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Intro -- Title Page -- Copyright Page -- Dedication -- Contents -- Acknowledgments -- Introduction -- 1. Spirit Truth -- 2. From Absorption to Theatricality and Back Again -- 3. "I Will Build a New Present" -- 4. Sons as Authors -- 5. Fathers as Publishers -- 6. The Daughter as Author -- 7. Lovers as Authors -- 8. At Sea with the Family -- 9. Yellow News, Yellow Stories -- 10. The Return Home -- Notes -- Bibliography -- Index -- About Jay WilliamsIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Description based on publisher supplied metadata and other sources.Electronic reproduction. Ann Arbor, Michigan : ProQuest Ebook Central, YYYY. Available via World Wide Web. Access may be limited to ProQuest Ebook Central affiliated libraries
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