1,721,209 research outputs found
Two-loop QCD corrections to the V → qq ̄ g helicity amplitudes with axial-vector couplings
Full text linkWe compute the two-loop corrections to the helicity amplitudes for the coupling of a massive vector boson to a massless quark-antiquark pair and a gluon, accounting for vector and axial-vector couplings of the vector boson and distinguishing isospin non-singlet and singlet contributions. A new four-dimensional basis for the decomposition of the amplitudes into 12 invariant tensor structures is introduced. The associated form factors are then computed up to two loops in QCD using dimensional regularization. After performing renormalization and infrared subtraction, the finite parts of the renormalized non-singlet vector and axial-vector form factors are shown agree with each other, and to reproduce the previously known two-loop amplitudes. The singlet axial-vector amplitude receives a contribution from the axial anomaly from two loops onwards. This amplitude is computed for massless and massive internal quarks. Our results provide the last missing two-loop amplitudes entering the NNLO QCD corrections of vector-boson-plus-jet production at hadron colliders
Master integrals for massless three-loop form-factors: One-loop and two-loop insertions
No full textGehrmann T, Heinrich G, Huber T, Studerus C. Master integrals for massless three-loop form-factors: One-loop and two-loop insertions. Phys.Lett.B. 2006;640(5-6):252-259.The three-loop form factors in massless QCD can be expressed as a linear combination of master integrals. Besides a number of master integrals which factorise into products of one-loop and two-loop integrals, one finds 16 genuine three-loop integrals. Of these, six have the form of a bubble insertion inside a one-loop or two-loop vertex integral. We compute all master integrals with these insertion topologies
Two-Loop Corrections to Top-Antitop Production at Hadron Colliders
Full text linkBonciani R, Ferroglia A, Gehrmann T, von Manteuffel A, Studerus C. Two-Loop Corrections to Top-Antitop Production at Hadron Colliders. In: PoS. Vol ICHEP2010. 2010: 098
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
Bioinformatic Analysis of Genomic and Transcriptomic Variation in Fungi
No full textFungi are microorganisms whose astounding variety can be found in every conceivable ecosystem on the planet. Fungi are nutrient recyclers, playing an irreplaceable role in the carbon cycle. They grow on land and in the sea, on plants and animals and in the soil. They feed us as mushrooms, and drive our economy as bioreactors. They leaven our bread and brew our beer, nourish our crops and spoil our food. They even directly play a role in human health. Fungi are, however, far more complex organisms than their simple phenotypes lead us to believe. In order to harness the potential of fungi, and to address the threats they pose, we must gain a better understanding of fungi. However, their substantial genomic and regulatory diversity impede our reasoning. Thus, to understand fungi, we need to understand their genetic and regulatory diversity.In this thesis, I developed and utilized bioinformatics methods to understandvariation within and between fungi. We focussed on two fungi: Agaricus bisporus (the champignon, or white button mushroom) because of commercial interest, and Schizophyllum commune (the split-gill mushroom) because it is used as a model organism for mushroom formation (for, amongst others, A. bisporus).Pattern Recognition and Bioinformatic
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
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