323,545 research outputs found
Mesonische Korrelationsfunktionen aus leichten Quarks und ihre spektrale Darstellung in heißer gequenchter Gitter-QCD
No full textWissel S. Mesonic correlation functions from light quarks and their spectral representation in hot quenched lattice QCD. Bielefeld (Germany): Bielefeld University; 2006.In dieser Arbeit untersuchen wir anhand von Gittersimulationen der Quantenchromodynamik thermische in-medium Modifikationen für unterschiedliche Mesonkorrelationsfunktionen bei leichten Valenzquarkmassen und verschwindenden chemischen Potentials. Mesonische Eigenschaften werden in der Regel anhand räumlicher Korrelationsfunktionen extrahiert. Die Ergebnisse basieren dabei auf gequenchten Eichfeldkonfigurationen, die mit Hilfe der standard Wilson Plaquette Eichwirkung erzeugt werden. Bezüglich des fermionischen Anteils der Wirkung verwenden wir die nicht-störungstheoretische O(a) verbesserte Sheikholeshami-Wohlert sowie eine auf den Hyperkubus trunkierte perfekte Wirkung. Ferner wird die maximale Entropie Methode verwendet, um anhand von Spektralfunktionen physikalisch relevante Polmassen zu bestimmen und thermische Modifikationen physikalischer Zustände sowie möglicher Gitterartefakte im wechselwirkenden Fall zu untersuchen.
Die Auswertung von Pol- und Screeningmassen, Dispersionsrelationen, Wellenfunktionen, Zerfallskonstanten und Spektralfunktionen hat im wesentlichen ergeben, dass wir bis 0,55 Tc keine signifikanten Veränderungen zum null Temperatur Verhalten erkennen können. Erst nahe dem Phasenübergang scheinen sich in-medium Effekte bemerkbar zu machen, was u.a. zu einer signifikanten Abweichung zwischen Pol- und Screeningmassen geführt hat. Die Zerfallskonstanten sind in guter Übereinstimmung mit den experimentellen Werten. Oberhalb von Tc haben wir mit einer quasi null Quarkmasse simuliert. Bei 1,24 Tc hat das Auftreten topologischer Effekte als ein Zeichen für eine immer noch vorhandene U(1)_A Symmetriebrechung eine eingehendere Analyse in direkter Nähe des Phasenübergangs verhindert.
Eine vollständige Kontinuums- und Volumen-Extrapolation der Screening Massen, orientiert an dem Verhalten freier Gitter effektiven Massen, wird durchgeführt. Diese zeigt, dass noch vorhandene kollektive Phänomene bei 1,5 und 3 Tc nicht durch einfache Gittereffekte erklärt werden können. Anders als das Vektormeson ist das pseudoskalare Meson weit davon entfernt, ein ungebundener Zustand zu sein.In this thesis we investigate thermal in-medium modifications of various mesonic correlation functions by lattice simulations of Quantum Chromodynamics for light valence quark masses and vanishing chemical potential. Mesonic properties are typically extracted from spatial correlation functions. The results presented are based on quenched gauge field configurations generated with the standard Wilson plaquette gauge action. Concerning the fermionic part of the action, we use the non-perturbative O(a) improved Sheikholeslami-Wohlert as well as the truncated hypercube perfect action. Furthermore we utilize the maximum entropy method in order to determine physically relevant pole masses and to investigate thermal modifications of physical states and possible lattice artefacts in the interacting case.
The analyses of pole and screening masses, dispersion relations, wave functions, decay constants and spectral functions essentially yield no significant modifications of the zero-temperature behavior up to 0.55 Tc. Close to the phase transition in-medium effects seem to appear, which lead inter alia to significant differences between pole and screening masses. The decay constants are in good agreement with the experimental values. We have simulated above Tc at nearly zero quark masses. At 1.24 Tc, the occurrence of topological effects, a sign for the presence of a still broken U(1)_A symmetry, prevent a more thorough analyses close to the phase transition.
A complete continuum and infinite volume extrapolation of screening masses, guided by free lattice effective masses is done. It shows that the presence of collective phenomena at 1.5 and 3 Tc cannot be explained by pure lattice artefacts. Unlike the vector meson the pion is far from being considered an unbound state
Charmonia at finite momenta in a deconfined plasma
No full textDatta S, Karsch F, Wissel S, Petreczky P, Wetzorke I. Charmonia at finite momenta in a deconfined plasma. 2004
Hadronic excitations at high temperature
No full textLaermann E, Karsch F, Shcheredin S, Wissel S. Hadronic excitations at high temperature. In: Nuclear Physics A. NUCLEAR PHYSICS A. Vol 785. ELSEVIER SCIENCE BV; 2007: 261C-265C
Meson correlation functions at high temperatures
No full textWissel S, Laermann E, Shcheredin S, Datta S, Karsch F. Meson correlation functions at high temperatures. PoS. 2006;LAT2005:164
Diffusive author(s), cohesive author: Analysis of S/N (1994)
No full textThis study indicates the ways in which various aspects of the author(s) are brought forth in Dumb type’s performance art, the S/N production. Previous research has suggested a non-hierarchical organization of Dumb type and the absence of a “privileged author” in Dumb type’s collaborative work, S/N. However, the results that I have investigated from member’s interviews on the creative process of S/N along with my analysis of the recorded images of S/N, indicate a different aspect of the author(s). First, S/N was created through, so to speak, the collective ideas of the members of Dumb type. Further, S/N has at least nine quotations from previous performances, installations, and printed writings, besides the work-in-progress technique. Explicating one of the “author functions” as given by Michel Foucault, each text has plural subjects of the author. However, it has been revealed from members’ interviews that Teiji Furuhashi had a decision-making role in selecting the members’ ideas within the performance. Since then, S/N has had plural subjects of creation; however, Furuhashi is one of the subjects of creation along with the “privileged author.” S/N has plural authors (diffusive authors) yet at the same time, it has a “privileged author,” Teiji Furuhashi (cohesive author)
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe 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
Dispelling the Myths Behind First-author Citation Counts
No full textWe 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
Author's address:
No full textCan archives of audiovisual TV interviews be used to make authors more visible to students, and thereby reduce the learning gap between native and non-native language speakers in college classes? We examined students in a college course who learned about one scholar's ideas through watching an audiovisual TV interview (i.e., visible author format) and about another scholar's ideas through reading a formal text description (i.e., invisible author format). For the invisible author, native language speakers scored significantly higher than the non-native language speakers on a corresponding exam question (i.e., a cognitive measure), generated more words on the exam question (i.e., a motivational measure), and mentioned the author's name more often in answering the exam question (i.e., an affective measure). For the visible author, the groups did not differ on any of these measures. These findings provide evidence for the idea that making the author visible through audiovisual TV interviews can eliminate the learning gap between native and non-native language speakers. 3 Universities around the world serve students who are non-native speakers of th
The vanishing author in computer-generated works: a critical analysis of recent Australian case law
No full textAbstract
The use of software is ubiquitous in the creation of many copyright works, yet the requirement in copyright law that every work have a human author who engages in independent intellectual effort means that its use may prevent copyright subsistence. Several recent Australian cases have refocused attention on authorship as an essential criterion of copyright subsistence, and these cases suggest that much computer-produced output may be authorless and thus lack copyright protection. This article, the first in a two-part series, analyses how each case deals with the question of authorship of computer-produced works and why the use of software diminishes copyright protection for a significant number of computer-generated works. The article critiques the application of conventional notions of human authorship developed in the pre-computer age to modern productions and suggests alternative approaches to authorship that satisfy both the major objectives of copyright policy and the need to adapt to the computer age. The article argues that, without a broader judicial approach to authorship of computer-generated works, Parliament must remedy the lacuna in protection for these ‘authorless’ works. Possible solutions for reform are suggested. In a forthcoming article, the author comprehensively examines those reform proposals
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