1,720,981 research outputs found
Low-temperature behavior of the quark-meson model
No full textWe revisit the phase diagram of strong-interaction matter for the two-flavor quark-meson model using the functional renormalization group. In contrast to standard mean-field calculations, an unusual phase structure is encountered at low temperatures and large quark chemical potentials. In particular, we identify a regime where the pressure decreases with increasing temperature and discuss possible reasons for this unphysical behavior
Fluktuationen in kalter und dichter QCD-Materie mit funktionalen Methoden
Full text linkThis work is aimed at the study of fluctuation effects in cold and dense strong-interaction matter. In Nature, such matter exists in the cores of neutron stars and its properties are largely unknown. Utilizing an effective quark-meson truncation to quantum chromodynamics with two and three quark flavors, we integrate out quantum fluctuations by means of the functional renormalization group (FRG) method and study their impact on the properties of compact stars.
The required thermodynamic equation of state (EoS) is hereby calculated for beta-equilibrated and neutral quark matter. We find significant differences to conventional EoS obtained from simple mean-field approximations. Pure quark-matter stars based on the nonperturbative EoS have larger radii and masses than their mean-field counterparts. Furthermore, the EoS obtained with the FRG allows for the construction of hybrid stars, i.e., neutron stars with a quark-matter core, as long as the utilized nucleonic equation of state is not too stiff. The underlying Maxwell construction assumes a sharp interface between nucleonic and quark matter and leads to a single continuous branch in the mass-radius diagram. However, with the inclusion of strangeness the popular two-solar-mass limit for the experimentally observed maximum mass cannot be reached anymore.
With the additional inclusion of repulsive vector-meson interactions on a mean-field level, we find a sufficient increase in the EoS's stiffness to permit hybrid stars with masses over 2. However, a Maxwell construction with nucleonic equations of state that lead to smaller overall radii and tidal deformabilities in better agreement with experiment is still not possible.
Moreover, we investigate the origin of the strange back-bending of the chiral phase transition line at low temperatures in the quark-meson model in local potential approximation. We observe that the back-bending depends on the regulator function used by the FRG. For Callan-Symanzik-type regulators, it vanishes along with the associated negative entropy densities. This hints at the existence of strong cutoff-scheme-dependent truncation artifacts in local potential approximation at finite density and low temperatures.Sonstige Drittmittelgeber/-inne
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
Higher-order ratios of baryon number cumulants
No full textSchaefer B-J, Wagner M. Higher-order ratios of baryon number cumulants. Central European Journal of Physics. 2012;10(6):1326-1329.The relevance of higher order cumulants of net baryon number fluctuations forthe analysis of freeze-out and critical conditions in heavy-ion collisions atLHC and RHIC is addressed. The sign structure of the higher order cumulants inthe vicinity of the chiral crossover temperature might be a sensitive probe andmay allow to elucidate their relation to the QCD phase transition. We calculateratios of generalized quark-number susceptibilities to high orders in threeflavor QCD-like models and investigate their sign structure close to the chiralcrossover line
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
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