190 research outputs found
Towards a holographic realization of the quarkyonic phase
Large-N_c QCD matter at intermediate baryon density and low temperatures has
been conjectured to be in the so-called quarkyonic phase, i.e., to have a quark
Fermi surface and on top of it a confined spectrum of excitations. It has been
suggested that the presence of the quark Fermi surface leads to a homogeneous
phase with restored chiral symmetry, which is unstable towards creating
condensates breaking both the chiral and translational symmetry. Motivated by
these exotic features, we investigate properties of cold baryonic matter in the
single flavor Sakai-Sugimoto model searching for a holographic realization of
the quarkyonic phase. We use a simplified mean-field description and focus on
the regime of parametrically large baryon densities, of the order of the square
of the 't Hooft coupling, as they turn out to lead to new physical effects
similar to the ones occurring in the quarkyonic phase. One effect, the
appearance of a particular marginally stable mode breaking translational
invariance and linked with the presence of the Chern-Simons term in the flavor
brane Lagrangian, is known to occur in the deconfined phase of the
Sakai-Sugimoto model, but turns out to be absent here. The other, completely
new phenomenon that we, preliminarily, study using strong simplifying
assumptions are density-enhanced interactions of the flavor brane gauge field
with holographically represented baryons. These seem to significantly affect
the spectrum of vector and axial mesons and might lead to approximate chiral
symmetry restoration in the lowest part of the spectrum, where the mesons start
to qualitatively behave like collective excitations of the dense baryonic
medium. We discuss the relevance of these effects for holographic searches of
the quarkyonic phase and conclude with a discussion of various subtleties
involved in constructing a mean-field holographic description of a dense
baryonic medium.Comment: 31 pages, 16 figures; v2: inset plot in Fig. 10 removed, coloring in
Fig. 13 fixed, typos fixed, matches published versio
Statistics of thermalization in Bjorken Flow
The apparent early thermalization of quark-gluon plasma produced at RHIC and
LHC has motivated a number of studies of strongly coupled
supersymmetric Yang-Mills theory using the AdS/CFT correspondence. Here we
present the results of numerical simulations of Bjorken flow aimed at
establishing typical features of the dynamics. This is done by evolving a large
number of far from equilibrium initial states well into the hydrodynamic
regime. The results strongly suggest that early thermalization is generic in
this theory, taking place at proper times around in units of inverse
local temperature. We also find that the scale which determines the rate of
hydrodynamic cooling is linearly correlated with the entropy of initial states
defined by the area of the apparent horizon in the dual geometry. Our results
also suggest that entropy production during the hydrodynamic stage of evolution
is not negligible despite the low value of .Comment: Various small improvements, including additional references. Version
to appear in JHE
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The Accurate Solution of Certain Continuous Problems Using Only Single Precision
A typical approach for finding the approximate solution of a continuous problem is through discretization with meshsize h such that the truncation error goes to zero with h. The discretization problem is solved in floating point arithmetic. Rounding-errors spoil the theoretical convergence and the error may even tend to infinity. In this paper we present algorithms of moderate cost which use only single precision and which compute the approximate solution of the integration and elliptic equation problems with full accuracy. These algorithms are based on the modified Gill-Møller algorithm for summation of very many terms, iterative refinement of a linear system with a special algorithm for the computation of residuals in single precision and on a property of floating point subtraction of nearby numbers
Volunteer Computing Simulation Using Repast And Mason
Volunteer environments usually consist of a large number of computing nodes,with highly dynamic characteristics, therefore reliable models for a planning ofthe whole computing are highly desired. An easy to implement approach to mo-delling and simulation of such environments may employ agent-based universalsimulation frameworks, such as RePast or MASON. In the course of the paperthe above-mentioned simulation frameworks are adapted to support simulationof volunteer computing. After giving implementation details, selected resultsconcerning computing time and speedup are given and are compared with theones obtained from an actual volunteer environment
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Biochar and biochar with N-fertilizer affect soil N2O emission in Haplic Luvisol
The benefits of biochar application are well described in tropical soils, however there is a dearth of information on its effects in agricultural temperate soils. An interesting and little explored interaction may occur in an intensive agriculture setting; biochar addition may modify the effect of commonplace N-fertilization.We conducted a field experiment to study the effects of biochar application at the rate of 0, 10 and 20 t ha−1 (B0, B10 and B20) in combination with 0, 40 and 80 kg N ha−1 of N-fertilizer (N0, N40, N80).We followed nitrous oxide (N2O) emissions, analysed a series of soil physicochemical properties and measured barley yield in a Haplic Luvisol in Central Europe. Seasonal cumulative N2O emissions from B10N0 and B20N0 treatments decreased by 27 and 25% respectively, when compared to B0N0. Cumulative N2O emissions from N40 and N80 combined with B10 and B20 were also lower by 21, 19 and 25, 32%, respectively compared to controls B0N40 and B0N80. Average pH was significantly increased by biochar addition. Increased soil pH and reduces NO−3 content seen in biochar treatments could be the two possible mechanisms responsible for reduced N2O emissions. There was a statistically significant increase of soil water content in B20N0 treatment compared to B0N0 control, possibly as a result of larger surface area and the presence of microspores having altered pore size distribution and water-holding capacity of the soil. Application of biochar at the rate of 10 t ha−1 had a positive effect on spring barley grain yield
Meta-analysis of postoperative myocardial injury as a predictor of mortality after living donor liver transplantation
Background: The purpose of this study was to perform a systematic review and meta-analysis to investigate postoperative myocardial injury, as expressed by the postoperative concentration of high-sensitivity cardiac troponin I (hs-cTnI) as a predictor of mortality among living donor liver transplantation (LDLT) patients. Methods: PubMed, Scopus, Embase and the Cochrane Library were searched through to September 1st 2022. The primary endpoint included in-hospital mortality. Secondary endpoints were 1-year mortality and re-transplantation occurrence. Estimates are expressed as risk ratios (RRs) and 95% confidence intervals (95% CIs). Heterogeneity was assessed with the I2 test. Results: During the search, 2 studies were found that fit the criteria and had a total of 527 patients. Pooled analysis showed that in-hospital mortality in patients with myocardial injury was 9.9%, compared to 5.0% for patients without myocardial injury (RR = 3.01; 95% CI: 0.97–9.36; p = 0.06). Mortality among 1-year follow-up was 5.0% vs. 2.4%, respectively (RR = 1.90; 95% CI: 0.41–8.81; p = 0.41). Conclusions: In recipients with normal preoperative cTnI, myocardial injury LDLT may be associated with adverse clinical outcomes during a hospital stay, but the results were inconsistent at 1-year follow-up. Although routine follow-up of postoperative hs-cTnI, even in patients with normal preoperative levels, might still help predict the clinical outcome of LDLT. In future large and more representative studies are needed to establish the potential role of cTns in perioperative cardiac risk stratification
Перебіг анемії вагітних у хворих на туберкульоз легень
В статье представлены данные течения анемии беременных и нарушения фетоплацентарного
комплекса у 86 женщин, больных туберкулезом легких. Выявлено, что анемия на фоне туберкулезного
процесса приводит к существенным функциональным и морфологическим нарушениям в плаценте. показано
диагностическое значение оценки плацентарной дисфункции для профилактики и лечения анемии у данного
контингента женщин.The article presents the data of course of pregnancy anemia and failures of fetoplacental complex in 86 women
with pulmonary tuberculosis. It is found that anemia under tuberculous process leads to significant functional and
morphological disturbances in placenta. Diagnostic significance of assessment of placental dysfunction for the
prevention and treatment of anemia in this contingent of women is shown
Systematic review and meta-analysis of the co-occurrence of atrial fibrillation and liver transplantation: a lethal combination
INTRODUCTION: This systematic review and meta-analysis is aimed to evaluate the role of new-onset atrial fibrillation (NOAF) in patients after liver transplantation (LT) and determine the effect of NOAF on the incidence of mortality and graft rejection.
MATERIAL AND METHODS: Published studies until the end of April 15, 2023, were systematically searched in PubMed, Google Scholar, Scopus, Embase, Web of Science, and the Cochrane databases. Odds ratios (ORs) with 95% confidence intervals (CI) for mortality and graft rejection were extracted.
RESULTS: Five studies with a total of 4788 unique post-LT patients were included in the meta-analysis. Pooled analysis showed that mortality in patients with and without NOAF varied and amounted to 24.1% vs. 12.5%, respectively (OR = 2.51; 95%CI: 1.92 to 3.27; p < 0.001). Moreover, pooled analysis showed that graft rejection in the NOAF cohort was 26.3%, and was higher vs. patients without NOAF (13.1%; OR = 2.98; 95%CI: 2.14 to 4.15; p < 0.001)
CONCLUSIONS: Post-LT NOAF is associated with increased mortality and a higher risk of graft rejection. It is likely that the development of a standard procedure for early identification of NOAF, as well as to develop recommendations for specific treatment targeted at avoiding the impacts of the illness, could provide a mortality reduction and provide an increased rate of successful LT
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