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 ${\mathcal N}=4$ 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 $0.6$ 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 $\eta/s$.Comment: Various small improvements, including additional references. Version to appear in JHE

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

Red-Teaming Segment Anything Model

Foundation models have emerged as pivotal tools, tackling many complex tasks through pre-training on vast datasets and subsequent fine-tuning for specific applications. The Segment Anything Model is one of the first and most well-known foundation models for computer vision segmentation tasks. This work presents a multi-faceted red-teaming analysis that tests the Segment Anything Model against challenging tasks: (1) We analyze the impact of style transfer on segmentation masks, demonstrating that applying adverse weather conditions and raindrops to dashboard images of city roads significantly distorts generated masks. (2) We focus on assessing whether the model can be used for attacks on privacy, such as recognizing celebrities' faces, and show that the model possesses some undesired knowledge in this task. (3) Finally, we check how robust the model is to adversarial attacks on segmentation masks under text prompts. We not only show the effectiveness of popular white-box attacks and resistance to black-box attacks but also introduce a novel approach - Focused Iterative Gradient Attack (FIGA) that combines white-box approaches to construct an efficient attack resulting in a smaller number of modified pixels. All of our testing methods and analyses indicate a need for enhanced safety measures in foundation models for image segmentation.Comment: CVPR 2024 - The 4th Workshop of Adversarial Machine Learning on Computer Vision: Robustness of Foundation Model

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

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