130 research outputs found

    The Newman-Janis Algorithm, Rotating Solutions and Einstein-Born-Infeld Black Holes

    Get PDF
    A new metric is obtained by applying a complex coordinate trans- formation to the static metric of the self-gravitating Born-Infeld monopole. The behaviour of the new metric is typical of a rotating charged source, but this source is not a spherically symmetric Born-Infeld monopole with rotation. We show that the structure of the energy-momentum tensor obtained with this new metric does not correspond to the typical structure of the energy momentum tensor of Einstein-Born-Infeld theory induced by a rotating spherically symmetric source. This also show, that the complex coordinate transformations have the interpretation given by Newman and Janis only in space-time solutions with linear sources

    Off-diagonal correlations of the Calogero-Sutherland model

    Full text link
    We study correlation functions of the Calogero-Sutherland model in the whole range of the interaction parameter. Using the replica method we obtain analytical expressions for the long-distance asymptotics of the one-body density matrix in addition to the previously derived asymptotics of the pair-distribution function [D.M. Gangardt and A. Kamenev, Nucl. Phys. B, 610, 578 (2001)]. The leading analytic and non-analytic terms in the short-distance expansion of the one-body density matrix are discussed. Exact numerical results for these correlation functions are obtained using Monte Carlo techniques for all distances. The momentum distribution and static structure factor are calculated. The potential and kinetic energies are obtained using the Hellmann-Feynman theorem. Perfect agreement is found between the analytical expressions and numerical data. These results allow for the description of physical regimes of the Calogero-Sutherland model. The zero temperature phase diagram is found to be of a crossover type and includes quasi-condensation, quasi-crystallization and quasi-supersolid regimes.Comment: 17 pages, 7 figure

    Endoscopic hemostasis in the ulcer gastro-duodenal hemorrhage, using high-frequency biological welding electro-ligature

    Get PDF
    Objective. To improve the efficacy of endoscopic hemostasis for the ulcer gastro-duodenal hemorrhage, using high-frequency biological welding electro-ligature. Materials and methods. In 2017-2020 yrs period the analysis of efficacy of endoscopic hemostasis was done in 160 patients, ageing 40-85 yrs old, for the ulcer gastro-duodenal hemorrhage. The patients were distributed into two groups: the main - 80 patients, in whom high-frequency biological welding electro-ligature was performed, and a control one - 80 patients, in whom monopolar thermal argon-plasm coagulation was conducted. Results. In the main Group a primary hemostasis was achieved in 77 (96.3%) patients. Early recurrence of hemorrhage have occurred in 3 (3.8%) patients. In a control Group a primary hemostasis was achieved in 66 (82.5%) patients. Recurrence of the hemorrhage have occurred in 14 (17.5%) patients. Conclusion. Endoscopic hemostasis for the ulcer gastro-duodenal hemorrhage, using high-frequency biological welding electro-ligature, is achieved due to the impedance action of modulated signal of a high-frequency current as well as the adaptive system of automatic guidance of the welding process and a contact between special endoscopic probe, owing a concave electrode, with bleeding vessel, leading to its complete obliteration. Application of welding electro-ligature for endoscopic hemostasis in the ulcer gastro-duodenal hemorrhage, using high-frequency biological welding electro-ligature, guarantees more secure residual hemostasis, than application of monopolar thermal argon-plasm coagulation, peculiarly in hemorrhage from vessels owing 2 - 4 mm diameter. As a result, the hemorrhage recurrence rate have had reduced down to 3.8% (in the control Group - 18.0%)

    Microbial diversity and biogeochemical cycling in soda lakes

    Get PDF
    Soda lakes contain high concentrations of sodium carbonates resulting in a stable elevated pH, which provide a unique habitat to a rich diversity of haloalkaliphilic bacteria and archaea. Both cultivation-dependent and -independent methods have aided the identification of key processes and genes in the microbially mediated carbon, nitrogen, and sulfur biogeochemical cycles in soda lakes. In order to survive in this extreme environment, haloalkaliphiles have developed various bioenergetic and structural adaptations to maintain pH homeostasis and intracellular osmotic pressure. The cultivation of a handful of strains has led to the isolation of a number of extremozymes, which allow the cell to perform enzymatic reactions at these extreme conditions. These enzymes potentially contribute to biotechnological applications. In addition, microbial species active in the sulfur cycle can be used for sulfur remediation purposes. Future research should combine both innovative culture methods and state-of-the-art ‘meta-omic’ techniques to gain a comprehensive understanding of the microbes that flourish in these extreme environments and the processes they mediate. Coupling the biogeochemical C, N, and S cycles and identifying where each process takes place on a spatial and temporal scale could unravel the interspecies relationships and thereby reveal more about the ecosystem dynamics of these enigmatic extreme environments

    Measurement of D+- and D0 production in deep inelastic scattering using a lifetime tag at HERA

    Get PDF
    The production of D-+/-- and D-0-mesons has been measured with the ZEUS detector at HERA using an integrated luminosity of 133.6 pb(-1). The measurements cover the kinematic range 5 < Q(2) < 1000 GeV2, 0.02 < y < 0.7, 1.5 < p(T)(D) < 15 GeV and |eta(D)| < 1.6. Combinatorial background to the D-meson signals is reduced by using the ZEUS microvertex detector to reconstruct displaced secondary vertices. Production cross sections are compared with the predictions of next-to-leading-order QCD, which is found to describe the data well. Measurements are extrapolated to the full kinematic phase space in order to obtain the open-charm contribution, F-2(c (c) over bar), to the proton structure function, F-2

    Genomics of alkaliphiles

    Get PDF
    Alkalinicity presents a challenge for life due to a “reversed” proton gradient that is unfavourable to many bioenergetic processes across the membranes of microorganisms. Despite this, many bacteria, archaea, and eukaryotes, collectively termed alkaliphiles, are adapted to life in alkaline ecosystems and are of great scientific and biotechnological interest due to their niche specialization and ability to produce highly stable enzymes. Advances in next-generation sequencing technologies have propelled not only the genomic characterization of many alkaliphilic microorganisms that have been isolated from nature alkaline sources but also our understanding of the functional relationships between different taxa in microbial communities living in these ecosystems. In this review, we discuss the genetics and molecular biology of alkaliphiles from an “omics” point of view, focusing on how metagenomics and transcriptomics have contributed to our understanding of these extremophiles.https://link.springer.com/bookseries/10hj2021BiochemistryGeneticsMicrobiology and Plant Patholog

    Sinus arrhythmia effects on QT dispersion parameters in healthy individuals and coronary heart disease patients

    Get PDF
    Aim. To study sinus arrhythmia (SA) effects on quantitative parameters of time myocardial repolarization dispersion (dQTt) in healthy people and coronary heart disease (CHD) patients, as well to assess the potential of this predictor in CHD diagnostics. Material and methods. In total, 94 healthy people aged 19–60 years, and 54 CHD patients aged 39–57 years, were examined. All participants underwent morning registration of rest electrocardiogram (ECG) in SII for 5 minutes, to measure heart rate variability (HRV), QT duration and dispersion. Results. The difference between mean QTtc dispersions in diapasons of sinus isometry, moderate and manifested SA was observed, irrespective of age. A new diagnostic parameter, dQTtc/RRVR, was proposed for normalizing dQTtc according to SA severity and HR. The predictive value of this parameter was substantially greater than that of HRV characteristics, QT and QTc duration and dispersion. Conclusion. SA and HR-normalized dQTt could be regarded as a diagnostic CHD index, independent of HRV characteristics. Sensitivity and specificity of normalized dQTt in CHD diagnostics is increasing when combined with other parameters
    • 

    corecore