On projective group properties of the 6D6D pseudo-Riemannian space

We study the six-dimensional pseudo-Riemannian spaces with two time-like coordinates that admit non-homothetic infinitesimal projective transformations. The metrics are manifestly obtained and the projective group properties are determined. We also find a generic defining of projective motion in the 6-dimensional rigid h-space.Comment: 4 pages, talk presented at the "Integrable Systems-2005", Prague, 200

The volume of causal diamonds, asymptotically de Sitter space-times and irreversibility

In this note we prove that the volume of a causal diamond associated with an inertial observer in asymptotically de Sitter 4-dimensional space-time is monotonically increasing function of cosmological time. The asymptotic value of the volume is that of in maximally symmetric de Sitter space-time. The monotonic property of the volume is checked in two cases: in vacuum and in the presence of a massless scalar field. In vacuum, the volume flow (with respect to cosmological time) asymptotically vanishes if and only if future space-like infinity is 3-manifold of constant curvature. The volume flow thus represents irreversibility of asymptotic evolution in spacetimes with positive cosmological constant.Comment: 15 pages, no figures; v.2: conjecture 1 on p. 11 made more precise; version published in jhe

D-branes, String Cosmology and Large Extra Dimensions

D-branes are fundamental in all scenarios where there are large extra dimensions and the string scale is much smaller than the four-dimensional Planck mass. We show that this current picture leads to a new approach to string cosmology where inflation on our brane is driven by the large extra dimensions and the issue of the graceful exit becomes inextricably linked to the problem of the stabilization of the extra dimensions, suggesting the possibility of a common solution. We also show that branes may violently fluctuate along their transverse directions in curved spacetime, possibly leading to a period of brane-driven inflation. This phenomenon plays also a crucial role in many other cosmological issues, such as the smoothing out of the cosmological singularities and the generation of the baryon asymmetry on our three brane.Comment: LaTeX file, 4 page

Quantum gravity corrections to the Schwarzschild mass

Vacuum spherically symmetric Einstein gravity in $N\ge 4$ dimensions can be cast in a two-dimensional conformal nonlinear sigma model form by first integrating on the $(N-2)$-dimensional (hyper)sphere and then performing a canonical transformation. The conformal sigma model is described by two fields which are related to the Arnowitt-Deser-Misner mass and to the radius of the $(N-2)$-dimensional (hyper)sphere, respectively. By quantizing perturbatively the theory we estimate the quantum corrections to the ADM mass of a black hole.Comment: 18 pages, 8 figures, LaTeX2e, uses epsfig package, accepted for publication in Phys. Rev.

A minimal set of invariants as a systematic approach to higher order gravity models: Physical and Cosmological Constraints

We compare higher order gravity models to observational constraints from magnitude-redshift supernova data, distance to the last scattering surface of the CMB, and Baryon Acoustic Oscillations. We follow a recently proposed systematic approach to higher order gravity models based on minimal sets of curvature invariants, and select models that pass some physical acceptability conditions (free of ghost instabilities, real and positive propagation speeds, and free of separatrices). Models that satisfy these physical and observational constraints are found in this analysis and do provide fits to the data that are very close to those of the LCDM concordance model. However, we find that the limitation of the models considered here comes from the presence of superluminal mode propagations for the constrained parameter space of the models.Comment: 12 pages, 6 figure

About Bianchi I with VSL

In this paper we study how to attack, through different techniques, a perfect fluid Bianchi I model with variable G,c and Lambda, but taking into account the effects of a $c$-variable into the curvature tensor. We study the model under the assumption,div(T)=0. These tactics are: Lie groups method (LM), imposing a particular symmetry, self-similarity (SS), matter collineations (MC) and kinematical self-similarity (KSS). We compare both tactics since they are quite similar (symmetry principles). We arrive to the conclusion that the LM is too restrictive and brings us to get only the flat FRW solution. The SS, MC and KSS approaches bring us to obtain all the quantities depending on \int c(t)dt. Therefore, in order to study their behavior we impose some physical restrictions like for example the condition q<0 (accelerating universe). In this way we find that $c$ is a growing time function and Lambda is a decreasing time function whose sing depends on the equation of state, w, while the exponents of the scale factor must satisfy the conditions $\sum_{i=1}^{3}\alpha_{i}=1$ and $\sum_{i=1}^{3}\alpha_{i}^{2}<1,$ $\forall\omega$, i.e. for all equation of state$,$ relaxing in this way the Kasner conditions. The behavior of $G$ depends on two parameters, the equation of state $\omega$ and $\epsilon,$ a parameter that controls the behavior of $c(t),$ therefore $G$ may be growing or decreasing.We also show that through the Lie method, there is no difference between to study the field equations under the assumption of a $c-$var affecting to the curvature tensor which the other one where it is not considered such effects.Nevertheless, it is essential to consider such effects in the cases studied under the SS, MC, and KSS hypotheses.Comment: 29 pages, Revtex4, Accepted for publication in Astrophysics & Space Scienc

Phase Behavior of Aqueous Na-K-Mg-Ca-CI-NO3 Mixtures: Isopiestic Measurements and Thermodynamic Modeling

A comprehensive model has been established for calculating thermodynamic properties of multicomponent aqueous systems containing the Na{sup +}, K{sup +}, Mg{sup 2+}, Ca{sup 2+}, Cl{sup -}, and NO{sub 3}{sup -} ions. The thermodynamic framework is based on a previously developed model for mixed-solvent electrolyte solutions. The framework has been designed to reproduce the properties of salt solutions at temperatures ranging from the freezing point to 300 C and concentrations ranging from infinite dilution to the fused salt limit. The model has been parameterized using a combination of an extensive literature database and new isopiestic measurements for thirteen salt mixtures at 140 C. The measurements have been performed using Oak Ridge National Laboratory's (ORNL) previously designed gravimetric isopiestic apparatus, which makes it possible to detect solid phase precipitation. Water activities are reported for mixtures with a fixed ratio of salts as a function of the total apparent salt mole fraction. The isopiestic measurements reported here simultaneously reflect two fundamental properties of the system, i.e., the activity of water as a function of solution concentration and the occurrence of solid-liquid transitions. The thermodynamic model accurately reproduces the new isopiestic data as well as literature data for binary, ternary and higher-order subsystems. Because of its high accuracy in calculating vapor-liquid and solid-liquid equilibria, the model is suitable for studying deliquescence behavior of multicomponent salt systems

Measurement of the top-quark mass using a leptonic invariant mass in pp collisions at s√ = 13 TeV with the ATLAS detector

A measurement of the top-quark mass (mt) in the tt¯ → lepton + jets channel is presented, with an experimental technique which exploits semileptonic decays of b-hadrons produced in the top-quark decay chain. The distribution of the invariant mass mℓμ of the lepton, ℓ (with ℓ = e, μ), from the W-boson decay and the muon, μ, originating from the b-hadron decay is reconstructed, and a binned-template profile likelihood fit is performed to extract mt. The measurement is based on data corresponding to an integrated luminosity of 36.1 fb−1 of s√ = 13 TeV pp collisions provided by the Large Hadron Collider and recorded by the ATLAS detector. The measured value of the top-quark mass is mt = 174.41 ± 0.39 (stat.) ± 0.66 (syst.) ± 0.25 (recoil) GeV, where the third uncertainty arises from changing the PYTHIA8 parton shower gluon-recoil scheme, used in top-quark decays, to a recently developed setup

Changes in the structure of pathogens of calculous pyelonephritis complicated with diabetes mellitus type ii, in the hospital urology of the city of Volgograd

Among the diseases complicating the course of calculous pyelonephritis, are among the leaders of diabetes mellitus, which is associated with reduced immune response, deterioration of renal hemodynamics, the reduced sensitivity to antibacterial drugs. The purpose of the study is to improve the results of treatment of patients with calculous pyelonephritis and diabetes mellitus type 2. The materials and methods of research. We studied 179 people. This was a retrospective pharmaco-epidemiological analysis of medical records of patients who were treated in 2009 and 2013, in hospital of Volgograd. Women in the study was greater than 99(by 55.4%), males - 80 (44,6%). All patients underwent standard clinical examination, with mandatory bacteriological urine analysis, ultrasound study of kidneys.RESULTS: During the observation period of 2009 and 2013 in patients with calculous pyelonephritis and type 2 diabetes, the major pathogens were representatives of the family Enterobacteriaceae. E.coli strains are constituted - 12 (54,5%), K. pneumoniae - 4 (18.1%) strains. In other etiologically significant microorganisms were Enterococcus spp. - 3 (13.6%) strain, P. aeruginosa - strain 2 (9%). The group of other (4.5%), we have carried pathogens isolated in the singular: Erobacter spp, S. aureus, and Klebsiella oxytoca. In patients with infection of the upper urinary tract and diabetes, there is a pronounced trend to decrease sensitivity to all groups of antibiotics. Sensitivity to unprotected penicillins and fluoroquinolones has decreased almost twice. Resistance to aminoglycosides of patients in this group increased by 23%. In patients with chronic calculous pyelonephritis and diabetes mellitus type 2 is high sensitivity of the main causative agents of infection to cephalosporins of the third and fourth generation (92%), protected beta-lactam penicillins (amoxicillin/clavulanate) - 86,4%, to carbapenemam is 89.4%.CONCLUSIONS: For the empiric treatment of infections of the upper urinary tract in patients with diabetes mellitus, can be recommended drugs: protected beta-lactam penicillins, cephalosporins of the third and fourth generation, carbapenem

Changes in the structure of pathogens of calculous pyelonephritis complicated with diabetes mellitus type ii, in the hospital urology of the city of Volgograd

Among the diseases complicating the course of calculous pyelonephritis, are among the leaders of diabetes mellitus, which is associated with reduced immune response, deterioration of renal hemodynamics, the reduced sensitivity to antibacterial drugs. The purpose of the study is to improve the results of treatment of patients with calculous pyelonephritis and diabetes mellitus type 2. The materials and methods of research. We studied 179 people. This was a retrospective pharmaco-epidemiological analysis of medical records of patients who were treated in 2009 and 2013, in hospital of Volgograd. Women in the study was greater than 99(by 55.4%), males - 80 (44,6%). All patients underwent standard clinical examination, with mandatory bacteriological urine analysis, ultrasound study of kidneys.RESULTS: During the observation period of 2009 and 2013 in patients with calculous pyelonephritis and type 2 diabetes, the major pathogens were representatives of the family Enterobacteriaceae. E.coli strains are constituted - 12 (54,5%), K. pneumoniae - 4 (18.1%) strains. In other etiologically significant microorganisms were Enterococcus spp. - 3 (13.6%) strain, P. aeruginosa - strain 2 (9%). The group of other (4.5%), we have carried pathogens isolated in the singular: Erobacter spp, S. aureus, and Klebsiella oxytoca. In patients with infection of the upper urinary tract and diabetes, there is a pronounced trend to decrease sensitivity to all groups of antibiotics. Sensitivity to unprotected penicillins and fluoroquinolones has decreased almost twice. Resistance to aminoglycosides of patients in this group increased by 23%. In patients with chronic calculous pyelonephritis and diabetes mellitus type 2 is high sensitivity of the main causative agents of infection to cephalosporins of the third and fourth generation (92%), protected beta-lactam penicillins (amoxicillin/clavulanate) - 86,4%, to carbapenemam is 89.4%.CONCLUSIONS: For the empiric treatment of infections of the upper urinary tract in patients with diabetes mellitus, can be recommended drugs: protected beta-lactam penicillins, cephalosporins of the third and fourth generation, carbapenem