Equation of state SAHA-S meets stellar evolution code CESAM2k

We present an example of an interpolation code of the SAHA-S equation of state that has been adapted for use in the stellar evolution code CESAM2k. The aim is to provide the necessary data and numerical procedures for its implementation in a stellar code. A technical problem is the discrepancy between the sets of thermodynamic quantities provided by the SAHA-S equation of state and those necessary in the CESAM2k computations. Moreover, the independent variables in a practical equation of state (like SAHA-S) are temperature and density, whereas for modelling calculations the variables temperature and pressure are preferable. Specifically for the CESAM2k code, some additional quantities and their derivatives must be provided. To provide the bridge between the equation of state and stellar modelling, we prepare auxiliary tables of the quantities that are demanded in CESAM2k. Then we use cubic spline interpolation to provide both smoothness and a good approximation of the necessary derivatives. Using the B-form of spline representation provides us with an efficient algorithm for three-dimensional interpolation. The table of B-spline coefficients provided can be directly used during stellar model calculations together with the module of cubic spline interpolation. This implementation of the SAHA-S equation of state in the CESAM2k stellar structure and evolution code has been tested on a solar model evolved to the present. A comparison with other equations of state is briefly discussed. The choice of a regular net of mesh points for specific primary quantities in the SAHA-S equation of state, together with accurate and consistently smooth tabulated values, provides an effective algorithm of interpolation in modelling calculations. The proposed module of interpolation procedures can be easily adopted in other evolution codes.Comment: 8 pages, 5 figure

Exact aymptotic expansions for the thermodynamics of hydrogen gas in the Saha regime

We consider the hydrogen quantum plasma in the Saha regime, where it almost reduces to a partially ionized atomic gas. We briefly review the construction of systematic expansions of thermodynamical functions beyond Saha theory, which describes an ideal mixture of ionized protons, ionized electrons and hydrogen atoms in their ground-state. Thanks to the existence of rigorous results, we first identify the simultaneous low-temperature and low-density limit in which Saha theory becomes asymptotically exact. Then, we argue that the screened cluster representation is well suited for calculating corrections, since that formalism accounts for all screening and recombination phenomena at work in a more tractable way than other many-body methods. We sketch the corresponding diagrammatical analysis, which leads to an exact asymptotic expansion for the equation of state. That scaled low-temperature expansion improves the analytical knowledge of the phase diagram. It also provides reliable numerical values over a rather wide range of temperatures and densities, as confirmed by comparisons to quantum Monte Carlo data.Comment: 10 page

Voltage-dependent behavior of a "ball-and-chain" gramicidin channel

This is the published version. Copyright 1997 by Elsevier.The channel-forming properties of two analogs of gramicidin, gramicidin-ethylenediamine (gram-EDA), and gramicidin-N,N-dimethylethylenediamine (gram-DMEDA) were studied in planar lipid bilayers, using protons as the permeant ion. These peptides have positively charged amino groups tethered to their C-terminal ends via a linker containing a carbamate group. Gram-DMEDA has two extra methyl groups attached to the terminal amino group, making it a bulkier derivative. The carbamate groups undergo thermal cis-trans isomerization on the 10–100-ms time scale. The conductance behavior of gram-EDA is found to be markedly voltage dependent, whereas the behavior of gram-DMEDA is not. In addition, voltage affects the cis-trans ratios of the carbamate groups of gram-EDA, but not those of gram-DMEDA. A model is proposed to account for these observations, in which voltage can promote the binding of the terminal amino group of gram-EDA to the pore in a "ball-and-chain" fashion. The bulkiness of the gram-DMEDA derivative prevents this binding

Depression, cognitive dysfunction and other factors associated with 5-year overall mortality in type 2 diabetes mellitus: a pilot prospective observational study

BACKGROUND: Psychological predictors of overall mortality in the Russian population of Type 2 diabetic patients and their impact compared to biological risk factors have not been studied.AIM. To identify clinical, laboratory and psychological factors independently associated with the 5-year overall mortality in Type 2 diabetic patients in the Moscow region.MATERIALS AND METHODS: This open label observational prospective study included 178 consecutive type 2 diabetic patients (women 145, men 33, age range 37 to 82 years, duration of diabetes 0,5 to 30 years). At baseline, in addition to the standard clinical, laboratory and instrumental work-up, all patients were assessed for depression, cognitive dysfunction and diabetes-related quality of life. No study-related intervention was performed; all patients were followed up and treated by their local physicians. After 5 years, we assessed the patients’ vital status (alive or dead). Multiple logistic regression was used to identify baseline patients’ characteristics, which were significantly and independently associated with 5-year overall mortality. Taking into account the exploratory type of multiple regression, the results were considered significant at α<0.1.RESULTS: At 5 years, 150 (84%) patients were alive and 15 (8,4%) were dead; no information could be obtained for the rest 13 (7,3%) patients. The analysis of 165 patients with the verified outcome, independent and significant associations with the death outcome were found for male gender (odds ratio [OR] 6,36 [95%CI 0,91–44.40]; p=0.06), age (OR 2.06 [1.30–3.27]; p<0.002), chronic heart failure (CHF) (OR 2.78 [1.25–6.2]; р=0.012), Hamilton depression scale score (OR 1,18 [1.03–1.34]; р=0.016), cognitive dysfunction score (Roschina scale) (OR 1.20 [1.05–1.35]; р=0.006), and age — body mass index interaction (OR 0,98 [0,97–0,997]; р = 0,013). The predicted probability of death within the next 5 years in men and women was 22,9% and 6,7%, respectively. The highest score of cognitive dysfunction was associated with a 25% predicted probability of death and the lowest, with a 2% probability of death; predicted probabilities of death for the highest and lowest depression scores were 26% and 2%, respectively. The 5-year predicted probability of death in the patients without CHF was 6,7%, with CHF I NYHA functional class, 9,8%, II functional class 13,6%, III functional class 18,2%, and IV functional class 23,5%. All other baseline clinical, laboratory, demographic, psychological and socioeconomic variables were not significantly associated with the 5-year survival rate. The model was not verified on an external cohort.CONCLUSION: Cognitive dysfunction and depression have a significant negative impact on the 5-year mortality rate at much higher degree, than glycemic control, any diabetes-related complications and cardiovascular disorders, excluding CHF. The results obtained highlight the importance of the diagnosis and treatment of depression and cognitive dysfunction in type 2 diabetes mellitus

Search for sterile neutrinos at the DANSS experiment

DANSS is a highly segmented 1~m${}^3$ plastic scintillator detector. Its 2500 one meter long scintillator strips have a Gd-loaded reflective cover. The DANSS detector is placed under an industrial 3.1~$\mathrm{GW_{th}}$ reactor of the Kalinin Nuclear Power Plant 350~km NW from Moscow. The distance to the core is varied on-line from 10.7~m to 12.7~m. The reactor building provides about 50~m water-equivalent shielding against the cosmic background. DANSS detects almost 5000 $\widetilde\nu_e$ per day at the closest position with the cosmic background less than 3$\%$. The inverse beta decay process is used to detect $\widetilde\nu_e$. Sterile neutrinos are searched for assuming the $4\nu$ model (3 active and 1 sterile $\nu$). The exclusion area in the $\Delta m_{14}^2,\sin^22\theta_{14}$ plane is obtained using a ratio of positron energy spectra collected at different distances. Therefore results do not depend on the shape and normalization of the reactor $\widetilde\nu_e$ spectrum, as well as on the detector efficiency. Results are based on 966 thousand antineutrino events collected at 3 distances from the reactor core. The excluded area covers a wide range of the sterile neutrino parameters up to $\sin^22\theta_{14}<0.01$ in the most sensitive region.Comment: 10 pages, 13 figures, version accepted for publicatio

Модели традиционной химической кинетики и потенциально-потоковые уравнения для закрытой системы

The paper analyzes the communication matrix coefficients reagiruemostey simple subsystems and the coefficient matrix formed independent subsystems simple reagents chemically reacting systems with chemical kinetics. He showed that the coefficient matrix and the matrix of coefficients reagiruemostey formed independent reagents simple subsystems have the following Items supplied: symmetry; reagiruemostey coefficient matrix in the second subsystem is the sum of simple and symmetric nonnegative definite matrices, at least one of which is positive definite, due to different mechanisms of chemical reactions. Also property of these matrices simple subsystems as matrices susceptibility is positive definiteness of these matrices. The symmetry of these positive- definite matrices follows from the principle of independence stages kinetic mechanism of chemical transformations. Under such constraints matrix corresponds to the general features of the kinetic mechanism of chemical transformations. The paper shows that when comparing potentially streaming method of modeling chemical reactions in a closed system of chemically reacting with traditional chemical kinetics of these two methods are equivalent. Proposed potentially streaming method is preferred in the absence of the detailed mechanism of complex chemically reacting systems. If the total kinetic information is not available, it is preferable to use the proposed potentially streaming method agreed with the non-equilibrium thermodynamics.В работе проводится сопоставление потенциально-потокового метода моделирования химических превращений в закрытой химически реагирующей системе с методами традиционной химической кинетики. Накладываются ограничения симметричности на матрицу восприимчивостей, связанные с принципом независимости элементарных стадий

DANSSino: a pilot version of the DANSS neutrino detector

DANSSino is a reduced pilot version of a solid-state detector of reactor antineutrinos (to be created within the DANSS project and installed under the industrial 3 GW(th) reactor of the Kalinin Nuclear Power Plant -- KNPP). Numerous tests performed at a distance of 11 m from the reactor core demonstrate operability of the chosen design and reveal the main sources of the background. In spite of its small size (20x20x100 ccm), the pilot detector turned out to be quite sensitive to reactor antineutrinos, detecting about 70 IBD events per day with the signal-to-background ratio about unity.Comment: 16 pages, 11 figures, 3 tables. arXiv admin note: substantial text overlap with arXiv:1304.369