Shear viscosity of degenerate electron matter

We calculate the partial electron shear viscosity $\eta_{ee}$ limited by electron-electron collisions in a strongly degenerate electron gas taking into account the Landau damping of transverse plasmons. The Landau damping strongly suppresses $\eta_{ee}$ in the domain of ultrarelativistic degenerate electrons and modifies its %asymptotic temperature behavior. The efficiency of the electron shear viscosity in the cores of white dwarfs and envelopes of neutron stars is analyzed.Comment: 16 pages, 4 figures, accepted to Journal of Physics

SU(2) Skyrme Vortices

A regular method for constructing vortex-like solutions with cylindrical symmetry to the equations of the SU(2) Skyrme chiral model is proposed. A numerical estimate for the length density of mass is given

Impact of neutron star oscillations on the accelerating electric field in the polar cap of pulsar: or could we see oscillations of the neutron star after the glitch in pulsar?

Pulsar "standard model", that considers a pulsar as a rotating magnetized conducting sphere surrounded by plasma, is generalized to the case of oscillating star. We developed an algorithm for calculation of the Goldreich-Julian charge density for this case. We consider distortion of the accelerating zone in the polar cap of pulsar by neutron star oscillations. It is shown that for oscillation modes with high harmonic numbers (l,m) changes in the Goldreich-Julian charge density caused by pulsations of neutron star could lead to significant altering of an accelerating electric field in the polar cap of pulsar. In the moderately optimistic scenario, that assumes excitation of the neutron star oscillations by glitches, it could be possible to detect altering of the pulsar radioemission due to modulation of the accelerating field.Comment: 7 pages, 8 figures. Presented at the conference "Isolated Neutron Stars: from the Interior to the Surface", London, April 24-28, 2006; to appear in Astrophysics and Space Scienc

Aseguramiento de protección contra el fuego en complejos industriales de agrupaciones animales

This study deals with ensuring fire safety in buildings of a cluster animal industrial complex by optimizing legislative measures and analyzing factors that affect the quality and reliability of the results of calculating fire risk. The research involved the following methods: expert assessment; calculating individual fire risk; modeling evacuation of people in the form of an individual flow model of human traffic. The conceptual features of the complex's buildings required developing the design and technical solutions that would reduce inefficient costs on the one hand, and, on the other, would ensure meeting fire safety requirements. The individual fire risk for employees of the asset to be protected is 2.91 ×10-7 per year-1 (0.291 ×10-6 per year). That is, it does not exceed the characteristic value established by Federal law No. 123-FZ dated 22.07.2008 'Technical regulations on fire safety'. After the introduction of the fire risk assessment system at the legislative level, the owners of objects have received the opportunity to optimize the cost of fire safety and the required level of human safety.Aquí se presenta el estudio del aseguramiento de la protección contra el fuego en edificios agrupados de un conjunto de ganadería por medio de optimizar las medidas legislativas respectivas y analizar las influencias en la calidad y fiabilidad de los resultados de evaluar riesgos de incendio. Se llevaron a cabo los estudios a través de hacer valoración profesional, calcular riesgos de incendio individuales y simular la evacuación de la gente en el modelo de flujos humanos individual y en cadena. Los aspectos funcionales conceptuales de los edificios del conjunto resultaron en la necesidad de desarrollar soluciones técnicas y estructurales que podrían ayudar a reducir gastos ineficientes y armonizarían los edificios con las exigencias de la protección contra el fuego. El riesgo de incendios indivudual para los trabajadores del objeto de protección considerado es 2.91x10-7 por año-1 (0.291x10-6 por año), es decir, no sobrepasa el nivel normal establecido por la ley Federal 123-FZ del 22 de Julio de 2008 «Regulaciones Técnicas de las Exigencias a la Protección contra el Fuego». La adopción en el nivel legislativo del sistema de valorar riesgos de incendio creó para los dueños de objetos la oportunidad de optimizar los gastos para asegurar la protección contra el fuego, incluyendo el aseguramiento del nivel exigido de seguridad humana

Aseguramiento de protección contra el fuego en complejos industriales de agrupaciones animales

Aquí se presenta el estudio del aseguramiento de la protección contra el fuego en edificios agrupados de un conjunto de ganadería por medio de optimizar las medidas legislativas respectivas y analizar las influencias en la calidad y fiabilidad de los resultados de evaluar riesgos de incendio. Se llevaron a cabo los estudios a través de hacer valoración profesional, calcular riesgos de incendio individuales y simular la evacuación de la gente en el modelo de flujos humanos individual y en cadena. Los aspectos funcionales conceptuales de los edificios del conjunto resultaron en la necesidad de desarrollar soluciones técnicas y estructurales que podrían ayudar a reducir gastos ineficientes y armonizarían los edificios con las exigencias de la protección contra el fuego. El riesgo de incendios individual para los trabajadores del objeto de protección considerado es 2.91x10-7 por año-1 (0.291x10-6 por año), es decir, no sobrepasa el nivel normal establecido por la ley Federal 123-FZ del 22 de Julio de 2008 «Regulaciones Técnicas de las Exigencias a la Protección contra el Fuego". La adopción en el nivel legislativo del sistema de valorar riesgos de incendio creó para los dueños de objetos la oportunidad de optimizar los gastos para asegurar la protección contra el fuego, incluyendo el aseguramiento del nivel exigido de seguridad human

Large collection of astrophysical S-factors and its compact representation

Numerous nuclear reactions in the crust of accreting neutron stars are strongly affected by dense plasma environment. Simulations of superbursts, deep crustal heating and other nuclear burning phenomena in neutron stars require astrophysical S-factors for these reactions (as a function of center-of-mass energy E of colliding nuclei). A large database of S-factors is created for about 5000 non-resonant fusion reactions involving stable and unstable isotopes of Be, B, C, N, O, F, Ne, Na, Mg, and Si. It extends the previous database of about 1000 reactions involving isotopes of C, O, Ne, and Mg. The calculations are performed using the Sao Paulo potential and the barrier penetration formalism. All calculated S-data are parameterized by an analytic model for S(E) proposed before [Phys. Rev. C 82, 044609 (2010)] and further elaborated here. For a given reaction, the present S(E)-model contains three parameters. These parameters are easily interpolated along reactions involving isotopes of the same elements with only seven input parameters, giving an ultracompact, accurate, simple, and uniform database. The S(E) approximation can also be used to estimate theoretical uncertainties of S(E) and nuclear reaction rates in dense matter, as illustrated for the case of the 34Ne+34Ne reaction in the inner crust of an accreting neutron star.Comment: 13 pages, 2 figures, Phys. Rev. C, accepte

Contact melting by a non-isothermal heating surface of arbitrary shape

Contact melting a material by a moving heater of arbitrary shapes with non-isothermal working surface is systematically investigated. A pressure exerted by the heater continuously squeezes the molten layer out of the close-contact region. The melting material has non-linear physical properties including temperature dependent conductivity, viscosity and non-Newtonian behaviors. By using a scale analysis momentum and energy equations are simplified. An iterative numerical procedure based on a boundary elements method is developed. Computed results show a good agreement with the analytical solutions that are available for a parabolic isothermal heating surface and constant physical properties. Influences of temperature distributions along the working surface and lengths of the heater on the thickness of the molten layer are found. A comparison between these factors is made. An appropriate distribution of the heat source within the heater is also proposed. © 1995

Formation scenarios and mass-radius relation for neutron stars

Neutron star crust, formed via accretion of matter from a companion in a low-mass X-ray binary (LMXB), has an equation of state (EOS) stiffer than that of catalyzed matter. At a given neutron star mass, M, the radius of a star with an accreted crust is therefore larger, by DR(M), than for usually considered star built of catalyzed matter. Using a compressible liquid drop model of nuclei, we calculate, within the one-component plasma approximation, the EOSs corresponding to different nuclear compositions of ashes of X-ray bursts in LMXB. These EOSs are then applied for studying the effect of different formation scenarios on the neutron-star mass-radius relation. Assuming the SLy EOS for neutron star's liquid core, derived by Douchin & Haensel (2001), we find that at M=1.4 M_sun the star with accreted crust has a radius more than 100 m larger that for the crust of catalyzed matter. Using smallness of the crust mass compared to M, we derive a formula that relates DR(M) to the difference in the crust EOS. This very precise formula gives also analytic dependence of DR on M and R of the reference star built of catalyzed matter. The formula is valid for any EOS of the liquid core. Rotation of neutron star makes DR(M) larger. We derive an approximate but very precise formula that gives difference in equatorial radii, DR_eq(M), as a function of stellar rotation frequency.Comment: 6 pages, 4 figures. Accepted for publication in Astronomy and Astrophysic