Fusion of neutron rich oxygen isotopes in the crust of accreting neutron stars

Fusion reactions in the crust of an accreting neutron star are an important source of heat, and the depth at which these reactions occur is important for determining the temperature profile of the star. Fusion reactions depend strongly on the nuclear charge $Z$. Nuclei with $Z\le 6$ can fuse at low densities in a liquid ocean. However, nuclei with Z=8 or 10 may not burn until higher densities where the crust is solid and electron capture has made the nuclei neutron rich. We calculate the $S$ factor for fusion reactions of neutron rich nuclei including $^{24}$O + $^{24}$O and $^{28}$Ne + $^{28}$Ne. We use a simple barrier penetration model. The $S$ factor could be further enhanced by dynamical effects involving the neutron rich skin. This possible enhancement in $S$ should be studied in the laboratory with neutron rich radioactive beams. We model the structure of the crust with molecular dynamics simulations. We find that the crust of accreting neutron stars may contain micro-crystals or regions of phase separation. Nevertheless, the screening factors that we determine for the enhancement of the rate of thermonuclear reactions are insensitive to these features. Finally, we calculate the rate of thermonuclear $^{24}$O + $^{24}$O fusion and find that $^{24}$O should burn at densities near $10^{11}$ g/cm$^3$. The energy released from this and similar reactions may be important for the temperature profile of the star.Comment: 7 pages, 4 figs, minor changes, to be published in Phys. Rev.

Disjoining Potential and Spreading of Thin Liquid Layers in the Diffuse Interface Model Coupled to Hydrodynamics

The hydrodynamic phase field model is applied to the problem of film spreading on a solid surface. The disjoining potential, responsible for modification of the fluid properties near a three-phase contact line, is computed from the solvability conditions of the density field equation with appropriate boundary conditions imposed on the solid support. The equation describing the motion of a spreading film are derived in the lubrication approximation. In the case of quasi-equilibrium spreading, is shown that the correct sharp-interface limit is obtained, and sample solutions are obtained by numerical integration. It is further shown that evaporation or condensation may strongly affect the dynamics near the contact line, and accounting for kinetic retardation of the interphase transport is necessary to build up a consistent theory.Comment: 14 pages, 5 figures, to appear in PR

Kesici-delici alet yaralanmalarında penetran kardiyak travma: Kardiyak bölgenin doğru tanısına ilişkin bir çalışma

BACKGROUND: Stab wounds (SW) to the thorax raises suspicion for cardiac injuries; however, the topographic description is variable. The present study aims to evaluate different topographical descriptions within the thorax and establish their diagnostic value in penetrating cardiac trauma by SW. METHODS: Medical records of all patients admitted to our center with thoracic SW from January 2013 to June 2016 were included in this study. Diagnostic value potential was measured using different areas of the thorax described in the literature. RESULTS: In this study, we analyzed 306 cases. Thirty-eight (12.4%) patients had a cardiac injury managed surgically. Death by cardiac injury occurred in seven (18.4%) patients. The cardiac area defined between the right mid-clavicle line until the left anterior axillary line, and between 2nd and 6th intercostal spaces was the more accurate. It has sensitivity of 97.3%, specificity 72%, positive predictive value 33%, negative predictive value 99.4% and accuracy 75.1% for penetrating cardiac trauma. ROC was 0.894 IC 95% (0.760–0.901). CONCLUSION: Among the thoracic areas, topographical limits between the right mid-clavicle line and the left anterior axillary line, and between 2nd and 6th intercostal spaces are the more accurate and are highly indicative of cardiac injury in patients with SW to the thorax

On the Interface Formation Model for Dynamic Triple Lines

This paper revisits the theory of Y. Shikhmurzaev on forming interfaces as a continuum thermodynamical model for dynamic triple lines. We start with the derivation of the balances for mass, momentum, energy and entropy in a three-phase fluid system with full interfacial physics, including a brief review of the relevant transport theorems on interfaces and triple lines. Employing the entropy principle in the form given in [Bothe & Dreyer, Acta Mechanica, doi:10.1007/s00707-014-1275-1] but extended to this more general case, we arrive at the entropy production and perform a linear closure, except for a nonlinear closure for the sorption processes. Specialized to the isothermal case, we obtain a thermodynamically consistent mathematical model for dynamic triple lines and show that the total available energy is a strict Lyapunov function for this system

Seroprevalencia de Brucella abortus en bovinos del departamento de Huila - Colombia

El objetivo de este trabajo fue determinar la seroprevalencia de brucelosis bovina en el departamento de Huila, mediante la detección de anticuerpos contra Brucella abortus. El estudio se desarrolló en el periodo comprendido entre mayo de 2011 a diciembre de 2012 en el que se realizaron análisis serológicos de 14.741 bovinos de los cuales 14.010 fueron hembras y 731 machoslocalizados en 333 predios de 28 municipios de esta zona del país; dicha información se recopiló de los resultados obtenidos por el ICA conjuntamente con el organismo de inspección. Se utilizó comoprueba tamiz, la técnica deaglutinación con rosa de bengala y se realizo pruebas confirmatoriasde fluorescencia polarizaday ELISA competitiva.Los resultado obtenidos por zona muestran que la mayor prevalencia se localiza en el norte con 2,69%, seguido por la zona occidental 1,90%, el centro 1,23% y la zona sur 0,18%. En general en el departamento de Huila las cifras de prevalencia de brucelosis bovina son bajas 1,90% en animales y moderadas 28,80%para predios. Lo que muestra avances importantes en elPrograma Nacional de Prevención, Control y Erradicación de la Brucelosis Bovina y el Programa Certificación de Hatos Libres de Brucella

Microscopic self-energy of 40{}^{40}Ca from the charge-dependent Bonn potential

The effects of short-range correlations on the nucleon self-energy in $^{40}$Ca are investigated using the charge-dependent Bonn (CDBonn) interaction. Comparisons are made with recent results for the self-energy of $^{40}$Ca derived from the dispersive optical-model (DOM). Particular emphasis is placed on the non-locality of the imaginary part of the microscopic self-energy which suggests that future DOM analyses should include this feature. In particular, data below the Fermi energy appear sensitive to the implied orbital angular momentum dependence of the self-energy. Quasiparticle properties obtained for the CDBonn interaction are substantially more mean-field-like than the corresponding DOM results with spectroscopic factors larger by about 0.2 e.g. Reaction cross sections obtained from the microscopic self-energy for scattering energies up to 100 MeV indicate that an adequate description of volume absorption is obtained while a considerable fraction of surface absorption is missing. The analysis of the non-locality of the imaginary part of the microscopic self-energy suggests that a simple gaussian provides an adequate description, albeit with rather large values for $\beta$, the non-locality parameter.Comment: 18 pages, 19 figures, 4 table

Molecular scale contact line hydrodynamics of immiscible flows

From extensive molecular dynamics simulations on immiscible two-phase flows, we find the relative slipping between the fluids and the solid wall everywhere to follow the generalized Navier boundary condition, in which the amount of slipping is proportional to the sum of tangential viscous stress and the uncompensated Young stress. The latter arises from the deviation of the fluid-fluid interface from its static configuration. We give a continuum formulation of the immiscible flow hydrodynamics, comprising the generalized Navier boundary condition, the Navier-Stokes equation, and the Cahn-Hilliard interfacial free energy. Our hydrodynamic model yields interfacial and velocity profiles matching those from the molecular dynamics simulations at the molecular-scale vicinity of the contact line. In particular, the behavior at high capillary numbers, leading to the breakup of the fluid-fluid interface, is accurately predicted.Comment: 33 pages for text in preprint format, 10 pages for 10 figures with captions, content changed in this resubmissio

Síntesis y estudio de las propiedades estructurales de zeolitas crecidas a partir del sistema NaOH+H2O+A* (A*= SiO2, Al) en un medio alcalino (pH > 10)

In this paper we present the synthesis of Zeolitesthrough the obtaining of a gel composed forthe mixture of alkaline and aluminosilicate solutes.We studied the kinetics of the structurationof zeolites taking into account the reactions A:NaOH+H2O+SiO2 and B: NaOH+H2O+Al. Thevalues of concentration used on each one of thesesolutes were 4.2 g (NaOH), 60- 20 ml (H2O forthe solutes A and B respectively), 6.0 g (SiO2) y 1,7(Al). For the resulting gel, which was gotten whenadding in a slowly way the solute B to the A one, weobtained a Ph equals 14. The synthesized zeoliteswere under thermic treatments of 120°C per cyclesfrom 8 to 10 hours. The structural properties withthe identification of the growing phases were studiedthrough the technic of X- ray diffraction changing2q in the interval 5-60°. From the spectrums ofXRD we observed a mainly predominance of thecrystal phase in the composition of Zeolita with anamorphous component. The presence of phasescoming from other minerals which have been theproducts of the reaction is reflected in the synthesisof the samples. We studied the morphology ofthe surface through scanning electron microscopy(SEM). Based on SEM images it is seen that someareas of the surface are led by isolated grains andcharacterized for values in the size of the grain atabout 20 mm.En este trabajo se presenta la síntesis de zeolitasmediante la obtención de un gel compuesto por lamezcla de soluciones alcalinas y aluminosilicatos.La cinética de formación de las zeolitas se estudióa partir de las reacciones A: NaOH+H2O+SiO2 yB: NaOH+H2O+Al. Los valores de concentraciónempleados en cada una de las soluciones fueron 4.2g (NaOH), 60-20 ml (H2O para las soluciones A yB respectivamente), 6.0 g (SiO2) y 1,7 (Al). Para elgel resultante de la zeolita obtenido al añadir lentamentela disolución B a la A se obtuvo un pH=14.Las zeolitas sintetizadas fueron sometidas a tratamientostérmicos de 120 ºC por ciclos de 8 a 10horas. Las propiedades estructurales junto con laidentificación de las fases de crecimiento fueron estudiadasmediante la técnica de difracción de rayosX (XRD), variando 2q en el rango entre 5-60º. Apartir de los espectros de XRD se observa un predominiode la fase cristalina en la composición dela zeolita acompañado de una componente amorfa.La presencia de fases de otros minerales, productosde la reacción, es evidenciada en el crecimientode las muestras. La morfología de la superficie fueestudiada por microscopia electrónica de barrido(SEM). A partir de las imágenes de SEM se observaque algunas regiones de la superficie son gobernadaspor granos aislados caracterizadas por valoresen el tamaño de grano alrededor de 20 nm

Numerical Investigation of Boundary Conditions for Moving Contact Line Problems

When boundary conditions arising from the usual hydrodynamic assumptions are applied, analyses of dynamic wetting processes lead to a well-known nonintegrable stress singularity at the dynamic contact line, necessitating new ways to model this problem. In this paper, numerical simulations for a set of representative problems are used to explore the possibility of providing material boundary conditions for predictive models of inertialess moving contact line processes. The calculations reveal that up to Capillary number Ca=0.15, the velocity along an arc of radius 10Li (Li is an inner, microscopic length scale! from the dynamic contact line is independent of the macroscopic length scale a for a.103Li , and compares well to the leading order analytical ‘‘modulated-wedge’’ flow field [R. G. Cox, J. Fluid Mech. 168, 169 (1986)] for Capillary number Ca,0.1. Systematic deviations between the numerical and analytical velocity field occur for 0.1168, 169 (1986)] is used as a boundary condition along an arc of radius R=10-2a from the dynamic contact line, agree well with those using two inner slip models for Ca\u3c0.1, with a breakdown at higher Ca. Computations in a cylindrical geometry reveal the role of azimuthal curvature effects on velocity profiles in this vicinity of dynamic contact lines. These calculations show that over an appropriate range of Ca, the velocity field and the meniscus slope in a geometry-independent region can potentially serve as material boundary conditions for models of processes containing dynamic contact lines

Spreading Dynamics of Polymer Nanodroplets

The spreading of polymer droplets is studied using molecular dynamics simulations. To study the dynamics of both the precursor foot and the bulk droplet, large drops of ~200,000 monomers are simulated using a bead-spring model for polymers of chain length 10, 20, and 40 monomers per chain. We compare spreading on flat and atomistic surfaces, chain length effects, and different applications of the Langevin and dissipative particle dynamics thermostats. We find diffusive behavior for the precursor foot and good agreement with the molecular kinetic model of droplet spreading using both flat and atomistic surfaces. Despite the large system size and long simulation time relative to previous simulations, we find no evidence of hydrodynamic behavior in the spreading droplet.Comment: Physical Review E 11 pages 10 figure