Theory of Nonequilibrium Spin Transport and Spin Transfer Torque in Superconducting-Ferromagnetic Nanostructures

Spin transport currents and the spin-transfer torques in voltage-biased superconducting-ferromagnetic nanopillars (SFNFS point contacts) are computed. We develop and implement an algorithm based on the Ricatti formulation of the quasiclassical theory of superconductivity to solve the time-dependent boundary conditions for the nonequilibrium Green's functions for spin transport through the ferromagnetic interfaces. A signature of the nonequilibrium torque is a component perpendicular to the plane spanned by the two ferromagnetic moments. The perpendicular component is absent in normal-metal-ferromagnetic nanopillars (NFNFN) contacts, but is shown to have the same order of magnitude as the in-plane torque for non-equilibrium SFNFS contacts. The out-of-plane torque is due to the rotation of quasiparticle spin by the exchange fields of the ferromagnetic layers. In the ballistic limit the equilibrium torque is related to the spectrum of spin-polarized Andreev bound states, while the {\sl ac} component, for small bias voltages, is determined by the nearly adiabatic dynamics of the Andreev bound states. The nonlinear voltage dependence of the non-equilibrium torque, including the subharmonic gap structure and the high-voltage asymptotics, is attributed to the interplay between multiple Andreev reflections, spin filtering and spin mixing. These properties of spin angular momentum transport may be exploited to control the state of nanomagnets.Comment: 15 pages, 14 figure

Spikes in Cosmic Crystallography II: Topological Signature of Compact Flat Universes

We study the topological signature of euclidean isometries in pair separations histograms (PSH) and elucidate some unsettled issues regarding distance correlations between cosmic sources in cosmic crystallography. Reducing the noise of individual PSH's using mean pair separations histograms we show how to distinguish between topological and statistical spikes. We report results of simulations that evince that topological spikes are not enough to distinguish between manifolds with the same set of Clifford translations in their covering groups, and that they are not the only signature of topology in PSH's corresponding to euclidean small universes. We also show how to evince the topological signature due to non-translational isometries.Comment: 15 pages, 5 figures, LaTeX2e; Added 2 references and inserted clarifying details. To appear in Phys. Lett. A (2000) in the present for

Performance analysis of pressurized irrigation systems operating on-demand using flow-driven simulation models

On-demand pressurized irrigation systems are designed to deliver water with the flow rate and pressure required by the farm irrigation systems, sprinkling or micro-irrigation, and respecting the time, duration and frequency decided by the farmers. Due to the variation in farm demand along the season and the day, a large spatial and temporal variability of flow regimes occurs in these systems, which may affect the performance of the farm systems and the yields of the irrigated crops. Therefore, there is a need to analyse those systems to identify and solve performance problems. In this research, two simulation models for the analysis of irrigation systems operating on-demand, ICARE and AKLA, are used and compared to assess the hydraulic performance of the irrigation network of the Lucefecit Irrigation System, in Southern Portugal. ICARE assesses the global performance of the irrigation system through the indexed characteristic curves, while AKLA provides for the identification of the relative pressure deficit and reliability at every hydrant. Both models adopt a flow-driven analysis approach, performing the analysis for multiple flow regimes. To support the hydraulic characterization of the system and for calibration of the steadystate hydraulic model, field measurements were performed at selected nodes of the network, including four hydrants. The analysis with ICARE does not provide for a sufficient identification of problems. In fact, poor performance is indicated when a few hydrants operate below the minimum pressure set at design. Differently, the analysis with AKLA, applied at the hydrant level, shows that the performance of the Lucefecit system is generally acceptable. AKLA identifies which hydrants operate below the required pressure and, therefore, allows to support any eventual related improvement. Results show that the performance of the system highly improved when changing the piezometric elevation from 260 to 265m a.s.l. However, this improvement is not sufficient because three hydrants still have high relative pressure deficit and low reliability. Solutions for those hydrants require increasing diameters of network pipes supplying them

Efecto del peso al sacrificio y de la raza en la calidad instrumental y sensorial de la carne de cabritos lechales

Se utilizaron 141 cabritos de 5 razas españolas a dos pesos de sacrificio y se determinó la calidad instrumental y sensorial de su carne. La influencia del peso al sacrificio es, presumiblemente, muy importante sobre la calidad de la carne, pero este efecto debe ser valorado para cada raza. Aunque la carne del cabrito más ligero tuvo mayores valores en la fuerza de compresión, en el análisis sensorial esta carne fue descrita como más tierna y jugosa

Spanish marketing chain for kid’s meat: from breeder to wholesale

Se preguntó a 350 ganaderos de Andalucía, Aragón, Extremadura y castilla-La Mancha y a 350 entradores de Andalucía, Aragón, Madrid, Cataluña y Comunidad Valenciana, acerca de la manera de comprar y vender cabritos o su carne. Las zonas de producción no coinciden con las de comercialización y consumo y existen grandes diferencias entre regiones en cuanto al tamaño de las explotaciones. La distancia más frecuente entre explotación y matadero fue de 300 Km. En general, los ganaderos venden más caro y obtienen mayor margen de ganancia por el cabrito que por el cordero. Los entradores compran y venden más caro el cabrito que el cordero. La carnicería tradicional y la restauración son los destinos mayoritarios de venta de esta carne. La cadena de comercialización se complica cuando interviene una sala de despiece tras el entrador. La forma predominante de venta es la canal entera y cuando es por piezas, la pierna es la pieza más demandada. El consumo es estacional y está asociado a celebraciones. Farmers and wholesalers from different Spanish regions were enquired about the way in which they buy or sale kids or kid’s meat. Productions areas did not match with marketing points. There were great differences between regions in the farms’ size of the farms. The most frequent distance from farm to the slaughterhouse was 300 Km. Farmers sold more expensive and they obtained higher profit margin with kids than with lambs. Wholesalers buy and sold more expensive kid’s meat than lamb. Traditional butchers’ shops and restaurants were the main wholesalers’ customs. Marketing chain became more complex by the intervention of a quartering agent. The main way in which meat was sold was as whole carcasses. When they were sold by pieces, leg was the most demanded one. Kid’s meat presented a seasonal consumption, associated to holidays and celebrations

Características de la canal de cabritos de cinco razas españolas

En el presente estudio se han sacrificado 136 cabritos machos de dos niveles de peso para caracterizar de forma conjunta las canales de las razas Blanca Andaluza, Negra Serrana-Castiza, Blanca Celtibérica, Pirenaica y Moncaína. Se han observado diferencias significativas entre todas las razas en las variables de conformación estudiadas excepto en el perímetro de grupa y el índice de compacidad de la canal. La interacción peso-raza fue altamente significativa en las variables engrasamiento y ancho de grupa. EI rendimiento de la canal no fue significativa entre pesos pero si entre razas. En todas las variables con el aumento de peso aumentaron también los valores

Relationships between head-out aquatic exercise kinematics and musical cadence: analysis of the side kick

Background: Head-out aquatic exercises became one of the most popular physical activities within the health primarily and thirdly prevention system. Music is seen as one of the most important aspects when conducting head-out aquatic exercise sessions. Research question: Is there any relationship between musical cadence and the kinematic behaviour when performing aerobic head-out aquatic exercises? It was hypothesized that an increase in music cadence will would impose a decrease of the segment range of motion. Type of study: Experimental, prospective. Methods: Six young and clinically healthy women with at least one year of experience conducting head-out aquatic classes were videotaped in the frontal plane, with a pair of cameras providing a double projection (above and below the water surface). Subjects performed an incremental protocol of five bouts (120b.min-1, 135b.min-1, 150b.min-1, 165b.min-1 and 180b.min-1) with 16 full cycles of the “side kick” exercise. Data processing and calculation of segmental (i.e. hands and feet) and anatomical landmark (i.e. centre of mass) were performed using the software Ariel Performance Analysis System and applying the DLT algorithm. Results: There was a decrease in the cycle period during the incremental protocol. The relationships between the segmental lateral and vertical displacements with the musical cadence were not significant. The segmental velocities on the lateral and vertical components showed significant increases throughout the incremental protocol. Conclusions: The data suggest that segmental velocity increases with increasing cadence, reducing the cycle period and maintaining the segmental displacements

Head-out aquatic exercise “sailor’s jigs” kinematics at increasing musical cadence

The aim of this study was to analyze the relationships between “Sailor’s jigs” kinematic and increasing music cadence. Six young women with at least one year of experience conducting this type of head-out aquatic programs, with no kind of skeletal muscle injury reported on the last six months and non-pregnant were evaluated. The exercise was recorded on video, in the frontal plane, using a pair of cameras, enabling a double projection, from above and underwater body motions, at five increasing cadences (120 b.min-1, 135 b.min-1, 150 b.min-1, 165 b.min-1 and 180 b.min-1). Images were thereafter digitized in specific software (Ariel Performance Analysis Systems). The cycle period decreased through the incremental protocol. Cycle period decrease is done decreasing joints range of motion and increasing the limbs segmental velocity as well. Although these combined kinematical strategy, a deeper analysis reveals that subjects decrease the cycle period mainly decreasing the range of motions