Global three-dimensional flow of a neutron superfluid in a spherical shell in a neutron star

We integrate for the first time the hydrodynamic Hall-Vinen-Bekarevich-Khalatnikov equations of motion of a $^{1}S_{0}$-paired neutron superfluid in a rotating spherical shell, using a pseudospectral collocation algorithm coupled with a time-split fractional scheme. Numerical instabilities are smoothed by spectral filtering. Three numerical experiments are conducted, with the following results. (i) When the inner and outer spheres are put into steady differential rotation, the viscous torque exerted on the spheres oscillates quasiperiodically and persistently (after an initial transient). The fractional oscillation amplitude ($\sim 10^{-2}$) increases with the angular shear and decreases with the gap width. (ii) When the outer sphere is accelerated impulsively after an interval of steady differential rotation, the torque increases suddenly, relaxes exponentially, then oscillates persistently as in (i). The relaxation time-scale is determined principally by the angular velocity jump, whereas the oscillation amplitude is determined principally by the gap width. (iii) When the mutual friction force changes suddenly from Hall-Vinen to Gorter-Mellink form, as happens when a rectilinear array of quantized Feynman-Onsager vortices is destabilized by a counterflow to form a reconnecting vortex tangle, the relaxation time-scale is reduced by a factor of $\sim 3$ compared to (ii), and the system reaches a stationary state where the torque oscillates with fractional amplitude $\sim 10^{-3}$ about a constant mean value. Preliminary scalings are computed for observable quantities like angular velocity and acceleration as functions of Reynolds number, angular shear, and gap width. The results are applied to the timing irregularities (e.g., glitches and timing noise) observed in radio pulsars.Comment: 6 figures, 23 pages. Accepted for publication in Astrophysical Journa

Avalanche dynamics of radio pulsar glitches

We test statistically the hypothesis that radio pulsar glitches result from an avalanche process, in which angular momentum is transferred erratically from the flywheel-like superfluid in the star to the slowly decelerating, solid crust via spatially connected chains of local, impulsive, threshold-activated events, so that the system fluctuates around a self-organised critical state. Analysis of the glitch population (currently 285 events from 101 pulsars) demonstrates that the size distribution in individual pulsars is consistent with being scale invariant, as expected for an avalanche process. The waiting-time distribution is consistent with being exponential in seven out of nine pulsars where it can be measured reliably, after adjusting for observational limits on the minimum waiting time, as for a constant-rate Poisson process. PSR J0537$-$6910 and PSR J0835$-$4510 are the exceptions; their waiting-time distributions show evidence of quasiperiodicity. In each object, stationarity requires that the rate $\lambda$ equals $- \epsilon \dot{\nu} /$, where $\dot{\nu}$ is the angular acceleration of the crust, $$ is the mean glitch size, and $\epsilon\dot{\nu}$ is the relative angular acceleration of the crust and superfluid. There is no evidence that $\lambda$ changes monotonically with spin-down age. The rate distribution itself is fitted reasonably well by an exponential for $\lambda \geq 0.25 {\rm yr^{-1}}$. For $\lambda < 0.25 {\rm yr^{-1}}$, its exact form is unknown; the exponential overestimates the number of glitching pulsars observed at low $\lambda$, where the limited total observation time exercises a selection bias.Comment: Accepted for publication in the Astrophysical Journa

Sustitución de ingredientes proteicos y su efecto sobre parámetros productivos en toros de Paraguay

In order to determine the effect of substituting protein ingredients on production parameters (daily weight gain, feed intake and feed conversion) in confined bulls, bovine animals were selected, grouped into 2 lots in a random and homogeneous manner, composed of nelore-type bulls between 1 and 3 years of age: Treatment 1 (T1) 51 bulls with feed based on corn mockery and Treatment 2 (T2) 51 bulls with feed based on soybean expeller. The initial weighing was carried out at the entrance of the animals, after which two weighings were carried out, one at 45 days and the other at 90 days. At the end of the period, the weights of each group were compared. The results obtained based on the daily weight gain were subjected to the T-Student statistical method, observing significant differences (p&lt;0.05), in favor of T2 in relation to T1. Daily weight gain was 1.47 kg/day at T1, 1.52 kg/day at T2, with daily consumption at T1 being 16.8 kg and 17.4 kg at T2, in terms of feed conversion at T1 it was 6.75 kg and at T2 it was 6.82 kg.Con el objetivo de determinar el efecto de la sustitución de ingredientes proteicos sobre parámetros productivos en toros confinados (ganancia diaria de peso, consumo y conversión alimenticia), fueron seleccionados animales de la especie bovina, agrupados en 2 lotes de forma aleatoria y homogénea, compuestos por toros tipo nelore de entre 1 a 3 años de edad: Tratamiento 1 (T1) 51 toros con alimento a base de burlanda de maíz y Tratamiento 2 (T2) 51 toros con alimento a base de expeller de soja. El pesaje inicial se realizó a la entrada de los animales. Posterior a eso se procedió a dos pesajes, uno a los 45 días y otro a los 90 días. Al final del período se realizó la comparación de los pesos de cada grupo. Los resultados obtenidos en base a la ganancia diaria de peso fueron sometidos al método estadístico T-Student, observándose diferencias significativas (p&lt;0,05) a favor del T2 en relación al T1. La ganancia diaria de peso fue en el T1 de 1,47 kg/día y en el T2 1,52 kg/día, siendo el consumo diario en el T1 de 16,8 kg y en el T2 17,4 kg. En cuanto a la conversión alimenticia en el T1 fue de 6,75 kg y en el T2 fue de 6,82 kg

Fortaleciendo los sistemas tradicionales de producción de semilla en los Andes en Perú.

Los cultivos alimenticios en el Perú han estado históricamente asociados a la pequeña agricultura andina, caracterizada por predios muy pequeños (<3ha), tecnificación tradicional y producción destinada principalmente al autoconsumo y una pequeña proporción para la venta y producción de semilla. El Centro Internacional de la Papa (CIP) a través de su programa Papa Andina/INCOPA promovió una serie de innovaciones que han permitido revalorizar la biodiversidad de la papa y organizar cadenas productivas inclusivas para articular a pequeños productores pobres alto andinos a nuevos mercados. Sin embargo, esta innovación generó demanda por semilla de variedades nativas con potencial de mercado, la cual no ha podido ser satisfecha debido a que el sistema formal de semilla no abastece la demanda interna y las variedades nativas no han sido priorizadas por dicho sistema. Como alternativa, los proyectos del CIP como InnovAndes (Junín y Huancavelica) y McKnight (Pasco), están promoviendo esquemas no convencionales como una alternativa flexible para mejorar los sistemas tradicionales de producción de semilla y responder a la demanda de los pequeños productores. En ambos casos, en las comunidades participantes se organizaron comités de gestión de semillas, que fueron capacitados en técnicas de multiplicación de semilla e identificación de plagas para tener a su cargo la producción de semilla básica en campos semilleros e invernaderos empleando la técnica de selección positiva. La capacitación se realizó a través de escuelas de campo de agricultores (ECA) semilleristas. Como resultado de la intervención, del Proyecto McKnight en las comunidades de La Quinua y Quichas (Pasco) se logró reducir en más del 92% la incidencia de virus (PVX y PVS), enfermedades (P. infestans) e insectos (Epitrix spp, y Diabrótica spp) que afectan la calidad de la semilla, lográndose aumentar el rendimiento promedio de tubérculos en 53%. En este proyecto, el comité de gestión de semillas se constituyó como empresa y cuentan con un invernadero de aeroponia para producir semilla prebásicaa bajo costo, habiendo producido hasta la fecha 54,000 tuberculillos de 6 variedades nativas. En el marco del proyecto Innovandes, los productores de Chicche y Pomamanta (Junín) aprendieron la técnica convencional de propagación y multiplicación de semilla pre-básica en sus respectivos invernaderos. En 2011 la producción fue en total 20,574 tuberculillos de variedades nativas con demanda en el mercado, con lo que han constituido un fondo rotatorio de semilla de las variedades Leona y Cceccorani de uso en gastronomía y la industria, respectivamente. Los resultados indican que la producción de semilla pre-básica en combinación con la técnica de selección positiva ayudará a gestar un mercado regional de semilla de calidad, con posibilidades de evolucionar hacia un esquema o modelo no convencional, similar al de semilla de calidad declarada (QDS)

Average stresses and force fluctuations in non-cohesive granular materials

A lattice model is presented for investigating the fluctuations in static granular materials under gravitationally induced stress. The model is similar in spirit to the scalar q-model of Coppersmith et al., but ensures balance of all components of forces and torques at each site. The geometric randomness in real granular materials is modeled by choosing random variables at each site, consistent with the assumption of cohesionless grains. Configurations of the model can be generated rapidly, allowing the statistical study of relatively large systems. For a 2D system with rough walls, the model generates configurations consistent with continuum theories for the average stresses (unlike the q-model) without requiring the assumption of a constitutive relation. For a 2D system with periodic boundary conditions, the model generates single-grain force distributions similar to those obtained from the q-model with a singular distribution of q's.Comment: 18 pages, 10 figures. Uses aps,epsfig,graphicx,floats,revte

Computed tomography porosity and spherical indentation for determining cortical bone millimetre-scale mechanical properties

The cortex of the femoral neck is a key structural element of the human body, yet there is not a reliable metric for predicting the mechanical properties of the bone in this critical region. This study explored the use of a range of non-destructive metrics to measure femoral neck cortical bone stiffness at the millimetre length scale. A range of testing methods and imaging techniques were assessed for their ability to measure or predict the mechanical properties of cortical bone samples obtained from the femoral neck of hip replacement patients. Techniques that can potentially be applied in vivo to measure bone stiffness, including computed tomography (CT), bulk wave ultrasound (BWUS) and indentation, were compared against in vitro techniques, including compression testing, density measurements and resonant ultrasound spectroscopy. Porosity, as measured by micro-CT, correlated with femoral neck cortical bone’s elastic modulus and ultimate compressive strength at the millimetre length scale. Large-tip spherical indentation also correlated with bone mechanical properties at this length scale but to a lesser extent. As the elastic mechanical properties of cortical bone correlated with porosity, we would recommend further development of technologies that can safely measure cortical porosity in vivo. Introductio

Preliminary data on the ovarian histological structures observed in black hakes (M. polli and M. senegalensis) off Mauritania

The black hakes, Merluccius polli and M. senegalensis, are target species of a trawl Spanish fleet in Mauritanian waters. M. polli is a deep-water hake while M. senegalensis shows a shallower distribution. Both species are mixed in the landings, although the deeper hake totals a greater fraction (85%) of the catch due to the fishing strategy of the trawl fleet. The female gonads of both hakes were collected during an experimental survey carried out in the Mauritanian EEZ. Mature ovaries were examined from the start of the reproductive season in this area. Ovaries were processed by a standard histological technique. Histological characteristics of ovarian tissues and oocyte stages were studied by light microscopy. The ovaries of black hakes showed various stages of oocyte development from the small sized, chromatin nuclear and perinucleolar oocytes, and the medium sized, cortical alveoli and vitellogenic oocytes. This last stage presents yolk granules occupying the cytoplasm at different levels. In the case of M. senegalensis, the presence of large sized oocytes with early migration of the nucleus to the animal pole, as well as fusion of oil droplets indicate maturation and imminent spawning, thus, indicating an earlier spawning than M. polli. Furthermore, postovulatory follicles observed in M. senegalensis indicate a recent batch spawning episode. This result is concordant with the values of GSI obtained for both species in these waters. The reproductive period extends from October to Mars with a defined peak in December - January for females of both hakes, although the shallower species, M. senegalensis, shows an earlier spawning in this study. Atretic stages were observed, but their incidence was low because the sampling corresponds to the beginning of the spawning period. The species are multiple batch spawners as suggested by their oocyte size frequency distribution in the ovary. The present study is a first approach to ovarian histology of M. polli and M. senegalensis, and intended to provide basic knowledge for further detailed studies on the reproductive biology of these species, essential for an adequate assessment of this stock.Instituto Español de Oceanografía (IEO

Equation of state and transport processes in self--similar spheres

We study the effect of transport processes (diffusion and free--streaming) on a collapsing spherically symmetric distribution of matter in a self--similar space--time. A very simple solution shows interesting features when it is matched with the Vaidya exterior solution. In the mixed case (diffusion and free--streaming), we find a barotropic equation of state in the stationary regime. In the diffusion approximation the gravitational potential at the surface is always constant; if we perturb the stationary state, the system is very stable, recovering the barotropic equation of state as time progresses. In the free--streaming case the self--similar evolution is stationary but with a non--barotropic equation of state.Comment: 9 pages, 2 figure

Análise proteômica do estresse hídrico em cafeeiro.

Déficit hídrico é um dos fatores ambientais mais importantes para a diminuição da produtividade do cafeeiro, tanto no Brasil quanto em outros países produtores. O estabelecimento de estratégias para obtenção de cultivares tolerantes ao estresse hídrico depende da compreensão das respostas biológicas ao nível genético, molecular e bioquímico. Para estudar a resposta ao estresse hídrico no gênero Coffea, foi estabelecida uma rede de pesquisa em proteômica (PROTEOPAR ? Programa Proteoma do Paraná) constituída de oito laboratórios. Quatro genótipos de Coffea, com diferentes respostas fisiológicas à seca, foram analisados: C. canephora (Clone 14, tolerante e Clone 109A, sensível) e C. arabica (BA10, tolerante e Geisha, sensível). Proteínas foram extraídas de folhas e raízes de plantas (18 meses de idade) mantidas em casa-de-vegetação, utilizando-se o método de SDS-Fenol modificado. Os regimes hídricos constituíram-se dos seguintes tratamentos: controle irrigado, estresse hídrico severo (-4,0 MPa de potencial de água) e recuperação pós-estresse (36 horas após irrigação). Os extratos protéicos foram distribuídos aos laboratórios do PROTEOPAR para obtenção e análise do padrão de expressão protéica diferencial via eletroforese bidimensional. O método de identificação de proteínas PMF (?Peptide mass fingerprinting?) foi aplicado utilizando-se um espectrômetro de massa (MS) do tipo MALDI-TOF e comparando os espectros de digestão tríptica contra bancos de dados baseados em ESTs de Coffea

Force distributions in 3D granular assemblies: Effects of packing order and inter-particle friction

We present a systematic investigation of the distribution of normal forces at the boundaries of static packings of spheres. A new method for the efficient construction of large hexagonal-close-packed crystals is introduced and used to study the effect of spatial ordering on the distribution of forces. Under uniaxial compression we find that the form for the probability distribution of normal forces between particles does not depend strongly on crystallinity or inter-particle friction. In all cases the distribution decays exponentially at large forces and shows a plateau or possibly a small peak near the average force but does not tend to zero at small forces.Comment: 9 pages including 8 figure