Texture Evolution of AZ31 Magnesium Alloy Sheet at High Strain Rates

In the current contribution the mechanical behaviour at high strain rates of AZ31 magnesium alloy sheet is studied. Uniaxial deformation properties were studied by means of tensile split Hopkinson pressure bar (SHPB) at different temperatures. The influence of the strain rate and temperature on the deformation mechanisms was investigated by means of electron backscatter diffraction (EBSD) and neutron diffraction. It is shown that twinning plays an important role on high strain rate deformation of this alloy, even at elevated temperatures. Significant evidence of prismatic slip as a deformation mechanism is observed, also at warm temperatures, leading to the alignment of directions with the tensile axis and to a spread of the intensities of the basal pole figure towards the in-plane direction perpendicular to the tensile axis. The rate of decrease of the CRSS of non-basal systems is observed to be slower than at quasi-static rates. Secondary twinning and pyramidal slip were also outlined for some conditions. At warm temperatures, in contrast to quasi-static range, a generalized dynamic recrystallization is not observed. Moreover, the activation of rotational recrystallization mechanisms is reporte

Twinning and grain subdivision during dynamic deformation of a Mg AZ31 sheet alloy at room temperature

The microstructural evolution of an AZ31 rolled sheet during dynamic deformation at strain rates of ∼103 s−1 has been investigated by electron backscatter diffraction, X-ray and neutron diffraction. The influence of orientation on the predominant deformation mechanisms and on the recovery processes taking place during deformation has been systematically examined. The results have been compared with those corresponding to the same alloy tested quasi-statically under equivalent conditions. It has been found that strain rate enhances the activation of extension twinning dramatically, while contraction and secondary twinning are not significantly influenced. The polarity of extension twinning is even reversed in some grains under selected testing conditions. Significant grain subdivision by the formation of geometrically necessary boundaries (GNBs) takes place during both quasi-static and dynamic deformation of this AZ31 alloy. It is remarkable that GNBs of high misorientations form even at the highest strain rates. The phenomenon of recovery has been found to be orientation dependen

Development of the technique of isoelectricfocusing and immunodetection of immunoglobulin A in the healthcare context as support for the diagnosis of Multiple Sclerosis

Motivation: Multiple sclerosis (MS) is characterized by demyelination and subsequent degeneration of myelin sheaths that line the axons of neurons, producing multifocal and temporarily dispersed damage to the central nervous system (CNS) [1] that leads to neuronal damage and axonal loss [2]. MS is a complex disease in which the exact etiology remains unknown, although our current understanding of the natural history of MS and its immunopathogenesis points to an immune deregulation resulting from an interaction between genetic predispositions and environmental factors [2]. Given this uncertainty, there is a need for the identification of biomarkers in both cerebrospinal fluid and peripheral blood that help us to have a more complete view of the disease, and at the same time could contribute to a faster and more accurate diagnosis. This project arises from the importance and need to study immunoglobulin A as a biomarker for MS. Methods: Isoelectric focusing is one of the most powerful techniques used to solve complex mixtures of proteins [2]. The main objective of this project is the development of the isoelectroenfocusing and immunodetection technique for oligoclonal bands of immunoglobulin A and the IgA reduction protocol [3][4] to establish a subsequent relationship between patients diagnosed with MS and intrathecal secretion of immunoglobulin A. Results: For the implementation of the technique, a set of cerebrospinal fluid (CSF) samples previously extracted by lumbar puncture were selected, presenting the patient with a diagnostic suspicion of demyelinating disease, and presenting a high quantification of intrathecal secretion of IgA, routinely carried out in the Clinical Biochemistry Unit, immunology laboratory. A total of 23 samples were selected based on IgA concentrations in both CSF and serum. Conclusions: It should be noted that today the CSF remains the most interesting fluid for the study of degenerative neurological diseases. The CSF is the best representative of the clinical manifestations that are confined to the central nervous system, hence its characterization is, increasingly, of high interest for a more accurate diagnosis. With this set-up it is intended to give new information to the clinician to help diagnose the disease. Its value as a marker of the disease will be derived from subsequent observations and studies that clinicians perform in their cohort

Comunicación corta. Rhizoctonia solani, agente causal de la muerte de plántulas de acelga en España

During September 2011, post-emergence damping off of Swiss chard (Beta vulgaris subsp. cicla L.) was observed in a greenhouse in Villa del Prado (Spain). About 20% of the seedlings showed damping off symptoms. Lesions were initially water soaked, dark brown necrosis of crown tissue, irregular in shape and sunken in appearance on large plants, causing the infected seedlings to collapse and eventually die. Rhizoctonia solani was isolated consistently from symptomatic plants. After morphological and molecular identification of the isolates, pathogenicity was tested by placing agar plugs of four isolates adjacent to the stem at the three or four true leaf stage. In inoculated plants, brown crown and stem necrosis occurred while control plants did not show disease symptoms. Pathogenicity using non-germinated seeds was also tested. All four isolates produced extensive damping off when inoculated on non-germinated seeds. To our knowledge, this is the first report of damping off of Swiss chard caused by R. solani in Europe.En el mes de septiembre de 2011, se observó muerte de plántulas en acelgas cultivadas en un invernadero en Villa del Prado (España). Cerca del 20% de los semilleros mostraban síntomas de caída de plántulas. Las lesiones iniciales tenían un aspecto húmedo y consistían en una necrosis del tejido de la corona de color marrón oscuro, de bordes irregulares y deprimidos en las plantas adultas, produciendo el colapso de las plántulas y, ocasionalmente, la muerte de las mismas. Rhizoctonia solani se aisló de manera consistente de las plantas sintomáticas. Tras una identificación morfológica y molecular, la patogenicidad de los aislados se probó colocando discos de agar adyacentes al tallo de la planta en estados de tres o cuatro hojas verdaderas. En las plantas inoculadas se observó un oscurecimiento de la corona y la necrosis del tallo en todos los casos, síntomas que no mostraron las plantas control. Por otro lado, se comprobó la patogenicidad de los aislados en semillas no germinadas. Los cuatro aislados produjeron muerte de plántulas cuando se inocularon en semillas no germinadas. Hasta donde hemos podido comprobar, este trabajo parece ser la primera cita de muerte de plántulas de acelga causada por R. solani en Europa

Habitat Preferences of Breeding Amphibians in Eastern Spain

The aim of this research was to determine the reproductive habitat preferences of several species of amphibians in eastern Spain. We recorded amphibia presence/absence and measured biotic and abiotic variables at 67 ponds in a 43.5 km2 area representing a wide variety of aquatic ecosystems, such as temporary and semipermanent cisterns, drinking troughs, and natural and artificial ponds, all of various sizes and depths. We used this information to predict occupancy using Generalized Linear Models. We built models for the Iberian Ribbed Newt (Pleurodeles waltl), Iberian Green Frog (Pelophylax perezi), Common Midwife Toad (Alytes obstetricans), Natterjack Toad (Epidalea calamita), and Mediterranean Parsley Frog (Pelodytes hespericus). We also found Common Toad (Bufo spinosus) and Spadefoot Toad (Pelobates cultripes) but did not build models for them. The variables that explained occupancy were species specific, with depth and, especially, the type of substratum playing key roles in most of them. Type of substratum reflected pond age and was represented by hard substratum (associated with new artificial ponds and structures), hard substratum covered by soft sediment (associated with old artificial ponds and structures), and soft substratum (associated with old natural ponds). The differences among the species in occupancy models indicate that species-specific management actions may be necessary to preserve the amphibian community in the long term

Parameterized optimized effective potential for atoms

The optimized effective potential equations for atoms have been solved by parameterizing the potential. The expansion is tailored to fulfill the known asymptotic behavior of the effective potential at both short and long distances. Both single configuration and multi configuration trial wave functions are implemented. Applications to several atomic systems are presented improving previous works. The results here obtained are very close to those calculated in either the Hartree-Fock and the multi configurational Hartree-Fock framework.Comment: 8 pages, 3 figure

Identifying Ultra-Cool Dwarfs at Low Galactic Latitudes: A Southern Candidate Catalogue

We present an Ultra-Cool Dwarf (UCD) catalogue compiled from low southern Galactic latitudes and mid-plane, from a cross-correlation of the 2MASS and SuperCOSMOS surveys. The catalogue contains 246 members identified from 5042 sq. deg. within 220 deg. <= l <= 360 deg. and 0 deg. < l <= 30 deg., for |b| <= 15 deg. Sixteen candidates are spectroscopically confirmed in the near-IR as UCDs with spectral types from M7.5V to L9. Our catalogue selection method is presented enabling UCDs from ~M8V to the L-T transition to be selected down to a 2MASS limiting magnitude of Ks ~= 14.5 mag. This method does not require candidates to have optical detections for catalogue inclusion. An optimal set of optical/near-IR and reduced proper-motion selection criteria have been defined that includes: an Rf and Ivn photometric surface gravity test, a dual Rf-band variability check, and an additional photometric classification scheme to selectively limit contaminants. We identify four candidates as possible companions to nearby Hipparcos stars -- observations are needed to identify these as potential benchmark UCD companions. We also identify twelve UCDs within a possible distance 20 pc, three are previously unknown of which two are estimated within 10 pc, complimenting the nearby volume-limited census of UCDs. An analysis of the catalogue spatial completeness provides estimates for distance completeness over three UCD MJ ranges, while Monte-Carlo simulations provide an estimate of catalogue areal completeness at the 75 per cent level. We estimate a UCD space density of Rho (total) = (6.41+-3.01)x10^3/pc^3 over the range of 10.5 <= MJ ~< 14.9, similar to values measured at higher Galactic latitudes (|b| ~> 10 deg.) in the field population and obtained from more robust spectroscopically confirmed UCD samples.Comment: MNRAS accepted April 2012. Contains 30 figures and 11 tables. Tables 2 and 6 to be published in full and on-line only. The on-line tables can also be obtained by contacting the author

Agresión sexual intrafamiliar y extrafamiliar y su asociación con el consumo de alcohol

OBJETIVO: Analizar la prevalencia de las agresiones sexuales intrafamiliares y extrafamiliares en adolescentes del Perú y su asociación con el consumo de alcohol. MÉTODOS: Se utilizó un muestreo probabilístico bietápico y estratificado para seleccionar estudiantes varones y mujeres de educación secundaria de todo el Perú. Los datos de 54,756 estudiantes que incluían información demográfica, sobre consumo de alcohol y drogas, y agresión sexual fueron incluidos en el estudio. En el análisis estadístico se consideró el muestreo complejo y se condujeron dos análisis independientes por el tipo de agresión sexual (intrafamiliar y extrafamiliar), estratificado por el sexo de la víctima. RESULTADOS: La prevalencia de vida de las agresiones sexuales intrafamiliares (5.4%, IC95% 5.0–5.8) fue similar al de las agresiones extrafamiliares (6.1%, IC95% 5.6–6.6). El consumo de alcohol en el último año se asoció con las agresiones sexuales intrafamiliares y extrafamiliares que ocurrieron en el mismo periodo después de ajustar por los factores de confusión. El consumo de alcohol en el último año se asoció a las formas no físicas y físicas de agresión sexuales intrafamiliares y extrafamiliares en el análisis desagregado por tipo de agresión. El consumo de alcohol en el último año se asoció con las violaciones sexuales extrafamiliares sólo entre las mujeres (ORa = 2.8; IC95% 1.3–5.9). CONCLUSIONES: La agresión sexual de adolescentes mujeres y varones por miembros familiares es una forma frecuente de victimización que se asocia al consumo de alcohol en el Perú. Es importante indagar por esta forma de victimización en adolescentes, especialmente los que consumen alcohol.OBJECTIVE: Analyze the prevalence of intrafamilial and extrafamilial sexual assault in adolescents of Peru and its association with alcohol consumption. METHODS: We used a two-step and stratified probabilistic sampling to select male and female students in secondary education from all over Peru. The study included data from 54,756 students with information on demographics, alcohol and drug use, and sexual assault. The statistical analysis considered the complex sampling and we conducted two independent analyses by type of sexual assault (intrafamilial and extrafamilial), stratified by the sex of the victim. RESULTS: The prevalence of life of intrafamilial sexual assaults (5.4%, 95%CI 5.0–5.8) was similar to that of extrafamilial sexual assaults (6.1%, 95%CI 5.6–6.6). Alcohol consumption in the past year was associated with intrafamilial and extrafamilial sexual assaults that occurred in the same period after adjusting for confounders. Alcohol consumption in the past year was associated with non-physical and physical forms of intrafamilial and extrafamilial sexual assaults in the disaggregated analysis by type of assault. Alcohol consumption in the past year was associated with extrafamilial rape only among females (ORa = 2.8; 95%CI 1.3–5.9). CONCLUSIONS: Sexual assault against adolescent males and females by family members is a frequent form of victimization that is associated with alcohol consumption in Peru. It is important to examine this form of victimization among adolescents, especially those who consume alcohol