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

Sistemas de evaluación de los alumnos mediante test informatizados utilizando telefonía móvil

This paper describes a system for executing adaptive tests in mobile devices. Tests are generated in XML files using Test Editor that is a author tool integrated in AHA! system. These tests are interpreted by our system that can show to the user in theirs mobile devices such as mobile phone or PDA. Our test execution engine is a Midlet, that is a small Java application oriented to be executed in a mobile device. This application can execute classic or adaptive test of type activity (it can be executed all the times that students wants) or exam (it can be only executed one time). Studens have to identify with theirs logins the first time that they execute a test. The next times is not necessary due to it is stored in the RMS memory. In this memory, we also store the interface adaptable parameters such as the language, the font type, the number of screens in which the question will be shown, etc. Finally, after executing a test the obtained results are shonw to the students and they are also send it to the AHA! server by GPRS.Este artículo presenta un sistema para la ejecución de test adaptativos en dispositivos móviles. Los test son generados en forma de ficheros XML a través de la herramienta autor Test Editor que se encuentra integrada en el sistema AHA! y son interpretados por nuestro sistema que puede mostrarlos a los usuarios en su dispositivo móvil, ya sea teléfono móvil o PDA. Nuestro motor de ejecución de test es un Midlet que es una pequeña aplicación Java orientada a ser ejecutada en dispositivos móviles. Esta aplicación permite realizar test clásicos y adaptativos de tipo actividad y de tipo examen. Si la prueba es de tipo examen, ésta sólo podrá ser ejecutada una sola vez, en cambio si es de tipo actividad se podrá ejecutar tantas veces como se quiera. Los estudiantes deben de identificarse con su login la primera vez que ejecuta el test, ya que el resto de veces éste queda almacenado en memoria RMS. En esta memora tambien son almacenados los parámetros adaptables del interfaz, ya que los estudiantes podrán personalizar la configuración de el idioma, el tipo de fuente, el número de pantallas en que se muestran las preguntas, etc. Finalmente tras ejecutar un test los resultados obtenidos son mostrados a los estudiantes y son tambien enviados al servidor de AHA! a través de GPRS

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

Search for free-floating planetary-mass objects in the Pleiades

(Abridged) We aim at identifying the least massive population of the solar metallicity, young (120 Myr), nearby (133.5 pc) Pleiades star cluster with the ultimate goal of understanding the physical properties of intermediate-age, free-floating, low-mass brown dwarfs and giant planetary-mass objects, and deriving the cluster substellar mass function across the deuterium-burning mass limit at ~0.012 Msol. We performed a deep photometric and astrometric J- and H-band survey covering an area of ~0.8 deg^2. The images with completeness and limiting magnitudes of J,H ~ 20.2 and ~ 21.5 mag were acquired ~9 yr apart (proper motion precision of +/-6 mas/yr). J- and H-band data were complemented with Z, K, and mid-infrared magnitudes up to 4.6 micron coming from UKIDSS, WISE, and follow-up observations of our own. Pleiades member candidates were selected to have proper motions compatible with that of the cluster, and colors following the known Pleiades sequence in the interval J = 15.5-8.8 mag, and Z_UKIDSS - J > 2.3 mag or Z nondetections for J > 18.8 mag. We found a neat sequence of astrometric and photometric Pleiades substellar member candidates in the intervals J = 15.5-21.2 mag and ~0.072-0.008 Msol. The faintest objects show very red near- and mid-infrared colors exceeding those of field high-gravity dwarfs by >0.5 mag. The Pleiades photometric sequence does not show any color turn-over because of the presence of photospheric methane absorption down to J = 20.3 mag, which is about 1 mag fainter than predicted by the color-computed models. Pleiades brown dwarfs have a proper motion dispersion of 6.4-7.5 mas/yr and are dynamically relaxed at the age of the cluster. The Pleiades mass function extends down to the deuterium burning-mass threshold, with a slope fairly similar to that of other young star clusters and stellar associations.Comment: Accepted for publication in A&A. 16 page

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

KETpic-Matlab Toolbox for LaTeX High-Quality Graphical Artwork in Educational Materials on Bézier Curve Algorithms at a Master Level

This paper introduces a new toolbox to generate high-quality graphical artwork about the main algorithms for Bézier curves and related topics. The package has been implemented by the authors as a supporting middleware tool to generate educational materials for a computer-aided geometric design (CAGD) course at an advanced level (typically a Master/PhD course; even a senior course in some engineering degrees). Its primary goal is to instill geometric intuition in our students and help them develop critical thinking based on geometric reasoning for problem solving. We also aim at providing the instructors of such courses with a computer library to produce high-quality graphics for educational materials with a seamless integration into . In this regard, all graphical objects are encoded as plain source code that yields nice pictures after standard compilation. The application of this package to generate educational materials is discussed through six illustrative examples of interesting properties of the Bézier curves. They show that our package is very easy to use, supports many different graphical options, and fosters students’ creative geometric thinking with very little effort

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