Prospects for the detection of GRBs with HAWC

The observation of Gamma Ray Bursts (GRBs) with very-high-energy (VHE) gamma rays can provide understanding of the particle acceleration mechanisms in GRBs, and can also be used to probe the extra-galactic background light and place constraints on Lorentz invariance violation. We present prospects for GRB detection by the ground-based HAWC (High Altitude Water Cherenkov) gamma-ray observatory. We model the VHE spectrum of GRBs by extrapolating observations by Fermi LAT and other observatories to higher energies. Under the assumption that only e-pair production associated with extra-galactic background light is responsible for high-energy cutoffs in the spectrum, we find that HAWC will have a detection rate as high as 1.65 GRBs/year. Most of the sensitivity of HAWC to GRBs is derived from short-hard GRBs during the prompt phase. We explore the possibility of universal high-energy cutoffs in GRB spectra and find that the GRB detection rate by HAWC should be at least half of this figure as long as the typical intrinsic cutoff is above 200-300 GeV in the rest frame

Chemical weathering of the volcanic soils of Isla Santa Cruz (Galápagos Islands, Ecuador)

We present a study on weathering of volcanic soils using 43 profiles (131 horizons) sampled in Santa Cruz Island (Galapagos Islands). Several weathering indices, based on chemical composition, are used. Since the geological material is highly homogeneous the intensity of weathering is mostly related to climatic conditions controlled by topography. There is a gradient of increasing weathering from the arid conditions predominant in the coast to elevations of 400-500 m a.s.l. where much more humid conditions prevail

The impact of cultural dissonance and acculturation orientations on immigrant students' academic performance

Indexación: Scopus; Scielo; Redalyc.Prior research has documented meaningful differences between school performance of immigrant and native students. Multicultural education has been associated with academic failure of foreign students. e aim of this study was to examine the impact of a set of psychosocial variables on the perceived academic achievement of first generation immigrant adolescents from public secondary schools in Northern Spain. Results showed that 46% of the variability in foreign students’ perceived academic performance was explained by home-school cultural dissonance. We also explored the impact of acculturation orientation to separation, perception of discrimination from teachers, school adjustment, and psychological well-being in academic performance. Any multicultural education context should take into account psychosocial adjustment, given its influence on academic performance of all studentsSe han hallado diferencias significativas entre el rendimiento académico de los inmigrantes y el de los estudiantes nativos. Sin embargo, hay una escasa evidencia acerca de los aspectos psicosociales de este fenómeno. El objetivo de este estudio fue examinar el impacto de un conjunto de variables psicosociales: disonancia cultural y orientaciones de aculturación en el rendimiento académico percibido de adolescentes inmigrantes de primera generación de centros de Educación Secundaria en el Norte de España. Los resultados mostraron que alrededor del 46% de la variabilidad en el rendimiento era explicada por la disonancia cultural entre escuela y hogar. Cualquier contexto de educación multicultural ha de tomar en consideración el ajuste psicosocial, dada su influencia en el rendimiento académico de los estudiantes.http://www.redalyc.org/jatsRepo/647/64753989003/index.htm

Taxonomic review and evolutionary trends of Levipustulini and Absenticostini (Brachiopoda) from Argentina : palaeobiogeographic and palaeoclimatic implications

The diagnosis and composition of the brachiopod Tribe Levipustulini Lazarev, 1985 is reviewed, leading to a detailed revision of the genera Levipustula Maxwell, 1951 and Lanipustula Klets, 1983, as well as a review of previous records of the species Levipustula levis Maxwell from Australia and Argentina. The presence of Lanipustula patagoniensis Simanauskas in Patagonia is confirmed with additional topotypic material described and illustrated. Based on this review, we reassign Levipustula levis from New South Wales, Australia to Lanipustula. Two new species, Lanipustula kletsi from the middle Pennsylvanian of Patagonia and the Absenticostinin Absenticosta bruntoneileenae from the latest Viséan of western Argentina, are proposed. Abstenticosta bruntoneileenae is suggested as a possible ancestral stock of the Patagonian Levipustulini through the lineage Lanipustula-Verchojania-Jakutoproductus-Piatnitzkya (Serpukhovian-middle Artinskian). The development of similar phylogenetic lineages of Levipustulini in high latitude regions of both northern and southern hemispheres (such as Siberia in Northeast Asia and Patagonia in southwestern Gondwana) is here interpreted as a consequence of parallel evolution. The progressive palaeobiogeographic isolation of Patagonia from mainland South America, coupled with its southward drift under cold palaeoclimatic conditions during middle Carboniferous-earliest Permian times, is proposed to have triggered the Levipustulini vicariance

Micromorfological and mineralogical transformations in the weathering process of the Viveiro and Traba Granodiorites

[Resumen] Se realiza el estudio de dos perfiles de meteorizaci6n sobre granodioritas en Galicia (NW de España). El grado de drenaje condiciona la evolución de los feldespatos: en la saprolita de grano más grueso, con grandes fisuras, se transforman en gibbsita, en la de grano más fino este mineral aparece en las primeras etapas pero el producto final es halloysita. Las micas evolucionan en ambos casos hacia vermiculitas hidroxialumínicas.[Abstract] Two weathering profiles developed from granodiorites in Galicia (NW of Spain) are studied. The drainage degree determines the feldspars evolution. In the coarse grain saprolite, with great fissures, feldspars are transformed into gibbsite, while in the finer grain saprolite, the weathering product is halloysite. Micas change gradually to hidroxy-Al-interlayered vermiculite

Granite paleoweathering: A case-study under the tertiary deposit of Xinzo de Limia

[Resumen] Se estudia una paleoalteración desarrollada sobre granito y situada bajo un espesor de 120 m. de sedimentos en la cuenca terciaria de Xinzo de Limia (Ourense). El cambio minera16gico más significativo es la transformaci6n de las plagioclasas en caolinita. Se detectan también pequeñas proporciones de esmectitas. El estudio geoquímico revela una clara lixiviaci6n de bases, como lo pone de manifiesto la disminución de todos los índices de alteración (Indices de Parker, Reiche y pH de abrasi6n). El proceso de meteorización dominante es la monosialitización, con una cierta tendencia bisialítica en las primeras fases de la alteración.[Abstract] A granite paleoweathering located under 120 m of tertiary sediments at Xinzo de Limia (Galicia, NW Spain) is studied. The transformation ofplagioclase in kaolinite is the most important mineralogical change ocurred during the process. Minor proportions of smectite- are detected too. The geochemistry study reveales an evident lixiviation of bases, so the different weathering rates decrease as the process progresses (Parker and Reiche indexes and abrasion-pH). The dominant process of weathering is the monosialitization (PEDRO, 1979) although the first phases show a bisialitic trend

Automatic tracking and deformation measurements of red blood cells flowing through a microchannel with a microstenosis: the keyhole model

This study aimed to assess the motion and its deformation index (DI) of red blood cells (RBCs) flowing through a microchannel with a microstenosis using an image analysis-based method. For this purpose, a microchannel having a smooth contraction was used and the images were captured by a standard high-speed microscopy system. An automatic image-processing and analysing method was developed in a MATLAB environment to not only track the motion of RBCs but also measure the DI along the microchannel. The keyhole model, tested in this study, proved to be a promising technique to automatically track individual RBCs in microchannels.This study was financially supported by the Science and Technology Foundation (FCT), COMPETE, QREN and the European Union (FEDER) [grant numbers PTDC/SAU-BEB/ 105650/2008, PTDC/SAU-ENB/116929/2010, EXPL/EMS-SIS/ 2215/2013]info:eu-repo/semantics/publishedVersio

Weathering in granite and lamprophyre contact

[Resumen] Se realiza el estudio microestructural, mineralógico y geoquímico del proceso de meteorización en una zona de contacto granito-lamprófido. En la roca granítica se observa gibbsita, en los medios muy lixiviados, y filosilicatos 1: 1 en los menos drenados. En ellamprófido los productos son filosilicatos 1: 1, integrados vermiculíticos y oxi-hidróxidos de hierro; la abundancia de estos óxidos permite la conservación de la estructura original hasta etapas muy avanzadas dé la meteorización. El proceso global es de tipo monosialítico (fermonosialítico en las rocas básicas) con una tendencia inicial alitizante en las rocas graníticas. El pH de abrasión constituye un buen índice del grado de meteorización de estas rocas.[Abstract] In this paper is developed a microstructural, mineralogical and geochemical study of the weathering process in a contact between a granitic rock and a lamprophyre. In the granitic rack the main weathering products are gibbsite, under strongly leaching conditions, and 1: 1 phyllosilicates when the drainage is lesser. In the lamprophyre the products are 1: 1 phyllosilicates, vermiculitic integrades and iron oxides; the abundance of this oxides permit the conservation of rock structure till advanced stages of weathering. The overall process is moniosiallitic (fermonosiallitic in the basic rock), although an allitic tendency can be appreciated during the initial stages of the granitic rock weathering. The abrasion pH is good index to asses the weathering degree of these rocks

Yagonia Roberts (brachiopoda : chonetidina) from the malimán formation, lower carboniferous of western Argentina : palaeobiogeographical implications

A new anoplid chonetid species, Yagonia furquei sp. nov., is described from the Lower Carboniferous (late Tournaisian–early Viséan) Malimán Formation of western Argentina. The associated temperate ‘Malimanian’ fauna is suggested to indicate an initial biotic segregation that took place in western Gondwana (southwestern South America), a palaeobiogeographic event that predated the late Viséan global cooling and associated major palaeolatitudinal biotic differentiation. Occurrences of Yagonia are here interpreted as evidence of a ‘south to north’ faunal migration pathway, here named the Austropanthalassic–Rheic oceanic corridor, established in western Gondwana during the late Early Carboniferous

Phyllosilicate crystallinity in soils and weathering products from granitic rocks of Galicia

[Resumen] Se ha determinado la cristalinidad de micas y filosilicatos 1: 1 dioctaédricos de los limos y arcillas de 20 perfiles edáficos desarrollados sobre rocas graníticas. Se observa una estrecha relación entre el valor del índice de cristalinidad de los filosilicatos 2: 1, el tipo de mica predominante en el material de partida y el grado de desarrollo de los suelos; la menor cristalinidad aparece asociada a suelos formados a partir de materiales en los que la biotita es la única mica presente o la predominante. Los estudios de D. R. X., A. T. D. e 1. R. coinciden en señalar el predominio de filosicitatos 1: 1 de muy débil organización interna, comprobándose por microscopía electrónica que son fundamentalmente de tipo halloysítico[Abstract] Micas and dioctaedric 1: 1 phyllosilicate crystallinity of loam and clay fractions of twenty soil profiles developed from granite rocks have been determined. There are a clear relation among the cystallinity index of 2: 1 phyllosilicate, the prevailing type of mica in the soil-parent material and the soil evolution degree. Cystallinity is the lowest when soils are formed from granitic material when the most abundant mica is the biotite. XRD, DTA and RI studies indicate the predominance of very low ordered 1: 1 phyllosilicates, electron microscopy shows that they are mainly halloysitic anes