A Lagrangian Analysis of the Northern Hemisphere Subtropical Jet

This study presents a 5-yr climatology of 7-day back trajectories started from the Northern Hemisphere subtropical jet. These trajectories provide insight into the seasonally and regionally varying angular momentum and potential vorticity characteristics of the air parcels that end up in the subtropical jet. The trajectories reveal preferred pathways of the air parcels that reach the subtropical jet from the tropics and the extratropics and allow estimation of the tropical and extratropical forcing of the subtropical jet. The back trajectories were calculated 7 days back in time and started every 6 h from December 2005 to November 2010 using the Interim European Centre for Medium-Range Weather Forecasts (ECMWF) Re-Analysis (ERA-Interim) dataset as a basis. The trajectories were started from the 345-K isentrope in areas where the wind speed exceeded a seasonally varying threshold and where the wind shear was confined to upper levels. During winter, the South American continent, the Indian Ocean, and the Maritime Continent are preferred areas of ascent into the upper troposphere. From these areas, air parcels follow an anticyclonic pathway into the subtropical jet. During summer, the majority of air parcels ascend over the Himalayas and Southeast Asia. Angular momentum is overall well conserved for trajectories that reach the subtropical jet from the deep tropics. In winter and spring, the hemispheric-mean angular momentum loss amounts to approximately 6%; in summer, it amounts to approximately 18%; and in fall, it amounts to approximately 13%. This seasonal variability is confirmed using an independent potential vorticity–based method to estimate tropical and extratropical forcing of the subtropical jet.

Stair climbing - An insight and comparison between women with and without joint hypermobility: A descriptive study.

Generalized joint hypermobility (GJH) is a frequent entity in rheumatology with higher prevalence among women. It is associated with chronic widespread pain, joint dislocations, arthralgia, fibromyalgia and early osteoarthritis. Stair climbing is an important functional task and can induce symptoms in hypermobile persons. The aim of this study was to compare ground reaction forces (GRF) and muscle activity during stair climbing in women with and without GJH. A cross-sectional study of 67 women with normal mobility and 128 hypermobile women was performed. The hypermobile women were further divided into 56 symptomatic and 47 asymptomatic. GRFs were measured by force plates embedded in a six step staircase, as well as surface electromyography (EMG) of six leg muscles. Parameters derived from GRF and EMG were compared between groups using t-test and ANOVA. For GRF no significant differences were found. EMG showed lower activity for the quadriceps during ascent and lower activity for hamstrings and quadriceps during descent in hypermobile women. For symptomatic hypermobile women these differences were even more accentuated. The differences in EMG may point towards an altered movement pattern during stair climbing, aimed at avoiding high muscle activation. However, differences were small, since stair climbing seems to be not demanding.

Predictive modelling of mineral scaling, corrosion and the performance of solute geothermometers in a granitoid-hosted, enhanced geothermal system

Experience is lacking with mineral scaling and corrosion in enhanced geothermal systems (EGS) in which surface water is circulated through hydraulically stimulated crystalline rocks. As an aid in designing EGS projects we have conducted multicomponent reactive-transport simulations to predict the likely characteristics of scales and corrosion that may form when exploiting heat from granitoid reservoir rocks at ∼200 °C and 5 km depth. The specifications of an EGS project at Basel, Switzerland, are used to constrain the model. The main water–rock reactions in the reservoir during hydraulic stimulation and the subsequent doublet operation were identified in a separate paper (Alt-Epping et al., 2013b). Here we use the computed composition of the reservoir fluid to (1) predict mineral scaling in the injection and production wells, (2) evaluate methods of chemical geothermometry and (3) identify geochemical indicators of incipient corrosion. The envisaged heat extraction scheme ensures that even if the reservoir fluid is in equilibrium with quartz, cooling of the fluid will not induce saturation with respect to amorphous silica, thus eliminating the risk of silica scaling. However, the ascending fluid attains saturation with respect to crystalline aluminosilicates such as albite, microcline and chlorite, and possibly with respect to amorphous aluminosilicates. If no silica-bearing minerals precipitate upon ascent, reservoir temperatures can be predicted by classical formulations of silica geothermometry. In contrast, Na/K concentration ratios in the production fluid reflect steady-state conditions in the reservoir rather than albite–microcline equilibrium. Thus, even though igneous orthoclase is abundant in the reservoir and albite precipitates as a secondary phase, Na/K geothermometers fail to yield accurate temperatures. Anhydrite, which is present in fractures in the Basel reservoir, is predicted to dissolve during operation. This may lead to precipitation of pyrite and, at high exposure of anhydrite to the circulating fluid, of hematite scaling in the geothermal installation. In general, incipient corrosion of the casing can be detected at the production wellhead through an increase in H2(aq) and the enhanced precipitation of Fe-bearing aluminosilicates. The appearance of magnetite in scales indicates high corrosion rates.

Morphological Brain Changes after Climbing to Extreme Altitudes-A Prospective Cohort Study.

BACKGROUND Findings of cerebral cortical atrophy, white matter lesions and microhemorrhages have been reported in high-altitude climbers. The aim of this study was to evaluate structural cerebral changes in a large cohort of climbers after an ascent to extreme altitudes and to correlate these findings with the severity of hypoxia and neurological signs during the climb. METHODS Magnetic resonance imaging (MRI) studies were performed in 38 mountaineers before and after participating in a high altitude (7126m) climbing expedition. The imaging studies were assessed for occurrence of new WM hyperintensities and microhemorrhages. Changes of partial volume estimates of cerebrospinal fluid, grey matter, and white matter were evaluated by voxel-based morphometry. Arterial oxygen saturation and acute mountain sickness scores were recorded daily during the climb. RESULTS On post-expedition imaging no new white matter hyperintensities were observed. Compared to baseline testing, we observed a significant cerebrospinal fluid fraction increase (0.34% [95% CI 0.10-0.58], p = 0.006) and a white matter fraction reduction (-0.18% [95% CI -0.32--0.04], p = 0.012), whereas the grey matter fraction remained stable (0.16% [95% CI -0.46-0.13], p = 0.278). Post-expedition imaging revealed new microhemorrhages in 3 of 15 climbers reaching an altitude of over 7000m. Affected climbers had significantly lower oxygen saturation values but not higher acute mountain sickness scores than climbers without microhemorrhages. CONCLUSIONS A single sojourn to extreme altitudes is not associated with development of focal white matter hyperintensities and grey matter atrophy but leads to a decrease in brain white matter fraction. Microhemorrhages indicative of substantial blood-brain barrier disruption occur in a significant number of climbers attaining extreme altitudes.

Differentiating the Multipoint Expected Improvement for Optimal Batch Design

This work deals with parallel optimization of expensive objective functions which are modelled as sample realizations of Gaussian processes. The study is formalized as a Bayesian optimization problem, or continuous multi-armed bandit problem, where a batch of q > 0 arms is pulled in parallel at each iteration. Several algorithms have been developed for choosing batches by trading off exploitation and exploration. As of today, the maximum Expected Improvement (EI) and Upper Confidence Bound (UCB) selection rules appear as the most prominent approaches for batch selection. Here, we build upon recent work on the multipoint Expected Improvement criterion, for which an analytic expansion relying on Tallis’ formula was recently established. The computational burden of this selection rule being still an issue in application, we derive a closed-form expression for the gradient of the multipoint Expected Improvement, which aims at facilitating its maximization using gradient-based ascent algorithms. Substantial computational savings are shown in application. In addition, our algorithms are tested numerically and compared to state-of-the-art UCB-based batchsequential algorithms. Combining starting designs relying on UCB with gradient-based EI local optimization finally appears as a sound option for batch design in distributed Gaussian Process optimization.

Ciberdemocracia ¿Ciberoptimismo? Análisis de algunos límites de los usos de Internet para el gobierno electrónico

El ascenso de Internet ha dado lugar a numerosas propuestas de uso de la red para la participación política. En el siguiente artículo se analizan algunos supuestos de la llamada democracia electrónica. Asimismo, se hace hincapié en dos aspectos: en primer lugar, la disposición de los individuos a adquirir informaciones tanto como las posibilidades de que las mismas impliquen una profundización de la participación y una mejora de la democracia-; en segundo lugar, el riesgo -por ciertas modalidades propias de este tipo de comunicación- de reforzar la tendencia de concebir la política como gestión, como elección de quien cumple con más eficacia los servicios que se demandan.

Economía e ideología en el franquismo : tensiones entre utopía y pragmatismo 1945 -1970

El presente trabajo enfoca desde una perspectiva comparativa y analítica algunos aspectos de la economía y la sociedad españolas durante años especialmente interesantes de la dictadura franquista. Se efectúa una revisión de la ideología con la que el régimen pretendió encarar, a través de un proyecto autárquico, inicialmente muy marcado por el modelo fascista, el despegue económico de España y los virajes posteriores originados en las tensiones surgidas en el seno de la sociedad y de los paradigmas externos que marcaban el rumbo hacia una integración de bloques. Como fecha límite de este estudio se presentan los últimos años de la década del '60, puesto que parecen constituir el cierre de un ciclo. En cuestiones ideológico-políticas ese cierre estuvo signado por el ascenso del almirante Carrero Blanco a una posición clave y la sustitución de los viejos falangistas por un grupo más homogéneo de "tecnócratas" del capitalismo moderno. En materia económica también se completó entonces un período de crecimiento sin precedentes en la economía española que hacia 1973/74 entró en una meseta, parte de la crisis cíclica compartida por la economía mundial.

Ascenso social, consolidación y prestigio. El caso de los portugueses y sus redes sociofamiliares en el Buenos Aires tardocolonial

Este trabajo tiene como propósito analizar el comportamiento y las estrategias sociales de los portugueses más destacados dentro de la comunidad porteña de Buenos Aires colonial tardío. Para este análisis, debemos tener en cuenta el crecimiento que tuvo la ciudad desde mediados del siglo XVIII lo que se denota claramente en la expansión del comercio atlántico. Es durante ese período que Buenos Aires pierde rápidamente las características de los pueblos predominantemente rurales para adquirir, en forma definitiva, los rasgos de una ciudad.

La educación secundaria como una demanda social bajo el primer peronismo. Un estudio de caso : El Colegio Nacional Mixto de Morón (1949-1955)

El artículo analiza la fundación de un Colegio Nacional en el distrito de Morón en el año 1949 bajo los designios del llamado primer peronismo (1946-1955). Da cuenta de un conjunto de aspectos que van desde la cuestión política encarnada en la centralización del sistema de enseñanza y la cuestión social, es decir, la demanda por una democratización del nivel secundario junto con los límites y falencias del sistema en un contexto caracterizado por el ascenso de las clases medias urbanas y la politización de la educación

Chemical and isotopic compositions of sediments from DSDP Hole 21-204

The highly depleted intra-oceanic Tonga-Kermadec island arc forms an endmember of arc systems and a unique location in which to isolate the effects of the slab flux. High precision TIMS uranium, thorium, strontium, neodymium, and lead isotopes, along with complete major and trace element data, have been obtained on an extensive sample set comprising fifty-eight lavas along the arc as well as nineteen samples of the subducting sediments at DSDP site 204 just to the east of the Tonga-Kermadec trench. Ca/Ti and Al/Ti ratios extend from values appropriate to an N-MORB source in the southern Kermadecs to very high ratios in Tonga interpreted to reflect increasing degrees of depletion of the mantle wedge due to backarc basalt extraction. The isotope data emphasize the need for four components in the petrogenesis of the lavas: (1) the mantle wedge; (2) a component with elevated 207Pb/204Pb towards which the Kermadec and southern Tongan lavas extend; (3) a component characterised by high 206Pb/204Pb, Ta/Nd, and low 143Nd/144Nd observed only in the northernmost Tongan islands of Tafahi and Niuatoputapu; (4) a fluid component characterised by strong enrichments of Rb, Ba, U, K, Ph, and Sr, relative to Th, Zr, and the REE and producing large 238U excesses ((230Th/238U) = 0.8-0.5) in the more depleted lavas. The mantle wedge (Component 1) is isotopically similar to the source of the Lau BABB. Component 2 is average pelagic sediment on the downgoing Pacific plate as observed at DSDP sites 595/596 and in the upper sections of the sediment pile at DSDP site 204. Mass balance calculations indicate that less than 0.5% is recycled into the arc lavas; essentially all the subducted sediment is returned to the upper mantle (~0.03 km**3/yr). Exceptionally low concentrations of Ta and Nb relative to Th and the LREE requires that this sediment component is added as a partial melt which was in equilibrium with residual rutile or ilmenite. Component 3 is identified as volcaniclastics from the Louisville Ridge which comprise the lower 44 m of the sediment section intersected at DSDP site 204. These volcaniclastics are spatially restricted to the vicinity of the Louisville Ridge and provide a unique sediment tracer which can be used to show that it takes 4 Myr from the time of subduction to its first appearance in the arc lava signature. Component 4, the fluid contribution to the lava source is inferred to contribute ~1 ppm Rb, 10 ppm Ba, 0.02 ppm U, 600 ppm K, 0.2 ppm Ph, and 30 ppm Sr. It has 87Sr/86Sr = 0.7035 and 206Pb/204Pb = 18.5 and thus it is inferred to have been derived from dehydration of the subducting altered oceanic crust. U-Th isotope disequilibria reflect the time since fluid release from the subducting slab and a reference line through the lowest (230Th/232Th) lavas constrains this to be 30000-50000 yr. The U-Th and Th-Ra isotope systematics are decoupled, and it is suggested that Th-Ra isotope disequilibria record the time since partial melting and thus indicate rapid channelled magma ascent. Olivine gabbro xenoliths from Raoul are interpreted as cumulates to their host lavas with which they form zero age U-Th isochrons indicating that minimal time was spent in magma chambers. The subduction signature is not observed in lavas from the backarc island of Niuafo'ou. These were derived from partial melting of fertile peridotite at 130-160 km depth with melt rates around 0.0002 kg/m**3/yr.

Ascenso social, consolidación y prestigio. El caso de los portugueses y sus redes sociofamiliares en el Buenos Aires tardocolonial

Este trabajo tiene como propósito analizar el comportamiento y las estrategias sociales de los portugueses más destacados dentro de la comunidad porteña de Buenos Aires colonial tardío. Para este análisis, debemos tener en cuenta el crecimiento que tuvo la ciudad desde mediados del siglo XVIII lo que se denota claramente en la expansión del comercio atlántico. Es durante ese período que Buenos Aires pierde rápidamente las características de los pueblos predominantemente rurales para adquirir, en forma definitiva, los rasgos de una ciudad.

La educación secundaria como una demanda social bajo el primer peronismo. Un estudio de caso : El Colegio Nacional Mixto de Morón (1949-1955)

El artículo analiza la fundación de un Colegio Nacional en el distrito de Morón en el año 1949 bajo los designios del llamado primer peronismo (1946-1955). Da cuenta de un conjunto de aspectos que van desde la cuestión política encarnada en la centralización del sistema de enseñanza y la cuestión social, es decir, la demanda por una democratización del nivel secundario junto con los límites y falencias del sistema en un contexto caracterizado por el ascenso de las clases medias urbanas y la politización de la educación

Geochemistry and isotopic ratios of basalts obtained during R/V Akademik Nikolaj Strakhov cruise ANS25

Based on the investigation of samples recovered during Cruise 25 of the R/V ''Akademik Nikolai Strakhov'', the character of magmatism was determined in the flank parts of the rift zone at the 74°05'N and 73°50'N region, where the direction of the rift valley changes from the north-northwest in the Knipovich Ridge to the northeast-trending structures of the Mohns Ridge. It was shown that the tholeiitic magmas of this region shows all the geochemical characteristics of TOR-2, which is typical of the Mohns Ridge and most oceanic rift zones worldwide, and differ from the basalts of the Knipovich Ridge, which are assigned to a shallower type of tholeiitic magmatism (Na-TOR). The persistent depletion of the magmas in terms of lithophile element contents and radiogenic isotope ratios of Sr, Nd, and Pb reflects the conditions of their formation during the ascent of the depleted oceanic mantle, which has occurred without significant complications since the early stages of the formation of the Mohns Ridge.

La educación secundaria como una demanda social bajo el primer peronismo. Un estudio de caso : El Colegio Nacional Mixto de Morón (1949-1955)

El artículo analiza la fundación de un Colegio Nacional en el distrito de Morón en el año 1949 bajo los designios del llamado primer peronismo (1946-1955). Da cuenta de un conjunto de aspectos que van desde la cuestión política encarnada en la centralización del sistema de enseñanza y la cuestión social, es decir, la demanda por una democratización del nivel secundario junto con los límites y falencias del sistema en un contexto caracterizado por el ascenso de las clases medias urbanas y la politización de la educación