Igneous differentiation in porphyry dikes

[Resumen] Se aborda de manera teórica los principales procesos operativos de diferenciación ígnea en secciones transversales de los conductos filonianos, aplicándolo a los diques de pórfido granítico s. 1. del Sistema Central Español. Para estos magmas se deduce un régimen de flujo marcadamente laminar en el conducto (:~ 30 mts. potencia). Estos caracteres impiden tanto la efectividad de franccionamiento cristalino «in situ:\), como grados importantes de asimilación o contaminación en ruta hacia la superficie. Los diques simples, de flujos isoviscosos, van a diferenciarse por fenómenos, principalmente, de flujo ígneo, en ocasiones combinado con la presencia de varios magmas fluyendo a la vez en el mismo pulso (conductos gruesos o flujos veloces). Con estos mecanismos se tenderá a generar evoluciones del tipo félsico a máfico, de borde a centro del dique de pórfido. Los diques compuestos se formarán cuando los magmas son suficientemente contrastados en sus caracteres físicos (viscosidad, p. ej.) y químicos, o cuando son varíos pulsos magmáticos a través del mismo conducto. En estos casos podría haber fen6menos de mezcla magmática si la diferencia de viscosidad es alta y uno de esos magmas es poco viscoso (magmas básicos). En estos casos podrían generarse zonas básicas en el borde, o no, de los diques. de pórfido. En resumen la diferenciación de flujo, la mezcla magmática y la asociación de varios líquidos fluyendo en el mismo conducto (de manera simultánea o por pulsos magmáticos algo separados en el tiempo), parecen ser los mecanismos de diferenciación ígnea más efectivos de estos magmas graníticos que fluyen en angostos conductos filonianos[Abstract] We deal in theoretical way wíth the main differentiation proccesses taking place in dike conducts, applied to the porphyry dikes of the Spanish Central System. For these magmas we infer a strong laminar flow regime (~30 m dike witdh). This, prevent an efficient «in situ:\) cristal fractionation as well as large extent of assimilation-contamination processes during the ascent of the magmas «en route» to more surface levels. Simple dikes, with isoviscous flow, could differentiate mainley by igneous flow. Sometimes this mechanism is combinated with the possibility of severa! Magmas flowing togheter on the same pulse (thick dikes or fast flows). With these mechanisms felsic to mafic evolutions are favoured inward the porphyry dike. Composite dikes are formed when magmas are contrasted enough in their chemical or physical features (p. ej. viscosity), or when different magmatic pulses occur in the same channel. In these conditions commingling of magmas could exist if the viscosity ratio is high apd one of the magmas is very fluid (basic one). These processes could generate basic margins in the porphyry dikes. In short, flow differentiation, magmatic mixing and flowing of associated magmas (simultaneously or by successive pulses), seem to be the more efficient differentiation mechanisms for granitic magmas flowing in narrow dikes

Task demands modulate decision and eye movement responses in the chimeric face test: examining the right hemisphere processing account

A large and growing body of work, conducted in both brain-intact and brain-damaged populations, has used the free viewing chimeric face test as a measure of hemispheric dominance for the extraction of emotional information from faces. These studies generally show that normal right-handed individuals tend to perceive chimeric faces as more emotional if the emotional expression is presented on the half of the face to the viewer's left (“left hemiface”). However, the mechanisms underlying this lateralized bias remain unclear. Here, we examine the extent to which this bias is driven by right hemisphere processing advantages vs. default scanning biases in a unique way—by changing task demands. In particular, we compare the original task with one in which right-hemisphere-biased processing cannot provide a decision advantage. Our behavioral and eye movement data are inconsistent with the predictions of a default scanning bias account and support the idea that the left hemiface bias found in the chimeric face test is largely due to strategic use of right hemisphere processing mechanisms

Dynamics of supercoiled DNA with complex knots: Large-scale rearrangements and persistent multi-strand interlocking

Knots and supercoiling are both introduced in bacterial plasmids by catalytic processes involving DNA strand passages. While the effects on plasmid organization has been extensively studied for knotting and supercoiling taken separately, much less is known about their concurrent action. Here, we use molecular dynamics simulations and oxDNA, an accurate mesoscopic DNA model, to study the kinetic and metric changes introduced by complex (five-crossing) knots and supercoiling in 2 kbp-long DNA rings. We find several unexpected results. First, the conformational ensemble is dominated by two distinct states, differing in branchedness and knot size. Secondly, fluctuations between these states are as fast as the metric relaxation of unknotted rings. In spite of this, certain boundaries of knotted and plectonemically-wound regions can persist over much longer timescales. These pinned regions involve multiple strands that are interlocked by the cooperative action of topological and supercoiling constraints. Their long-lived character may be relevant for the simplifying action of topoisomerases

“PRESCRIPCIÓN DE METFORMINA EN PACIENTES ANCIANOS HOSPITALIZADOS CON CONTRAINDICACIÓN PARA LA MISMA, EN EL CENTRO MEDICO ISSEMyM DE ENERO DEL AÑO 2009 A ENERO DEL 2012”

El uso de metformina ha sido asociado con el desarrollo de acidosis láctica, la cual aumenta su incidencia ante la presencia de ciertos factores de riesgo, éstos son considerados como contraindicados para el uso de la metformina, sin embargo se ha descrito la prescripción inadecuada de la metformina frecuentemente en pacientes que tienen alguna de éstas contraindicaciones. Aunque la incidencia de ésta complicación es baja, tiene una alta tasa de mortalidad, por lo que al prescribir metformina debera individualizarse en cada paciente según las guías de recomendaciones y precauciones de este hipoglucemiante oral, sin embargo la presencia de múltiples comorbilidades en los ancianos como lo son Enfermedad pulmonar obstructiva Crónica, Insuficiencia Renal Crónica, Insuficiencia Cardiaca Congestiva, Insuficiencia arterial lo qué hace que el tratamiento farmacológico con hipoglucemiantes orales requiera la consideración de interacciones fármaco-enfermedad y fármaco-fármaco. Se han reportado hasta mayor a un 20% la prescripción inadecuada de metformina en este grupo de pacientes

Directional translocation resistance of Zika xrRNA

xrRNAs from flaviviruses survive in host cells because of their exceptional dichotomic response to the unfolding action of different enzymes. They can be unwound, and hence copied, by replicases, and yet can resist degradation by exonucleases. How the same stretch of xrRNA can encode such diverse responses is an open question. Here, by using atomistic models and translocation simulations, we uncover an elaborate and directional mechanism for how stress propagates when the two xrRNA ends, 5 \u2032 and 3 \u2032, are driven through a pore. Pulling the 3 \u2032 end, as done by replicases, elicits a progressive unfolding; pulling the 5 \u2032 end, as done by exonucleases, triggers a counterintuitive molecular tightening. Thus, in what appears to be a remarkable instance of intra-molecular tensegrity, the very pulling of the 5 \u2032 end is what boosts resistance to translocation and consequently to degradation. The uncovered mechanistic principle might be co-opted to design molecular meta-materials

Neural Prediction of Communication-Relevant Outcomes

Understanding and predicting the mechanisms and consequences of effective communication may be greatly advanced by leveraging knowledge from social and cognitive neuroscience research. We build on prior brain research that mapped mental processes, and show that information gained from neuroimaging can predict variation in communication outcomes over and above that associated with self-report. We further discuss how neural measures can complement physiological and other implicit measures. The brain-as-predictor approach can (1) allow researchers to predict individual and population level outcomes of exposure to communication stimuli with greater accuracy and (2) provide a better understanding of the mental processes underlying behaviors relevant to communication research. In this article, we give a detailed description of the brain-as-predictor approach and provide a guide for scholars interested in employing it in their research. We then discuss how the brain-as-predictor approach can be used to provide theoretical insights in communication research. Given its potential for advancing theory and practice, we argue that the brain-as-predictor approach can serve as a valuable addition to the communication science toolbox and provide a brief checklist for authors, reviewers and editors interested in using the approach

HYDROLOGICAL VARIABILITY IN WESTERN TROPICAL SOUTH AMERICA: CLIMATIC DRIVERS, MODEL SIMULATION, AND SUBSEASONAL FORECAST.

Western Tropical South America (WTSA) is a bioclimatic and topographic diverse region whose socio-economic development heavily depends on rainfall variability. Given this vulnerability, there is a significant need for more detailed studies of climate variability and predictability in this region. For this reason, this thesis aims to examine the possible drivers of subsesonal to subsesonal (S2S) rainfall variability in WTSA and to implement a modeling framework for an S2S hydrological prediction for the region. The thesis consists of four specific inquiries: (1) diagnostic investigation of atmospheric mechanisms associated with subsesonal precipitation variability; (2) development and implementation of a customized land surface model (Noah-MP) for hydrological simulation; (3) quantification of the sensitivity of hydrological simulations with the modeling system developed in (2), with a focus on vegetation parameterization; and (4) the development and evaluation of a hydrological sub-seasonal to seasonal hindcast system (S2S-HSF) which is based on (2) and (3). In the first investigation, we look specifically at the temporal and spatial evolution of Madden-Julian Oscillation (MJO) and the Rossby and Kelvin wave dynamics. We find that the migration of the MJO convective core is the main driver of rainfall variability across WTSA. In the second study we find that satellite-derived rainfall products offer reasonably reliable performance to support hydrological simulation, while hydrological simulation of runoff, soil moisture, and evapotranspiration vary across WTSA. In the third, we establish significant discrepancies in the representation of vegetation across different input datasets and parameterizations. Yet, simulated hydrological surface fluxes across are not significantly impacted by the representation of the vegetation on the model. Finally, in the fourth, we observe that S2S-HSF has a good skill performance for up to one month for meteorological fields, with longer skill horizons for hydrological variables such as soil moisture and evapotranspiration that benefit from persistent influence of initial conditions alongside meteorological forecasts. The work in this dissertation provides better understanding of tropical modes of seasonal-to-seasonal predictability and contributes to S2S hydrological systems that can aid in future development of operational hydrological S2S models for rainfall, evapotranspiration, and runoff to support early warnings systems in WTSA