Dynamics of interplate domain in subduction zones: influence of rheological parameters and subducting plate age

The properties of the subduction interplate domain are likely to affect not only the seismogenic potential of the subduction area but also the overall subduction process, as it influences its viability. Numerical simulations are performed to model the long-term equilibrium state of the subduction interplate when the diving lithosphere interacts with both the overriding plate and the surrounding convective mantle. The thermomechanical model combines a non-Newtonian viscous rheology and a pseudo-brittle rheology. Rock strength here depends on depth, temperature and stress, for both oceanic crust and mantle rocks. I study the evolution through time of, on one hand, the brittle-ductile transition (BDT) depth, <i>z</i><sub>BDT</sub>, and, on the other hand, of the kinematic decoupling depth, <i>z</i><sub>dec</sub>, simulated along the subduction interplate. The results show that both a high friction and a low ductile strength at the asthenospheric wedge tip shallow <i>z</i><sub>BDT</sub>. The influence of the weak material activation energy is of second order but not negligible. <i>z</i><sub>BDT</sub> becomes dependent on the ductile strength increase with depth (activation volume) if the BDT occurs at the interplate decoupling depth. Regarding the interplate decoupling depth, it is shallowed (1) significantly if mantle viscosity at asthenospheric wedge tip is low, (2) if the difference in mantle and interplate activation energy is weak, and (3) if the activation volume is increased. Very low friction coefficients and/or low asthenospheric viscosities promote <i>z</i><sub>BDT</sub> = <i>z</i><sub>dec</sub>. I then present how the subducting lithosphere age affects the brittle-ductile transition depth and the kinematic decoupling depth in this model. Simulations show that a rheological model in which the respective activation energies of mantle and interplate material are too close hinders the mechanical decoupling at the down-dip extent of the interplate, and eventually jams the subduction process during incipient subduction of a young (20-Myr-old) and soft lithosphere under a thick upper plate. Finally, both the BDT depth and the decoupling depth are a function of the subducting plate age, but are not influenced in the same fashion: cool and old subducting plates deepen the BDT but shallow the interplate decoupling depth. Even if BDT and kinematic decoupling are intrinsically related to different mechanisms of deformation, this work shows that they are able to interact closely. Comparison between modelling results and observations suggests a minimum friction coefficient of 0.045 for the interplate plane, even 0.069 in some cases, to model realistic BDT depths. The modelled <i>z</i><sub>dec</sub> is a bit deeper than suggested by geophysical observations. Eventually, the better way to improve the adjustment to observations may rely on a moderate to strong asthenosphere viscosity reduction in the metasomatised mantle wedge

Estudo de idoneidade de diferentes linguaxes de programación na aprendizaxe en Programación do Grao de Enxeñaría Informática

[Resumo] A materia de Programación forma parte do módulo de formación básica do Grao en Informática, o obxectivo desta materia é ensinar ao alumno a crear modelos computacionais de problemas do mundo real, a realización desta labor faise empregando unha linguaxe de programación. A linguaxe de programación empregada na materia para ensinar os alumnos é un elemento fundamental e crítico, xa que dependendo das súas características vai ser máis doado ou complicado acadar as competencias para o alumno: detección de erros, escritura dos programas, entorno de desenvolvemento (IDE), ... Unha mostra disto é que se emprega a mesma linguaxe desde a creación da Facultade de Informática (FIC). Está non é un tarefa trivial debido a que non tódalas linguaxes están deseñadas seguindo o mesmo paradigma de programación, algunhas son case experimentais mentres outras son de uso case exclusivamente comercial, hai linguaxes que non teñen compilador “propio”, ... Neste traballo se presentan o resultado da análise de diferentes linguaxes que compren coas características necesarias, como se indicou anteriormente, para o seu uso na docencia da materia, valorando a súa idoneidade nas características máis importantes desde un punto de vista docente. As linguaxes que observouse que as cumprían foron: C/C++, C#, Python, Java, Ada, Go, Dart, Pascal, Fortran, Haskell, Scala, Nim, D e Kotlin

Small-scale convection in a plume-fed low-viscosity layer beneath a moving plate

Two-dimensional simulations using a thermomechanical model based on a finite-difference method on a staggered grid and a marker in cell method are performed to study the plume-lithosphere interaction beneath moving plates. The plate and the convective mantle are modelled as a homogeneous peridotite with a Newtonian temperature- and pressure-dependent viscosity. A constant velocity, ranging from 5 to 12.5 cm yr−1, is imposed at the top of the plate. Plumes are generated by imposing a thermal anomaly of 150 to 350 K on a 50 km wide domain at the base of the model (700 km depth); the plate atop this thermal anomaly is 40 Myr old. We analyse (1) the kinematics of the plume as it impacts the moving plate, (2) the dynamics of time-dependent small-scale convection (SSC) instabilities developing in the low-viscosity layer formed by spreading of hot plume material at the base of the lithosphere and (3) the resulting thermal rejuvenation of the lithosphere. The spreading of the plume material at the base of the lithosphere, characterized by the ratio between the maximum down- and upstream horizontal (dimensionless) velocities in the plume-fed sublithospheric layer, Peup/Pedown depends on the ratio between the maximum plume upwelling velocity and the plate velocity, Peplume/Peplate. For fast plate velocities and sluggish plumes (low Peplume/Peplate), plate motion drags most plume material and downstream flow is dominant. As Peplume/Peplate increases, an increasing part of the plume material flows upstream. SSC systematically develops in the plume-fed sublithospheric layer, downstream from the plume. Onset time of SSC decreases with the Rayleigh number. For vigorous plumes, it does not depend on plate velocity. For more sluggish plumes, however, variations in the plume spreading behaviour at the base of the lithosphere result in a decrease in the onset time of SSCs with increasing plate velocity. In any case, SSC results in uplift of the isotherm 1573 K by up to 20 km relative to its initial equilibrium depth at the impact poin

Aislamiento de cocaína y benzoilecgonina en muestras de orina por extracciones líquido-líquido y en fase sólida y confirmación por Cromatografía líquida de alta resolución (HPLC)

El consumo ilícito de cocaína se ha incrementado extraordinariamente en los últimos años, por lo que resulta indispensable el desarrollo de metodologías seguras, rápidas y eficientes para su detección. En este trabajo se desarrollo una técnica de HPLC de fase reversa con detector de UV para identificar y cuantificar a la cocaína y la benzoilecgonina, con resultados satisfactorios en los parámetros del control de calidad.Se realizó un estudio de recobrado para el aislamiento de la cocaína y la benzoilecgonina en orina con extracciones liquido liquido y en fase sólida con tres tipos de columnas comerciales (Bond Elut Certify, Extrelut 3 y Supelclean LC-18). Las fracciones obtenidas con la extracción líquido-líquido resultaron muy contaminados, con porcentajes de recobrados bajos (45% y 28% para la cocaína y la benzoilecgonina, respectivamente. En las extracciones en fase sólida para la cocaína resultaron muy eficientes las columnas Supelclean LC-18 (87-102 %) y Extrelut 3 (70-102 %), mientras que para el aislamiento de la benzoilecgonina resultaron más eficiente las columnas Extrelut 3 (86-101 %) y Supelclean LC-18 (73-89%). Las columnas Bond Elut Certify resultaron poco eficientes para el aislamiento de la cocaína (53-79%) y con un recobrado aún mas bajo para su metabolito (2-21% %)

Back-arc strain in subduction zones: Statistical observations versus numerical modeling

International audience1] Recent statistical analysis by Lallemand et al. (2008) of subduction zone parameters revealed that the back-arc deformation mode depends on the combination between the subducting (nu(sub)) and upper (nu(up)) plate velocities. No significant strain is recorded in the arc area if plate kinematics verifies nu(up) = 0.5 vsub - 2.3 (cm/a) in the HS3 reference frame. Arc spreading ( shortening) occurs if nu(up) is greater ( lower) than the preceding relationship. We test this statistical law with numerical models of subduction, by applying constant plate velocities far away from the subduction zone. The subducting lithosphere is free to deform at all depths. We quantify the force applied on the two converging plates to sustain constant surface velocities. The simulated rheology combined viscous (non-Newtonian) and brittle behaviors, and depends on water content. The influence of subduction rate vs is first studied for a fixed upper plate. After 950 km of convergence ( steady state slab pull), the transition from extensional to compressive stresses in the upper plate occurs for vs similar to 1.4 cm/a. The effect of upper plate velocity is then tested at constant subduction rate. Upper plate retreat ( advance) with respect to the trench increases extension ( compression) in the arc lithosphere and increases ( decreases) the subducting plate dip. Our modeling confirms the statistical kinematic relationship between vsub and nu(up) that describes the transition from extensional to compressive stresses in the arc lithosphere, even if the modeled law is shifted toward higher rates of upper plate retreat, using our set of physical parameters ( e. g., 100 km thick subducting oceanic plate) and short- term simulations. Our results make valid the choice of the HS3 reference frame for assessing plate velocity influence on arc tectonic regime. The subduction model suggests that friction along the interplate contact and the mantle Stokes reaction could be the two main forces competing against slab pull for upper mantle subductions. Besides, our simulations show that the arc deformation mode is strongly time dependent

Artificial Neural Networks Manipulation Server: Research on the Integration of Databases and Artificial Neural Networks

The final publication is available at Springer via http://dx.doi.org/10.1007/s005210200011This paper proposes a new whole and distributed integration approach between Artificial Neural Networks (ANNs) and Databases (DBs) taking into account the different stages of the former’s lifecycle (training, test and running). The integration architecture which has been developed consists of an ANN Manipulation Server (AMS) based on a client-server approach, which improves the ANNs’ manipulation and experimentation capabilities considerably, and also those of their training and test sets, together with their modular reuse among possibly remote applications. Moreover, the chances of integrating ANNs and DBs are analysed, proposing a new level of integration which improves the integration features considerably. This level has not been contemplated yet at full reach in any of the commercial or experimental tools analysed up to the present date. Finally, the application of the integration architecture which has been developed to the specific domain of Environmental Impact Assessments (EIAs) is studied. Thus, the versatility and efficacy of that architecture for developing ANNs is tested. The enormous complexity of the functioning of the patterns which rule the environment’s behaviour, and the great number of variables involved, make it the ideal domain for experimenting on the application of ANNs together with DBs

Antimicrobial activity of poly(ester urea) electrospun fibers loaded with bacteriophages

The capacity to load bacteriophages into electrospun nanofibers of two representative biocompatible polymers has been evaluated, paying special attention to the possibility of preserving their antibacterial activity. Specifically, the work involves the following steps: (a) Evaluation of the effect of the applied electrical field on the phage activity; (b) evaluation of the activity when a lyophilization process could be avoided by using water soluble polymers (e.g., poly(ethylene glycol); (c) evaluation of the activity when dissolution of the polymer requires an organic solvent and lyophilization is theoretically necessary. In this case, a poly(ester urea) (PEU) derived from the natural L-leucine amino acid has been considered. Adsorption of commercial bacteriophage preparations into calcium carbonate particles was demonstrated to be a promising methodology to avoid lyophilization and keep the initial bactericide activity at a maximum. Phagestaph and Fersis bacteriophage commercial preparations have been selected for this study due to their spPeer ReviewedPostprint (published version

Language Learning Guide Mobile Application

While traveling around the world, a lack of common language is often encountered. This can be a reason of not truly experiencing the country and the people that one is visiting. Thus, knowing even just a little of the local language will be a great advantage for any foreigner visiting or staying in another country. This project focuses on developing a mobile application that would aid any traveller or foreigner here in Malaysia in learning to converse in the local language for a better stay. This project also attempts to find the effective, efficient and interesting ways to learn a language. It is focused in providing the user the basic conversations that a foreigner will mostly/likely encounter while visiting or staying in Malaysia. The application is for foreigners who can speak English and is trying to learn Bahasa Malaysia. The android platform is chosen for the development of the application and coding with Java and Eclipse were used. The research and survey done resulted in the findings that using visual-audio sensory and interactive techniques will provide a more engaging and thus a more effective way of learning. With this implemented in the application, results of the user acceptance test showed that with the mobile application, an increase of the competency of the users’ Bahasa Malaysia speaking skills is observed