Desequilibrios nominales y reales del tipo de cambio en Colombia

La estimación de los desequilibrios nominales y reales del tipo de cambio(TC) en Colombia se construye a partir de dos componentes: el permanenteasociado con una tendencia estocástica (no estacionaria) y el transitoriovinculado con el ciclo (estacionario). La separación entre lo permanente ylo transitorio se realiza a partir de las relaciones de largo plazo entre el TCnominal (real) y sus determinantes fundamentales. El nivel de equilibrio dela TC nominal (real) se obtiene como el componente permanente, según lametodología de common trends", aplicada a la TC nominal y a susdeterminantes fundamentales, mientras que el componente transitorio secalcula por residuo y se asocia al desequilibrio. El ejercicio se lleva a cabopara diferentes frecuencias (anual y trimestral) y períodos de información y se usan variosmodelos de determinación del TC nominal y real."tasa de cambio real, equilibrio de la tasa de cambio real.

Studying DNA Double-Strand Break Repair: An Ever-Growing Toolbox

To ward off against the catastrophic consequences of persistent DNA double-strand breaks (DSBs), eukaryotic cells have developed a set of complex signaling networks that detect these DNA lesions, orchestrate cell cycle checkpoints and ultimately lead to their repair. Collectively, these signaling networks comprise the DNA damage response (DDR). The current knowledge of the molecular determinants and mechanistic details of the DDR owes greatly to the continuous development of ground-breaking experimental tools that couple the controlled induction of DSBs at distinct genomic positions with assays and reporters to investigate DNA repair pathways, their impact on other DNA-templated processes and the specific contribution of the chromatin environment. In this review, we present these tools, discuss their pros and cons and illustrate their contribution to our current understanding of the DDR.European Research Council (ERC-2014-CoG 647344

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

Wave energy in Europe: Views on experiences and progress to date

publisher: Elsevier articletitle: Wave energy in Europe: Views on experiences and progress to date journaltitle: International Journal of Marine Energy articlelink: http://dx.doi.org/10.1016/j.ijome.2015.09.001 content_type: article copyright: © 2015 Elsevier Ltd. All rights reserved

The high mass end of the stellar mass function: Dependence on stellar population models and agreement between fits to the light profile

We quantify the systematic effects on the stellar mass function which arise from assumptions about the stellar population, as well as how one fits the light profiles of the most luminous galaxies at z ~ 0.1. When comparing results from the literature, we are careful to separate out these effects. Our analysis shows that while systematics in the estimated comoving number density which arise from different treatments of the stellar population remain of order < 0.5 dex, systematics in photometry are now about 0.1 dex, despite recent claims in the literature. Compared to these more recent analyses, previous work based on Sloan Digital Sky Survey (SDSS) pipeline photometry leads to underestimates of rho_*(> M_*) by factors of 3-10 in the mass range 10^11 - 10^11.6 M_Sun, but up to a factor of 100 at higher stellar masses. This impacts studies which match massive galaxies to dark matter halos. Although systematics which arise from different treatments of the stellar population remain of order < 0.5 dex, our finding that systematics in photometry now amount to only about 0.1 dex in the stellar mass density is a significant improvement with respect to a decade ago. Our results highlight the importance of using the same stellar population and photometric models whenever low and high redshift samples are compared.Comment: 18 pages, 17 figures, accepted for publication in MNRAS. The PyMorph luminosities and stellar masses are available at https://www.physics.upenn.edu/~ameert/SDSS_PhotDec

FEM based mathematical modelling of thrust force during drilling of Al7075-T6

Like most machining processes, drilling is affected by many parameters such as the tool diameter, the cutting speed and feed. The current research investigates the possibility of developing a finite element modelling based prediction model for the generated thrust force during drilling of Al7075-T6 with solid carbide tools. A total of 27 drilling experiments were carried out in order to examine the interaction between three key parameters and their effect on thrust force. In addition, simulations of the experiments were realized with the use of DEFORM3D((TM))software in order to obtain the necessary numerical data. Finally, a comparison was made between the experimental and the numerical results to verify that reliable modelling is feasible. The mathematical model was acquired with the use of response surface methodology and the verification of the adequacy of the model was performed through an analysis of variance. The majority of the simulations yielded results in agreement with the experimental results at around 95% and the derived model offered an accuracy of 5.9%

CAD-Based Automated Design of FEA-Ready Cutting Tools

The resources of modern Finite Element Analysis (FEA) software provide engineers with powerful mechanisms that can be used to investigate numerous machining processes with satisfying results. Nevertheless, the success of a simulation, especially in three dimensions, relies heavily on the accuracy of the cutting tool models that are implemented in the analyses. With this in mind, the present paper presents an application developed via Computer-Aided Design (CAD) programming that enables the automated design of accurate cutting tool models that can be used in 3D turning simulations. The presented application was developed with the aid of the programming resources of a commercially available CAD system. Moreover, the parametric design methodology was employed in order to design the tools according to the appropriate standards. Concluding, a sample tool model was tested by performing a number of machining simulations based on typical cutting parameters. The yielded results were then compared to experimental values of the generated machining force components for validation. The findings of the study prove the functionality of the tool models since a high level of agreement occurred between the acquired numerical results and the experimental ones

Influence of the Nose Radius on the Machining Forces Induced during AISI-4140 Hard Turning: A CAD-Based and 3D FEM Approach

The present study investigated the performance of three ceramic inserts in terms of the micro-geometry (nose radius and cutting edge type) with the aid of a 3D finite element (FE) model. A set of nine simulation runs was performed according to three levels of cutting speed and feed rate with respect to a predefined depth of cut and tool nose radius. The yielded results were compared to the experimental values that were acquired at identical cutting conditions as the simulated ones for verification purposes. Consequently, two more sets of nine simulations each were carried out so that a total of 27 turning simulation runs would adduce. The two extra sets corresponded to the same cutting conditions, but to different cutting tools (with varied nose radius). Moreover, a prediction model was established based on statistical methodologies such as the response surface methodology (RSM) and the analysis of variance (ANOVA), further investigating the relationship between the critical parameters (cutting speed, feed rate, and nose radius) and their influence on the generated turning force components. The comparison between the experimental values of the cutting force components and the simulated ones demonstrated an increased correlation that exceeded 89%. Similarly, the values derived from the statistical model were in compliance with the equivalent FE model values due to the verified adequacy

Engineering applications using CAD based application programming interface

Automating the design process of a product or a system can provide engineers and designers with many benefits. As such, repeatable tasks that are time consuming can be handled automatically and with minimal human attention. This is achieved by using the API (Application Programmable Interface) of CAD systems in order to create macros or even develop software applications. The present paper deals with an application that has been developed with the API of a general purposes CAD system. This application automates the design process of a standard pneumatic double acting cylinder based on the appropriate inserted parameters (ISO 15552).The design process begins with the creation of a series of components developed as solids, and extends to the extraction of basic attributes and properties from the complete mechanical assembly. Finally, the assembled models and the extracted data can be used to further study the design of the pneumatic double acting cylinder. It is expected in the future to expand the features of the presented application in order to automate the design process of other related mechanical systems