How tight should one's hands be tied? Fear of floating and credibility of exchange rate regimes

This paper analyzes the linkages between the credibility of a target zone regime, the volatility of the exchange rate, and the width of the band where the exchange rate is allowed to fluctuate. These three concepts should be related since the band width induces a trade-off between credibility and volatility. Narrower bands should give less scope for the exchange rate to fluctuate but may make agents perceive a larger probability of realignment which by itself should increase the volatility of the exchange rate. We build a model where this trade-off is made explicit. The model is used to understand the reduction in volatility experienced by most EMS countries after their target zones were widened on August 1993. As a natural extension, the model also rationalizes the existence of non-official, implicit target zones (or fear of floating), suggested by some authors.fear of floating, target zones, exchange rate arrangements, rational expectations, credibility

Credit Markets and the Propagation of Monetary Policy Shocks

This paper analyzes the propagation of monetary policy shocks through the creation of credit in an economy. Models of the monetary transmission mechanism typically feature responses which last for a few quarters contrary to what the empirical evidence suggests. To propagate the impact of monetary shocks over time, these models introduce adjustment costs by which agents find it optimal to change their decisions slowly. This paper presents another explanation that does not rely on any sort of adjustment costs or stickiness. In our economy, agents own assets and make occupational choices. Banks intermediate between agents demanding and supplying assets. Our interpretation is based on the way banks create credit and how the monetary authority affects the process of financial intermediation through its monetary policy. As the central bank lowers the interest rate by buying government bonds in exchange for reserves, high productive entrepreneurs are able to borrow more resources from low productivity agents. We show that this movement of capital among agents sets in motion a response of the economy that resembles an expansionary phase of the cycle.Credit, Monetary policy shock; Heterogeneous agents

Free boundary extension of the SIESTA code and its application to the Wendelstein 7-X

The race for obtaining new sources of clean energy is going in many directions. One of them, which is being studied since the 1950’s, is nuclear fusion. Nuclear fusion, which consists on joining two light atoms, occurs naturally at the core of stars. The process is driven by the high pressure at the core due to gravitational effects. The high pressure increases the energy of the atoms in the core to the point of them having enough energy to overcome the electrostatic repulsion when colliding. In this process an impressive amount of energy is liberated which, as with nuclear fission, can be transformed to electrical energy. Clearly the conditions met in the core of stars is not fulfilled on the surface of Earth. Nevertheless there are methods for reproducing conditions on Earth under which fusion is possible, the most promising one being the construction of a magnetic trap containing gas which is then heated up to temperatures high enough for attaining fusion. Due to the high temperatures the gas is converted to plasma which means that it can be contained using electromagnetic fields. Nevertheless it is difficult to contain the highly energetic particles and complex designs of magnetic traps are required. The two main designs being explored nowadays are called the tokamak and the stellarator, both have a toroidal geometry but different operational properties. Plasma dynamics in magnetic confinement devices is a very complex topic to study, mainly because turbulent processes are involved, but also because the interaction between the charged particles, the fields their movements create and the external electromagnetic fields is a system for which the solution to the dynamics equations is hard to obtain. Any deviation from the expected behaviour can result in a considerable alteration of the electromagnetic fields which may cause important deviations of the magnetic configuration from the designed one, preventing fusion to take place and torpedoing the confinement properties of the devices. This is why the study of plasma dynamics is extremely important. In order to understand the dynamics of magnetically confined plasmas it is necessary to have reliable tools which can properly describe confined plasmas, taking into account the possible interactions they may go through at laboratory conditions in fusion devices. The ideal magnetohydrodynamic (MHD) theory is capable of describing the global behaviour of fusion plasmas, therefore it is broadly used for the computation of magnetic equilibria in fusion devices. Other theories, which consider the particle movement of the ions and electrons inside of plasmas, are used whenever a more detailed solution is needed, for example in the study of energy transport properties in fusion plasmas. The equations constituting the ideal MHD theory are also hard to solve, therefore numerical codes which do the work of finding solutions are needed. These codes are of utmost importance to analyse equilibria of different experiments. The well known VMEC code (Variational Moments Equilibrium Code) does the three-dimensional ideal MHD analysis assuming nested magnetic surfaces, i.e. a layered set of torii. VMEC is broadly used in the fusion community in the analysis of the MHD equilibria. It is so broadly used that many codes rely on its equilibria solutions to run further simulations. SIESTA (Scalable Iterative Equilibrium Solver for Toroidal Applications) is one of such codes that rely on VMEC, taking a step further on the equilibrium solution. Using VMEC’s solution, SIESTA computes the ideal MHD equilibrium solution of the problem under study, without the assumption of nested magnetic surfaces. This results in the possible development of magnetic islands and stochastic regions. These type of structures are important in the study of magnetically confined plasmas because they can greatly damage the confinement properties of fusion devices. Although in some cases, as is the case of the Wendelstein 7-X (W7-X) stellarator, island structures can be used as part of the design of the experiment. In the case of the W7-X , a chain of magnetic islands help the correct functioning of the plasma divertor, which are plates taking up high energy fluxes coming out of the confined plasma region. In this special case, a modification on the magnetic island structure could lead to energy deposition on the plasma vessel, which may undermine the operation of the device. The divertor island structure in the W7-X is located just outside the last closed flux surface (LCFS), this being outside of VMEC’s computational domain because outside this limit it is not able to find a solution for a closed (nested) magnetic surface. SIESTA, as was originally conceived, has the limiting aspect that it solves the equilibrium inside of the LCFS found by VMEC without modifying this boundary. This condition implies that the results obtained for equilibria where there are possible instabilities or perturbations close to the LCFS are not well computed since SIESTA leaves the LCFS untouched. In this work a free-plasma-boundary version of SIESTA is developed in order to overcome this original limitation. The approach used consists on extending the analysis domain given by VMEC, in such a way that the vacuum region, or at least the most important part of it, is contained within the analysis volume of SIESTA. This requires the extension of the numerical analysis mesh guaranteeing the continuity of the metric elements on the mesh, a good approximation of the magnetic field solution in all the volume and a pressure solution which couples with the magnetic field. These three requirements have been solved and the extended version of SIESTA has been implemented. The field has been computed using the vector magnetic potential, which ensures the continuity of the magnetic field solution. The new version of SIESTA is applied to the specific case of the Wendelstein 7-X stellarator, at the IPP Greifswald (Germany), making comparisons with previous studies of equilibria showing the development of neoclassical bootstrap currents which cause the divertor island chain to shift its position. The previous studies were carried out with the VMEC-EXTENDER code combination, which is the general tool for ideal MHD equilibrium studies used in IPP. This code combination takes into account the equilibrium solution of VMEC to compute a magnetic field created by plasma currents by use of the virtual casing principle (VCP). The solution is then complemented by the vacuum field calculation derived from a Biot-Savart integrator code. Because of the combination of different solutions coming from different codes, the method is not fully consistent. Nevertheless, it has shown to be correct for the vacuum case and has been tested to be close to the experiment. This lack of consistency is avoided in the new version of SIESTA

Estudio de impacto del tratado de libre comercio en la ciudad de Pereira en los sectores estratégicos fabricación de prendas de vestir y operadores turísticos

En la búsqueda de políticas que permitan incrementar los niveles de competitividad de Pereira, la Alcaldía de la ciudad, en alianza con el sector educativo, en particular con la Universidad Tecnológica de Pereira y la Universidad Colegio Mayor de Nuestra Señora del Rosario, realiza el proyecto titulado “Estudio de impacto del tratado de libre comercio en la ciudad de Pereira en el sector estratégico fabricación de prendas de vestir”. El análisis sectorial presentado se desarrolló utilizando como base la propuesta metodológica de análisis sectorial desarrollada por el Grupo de Investigación en Perdurabilidad Empresarial de la Facultad de Administración de la Universidad del Rosario. Su estudio se fundamenta en el empleo de lo que se ha denominado “la nueva microeconomía de la firma”, en la que la comprensión de la estrategia de los sectores estratégicos se constituye en elemento de primer nivel para la toma de decisiones que afecten su comportamiento y les permitan lograr la perdurabilidad con crecimiento rentable. Por lo general, al hacer un análisis sectorial se recurre a cifras macroeconómicas con las cuales los diferentes actores, como el Gobierno, los gremios y los empresarios establecen directrices y se preparan para negociaciones comerciales con otros países y/o regiones. Sin embargo, surge una pregunta: ¿conocemos realmente los sectores económicos? Muchos no dudarían un segundo y dirían que sí, pero el conocimiento se hace insuficiente si se soporta únicamente en cifras económicas como el producto interno bruto (PIB), la inflación, el nivel de exportaciones, la tasa de desempleo, la devaluación, el índice de precios al productor, entre otras. Aun cuando la información económica es importante y necesaria para tomar decisiones, el análisis estructural es diferente por la construcción de pruebas a partir de la información estratégica. El modelo no descarta la información macroeconómica; es más, en su primera etapa se requiere contar con ella para contextualizar la industria, pero se enfoca en la estrategia como elemento que le permitirá a las empresas hacer frente a situaciones como los tratados de libre comercio con otros países. ¿Qué tan preparados se encuentran los sectores económicos de la ciudad de Pereira, en especial el de fabricación de prendas de vestir y el de operadores turísticos frente al TLC? ¿Cuál es el grado de hacinamiento que los sectores presentan? ¿Cuál es el crecimiento interno y externo presente en los sectores estratégicos en los últimos cuatro años? ¿Qué escenarios pueden esperar los sectores objeto de estudio frente al tratado de libre comercio con Estados Unidos de Norteamérica? Estos y otros interrogantes son abordados en el presente documento, resultado de la investigación realizada por la Universidad del Rosario. La estructura del documento es la siguiente: en primer lugar se hacen unas consideraciones generales sobre la metodología utilizada en el proyecto; a continuación se presenta el estudio para el sector fabricación de prendas de vestir, desarrollando cada una de las pruebas mencionadas en las consideraciones generales; por último, se incluyen algunas conclusiones del estudio, en las que se resalta que la integración entre el sector público y la academia permite avanzar en la consolidación de una ciudad más competitiva

Éxito, fracaso y entrepreneurship

¿Por qué razón unas empresas mueren mientras otras tienen éxito?, ¿qué debe hacerse para que las empresas que comienzan no desaparezcan tan rápidamente?, ¿cuáles son las condiciones que determinan el éxito empresarial? Estas son algunas de las preguntas que se hacen los académicos, gerentes y estudiantes de Administración de manera permanente. Para dar un aporte a la academia de la administración y poder construir respuestas coherentes, se elabora este documento, en el cual se hace una revisión de literatura del concepto de éxito y fracaso de las empresas, haciendo énfasis en el estudio de la responsabilidad del entrepreneur en el éxito o fracaso de las empresas. El texto se encuentra organizado de la siguiente manera: La primera sección contiene una descripción de la estrategia de búsqueda de la literatura utilizada; el lector podrá encontrar los pasos realizados para la elaboración del documento; la segunda sección muestra antecedentes sobre la manera como la literatura gerencial ha abordado el tema de éxito y fracaso empresarial; dividiendo en tres tipos de publicaciones, unas enfocadas sólo a mirar el éxito, son básicamente libros; una segunda categoría contiene artículos de journals y hace referencia a la muerte de las empresas; una tercera categoría incluye estudios comparativos entre empresas exitosas y empresas que han fracasado. Finaliza esta sección con la presentación de algunas defi niciones de éxito y fracaso ubicadas en la literatura. En la segunda sección, se identifi can los factores que inciden en que una empresa sea exitosa o fracase, entre ellos se encuentran la disciplina, el enfoque, la agilidad, la educación, la necesidad de logro. El texto cierra con las conclusiones, aquí se señalan los vacíos encontrados en la literatura que pueden ser tenidos en cuenta para futuras investigaciones sobre éxito, fracaso y entrepreneurship

Familial autoimmune thyroid disease and PTPN-22

Aim Autoimmune thyroid disease (AITD) is a multifactorial disease with a genetic predisposition. The protein tyrosine phosphatase-22 (PTPN-22) gene is a powerful inhibitor of T-cell activation. The aim of this study was to compare messenger RNA (mRNA) PTPN22 expression between healthy persons and patients with hypothyroidism and with their affected relatives. Methods This was a cross-sectional, prospective and descriptive study. DNA was extracted from leukocytes (4,000-10,000 cells) using the Magna Pure LC 2.0 Instrument and MagNA Pure LC RNA Isolation Kit I (Roche, Germany). A real-time polymerase reaction (qPCR) was performed utilizing the primer sets specific for the PTPN-22 gene, and the succinate dehydrogenase complex, the subunit A, Flavoprotein (Fp) (SDHA) constitutive gene. All reactions were performed with the 7500 Fast Real Time PCR System (Applied Biosystems, Applera International, Inc. Cheshire, UK) employing the SYBR Advantage qPCR Premix Kit (Clontech, USA). Results Twenty five patients with AITD (hypothyroidism), all females (mean age 39.6 ± 11.8 years) and 23 control subjects (mean age 24.4 ± 4.2 years) were included in the study. There was no statistical difference between both groups in PTPN-22 mRNA expression (p = 0.125). Conclusion There is no clear difference in mRNA PTPN-22 expression. The ideal genes for a systematic screening for familial AITD are yet to be found.This work was partially funded by Ciprés Grupo Médico (CGM)

La placenta como órgano endocrino compartido y su acción en el embarazo normoevolutivo

La placenta es el órgano más especializado implicado en el embarazo, que gracias a su compleja estructura y con la ayuda del líquido amniótico ayuda al crecimiento y desarrollo del feto en formación, siendo los cambios presentados en ella factores de alto impacto en el desarrollo intrauterino fetal. Teniendo en cuenta su relevancia en el embarazo, la placenta ha sido estudiada como parte de la etiología de condiciones gestacionales severas como la preeclampsia y el retraso en el crecimiento intrauterino (RCIU), en los cuales se ha encontrado la relación de los procesos placentarios con su desarrollo.La placenta humana cumple desde funciones de trasporte de nutrientes, respiración, y eliminación de desechos, hasta la función endocrina que alberga los efectos más importantes para la evolución y manutención de un embarazo normal, siendo una falla en dichas funciones, el desencadenante de patologías como la preeclampsia y el retraso en el crecimiento intrauterino (RCIU). Se destacan por su importancia hormonas como la gonadotropina coriónica humana (hCG), el lactógeno placentario humano (hPL), las hormonas tiroideas y las esteroideas, destacándose en estas últimas los mecanismos que se conjugan para su producción. Cabe destacar que en cuanto a las funciones endocrinas, si bien la placenta produce algunas hormonas por sí sola, no es órgano completamente independiente e involucra varios ejes hipotalámicos maternos para poder funcionar de una manera correcta, producir lo que se necesita, y contribuir a que la gestación llegue a un feliz término

Trade costs, openness and productivity: market access at home and abroad

This paper discusses the channels between openness and productivity and trade hampering factors. The stylized facts from the heterogeneous firms literature suggests that firms face market entry costs for each new product they export and to each new export market. Transport costs, border costs and retail and wholesale distribution costs might add up to 170% of the export value, but formal import tariffs and duties are relatively unimportant. The results by the Observatory of European SMEs survey, which has firm-level data for the whole European Union confirm this result. Lack of knowledge on export markets and regulations in other countries are important trade barriers for European firms. From these outcomes it could be derived that EU trade policies should be directed to deep integration with other countries, preferably by implementing internal market policies for goods and services trade and foreign direct investment. These policies can deal with reducing regulations heterogeneity, non-tariff barriers and customs procedures. Providing public information on export markets (e.g. customers, contact, and distribution networks) could also be helpful, if well targeted

Genetics of Thyroid Disorders

Background: Thyroid diseases are the most common endocrine pathologies second to diabetes. They have been shown to have high genetic impact, and variants in any of the genes involved in the metabolism of thyroid hormones have marked influence on the development of these diseases. Aim: To identify the genes that have been most involved in the development of thyroid pathologies by reviewing the literature with recent relevant articles. Materials and methods: We performed a literature search on the NCBI (National Center for Biotechnology Information) databases, and that of the European Bioinformatics Institute (EMBL-EBI) using keywords related to the topic of interest). Results: Activation of oncogenes such as RAS, BRAF, RET/PTC and the overstimulation of the PI3K/AKT pathway plays an important role in thyroid tumorigenesis. SLC5A5, SLC26A4, TG, TPO, DUOX2, DUOXA2 are related to hypothyroidism. Risk factors for Graves’ disease are associated with the presence of HLA-DR3, CTLA4, PTPN22, CD40, IL2RA (CD25), FCRL3, and IL23R. FOXE1 can be associated to hypothyroidism and papillary thyroid cancer. Conclusions: Thyroid diseases are polygenetic, and while there are sufficient pathways affected by genetic changes, and there is, to our knowledge, no gene that has been found to be specifically causal, and the pathology has been the result of the interaction of many genetic variables such as polymorphisms or mutations