Trade balance constraints and optimal regulation

In this paper we develop a model to understand the interactions between optimal regulation and external credit constraints. If a big proportion of the regulated sector is owned by foreign investors, a credit-constrained country who wants to send profits abroad has to generate enough surplus in the trade account in order to compensate capital outflows. This may be a real problem in developing countries, in which regulated sectors are big and foreign ownership is very important. We show that the credit constraint translates into a constraint of maximum profits for the regulated firm. As a consequence, overall efficiency in the regulated sector is reduced to maintain incentive compatibility. With a flexible exchange rate, devaluation is an additional instrument to relax the credit constraint, but the country is not in general willing to relax it completely. Efficiency is higher than with a fixed exchange rate, but it’s still lower than without credit constraints.Optimal regulation; Credit constraint; Trade

A versatile resonant tank identificationm methodology for induction heating systems

Induction heating has become the most advance heating process due to benefits, such as efficiency, performance, cleanness, and safety. In this process, the electromagnetic coupling between the induction coil and the induction target is a key, determining the heating performance as well as the resonant power converter operation. This letter proposes an accurate and cost-effective resonant tank identification method applied to induction heating systems. It is based on monitoring the resonant capacitor voltage in order to calculate the resonant tank quality factor. The proposed methodology has been tested using a versatile power electronics test bench applied to domestic induction heating, proving the feasibility of this proposal

Effect of Progesterone, Cortisol and Dhea on the ITR of maedivisna virus transcripcional activity

Estudios previos sugieren que, al igual que en otras infecciones por retrovirus, las hormonas esteroideas serían capaces de dirigir la expresión del virus de Maedi-Visna (MVV) mediante la interacción con los Elementos de Respuesta a Hormona (HRE) de la región promotora/reguladora LTR (Repeticiones Largas Terminales) del genoma del provirus. El objetivo de este trabajo fue la evaluación del efecto del cortisol, progesterona y dehidroepiandrosterona (DHEA) sobre la capacidad transcripcional de la región LTR de MVV mediante ensayos de transfección en fibroblastos ovinos con plásmidos pAcGFP (que contiene el gen para la GFP, proteína verde fluorescente) en los que se había clonado la región U3-cap del LTR de distintas cepas de MVV. La actividad transcripcional del LTR se evaluó a través de la cuantificación de la expresión de la GFP por citometría de flujo con las distintas concentraciones de cada hormona tras 48 horas de incubación. En la mayoría de los ensayos se observó un claro efecto inhibitorio de la transcripción del LTR a elevadas concentraciones hormonales, disminuyendo el efecto a medida que se diluía la hormona, llegando incluso en el caso de cortisol y de DHEA a producirse un incremento de la expresión a partir de 10-7M. En general no se pudo asociar una diferente respuesta con el origen de la cepa estudiada lo que sugiere que no está relacionado con los distintos orígenes/tropismos de los virus. Estos datos sugieren la presencia de un sitio HRE capaz de responder a estimulación hormonal en el LTR de MVV.Previous studies suggest that steroid hormones may direct the expression of Maedi-Visna virus (MVV), as has been observed in other retroviral infections. This would be achieved through the promoter/regulator region of the LTR (long terminal repeats) of the proviral genome, which would contain hormone responsive elements (HRE). The aim of this study was to evaluate the effect of cortisol, progesterone and dehydroepiandrosterone (DHEA) on the transcriptional ability of the MVV LTR region. For this, sheep fibroblasts were transfected with pAcGFP plasmids (containing the gene for green fluorescent protein, GFP) in which the U3-cap region of the LTR of different strains of MVV had been cloned. Different concentrations of each hormone were added to transfected cells and the transcriptional activity of the LTR was evaluated after 48 hours of incubation by quantifying the expression of GFP by flow cytometry. A clear inhibitory effect of the transcriptional ability of the LTR was observed in most of the assays at high hormonal concentrations. This effect decreased with the increasing dilutions of the hormones, to the point that GFP expression was above baseline in cells transfected with several of the plasmids and treated with dilutions above 10-7M of cortisol and DHEA. In general terms, a different response could not be associated to the origin of the strain under study, suggesting that the effect of steroids is not related to the different origins/tropisms of the virus. These data suggest the presence of a hormone responsive element (HRE) in the MVV LTR able to respond to hormonal stimulation

GaN-based matrix resonant power converter for domestic induction heating

Flexible-surface induction cooktops must operate with a variety of induction heating loads with different behavior and power setpoints to be heated simultaneously. In this context, multi-output inverter topologies aim at achieving independent power management while featuring low power-device count and high power density. However, they suffer from limitations when applying classical modulation strategies to ensure soft switching, which is required to reduce transistor losses and achieve efficient operation. In this scenario, wide band-gap devices reduce switching losses, opening a new paradigm in power conversion where soft switching is not mandatory in order to achieve high efficiency. This paper proposes an implementation of a multi-output resonant inverter based on GaN HEMTs and evaluates various modulation strategies in terms of efficiency under different switching modes. The proposed approach is designed and experimentally validated by means of a 2-coil 2000 W prototype implementation

Sizing gold nanoparticles by optical extinction spectroscopy

The measurement of optical extinction is used to determine the size of nearly spherical gold nanoparticles suspended in solution, produced by a 'reverse micelles' process. The contrast between the maximum and the minimum in the extinction spectra around 450 and 520 nm shows a linear dependence with the mean radius of the gold particles less than 3 nm; however, the method can be used to size particles up to 7 nm. Experimental results for extinction spectra can be fitted by Mie's theory if the optical constants from bulk material values are modified by introducing the limitation of the mean free path due to collisions of conduction electrons with the boundary of the nanoparticles.Facultad de Ciencias ExactasCentro de Investigaciones Óptica

Tumor location on electroporation therapies by means of multi-electrode structures and machine learning

Electroporation is a phenomenon produced in the cell membrane when it is exposed to high pulsed electric fields that increases its permeability. Among other application fields, this phenomenon can be exploited in a clinical environment for tumor ablation therapies. In this context to achieve optimum results, it is convenient to focus the treatment on the tumor tissue to minimize side effects. In this work, a pre-treatment tumor location method is developed, with the purpose of being able to precisely target the therapy. This is done by taking different impedance measurements with a multi-output electroporation generator in conjunction with a multi-electrode structure. Data are processed by means of a vector of independent artificial neural networks, trained and tested with simulation data, and validated with phantom gels. This algorithm proved to provide suitable accuracy in spite of the low electrode count compared to the number of electrodes of a standard electrical impedance tomography device

Sizing gold nanoparticles by optical extinction spectroscopy

The measurement of optical extinction is used to determine the size of nearly spherical gold nanoparticles suspended in solution, produced by a 'reverse micelles' process. The contrast between the maximum and the minimum in the extinction spectra around 450 and 520 nm shows a linear dependence with the mean radius of the gold particles less than 3 nm; however, the method can be used to size particles up to 7 nm. Experimental results for extinction spectra can be fitted by Mie's theory if the optical constants from bulk material values are modified by introducing the limitation of the mean free path due to collisions of conduction electrons with the boundary of the nanoparticles.Facultad de Ciencias ExactasCentro de Investigaciones Óptica

TRANSPORTE DE OXÍGENO A TRAVÉS DE PLANTAS ACUÁTICAS

Los experimentos en el laboratorio fueron conducidos para determinar la eficacia de una planta acuática flotante en el mejoramiento en la calidad de un agua residual, basada en su capacidad para transportar oxígeno hacia el efluente. El jacinto de agua como otras plantas acuáticas, transporta O2 a través de sus tejidos dentro de la zona radical, creando así microzonas aerobias alrededor de las raíces. La difusión y el transporte de flujo masivo de O2 vía peciolos y su liberación en la zona radical (Armstrong, 1990) puede incrementar los potenciales redox en el sustrato mejorando la descomposición microbiana y las tasas por nitrificación (Gersberg et al, 1986)

TRANSPORTE DE OXÍGENO A TRAVÉS DE PLANTAS ACUÁTICAS

Los experimentos en el laboratorio fueron conducidos para determinar la eficacia de una planta acuática flotante en el mejoramiento en la calidad de un agua residual, basada en su capacidad para transportar oxígeno hacia el efluente. El jacinto de agua como otras plantas acuáticas, transporta O2 a través de sus tejidos dentro de la zona radical, creando así microzonas aerobias alrededor de las raíces. La difusión y el transporte de flujo masivo de O2 vía peciolos y su liberación en la zona radical (Armstrong, 1990) puede incrementar los potenciales redox en el sustrato mejorando la descomposición microbiana y las tasas por nitrificación (Gersberg et al, 1986)

Escrito en el cuerpo

The Pillow Book, nombre original de la película de Peter Greenaway, es también el título de la compilación de listas poéticas y cortas narraciones de la corte que escribiera Sei Shonagon, cortesana del periodo japonés Heian (siglos X a XII, aproximadamente). The Pillow Book traduciría algo parecido a "Libro de almohada" o "Libro de cabecera", lo que probablemente no fuera más que un nombre genérico alusivo a los escritos ocasionales, producto de la reflexión solitaria en la alcoba, que eran guardados en el pequeño cajón de madera sobre el que se apoyan las almohadas tradicionales japonesas. Sin embargo, el título de esta película no fue traducido literalmente. En cambio, se escogió dar preeminencia a otro rasgo de la película, sin duda el más inquietante: la escritura en el cuerpo. El interés del nombre se desplaza así desde la generalidad de un libro hacia la particularidad de un cuerpo que, en últimas, hará las veces de éste, en tanto será el soporte de una escritura. En la película uno será la encarnación del otro, los dos objetos son, a un mismo tiempo, imágenes idénticas y diametralmente opuestas. Pero, aún más, en el centro de ese nombre dado a la película ya no estará sólo el libro sobre el que se escribe sino la propia escritura, la letra, el trazo, y el goce anudado a ellos. El foco deja de estar exclusivamente en el libro y pasa a estarlo también en la escritura; ya no en el objeto que la sostiene, sino además en su carácter, en su esencia