The Elasticity of Substitution in Demand for Non-Tradable Goods in Uruguay

This paper`s main goal is to estimate the elasticity of substitution of non-tradable goods, paying special attention to empirical problems related to time-varying parameters, missing regressors and model misspecification. To that end, the paper creates a database and estimates, via three alternative methods, quarterly series of consumption and prices of tradable and non-tradable goods for Uruguay for the period 1983-2002. The econometric estimations of the parameter of interest were performed with VEC models. These estimates give a long-run elasticity of substitution of %0. 46 in the principal model and %0. 71 and %0. 75 in the two alternative models. Parametric stability tests are performed on the principal model, and the predictive ability of the model is also tested. It is concluded that, not only is the parameter of interest stable over time, but the model also has good predictive properties, even when tested in a very demanding environment: the period following Uruguay`s change of exchange rate regime in mid-2002.

Modeling And Detection Of Uterine Contractions Using Magnetomyography

In this dissertation, we develop a novel mathematical framework for modeling and analyzing uterine contractions using biomagnetic measurements. The study of myometrium contractility during pregnancy is relevant to the field of reproductive assessment. Its clinical importance is grounded in the need for a better understanding of the bioreproduction mechanisms. For example, in the last decade the number of preterm labors has increased significantly. Preterm birth can cause health problems or even be fatal for the fetus if it happens too early, and, at the same time, it imposes significant financial burdens on health care systems. Therefore, it is critical to develop models and statistical tools that help to monitor non-invasively the uterine activities during pregnancy. We derive a forward electromagnetic model of uterine contractions during pregnancy. Existing models of myometrial contractions approach the problem either at an organ level or lately at a cellular level. At the organ level, the models focus on generating contractile forces that closely resemble clinical measurements of normal intrauterine pressure during contractions in labor. At the cellular level, the models focus on predicting the changes of ionic concentrations in a uterine myocyte during a contraction, and, as a consequence, on modeling the transmembrane potential evolution as a function of time. In this work, we propose an electromagnetic modeling approach taking into account electrophysiological and anatomical knowledge jointly at the cellular, tissue, and organ levels. Our model aims to characterize myometrial contractions using magnetomyography: MMG) and electromyography: EMG) at different stages of pregnancy. In particular, we introduce a four-compartment volume conductor geometry, and we use a bidomain approach to model the propagation of the myometrium transmembrane potential on the human uterus. The bidomain approach is given by a set of reaction-diffusion equations. The diffusion part of the equations governs the spatial evolution of the transmembrane potential, and the reaction part is given by the local ionic current cell dynamics. Here we introduce a modified version of the Fitzhugh-Nagumo: FHN) equation for modeling ionic currents in each myocyte, assuming a plateau-type transmembrane potential. We incorporate the anisotropic nature of the uterus by considering conductivity tensors in our model. In particular, we propose a general approach to design the conductivity-tensor orientation and to estimate the conductivity-tensor values in the extracellular and intracellular domains for any uterine shape. We use finite element methods: FEM) to solve our model, and we illustrate our approach by presenting a numerical example to model a uterine contraction at term. Our results are in good agreement with the values reported in the experimental technical literature, and these are potentially important as a tool for helping in the characterization of contractions and for predicting labor. We propose an automatic, robust, single-channel statistical detector of uterine MMG contractions. One common restriction of previous techniques is that algorithm parameters, such as the detection threshold and the window length of analysis need to be calibrated experimentally, based on a particular data set. Therefore, the detection performance might change from patient to patient, for example, because of differences in the pregnancy stage and tissue conductivities. In contrast, the proposed algorithm does not require the use of a sliding window of analysis, and the detection threshold is determined analytically; thus, it does not need to be calibrated. Our detection algorithm consists of two stages: In the first stage, we segment the measurements using a multiple change-point estimation algorithm and assuming a piecewise constant time-varying autoregressive model of the measurements; In the second stage, we apply the non-supervised K-means cluster algorithm to classify each time segment, using the RMS and FOZC as candidate features. As a result a discrete-time binary decision signal is generated indicating the presence of a contraction. Moreover, since each single channel detector provides local information regarding the presence of a contraction, we propose a spatio-temporal estimator of the magnetic activity generated by uterine contractions. The algorithm, when evaluated with real MMG measurements, detects uterine activity much earlier than the patient begins to sense it. It also enables visualizing the relative location of the origin of uterine contraction and quantifying the amount of energy delivered during a contraction. These results are important in obstetrics, e.g., as a tool for helping to characterize contractions and to predict labor. For the aforementioned problem of multiple change-point estimation, a class of one-dimensional segmentation, we also compute fundamental mathematical results for minimal bounds on mean-square error estimation. Indeed, if an estimator is available, the evaluation of its performance depends on knowing whether it is optimal or if further improvement is still possible. In our segmentation problem the parameters are discrete therefore the conventional Cramer-Rao bound does not apply. Hence, we derive Barankin-type lower bounds, the greatest lower bound on the covariance of any unbiased estimator, which are applicable to discrete parameters. The computation of the bound is challenging, as it requires finding the supremum on a finite set of symmetric matrices with respect to the Loewner ordering, which is not a lattice order. Therefore, we discuss the existence of the supremum, propose a minimal upper-bound by using tools from convex geometry, and compute closed-form solutions for the Barankin information matrix for several distributions. The results have broad biomedical applications, such as DNA sequence segmentation, MEG and EEG segmentation, and uterine contraction MMG detection, and they also have applications for signal segmentation in general, such as speech segmentation and astronomical data analysis

A Comment on Bonnor-Steadman Closed Timelike Curves

The existence and stability closed timelike curves in a Bonnor-Ward spacetime without torsion line singularities is shown by exhibiting particular examples.Comment: 2 pages, RevTex, minor correction

Moléculas de origen natural con capacidad anti agregante de α-sinucleina in vitro

Tesis (Tecnólogo Médico, mención bioanálisis clínico, inmunohematología y banco de sangre)La Enfermedad de Parkinson es uno de los trastorno neuro-degenerativo progresivo del sistema nervioso central que afecta aproximadamente a 4 millones de personas en todo el mundo[1]. Esta enfermedad se caracteriza por la degeneración selectiva de las neuronas dopaminérgicas y debido a la pérdida de función pre sináptica de la proteína α-sinucleína, proceso clave en el desarrollo de la enfermedad [2]. Cuando falla el plegamiento correcto de esta proteína, se produce una agregación anormal dando origen a inclusiones denominados cuerpos de Lewy, los cuales se encuentran en el cerebro de pacientes con la enfermedad de Parkinson [3]. Estos cuerpos contribuyen colectivamente a los síntomas motores de la enfermedad de Parkinson, tales como: temblor en reposo, bradicinesia, y rigidez del tono muscular de las personas que presentan la enfermedad[4]. Estudios han revelado que estas proteínas defectuosas pueden trasladarse a otras células, afectando de esta forma las células sanas que las rodean causando su destrucción[5]. Hasta ahora el método de referencia para el tratamiento en pacientes que sufren síntomas de Parkinson es Levodopa, sin embargo, en tratamientos prolongados los pacientes presentan manifestaciones secundarias como disquinesia comprometiendo más la calidad de vida de estos pacientes [6]. A pesar de los esfuerzos desplegados, no ha sido posible desarrollar un tratamiento no sólo efectivo sino que no presente efectos secundarios para los pacientes. Hasta ahora existen evidencias al menos in vitro, de que las moléculas aisladas de origen natural, tales como polifenoles, poseen un efecto 8 sobre la agregación de α sinucleína [7] [3], aspecto importante dentro del desarrollo de la enfermedad, a pesar que aún no posible elucidar claramente como estas moléculas estarían interactuando con determinados residuos de α-sinucleína, al menos evitarían que estos mismos continúen siendo tóxicos ([3]). Por lo tanto, proponemos en esta unidad de investigación mediante ensayos de fluorescencia por ThT, determinar la capacidad inhibitoria de polifenoles tipo catecoles, sobre el proceso de agregación de la α-sinucleína. En donde uno de los compuestos a utilizar que fue la clovamida obtuvo los efectos antiagregantes que se esperaban, mientras que el otro compuesto que fue el ácido rosmarino no presento actividad antiagregante

FACTORES SOCIODEMOGRÁFICOS ASOCIADOS A LA DISCONTINUACIÓN DE MÉTODOS ANTICONCEPTIVOS EN LOS PRIMEROS 12 MESES EN MUJERES EN EL DEPARTAMENTO DE LIMA SEGÚN ENDES 2022

Introducción: La discontinuación del uso de métodos anticonceptivos, en mujeres es una problemática a nivel internacional, que puede desencadenar embarazos no deseados, enfermedades de transmisión sexual y crear condiciones de vida deficientes para madres e hijos, siendo necesario el estudio de los factores que influyen en estas conductas Objetivo: Determinar la asociación entre los factores sociodemográficos y la discontinuación de métodos anticonceptivos en los primeros 12 meses en mujeres en el Departamento de Lima según ENDES 2022. Método: Es un estudio de diseño tipo observacional, analítico-transversal, retrospectivo utilizando una base de datos secundaria la Encuesta Demográfica y de Salud Familiar del 2022, seleccionando como una población de estudio a 3084 mujeres en torno a los criterios de elegibilidad. Resultados: el estado civil, permitió asociar que los que no viven juntos (RPa=1.142, IC 95% [1.062 - 1.127], p=0.000) y las mujeres divorciadas (RPa=1.314, IC 95% [1.222 - 1.413], p=0.000) eran las que mayor probabilidad de discontinuación presentaban. Conclusiones: Se concluyó que los que no viven juntos y son divorciadas, aumenta la probabilidad de abandono del método anticonceptivo en los primeros 12 meses en las mujeres en el Departamento de Lima

An Analysis of Irrigation Organizations in Colombia through the Prism of Collective Action

The objective of this article is to deepen the knowledge of collective action in irrigation organizations in Colombia, by identifying the limitations of the members for their organizational work and the variables of context that determine collective behavior. Human and environmental factors have not been sufficiently considered in public irrigation policies, since, in the case of Colombia, these have focused almost exclusively on the physical infrastructure. The methodology develops a qualitative approach based on an ethnographic and quantitative study of the socioeconomic characteristics of irrigation users. The results allow us to affirm that the collective awareness of water is a common good. The vision of the associates about the associative work, the conformation and structuring of the organizations, the nature of the established agreements, and the socio-economic, environmental, and political environment of the organizations studied, are determining factors of their collective action and, therefore, should be taken into account in public policies of associative irrigation

The institutionalized Buen Vivir: a new hegemonic political paradigm for Ecuador

Buen Vivir has recently emerged in Latin America as an alternative societal model to the historical liberal (or neoliberal) and Marxist ones. The article focuses on its Ecuadorian variant and, more specifically, the institutionalized version embodied in the 2008 Constitution and the policies of the Citizens’ Revolution governments. This version is the particular result of the convergence of three different currents and has become the hegemonic ideology in the country. The article describes its main thematic axes and appraises its originality, as well as the theoretical and practical contributions

An electro-rheological study of the nematic liquid crystal 4-n-heptyl-4'-cyanobiphenyl

An experimental and theoretical study of the electro-rheological effects observed in the nematic phase of 4-n-heptyl-4'-cyanobiphenyl has been conducted. This liquid crystal appears to be a model system, in which the observed rheological behaviour can be interpreted by the Leslie-Ericksen continuum theory for low molecular weight liquid crystals. Flow curves are illustrated at different temperatures and under the influence of an external electric field ranging from 0 to 3 kV mm-1, applied perpendicular to the direction of flow. Also presented is the apparent viscosity as a function of temperature, over similar values of electric field, obtained at different shear rates. A master flow curve has been constructed for each temperature by dividing the shear rate by the square of the electric field and multiplying by the square of a reference value of electric field. In a log-log plot, two Newtonian plateaux are found to appear at low and high shear rates, connected by a shear-thinning region. We have applied the Leslie-Ericksen continuum theory, in which the director alignment angle is a function of the electric field and the flow field boundary conditions are neglected, to determine viscoelastic parameters and the dielectric anisotropy