“Too soon?, too soon?” or the dilemma of reopening centralist countries in the times of COVID-19.

Conforme pasa el tiempo, cada país debe enfrentar lo desconocido en cuanto al equilibrio entre las medidas de distancia social y la reapertura de la economía de manera segura. Algunos países son ventanas al futuro, pero las experiencias de nuestros vecinos son las más adecuadas para anticipar algunos aspectos de nuestra realidad en unas pocas semanas. Algunas áreas más afectadas en los Estados Unidos, donde las disparidades sociales explican la enorme brecha interracial de mortalidad por COVID-19, son claros ejemplos de cómo la desigualdad puede dividir las trayectorias de diferentes grupos de población en un mismo país. Además, las horripilantes imágenes de Guayas (Ecuador), Manaos (Brasil) o Loreto (Perú) mostraron al mundo las consecuencias de años de bajas inversiones en salud cuando una pandemia golpea las áreas más vulnerables.As time flies, every country must face the unknown regarding the balance between social distance measures and reopening the economy safely. Some countries are windows to the future, but the experiences of our neighbors are best suited to anticipate some aspects of our reality in a few weeks. Some hard-hit areas in the United States, where social disparities explain the huge inter-racial gap of mortality from COVID-19, are clear examples of how inequality can divide the trajectories of different population groups in the same country. Furthermore, the gruesome images from Guayas (Ecuador), Manaos (Brazil), or Loreto (Peru) showed the world the consequences of years of low health-care investments when a pandemic strikes in the most vulnerable areas

Identificación de los nemátodos de mayor prevalencia en bovinos de pequeños productores del municipio de Dosquebradas.

La determinación y tipificación de los nemátodos gastrointestinales de mayor prevalencia de los bovinos de pequeños productores del municipio de Dosquebradas, se realizó por medio de un muestreo significativo de heces fecales de los bovinos de 4 veredas del municipio, teniendo en cuenta la cantidad de limitantes que existen a nivel de planes sanitarios, conocimiento de especies parasitarias y uso inadecuado o no uso de desparasitan tés sin un diagnóstico previo de las especies infectantes. Dentro de las características principales de la zona en la cual se trabajó, se debe mencionar que Dosquebradas es un municipio que está ubicado a una altitud de los 1520 msnm, con una temperatura promedio de 24ºc y una precipitación media de 2550 mm/a. Teniendo en cuenta la descripción de la zona sobre la cual se trabajó, y más específicamente en las 4 veredas, se realizó un muestreo aleatorio de materia fecal de aproximadamente 86 bovinos para realizar un estudio cualitativo de los huevos de nemátodos hallados en el laboratorio de parasitología. Se identificaron las características morfológicas de los huevos de nematodos encontrados, y se seleccionaron los vermes de mayor incidencia entre la población bovina muestreada, como es el caso de: Haemonchus sp, Trichostrongylus sp y Trichuris sp con la finalidad de realizar un adecuado plan de desparasitación en el municipio de Dosquebradas como componente de extensión rural

Revisiting the Relationship of Transient-storage and Aggregated Dead Zone Models of Longitudinal Solute Transport in Streams

Eco-Hydraulics and Eco-Hydrolog

Low temperature magnetic transitions of single crystal HoBi

We present resistivity, specific heat and magnetization measurements in high quality single crystals of HoBi, with a residual resistivity ratio of 126. We find, from the temperature and field dependence of the magnetization, an antiferromagnetic transition at 5.7 K, which evolves, under magnetic fields, into a series of up to five metamagnetic phases.Comment: 5 pages, 5 figure

Numerical estimation of the geometry and temperature of an alternating current steelmaking electric arc

A channel arc model (CAM) that predicts the temperature and the geometry of an electric arc from its voltage and impedance set-points is presented. The core of the model is a nonlinear programming (NLP) formulation that minimizes the entropy production of a plasma column, the physical and electrical properties of which satisfy the Elenbaas–Heller equation and Ohm's law. The radiative properties of the plasma are approximated utilizing the net emission coefficient (NEC), and the NLP is solved using a global numerical solver. The effects of the voltage and impedance set-points on the length of the electric arc are studied, and a linear formula that estimates the length of the arc in terms of its electrical set-points is deducted. The length of various electric arcs is measured in a fully operative electric arc furnace (EAF), and the results are used to validate the proposed models. The errors in the predictions of the models are 0.5 and 0.4 cm. In comparison, the existing empirical and Bowman formulae estimate the length of the experimental arcs with errors of 2.1 and 2.6 cm. A simplified formula to estimate the temperature of an electric arc in terms of its electrical set-points is also presented

Modeling and energy efficiency analysis of the steelmaking process in an electric arc furnace

This paper presents a comprehensive model of an industrial electric arc furnace (EAF) that is based upon several rigorous first-principles submodels of the heat exchange in the EAF and practical experience from an industrial melt shop. The model is suited for process simulation, optimization, and control applications. It assumes that the energy demand of the process is satisfied by six sources, the electric arc, the oxy-fuel burners, the oxygen lances, the combustion of coal, and the oxidation of metal in the liquid and in the solid phase. The energy exchange between the liquid and the solid phase due to liquid metal splashing is also considered. The different mechanisms of heat exchange are represented in the model as follows: (a) the radiative heat exchange from the arc to the other phases is computed using the DC circuit analogy, where the view factors are calculated using exact formulae and Monte-Carlo algorithms. (b) The energy input from the oxy-fuel burner is modeled using simplified geometries for which heat transfer relationships are known. (c) The amount of heat released by the oxidation of solid metal is described by the quadratic corrosion formula. (d) The energy exchange from the bath to the solid phase due to splashing is modeled using relationships and experimental data that are available in the literature. The model contains the melting rates and the efficiency of the oxygen lancing as free parameters; their values were computed by a least squares fit to process data of an industrial Ultra-High-Power EAF. In comparison with existing EAF models, the model presented here describes the dynamic behavior of the melting process more realistically. Based on the model, time-dependent energy efficiency curves for the various contributions and for the overall process are computed and discussed