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Monteria, Colombia

Bernal-Correa R.,Sinu University | Morales-Acevedo A.,CINVESTAV | Montes-Monsalve J.,National University of Colombia | Pulzara-Mora A.,National University of Colombia
Journal of Physics D: Applied Physics | Year: 2016

Modelling solar cells has, in recent years, become a fundamental tool for their optimum design. Here, we present an optical study of CuInGaSe2 (CIGS) solar cells in order to improve them by selecting the appropriate transparent conductive oxide (TCO) layer thickness. The system of interest in our case was glass/TCO/CdS/CIGS/Mo, considering radiation incident perpendicular to the cell from the glass and taking into account the absorbent nature of the TCO, CdS and CIGS layers. The reflectance of this layered system was calculated using the optical matrix method considering the three absorbent layers and the reflectance at the Mo substrate. In addition, the transmittance of the TCO layer was also calculated. Then, having the constant thickness of the CIGS (1 μm) and CdS (0.1 μm) layers, the weighted average of the cell reflectance and the TCO transmittance in the AM1.5 solar spectrum were calculated for different TCO thickness in the range from 0.1 to 1 μm. Finally, we defined a figure of merit that involves the total cell reflectance, the transmittance and the sheet resistivity of the TCO as a function of the TCO layer thickness. Our results indicate that the ZnO film thickness can be increased to 1 μm with a possible improvement of the cell performance compared to cells with typical TCO thickness around 500 nm. © 2016 IOP Publishing Ltd. Source

Aedes (Stegomyia) albopictus has been identified for the first time in the municipality of La Tebaida (Quindio department of Colombia), an area with active transmission of dengue fever by Ae. (Stegomyia) aegypti. Specimens of Ae. albopictus were detected in a tire used as an ovitrap in a remnant of bamboo plantation in a rural area of the municipality of La Tebaida; Ae. aegypti presented co-occurrence and both species were molecularly typed using cytochrome oxidase I (DNA barcode region). The first DNA barcode sequences were recorded for 13 Colombian specimens of Ae. albopictus, identifying an asiatic origin (Singapore) and demonstrating the utility of this method for molecular identification. These sequences can be used to identify genetic flow with other populations in Colombia, in ecological studies, and in studies of vector incrimination in outbreaks of emerging and re-emerging arbovirus in Colombia. © 2015, Sociedad Colombiana de Entomologia. All rights reserved. Source

Gonzalez-Parra G.,University of Los Andes, Venezuela | Gonzalez-Parra G.,University of Texas at Arlington | Arenas A.J.,University of Cordoba, Colombia | Arenas A.J.,Sinu University | Chen-Charpentier B.M.,University of Texas at Arlington
Mathematical Methods in the Applied Sciences | Year: 2013

In this paper,we propose a nonlinear fractional order model in order to explain and understand the outbreaks of influenza A(H1N1). In the fractional model, the next state depends not only upon its current state but also upon all of its historical states. Thus, the fractional model is more general than the classical epidemic models. In order to deal with the fractional derivatives of the model, we rely on the Caputo operator and on the Grünwald-Letnikov method to numerically approximate the fractional derivatives. We conclude that the nonlinear fractional order epidemic model is well suited to provide numerical results that agree very well with real data of influenza A(H1N1) at the level population. In addition, the proposedmodel can provide useful information for the understanding, prediction, and control of the transmission of different epidemics worldwide. Copyright © 2013 John Wiley & Sons, Ltd. Source

Gonzalez-Parra Gilberto G.,University of Los Andes, Venezuela | Arenas A.J.,Sinu University | Cogollo M.R.,EAFIT University
WSEAS Transactions on Biology and Biomedicine | Year: 2013

This paper deals with the construction of piecewise analytic approximate solutions for nonlinear initial value problems modeled by a system of nonlinear ordinary differential equations. In real world several biological and environmental parameters in the predator-prey model vary in time. Thus, non-autonomous systems are important to be studied. We show the effectiveness of the method for autonomous and non-autonomous predator-prey systems. The method we have used is called the differential transformation method which has some suitable properties such as accuracy, low computational cost, easiness of implementation and simulation as well as preserving properties of the exact theoretical solution of the problem. The accuracy of the method is checked by numerical comparison with fourth-order Runge-Kutta results applied to several predator-prey examples. Source

A model construction tolos visibility of rights and citizenem powerment was generated front to defense and en forcé ability of the same, from the construction and communication of patient rights charters in Cartagena. Methodological successes in the experiences of health rights charters of Mexico, Italy and Europe were considered. The metodology includes five phases, preparation, legal fundamentation, citizensurvey, case analysis and participatory workshops. The model, in her its the approachused in the construction of the charter in health rights from Cartagenade Indias, which mixes legal aspects (inventory of articles of the constitution, laws and Colombian regulations) and theusers' perception (Citizensurvey and study cases). Source

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