Diseño de un sistema de anclaje para un tractor con malacate.

This project deals with the design of a winch sprag for the Spider tractor developed at tha National College of Agricultural Engineering in an attempt to provide a cheap source of mechanical power for small farmers of developing countries. Basic sprag design aims at abtaining high pull forces from relatively low mass machines. An attempt was made to create a perfectly rough interfase at the sprag thus maximising the draught force required for soil failure. The position of the sprag was determined by considering longitudinal stabilitj. The experimental results show that soil failure may occur at a lower value of draught than predicted by means of Reece's Fundamental soil Mechanics equation. A simple explanation is that the soil forming the interfase has been disturbed during the first stage of sprag penetration. l-lowever. high pulls were achieved with the sprag utilizing the perfectly rough interface theory.En este trabajo se diseñó un sistema de anclaje para un tractor con malacate desarrollado en el National College of Agricultural Engineering (Inglaterra) con el fin de proporcionar una fuente barata de potencia a los pequeños agricultores de países en desarrollo. En diseño de anclajes se pretende obtener altas fuerzas de tiro utilizando máquinas relativamente livianas. Mediante el diseño propuesto se originó una interfase perfectamente rugosa en Ia espuela, maximizando así la fuerza de tiro requerida para falla del suelo. La posición de la espuela se determinó considerando la estabilidad longitudinal del tractor. Los resultados experimentales muestran que el suelo puede fallar bajo esfuerzos inferiores a los teóricos calculados según la ecuación de Reece. La explicación más sencilla es que el suelo atrapado para formar la interfase ha sido alterado durante la penetración de la espuela. Sin embargo, fue posible obtener altos valores de la fuerza de tiro utilizando la teoría de interfase perfectamente rugosa

Mental health and use of psychoactive substances in colombian adolescents

Introducción. Se ha propuesto una estrecha asociación entre trastornos del afecto y ansiedad en adolescentes con consumo de sustancias. Objetivo. Determinar la prevalencia del consumo de sustancias psicoactivas y los trastornos mentales más frecuentes asociados este consumo, en adolescentes colombianos. Metodología. Estudio transversal, con datos de la Encuesta Nacional de Salud Mental 2015. Con adolescentes entre 12 y 17 años, en quienes se les aplicó CIDI-CAPI (versión 21.1.3) asistida por computador y Assist modificado. Resultados. Se describió información de 408 adolescentes entre 12 y 17 años que reportan consumo de sustancias psicoactivas por lo menos una vez en la vida, siendo una muestra representativa a nivel nacional. Se encontró que la sustancia de mayor consumo fue el alcohol con una prevalencia de 16,6% (IC95% 14,2-19,2), Bogotá constituye la región con mayor consumo de sustancias con una prevalencia de 33,8% (IC95% 24,7-44,2). Ser hombre entre los 16 y 17 años representa un factor de riesgo para consumo de sustancias, así mismo, presentar trastornos del afecto como depresión y ansiedad aumenta 2,28 y 1,62 veces el riesgo de consumo de sustancias psicoactivas respectivamente. Conclusiones. La población adolescente con trastornos del afecto como depresión y ansiedad se encuentra en mayor riesgo de consumir sustancias psicoactivas.Q397-106AdolecentesIntroduction. An association between affective and anxiety disorders has been proposed in adolescents with substance use. Objective. To determine the prevalence of psychoactive substance use and the most frequent mental disorders associated with this consumption, in Colombian adolescents. Methods. This is a cross-sectional study that uses data from the National Mental Health Survey 2015. With adolescents between 12 and 17 years old, in whom CIDI-CAPI (version 21.1.3) was applied by computer and modified ASSIST. Results. A total of 408 adolescents between 12 and 17 years old who reported psychoactive substance use at least once in their lives were described, this group was a representative sample of national population. The most frequent consumed substance was alcohol with a prevalence of 16.6% (95% CI, 14.2-19.2), Bogotá is the region with the highest consumption of substances with a prevalence of 33.8% (IC95 % 24.7-44.2). Otherwise, being a man between 16 and 17 years old represents a risk factor for substance use. Likewise, presenting affective disorders increases by 2.28 times the risk of psychoactive substance use. Conclusions. Adolescents with affective or anxiety disorders are at higher risk of psychoactive substances use, making difficult the treatment and desmonstrating the vulnerability of this population

Photosensitivity Color-Center Model for Ge-Doped Silica Preforms

A new photosensitivity physical model for Ge-doped silica preforms based on color-center photoreactions is presented. Simulation results are in close agreement with experimental results obtained by several condensed matter physics research groups working in this field, suggesting that the photoreactions of this model may, indeed, describe the physical processes involved in Ge-doped silica preform photosensitivity. The proposed photosensitivity model is defined by two differential equations that describe the temporal evolution of a set of color-center concentrations. The first is a modification of a very fast reversible reaction previously proposed by Fujimaki et al., where the reaction precursor has a different chemical structure (it is a neutral oxygen divacancy NODV unrelated to the previously proposed germanium lone pair center GLPC). The chemical structure of this precursor defect explains the generation of nonintrinsic neutral oxygen monovacancy ðNOMVÞ color centers. These centers are transformed into GeE0 defects by means of a second nonlinear reaction. This justifies the slow increase in the absorption peak experimentally measured at 6.3 eV, which had no satisfactory explanation.Ministerio de Ciencia y Tecnología TIC2001-2969-C03-0

Thermal properties and crystallization of iron phosphate glasses containing up to 25 wt% additions of Si-, Al-, Na- and U-oxides

This work is dedicated to the memory of Professor Peter Finlay James, who deceased on 2nd July, 2005.The thermal properties (expansion, Tg and TSOFT.) of glasses, having 56–66% P2O5, 14.8–34.2% Fe2O3 and 2–25 wt% additions of SiO2, Al2O3, Na2O and UO2, were comparatively estimated from dilatometric measurements in similar conditions. The Tg reversibility was clearly verified by varying the heating rates between 1 and 5 °C min−1. From linear equations fits of the various glass properties as functions of the six components it is suggested the iron, sodium and uranium oxides decrease the thermal expansion (for 50 < T ⩽ 300 °C), Tg andTSOFT. From DTA/XRD analysis of three glasses it was confirmed the crystallization tendency decreased with increasing the UO2 level in the glasses. Leaching test data for two compositions containing Na2O suggest addition of UO2 increases the chemical durability of the related glass. The roles of UO2, Na2O and Fe-oxide species as structural components of the glass network are discussed.The authors thank Messrs C. Cotaro, E. Scerbo and J. Menghini [Centro Atómico Bariloche] for the EDS/Edax analysis and leaching tests; Messrs. M. Sanfilippo and A. Heredia for their help in sample preparation; and Dr R.D. Pérez (CEPROCOR, Córdoba) for the X-rays fluorescence analysis. The financial support of the Centro Atómico Bariloche Superconductivity Group, which allowed the purchase of the main parts of the dilatometer is acknowledged. Financial help of J. Ma. Rincón for stage at CAB supported by IAEA, Viena, is much appreciated as well as the financial support of Univ. Nac. de Cuyo and C.O.N.I.C.E.T.Peer reviewe

Inequidad en los años de vida potencial perdida, por departamentos en colombia 1985-2005

Objetivo Describir las diferencias en los años de vida perdidos en la expectativa de vida al nacer por Departamentos en Colombia, durante el periodo de estudio. Métodos Los datos sobre expectativa de vida al nacer por género, fueron tomados del Departamento Administrativo Nacional de Estadística (DAÑE) para los periodos: 1985-1990, 1995-2000 y 2000-2005. Los datos sobre el país con la mejor expectativa de vida en el mundo fue tomado de los reportes de la Organización Mundial de la Salud. Los años de vida perdidos en expectativa de vida (AVPP) fueron estimados a partir de las diferencias relativas entre valores regionales y los mejores valores del mundo para los periodos de estudio. Resultados El número de AVPP tuvo una tendencia a disminuir en ambos géneros durante el periodo de estudio. Sin embargo hubo Departamentos en los cuales los AVPP fueron mayores para mujeres que para hombres en los tres periodos. Adicionalmente, el peor quintil de AVPP tuvo un valor medio de 18,98 ±2,36 AVPP para hombres y 18,45+/-2,43 AVPP para mujeres en 1985-1990; 16,99+/-1,7 AVPP para hombres y 16,01+/1,46 para mujeres en 1995-2000; y 15,99+/-1,34 AVPP para hombres y 14,51 +/-0,96 AVPP para mujeres en 2000-2005. Los valores para el mejor quintil de LLY fueron respectivamente para hombres y mujeres: 7,41+/-0,65; 8,34+/-0,65 en 1985-1990; 7,22+/-0,62 y 8,59+/-0,31 en 1995-2000; y 7,72+/ 0,58 y 8,89+/-0,67 en 2000-2005. Conclusiones Hubo diferencias en la expectativa de vida al nacer entre Departamentos y géneros en los tres periodos estudiados. Hubo disparidad en el numero de AVPP, comparando con el mejor país en el mundo, por Departamentos, durante los periodos de estudio

Nuevos datos cronoestratigráficos de la Fm. Marismas (Bajo Guadalquivir)

La Formación Marismas forma la parte superior del relleno sedimentario del sector SW de la cuenca del Guadalquivir. Los datos previos sobre el sondeo Lebrija, indicaban que la parte más alta de esta formación tenía edades de hasta 9.6 kyr BP y en la parte inferior eran cercanas o fuera del rango del radiocarbono, pero posterior a la reversión Brunhes-Matuyama. En este trabajo se aportan 17 nuevas dataciones realizadas mediante racemización de aminoácidos en valvas de ostrácodos en este mismo sondeo, con el fin de completar la cronología y el modelo de edad de la parte superior e inferior de la Fm Marismas. El resultado indica que el tramo situado por debajo del metro 56, arroja edades que oscilan entre 164685±14110 y 202830±30255, que se correlacionan con los estadios isotópicos marinos MIS 6-7 del Pleistoceno medio, edad sensiblemente más baja a las inferidas para esta formación en otros puntos de la Cuenca del bajo GuadalquivirEste trabajo se ha realizado dentro del proyecto Guadaltyc (Impacto del clima y la tectónica en el registro sedimentario de la Cuenca del Guadalquivir, (CGL2012-30875).Peer Reviewe

Erratum: Competition between covalent bonding and charge transfer at complex-oxide interfaces [Physical Review Letters (2014) 112 (196802)]

Corrección de erratas del artículo "Competition between Covalent Bonding and Charge Transfer at Complex-Oxide Interfaces" (Juan Salafranca, Julián Rincón Javier Tornos, Carlos León, Jacobo Santamaria, Elbio Dagotto,Stephen J. Pennycook, Maria Varela)[Phys. Rev. Lett. 112, 196802 (2014)]Depto. de Estructura de la Materia, Física Térmica y ElectrónicaFac. de Ciencias FísicasTRUEpu

Effect of Lactate on the Microbial Community and Process Performance of an EBPR System

Candidatus Accumulibacter phosphatis is in general presented as the dominant organism responsible for the biological removal of phosphorus in activated sludge wastewater treatment plants. Lab-scale enhanced biological phosphorus removal (EBPR) studies, usually use acetate as carbon source. However, the complexity of the carbon sources present in wastewater could allow other potential poly-phosphate accumulating organism (PAOs), such as putative fermentative PAOs (e.g., Tetrasphaera), to proliferate in coexistence or competition with Ca. Accumulibacter. This research assessed the effects of lactate on microbial selection and process performance of an EBPR lab-scale study. The addition of lactate resulted in the coexistence of Ca. Accumulibacter and Tetrasphaera in a single EBPR reactor. An increase in anaerobic glycogen consumption from 1.17 to 2.96 C-mol/L and anaerobic PHV formation from 0.44 to 0.87 PHV/PHA C-mol/C-mol corresponded to the increase in the influent lactate concentration. The dominant metabolism shifted from a polyphosphate-accumulating metabolism (PAM) to a glycogen accumulating metabolism (GAM) without EBPR activity. However, despite the GAM, traditional glycogen accumulating organisms (GAOs; Candidatus Competibacter phosphatis and Defluvicoccus) were not detected. Instead, the 16s RNA amplicon analysis showed that the genera Tetrasphaera was the dominant organism, while a quantification based on FISH-biovolume indicated that Ca. Accumulibacter remained the dominant organism, indicating certain discrepancies between these microbial analytical methods. Despite the discrepancies between these microbial analytical methods, neither Ca. Accumulibacter nor Tetrasphaera performed biological phosphorus removal by utilizing lactate as carbon source

Ebola Preparedness and Risk in Latin America

Until today, February 22, 2016, no confirmed Ebola cases have been diagnosed in Americas (except USA, four cases with one death). Confusion, lack of knowledge, and fear have led to quickly misclassify cases as suspected, when in fact most of them are false alarms. Nevertheless, European governments summoned to mobilize resources to attend the Ebola outbreak in West Africa. And also Latin American governments should contribute to halt this humanitarian crisis and to be prepared for the potential arrival of this deadly virus in the Caribbean, Central, and South American mainland. In this chapter, we described the experience of preparedness as well as risk assessment done in Latin America regarding the threat of Ebola for the region

Community-associated Methicillin-resistant Staphylococcus aureus, Colombia

Q1Cartas al editor2000-2001To the Editor: Methicillin-resistant Staphylococcus aureus (MRSA) is an established nosocomial pathogen worldwide but more recently has emerged as a highly virulent organism in the community, particularly in the United States (1–3). In Latin America, community-associated MRSA (CA-MRSA) has only been described in the southern area of the continent (Uruguay and Brazil) (4,5). No reports from the Andean region are available. We describe 2 cases of CA-MRSA causing soft-tissue infections (1 severe) in Colombia