Dynamic properties of a building with viscous dampers in non-proportional arrangement

Any rational approach to define the configuration and size of viscous fluid dampers in a structure should be based on the dynamic properties of the system with the dampers. In this paper we propose an alternative representation of the complex eigenvalues of multi degree of freedom systems with dampers to calculate new equivalent natural frequencies. Analytical expressions for the dynamic properties of a two-story building model with a linear viscous damper in the first floor (i.e. with a non-proportional damping matrix) are derived. The formulas permit to obtain the equivalent damping ratios and equivalent natural frequencies for all the modes as a function of the mass, stiffness and damping coefficient for underdamped and overdamped systems. It is shown that the commonly used formula to define the equivalent natural frequency is not applicable for this type of system and for others where the damping matrix is not proportional to the mass matrix, stiffness matrix or both. Moreover, the new expressions for the equivalent natural frequencies expose a novel phenomenon; the use of viscous fluid dampers can modify the vibration frequencies of the structure. The significance of the new equivalent natural frequencies is expounded by means of a simulated free vibration test. The proposed approach may offer a new perspective to study the effect of viscous dampers on the dynamic properties of a structur

Strategies for use, treatment, management and final disposition of wastes in academic laboratories

Laboratory higher education institutions can generate a wide range of wastes,many of which have hazardous characteristics. The uncontrolled accumulation of such wastes also has a significant impact on the environment, safety and health of the academic community. This work formulates strategies that allow the development of integrated solutions to mitigate the latent risk for the community at Institución Universitaria Colegio Mayor de Antioquia,Colombia, and its surroundings. Therefore, it is considered to quantify the generation of waste in the units of analysis of different experimental spacesand evaluate the factors involved in the implementation of strategies for diagnosis, waste recovery, treatment, and final disposition. Based on the diagnosis and characterization of wastes, alternatives are evaluated that help to prevent and, in other cases, mitigate the impacts that they can cause, in order to consolidate a protocol for waste management. Hazardous waste disposition strategies, treatment mechanisms and minimization strategies, such as microchemistry, precipitation recycling, encapsulation and immobilization methods, evaporation as well as solvent recovery, have been implemented

White-footed tamarin Saguinus leucopus GUNTHER 1876: some biological aspects and issues of veterinary interest about the species

P?ginas 82-89Recurso electr?nicoEl tit? gris Saguinus leucopus es una especie de primate neotropical end?mico de la regi?n norte de Colombia y el piedemonte de la cordillera central vulnerable (VU) seg?n su estatus de conservaci?n, debido al tr?fico ilegal y a la p?rdida de su h?bitat. El escaso conocimiento cient?fico de la especie, se limita a ciertos aspectos de su ecolog?a e historia natural, aunque en la actualidad se ha despertado un gran inter?s por la investigaci?n de la especie en diferentes campos con el fin de contribuir a su conservaci?n. El objetivo de este trabajo fue hacer una revisi?n de algunos aspectos de inter?s veterinario en S. leucopus, como datos de su fisiolog?a e historia de vida, lo cual pueda servir de base para investigaciones futuras que lleven a mejorar el manejo de la especie in situ y ex situ.ABSTRACT. The white footed tamarin Saguinus leucopus is a neotropical primate species endemic to the northern region of Colombia and the foothills of the central mountain range and it is vulnerable (VU) according to their conservation status, due to illegal trafficking and loss of habitat. The limited scientific knowledge of the species, is limited to certain aspects of its ecology and natural history, but today there has been a great interest in the investigation of the species in different fields to contribute to their conservation. The aim of this study was to review some aspects of veterinary interest in S. leucopus, as data from physiology and life history, which can serve as a basis for further research leading to improved management of the species in situ and ex situ

An effective procedure to design the layout of standard and enhanced mode-S multilateration systems for airport surveillance

In this paper, an effective procedure to emplace standard and enhanced mode-S multilateration stations for airport surveillance is studied and developed. This procedure is based on meta-heuristic optimization techniques, such as genetic algorithm (GA), and is intended to obtain useful parameters for an optimal system configuration that provides acceptable performance levels. Furthermore, the procedure developed here is able to evaluate and improve previous system designs, as well as possible system enhancements. Additionally, the design strategies to be used along with the procedure proposed here are fully described. Parameters such as the number of stations, the system geometry, the kind of measurements to be used, and the system accuracy are obtained taking into account the basic requirements such as the Line of Sight, the probability of detection, and the accuracy levels. © Cambridge University Press and the European Microwave Association, 2012

Patrones de prescripción de hipolipemiantes en pacientes de Colombia

Introduction. Lipid-lowering drugs, especially statins, have shown great relevance in preventing and treating cardiovascular diseases.Objective. To determine the prescription patterns of lipid-lowering drugs and the variables associated with their use in a Colombian population.Materials and methods. This is a cross-sectional descriptive study. From a drug dispensing database of approximately 4.5 million Colombian health system affiliates, patients of all ages and both sexes treated with lipid-lowering agents (statins, fibrates, ezetimibe) were identified between January and March, 2017. Demographic, pharmacological and co-medication variables were included.Results. In total, 103,624 patients were identified as being treated with lipid-lowering agents. The average age was 67.5 years, and 49.8% were 65 years or older. Women comprised 58.0% of the patients. Statins were the most used (n=96,910; 93.5%), and atorvastatin (n=80,812; 78.0%) and lovastatin (n=12,621; 12.2%) were the most frequent. The mean atorvastatin dose was 30.3 mg/day, and 49.9% of its users received presentations of 40 mg or more. A total of 9,258 (8.9%) patients received fibrates, and only 780 (0.8%) were taking ezetimibe. Of this population, 94.9% were treated with lipid-lowering monotherapy, and 97.3% (n=100,813) had co-medication for their comorbidities, with the most frequent being antihypertensive (89.1%), antiplatelet (57.8%), antidiabetic (31.5%) and antiulcerative agents (34.2%).Conclusions. Atorvastatin is currently the most frequently used lipid-lowering drug in this group of Colombian patients, especially in monotherapy and at doses close to the defined daily dose. Only half received high-intensity doses. New studies are required to verify the efficacy of these therapies.Introducción. Los fármacos hipolipemiantes, especialmente las estatinas, han demostrado gran relevancia para la prevención y el tratamiento de las enfermedades cardiovasculares.Objetivo. Determinar los patrones de prescripción de los fármacos hipolipemiantes y las variables asociadas con su uso en una población de Colombia.Materiales y métodos. Se trata de un estudio descriptivo y transversal. A partir de una base de datos de dispensación de medicamentos de 4,5 millones de afiliados al sistema de salud de Colombia, se identificaron los pacientes de cualquier edad y sexo en tratamiento con hipolipemiantes (estatinas, fibratos, ezetimibe), entre enero y marzo de 2017. Se incluyeron variables demográficas, farmacológicas y de comedicaciones. Resultados. Se identificaron 103.624 pacientes en tratamiento con hipolipemiantes. La edad promedio fue de 67,5 años y el 49,8 % tenía 65 o más años. El 58,0 % eran mujeres. Las estatinas fueron los más utilizados (n=96.910; 93,5 %), siendo la atorvastatina (n=80.812; 78,0 %) y la lovastatina (n=12.621; 12,2 %) las más frecuentes. La dosis promedio de atorvastatina fue de 30,3 mg/día y el 49,9 % de sus usuarios recibía presentaciones de 40 mg o más. Un total de 9.258 (8,9 %) pacientes recibían fibratos y solo 780 (0,8 %) tomaban ezetimibe. El 94,9 % de casos recibió tratamiento en monoterapia hipolipemiante y el 97,3 % (n=100.813) tenía comedicaciones para comorbilidades, siendo las más frecuentes antihipertensivos (89,1 %), antiagregantes plaquetarios (57,8 %), antidiabéticos (31,5 %) y antiulcerosos (34,2 %).Conclusiones. La atorvastatina es actualmente el medicamento hipolipemiante más utilizado en este grupo de pacientes de Colombia, especialmente en monoterapia y a dosis cercanas a las definidas, aunque solo la mitad recibían dosis recibían dosis de alta intensidad. Se requieren nuevos estudios que verifiquen la efectividad de estos tratamientos

Diseño de filtros corrugados mediante la técnica de enjambre de partículas

En este artículo se presenta la experiencia en la aplicación de la técnica de optimización de enjambre de partículas o PSO (Particle Swarm Optimization) al diseño de filtros corrugados en guía de onda. Los resultados obtenidos indican que esta técnica permite realizar diseños que se adaptan a una máscara de filtrado predeterminada con una alta convergencia hacia la solución óptima

Evaluación del efecto tóxico de los extractos vegetales acuosos Barbasco (Phyllantus sp.) Neem (Azadirachta indica) y Marigol (Tagetes patula) sobre los microorganismos Trichoderma sp. y Metarhizium sp.

El experimento se llevó a cabo en el Laboratorio de Fitopatología del Centro de Investigación Natfaima de Corpoica, localizado en el municiplo de El Espinal, departamento del Tolima, entre los meses de marzo y agosto de 2003, Para la piueba se utilizaron extractos vegetales acuosos de Neem (Azadirachía indican), Marigol (Tagetes patula)] y Barbasco [Phylanthus ichihyomelhlus) y los microorganismos biocontroladores Irichoderma sp y Metarhizium so. Bajo condiciones de laboratorio se evaluaron cinco concentraciones (0%. 5%, 10%, 15% y 20%) de cada uno de los tres extractos Gicuosos, frente al crecimiento de los dos microorganismos biocontroladores. Se evaluaron las variables tasa de crecimiento (Crecimiento radial de los hongos biocontraladores) y el valor de la concentración mínima de inhibición. Se ulilizó un diseño completamente al azar y las observaciones se analizaron mediante pruebas de regresión y correlación. En conclusión se puede afirmar que ninguno de los tres extractos en las concentraciones evaluadas, afectan severamente a los hongos Metarhizium so. y Trichoderma sal y que tanto el Neern como el Margo! en concentaciones superiores al 20% puede lener un efecto funguiciaa contra el hongo Trchoaerma so. Igualmente con respecto a Marigel, es posible que en concentraciones más altas, tenga efectos tóxicos sobre el Metarhizlumn sp

Effect of an Albumin Infusion Treatment Protocol on Delayed Cerebral Ischemia and Relevant Outcomes in Patients with Subarachnoid Hemorrhage

Un protocolo de manejo institucional para pacientes con hemorragia subaracnoidea (HSA) basado en la evaluación cardíaca inicial, la permisividad de los balances negativos de líquidos y el uso de una infusión continua de albúmina como fluidoterapia principal durante los primeros 5 días de estancia en la unidad de cuidados intensivos (UCI). se implementó en nuestro hospital en 2014. Tenía como objetivo lograr y mantener la euvolemia y la estabilidad hemodinámica para prevenir eventos isquémicos y complicaciones en la UCI reduciendo los períodos de hipovolemia o inestabilidad hemodinámica. Este estudio tuvo como objetivo evaluar el efecto del protocolo de manejo implementado sobre la incidencia de isquemia cerebral retardada (ICD), la mortalidad y otros resultados relevantes en pacientes con HSA durante la estancia en la UCI.Q1Background An institutional management protocol for patients with subarachnoid hemorrhage (SAH) based on initial cardiac assessment, permissiveness of negative fluid balances, and use of a continuous albumin infusion as the main fluid therapy for the first 5 days of the intensive care unit (ICU) stay was implemented at our hospital in 2014. It aimed at achieving and maintaining euvolemia and hemodynamic stability to prevent ischemic events and complications in the ICU by reducing periods of hypovolemia or hemodynamic instability. This study aimed at assessing the effect of the implemented management protocol on the incidence of delayed cerebral ischemia (DCI), mortality, and other relevant outcomes in patients with SAH during ICU stay. Methods We conducted a quasi-experimental study with historical controls based on electronic medical records of adults with SAH admitted to the ICU at a tertiary care university hospital in Cali, Colombia. The patients treated between 2011 and 2014 were the control group, and those treated between 2014 and 2018 were the intervention group. We collected baseline clinical characteristics, cointerventions, occurrence of DCI, vital status after 6 months, neurological status after 6 months, hydroelectrolytic imbalances, and other SAH complication. Multivariable and sensitivity analyses that controlled for confounding and considered the presence of competing risks were used to adequately estimate the effects of the management protocol. The study was approved by our institutional ethics review board before study start. Results One hundred eighty-nine patients were included for analysis. The management protocol was associated with a reduced incidence of DCI (hazard ratio 0.52 [95% confidence interval 0.33–0.83] from multivariable subdistribution hazards model) and hyponatremia (relative risk 0.55 [95% confidence interval 0.37–0.80]). The management protocol was not associated with higher hospital or long-term mortality, nor with a higher occurrence of other unfavorable outcomes (pulmonary edema, rebleeding, hydrocephalus, hypernatremia, pneumonia). The intervention group also had lower daily and cumulative administered fluids compared with historic controls (p < 0.0001). Conclusions A management protocol based on hemodynamically oriented fluid therapy in combination with a continuous albumin infusion as the main fluid during the first 5 days of the ICU stay appears beneficial for patients with SAH because it was associated with reduced incidence of DCI and hyponatremia. Proposed mechanisms include improved hemodynamic stability that allows euvolemia and reduces the risk of ischemia, among others.Revista Internacional - IndexadaS

Actividad antioxidante de extractos metanólicos de attalea butyracea

Se extrajeron pigmentos de Attalea butyracea y se evaluó su contenido de fenoles, antocianinas y su capacidad atrapadora de los radicales libres DPPH•, encontrándose un Ic50 de 141.4 mg/l y una constante cinética k de 1.0512E-05 (g/L)-1s-1, en la evaluación de la capacidad atrapadora de los radicales superóxido (CARS) se encontró un Ic50 de 76 mg/L y la capacidad de inhibir la oxidación del β-caroteno fue pobre. Como patrones de referencia se utilizó BHA para DPPH• y β-caroteno, con un Ic50 de 5.6 mg/L y una k de 3.0372E-04 (g/L)-1s-1 y para CARS catequina, encontrándose un Ic50 de 72.3 mg/L