La indagación científica como enfoque pedagógico: estudio sobre las prácticas innovadoras de docentes de ciencia en EM (Región de Valparaíso)

RESUMEN: El presente trabajo refiere los resultados de un estudio cualitativo cuyo objetivo fue describir y comprender las prácticas de seis docentes de ciencia en Educación Secundaria que han logrado transformar su enseñanza, aproximándose a un enfoque indagatorio. El enfoque metodológico empleado fue Grounded Theory, el cual se aplicó a la observación de 54 horas (cr.) de clase. El estudio aporta con información descriptiva y comprensiva sobre las características de las prácticas observadas, así como las condiciones que las permiten y las consecuencias que conllevan. Se finaliza discutiendo el impacto que este estudio tiene sobre la formación inicial y continua de docentes de ciencia de Educación Secundaria. ABSTRACT: This research refers the results of a qualitative study which purpose was to describe and understand the teaching practices of six secondary science teachers who have transformed their teaching practice by applying an inquiry approach. The method used was Grounded Theory applied to the observation of 54 class hours (cr.). This research contributes with descriptive and comprehensive information about characteristics of the observed practices, as well as the conditions that allow them and their consequences. Finally, we discuss the implications that this study has on pre-service and in-service secondary science teacher education

Three Trocars Laparoscopic Resection of Angiomyolipoma of the Liver

Angiomyolipoma of the liver (AML) is an infrequent neoplasm composed of three tissues (adipose, muscle and vessels). In spite of advances in radiology, preoperative correct diagnosis is difficult. Clasically, a conservative management strategy was adopted in patients with asymptomatic tumors less than 5 cm with undoubtful diagnosis. But after publishing some few cases of malignant angiomyolipoma a more radical has been advocated. Laparoscopic resection of liver tumors is becoming a excellent approach for operating on benign liver tumors. Usually is performed using five trocars but in some cases a less invasive technique with three trocars could be used. We present a laparoscopic resection of liver angiomyolipoma in a 65 year-old male using only three trocars and also discuss the optimal management of AML and technical tips of three-trocar technique

Synthesis of Nylon 6/Modified Carbon Black Nanocomposites for Application in Uric Acid Adsorption

High uric acid levels cause different clinic conditions. One of them is hyperuricemia, which leads to kidney damage. A solution for eliminating uric acid in the blood is by hemodialysis, which is performed using nanocomposite membranes. In this work, Nylon 6 nanocomposites were synthesized with modified carbon black (MCB), which were considered candidate materials for hemodialysis membranes. The modification of carbon black was made with citric acid using the variable-frequency ultrasound method. The new MCB was characterized by Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), X-ray diffraction (XRD), transmission electron microscopy (TEM), and dispersion tests. Nylon 6/MCB nanocomposites were processed using the ultrasound-assisted melt-extrusion method to improve the dispersion procedure of the nanoparticles. The Nylon 6/MCB nanocomposites were characterized by FTIR, TGA, and differential scanning calorimetry (DSC). These were assessed for the absorption of toxins and hemocompatibility. MBC and nanocomposites showed excellent uric acid removal (78–82%) and hemocompatibility (1.6–1.8%). These results suggest that Nylon 6/MCB nanocomposites with low loading percentages can be used on a large scale without compatibility problems with blood

Quantum principle of sensing gravitational waves: From the zero-point fluctuations to the cosmological stochastic background of spacetime

We carry out a theoretical investigation on the collective dynamics of an ensemble of correlated atoms, subject to both vacuum fluctuations of spacetime and stochastic gravitational waves. A general approach is taken with the derivation of a quantum master equation capable of describing arbitrary confined nonrelativistic matter systems in an open quantum gravitational environment. It enables us to relate the spectral function for gravitational waves and the distribution function for quantum gravitational fluctuations and to indeed introduce a new spectral function for the zero-point fluctuations of spacetime. The formulation is applied to two-level identical bosonic atoms in an off-resonant high-Q cavity that effectively inhibits undesirable electromagnetic delays, leading to a gravitational transition mechanism through certain quadrupole moment operators. The overall relaxation rate before reaching equilibrium is found to generally scale collectively with the number N of atoms. However, we are also able to identify certain states of which the decay and excitation rates with stochastic gravitational waves and vacuum spacetime fluctuations amplify more significantly with a factor of N². Using such favorable states as a means of measuring both conventional stochastic gravitational waves and novel zero-point spacetime fluctuations, we determine the theoretical lower bounds for the respective spectral functions. Finally, we discuss the implications of our findings on future observations of gravitational waves of a wider spectral window than currently accessible. Especially, the possible sensing of the zero-point fluctuations of spacetime could provide an opportunity to generate initial evidence and further guidance of quantum gravity

Estimación de la radiación solar diaria para la ciudad de Bagua, región Amazonas, Perú

The solar radiation that reaches the earth is the fundamental source of renewable energy in nature, therefore, knowing the local solar radiation is essential for many applications. The objective of this study was to model the behavior of daily solar radiation in the city of Bagua, which allows us to plan and design strategies oriented towards the use of the primary source of renewable energy. For this, the Fernández-Zayas model has been used, which considers the parameters of the monthly  average of the maximum global solar radiation and the length of the solar day. The methodology is of the analytical type and consisted of three phases: The first, data collection and filtering of the meteorological station of the Toribio Rodríguez de Mendoza National University of Amazonas that is located in the study area; in the second, the model was implemented using the MATLAB / GUI interface, obtaining the simulation of solar radiation; and in the third, the model was validated by error goodness statistics and table t. The estimate of daily solar radiation was calculated and discussed. The results obtained are useful for any application of solar energy in the city of Bagua, Amazonas region, Peru.La radiación solar que llega a la tierra, es la fuente de energía renovable fundamental en la naturaleza, por ende, conocer la radiación solar local es esencial para muchas aplicaciones. El objetivo de este estudio fue modelar el comportamiento de la radiación solar diaria en la ciudad de Bagua, el cual nos permita planificar y diseñar estrategias orientadas hacia el aprovechamiento de la fuente primaria de energía renovable. Para ello, se ha empleado el modelo de Fernández-Zayas, el cual considera los parámetros del promedio mensual de la radiación solar global máxima y la longitud del día solar. La metodología es del tipo analítica y consistió en tres fases:La primera, recolección y depuración de datos de la estación meteorológica de la Universidad Nacional Toribio Rodríguez de Mendoza de Amazonas que se encuentra en el área de estudio; en la segunda, se implementó el modelo utilizando la interfaz MATLAB/GUI, obteniendo la simulación de radiación solar; y en la tercera, se validó el modelo mediante los estadísticos de bondad de error y la tabla t. La estimación de la radiación solar diaria se calculó y se discutió. Los resultados obtenidos son útiles para cualquier aplicación de la energía solar en la ciudad de Bagua, región Amazonas, Perú

Fuzzy Control Design for a Class of Nonlinear Network Control System: Helicopter Case Study

This paper presents a fuzzy control approach to a helicopter MIMO nonlinear system, implemented on a Networked Control System, as case study. For this, a hardware-in-the-Loop implementation is developed using several multi-channel A/D Cards, integrated to a computer network system. Variant time delays are considered over Ethernet and CANBUS networks. Fuzzy logic is used to deal with the complexity of the integrated computer network as well as with the dynamics of the system. Two fuzzy logic control systems are coupled for both signals of the helicopter case study: yaw and pitch. Both these tend to concentrate around desired references, considering variant time delays

Playas

En el presente trabajo se plantea las actividades que se ha realizado en este semestre, la importancia del derecho ambiental y junto con los derechos humanos; la aplicación en la práctica de cada uno de los aprendizajes obtenidos durante las clases a lo largo de toda la carrera, como en una estructura bien desarrollada y en una planeación acompañada de los maestros, compañeros de trabajos y los encargados de este Proyecto de Aplicación Profesional, donde se puede apreciar que se logró el objetivo de alcanzar la justicia, siendo la presentación de dos recursos y la investigación respecto del tema de las playas certificadas, donde lo que quería es demostrar que se deben de garantizar los derechos humanos en todo momento.ITESO, A.C

Legislative framework for sediment management in the United States

[EN] Sediment erosion is a serious issue, with approximately 75 billion tons of soil is eroded annually around the world (Pimentel and Kounang, 1998). Although erosion is a natural process, it can accelerate due to human activity and land use changes. Increasing soil erosion beyond its natural threshold can result in significant environmental degradation and decreased economic productivity. Implementing sediment management laws and practices is critical to significantly decrease soil erosion and preserve environmental resources. In the United States, there is a comprehensive system of laws and regulations at national, state, county, and city level that govern erosion and sediment control. The laws and voluntary incentives outlined in our paper have significantly reduced the negative impacts of sediment carried in urban and storm-generated runoff, have reduced chemical and biological pollutants in sediment transported in aquatic ecosystems, and have improved the air quality in several cities with air pollution problems. Having a multi-faceted approach to monitoring erosion and improving soil management is important for a healthy, productive environment and economy.[ES] La erosión de sedimentos es un problema serio, con aproximadamente 75.000 millones de toneladas de suelo erosionadas anualmente en todo el mundo (Pimentel y Kounang, 1998). Aunque la erosión es un proceso natural, ésta puede acelerarse debido a la actividad humana y a los cambios en el uso de la tierra. El incremento de la erosión del suelo más allá de su umbral natural puede resultar en una degradación ambiental significativa y una disminución de la productividad económica. La implementación de leyes y prácticas de gestión de sedimentos es fundamental para disminuir significativamente la erosión del suelo y preservar los recursos ambientales. En los Estados Unidos, existe un sistema integral de leyes y regulaciones a nivel nacional, estatal, del condado y de ciudad que gobiernan la erosión y el control de sedimentos. Las leyes y los incentivos voluntarios descritos en nuestro trabajo han reducido significativamente los impactos negativos de los sedimentos transportados en las escorrentías urbanas y rurales, han reducido los contaminantes químicos y biológicos en los sedimentos transportados hacia los ecosistemas acuáticos y han mejorado la calidad del aire en varias ciudades con problemas de contaminación atmosférica. 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Fecha de acceso 21 Abril, 2017.U.S. Department of Agriculture. 2017b. Natural Resource Conservation Service. Recuperado de https://www.nrcs.usda.gov/wps/portal/nrcs/site/national/home/. Fecha de acceso 21 Marzo, 2017.U.S. Department of Agriculture. 2017c. Incentive Programs and Assistance for Producers. Natural Resource Conservation Service. Recuperado de https://www.nrcs.usda.gov/wps/portal/nrcs/detail/national/climatechange/resources/?cid=stelprdb1043608. Fecha de acceso 23 Marzo, 2017.U.S. Department of Agriculture. 2017d. National Water Quality Initiative. Natural Resource Conservation Service. Recuperado de https://www.nrcs.usda.gov/wps/portal/nrcs/detail/national/water/?cid=stelprdb1047761. Fecha de acceso 30 Abril, 2017.U.S. Department of Agriculture. 2017e. eDirective. Electronic Directives. Natural Resource Conservation Service. Recuperado de https://directives.sc.egov.usda.gov/Default.aspx. Fecha de acceso 23 Abril, 2017.U.S. Department of the Interior. 2004. 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