Systemic intervention for computer-supported collaborative learning

This paper presents a systemic intervention approach as a means to overcome the methodological challenges involved in research into computer-supported collaborative learning applied to the promotion of mathematical problem-solving (CSCL-MPS) skills in schools. These challenges include how to develop an integrated analysis of several aspects of the learning process; and how to reflect on learning purposes, the context of application and participants' identities. The focus of systemic intervention is on processes for thinking through whose views and what issues and values should be considered pertinent in an analysis. Systemic intervention also advocates mixing methods from different traditions to address the purposes of multiple stakeholders. Consequently, a design for CSCL-MPS research is presented that includes several methods. This methodological design is used to analyse and reflect upon both a CSCL-MPS project with Colombian schools, and the identities of the participants in that project

Seismic site classification from the horizontal-to-vertical response spectral ratios: use of the Spanish strong-motion database

Normally, the average of the horizontal-to-vertical (H/V) ratios of the 5% damped response spectra of ground motions is used to classify the site of strong-motion stations. In these cases, only the three-orthogonal as-recorded acceleration components are used in the analysis, and all the vector compositions that can generate a different response for each period oscillator are excluded. In this study, the Spanish strong-motion database was used to classify the sites of accelerometric stations based on the predominant periods through the average horizontal-to-vertical spectral ratios (HVSR) of recorded ground motions. Moreover, the directionality effects using the vector composition of the horizontal components of ground motions were also considered in the estimations of H/V ratios. This consideration is a relevant novelty compared to the traditional H/V ratios methods. Only earthquakes with magnitudes above 3.5 and hypocentral distances below 200 km were selected, which resulted in 692 ground-motion records, corresponding to 86 stations, from events in the period between 1993 and 2017. After the analysis, a predominant-period site classification was assigned to each station. On the whole, the obtained mean and standard deviation values of the spectral ratios are comparable to those shown by other researchers. Therefore, the advantages of the proposed procedure, which takes the directionality effects into account, can be summarized as follows: (a) The obtained information is richer and gives enables more sophisticated and realistic analyses on the basis of percentiles and (b) it is easier to detect anomalous stations, sites, and/or accelerograms. Moreover, the method eliminates the effect of directionality as a contributor to epistemic uncertainty.Peer ReviewedPostprint (published version

Construcción de un densímetro operado magnéticamente

Se diseñó y construyó un densímetro operado magnéticamente, el cual permite determinar la densidad de una solución con precisión hasta la quinta cifra decimal. En el diseno se tuvo en cuenta la posibilidad de poder armar y desarmar fácilmente las diferentes piezas que constituyen el densímetro, con el objeto de cambiar la bobina principal y asi aumentar el rango de las densidades que se pueden medir. La calibración del densímetro se realizó mediante anillos de platino y soluciones de cloruro de sodio. Igualmente, se diseñó, construyó y montó un sistema para el control de temperatura, el cual no presentó desviaciones mayores de 10,006°C a 25°C

Do directionality effects influence expected damage? A case study of the 2017 central Mexico earthquake

We analyze the case of a building that collapsed in a multifamily complex of Tlalpan borough in Mexico City during the 19 September 2017 Central Mexico earthquake. Despite having similar materials and similar structural and geometric properties, this was the only building that collapsed in the complex. A structural analysis of the building and a study of the soils’ predominant periods indicated that resonance effects, if any, would not be significant. However, phenomena related to the anomalous performance of buildings in dense urban areas such as geological soil, soil–structure interaction, and soil–city interaction effects were also investigated. A detailed analysis of the directionality of seismic actions recorded at nearby accelerometric stations and of the azimuths of sound and damaged buildings indicates that directionality effects were responsible for the collapse of the building. Subsequently, a set of 58, two-component acceleration records of the earthquake was used to perform a thorough directionality analysis. The results were then compared with the foreseen uniform hazard response spectra and the design spectra in the city. Seismic actions in the city due to this earthquake were stronger than those corresponding to the uniform hazard response spectra. In addition, although design spectra have been significantly improved in the new 2017 Mexican seismic regulations, they were exceeded in 11 of 58 analyzed spectra. In 4 of these 11 cases, the design spectra were exceeded due to directionality effects. These results confirm the necessity of considering directionality effects in damage assessments, strong-motion prediction equations, and design regulations.Peer ReviewedPostprint (author's final draft

Un enfoque alternativo para tomar en cuenta el efecto de la direccionalidad sísmica

Recent researches have proven the importance of considering the seismic directionality effect. The performance of buildings subjected to earthquakes depends on its orientation respect to the seismic actions applied. This type of calculation is computed using the nonlinear dynamic analysis (NLDA) and rotating the acceleration horizontal components onto all non-redundant angles, which entails a high computational cost. This paper presents an alternative approach to consider the directionality effect. The method is based on the nonlinear static analysis (NLSA) and on the energy balance between the capacity curves and the response spectra of the rotated seismic actions. This approach was applied to a 4-story steel frame building 3D-model with ground motions records from Mexico City. A high variability in the building performance is observed due to the incidence angle of the seismic action; the proposed method would allow considering this variation in the structural analysis, in an easy way, demanding less calculation time and providing results compatible with those obtained through the NLDA.Peer ReviewedPostprint (published version

Extrapolación a dilución infinita del volumen molar aparente de sales de amonio cuaternario en soluciones acuosas diluidas

Se midieron las densidades a 25,000 ± 0,006°C de soluciones acuosas diluidas de los yoduros de bencil trimetll amonio y dimetil dibencil amonio, e mpleando un densímetro de flotación magnética. Se calcularon los volúmenes molares aparentes 0v S^ obtuvieron volúmenes molares parciales a dilución infinita, extrapolando los valores de 0 ^ mediante la ecuación de Redlich y Meyer yj—°y + S^y^c-Fb^c,sin el término bvc. El cambio progresivo de un grupo metilo por un grupo bencilo en el yoduro de tetrametll amonio produce un incremento en el volumen parcial molar a dilución infinita de 64,4 ml/mol para las sales estudiadas

Actividad antinflamatoria de extractos y fracciones obtenidas de cálices de Physalis peruviana L.

Introduction. Cape gooseberry calyces (Physalis peruviana) have been used in folk medicine for their medicinal properties including anticancer, antimycobacterial, antipyretic, diuretic, immunomodulatory and antiinflammatory properties.Objective. The antiinflammatory effect was evaluated for extracts and fractions obtained from Physalis peruviana calyces in a mice model of acute inflammation. The fractions responsible for antiinflammatory activity were extracted for possible identification.Materials and Methods. The Physalis peruviana calyces were extracted by percolation with organic solvents. The primary hydroalcoholic fraction was purified by column chromatography. The antiinflammatory effect of extracts and fractions was evaluated using the 12-Otetradecanoylphorbol-13-acetate-induced mouse model of ear edema.Results. Thirty-eight secondary fractions were obtained by column chromatography of primary hydroalcoholic fraction. Six fractions, evaluated in 12-O-tetradecanoylphorbol-13-acetateinduced inflammation assay, showed significant antiinflammatory activity (p<0.05). The major fraction, Pp-D28-LF, showed a significant dose-dependent response at doses over 250 μg/ear.Conclusion. The antiinflammatory activity attributed to Physalis peruviana calyces was confirmed and validated its use in folk medicine. Fractions responsible for the antiinflammatory action were identified and seem promising for phytomedicinal development. Further studies are needed to isolate and identify the active constituents of these fractions as well as to ascertain the mechanisms involved in the antiinflammatory effect.Introducción. Los cálices de la uchuva, Physalis peruviana, son ampliamente utilizados en la medicina popular por sus propiedades como anticancerígeno, antimicobacterial, antipirético, diurético, immunomodulador y antinflamatorio.Objetivo. Evaluar el efecto antinflamatorio de extractos y fracciones obtenidas de los cálices de Physalis peruviana en un modelo de inflamación aguda en ratón, procurando identificar las fracciones responsables de dicha actividad.Materiales y métodos. Los cálices de Physalis peruviana fueron extraídos por percolación con solventes orgánicos. La fracción primaria hidroalcohólica se purificó mediante cromatografía en columna. La actividad antinflamatoria de los extractos y fracciones se evaluó utilizando el modelo murino de edema auricular inducido por 13-acetato de 12-tetradecanoilforbol. Resultados. Se obtuvieron 38 fracciones secundarias en la cromatografía en columna de la fracción primaria hidroalcohólica, de las cuales seis fueron evaluadas en el modelo inflamatorio, mostrando actividad significativa (p<0,05). La fracción mayoritaria identificada como Pp-D28-LF presentó una respuesta dosis dependiente con significativa inhibición del edema en dosis superiores a 250 μg/oreja (p<0,05).Conclusión. Este estudio confirma la actividad antinflamatoria atribuida a los cálices de Physalis peruviana y también valida su uso en la medicina popular. Se identificaron las principales fracciones responsables de la actividad antinflamatoria, las cuales parecen ser promisorias para el desarrollo de fitopreparados. Se requieren estudios posteriores para aislar e identificar los compuestos responsables de la actividad y también para investigar el mecanismo involucrado en el efecto antinflamatorio observado

A Semiautomated Classification System for Producing Service Directories in Social and Health Care (DESDE-AND): Maturity Assessment Study

Background: DESDE-LTC (Description and Evaluation of Services and DirectoriEs for Long-Term Care) is an international classification system that allows standardized coding and comparisons between different territories and care sectors, such as health and social care, in defined geographic areas. We adapted DESDE-LTC into a computer tool (DESDE-AND) for compiling a directory of care services in Andalucia, Spain. Objective: The aim of this study was to evaluate the maturity of DESDE-AND. A secondary objective of this study is to show the practicality of a new combined set of standard evaluation tools for measuring the maturity of health technology products. Methods: A system for semiautomated coding of service provision has been co-designed. A panel of 23 domain experts and a group of 68 end users participated in its maturity assessment that included its technology readiness level (TRL), usability, validity, adoption (Adoption Impact Ladder [AIL]), and overall degree of maturity [implementation maturity model [IMM]). We piloted the prototype in an urban environment (Seville, Spain). Results: The prototype was demonstrated in an operational environment (TRL 7). Sixty-eight different care services were coded, generating fact sheets for each service and its geolocation map. The observed agreement was 90%, with moderate reliability. The tool was partially adopted by the regional government of Andalucia (Spain), reaching a level 5 in adoption (AIL) and a level 4 in maturity (IMM) and is ready for full implementation. Conclusions: DESDE-AND is a usable and manageable system for coding and compiling service directories and it can be used as a core module of decision support systems to guide planning in complex cross-sectoral areas such as combined social and health care

Peces del bajo río Sogamoso, cuenca del Magdalena, Colombia: diversidad, uso y conservación

La red fluvial del río Magdalena es impresionante, no solo por la densidad de cauces por área y los gradientes en la pendiente, sino también por la capacidad de producción de agua, sedimentos y del régimen hidrológico particular. Dos veces al año y estacionalmente, las lluvias bañan los suelos. Parte del agua se infiltra y otra fluye hacía los cauces donde se concentra y fluye unidireccionalmente “río abajo”, conformando una banda transportadora que permite el flujo de sedimentos y la dispersión de la biota acuática. El río Sogamoso se considera el afluente más importante en la margen derecha del río Magdalena. Realmente lo es, tanto por el área de drenaje, el caudal y la geomorfología particular, como por la alta carga de sedimentos que arrastra hacía su zona baja, una planicie amplia que estacionalmente se inunda y conecta a la ciénaga El Llanito, favoreciendo la dispersión de los peces durante cada temporada seca. La cantidad de material que arrastraba el río era tal que aún recuerdo la imagen de mi piel cubierta por una fina capa de sedimentos, luego de haber estado haciendo un arrastre con chinchorro para colectar peces por allá en el año 1998 en el sector de Puerto Cayumba.Fil: Escobar L., María D.. Instituto de Investigación de Recursos Biológicos Alexander von Humboldt; ColombiaFil: Méndez López, Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico - Tucumán. Unidad Ejecutora Lillo; Argentina. Instituto de Investigación de Recursos Biológicos Alexander von Humboldt; ColombiaFil: Pinzón Quiñónez, Luis E.. Instituto de Investigación de Recursos Biológicos Alexander von Humboldt; ColombiaFil: Arias Mañosca, Maribel. Instituto de Investigación de Recursos Biológicos Alexander von Humboldt; ColombiaFil: Serrano Gómez, Marlon. Ecopetrol S.A; ColombiaFil: Lasso, Carlos A.. Instituto de Investigación de Recursos Biológicos Alexander von Humboldt; Colombi