Resumen Uno de los principales componentes para medición de bioimpedancia son las fuentes de corriente, las cuales son diseñadas principalmente a partir de componentes analógicos discretos. En la actualidad la disminución en los costos de los sistemas digitales y la alta escala de integración permiten plantear soluciones embebidas disminuyendo sustancialmente los componentes electrónicos utilizados. Este articulo presenta el diseño de una fuente de corriente sinusoidal bipolar para aplicaciones de bioimpedancia basada en sistemas realimentados de tiempo discreto, totalmente embebida en un dispositivo de señal mixta PSoC 5LP CY-8C5888AXI-LP096 de Cypress semiconductor montado sobre una tarjeta FreeSoC2 de la empresa SparkFun. La fuente propuesta regula el nivel pico de la corriente bipolar entregada mediante un controlador de tiempo discreto embebido, midiendo el voltaje presente en una resistencia de valor conocido la cual es el único elemento externo a la fuente y que esta serie con la impedancia de carga (Resistencia Shunt), lográndose frecuencias de trabajo de hasta 120 kHz, con resistencias de carga desde 50 Ω a 3 k Ω y corrientes entre 500 LIA y 2 μA, manteniendo una distorsión armónica cercana al 1% para la mayoría del rango de trabajo de la fuente.

Abstract One of the main components for bioimpe-dance measurement is the current sources, which are designed mainly from discrete analog components. Currently, the decrease in the costs of digital systems and the high scale of integration allow us to propose embedded solutions, substantially reducing the electronic components used. This article presents the design of a bipolar sinusoidal current source for bioimpedance applications based on discrete time feedback systems, fully embedded in a mixed signal device PSoC 5LP CY8C5888AXI-LP096 from Cypress semiconductor mounted on a FreeSoC2 card from SparkFun. The proposed source regulates the peak level of the bipolar current delivered by an embedded discrete time controller, measuring the voltage present in a resistor of known value which is the only element external to the source and this series with the load impedance (Resistance Shunt), achieving working frequencies up to 120 kHz, with load resistors from 50 Ω to 3 k Ω and currents between 500 LIA and 2 μA, maintaining a harmonic distortion close to 1% for most of the working range of the source.

ABSTRACT Introduction: Colonic atresia is the least common type of intestinal atresia; however, it must be suspected in patients with partial or complete intestinal obstruction, failure to pass meconium, vomit and abdominal distension. Good prognosis has been described in patients with timely treatment. Case report: This paper reports the case of a newborn patient presenting with vomit, abdominal distension, failure to pass meconium and a rapid progressive clinical deterioration. A colonic atresia was found during exploratory laparotomy, which required a temporary colostomy due to the discrepancy of the proximal and distal calibers. Subsequently, colonic anastomosis was performed using a protective colostomy that was finally closed. This patient had a good post-operative recovery. Conclusion: Colonic atresia must be considered as an important cause of distal intestinal obstruction in pediatric patients and, therefore, it should always be suspected. Ruling out other associated abnormalities is also recommended, as well as performing a rectal biopsy for Hirschsprung's disease to avoid complications.

BACKGROUND Chagas disease (CD), caused by the protozoan Trypanosoma cruzi, is a neglected human disease. It is endemic to the Americas and is estimated to have an economic impact, including lost productivity and disability, of 7 billion dollars per year on average. OBJECTIVES To assess vulnerability to vector-borne transmission of T. cruzi in domiciliary environments within an area undergoing domiciliary vector interruption of T. cruzi in Colombia. METHODS Multi-criteria decision analysis [preference ranking method for enrichment evaluation (PROMETHEE) and geometrical analysis for interactive assistance (GAIA) methods] and spatial statistics were performed on data from a socio-environmental questionnaire and an entomological survey. In the construction of multi-criteria descriptors, decision-making processes and indicators of five determinants of the CD vector pathway were summarily defined, including: (1) house indicator (HI); (2) triatominae indicator (TI); (3) host/reservoir indicator (Ho/RoI); (4) ecotope indicator (EI); and (5) socio-cultural indicator (S-CI). FINDINGS Determination of vulnerability to CD is mostly influenced by TI, with 44.96% of the total weight in the model, while the lowest contribution was from S-CI, with 7.15%. The five indicators comprise 17 indices, and include 78 of the original 104 priority criteria and variables. The PROMETHEE and GAIA methods proved very efficient for prioritisation and quantitative categorisation of socio-environmental determinants and for better determining which criteria should be considered for interrupting the man-T. cruzi-vector relationship in endemic areas of the Americas. Through the analysis of spatial autocorrelation it is clear that there is a spatial dependence in establishing categories of vulnerability, therefore, the effect of neighbors’ setting (border areas) on local values should be incorporated into disease management for establishing programs of surveillance and control of CD via vector. CONCLUSIONS The study model proposed here is flexible and can be adapted to various eco-epidemiological profiles and is suitable for focusing anti-T. cruzi serological surveillance programs in vulnerable human populations.

Resumen El objetivo de este artículo es comparar el rendimiento del control lineal y no lineal para el caso de un motor de corriente continua. La investigación se centra en determinar si las diferencias en el rendimiento entre estos controladores son significativos. La comparación se realizó en el módulo feedback MS150, se incluyen las fases de la estimación de parámetros para los modelos lineales y no lineales, la validación estadística de estos modelos y el diseño e implementación de los controladores. Con el fin de hacer la comparación se definieron dos criterios de rendimiento, basado en el error de seguimiento y en el esfuerzo de control. Estos criterios se aplicaron considerando tres escenarios definidos de acuerdo con el rango en el que se varía el punto de consigna de velocidad. En el primer escenario, la velocidad de referencia se mantuvo constante e igual al valor del punto de operación alrededor de la cual se obtuvo el modelo lineal (60 %). En el segundo y tercer escenario la velocidad de referencia se aumentó, respectivamente, de 40 % al 60 %, y del 20 % a 100 %. De las pruebas experimentales se observó para los escenarios de dos y tres que el error de seguimiento y el esfuerzo de control para el controlador lineal son superiores a las no lineales. Mientras que para el primer escenario, el controlador lineal presenta un error de seguimiento inferior con un esfuerzo de control aproximadamente igual. A partir de este trabajo se concluyó que para las velocidades de referencia que están cerca del punto de operación, el controlador lineal presenta una ventaja significativa sobre controlador no lineal.

Abstract The aim of this article is to compare the performance of linear and non-linear control in the case of a series wound DC motor. The research was focused on determining when the differences in the performance between these controllers are significant. The comparison was made on the MS150 feedback module and it included the phases of parameter estimation for the linear and the non-linear models, the statistical validation of these models and the design and implementation of the controllers. In order to make the comparison there were defined two performance criteria respectively based on the tracking error and on the control effort. These criteria were applied by considering three scenarios defined according to the range in which the velocity set point is varied. In the first scenario, the reference velocity remained constant and equal to the value of the operation point around which the linear model was obtained (60%). In the second and third scenarios the reference velocity was respectively increased from 40 % to 60 % and from 20 % to 100 %. From the experimental tests it was observed for the scenarios two and three that the tracking error and the control effort for the linear controller are superior to the non-linear ones. While for the first scenario, the linear controller presents a lower tracking error with an approximately equal control effort. From this work it was concluded that for reference velocities that are close to the operation point, the linear controller presents a significant advantage over non-linear controller.

ABSTRACT Objectives Present a strategy to determine the baseline in endemic areas in the process of vector interruption for Chagas disease (CHD). Methods A social and environmental questionnaire and an entomological survey evaluated the physical conditions of dwellings, the inhabitants’ knowledge of CHD, the entomological triatomine indicators and the statistical relationship among these variables. Results Colonization and natural infection with Trypanosoma cruzi exist in Rhodnius prolixus, the principal vector of CHD in Colombia. Colonization was related to palm-thatched houses constructed with adobe or wattle and daub. The Panstrongylus geniculatus vector was found to be colonizing. Almost 50% of the surveyed population associated the term CHD with human disease and 37%, with triatomines. Conclusions R. prolixus can be considered to be the principal vector of T. cruzi in domestic environments and the process of interruption is feasible within the prioritized municipality. New studies are needed to verify the existence of wild populations of R. prolixus that could affect future stages of the process and demonstrate whether P. geniculatus is a factor in the transmission of T. cruzi. These scenarios can be made viable by including the inhabitants throughout the process, since they have been highly sensitive in vector detection inside their houses. The study design presented here can be adapted to other endemic areas of the Region of the Americas.

RESUMEN Objetivos Presentar una estrategia para determinar la línea de base en áreas endémicas en el proceso de interrupción vectorial de la enfermedad de Chagas (ECh). Métodos Con un cuestionario socioambiental y una encuesta entomológica, se evaluaron las condiciones físicas de los domicilios, el conocimiento de los habitantes sobre la ECh, los indicadores entomológicos de triatominos y la relación estadística entre estas variables. Resultados Existe colonización e infección natural con Trypanosoma cruzi en Rhodnius prolixus, el principal vector de la ECh en Colombia. La colonización estuvo relacionada con casas de techos de hojas de palma y paredes de adobe o bahareque. Se encontró el vector Panstrongylus geniculatus con hábitos de colonización. Casi 50% de la población encuestada asociaba el término ECh con una enfermedad humana y 37%, con los triatominos. Conclusiones R. prolixus puede considerarse el principal vector de T. cruzi en ambientes domésticos y el proceso de interrupción vectorial es factible dentro del municipio priorizado. Se necesitan nuevos estudios que comprueben la existencia de poblaciones silvestres de R. prolixus que puedan afectar las etapas futuras del proceso y demostrar si hay una participación de P. geniculatus en la dinámica de transmisión de T. cruzi. Los anteriores escenarios pueden ser viabilizados con la inclusión de los habitantes en todo el proceso, ya que han sido altamente sensibles en la detección de vectores dentro de sus casas. El diseño del estudio aquí presentado puede ser adaptado en otras áreas endémicas de la Región de las Américas.