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  1. Mortalidad por defectos del tubo neural en México, 1980-1997

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    Ramírez-Espitia José A

    2003-01-01

    Full Text Available OBJETIVO: Describir la mortalidad en México por defectos del tubo neural, durante el periodo 1980-1997. MATERIAL Y MÉTODOS: Las tasas anuales de mortalidad estatales y nacionales, por defectos del tubo neural, se calcularon por 10 000 nacidos vivos. La tendencia temporal fue evaluada por el porcentaje de cambio anual obtenido mediante un modelo de regresión de Poisson. Se calculó la razón de mortalidad, tomando la media nacional como referencia. Las tasas y las razones se representaron gráficamente en mapas. RESULTADOS: Durante el periodo la tasa bruta de mortalidad por defectos del tubo neural fue de 5.8 por 10 000 nacidos vivos. La anencefalia fue el tipo de defecto más frecuente (37.7%, seguida de la espina bífida sin hidrocefalia (31.6%. La tendencia nacional de la mortalidad por defectos del tubo neural fue ascendente entre 1980 y 1990 (porcentaje de cambio anual 7.5 IC 95% 6.5, 8.6 y descendente entre 1990-1997 (porcentaje de cambio anual -2.3 IC 95% -3.6, -0.9. CONCLUSIONES: Las altas tasas de mortalidad por defectos del tubo neural fueron debidas principalmente a la elevada frecuencia de las anencefalias. El incremento observado parece no ser sólo atribuible a cuestiones puramente diagnósticas o de mejora en los registros. La influencia de factores asociados a estos defectos, como determinados polimorfismos genéticos, la deficiencia de ácido fólico, la obesidad materna, la exposición laboral a plaguicidas y la pobreza deberán evaluarse mediante estudios específicos.

  2. Frecuencia y algunos factores de riesgo de mortalidad en el estado de Hidalgo, México, por defectos de cierre del tubo neural

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    Muñoz-Juárez Sergio

    2002-01-01

    Full Text Available Objetivo. Calcular el riesgo de muerte fetal secundaria a defectos del cierre del tubo neural y estimar factores asociados con este tipo de muertes en el estado de Hidalgo. Material y métodos. La información analizada en el año 2000 fue obtenida de los certificados de muerte fetal del periodo 1990-1995 en el estado de Hidalgo. Se utilizó un diseño de mortalidad proporcional, considerado como una variante del diseño de casos y controles. Los casos fueron aquellas muertes fetales secundarias a defectos del tubo neural y los controles las muertes fetales por otros motivos. Se utilizó ji cuadrada de Pearson para estimar las diferencias entre los casos y controles. Para el riesgo crudo de morir por defectos de cierre del tubo neural se empleó la razón de momios, y para el riesgo ajustado se usó la regresión logística no condicional. Resultados. Se analizaron 3 673 certificados de muerte fetal, identificándose 8.06% de muertes por defectos del tubo neural; el resto lo constituyeron muertes por otras causas. Se encontró como variables asociadas con la muerte fetal por defectos del tubo neural a los fetos que pesaron menos de 2 500 gramos (RM 5.0, IC 95% 3.6, 6.7, a los productos del sexo femenino (RM 1.7, IC 95% 1.3, 2.3 y a las muertes ocurridas en el periodo fetal tardío (RM 5.5 IC 95% 3.8, 8.1. Conclusiones. Los resultados indican que el riesgo de muerte fetal debida a defectos del tubo neural es mayor en productos de bajo peso, en los del sexo femenino y los que ocurren en el periodo fetal tardío.

  3. Defectos del tubo neural y del ácido fólico: recorrido histórico de una intervención preventiva altamente efectiva

    OpenAIRE

    Adriana Ordoñez Vásquez; Fernando Suarez-Obando

    2015-01-01

    Este artículo describe de forma comprehensiva parte del devenir histórico que han tenido, el conocimiento médico de los defectos del tubo neural (DTN) y el descubrimiento de la vitamina B9 o ácido fólico, así como algunos de los acontecimientos investigativos relevantes que a través de varios siglos definieron las relaciones entre la comprensión de la embriología del sistema nervioso central, el descubrimiento de la vitamina, la correlación de...

  4. Dificultades en los métodos de estudio de exposiciones ambientales y defectos del tubo neural

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    Borja-Aburto Víctor Hugo

    1999-01-01

    Full Text Available Objetivo. Discutir las actitudes en la evaluación de las exposiciones ambientales como factores de riesgo para defectos de riesgo del tubo neural, al tiempo que se presentan los principales factores estudiados hasta la fecha. Resultados. Las exposiciones ambientales se citan muy a menudo como causa de malformaciones congénitas; sin embargo, ha sido difícil establecer esta asociación en los estudios de poblaciones humanas, debido a problemas en su diseño y conducción. Lo anterior es particularmente marcado en el caso del estudio de los defectos del cierre del tubo neural (DTN, que es una de las principales malformaciones y que incluye anencefalia, espina bífida y encefalocele, y su asociación con exposiciones ambientales. Las dificultades en los métodos surgen de: a la medida de frecuencia para realizar comparaciones espacio-temporales; b la clasificación y heterogeneidad de las malformaciones; c la consideración de los factores relacionados con la madre, el padre y el producto, de manera conjunta, y d la evaluación de las exposiciones ambientales. Conclusiones. Hipotéticamente las exposiciones ambientales tanto del padre como de la madre pueden producir daño genético antes y/o después de la concepción por la acción directa sobre el embrión o sobre el complejo fetoplacentario, de tal manera que en la evaluación de exposiciones ambientales: a deben tomarse en cuenta las exposiciones maternas y paternas; b debe considerarse el periodo crítico de exposición, esto es, tres meses anteriores a la concepción para el padre y un mes alrededor de la concepción para la madre; c en la medida de lo posible, la evaluación de la exposición deberá ser cuantitativa, evitando clasificar a los grupos únicamente como expuestos y no expuestos, y d es recomendable emplear marcadores biológicos de exposición siempre que sea posible, así como utilizar marcadores biológicos que permitan clasificar a la población en grupos con distinta

  5. Mortalidad por defectos del tubo neural en México, 1980-1997 Mortality due to neural tube defects in Mexico, 1980-1997

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    José A Ramírez-Espitia

    2003-10-01

    Full Text Available OBJETIVO: Describir la mortalidad en México por defectos del tubo neural, durante el periodo 1980-1997. MATERIAL Y MÉTODOS: Las tasas anuales de mortalidad estatales y nacionales, por defectos del tubo neural, se calcularon por 10 000 nacidos vivos. La tendencia temporal fue evaluada por el porcentaje de cambio anual obtenido mediante un modelo de regresión de Poisson. Se calculó la razón de mortalidad, tomando la media nacional como referencia. Las tasas y las razones se representaron gráficamente en mapas. RESULTADOS: Durante el periodo la tasa bruta de mortalidad por defectos del tubo neural fue de 5.8 por 10 000 nacidos vivos. La anencefalia fue el tipo de defecto más frecuente (37.7%, seguida de la espina bífida sin hidrocefalia (31.6%. La tendencia nacional de la mortalidad por defectos del tubo neural fue ascendente entre 1980 y 1990 (porcentaje de cambio anual 7.5 IC 95% 6.5, 8.6 y descendente entre 1990-1997 (porcentaje de cambio anual -2.3 IC 95% -3.6, -0.9. CONCLUSIONES: Las altas tasas de mortalidad por defectos del tubo neural fueron debidas principalmente a la elevada frecuencia de las anencefalias. El incremento observado parece no ser sólo atribuible a cuestiones puramente diagnósticas o de mejora en los registros. La influencia de factores asociados a estos defectos, como determinados polimorfismos genéticos, la deficiencia de ácido fólico, la obesidad materna, la exposición laboral a plaguicidas y la pobreza deberán evaluarse mediante estudios específicos.OBJECTIVE: To describe the mortality due to neural tube defects (NTD in Mexico for the 1980-1997 period. MATERIAL AND METHODS: The annual NTD mortality rates per 10000 liveborn infants were calculated by state and for the country. The time trend was evaluated with the annual percent change (APC obtained using a Poisson regression model. The NTD mortality ratio was calculated using the average national rate as reference. NTD mortality rates and ratios were

  6. Frecuencia y algunos factores de riesgo de mortalidad en el estado de Hidalgo, México, por defectos de cierre del tubo neural

    OpenAIRE

    Muñoz-Juárez Sergio; Vargas-Flores Humberto; Hernández-Prado Bernardo; López-Ríos Olga; Ortiz-Espinosa Rosa María

    2002-01-01

    Objetivo. Calcular el riesgo de muerte fetal secundaria a defectos del cierre del tubo neural y estimar factores asociados con este tipo de muertes en el estado de Hidalgo. Material y métodos. La información analizada en el año 2000 fue obtenida de los certificados de muerte fetal del periodo 1990-1995 en el estado de Hidalgo. Se utilizó un diseño de mortalidad proporcional, considerado como una variante del diseño de casos y controles. Los casos fueron aquellas muertes fetales secundarias a ...

  7. Frecuencia de los defectos del tubo neural en Asturias: impacto del diagnóstico prenatal Prevalence of neural tube defects in Asturias (Spain: impact of prenatal diagnosis

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    Enrique García López

    2009-12-01

    Full Text Available Objetivo Describir la frecuencia de defectos del tubo neural (DTN -anencefalia, espina bífida y encefalocele-en Asturias, su evolución temporal y el impacto del diagnóstico prenatal. Métodos: Se estudiaron los casos de DTN en nacidos y abortos inducidos durante el período 1990-2004, utilizando la base de datos del Registro de Defectos Congénitos de Asturias, de base poblacional. Se calcularon las tasas de prevalencia total y al nacimiento. Resultados: La prevalencia total de DTN fue de 12,2 casos por 10.000 nacidos (5,9 anencefalias, 5,0 espinas bífidas y 1,3 encefaloceles y mostró una tendencia ligeramente descendente, con un descenso significativo de la espina bífida, mientras que las cifras de anencefalia y encefalocele se mantuvieron estables. Finalizaron en aborto inducido tras el diagnóstico prenatal el 88% de los casos (anencefalia 96,7%; espina bífida 80%; encefalocele 84,6%, lo que determinó una prevalencia al nacimiento muy baja (1,4 DTN por 10.000 nacidos. Conclusiones: En Asturias, en los últimos 15 años se ha producido un descenso selectivo en la prevalencia total de espina bífida de causa no aclarada. La prevención secundaria, mediante los programas de diagnóstico prenatal y la consiguiente interrupción del embarazo, fue el motivo del marcado descenso de la frecuencia en los nacidos; la simple recomendación de suplementación periconcepcional con ácido fólico no parece haber logrado el efecto buscado.Objective: To describe the frequency and prevalence trend for neural tube defects (NTD (anencephaly, spina bifida and encephalocele in Asturias (Spain, as well as the impact of prenatal diagnosis programs. Methods: All cases of NTD in births and induced abortions were studied, using data from the Registry of Congenital Defects of Asturias for 1990-2004. Total and birth prevalence rates were calculated. Results: The prevalence of NTD for 1990-2004 was 12.2 per 10,000 births (5.9 anencephaly, 5.0 spina bifida and 1

  8. Efeito da fortificação alimentar com ácido fólico na prevalência de defeitos do tubo neural Efecto de la fortificación alimentaria con ácido fólico en la prevalencia de defectos del tubo neural Effects of folic acid fortification on the prevalence of neural tube defects

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    Sâmya Silva Pacheco

    2009-08-01

    Full Text Available OBJETIVO:Analisar o efeito de alimentos fortificados com ácido fólico na prevalência de defeitos de fechamento do tubo neural entre nascidos vivos. MÉTODOS: Estudo longitudinal de nascidos vivos do município de Recife (PE entre 2000 e 2006. Os dados pesquisados foram obtidos do Sistema Nacional de Informações de Nascidos Vivos. Os defeitos de fechamento do tubo neural foram definidos de acordo com o Código Internacional de Doenças-10ª Revisão: anencefalia, encefalocele e espinha bífida. Compararam-se as prevalências nos períodos anterior (2000-2004 e posterior (2005-2006 ao período mandatório à fortificação. Analisou-se a tendência temporal das prevalências trimestrais de defeitos do fechamento do tubo neural pelos testes de Mann-Kendall e Sen's Slope. RESULTADOS: Não se identificou tendência de redução na ocorrência do desfecho (Teste de Mann-Kendall; p= 0,270; Sen's Slope =-0,008 no período estudado. Não houve diferença estatisticamente significativa entre as prevalências de defeitos do fechamento do tubo neural nos períodos anterior e posterior à fortificação dos alimentos com acido fólico de acordo com as características maternas. CONCLUSÕES: Embora não tenha sido observada redução dos defeitos do fechamento do tubo neural após o período mandatório de fortificação de alimentos com ácido fólico, os resultados encontrados não permitem descartar o seu benefício na prevenção desta malformação. São necessários estudos avaliando maior período e considerando o nível de consumo dos produtos fortificados pelas mulheres em idade fértil.OBJETIVO:Analizar el efecto de alimentos fortificados con ácido fólico en la prevalencia de defectos del cierre del tubo neural entre nacidos vivos. MÉTODOS: Estudio longitudinal de nacidos vivos del municipio de Recife (Noreste de Brasil, entre 2000 y 2006. Los datos pesquisados fueron obtenidos del Sistema Nacional de Informaciones de Nacidos Vivos. Los

  9. Dificultades en los métodos de estudio de exposiciones ambientales y defectos del tubo neural Methodological challenges to assess environmental exposures related to neural tube defects

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    Víctor Hugo Borja-Aburto

    1999-11-01

    Full Text Available Objetivo. Discutir las actitudes en la evaluación de las exposiciones ambientales como factores de riesgo para defectos de riesgo del tubo neural, al tiempo que se presentan los principales factores estudiados hasta la fecha. Resultados. Las exposiciones ambientales se citan muy a menudo como causa de malformaciones congénitas; sin embargo, ha sido difícil establecer esta asociación en los estudios de poblaciones humanas, debido a problemas en su diseño y conducción. Lo anterior es particularmente marcado en el caso del estudio de los defectos del cierre del tubo neural (DTN, que es una de las principales malformaciones y que incluye anencefalia, espina bífida y encefalocele, y su asociación con exposiciones ambientales. Las dificultades en los métodos surgen de: a la medida de frecuencia para realizar comparaciones espacio-temporales; b la clasificación y heterogeneidad de las malformaciones; c la consideración de los factores relacionados con la madre, el padre y el producto, de manera conjunta, y d la evaluación de las exposiciones ambientales. Conclusiones. Hipotéticamente las exposiciones ambientales tanto del padre como de la madre pueden producir daño genético antes y/o después de la concepción por la acción directa sobre el embrión o sobre el complejo fetoplacentario, de tal manera que en la evaluación de exposiciones ambientales: a deben tomarse en cuenta las exposiciones maternas y paternas; b debe considerarse el periodo crítico de exposición, esto es, tres meses anteriores a la concepción para el padre y un mes alrededor de la concepción para la madre; c en la medida de lo posible, la evaluación de la exposición deberá ser cuantitativa, evitando clasificar a los grupos únicamente como expuestos y no expuestos, y d es recomendable emplear marcadores biológicos de exposición siempre que sea posible, así como utilizar marcadores biológicos que permitan clasificar a la población en grupos con distinta

  10. Frecuencia y algunos factores de riesgo de mortalidad en el estado de Hidalgo, México, por defectos de cierre del tubo neural Mortality due to neural tube defects and risk factors in Hidalgo, Mexico

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    Sergio Muñoz-Juárez

    2002-09-01

    Full Text Available Objetivo. Calcular el riesgo de muerte fetal secundaria a defectos del cierre del tubo neural y estimar factores asociados con este tipo de muertes en el estado de Hidalgo. Material y métodos. La información analizada en el año 2000 fue obtenida de los certificados de muerte fetal del periodo 1990-1995 en el estado de Hidalgo. Se utilizó un diseño de mortalidad proporcional, considerado como una variante del diseño de casos y controles. Los casos fueron aquellas muertes fetales secundarias a defectos del tubo neural y los controles las muertes fetales por otros motivos. Se utilizó ji cuadrada de Pearson para estimar las diferencias entre los casos y controles. Para el riesgo crudo de morir por defectos de cierre del tubo neural se empleó la razón de momios, y para el riesgo ajustado se usó la regresión logística no condicional. Resultados. Se analizaron 3 673 certificados de muerte fetal, identificándose 8.06% de muertes por defectos del tubo neural; el resto lo constituyeron muertes por otras causas. Se encontró como variables asociadas con la muerte fetal por defectos del tubo neural a los fetos que pesaron menos de 2 500 gramos (RM 5.0, IC 95% 3.6, 6.7, a los productos del sexo femenino (RM 1.7, IC 95% 1.3, 2.3 y a las muertes ocurridas en el periodo fetal tardío (RM 5.5 IC 95% 3.8, 8.1. Conclusiones. Los resultados indican que el riesgo de muerte fetal debida a defectos del tubo neural es mayor en productos de bajo peso, en los del sexo femenino y los que ocurren en el periodo fetal tardío.Objective. To calculate the risk of fetal death due to neural tube defects and estimate associated factors in the state of Hidalgo, Mexico. Material and Methods. Data were abstracted from death certificates registered during 1990-1995 in the state of Hidalgo, Mexico. The design was a proportional mortality study, which is considered as a variant of the case control design. Cases were deaths with any type of neural tube defect, and controls

  11. Disminución de la incidencia de defectos de cierre del tubo neural en el Hospital Universitario de Neiva: posible efecto de la promoción del consumo de ácido fólico

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    Henry Ostos

    2000-03-01

    Full Text Available Los defectos del tubo neural (DTN son defectos de nacimiento, del cerebro o la médula espinal, los cuales llevan a la muerte o a la discapacidad. Las causas de los DTN son desconocidas. Se piensa que ocurren por una interacción de factores genéticos y ambientales. En 1997, se observó un significativo aumento en la incidencia de defectos del tubo neural en el Hospital Universitario de Neiva (p=0,035, respecto al atio anterior. El primer esfuerzo de control consistió en promover el consumo de ácido fólico siguiendo las recomendaciones universales de suplementación y fortificación (CDC Folic Acid Resource Guide. En este estudio se evaluó la incidencia de los DTN durante 1998, como posible indicador del impacto de las medidas tomadas. Se identificaron los nacidos con DTN, los nacidos con síndrome de Down o con labio o paladar hendido, la proporción de abortos y la de nacidos muertos. La tasa de DTN disminuyó en forma signiticativa (p=0,024 respecto a 1997 y su diferencia con la tasa de Latinoamérica no fue significativa (p=0,526. Se concluyó que la incidencia fue menor en 1998 y regresó a la tasa esperada para la región. Aunque se desconoce la causa del descenso, es posible que sea el resultado de la divulgación de los beneficios de una buena nutrición materna, la suplementación pregestacional con ácido fólico, la fortificación de la harina de trigo, o una sumatoria de todas las medidas. Se recomienda desarrollar un estudio de actitudes y prácticas sobre el uso de ácido fólico en la población de mujeres de Neiva en edad fértil y establecer un protocolo de vigilancia activa de los DTN.

  12. Como Lo Hago Yo: Anomalías del Tubo Neural en Guatemala — Mielomeningocele Unidad de Espina Bífida e Hidrocefalia

    Science.gov (United States)

    Manucci, Graciela; von Quednow, Enzo

    2014-01-01

    En Guatemala nacen por añ 786 niños con defectos de tubo neural. Operamos 65 a 70 niños con mielomenigocele por año. Tenemos equipo multidisciplinario. Recomendamos parto por cesárea. Infección antes de la cirugía es un problema mayor. Derivación tardía es un problema. Disecamos la plaqueta con la técnica clásica. Suturamos la plaqueta para restituir la forma de la médula. Corpectomía en casos de cifósis. Hidrocefalía: Operamos el 80% de los niños. Chiari II: Operamos basados en los síntomas, primero nos aseguramos que la válvula funciona bien. Médula anclada: Operamos basados en los síntomas. PMID:24791216

  13. Peru's national folic acid fortification program and its effect on neural tube defects in Lima Programa nacional del Perú de fortificación con ácido fólico y su efecto sobre los defectos del tubo neural en Lima

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    Daniel J. Ricks

    2012-12-01

    Full Text Available OBJECTIVE: To evaluate the impact of Peru's national folic acid fortification program on folic acid content in wheat flour, and the effect on birth prevalence of neural tube defects (NTDs in Lima, and to compare the program's legislative requirements with international standards. METHODS: Bread was sampled from six sites across Peru and tested for folic acid. Data were obtained from the largest obstetric hospital in Lima on the prevalence of births (live and still with NTDs during both the pre-fortification period (2004-2005 and post-fortification years (2007-2008. RESULTS: Folic acid content in the sampled bread met national legislative requirements but was less than one-half of the level recommended for Peru by the World Health Organization (WHO (2.6 mg/kg wheat flour. Birth prevalence of NTDs was 18.4/10 000 in the pre-fortification period and 20.0/10 000 during post-fortification years. Relative risk for NTDs after fortification was 1.02 (95% confidence interval 0.77-1.35, P = 0.90. CONCLUSIONS: Peruvian legislative requirements for folic acid fortification are below international (WHO recommendations; birth prevalence of NTDs in Lima is higher than international benchmarks; and no decrease in NTDs following fortification of flour with folic acid (according to Peruvian national standards was observed. As increasing the level of folic acid in flour remains the most sustainable way of preventing NTDs, it is recommended that Peru increase its folic acid fortification requirements to meet those recommended by WHO (2.6 mg/kg.OBJETIVO: Evaluar la repercusión que el programa nacional del Perú de fortificación con ácido fólico tiene en el contenido de ácido fólico de la harina de trigo y en la prevalencia de nacimientos de niños con defectos del tubo neural en Lima, así como comparar los requisitos legislativos del programa con las normas internacionales. MÉTODOS: Se hizo un muestreo del pan en seis zonas de Perú y se analizó su

  14. Prevalência e distribuição espacial de defeitos do tubo neural no Estado de São Paulo, Brasil, antes e após a fortificação de farinhas com ácido fólico Prevalencia y distribución espacial de defectos del tubo neural en el Estado de São Paulo, Brasil, antes y después del enriquecimiento de harinas con ácido fólico Prevalence and spatial distribution of neural tube defects in São Paulo State, Brazil, before and after folic acid flour fortification

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    Elizabeth Fujimori

    2013-01-01

    Full Text Available Estudo transversal que analisou prevalência e distribuição espacial de defeitos do tubo neural, antes e após a fortificação das farinhas de trigo e milho com ácido fólico no Estado de São Paulo, Brasil, com uso do Sistema de Informações sobre Nascidos Vivos (SINASC. São apresentadas prevalências segundo características maternas por meio de odds ratio (OR e intervalos de 95% de confiança (IC95%. Para análise temporal e espacial, foram utilizados, respectivamente, regressão polinomial e mapas com suavização bayesiana empírica. A prevalência diminuiu 35%, de 0,57 para 0,37 por mil nascidos vivos após a fortificação (OR = 0,65; IC95%: 0,59-0,72. Verificou-se redução para mulheres de todas as idades (exceto Estudio transversal que analizó la prevalencia y distribución espacial de defectos del tubo neural, antes y después del enriquecimiento de las harinas de trigo y maíz con ácido fólico en el Estado de Sao Paulo, Brasil, con el uso del Sistema de Información sobre Nacidos Vivos (SINASC. Se presentaron prevalencias, según características maternas, mediante odds ratio (OR e intervalos de un 95% de confianza (IC95%. Para un análisis temporal y espacial, fueron utilizados, respectivamente, regresión polinomial y mapas con suavizamiento bayesiano empírico. La prevalencia disminuyó un 35%, de 0,57 a 0,37 por mil nacidos vivos tras el enriquecimiento (OR = 0,65; IC95%: 0,59-0,72. Se verificó la reducción en mujeres de todas las edades (excepto This cross-sectional study analyzed the prevalence and spatial distribution of neural tube defects before and after folic acid flour fortification. The study used the Information System on Live Births (SINASC and presented prevalence rates according to maternal characteristics with odds ratios (OR and 95% confidence intervals (95%CI. Polynomial regression was used in time trend analysis and empirical Bayesian smoothed maps for spatial analysis. Total prevalence of neural tube

  15. Física por un tubo. Mide la velocidad del sonido en el aire y diviértete con los tubos sonoros

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    Ana Cros

    2011-01-01

    Full Text Available En este trabajo damos las claves para diseñar un conjunto de tubos sonoros de PVC que permiten realizar una ejecución musical en grupo con la participación de un gran número de personas sin cultura musical previa. Proponemos además la utilización de los tubos para el estudio cuantitativo de los fenómenos físicos involucrados en la generación del sonido con instrumentos de viento. Se describe la utilización de los tubos sonoros, en combinación con un ordenador y un programa de análisis de sonido, para el análisis de ondas estacionarias y la determinación de la velocidad de propagación del sonido en el aire mediante distintos procedimientos.

  16. Mecanismo de falla de los tubos del sobrecalentador de una caldera acuotubular

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    John Jairo Coronado Marín

    2007-09-01

    Full Text Available En este artículo se investigaron las causas de las fallas presentadas por fisuración longitudinal a partir de la superficie externa en los tubos del sobrecalentador de una caldera acuotubular. La superficie externa de los tubos presentó una capa de color blanco-rojizo que presentó cadenas parafínicas: C-H, grupos funcionales: C-O, N-H y compuestos de azufre, esta capa frágil impide la transferencia de calor, causando un aumento de temperatura del tubo. La falla se presentó por termofluencia debido al sobrecalentamiento de larga duración, la microestructura del tubo de acero en el lado externo presentó: crecimiento de grano, globulización de la cemen-tita y fisuras intergranulares que producen pérdidas de las propiedades mecánicas del acero. Las observaciones anteriores evidencian un deterioro de la microestructura facilitado por un material que no está en capacidad de operar usando exclusivamente bagazo como combustible.

  17. Impacto de la fortificación de alimentos con ácido fólico en los defectos del tubo neural en Costa Rica Impact of the fortification of food with folic acid on neural tube defects in Costa Rica

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    María de la Paz Barboza Argüello

    2011-07-01

    Full Text Available OBJETIVO: Evaluar el impacto de la fortificación de alimentos con ácido fólico en las tendencias de las prevalencias de los defectos del tubo neural (DTN y la tasa de mortalidad infantil (TMI por este trastorno en Costa Rica. MÉTODOS: Se analizaron los datos de vigilancia del Centro de Registro de Enfermedades Congénitas y el Centro Centroamericano de Población. Se consideraron defectos del tubo neural la anencefalia, la espina bífida y el encefalocele. Se examinaron las tendencias durante 1987-2009, así como las diferencias de tasas (intervalo de confianza [IC] 95% de prevalencia y mortalidad antes de la fortificación de alimentos con ácido fólico y hasta 12 años después de su implementación. Se determinó el aporte de la fortificación al descenso en la TMI general. RESULTADOS: En 1987-1997, previo al período de fortificación de alimentos con ácido fólico, la prevalencia de DTN fue de 12/10 000 nacidos (IC95%: 11,1-12,8, mientras que en 2009 fue de 5,1/10 000 nacidos (3,3-6,5. La TMI por DTN en 1997 fue de 0,64/1 000 nacimientos (46-0,82 y en 2009 de 0,19/1 000 (0,09-0,3. La TMI por DTN y su prevalencia disminuyeron en forma significativa, 71% y 58% respectivamente (P OBJECTIVE: Evaluate the impact of the fortification of food with folic acid on prevalence trends for neural tube defects (NTD and the infant mortality rate (IMR associated with this disorder in Costa Rica. METHODS: The surveillance data from the Congenital Disease Registry Center and the Central American Population Center were analyzed. The neural tube defects considered were anencephaly, spina bifida, and encephalocele. The trends from 1987-2009, as well as the differences in prevalence and mortality rates prior to and up to 12 years after food fortification with folic acid, were examined (95% confidence interval [CI]. The contribution of fortification to the decrease in the overall IMR was determined. RESULTS: During 1987-1997, prior to the period of food

  18. DESCRIPCIÓN MORFOLÓGICA DEL TUBO DIGESTIVO DE JUVENILES DE RUBIO Salminus affinis (PISCES: CHARACIDAE

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    VJ Atencio

    2008-09-01

    Full Text Available El objetivo del estudio fue la descripción del tubo digestivo de juveniles de Rubio Salminus affinis. Se analizaron cinco juveniles con 23,6±2,6 cm de longitud total y 142,8±62,5 g de peso. Se realizó descripción topográfica y morfológica de los órganos y cortes histológicos con tinción H-E. El esófago es un órgano tubular corto de pared gruesa que representa el 7,8% de la longitud total del tubo digestivo, presenta pliegues internos que ofrecen gran capacidad de distensión permitiendo el paso de presas de gran tamaño. El estómago es una bolsa asimétrica en forma de “Y”, grande y musculosa, amplio en la porción anterior y estrecho hacia el fondo; el número de ciegos pilóricos varió entre 13 y 23 pudiendo ser monotubulares y ramificados. El intestino, con tres asas, se extiende desde el esfínter pilórico hasta el ano. Histológicamente el tubo digestivo está formado por cuatro capas: mucosa, submucosa, muscular y serosa; el epitelio de revestimiento del esófago es estratificado plano no queratinizado con células caliciformes, cambiando a simple cilíndrico mucosecretor llegando al estómago; en el estómago se encuentra epitelio simple cilíndrico mucosecretor y los ciegos pilóricos e intestino son revestidos por epitelio simple cilíndrico con células caliciformes. Tanto el valor promedio del coeficiente intestinal (0,58, como la pared distensible del estómago sugieren que el Rubio tiene un tubo digestivo propio de carnívoro y sus características histológicas presentan similitud con la mayoría de vertebrados superiores.

  19. Folato, vitamina B12 e ferritina sérica e defeitos do tubo neural Folate, vitamin B12, serum ferritin and defects of the neural tube

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    Gizele Thame

    1998-09-01

    Full Text Available Objetivo: verificar os níveis de folatos, vitamina B12 e ferritina em pacientes cujos fetos apresentaram defeitos de tubo neural (DTN. O folato sangüíneo e a vitamina B12 atuam como cofatores para as enzimas envolvidas na biossíntese do DNA. A interrupção deste processo pode impedir o fechamento do tubo neural. A suplementação vitamínica contendo folato pode reduzir as taxas de ocorrência de defeitos de tubo neural, embora exista a preocupação de que esta prevenção possa mascarar a deficiência de vitamina B12. Métodos: dosagens de vitamina B12 e ferritina pelo método de enzimaimunoensaio com micropartículas e a dosagens de ácido fólico pelo método de captura iônica (IMx ABBOTT. Resultados: a porcentagem de gestantes com deficiência de vitamina B12 (níveis séricos Purpose: to determine folate, vitamin B12 and ferritin levels in patients whose fetuses presented neural-tube defects (NTD. Blood folate and vitamin B12 act as cofactors of enzymes involved in DNA biosynthesis. Interruption of this process may block neural-tube closing. Vitamin supplementation with folate may reduce occurrence rates and recurrence of NTD, although there is concern about the fact that this prevention may mask vitamin B12 deficiency. Methods: vitamin B12 and ferritin determinations by enzyme immunoassay with microparticles and folic acid determination using the ion capture method (IMx ABBOTT. Results: the percentage of pregnant women with vitamin B12 deficirncy (serum levels < 150 pg/ml was 11.8%. There was no case of folate deficiency (serum levels < 3.0 ng/ml and prevalence of pregnant women with iron store deficiency was 47.1% (serum levels < ng/mg. Conclusions: occording to the results obtained in this study (prevalence of 11.8% of vitamin B12 and 0% of folate deficient pregnant women we suggest that supplementation should be administered after serum vitamin B12 determination.

  20. TUBO system

    International Nuclear Information System (INIS)

    Barbosa, H.J.C.; Guerreiro, J.N.C.; Toledo, E.M.

    1980-01-01

    Proceedings recently incorporated to TUBO system like the seismic analysis and the stress verification acccording to ASME-Boiler Rule and Pressure Vessel Code-section III are presented. The seismic analysis comprehend the consideration of uniform motion of the support, its multiple excitation, and the attainment of the spectral response for both cases. The module for stress verification uses stresses resulting fromthe combination of the loads specified by the user, in the automatic verification of permissible stresses for the pipings class 1 and 2, based on criteria NB-3650 and NC-3650 of ASME. The implementation of these proceedings in the TUBO system are discussed and a numerical example that covers the different phases of a stress analysis in a piping is presented [pt

  1. Brain tissue aspiration neural tube defect Aspiração de tecido cerebral em casos de defeitos de fechamento do tubo neural

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    Luiz Cesar Peres

    2005-09-01

    Full Text Available The study aimed to find out how frequent is brain tissue aspiration and if brain tissue heterotopia could be found in the lung of human neural tube defect cases. Histological sections of each lobe of both lungs of 22 fetuses and newborn with neural tube defect were immunostained for glial fibrillary acidic protein (GFAP. There were 15 (68.2% females and 7 (31.8% males. Age ranged from 18 to 40 weeks of gestation (mean= 31.8. Ten (45.5% were stillborn, the same newborn, and 2 (9.1% were abortuses. Diagnosis were: craniorrhachischisis (9 cases, 40.9%, anencephaly (8 cases, 36,4%, ruptured occipital encephalocele and rachischisis (2 cases, 9.1% each, and early amniotic band disruption sequence (1 case, 4.5%. Only one case (4.5% exhibited GFAP positive cells inside bronchioles and alveoli admixed to epithelial amniotic squames. No heterotopic tissue was observed in the lung interstitium. We concluded that aspiration of brain tissue from the amniotic fluid in neural tube defect cases may happen but it is infrequent and heterotopia was not observed.O objetivo do estudo foi identificar qual a freqüência de aspiração de tecido cerebral e a existência de heterotopia nos pulmões de casos humanos de defeito de fechamento do tubo neural através da reação imuno-histoquímica para proteína fibrilar glial ácida (GFAP em cortes histológicos de todos os lobos de ambos os pulmões de 22 casos de fetos e neonatos com defeito de fechamento do tubo neural. Havia 15 casos femininos (68,2% e 7 masculinos (31,8%, com idade gestacional variando de 18 a 40 semanas (média= 31,8, sendo natimortos e neomortos 10 (45,5% cada e 2 (9,1% abortos. Os diagnósticos foram: Craniorraquisquise (9 casos, 40,9%, anencefalia (8 casos, 36,4%, encefalocele occipital rota e raquisquise (2 casos, 9,1% e 1 (4,5%caso de seqüência de disruptura amniótica precoce. Somente 1 caso (4,5% apresentou células positivas dentro de bronquíolos e alvéolos em meio a células epiteliais

  2. Disostose espôndilo-costal associada a defeitos de fechamento do tubo neural Spondylocostal dysostosis associated with neural tube defects

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    Rafael Fabiano M. Rosa

    2009-09-01

    Full Text Available OBJETIVO: Salientar a relação dos defeitos de fechamento do tubo neural com a disostose espôndilo-costal (DEC por meio da descrição de três pacientes. DESCRIÇÃO DOS CASOS: Paciente 1: menina branca, 22 meses, nascida com mielomeningocele lombar. Na avaliação, apresentava hipotonia, baixa estatura, dolicocefalia, fendas palpebrais oblíquas para cima, pregas epicânticas e tronco curto com tórax assimétrico. A avaliação radiográfica revelou hemivértebras múltiplas, vértebras em borboleta e fusão e ausência de algumas costelas. Paciente 2: menina branca, 22 meses, com moderado atraso do desenvolvimento neuropsicomotor, baixa estatura, olhos profundos, pregas epicânticas, pescoço e tronco curtos com assimetria do tórax, abdome protruso, hemangioma plano na altura da transição lombossacra e fosseta sacral profunda no dorso. A avaliação radiográfica identificou hemivértebras, fusão incompleta de vértebras e vértebras em borboleta, malformações de costelas e espinha bífida oculta em L5/S1. Paciente 3: menina branca, 9 dias de vida, com fendas palpebrais oblíquas para cima, ponte nasal alargada, orelhas baixo implantadas e rotadas posteriormente, tronco curto, tórax assimétrico e meningocele tóraco-lombar. A avaliação radiográfica evidenciou hemivértebras, malformação e ausência de algumas costelas e agenesia diafragmática à esquerda. A tomografia computadorizada de encéfalo mostrou estenose de aqueduto. COMENTÁRIOS: Vários defeitos de fechamento do tubo neural, de espinha bífida oculta a grandes mielomeningoceles, são observados em pacientes com DEC, indicando que tais pacientes devem ser cuidadosamente avaliados quanto à possível presença desses defeitos.OBJECTIVE: To highlight the relationship between neural tube defects and spondylocostal dysostosis (SCD through the description of three patients. CASES DESCRIPTION: Patient 1: white girl, 22 months old, born with a lumbar meningomyelocele. At

  3. Análisis del comportamiento elasto-plástico de grietas internas presurizadas en uniones soldadas de tubos de acero bajo carbono

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    Martín Julián Fernández Cueto

    2011-01-01

    Full Text Available Se analizó el comportamiento elasto-plástico de áreas con grietas internas planas presurizadas. El análisis se efectuó desde el metal base (uniones soldadas de tubos de acero bajo carbono sometidos a presión interna pasando por la zona afectada por el calor hasta el metal depositado. Se usó el programa comercial ANSYS 8.0 [MR] para la simulación en tres dimensiones de modelos geométricos de tubos con grietas internas presurizadas. Se consideró el endurecimiento cinemático y las propiedades reales del material para cada región, mediante elementos finitos con condiciones no lineales de deformación. Se determinaron las trayectorias de fractura y se obtuvieron expresiones que permiten calcular la presión en la grieta y en el tubo. Esto conduce a la fractura de la zona agrietada.

  4. Texto y figuras preparatorios del Capítulo 9 (Tomo I) de la Histología del Sistema Nervioso de Cajal: TUBOS NERVIOSOS.

    OpenAIRE

    Freire, Miguel

    2007-01-01

    TUBOS NERVIOSOS. Tubo nervioso medular periférico (forma, volumen, estructura, etc.). ─ Tubo nervioso medular de los centros. ─ Fibras de Remak. ─ Asociación de las fibras nerviosas para constituir los nervios, etc.[Ver: Freire, Miguel. Metodología usada en la presente edición. Metodología e historia de la edición en la correspondencia de Cajal. https://digital.csic.es/handle/10261/150245

  5. Influencia de la soldadura sobre la rotura por tensiones en tubos de acero inoxidable austenitico del tipo 18-11NB(TP347

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    Gutiérrez de Saiz-Solabarria, S.

    2000-06-01

    Full Text Available This work has been undertaken to study the stress cracking failure in various 18Cr11Ni [TP347 (18-11Nb, TP 321 (18-11 Ti, TP304 (18-11 and TP316 (18-11-2] types austenitic stainless steel tubes. The material used was produced hot-rolling at 76,2 mm φ (3"φ x 2,54 mm (1/10" thickness. The study was carried out at 593ºC and applied stress of 50 Ton/in2.

    Se estudia el efecto de la soldadura sobre la rotura por tensiones en tubos de acero inoxidable austenítico estabilizado con Nb o Ti de los tipos 18-11Nb (TP 347 y 18-11Ti (TP 321 así como sin estabilizar del tipo 18-11 (TP 304 y con Mo del tipo 18-11-2 (TP 316. Los tubos, en todos los casos, son de dimensiones 76,2 mm (3” φ x 2,54 mm (1/10” de espesor y la tensión aplicada (σ de 10 Ton/in2, para una temperatura de servicio de 593ºC.

  6. Defeitos de fechamento do tubo neural e fatores associados em recém-nascidos vivos e natimortos Neural tube defects and associated factors among liveborn and stillborn infants

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    Marcos J.B. Aguiar

    2003-04-01

    Full Text Available OBJETIVOS: avaliar a prevalência e fatores associados aos defeitos de fechamento do tubo neural em recém-nascidos vivos e natimortos, na maternidade do Hospital das Clínicas da UFMG, entre 01/08/1990 e 31/07/2000. MÉTODOS: trata-se de trabalho descritivo, baseado em banco de dados, seguindo normas do Estudo Colaborativo Latino-Americano de Malformações Congênitas (ECLAMC. São confeccionadas fichas dos recém-nascidos vivos e natimortos com anomalias congênitas, com descrição morfológica, resultados de necropsia, exames complementares, história familiar, social, da gravidez, e outros dados clínicos. Cada recém-nascido vivo malformado dá origem a um controle, do mesmo sexo, sem malformações. Os recém-nascidos vivos e natimortos com defeitos de fechamento do tubo neural, no período, foram classificados de acordo com o defeito apresentado e com a presença ou ausência de outros defeitos associados. Foram comparados sexo, peso, idade e paridade materna com os demais recém-nascidos vivos e natimortos do período. A análise estatística utilizou o programa Epi-Info 6.0. RESULTADOS: a prevalência dos defeitos de fechamento do tubo neural foi de 4,73:1.000 partos (89:18.807, tendo sido maior entre os natimortos (23,7:1.000 que entre os recém-nascidos vivos (4,16:1.000, p 3 gestações, p=0,007. Não houve associação com sexo ou idade materna. Entre os natimortos não houve associação com sexo, peso, paridade ou idade materna. Os defeitos de fechamento do tubo neural mais freqüentes foram mielomeningocele (47,2%, anencefalia (26,9% e encefalocele (16,9%. Os defeitos se encontravam como anomalia isolada em 71,1% dos recém-nascidos vivos e 38,5% dos natimortos; faziam parte de uma síndrome em 9,2% dos recém-nascidos vivos e em 7,7% dos natimortos. CONCLUSÃO: a prevalência dos defeitos de fechamento do tubo neural foi maior do que a descrita na literatura internacional e na literatura latino-americana.OBJECTIVES: to

  7. Utilización del Tisuacryl® en la anastomosis del esófago con otros segmentos del tubo digestivo Use of Tisuacryl® in esophagus anastomosis with other segments of the digestive tube

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    Rosalba Roque González

    2006-06-01

    Full Text Available Las dehiscencias y fístulas de las anastomosis del esófago con segmentos pediculados del tubo digestivo son complicaciones frecuentes en la cirugía del esófago. En diversas estadísticas recientes, nacionales y extranjeras, se ha registrado una incidencia de hasta el 40 %. Este hecho, unido a las ventajas reportadas en la utilización de los adhesivos sintéticos del tipo del Tisuacryl®, hace interesante realizar un estudio clínico para extender el uso del producto al reforzamiento de las suturas en la anastomosis del esófago con otros segmentos del tubo digestivo, con el fin de prevenir las dehiscencias. Se realizó un ensayo clínico de fase II, prospectivo, controlado, aleatorizado, multicéntrico, a simple ciegas, que se extendió desde enero de 1998 hasta febrero de 2005. En él se incluyeron pacientes que ingresaron en los hospitales «Calixto García» y «Miguel Enríquez» con el diagnóstico de enfermedades esofágicas. Se logró la introducción en el país de una nueva aplicación para el adhesivo tisular Tisuacryl® y se demostró que la utilización del producto es una opción significativamente más ventajosa que el procedimiento convencional sólo con sutura, ya que se obtuvo una eficacia del 93 % en el grupo experimental respecto al 64 % en el grupo control. Uno y otro grupo eran homogéneos respecto a las variables de control. El tratamiento con Tisuacryl® disminuyó la frecuencia de aparición de fístulas esofágicas y no se reportaron eventos adversos en relación con la aplicación del producto.The dehiscences and fistulae of esophagus anastomosis with pedicular segments of the digestive tube are frequent complications in esophagus surgery. In various recent national and foreign statistics, an incidence of even 40 % has been registered. This fact, together with the advantages reported on the use of synthetic adhesives like Tisuacryl® made us to take an interest in conducting a clinical study to extend the use of

  8. Evaluación del método del tubo para concentrar plaquetas felinas: estudio celular Evaluation of the tube method for concentrating feline platelets: cellular study

    OpenAIRE

    RF Silva; CMF Rezende; FO Paes-Leme; JU Carmona

    2011-01-01

    El objetivo de este estudio fue evaluar un método manual para concentrar plaquetas de gato y, en consecuencia, producir concentrados autólogos de plaquetas (APCs) o plasma rico en plaquetas (PRP) con propósitos clínicos y experimentales. El PRP se obtuvo por la extracción de sangre venosa en tubos con solución ACD que fueron centrifugados a 85 g durante 6 minutos. Para los recuentos celulares de sangre entera y PRP, se encontraron diferencias estadísticamente significativas (P < 0,01) entre l...

  9. La erupción y el tubo volcánico del Volcán Corona (Lanzarote, Islas Canarias

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    Láinez, A.

    2003-12-01

    -erosivo de la isla. La datación de la erupción del Volcán Corona, aparentemente el evento volcánico anterior en Lanzarote a las erupciones históricas, ha dado una edad media ponderada 40Ar/39Ar de 21 f 6,5 ka. Esta edad concuerda con las observaciones geológicas, particularmente las circunstancias de formación del tubo volcánico de 7,6 km de longitud y hasta 25 m de diámetro que se formó en las primeras fases de la erupción. El último tramo de 1,6 km está sumergido, finalizando a una profundidad de > 80 m. Nuestra interpretación es que el tubo volcánico activo no pudo alcanzar esa profundidad circulando por un medio subacuático, sino que fluyó por una plataforma costera al menos 1,6 km más extensa y al menos 80 m más baja que la costa actual, circunstancia que sólo ha podido darse en coincidencia con un pronunciado descenso del nivel marino en un máximo glacial, con toda probabilidad el último, hace unos 20 ka. La subsiguiente transgresión inundó el tubo hasta el nivel actual. La edad de la erupción queda pues limitada por las edades radioisotópicas en 21 f 6,5 ka y, concordantemente, por el máximo descenso del nivel marino, registrado entre unos 18 y 21 ka. El estudio de la erupción del Corona establece hitos importantes en la historia volcánica de la isla de Lanzarote y aporta evidencia significativa de los cambios del nivel marino ocurridos en las Canarias en relación con las glaciaciones.

  10. Prevalência de defeitos de fechamento de tubo neural no Vale do Paraíba, São Paulo Prevalence of neural tube defects in Vale do Paraíba, São Paulo, Brazil

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    Luiz Fernando C. Nascimento

    2008-12-01

    Full Text Available OBJETIVO: Estimar a prevalência de defeitos de fechamento do tubo neural no Vale do Paraíba paulista e identificar possíveis fatores maternos e neonatais associados a tais defeitos. MÉTODOS: Realizou-se um estudo transversal com dados secundários obtidos na Secretaria Estadual da Saúde referentes aos nascimentos ocorridos em 2004 no Vale do Paraíba paulista, que compreende 35 municípios e conta com população de 2 milhões de habitantes. Anencefalia, encefalocele e espina bífida (mielocele e mielomeningocele foram considerados defeitos de fechamento do tubo neural. As variáveis maternas foram: idade, escolaridade, cor da pele, número de consultas no pré-natal, número de filhos vivos e relato de óbito fetal prévio. As variáveis relativas ao recém-nascido foram: peso, idade gestacional e escore de Apgar. Realizou-se comparação das médias por meio do teste t de Student e obtiveram-se os valores das razões de chance com intervalos de confiança de 95%. RESULTADOS: Foram analisados 33.653 nascidos vivos. Trinta e oito recém-nascidos com o defeito foram encontrados (1,13/1.000 nascidos vivos, sendo 23 casos de espina bífida. Houve associação com baixo peso ao nascimento, prematuridade e menores escores de Apgar de cinco minutos. CONCLUSÕES: A prevalência desta anomalia foi inferior à de outros estudos nacionais e sua presença esteve associada ao baixo peso, à prematuridade e à baixa vitalidade ao nascer.OBJECTIVE: To estimate the prevalence of neural tube defects in Vale do Paraíba, São Paulo, Brazil, and to identify possible maternal and neonatal variables associated with these defects. METHODS: This cross-sectional study used secondary records of the Health Department of São Paulo State related live births during 2004 in Vale do Paraíba, São Paulo, Brazil. This region has 35 cities and 2 million inhabitants. Anencephaly, encephalocele and spina bifida (myelocele and myelomeningocele were considered as neural tube

  11. Tubo-ovarian actinomycosis.

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    Shroff C

    1981-01-01

    Full Text Available Actinomycotic infection of the female genital tract is rare. Actinomycosis is a chronic suppurative granulomatous infection that is characterized by formation of abscesses, multiple draining sinuses and appearance of tangled mycelial masses or granules in the discharges and tissue sections. 2 cases of tubo-ovarian actinomycosis are reported. The 1st case presented clinical with gastrointestinal symptoms and a ventral scar hernia following an operation for a non-healing abdominal wound 6 months earlier. The 2nd case sought medical attention for backache and leucorrhea of 4 years′ duration. Exploratory laparotomy in the 1st case revealed tubo-ovarian masses; the vermiform appendix was not traceable. The uterine cavity in the 2nd case harbored a wooden stick. Direct extension from established ileocacal actinomycosis was believed to involve the female genital adnexae in the past. Association of tubo-ovarian actinomycosis with the presence of a foreign body in the female genital tract has been reported sporadically in the literature, yet an increase in the incidence may be expected because of the frequent use of intrauterine contraceptive devices in recent times. It is suggested that in women presenting clinically with vague abdominal symptoms, backache and discharge, actinomycosis should be considered and ruled out with the help of cytologic and proper microbial culture methods. Once the diagnosis is established, the infection can be treated with good results with penicillin.

  12. Determinación de la susceptibilidad a drogas de primera línea en aislamientos de mycobacterium tuberculosis por la técnica del tubo indicador de crecimiento micobacteriano

    OpenAIRE

    Sierra Parada, Claudia Rocío; Sánchez Morales, Édgar Alberto; Henao Riveros, Sandra Consuelo; Saavedra Rodríguez, Alfredo

    2010-01-01

    Antecedentes. La aparición de aislamientos de Mycobacterium tuberculosis resistentes a los medicamentos ha hecho que se busquen métodos más rápidos y confiables para la determinación de la susceptibilidad a las drogas antituberculosas. Objetivo. Determinación de la susceptibilidad a drogas antituberculosas de primera línea en aislamientos de M. tuberculosis utilizando el método del tubo indicador de crecimiento micobacteriano (MGIT). Material y métodos. Se estudiaron 49 aislamientos...

  13. DETERMINACIÓN DE LA SUSCEPTIBILIDAD A DROGAS DE PRIMERA LÍNEA EN AISLAMIENTOS DE MYCOBACTERIUM TUBERCULOSIS POR LA TÉCNICA DEL TUBO INDICADOR DE CRECIMIENTO MICOBACTERIANO

    OpenAIRE

    Claudia Rocío Sierra Parada; Édgar Alberto Sánchez Morales; Sandra Consuelo Henao Riveros; Alfredo Saavedra Rodríguez

    2008-01-01

    Antecedentes. La aparición de aislamientos de Mycobacterium tuberculosis resistentes a los medicamentos ha hecho que se busquen métodos más rápidos y confiables para la determinación de la susceptibilidad a las drogas antituberculosas. Objetivo. Determinación de la susceptibilidad a drogas antituberculosas de primera línea en aislamientos de M. tuberculosis utilizando el método del tubo indicador de crecimiento micobacteriano (MGIT). Material y métodos. Se estudiaron 49 aislamientos de...

  14. Utilizacion de tubo laríngeo S® en pacientes sometidas a cirugía laparoscópica ginecológica, Clínica Del Prado, Medellín, Colombia

    Directory of Open Access Journals (Sweden)

    Juliana María Mendoza Villa

    2008-02-01

    Full Text Available

    INTRODUCCIÓN: se ha utilizado con éxito el Tubo Laríngeo Succión (TLS en muchos procedimientos quirúrgicos, incluyendo cirugías con riesgo mayor de broncoaspiración. Con el objetivo de corroborar la eficacia de este dispositivo para prevenir la broncoaspiración diseñamos un estudio descriptivo, observacional y prospectivo utilizando dicho tubo en pacientes sometidas a cirugía laparoscópica ginecológica.

    POBLACIÓN Y METODOLOGÍA: se utilizó el TLS en pacientes ASA I - II sometidas a cirugía ginecológica laparoscópica que cumplieron los criterios de inclusión. Se realizó fibrobroncoscopia por el tubo de drenaje y por el tubo ventilatorio del dispositivo luego de la inducción del neumoperitoneo y al finalizar la cirugía, para determinar la presencia o no de secreción de origen gástrico.

    RESULTADOS: un total de 110 pacientes ingresaron al estudio. No se presentó ningún caso de regurgitación o de broncoaspiración. El éxito en la inserción del dispositivo fue de 94,5% (104 de 110.

    CONCLUSIONES: en el presente estudio encontramos que el

  15. Predição do comportamento térmico de tubos compósitos através de redes neurais Prediction of thermal behavior of composite tubes using neural networks

    Directory of Open Access Journals (Sweden)

    Sheila Contant

    2004-12-01

    Full Text Available Compósitos poliméricos (plásticos reforçados são materiais formados a partir de um reforço (fase descontínua, normalmente uma fibra e uma matriz polimérica. Esse tipo de material apresenta várias vantagens em relação aos materiais convencionais de engenharia. Entre os métodos de fabricação de compósitos poliméricos está o filament winding (filamento contínuo ou enrolamento filamentar, um processo empregado na fabricação de sólidos de revolução, como tubos e tanques. Neste trabalho, redes neurais artificiais, uma ferramenta computacional inspirada no funcionamento do cérebro humano, foram aplicadas ao processo de filament winding para predição do comportamento térmico de tubos compósitos durante a etapa de cura. Informações sobre o comportamento térmico das peças compósitas podem auxiliar na seleção do ciclo de cura, que é um dos desafios na obtenção de peças de qualidade e a um baixo custo. As redes neurais foram treinadas com dados obtidos através do modelo Lee-Springer. A metodologia foi validada com resultados experimentais da literatura.Polymeric composites or reinforced plastics are materials made with a polymer matrix and a reinforcement. These materials have many advantages when compared to conventional engineering materials. Among the manufacturing methods for composite parts from continuous fiber reinforcement is the filament winding, often used to fabricate closed-surface structures such as tubes and tanks. In this work artificial neural networks, a computational tool inspired in the human brain, were applied in the filament winding process to predict the thermal behavior of composite tubes during the curing step. Information about the thermal behavior of composite parts may help in the selection of the appropriate cure cycle, which is one of the challenges in obtaining quality parts at low cost. Networks were trained with data obtained with the Lee-Springer model. The methodology was validated

  16. Endotracheal and upper airways suctioning: changes in newborns’ physiological parameters Aspiración del tubo endotraqueal y de las vías aéreas superiores: alteraciones en los parámetros fisiológicos en recién nacidos Aspiração do tubo orotraqueal e de vias aéreas superiores: alterações nos parâmetros fisiológicos em recém-nascidos

    Directory of Open Access Journals (Sweden)

    Andréa Lopes Barbosa

    2011-12-01

    Full Text Available This study investigated which physiological parameters change when endotracheal and upper airway suctioning is performed immediately before, immediately after and five minutes after this procedure is performed in newborns hospitalized in a Neonatal Intensive Care Unit (NICU. This is a quantitative and longitudinal study, before and after type, performed in the NICU of a public institution in the city of Fortaleza, CE, Brazil. The sample was composed of 104 newborns using oxigenotherapy and who needed endotracheal and upper airway suctioning. The results showed significant alterations in respiratory and heart rates (pSe objetivó investigar cuales son los parámetros fisiológicos que se alteran en la ejecución de la aspiración del tubo endotraqueal (TOT y de las vías aéreas superiores (VAS, comparándolos inmediatamente antes, inmediatamente después y cinco minutos después de la realización del referido procedimiento. Se trata de un estudio cuantitativo, longitudinal, del tipo antes y después, realizado en una Unidad de Terapia Intensiva Neonatal (UTIN de una institución pública en Fortaleza, CE, Brasil. La muestra constó de 104 recién nacidos que usaban oxigenoterapia, y que necesitaron de aspiración del tubo endotraqueal y de las vías aéreas superiores. Los resultados mostraron, alteraciones significativas (pObjetivou-se investigar quais são os parâmetros fisiológicos que se alteram na execução da aspiração do tubo orotraqueal (TOT e das vias aéreas superiores (VAS, comparando-os imediatamente antes, imediatamente depois e cinco minutos após a realização do referido procedimento. Trata-se de estudo quantitativo, longitudinal, do tipo antes e depois, realizado em Unidade de Terapia Intensiva Neonatal (Utin de uma instituição pública em Fortaleza, CE, Brasil. A amostra constou de 104 recém-nascidos em uso de oxigenoterapia, e que necessitaram de aspiração do tubo orotraqueal e das vias aéreas superiores. Os

  17. Efeitos da pressão limite (25 cmH2O e mínima de “selo” do balonete de tubos traqueais sobre a mucosa traqueal do cão Efectos de la presión limite (25 cmH2O y mínima de “sello” del balón de tubos traquéales sobre la mucosa traqueal del can Effects of tracheal tube cuff limit pressure (25 cmH2O and “seal” pressure on tracheal mucosa of dogs

    Directory of Open Access Journals (Sweden)

    Emanuel Celice Castilho

    2003-12-01

    Full Text Available JUSTIFICATIVA E OBJETIVOS: As lesões da mucosa traqueal em contato com o balonete do tubo traqueal são proporcionais à pressão exercida pelo balonete e ao tempo de exposição. O objetivo foi estudar as eventuais lesões da mucosa do segmento traqueal em contato com o balonete do tubo traqueal insuflado com volume de ar suficiente para se obter pressão de “selo” ou com a pressão limite de 25 cmH2O, abaixo da pressão crítica de 30 cm de água para produção de lesão da mucosa traqueal. MÉTODO: Dezesseis cães foram submetidos à anestesia venosa e ventilação artificial. Os cães foram distribuídos aleatoriamente em dois grupos de acordo com a pressão no balonete do tubo traqueal (Portex Blue-Line, Inglaterra: Gselo (n = 8 balonete com pressão mínima de “selo” para impedir vazamento de ar durante a respiração artificial; G25 (n = 8 balonete insuflado até obtenção da pressão de 25 cmH2O. A medida da pressão do balonete foi realizada por meio de manômetro digital no início (controle e após 60, 120 e 180 minutos. Após o sacrifício dos cães, foram feitas biópsias nas áreas da mucosa traqueal adjacentes ao balonete e ao tubo traqueal para análise à microscopia eletrônica de varredura (MEV. RESULTADOS: A pressão média do balonete em G25 manteve-se entre 24,8 e 25 cmH2O e em Gselo entre 11,9 e 12,5 cmH2O durante o experimento. As alterações à MEV foram pequenas e não significantemente diferentes nos grupos (p > 0,30, mas ocorreram lesões mais intensas nas áreas de contato da mucosa traqueal com o balonete do tubo traqueal, nos dois grupos, em relação às áreas da mucosa adjacentes ou não ao tubo traqueal (p JUSTIFICATIVA Y OBJETIVOS: Las lesiones de la mucosa traqueal en contacto con el balón del tubo traqueal son proporcionales a la presión ejercida por el balón y al tiempo de exposición. La finalidad fue estudiar las eventuales lesiones de la mucosa del segmento traqueal en contacto con el bal

  18. Utilidad de la ecografía en el diagnóstico de los pacientes con sospecha de neoplasias del tubo digestivo Uselfulness of ultrasonography in diagnosing patients suspect for digestive tract neoplasms

    Directory of Open Access Journals (Sweden)

    D. Martínez Ares

    2008-09-01

    Full Text Available Introducción: el valor predictivo positivo de síntomas y signos en el diagnóstico del cáncer de colon y gástrico es bajo. Además, muchos pacientes son remitidos para descartar una neoplasia digestiva, sin síntomas que sugieran su localización, siendo el VPP de la clínica aún menor. En este trabajo evaluamos la utilidad de la ecografía como primera aproximación diagnóstica. Material y método: se han reclutado 79 pacientes (48 varones, edad media 69,3 años. En todos ellos se realiza una ecografía antes de la endoscopia. Se evalúa la precisión en el diagnóstico del cáncer de colon y gástrico, los diagnósticos ecográficos y el número de endoscopias que se evitarían. También se buscan factores predictivos de la localización de la neoplasia. Resultados: se han diagnosticado 5 neoplasias gástricas (6,3% y 12 de colon (19%, 3 cáncer de páncreas (3,8%, 2 neoplasias uterinas (2,5% y 2 hipernefromas (2,5%. Las cifras de sensibilidad, especificidad, VPP, VPN y precisión de la ecografía fueron 80%, 98,6%; 80%; 98,6%; y 97,4% respectivamente en el diagnóstico del cáncer gástrico, y del 100%, 94,5%; 80%; 100% y 95,5% respectivamente en el diagnóstico del cáncer de colon. La ecografía permitió evitar el 10% de las endoscopias. El único dato que orienta la localización de la neoplasia es la presencia de anemia, que se asocia con mayor frecuencia al diagnóstico de cáncer de colon: 30,4 versus 4,3% (p = 0,033. Conclusiones: en los pacientes remitidos para descartar una neoplasia digestiva, con síntomas inespecíficos, se diagnostica con frecuencia de patología neoplásica ajena al tubo digestivo. Si consideramos, además, la elevada precisión diagnóstica de la ecografía, esta podría ser una muy buena primera aproximación diagnóstica.Background: the Positive Predictive Value (PPV of signs and symptoms for the diagnosis of colon and gastric cancer is low. Furthermore, many patients are referred to us to discard a

  19. Mortality due to neural tube defects and risk factors in Hidalgo, Mexico

    OpenAIRE

    Muñoz-Juárez, Sergio; Vargas-Flores, Humberto; Hernández-Prado, Bernardo; López-Ríos, Olga; Ortiz-Espinosa, Rosa María

    2002-01-01

    Objetivo. Calcular el riesgo de muerte fetal secundaria a defectos del cierre del tubo neural y estimar factores asociados con este tipo de muertes en el estado de Hidalgo. Material y métodos. La información analizada en el año 2000 fue obtenida de los certificados de muerte fetal del periodo 1990-1995 en el estado de Hidalgo. Se utilizó un diseño de mortalidad proporcional, considerado como una variante del diseño de casos y controles. Los casos fueron aquellas muertes fetales secundarias a ...

  20. Dosagem de folatos maternos e fetais, séricos e eritrocitários em malformações por defeito de fechamento do tubo neural no feto Maternal and fetal serum and red blood cell folate levels in pregnancies complicated by neural tube defects

    Directory of Open Access Journals (Sweden)

    Victor Bunduki

    1998-07-01

    Full Text Available Objetivos: avaliar os níveis de folatos maternos e fetais gestações com malformações por defeitos de fechamento do tubo neural (DFTN. Métodos: o estudo foi do tipo caso-controle, no qual 14 casos de fetos com DFTN (grupo estudo e 14 casos de fetos com outras malformações (grupo controle foram estudados em gestantes de baixo risco para DFTN. Propusemo-nos a dosar o ácido fólico, na sua forma total e metilada, nos compartimentos fetal e materno, utilizando dosagens séricas e tissulares (eritrocitárias, assim como o volume corpuscular médio, o hematócrito e a hemoglobina. As coletas foram realizadas imediatamente antes da interrupção da gestação. Os resultados nos dois grupos foram comparados pelo teste t de Student, método de amostras pareados pela idade gestacional. Resultados: não se encontrou diferença nas taxas de folatos fetais e nos parâmetros hematológicos dos fetos, entre os dois grupos. Por outro lado, taxas anormalmente baixas de folatos foram encontradas nos eritrócitos das mães portadoras de fetos com DFTN, tanto para as formas totais(293,9 ng/mL contra 399,1 ng/mL no grupo controle, p=0,01 quanto para as formas metiladas (201,9 ng/mL contra 314,0 ng/mL para o grupo controle, p=0,02. Os folatos séricos maternos não se mostraram diferentes nos grupos estudo e controle. Conclusão: este estudo demonstrou que há uma menor taxa de folatos intratissulares, nas mães de fetos acometidos por DFTN, porém com taxas de folatos séricos semelhantes em relação ao grupo controle.Objective: to analyze maternal and fetal folate status in cases of neural tube defects (NTD. Methods: a case-control study was designed with 14 cases of fetuses with neural tube defects (study group and 14 cases of fetuses with other unrelated malformations (control group gestational age matched, in low-risk pregnant women. Both total and methylated folic acid levels in fetal and maternal compartments using serum and tissular (red blood cells

  1. Software para la enseñanza de la dinámica y control de intercambiadores de calor de tubos y coraza

    Directory of Open Access Journals (Sweden)

    Fiderman Machuca

    2008-01-01

    Full Text Available Este trabajo presenta la estructura de un software desarrollado para la enseñanza y aprendizaje de la dinámica y control de intercambiadores de calor de tubos y coraza. El programa presenta, de manera numérica y gráfica, el comportamiento dinámico en lazo abierto y cerrado del proceso para diferentes parámetros de diseño y condiciones de operación variables. El software permite modificar condiciones tanto de operación como de diseño, por ejemplo, temperatura y caudales de entrada a los tubos y coraza, número y longitud de tubos, número de pasos, diámetro externo e interno de los tubos, diámetro interno de coraza y factor de ensuciamiento.

  2. Aplicación del Método de la Colonia de Hormigas Mixto a la optimización de intercambiadores de calor de tubo y coraza//Application of the Mixed Ant Colony Method to the optimization of tube and shell heat exchangers

    Directory of Open Access Journals (Sweden)

    Maida Bárbara Reyes‐Rodríguez

    2014-05-01

    Full Text Available Los procesos de transferencia de calor sonuno de los problemas más importantes a resolver en el campo de la Ingeniería. Entre los equipos más usados en la industria para realizar la transferencia de calor están los intercambiadores de calor de tubo y coraza. En el presente trabajo se desarrolla el procedimiento para la optimización del diseño de estos equipos utilizando el método de Kern y aplicando el algoritmo de la colonia de hormigas. Se aplica el mismo a tres ejemplos concretos y los resultados obtenidos se comparan con los obtenidos aplicando otros métodos de la inteligencia artificial. Se optimizan los principales parámetros geométricos de los intercambiadores de calor de tubo y coraza para lograr un menor costo de los mismos. Se demuestra la eficacia del nuevo procedimiento MACO (Mixed Ant Colony Optimization, en el proceso de optimización desde el punto de vista económico utilizando diferentes casos de estudios.Palabras claves: intercambiadores de calor, colonia de hormigas, método de Kern.______________________________________________________________________________AbstractHeat transfer processes are one of the most important problems to be solved in the field of Engineering. Among the most widely used equipment for heat transfer in the industry are the shell and tube heat exchangers. This paper develops the procedure for optimizing the design of shell and tube heat exchangers using the method of Kern and applying the ant colony algorithm. The procedure has been applied to three specific examples and the results obtained are compared with those obtained by applying other methods of artificial intelligence. The main geometric parameters of shell and tube heat exchangers are optimized, to achieve a lower cost of the exchanger. The efficacy of the new procedure MACO (Mixed Ant Colony Optimization for the optimization process from economically point of view was demonstrated, using different case studies.Key words: heat

  3. Dimensionamiento de intercambiadores de calor de coraza y tubos, con ayuda de computador

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    Gabriel Eduardo Rocha Camino

    1985-09-01

    Full Text Available En este trabajo se plantea el problema de optimizar el diseño de un intercambiador de calor del tipo coraza y tubos, y se propone un método para resolverlo, con base en la técnica del "estudio paramétrico de la respuesta". Además, se muestra la necesidad de utilizar el computador como herramienta para Implementar dicho método, y se describe un programa escrito con tal fin.

  4. Comportamiento de tubos circulares de hormigón simple producidos con adición de caucho de neumáticos

    Directory of Open Access Journals (Sweden)

    J Akasaki

    Full Text Available En este trabajo se estudiaron tubos de hormigón simple elaborados con la adición de caucho de neumáticos en proporciones de 10, 15 y 20 kg/m³ de hormigón. El programa experimental incluye la realización de ensayos de resistencia a la compresión diametral y absorción de agua. Se evaluaron doce tubos, con un diámetro nominal (DN de 600 mm y longitud de 1500 mm, separados en cuatro series de tres tubos cada una. Cada serie estaba formada por tres tubos tipo punta y bolsa (PB: una serie de control (sin caucho de neumáticos y tres series con incorporación de tres diferentes concentraciones de caucho en la mezcla para los tubos (TB1, TB2 e TB3. Todos los resultados de los ensayos de resistencia a la compresión diametral presentaron valores superiores a los especificados en la norma NBR 8890 para los tubos de hormigón simple clase PS2: tipo PB con DN de 600 mm, cuyo valor es de 36 kN/m. En los ensayos de absorción de agua, todos los tubos presentaron valores de absorción inferiores al máximo establecido en la norma NBR 8890, cuyo valor es de 8%. Se puede concluir, que el caucho de neumático tiene potencial para ser incorporado en la fabricación de tubos de hormigón simple. No obstante, es imperativo ampliar el conocimiento sobre el comportamiento del hormigón preparado con caucho de neumáticos.

  5. Multiple excitation of supports - Part 2 : Implementation in TUBO system

    International Nuclear Information System (INIS)

    Galeao, A.C.N.R.; Barbosa, H.J.C.

    1980-12-01

    From the formulation of multiple excitation support problem, discussed in the first part of this work, and with the use of numerical techniques presented there, we discuss in this second part, the implementation in TUBO system, the follow procedure: Direct integration, Modal overlap, Spectral response emphasizing the aspects related to supports excitation. Finally, we present two numerical examples of TUBO system utilization in the solution of support movement problem. The several implemented computational procedures are compared. (E.G.) [pt

  6. Tubo gástrico con conservación anatómica y funcional del píloro Gastric tube with anatomical and functional conservation of the pylorus

    OpenAIRE

    Albio Ferrá Betancourt; Sixto Corona Mancebo

    2008-01-01

    INTRODUCCIÓN. No existe consenso en cuanto a la realización de un procedimiento de drenaje gástrico cuando se ha realizado una esofagectomía subtotal y se ha sustituido el esófago por el estómago tubulizado y desnervado. Es el objetivo de este estudio evaluar el resultado obtenido en pacientes a quienes se practicó esofagectomía subtotal y sustitución del órgano con estómago tubulizado sin aplicar drenaje gástrico (piloroplastia). MÉTODOS. Se analizaron 16 pacientes tratados con este procedim...

  7. MR imaging of tubo-ovarian abscess

    International Nuclear Information System (INIS)

    Ha, H.K.; Lim, G.Y.; Cha, E.S.; Lee, H.G.; Ro, H.J.; Kim, H.S.; Kim, H.H.; Joo, S.W.; Jee, M.K.

    1995-01-01

    MR findings of 9 surgically proven tubo-ovarian abscesses were analyzed in 8 patients. The images were evaluated for signal intensity characteristics and morphologic appearance of the mass, and presence of secondary changes in adjacent pelvic organs and structures. The signal intensity of the lesions on T1-weighted images was hypointense to the surrounding muscle and myometrium in 5 patients, isointense in 3 and hyperintense in 1. On T2-weighted images the signal intensity was hyperintense (n=6) or heterogeneous (n=3). A thin rim (1-3 mm) with hyperintensity on T1-weighted images was noted in the innermost aspect of the masses. Other findings were ill-defined margin, thickened wall, multiple internal septa, shading and gas collection. ''Mesh-like'' linear strands were noted in the pelvis in all patients, with involvement of adjacent pelvic organs in 7 and lymphadenopathy in 3. In this limited number of cases MR imaging showed great potential for demonstrating the extent of the disease, characterizing the lesions and making a specific diagnosis. (orig.)

  8. CT and MRI diagnosis of tubo-ovarian masses

    International Nuclear Information System (INIS)

    Xiong Minghui; Zhang Wanshi; Wang Dong

    2000-01-01

    Objective: To evaluate the diagnostic value of CT and MRI in tubo-ovarian masses. Methods: CT scan was performed in 67 patients with tubo-ovarian masses confirmed by pathology. 19 of them underwent MRI. Results: (1) 20 primary malignant ovarian tumors showed cystic,solid or cystic-solid masses; papillary projections on cystic wall; pelvic organs and pelvic wall invasion. Chocolate cysts with malignant degeneration exhibited small nodules on thickened cystic wall on CT and MRI. T 1 WI was better for revealing the lesions. (2) Of 11 cases of metastasis to tubo-ovary, 4 showed peritoneal linear enhancement. (3) There were 9 cystadenomas and 2 adenofibromas, one of the cystadenomas contained fat, two adenofibromas were similar to uterus in density on CT while showing lower signal intensity on MRI (both T 1 WI and T 2 WI). (4) Three cases of thecoma exhibited cystic or solid masses, solid thecomas revealed granular enhancement. (5) Teratomas were most specific, one of them was associated with thecoma. (6) Tubo-ovarian abscesses and tuberculosis depicted cystic or cystic-solid masses. (7) Two cases of tubal pregnancy showed inhomogeneous soft tissue masses, the lower density areas in the centers were clot and organized tissues confirmed by pathology. Conclusion: (1) CT and MRI had higher sensitivity but lower specificity for tubo-ovarian masses, the diagnosis should be combined with clinical history and patients' age. (2) Tumors of two different types may coexist and sometimes fat may be present in tumors other than teratoma

  9. Pipe type poles in transmission power lines; Postes tipo tubo en lineas de transmision

    Energy Technology Data Exchange (ETDEWEB)

    Cervantes E, Mario; Becerril A, Armando [Luz y Fuerza del Centro, Mexico, D. F. (Mexico)

    1997-12-31

    The first supports for transmission power lines were relatively small structures, of simple configuration, to save reduced clearances to resist load in accordance with its need; with the technical development, gradually appeared higher and higher electric tensions and greater obstacles to overcome, consequently the design of the supports had to be adapted to the new conditions. This gave rise to the development of a specific technique that would adequate and incorporate the continuous engineering advances. In this document the initial considerations on the design poles pipe type are examined; within these considerations mention is made of: the design, the manufacture, the prototype tests, installation, quality control and foundations. The type tube pole is portrayed, as well as the steel reinforcement, finally the types of precast foundations are shown [Espanol] Los primeros soportes para lineas de transmision fueron estructuras relativamente pequenas, de configuracion simple, para salvar claros reducidos y resistir cargas proporcionales a sus necesidades, con el desarrollo de la tecnica, fueron apareciendo tensiones electricas cada vez mas elevadas y obstaculos mayores que vencer, por lo que el diseno de los soportes tuvo que adaptarse a las nuevas condiciones. Esto dio origen al desenvolvimiento de una tecnica especifica que fuese adecuando e incorporando los continuos avances de la ingenieria. En este documento se tratan las consideraciones iniciales del diseno de los postes tipo tubo; dentro de estas consideraciones se citan: el diseno, la fabricacion, las pruebas de prototipo, montajes, control de calidad y cimentaciones. Se ilustra el poste tipo tubo, al igual que el armado del poste, por ultimo se muestra los tipos de cimentaciones precoladas

  10. Hipanto e tubo estaminal em Xylopia aromatica (Lam.) Mart. (Annonaceae)

    OpenAIRE

    Dias, Marilda C.; Castro, Marília de M.; Kinoshita, Luiza S.; Semir, João

    1998-01-01

    (Hipanto e tubo estaminal em Xylopia aromatica (Lam.) Mart. (Annonaceae)). Observou-se, em corte longitudinal de flores de cinco espécies de Xylopia, um anel lenhoso ao redor dos carpelos e sobre ele, inserido de forma espiralada, o conjunto de estames e estaminódios. Para elucidar a natureza desta estrutura, foi realizado um estudo anatômico em flores adultas de Xylopia aromatica (Lam.) Mart., particularmente da vascularização desde a base do receptáculo até os estames, estaminódios e carpel...

  11. Conformado por vía coloidal de recubrimientos en la cara interna de un tubo de acero

    Directory of Open Access Journals (Sweden)

    Ferrari, B.

    2004-04-01

    fuertemente adheridos a la cara interna del tubo de acero.

  12. Tubo-ovarian abscess of tuberculous origin in the pediatric patient: a case report

    International Nuclear Information System (INIS)

    Rodriguez, Luz Stella; Moreno, Luz Angela; Henao, Liliana; Jaramillo, Lina; Montoya, Ruben Danilo

    2007-01-01

    We report a case of bilateral tuberculous tubo-ovarian abscess in a 13 year old girl which is noteworthy, because pelvic tuberculosis is an uncommon presentation of the disease in children, the diagnosis may be difficult. tuberculous tubo-ovarian abscess frequently mimic ovarian malignancies radiologically and clinically and their association with increased serum level of serum ea 125 in the absence of malignancy. Risks factors, CT and MRI appearances are essentials for their differentiation. The possibility of tubo-ovarian abscess must be considered in all women who presents with abdominal pain and adnexal mass regardless of their sexual activity

  13. Los principios de la terapia neural desde los fundamentos del nervismo hasta la neurociencia actual The principles of neural therapy from the foundations of nervism to current neuroscience

    Directory of Open Access Journals (Sweden)

    Faneth Toscano De La Torre

    2012-12-01

    Full Text Available Introducción: La terapia neural es un tipo de medicina alternativa de origen relativamente reciente, por lo cual constituye un sistema médico complejo en construcción. Hasta el momento, no se ha realizado una síntesis conceptual que permita formular los principios teóricos que sustentan su corpus doctrinario como sistema médico complejo. Objetivo: Formular los principios teóricos que sustentan el corpus doctrinario de la terapia neural. Metodología: Se revisó la literatura de la escuela neurofisiológica inglesa, la escuela rusa pavloviana, además de trabajos de investigación en el área de terapia neural, para poder realizar la formulación de los principios con un carácter general y de este modo sustentarlos en premisas que de preferencia cumplieran con las características de inducción cualitativa, las cuales desde la lógica peirceana confieren un alto grado de veracidad y rigurosidad lógico-científica. Resultados: Se realizó una síntesis lógica de las inferencias, de las que se obtuvieron 7 enunciados con el estatuto final de principio. Conclusiones: La descripción de los principios realizada en este trabajo es un aporte para la construcción del corpus doctrinario de la terapia neural como sistema médico complejo. Salud UIS 2012; 44 (2:57-65Introduction: Neural therapy is a type of alternative medicine of relatively recent origin, so is a complex medical system under construction. So far, it has not made a conceptual synthesis that allows formulating the theoretical principles underpinning its doctrinal corpus as complex medical system. Objective: To develop the theoretical principles that underlines the doctrinal corpus of neural therapy. Methodology: Literature review neurophysiological school English Russian Pavlovian school, in addition to research in the area of neural therapy, in order to make the formulation of a general principles and thus sustain them in premises of preference comply with the qualitative

  14. Multi-channel recording of a pulse spectrum on the screen of a Williams tube used with a ferrite memory analyser; Enregistrement du spectre d'impulsion sur l'ecran d'un tube de Williams au moyen d'un analyseur multicanal a memoire en ferrite; Zapis' spektra impul'sov na ehkrane ehlektronno-luchevoj trubki mnogokanal'nogo analizatora s ferritovoj pamyat'yu; Registro multicanal del espectro de los impulsos en la pantalla del tubo electronico, en un analizador con memoria de ferrita

    Energy Technology Data Exchange (ETDEWEB)

    Rumler, Shtirad [Institut Yadernogo Issledovannya Chekhoslovatskoj Akldemii Nauk, Rzhezh Chekhoslovatskaya Sotsialisticheskaya Respublika (Czech Republic)

    1962-04-15

    mentionne. Cet enregistrement n'est pas assez precis, notamment lorsqu'on analyse des intermittentes caracterisees par une basse frequence de repetition et une faible moyenne du nombre des impulsions. La raison en est que le dechiffrage de l'information fournie s'effectue dans le canal a partir des circuits additionneurs et des circuits , l'enregistrement se passant directement sur l'ecran. L'insuffisance de l'enregistrement direct s'explique par la moyenne faible du nombre des impulsions et par leur distribution statistique. La methode proposee se revele dans le cas considere comme plus satisfaisante; en effet, la qualite de l'enregistrement ne depend ni de la forme du spectre ni de la vitesse de comptage des impulsions. Elle est utilisee dans le selecteur a 256 canaux dont la memoire en ferrite presente un temps mort de 15 microsecondes. Le cycle de la representation oscillographique alterne periodiquement avec celui de l'analyse du spectre a mesurer, la frequence de base etant de 50 Hz. Le temps necessaire a l'enregistrement oscillographique est d'environ 4 millisecondes soit 20% de la duree totale du cycle d'utilisation du selecteur dans les selecteurs ayant un nombre de canaux plus petit et une memoire en ferrite a temps mort plus court; la duree de l'enregistrement oscillographique ne represente qu'un faible pourcentage de la duree du cycle d'utilisation. (author) [Spanish] Se describe un diagrama de conjunto aplicable al establecimiento de programas operativos que permiten el registro multicanal de un espectro creciente de impulsos analizados en la pantalla del tubo electronico, en combinacion con una memoria estatica de ferrita. Los dipositivos comunes de registro directo en el tubo electronico, en algunos casos, resultan imperfectos en un analizador del tipo indicado. Se comprueba que el registro no es suficientemente claro, especialmente cuando se trata de analizar de impulsos momentaneos con baja frecuencia de repeticion y cuyo

  15. Malformaciones del sistema nervioso central en una familia

    Directory of Open Access Journals (Sweden)

    Elisa Dyce Gordon

    1998-06-01

    Full Text Available Se reporta la aparición de 3 malformaciones del sistema nervioso central (2 defectos del tubo neural y una hidrocefalia en la progenie de un matrimonio entre primos y se establece una posible relación entre la aparición de estos defectos y las herencias multifactorial y autosómica recesiva. Se recomienda evitar el matrimonio entre parientes, así como ofrecer asesoramiento genético y diagnóstico prenatal a todas las personas que han procreado un hijo con malformaciones del sistema nervioso centralIt is reported the appearance of 3 malformations of the central nervous system (2 defects of the neural tube and 1 hydrocephaly in the offspring of a marriage between cousins. A possible relationship between appearance of these defects and the multifactorial and recessive autosomal inheritances is established. It is recommended to avoid marriage between relatives, as well as to offer genetic counseling and prenatal diagnosis to all those persons who had procreated a child with malformations of the CNS

  16. Sistema de Monitoreo Electrónico de Desplazamiento de Tubos de Extensión para Junta Expansiva

    Directory of Open Access Journals (Sweden)

    J. Campuzano-Cervantes

    2017-07-01

    Full Text Available Resumen: En este trabajo se plantea el desarrollo de un dispositivo, llamado junta expansiva, para mitigar la ruptura de tuberías para el transporte de hidrocarburos, causada por deslizamientos de tierra o dilatación lineal. La solución propuesta, involucra el desplazamiento de 2 tubos que alargan el dispositivo, aliviando la tensión y retardando la ruptura de la tubería. La medida del desplazamiento de esos tubos, requiere ser monitoreada para determinar qué tan pronto ocurrirá la ruptura y emprender las acciones correctivas para evitar el derramamiento del hidrocarburo, razón por la que se plantea este sistema de monitoreo electrónico con interfaz gráfica de usuario que facilita la visualización del desplazamiento de manera remota. De esta forma se complementa la junta expansiva y se ofrece la posibilidad al operador de mantenimiento de la tubería monitoreada, de reaccionar a tiempo. Las pruebas ejecutadas mostraron la funcionalidad del sistema de monitoreo propuesto en la junta expansiva. Abstract: In this work the development of a device, called an expansion joint, is proposed to mitigate the rupture of pipelines for the transportation of hydrocarbons, caused by landslides or linear expansion. Proposed solution involves the displacement of two tubes which extend the device, relieving tension and slowing the rupture of the pipe. The measurement of displacement needs to be monitored to determine how soon the rupture occur and take corrective actions to prevent spillage of hydrocarbons. Then, a system of electronic monitoring with graphical user interface that facilitates the visualization of displacement remotely is proposed, complementing the expansion joint. Operators can maintain the monitored pipe and react in time. The tests performed showed the functionality of the proposed system in the expansion joint. Palabras clave: Junta expansiva, sistema de control monitoreado, transporte de hidrocarburos, tuberías, interfaz gr

  17. Biodesulfurización de queroseno con células inmovilizadas de Pseudomonas sp. No. 6 (aislado nativo) en un novedoso biorreactor de lecho de tubos con recirculación

    OpenAIRE

    Silva, Edelberto; Caicedo, Luis; Pulido, Paula; Lentijo, Iván

    2006-01-01

    En este trabajo se realizó la biodesulfurización de queroseno con células inmovilizadas de Pseudomonas sp. ATCC 39327, en un sistema emulsionado, W/O 30/70 (v/v), con medio mínimo de sales (MMS) como fase dispersa. El sistema de inmovilización consta de dos paneles de 60 tubos cada uno. Los tubos de alta alúmina tienen 140 mm de largo, 6,6 mm de diámetro externo y 3,2 mm de diámetro interno, con una porosidad del 43% y capacidad de retención de 9,5x109 células/g de soporte, colocados dentro d...

  18. LA DINÁMICA DE FLUIDOS COMPUTACIONAL, SU APLICACIÓN AL ESTUDIO DE LAS CARACTERÍSTICAS DE UN INTERCAMBIADOR DE TUBOS TÉRMICOS

    Directory of Open Access Journals (Sweden)

    David Fernández Rivas

    2005-09-01

    Full Text Available Para el estudio y el diseño de un intercambiador de calor del tipo Termosifón se emplea por primera vez enCuba una novedosa técnica de modelación numérica, la Dinámica de Fluidos Computacional, uso quepudiera ahorrar al país numerosos recursos. Este trabajo continua, con nuevos aportes, una largainvestigación que ha tenido como objetivo central, la instalación de tubos térmicos termosifón (ITTT. Lasimulación computacional, es una poderosa herramienta que se emplea para conocer parámetros de interésen la operación de dicha instalación. Se trabaja con programas de Dinámica de Fluidos Computacional(DFC para acortar el tiempo de experimentación y ahorrar recursos materiales y humanos durante elestudio de diferentes variantes de arreglos geométricos de los tubos térmicos. Se logran conocer lasparticularidades que los diferentes arreglos de tubos introducen al proceso de intercambio de calor. Esteresultado brinda una importante contribución para la futura construcción de un termosifón a escalaindustrial. Esta investigación ha suscitado mucho interés por lo que pudiera significar para la eficiencia de lacaldera las nuevas condiciones impuestas por la quema de combustible cubano.Palabras Claves: Dinámica de Fluidos Computacional, Tubos térmicos, termosifón.__________________________________________________________________________AbstractThe Computational Fluids Dynamic it is used for studying a thermosyphon heat exchanger like a noveltechnique of numeric modeling, for the first time in Cuba. This technique could save a lot of resources. Thiswork is the continuation of a long research in the heat pipes technology. Working with Computational FluidsDynamic (DFC programs, consumes less time in the experimentation and allows saving material andhuman resources for these studies. It is possible to know many particularities of different geometries of tubesarrangements. This investigation will guarantee a future thermosyphon

  19. Multi-gate Pitot tube for the measurement of water flow in cooling systems; Tubo de Pitot multi-puertos para la medicion de flujo de agua en sistemas de enfriamiento

    Energy Technology Data Exchange (ETDEWEB)

    Figueroa Ibarra, Luis; Rodriguez Martinez, Jose Hugo; Santabarbara Botello, Marcelino [Instituto de Investigaciones Electricas, Cuernavaca, Morelos (Mexico)

    2007-07-01

    In this article the design of a novel measuring device of water flowing in large diameter pipes is described. A description is made of the instrument commonly used at present for this purpose (simple Pitot tube), whose design is based on the Standard CTI Code ATC-105 published by the Cooling Tower Institute (CTI ATC-105, 2000). The disadvantages of the simple Pitot tube in comparison with the new proposed device are emphasized (Multi-gate Pitot tube), of which its construction and design is described in detail. In the present article are also shown the results obtained of the circulation water flow measurements, performed in the cooling system of a fossil fuel power plant. These results are compared with the results of flow measurement obtained by means of the simulation of the thermodynamic cycle of the power station, using commercial software. [Spanish] En este articulo se describe el diseno de un novedoso medidor de flujo de agua que circula en tuberias de gran diametro. Se hace una descripcion del instrumento comunmente usado en la actualidad para dicho proposito (tubo de Pitot simple), cuyo diseno se basa en el estandar CTI Code ATC-105 publicado por el Cooling Tower Institute (CTI ATC-105, 2000). Se puntualizan las desventajas del tubo de Pitot simple en comparacion con el nuevo dispositivo propuesto (tubo de Pitot Multi-puertos), del cual se describe detalladamente su construccion y diseno. En el presente articulo tambien se muestran los resultados obtenidos de las mediciones de flujo de agua de circulacion, realizadas en el sistema de enfriamiento de una central termoelectrica. Dichos resultados son comparados con los resultados de flujo obtenidos mediante simulacion del ciclo termodinamico de la central, usando un software comercial.

  20. Sonographic features of tubo-ovarian abscess mimicking an endometrioma and review of cystic adnexal masses

    OpenAIRE

    Velcani, Artur; Conklin, Patrick; Specht, Neil

    2010-01-01

    A 36-year-old female presented with constant, worsening left lower quadrant pain without associated fever or vaginal discharge. Pelvic and transvaginal ultrasound examinations were performed which demonstrated a large complex cystic structure in the left adnexa with peripheral flow on color Doppler imaging. Given the sonographic appearance and patient symptoms, possibilities included endometrioma or hemorrhagic cyst. Tubo-ovarian abscess (TOA) and other cystic ovarian masses were considered l...

  1. Complejo tubo-ovárico: revisión de casos en el Hospital Nacional Cayetano Heredia (1990-1999

    Directory of Open Access Journals (Sweden)

    Ronald Roberto Sanchez Silva Torriani

    2003-07-01

    Full Text Available Objetivo: Determinar las características epidemiológicas, clínicas y de manejo del complejo tubo-ovárico (CTO.Material y métodos: Se realizó un estudio retrospectivo en 65 pacientes hospitalizadas con diagnóstico de complejo tubo-ovárico (CTO en el Servicio de Ginecología del Hospital Nacional Cayetano Heredia de Lima, Perú, entre Enero de 1990 y Diciembre de 1999. Se registraron datos demográficos, antecedentes patológicos, cuadro clínico, exámenes auxiliares, tratamiento médico, quirúrgico, hallazgos operatorios, complicaciones quirúrgicas, tiempo de hospitalización y seguimiento. Resultados: El complejo tubo-ovárico correspondió al 0.72% de las pacientes hospitalizadas en el servicio de Ginecología de este hospital. Este fue más frecuente entre la tercera y cuarta década de la vida (promedio = 31.9 años, en casadas (44.6% y multigestas (53.8%. El uso de dispositivos intrauterinos no tuvo relación estadísticamente significativa con la localización del CTO confirmado quirúrgicamente. Las manifestaciones clínicas más frecuentes fueron dolor pélvico (96.9%, fiebre (76.9%, dolor a la movilización cervical (60% y masa anexial (58.5%. La ecografía pélvica presentó mayor positividad en el diagnóstico de CTO (91.3%, luego de la laparoscopía (100%, aunque ésta se realizó solo en 4 casos. El drenaje de absceso más lavado de cavidad peritoneal tuvo similar porcentaje de complicaciones que las demás técnicas, pero en el seguimiento 2 pacientes (14.3% fueron reoperadas. En el seguimiento de 24 pacientes el dolor pélvico fue el problema más frecuente en 40% de casos. No hubo mortalidad en este estudio. Conclusiones: El complejo tubo-ovárico es una patología que compromete la capacidad reproductiva y función ovárica de la mujer. La ecografía es un examen que presentó alta positividad en el diagnóstico. La laparotomía exploratoria más drenaje de absceso y lavado de cavidad peritoneal es un tratamiento quir

  2. Liberare i suoni. Per una visione ecologica del sociale

    Directory of Open Access Journals (Sweden)

    Attila Bruni

    2008-12-01

    Full Text Available C’è un ponte. Sotto il ponte c’è un tubo. Sopra il ponte passano le macchine. Le vibrazioni prodotte dalle macchine vengono raccolte all’interno del tubo, armonizzate e re-immesse nell’ambiente attraverso alcuni amplificatori. E l’ambiente circostante prende una forma melodica. Attraverso questa ed altre installazioni, a partire dal 1987, Bruce Odland e Sam Auinger si propongono di mostrare le armonie e le voci che fanno da sfondo (o da eco agli spazi che abitiamo quotidianamente.

  3. Automatic guided wave communication system using steel pipes as communication channel for flood detection in steel offshoreoilrigs; Sistema automatico de comunicacion de ondas guiadas para la deteccion de tubos de refuerzo inundados en plataformas petroleras costa fuera

    Energy Technology Data Exchange (ETDEWEB)

    Mijarez Cstro, Rito; Martinez Ramirez, Fernando [Instituto de Investigaciones Electricas, Cuernavaca, Morelos (Mexico)

    2010-10-09

    An automatic guided wave Pulse Position Modulation (PPM) system, using steel tubes as communication channel, for detecting flooding in the hollow sub-sea structures of offshore oilrigs is presented. The system employs two smart piezoelectric based sensors and modulators and a demodulator based on a piezoelectric transducer, a Digital Signal Processor (DSP) and a microcontroller. Experiments performed in the laboratory, in a tubular steel heliport structure and the base of a deck of an oilrig under construction, have successfully distinguished automatically guided wave encoded information. [Spanish] Este articulo presenta un trabajo de investigacion en el cual se desarrolla un sistema automatico de comunicacion de ondas guiadas por modulacion por posicion de pulsos (PPM), orientado a la deteccion de miembros inundados en los tubos de refuerzo de las plataformas petroleras costa fuera. El sistema utiliza de manera novedosa tubos de acero como medio de comunicacion y emplea dos sensores/moduladores inteligentes compuestos de cristales piezoelectricos, electronica basada en un microcontrolador y baterias. La instrumentacion del demodulador consta de un transductor piezoelectrico de ultrasonido, un procesador digital de senales (DSP) y un microcontrolador, el cual lleva a cabo de manera automatica la deteccion de ondas guiadas. Los experimentos se realizaron en aire, en laboratorio, en una estructura tubular de acero del helipuerto y en la base de una plataforma bajo construccion.

  4. Complicaciones usuales post-drenaje pleural con tubos endotorácico en el trauma torácico no

    OpenAIRE

    Juan C Araujo-Cuauro; Fernando Fernández-Parra; Edwinis Garcia-Fontalvo; Milagros Sánchez

    2016-01-01

    Las lesiones por trauma torácico que ameriten hospitalización, y la inserción de un tubo endotorácico El objetivo de la investigación es identificar las complicaciones post-drenaje pleural con tubos endotorácico en el trauma torácico no quirúrgico. Se trata de estudio prospectivo descriptivo y observacional de las historias clínicas de admisión de los pacientes con traumatismo torácico contuso o penetrante no quirúrgico, que ingresaron durante el período co...

  5. Early telomere shortening and genomic instability in tubo-ovarian preneoplastic lesions.

    Science.gov (United States)

    Chene, Gautier; Tchirkov, Andrei; Pierre-Eymard, Eleonore; Dauplat, Jacques; Raoelfils, Ines; Cayre, Anne; Watkin, Emmanuel; Vago, Philippe; Penault-Llorca, Frederique

    2013-06-01

    Genetic instability plays an important role in ovarian carcinogenesis. We investigated the level of telomere shortening and genomic instability in early and preinvasive stages of ovarian cancer, serous tubal intraepithelial carcinoma (STIC), and tubo-ovarian dysplasia (TOD). Fifty-one TOD from prophylactic salpingo-oophorectomies with BRCA1 or 2 mutation, 12 STICs, 53 tubo-ovarian high-grade serous carcinoma, and 36 noncancerous controls were laser capture microdissected from formalin-fixed, paraffin-embedded sections, analyzed by comparative genomic hybridization (array CGH) and for telomere length (using quantitative real-time PCR based on the Cawthon's method). TOD and STICs were defined by morphologic scores and immunohistochemical expressions of p53, Ki67, and γH2AX. TOD showed marked telomere shortening compared with noncancerous controls (P STICs had even shorter telomeres than TOD (P = 0.0008). Ovarian carcinoma had shorter telomeres than controls but longer than STICs and dysplasia. In TOD, telomeres were significantly shorter in those with BRCA1 mutation than in those with BRCA2 mutation (P = 0.005). In addition, γH2AX expression in TOD and STIC groups with short telomeres was significantly increased (P STICs. The total number of genetic alterations was the highest in ovarian cancers. These findings suggest that genetic instability occurs in early stages of ovarian tumorigenesis. STICs and noninvasive dysplasia are likely an important step in early serous ovarian neoplasia. ©2013 AACR

  6. Análise das moléculas de matriz extracelular nas vias de migração das células de Crista Neural em embriões de aves (Gallus Gallus)

    OpenAIRE

    Portella, Ana Carolina Portugal

    2011-01-01

    Resumo: Após o fechamento do tubo neural, células da crista neural segregam-se da porção dorsal do tubo e migram por duas vias; a via ventral entre o somito e o tubo neural originando gânglios simpáticos e sensoriais, células de Schwann e células cromafins; e a via dorsolateral, originando melanócitos. Algumas moléculas parecem impedir a entrada de células da crista em somitos posteriores e em alguns sítios do tronco do embrião como por exemplo o espaço perinotocordal. Estas moléculas são o c...

  7. Assessment of a Chemotherapy Response Score (CRS) System for Tubo-Ovarian High-Grade Serous Carcinoma (HGSC)

    DEFF Research Database (Denmark)

    Ditzel, Helena M; Strickland, Kyle C; Meserve, Emily E

    2018-01-01

    A chemotherapy response score (CRS) system was recently described to assess the histopathologic response and prognosis of patients with tubo-ovarian high-grade serous carcinoma (HGSC) receiving neoadjuvant chemotherapy. The current study was performed as an independent assessment of this CRS syst...

  8. The ectopic appendicolith from perforated appendicitis as a cause of tubo-ovarian abscess

    International Nuclear Information System (INIS)

    Vyas, Rajashree C.; Sides, Corey; Klein, Deborah J.; Reddy, Sireesha Y.; Santos, Mary C.

    2008-01-01

    Acute appendicitis is a common surgical cause of abdominal pain in the pediatric population. History and physical examination are atypical in up to a third of patients. Known potential complications of untreated or delayed management of acute appendicitis include appendiceal perforation, periappendiceal abscess formation, peritonitis, bowel obstruction and rarely septic thrombosis of mesenteric vessels. We report an unusual complication of perforated appendicitis. A tubo-ovarian abscess developed secondary to appendicolith migration into the right fallopian tube in a patient who had undergone interval laparoscopic appendectomy for perforated appendicitis. The retained appendicolith was visualized within the obstructed and dilated fallopian tube on contrast-enhanced CT. We discuss the CT imaging features of this unusual complication of perforated appendicitis. (orig.)

  9. The ectopic appendicolith from perforated appendicitis as a cause of tubo-ovarian abscess

    Energy Technology Data Exchange (ETDEWEB)

    Vyas, Rajashree C.; Sides, Corey; Klein, Deborah J. [University of Rochester Medical Center, Rochester, NY (United States); Reddy, Sireesha Y. [University of Rochester, Obstetrics and Gynecology, Rochester, NY (United States); Santos, Mary C. [University of Rochester, Pediatric Surgery, Rochester, NY (United States)

    2008-09-15

    Acute appendicitis is a common surgical cause of abdominal pain in the pediatric population. History and physical examination are atypical in up to a third of patients. Known potential complications of untreated or delayed management of acute appendicitis include appendiceal perforation, periappendiceal abscess formation, peritonitis, bowel obstruction and rarely septic thrombosis of mesenteric vessels. We report an unusual complication of perforated appendicitis. A tubo-ovarian abscess developed secondary to appendicolith migration into the right fallopian tube in a patient who had undergone interval laparoscopic appendectomy for perforated appendicitis. The retained appendicolith was visualized within the obstructed and dilated fallopian tube on contrast-enhanced CT. We discuss the CT imaging features of this unusual complication of perforated appendicitis. (orig.)

  10. Metodología basada en redes neurales para interpretación de la resistividad del suelo en zonas urbanas. Methodology based on neural networks for earth resistivity interpretation in congested urban areas

    Directory of Open Access Journals (Sweden)

    Miguel Martínez Lozano

    2015-04-01

    Full Text Available Uno de los problemas que se afronta durante el diseño de un sistema de puesta a tierra (PAT en zonas urbanas, es la obtención de los parámetros eléctricos del suelo, ya que los métodos tradicionales de medición de resistividad no se pueden aplicar por problemas de espacio. En este trabajo, se plantea una alternativa para la obtención de la resistividad, mediante sondeo eléctrico introduciendo una barra vertical y registrando cómo varía la resistencia de PAT del electrodo en función de la profundidad; con esos resultados se desarrolla una metodología basada en redes neurales, para estimar los parámetros del suelo para un modelo biestratificado del mismo. Se estudia por tanto, el tema de las complicaciones de medición en zonas urbanas y se plantea en detalle la metodología empleando técnicas modernas de medición y procesamiento. Los resultados obtenidos, tanto en fase de simulación digital como con ensayos de campo, muestran la validez.  One of the main troubles for grounding system design in an electrical installation on congested urban areas is obtaining the soil parameters, since the traditional measurements techniques are not applicable due to the limited space. In the present work, an alternative procedure based on introducing a driven rod into the soil and registering the variation of ground resistance versus the depth, is presented; with the field measurements obtained, a procedure were evaluated to estimate the soil parameters in a simplified bi-stratified model (two vertical layers using a trained neural network to minimize the effort and time to obtain the respective results. The trouble about the measurement and estimation of electrical soil properties in congested urban areas is solved with the detailed methodology presented, based on non conventional measurement techniques and computational processing. The results obtained during both digital simulation and field measurements, demonstrates the validity of the

  11. Study of the internal heat transfer of the water flow in nucleate boiling; Estudio de la transferencia de calor del flujo interno de agua en ebullicion nucleada

    Energy Technology Data Exchange (ETDEWEB)

    Payan Rodriguez, Luis Alfredo

    2003-09-01

    In this paper the development of a research project oriented to the analysis of the heat transfer of the water flow in nucleate boiling is presented. Here a mathematical model is described to characterize the water flow in boiling condition in vertical tubes by means of which the temperature distributions in the tube wall and in the water flow are obtained, including the calculation of the pressure drop throughout the tube. In addition, a mechanistic model focused to the prediction of the critical heat flow in vertical tubes uniformly heated was modified to be applied in non-uniform heat flow conditions. The proposed mathematical models were used in a case study derived from a real problem in a thermoelectric power plant, where it was required to simulate the process of boiling in fireplace tubes of the steam generator to determine the causes of the faults that happened in a considerable number of tubes. With the obtained results it was possible to establish that the faults in the tubes of the analyzed steam generator were originated because the heat transfer rate in the fireplace reached critical values that caused the deviation of the nucleate boiling to film boiling, causing the diminution of the heat transfer coefficient with the consequent sudden increase in the tube wall temperature. [Spanish] En este trabajo se presenta el desarrollo de un proyecto de investigacion orientado al analisis de la transferencia de calor en flujo de agua en ebullicion nucleada. Aqui se describe un modelo matematico para caracterizar el flujo de agua en ebullicion en tubos verticales mediante el cual se obtienen las distribuciones de temperatura en la pared del tubo y en el flujo de agua, incluyendo el calculo de la caida de presion a lo largo del tubo. Ademas, un modelo mecanistico enfocado a la prediccion del flujo de calor critico en tubos verticales uniformemente calentados fue modificado para aplicarlo en condiciones de flujo de calor no uniforme. Los modelos matematicos

  12. Thermal and friction drop characteristic of heat exchangers with elliptical tubes and smooth fins//Caracterización térmica e hidráulica de intercambiadores de calor con tubos elípticos y aletas lisas

    Directory of Open Access Journals (Sweden)

    Rubén Borrajo-Pérez

    2012-09-01

    Full Text Available Pressure drop and heat transfer are the most important parameters in compact heat exchanger. There is a lack of information in the literature about heat exchanger with elliptical tube. The objective of this work was the experimental characterization of compact heat exchangers models using elliptical tube with eccentricity of 0,5 and smooth fins. The Reynolds numbers and the spacing were varied and always inside laminar regime. The experiments were conducted in an open wind tunnel using sublimation of naphthalene and the heat and mass transfer analogy. As results, the average and local Nusselt number and friction factor for 36 models were obtained. Correlations for Colburn and friction factors were presented. This correlations were obtained for 200tubos elípticos se trata. El objetivo del trabajo fue caracterizar experimentalmente modelos de intercambiadores de calor con tubos elípticos yaletas lisas. El numero de Reynolds y los espaciamientos fueron variados, dentro del régimen laminar. Los experimentos fueron desarrollados en un túnel de viento de circuito abierto usando la sublimación de naftaleno y la analogía calor y masa. Los números de Nusselt medio, locales y el factor de fricción fueronobtenidos en forma de correlaciones de Factores de Fricción y Colburn. Las correlaciones, validas para 200

  13. MODELADO DEL PRECIO SPOT DE LA ELECTRICIDAD EN BRASIL USANDO UNA RED NEURONAL AUTORREGRESIVA ELECTRICITY SPOT PRICE MODELLING IN BRASIL USING AN AUTOREGRESSIVE NEURAL NETWORK

    Directory of Open Access Journals (Sweden)

    Juan D Velásquez

    2008-12-01

    Full Text Available Una red neuronal autorregresiva es estimada para el precio mensual brasileño de corto plazo de la electricidad, la cual describe mejor la dinámica de los precios que un modelo lineal autorregresivo y que un perceptrón multicapa clásico que usan las mismas entradas y neuronas en la capa oculta. El modelo propuesto es especificado usando un procedimiento estadístico basado en el contraste del radio de verosimilitud. El modelo pasa una batería de pruebas de diagnóstico. El procedimiento de especificación propuesto permite seleccionar el número de unidades en la capa oculta y las entradas a la red neuronal, usando pruebas estadísticas que tienen en cuenta la cantidad de los datos y el ajuste del modelo a la serie de precios. La especificación del modelo final demuestra que el precio para el próximo mes es una función no lineal del precio actual, de la energía afluente actual y de la energía almacenada en el embalse equivalente en el mes actual y dos meses atrás.An autoregressive neural network model is estimated for the monthly Brazilian electricity spot price, which describes the prices dynamics better than a linear autoregressive model and a classical multilayer perceptron using the same input and neurons in the hidden layer. The proposed model is specified using a statistical procedure based on a likelihood ratio test. The model passes a battery of diagnostic tests. The proposed specification procedure allows us to select the number of units in hidden layer and the inputs to the neural network based on statistical tests, taking into account the number of data and the model fitting to the price time series. The final model specification demonstrates that the price for the next month is a nonlinear function of the current price, the current energy inflow, and the energy saved in the equivalent reservoir in the current month and two months ago.

  14. Generación de burbujas y análisis del mezclado en columnas de flujo oscilatorio

    OpenAIRE

    Meroño Nieto, Jose Antonio

    2015-01-01

    Los reactores de flujo oscilatorio (OBR) son equipos tubulares aptos para el mezclado intensivo, en los que se superpone un flujo neto y un flujo oscilatorio. La velocidad del flujo neto que atraviesa el tubo es propia de un flujo laminar con muy bajo número de Reynolds, mientras que las velocidades superpuestas por la oscilación de tipo sinusoidal pueden ser de hasta tres órdenes de magnitud mayor. Los tubos contienen elementos insertados que promueven el mezclado radial -típicamente coronas...

  15. Contaminación del aire por parque automotor en la ciudad de Puno

    OpenAIRE

    Marin Paucara, Esteban

    2007-01-01

    En el presente trabajo de tesis, denominado "Contaminación del aire por parque automotor en la ciudad de Puno", cuyo problema esta formulado mediante el siguiente enunciado: ¿Cuál es la relación que existe entre emisiones de gases (CO y HC) y opacidad, producidas a través del tubo de escape por el parque automotor y el nivel de contaminación del aire por este rubro en la ciudad de Puno?, siendo el objetivo general: Evaluar el nivel de contaminación del aire (calidad del aire) en relación a la...

  16. Implicaciones de las moléculas de adhesión celular neural en los efectos del estrés en procesos de aprendizaje y memoria en la rata

    OpenAIRE

    Merino Martín, José Joaquín

    2002-01-01

    Dado que las glicoproteínas denominadas moléculas de adhesión celular neural (NCAM, su forma polisializada, PSA-NCAM, y LI) desempeñan un papel importante en la consolidación de la memoria, se estudió su expresión en diferentes regiones cerebrales, en ratas entrenadas en el paradigma conductual del condicionamiento del miedo al contexto, bajo diferentes niveles de estrés intrínseco (ligado a la tarea de aprendizaje), y a diferentes tiempos post-entremamiento (12 y 24 horas). También se estudi...

  17. Differentiation between right tubo-ovarian abscess and appendicitis using CT-A diagnostic challenge

    Energy Technology Data Exchange (ETDEWEB)

    Eshed, I., E-mail: iriseshed@gmail.com [Department of Diagnostic Imaging, Sheba Medical Center, Tel-Hashomer, Sackler School of Medicine, Tel-Aviv University, Tel Aviv (Israel); Halshtok, O. [Department of Diagnostic Imaging, Sheba Medical Center, Tel-Hashomer, Sackler School of Medicine, Tel-Aviv University, Tel Aviv (Israel); Erlich, Z. [Computer Science Department, Open University, Tel Aviv (Israel); Mashiach, R. [Department of Obstetrics and Gynecology, Sheba Medical Center, Tel-Hashomer, Sackler School of Medicine, Tel-Aviv University, Tel Aviv (Israel); Hertz, M.; Amitai, M.M.; Portnoy, O.; Guranda, L. [Department of Diagnostic Imaging, Sheba Medical Center, Tel-Hashomer, Sackler School of Medicine, Tel-Aviv University, Tel Aviv (Israel); Hiller, N. [Department of Radiology, Hadassah-Hebrew University Medical Center, Mount Scopus (Israel); Apter, S. [Department of Diagnostic Imaging, Sheba Medical Center, Tel-Hashomer, Sackler School of Medicine, Tel-Aviv University, Tel Aviv (Israel)

    2011-11-15

    Aim: To determine CT features that can potentially differentiate right tubo-ovarian abscess (TOA) from acute appendicitis (AA; including abscess formation). Materials and methods: The abdominal computed tomography (CT) images of 48 patients with right-sided TOA (average age 39.3 {+-} 9.8 years) and 80 patients (average age 53.5 {+-} 19.9 years) with AA (24 with peri-appendicular abscess) were retrospectively evaluated. Two experienced radiologists evaluated 12 CT signs (including enlarged, thickened wall ovary, appendix diameter and wall thickness, peri-appendicular fluid collection, adjacent bowel wall thickening, fat stranding, free fluid, and extraluminal gas) in consensus to categorize the studies as either TOA or AA. The diagnosis and the frequency of each of the signs were correlated with the surgical and clinical outcome. Results: Reviewers classified 92% cases correctly (TOA = 85%, AA = 96.3%), 3% incorrectly (TOA = 6.3%, AA = 1.3%); 5% were equivocal (TOA = 8.3%, AA = 2.5%). In the peri-appendicular abscess group reviewers were correct in 100%. Frequent findings in the TOA group were an abnormal ovary (87.5%), peri-ovarian fat stranding (58.3%), and recto-sigmoid wall thickening (37.5%). An abnormal appendix was observed in 2% of TOA patients. Frequent findings in the AA group were a thickened wall (32.5%) and distended (80%) appendix. Recto-sigmoid wall thickening was less frequent in AA (12.5%). The appendix was not identified in 45.8% of the TOA patients compared to 15% AA. Conclusions: In the presence of a right lower quadrant inflammatory mass, peri-ovarian fat stranding, thickened recto-sigmoid wall, and a normal appearing caecum, in young patients favour the diagnosis of TOA. An unidentified appendix does not contribute to the differentiation between TOA and peri-appendicular abscess.

  18. Differentiation between right tubo-ovarian abscess and appendicitis using CT-A diagnostic challenge

    International Nuclear Information System (INIS)

    Eshed, I.; Halshtok, O.; Erlich, Z.; Mashiach, R.; Hertz, M.; Amitai, M.M.; Portnoy, O.; Guranda, L.; Hiller, N.; Apter, S.

    2011-01-01

    Aim: To determine CT features that can potentially differentiate right tubo-ovarian abscess (TOA) from acute appendicitis (AA; including abscess formation). Materials and methods: The abdominal computed tomography (CT) images of 48 patients with right-sided TOA (average age 39.3 ± 9.8 years) and 80 patients (average age 53.5 ± 19.9 years) with AA (24 with peri-appendicular abscess) were retrospectively evaluated. Two experienced radiologists evaluated 12 CT signs (including enlarged, thickened wall ovary, appendix diameter and wall thickness, peri-appendicular fluid collection, adjacent bowel wall thickening, fat stranding, free fluid, and extraluminal gas) in consensus to categorize the studies as either TOA or AA. The diagnosis and the frequency of each of the signs were correlated with the surgical and clinical outcome. Results: Reviewers classified 92% cases correctly (TOA = 85%, AA = 96.3%), 3% incorrectly (TOA = 6.3%, AA = 1.3%); 5% were equivocal (TOA = 8.3%, AA = 2.5%). In the peri-appendicular abscess group reviewers were correct in 100%. Frequent findings in the TOA group were an abnormal ovary (87.5%), peri-ovarian fat stranding (58.3%), and recto-sigmoid wall thickening (37.5%). An abnormal appendix was observed in 2% of TOA patients. Frequent findings in the AA group were a thickened wall (32.5%) and distended (80%) appendix. Recto-sigmoid wall thickening was less frequent in AA (12.5%). The appendix was not identified in 45.8% of the TOA patients compared to 15% AA. Conclusions: In the presence of a right lower quadrant inflammatory mass, peri-ovarian fat stranding, thickened recto-sigmoid wall, and a normal appearing caecum, in young patients favour the diagnosis of TOA. An unidentified appendix does not contribute to the differentiation between TOA and peri-appendicular abscess.

  19. MR findings of ruptured endometrial cyst: Comparison with tubo-ovarian abscess

    International Nuclear Information System (INIS)

    Suzuki, Shigeru; Yasumoto, Mayumi; Matsumoto, Reiko; Andoh, Akihiko

    2012-01-01

    Objective: To evaluate the MR findings of ruptured endometrial cyst, focusing on the differentiation from tubo-ovarian abscess (TOA). Patients and methods: We reviewed the records of 21 patients who underwent preoperative MR examinations for TOAs (n = 15) or ruptured endometrial cysts (n = 6). We evaluated the presence of hyper-intense ascites and hyper-intense peritoneum in T1-weighted sequences, strong enhancement of the peritoneum, hyper-intense content and hyper-intense rim of the ovarian lesion in T1-weighted sequences, and strong wall enhancement of the ovarian lesion. χ 2 test was used to assess the relationship between TOA cases versus cases with ruptured endometrial cysts, and the three MR peritoneal findings. We evaluated the relationship between TOA versus non-infected endometrial cysts, and the ovarian MR peritoneal findings, too. Results: Hyper-intense ascites was found in all of the patients with ruptured endometrial cyst and none with TOA (p < 0.0001). Hyper-intense peritoneum was observed in only TOAs cases (4 of 8). Strong peritoneal enhancement was seen in 3 of the 3 patients with ruptured endometrial cyst and 7 of the 13 patients with TOA (p = 0.1366). Hyper-intense content of the ovarian lesion was seen more often in the non-infected endometrial cysts than in the TOAs (p = 0.001607), while hyper-intense rim was more frequent in TOAs (p = 0.000402). Strong wall enhancement was observed only in TOAs (11 of 15) (p = 0.001355). Conclusions: MR images are useful to differentiate ruptured endometrial cyst from TOA.

  20. Morphological and immunohistochemical pattern of tubo-ovarian dysplasia and serous tubal intraepithelial carcinoma.

    Science.gov (United States)

    Chene, Gautier; Cayre, Anne; Raoelfils, Ines; Lagarde, Nicole; Dauplat, Jacques; Penault-Llorca, Frederique

    2014-12-01

    Histopathological examination of material from prophylactic salpingo-oophorectomies performed in patients at genetic risk of ovarian cancer can reveal abnormalities interpreted as possible pre-cancerous "ovarian dysplasia" and tubal precursors lesions. We sought to study the morphological features and immunohistochemical expression patterns of neoplasia-associated markers in prophylactically removed ovaries and fallopian tubes (pBSO) in comparison with a group of serous tubal intraepithelial carcinoma (STIC) and non-cancerous controls. Morphological features and immunohistochemical expression patterns of Ki-67 (for proliferation biomarker), p53 (key pathway of mullerian serous tumorogenesis), Bcl2 (anti-apoptotic), γH2AX (a double-strand breaks marker) and ALDH1 (a stem cell marker significantly associated with early-stage ovarian cancer) were blindly evaluated by two pathologists in 111 pBSO, 12 STICs and 116 non-cancerous salpingo-oophorectomies (control group) (nBSO). Morphological ovarian and tubal dysplasia scores were significantly higher in the pBSO than in controls (respectively, 8.8 vs 3.12, pSTICs compared with the controls whereas expression patterns of Ki67, p53 and bcl2 were low to moderate in the pBSO group. STICs overexpressed Ki67 and p53 while bcl2 expression was low; Interestingly, ALDH1 expression was low in non dysplastic epithelium, high in dysplasia and constantly low in STICs. The morphological and immunohistochemical profile of tubo-ovarian dysplasia and STICs might be consistent with progression toward neoplastic transformation in the Serous Carcinogenesis Sequence. These changes may be pre-malignant and could represent an important phase in early neoplasia. ALDH1 activation in pBSO samples and its extinction in STICs should be considered as a target for prevention. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

  1. MR findings of ruptured endometrial cyst: Comparison with tubo-ovarian abscess

    Energy Technology Data Exchange (ETDEWEB)

    Suzuki, Shigeru, E-mail: shig.suz@gmail.com [Department of Radiology, Saitama Red Cross Hospital, 8-3-33 Kamiochiai, Chuo-ku, Saitama, 338-8553 (Japan); Yasumoto, Mayumi, E-mail: Mayumihoo@yahoo.co.jp [Department of Radiology, Saitama Red Cross Hospital, 8-3-33 Kamiochiai, Chuo-ku, Saitama, 338-8553 (Japan); Matsumoto, Reiko, E-mail: rad@saitama-med.jrc.or.jp [Department of Radiology, Saitama Red Cross Hospital, 8-3-33 Kamiochiai, Chuo-ku, Saitama, 338-8553 (Japan); Andoh, Akihiko, E-mail: a-andoh@silk.plala.or.jp [Department of Obstetrics and Gynecology, Saitama Red Cross Hospital, 8-3-33 Kamiochiai, Chuo-ku, Saitama, 338-8553 (Japan)

    2012-11-15

    Objective: To evaluate the MR findings of ruptured endometrial cyst, focusing on the differentiation from tubo-ovarian abscess (TOA). Patients and methods: We reviewed the records of 21 patients who underwent preoperative MR examinations for TOAs (n = 15) or ruptured endometrial cysts (n = 6). We evaluated the presence of hyper-intense ascites and hyper-intense peritoneum in T1-weighted sequences, strong enhancement of the peritoneum, hyper-intense content and hyper-intense rim of the ovarian lesion in T1-weighted sequences, and strong wall enhancement of the ovarian lesion. {chi}{sup 2} test was used to assess the relationship between TOA cases versus cases with ruptured endometrial cysts, and the three MR peritoneal findings. We evaluated the relationship between TOA versus non-infected endometrial cysts, and the ovarian MR peritoneal findings, too. Results: Hyper-intense ascites was found in all of the patients with ruptured endometrial cyst and none with TOA (p < 0.0001). Hyper-intense peritoneum was observed in only TOAs cases (4 of 8). Strong peritoneal enhancement was seen in 3 of the 3 patients with ruptured endometrial cyst and 7 of the 13 patients with TOA (p = 0.1366). Hyper-intense content of the ovarian lesion was seen more often in the non-infected endometrial cysts than in the TOAs (p = 0.001607), while hyper-intense rim was more frequent in TOAs (p = 0.000402). Strong wall enhancement was observed only in TOAs (11 of 15) (p = 0.001355). Conclusions: MR images are useful to differentiate ruptured endometrial cyst from TOA.

  2. Tubo de Lester-Jones: indicações e resultados Lester-Jones tube: indications and results

    Directory of Open Access Journals (Sweden)

    Walberto Passos Junior

    2004-12-01

    Full Text Available OBJETIVO: Avaliar as indicações, resultados e complicações advindas do seu uso. MÉTODOS: Avaliaram-se retrospectivamente 25 pacientes submetidos a 27 conjuntivorrinostomias com colocação de tubo de Lester-Jones. Foram estudados os dados do portador, a etiologia da afecção e as complicações que ocorreram no intra e no pós-operatório. Os dados foram avaliados segundo a freqüência de ocorrência. RESULTADOS: O tubo de Lester-Jones foi usado igualmente em ambos os sexos, mais em indivíduos abaixo dos 10 ou acima dos 50 anos de idade. As causas mais freqüentes para utilização foram a idiopática ou a agenesia congênita de pontos e canalículos. Houve melhora dos sintomas em 88% dos pacientes. Complicações ocorreram em 59,25% dos casos, dentre as quais: extrusão (40,74% e a migração (14,8% do tubo. CONCLUSÃO: Apesar das complicações observadas, o índice de cura com a utilização do tubo de Lester-Jones é alto, sendo boa opção para o tratamento das obstruções lacrimais altas.PURPOSE: To evaluate the results and the complications occurring with this procedure. METHODS: The authors retrospectively reviewed charts of 25 patients (27 lacrimal viers with upper lacrimal system obstruction who underwent conjunctivorhinostomy and Lester-Jones tube bypass. The patients were evaluated according to gender, causative factors and the com plications during and after surgery. The data were submitted to statistical analysis. RESULTS: The Lester-Jones bypass tube was used in both sexes and most frequently in patients under 10 or above 50 years. The most common obstructive factor was unknown and congenital agenesis. Eighty-eight per cent of the patients had no epiphora at the end of the treatment. Complications occurred in 59.25% of the patients, most of them related to tube extrusion (40.74% or migration (14.8%. The authors concluded that the Lester-Jones bypass tube is a good option to treat the upper lacrimal obstruction, in spite

  3. Modelos analíticos no estudo do comportamento estrutural de tubos flexíveis e cabos umbilicais.

    OpenAIRE

    Roberto Ramos Junior

    2001-01-01

    Tubos flexíveis e cabos umbilicais têm sido bastante utilizados pela indústria petrolífera em aplicações offshore nos últimos anos. Os primeiros consistem num tipo de tubulação usada para o transporte de vários tipos de fluidos, geralmente trabalhando a alta pressão. Já os cabos umbilicais são usados para permitir o controle e a comunicação entre equipamentos submersos e de superfície. Quanto à concepção estrutural, os dois tipos de produto são muito semelhantes, apresentando diversas camadas...

  4. Determination of the load state of lead-acid batteries using neural networks; Determinacion del estado de carga de baterias plomo-acido utilizando redes neuronales

    Energy Technology Data Exchange (ETDEWEB)

    Cristin V, Miguel A; Ortega S, Cesar A [Instituto de Investigaciones Electricas, Cuernavaca, Morelos (Mexico)

    2005-07-01

    The charge of lead-acid batteries (LAB), as in any other type of batteries, consists of replacing the energy consumed during the discharge. Nevertheless, as no physical or chemical process is good enough to totality recharge a battery, it is necessary to supply to it more than the 100% of the energy demanded during its discharge. A critical factor to make a suitable load control of the batteries is to determine its own state of load. That is to say, to have an efficient load control, it is necessary to count on means that allow to accurately determining the residual capacity of the battery to deliver load. This one is the one of the aspects of greater interest in the research centers around world. For this reason, in this work it was pretended to develop a calculation algorithm of the state of load of batteries based on a fuzzy-neural network that could calculate the state of load without using the battery current as an input. This is because one of the main problems for the designers of battery load controllers is the correct supervision of the current that circulates around the system in all the rank of operation of the same one because the sensors do not have a linear behavior. [Spanish] La recarga de baterias plomo-acido (BPA), como cualquier otro tipo de baterias, consiste en reponer la energia consumida durante la descarga. Sin embargo, como ningun proceso fisico o quimico es lo bastante eficiente para recargar a totalidad una bateria, es necesario suministrarle mas del 100% de la energia demandada durante su descarga. Un factor critico para realizar un adecuado control de carga de las baterias, es determinar su propio estado de carga. Es decir, para tener un control de carga eficiente, es necesario contar con un medio que permita determinar con precision la capacidad remanente de la bateria para entregar carga. Este es uno de los aspectos de mayor interes en los centros de investigacion alrededor el mundo. Por tal razon, en este trabajo se propuso

  5. Análisis numérico de la distribución del tiempo de residencia en tipologías avanzadas de mezcladores tubulares

    OpenAIRE

    Femenía Martínez, Daniel

    2015-01-01

    Los reactores de flujo oscilatorio (OBR) son equipos tubulares aptos para el mezclado, en los que se superpone un flujo neto y un flujo oscilatorio. La velocidad del flujo neto que atraviesa el tubo es propia de un flujo laminar con muy bajo número de Reynolds, mientras que las velocidades superpuestas por la oscilación de tipo sinusoidal pueden ser de hasta tres órdenes de magnitud mayor. Los tubos contienen elementos insertados que promueven el mezclado radial -típicamente coronas circulare...

  6. Entupimento de tubos gotejadores convencionais com aplicação de cloreto de potássio (branco e vermelho) via duas qualidades de água

    OpenAIRE

    Ribeiro,Pabblo A. de A; Coelho,Rubens D; Teixeira,Marconi B

    2010-01-01

    Neste trabalho, buscou-se avaliar a suscetibilidade de modelos de tubos gotejadores ao entupimento, quando expostos ao uso de cloreto de potássio (branco e vermelho), aplicados via diferentes qualidades de água. O experimento foi realizado no Laboratório de Irrigação do Departamento de Engenharia Rural da Escola Superior de Agricultura "Luiz de Queiroz" ESALQ/USP, por um período de nove meses, analisando o desempenho de oito modelos de tubos gotejadores convencionais, com quatro tratamentos e...

  7. Avaliação e caracterização de tubos fabricados com PVC reciclado

    Directory of Open Access Journals (Sweden)

    Luiz Carlos G. Pennafort Jr

    2013-01-01

    Full Text Available Neste trabalho foram caracterizados dois polímeros utilizados na fabricação de tubos de PVC, tendo como diferencial o uso de resina de policloreto de vinila virgem e reciclada. O uso da resina reciclada, derivada do reprocessamento de resíduos aterrados (sanitários ou industriais, foi avaliado com o objetivo de compará-la a produtos fabricados com resina virgem, os quais foram submetidos aos ensaios de Fluorescência de Raios X (FRX, Difração de Raios X (DRX e resistência à tração e alongamento. Os resultados demonstraram que houve alteração estatisticamente significativa, conforme ANOVA (5%, nas características mecânicas do produto final, tendo os tubos fabricados com PVC reciclado apresentado uma resistência mecânica menor que os fabricados com resina virgem, além da presença de metais pesados como Pb (chumbo e Cd (cádmio.

  8. Simplified analytical modeling of the normal hole erosion test; Modelado analitico simplificado del ensayo normal de ersoion de tubo

    Energy Technology Data Exchange (ETDEWEB)

    Khamlichi, A.; Bezzazi, M.; El Bakkali, L.; Jabbouri, A.; Kissi, B.; Yakhlef, F.; Parron Vera, M. A.; Rubio Cintas, M. D.; Castillo Lopez, O.

    2009-07-01

    The role erosion test was developed in order to study erosion phenomenon which occurs in cracks appearing in hydraulic infrastructures such as dams. This test enables describing experimentally the erosive characteristics of soils by means of an index which is called erosion rate and a critical tension which indicates the threshold of surface erosion initiation. The objective of this work is to five modelling of this experiment by means of a simplified analytical approach. The erosion law is derived by taking into account the flow regime. This law shows that the erosion occurring in the tube is controlled by a first order dynamics where only two parameters are involved: the characteristic's time linked to the erosion rate and the stress shear threshold for which erosion begins to develop. (Author) 5 refs.

  9. Taller de Química experimental: una mirada más allá del tubo de ensayo

    OpenAIRE

    Kozubsky, L.; Canestro, E.; Aloy, Mabel Rosa

    2009-01-01

    El taller consiste en una propuesta de trabajo grupal entre los alumnos y el coordinador docente en el que se emplean las metodologías que ayuden a aprender a pensar, aplicar conocimientos previamente adquiridos y descubrir nuevos. Es una propuesta abierta que conjuga trabajo con creatividad y cierta dosis lúdica, haciendo de la clase una experiencia activa donde se construye, intercambia y recrea con espacio para imaginar, equivocarse, ensayar, reflexionar. Así se desarrolló un taller optati...

  10. Identificación rápida de los serotipos del virus del dengue mediante la reacción en cadena de la polimerasa

    OpenAIRE

    DOMÍNGUEZ, DELFINA ROSARIO; SUÁREZ MORÁN, CARLOS MANUEL; RODRÍGUEZ ROCHE, ROSMARI; SOLER NODARSE, MARITZA; GUZMÁN TIRADO, MARÍA G

    1996-01-01

    Se emplearon 4 juegos de cebadores que permitieron la amplificación de una secuencia nucleotídica con talla única para cada uno de los serotipos del virus del dengue mediante la reacción en cadena de la polimerasa (RCP), con un método que consistió de extracción del ácido ribonucleico (ARN) de sobrenadante de cultivos celulares infectados, transcripción reversa - reacción en cadena de la polimerasa (TR-RCP), todo lo cual pudo ser completado en aproximadamente 7 horas, en un simple tubo. La ta...

  11. Aspectos morfométricos do tubo digestório de Roeboides xenodon e Orthospinus franciscensis

    Directory of Open Access Journals (Sweden)

    José Fernando Marques Barcellos

    2014-06-01

    Full Text Available http://dx.doi.org/10.5007/2175-7925.2014v27n3p139 Roeboides xenodon (dentudo e Orthospinus franciscensis (piaba-facão são peixes teleósteos de pequeno porte com hábitos alimentares onívoros. Com o objetivo de estudar a morfologia do tubo digestório exemplares de O. franciscensis (n=25 e de R. xenodon (n=16 foram coletados na bacia do rio São Francisco, represa de Três Marias – MG, e fixados em formol a 4%. Em ambas as espécies, o esôfago curto teve início na região cefálica e, após o septo transverso, continuou na cavidade peritoneal até à primeira região do estômago. Em R. xenodon, o esôfago apresentou pregas primárias espessas, estreitas e dispostas longitudinalmente, separadas por sulcos profundos e bordas livres e retas e pregas secundárias entre estas. Em O. franciscensis, o esôfago apresentou pregas primárias espessas e largas, longitudinais, sem sulcos profundos, mas com bordas livres e poucas anastomoses. O estômago é do tipo cecal, em “Y”. Os intestinos apresentaram duas porções: a anterior, mais longa e circunvoluta e a posterior, curta e linear. O início do intestino posterior foi demarcado pela alteração abrupta do padrão da mucosa. O esfíncter anal delimitou posteriormente o tubo digestório. O tubo digestório de ambas as espécies é completo e as adaptações tróficas encontradas no aparelho digestório são condizentes com o hábito alimentar carnívoro.

  12. Caracterização hidráulica de tubos porosos oriundos de pneus reciclados utilizados em irrigação subsuperficial

    Directory of Open Access Journals (Sweden)

    Marinaldo F. Pinto

    2014-11-01

    Full Text Available Mesmo diante do apelo ecológico pelo reaproveitamento de resíduos, os produtos de irrigação, como é caso de tubos porosos oriundos de pneus reciclados, devem ser avaliados quanto à sua viabilidade técnica. A caracterização hidráulica é um dos requisitos necessários para tal finalidade além de fornecer dados essenciais ao dimensionamento de sistemas de irrigação. Diante do exposto objetivou-se caracterizar tubos porosos quanto aos fatores perda de carga, vazão em função da pressão e variação de vazão. Foram utilizadas cinco amostras de tubo para determinação da perda de carga e oito para a determinação da curva vazão-pressão e do coeficiente de variação, sendo ensaiados sete níveis de pressão. A perda de carga foi determinada com tubo impermeabilizado e com distribuição de vazão para diferentes vazões. O tubo poroso apresentou coeficiente de variação de vazão em torno de 5%, considerado resultado satisfatório. O modelo potencial não se ajustou aos dados da curva característica vazão-pressão. Os fatores de atrito e de redução de perda de carga apresentaram comportamento divergente da literatura em que outros fatores, como a variação do diâmetro, devem ser estudados com maiores detalhes.

  13. Industria y peronismo: la fábrica de tubos de SIAM Di Tella SA (1948-1955

    Directory of Open Access Journals (Sweden)

    Rougier, Marcelo

    2008-01-01

    Full Text Available Depois da Segunda Guerra Mundial, o Estado argentino desenvolveu uma série de grandes empreendimentos na área de energia e a construção de oleodutos e gasodutos. Para fazer frente a essa demanda, uma tradicional empresa argentina, SIAM Di Tella, iniciou a fabricação de tubos sem costura, em 1948. Mas a nova empresa não seria muito exitosa durante os anos do peronismo, como conseqüência das deficiências que se apresentaram no funcionamento da máquina destinada a fabricar canos de grande diâmetro, o que a obrigou a diversificar sua produção

  14. UNILATERAL ACTINOMYCOTIC TUBO-OVARIAN ABSCESS COMPLICATED WITH CEREBRITIS – A CASE REPORT

    Directory of Open Access Journals (Sweden)

    Marina Jakimovska

    2018-02-01

    Full Text Available Background: Tuboovarian abscess is a serious complication of pelvic inflammatory disease. Pelvic ac- tinomycosis may correlate with long term use of intra-uterine device (IUD, but is uncom- mon cause of inflammation, except in postmenopausal IUD users.1, 2 Tuboovarian abscess complicated with cerebritis is relatively uncommon condition. Methods: We present a rare case of a 56-years-old woman with IUD, developing tuboovarian abscess that complicated with cerebritis. Twenty days before admittance to the Gynecologic clinic, she complained of fatigue and nausea, anorexia, vomiting and diarrhea. After an initial improvement for 5 days her symptoms recurred, profounded with sweating and fever up to 40 °C, leg weakness and walking difficulties, and weight loss. In that condition she was presented to our emergency room. There was no history of chronic disease. The patient had an IUD for the past 30 years. On physical examination the abdomen was tender, but without signs of peritoneal irritation. Laboratory studies revealed elevated CRP (107 mg/L, ESR (65mm/h and normal number of leukocytes (7.8 × 109/L. Ultrasound showed 8x4 cm left infraumbilical septated mass suspect for tubo-ovarian abscess.. She was hospitalized, IUD was removed and Metronidazol, Ciprofloxacin and Gentamycin were started parenterally. Tumor markers were negative. On the next day she developed neurologic symptoms with blindness and left-hemiparesis. MR angiography and CT of the head revealed local brain edema, suspect for cerebritis. Although the laboratory findings of inflammation were de- creasing, we changed the antimicrobial therapy with Cefotaxime and Kloksacilin (Orbenin instead of Metronidazol and Ciprofloxacin because of better blood-brain barrier transport. Cerebrospinal fluid tests for HSV, neurotropic viruses, malignant cells, TBC, echinoccocus, toxoplasmosis, cysticercosis, pathogenic bacteria, fungi, TILR2, and TNF alfa were nega- tive. A brain biopsy was preformed and

  15. Los tubos de hueso de la Cova de L'Or (Beniarrés, Alicante. Instrumentos musicales en el Neolítico Antiguo de la Península Ibérica

    Directory of Open Access Journals (Sweden)

    Martí Oliver, Bernat

    2001-12-01

    Full Text Available Not Available.

    [es] Como parte de la cultura material del Neolítico antiguo se presenta el conjunto de los tubos de hueso de la Cova de l´Or (Beniarrés, Alicante, en su mayor parte fabricados sobre ulnas de aves. El examen de las huellas de uso, los paralelos arqueológicos y etnográficos, y la reconstrucción experimental conducen a su identificación como instrumentos musicales del tipo flauta de Pan, o siringas monocálamas. Su presencia en distintos contextos y cronologías, incluyendo otros yacimientos del Neolítico peninsular, muestran la generalización de este instrumento musical. En la Cova de l´Or la representación de una danza en uno de sus vasos, realizada mediante impresiones cardiales, incide en la importancia de la música y del mundo religioso, tal como se desprende del arte rupestre Macroesquemático y de sus paralelos cerámicos. [fr] Les tubes en os de la Cova de L´Or (Beniarrés, Alicante. Instruments de musique du Néolithique Ancien de la Péninsule Ibérique. Sont présentés dans cet article les tubes en os provenant de la culture matérielle du Néolithique ancien de la Cova de l'Or (Beniarrés, Alicante, fabriqués pour la plupart sur des radius d'oiseaux. L´examen des stigmates d'utilisation, les parallèles archéologiques et ethnographiques, ainsi que la reconstitution expérimentale permettent de les assimiler à des instruments de musique du type flûtes de Pan, ou syrinx monocalames. Leur présence dans différents contextes et chronologies, en incluant ici d'autres gisements du Néolithique péninsulaire, sont des indices évidents de la généralisation de cet instrument musical. La représentation d'une danse par impressions cardiales sur l'un des vases de la Cova de l'Or trahit l'importance de la musique et du monde religieux, tel que cela transparaît dans l'art rupestre Macroschématique et dans la céramique.

  16. Detecting and classifying faults on transmission systems using a backpropagation neural network; Deteccion y clasificacion de fallas en sistemas de transmision empleando una red neuronal con retropropagacion del error

    Energy Technology Data Exchange (ETDEWEB)

    Rosas Ortiz, German

    2000-01-01

    Fault detection and diagnosis on transmission systems is an interesting area of investigation to Artificial Intelligence (AI) based systems. Neurocomputing is one of fastest growing areas of research in the fields of AI and pattern recognition. This work explores the possible suitability of pattern recognition approach of neural networks for fault detection and classification on power systems. The conventional detection techniques in modern relays are based in digital processing of signals and it need some time (around 1 cycle) to send a tripping signal, also they are likely to make incorrect decisions if the signals are noisy. It's desirable to develop a fast, accurate and robust approach that perform accurately for changing system conditions (like load variations and fault resistance). The aim of this work is to develop a novel technique based on Artificial Neural Networks (ANN), which explores the suitability of a pattern classification approach for fault detection and diagnosis. The suggested approach is based in the fact that when a fault occurs, a change in the system impedance take place and, as a consequence changes in amplitude and phase of line voltage and current signals take place. The ANN-based fault discriminator is trained to detect this changes as indicators of the instant of fault inception. This detector uses instantaneous values of these signals to make decisions. Suitability of using neural network as pattern classifiers for transmission systems fault diagnosis is described in detail a neural network design and simulation environment for real-time is presented. Results showing the performance of this approach are presented and indicate that it is fast, secure and exact enough, and it can be used in high speed fault detection and classification schemes. [Spanish] El diagnostico y la deteccion de fallas en sistemas de transmision es una area de interes en investigacion para sistemas basados en Inteligencia Artificial (IA). El calculo neuronal

  17. Caracterização hidráulica do tubo gotejador Hidrodrip II Hydraulic characterization of the integral dripline Hidrodrip II

    Directory of Open Access Journals (Sweden)

    Allison Magno de Sousa Oliveira

    2000-12-01

    Full Text Available O objetivo, com este trabalho realizado em laboratório, foi estudar as características hidráulicas do tubo gotejador Hidrodrip II, 2,3 L h-1, cujos emissores, inseridos nos tubos durante o processo de fabricação e espaçados a 0,3 m, apresentam formato tipo labirinto. Submeteram-se os tubos a diferentes pressões, para determinação das características hidráulicas: relação vazão-pressão dos emissores e coeficiente de variação de fabricação; também, avaliou-se o efeito da temperatura na vazão dos gotejadores. Os emissores apresentaram regime de fluxo turbulento (x = 0,51 e valor médio de 1,49% para o coeficiente de variação de fabricação, enquanto a variação de temperatura, de 30 a 60 ºC, reduziu a vazão dos gotejadores, em aproximadamente 1,75%.This study was carried out in laboratory with the objective of analizing the hydraulic characterization of the integral drip tape Hidrodrip II, 2.3 L h-1, whose emitters are spaced at 0.3 m and inserted in the tubes during the manufacture process. The tubes were submitted to several pressures to determine the hydraulic characteristics: discharge-pressure relation of emitters and the manufacturing variation coefficient. The temperature effect in the emitter discharge was also evaluated. The discharge exponent calculated indicates that the emitter has a turbulent flow and the mean manufacturing variation coefficient of 1.49%. The emitter discharge decreased only 1.75% as the temperature increased from 30 to 60 ºC.

  18. Caracterización de comunidades microbianas asociadas a depósitos de minerales secundarios en tubos de lava y minas de agua

    OpenAIRE

    García-Sánchez, A. M.

    2016-01-01

    La presente tesis doctoral representa un trabajo multidisciplinar, donde confluyen diversas especialidades biológicas, geoquímicas y mineralógicas, mediante la realización de un estudio geomicrobiológico exhaustivo de los ambientes de estudio. Los objetivos específicos planteados son los siguientes: 1. Conocer la diversidad de comunidades microbianas subterráneas asociadas a depósitos de minerales secundarios recogidos en minas de agua excavadas en granito y tubos de lava de diferentes ...

  19. Evaluación de extractos vegetales para el control de la broca del café (Hypothenemus hampei, ferrari)

    OpenAIRE

    Niño Osorio, Jaime; Correa N., Yaned Milena; Mosquera M., Oscar M.; Bustamante Peláez, Angélica María

    2007-01-01

    Este trabajo describe la evaluación por antibiosis de la actividad antibroca de 21 extractos metanólicos de las plantas recolectadas en la Reserva Natural Bremen-La Popa (Quindío). Los bioensayos se realizaron bajo condiciones controladas (23 ± 3 ºC; 75 ± 5 % H.R.), utilizando como unidad experimental (UE) un tubo eppendorf al interior del cual se transfirió un grano de café pergamino impregnado del respectivo extracto a 1000 mg/L y una hembra adulta de broca. Se hicieron 90 UE por cada extra...

  20. Neural networks

    International Nuclear Information System (INIS)

    Denby, Bruce; Lindsey, Clark; Lyons, Louis

    1992-01-01

    The 1980s saw a tremendous renewal of interest in 'neural' information processing systems, or 'artificial neural networks', among computer scientists and computational biologists studying cognition. Since then, the growth of interest in neural networks in high energy physics, fueled by the need for new information processing technologies for the next generation of high energy proton colliders, can only be described as explosive

  1. Multiple experimental approaches of immunotoxic effects of mercury chloride in the blue mussel, Mytilus edulis, through in vivo, in tubo and in vitro exposures

    International Nuclear Information System (INIS)

    Duchemin, Matthieu B.; Auffret, Michel; Wessel, Nathalie; Fortier, Marlene; Morin, Yves; Pellerin, Jocelyne; Fournier, Michel

    2008-01-01

    Biological impairments due to mercury discharge into the environment are now an issue of global concern. From the three forms of mercury found in aquatic ecosystems, the immunotoxic effects of mercury chloride were examined in the model animal, the blue mussel. In order to investigate the toxic potency of this chemical, three exposure regimes were carried out: chronic exposure of groups of individuals, a new protocol 'in tubo' designed for sub-acute exposures of individuals, and acute exposures of target cells. Chronic exposure revealed significant immunotoxic effects after 7 days at 10 -6 M, while acute exposures showed significant inhibition of phagocytosis at 10 -4 M and 10 -3 M. In sub-acute exposures both circulating haemocytes and haemocyte mortality increased at 10 -4 M and 10 -3 M while phagocytosis and the clearance rate drew hormetic toxic effects on healthy individuals. These results suggest the use of the 'in tubo' design for bivalve toxicological individual studies. - HgCl 2 impairs the immune system of test-tube mussels

  2. Intensidad exportadora e interacción entre fortalezas del marketing mix: un análisis basado en redes neuronales artificiales || Export Intensity and Interaction between Marketing Mix: An Analysis based on Artificial Neural Networks

    Directory of Open Access Journals (Sweden)

    Gutiérrez-Villar, Belén

    2014-12-01

    Full Text Available Entre los factores determinantes de la actuación exportadora de las empresas, numerosos estudios han subrayado la relevancia del mix de marketing. Generalmente, la mayoría de los estudios abordan el análisis de las variables centrado en estrategias específicas, en particular fenómenos de estandarización-adaptación. El presente estudio analiza si existe un efecto interactivo de fortalezas generadas en las diferentes variables del mix de marketing que pueda asociarse a diferentes perfiles exportadores. Para ello, se ha empleado el algoritmo Extreme Learning Machine (ELM dentro de los procedimientos Perceptrón Multicapa (MLP de Redes Neuronales Artificiales (RNA. Asimismo, el análisis se combina con un novedoso procedimiento de análisis de sensibilidad desarrollado ad hoc para este estudio, el cual permite conocer los efectos individuales e interactivos de las variables predictoras sobre la variable dependiente en problemas clasificatorios de naturaleza dicotómica. Los resultados obtenidos nos permiten corroborar la existencia de los efectos interactivos postulados, poniendo al mismo tiempo de manifiesto la utilidad de las RNA y del análisis de sensibilidad propuesto para la investigación en el área de marketing y, específicamente, para los estudios de internacionalización de empresas. || Among the determining factors in export activity, many studies have highlighted the relevance of the marketing mix. Generally, the majority of them use a variables analysis to focus on specific strategies, in particular, standardized-adaptations. This paper analyzes if there is an interactive effect of strength generated in different variables of the marketing mix that can be associated with different export profiles. The Extreme Learning Machine (ELM algorithm has been used within the Multilayer Perceptron (MLP of Artificial Neural Networks (ANN. In addition, the analyses combine a novel approach for sensitivity analysis developed ad hoc for this

  3. Reprogramación del polen a embriogénesis inducida por estrés: identidad celular, muerte celular programada y papel de la metilación de DNA

    OpenAIRE

    Solís, María Teresa

    2012-01-01

    El desarrollo del grano de polen es un proceso estrictamente regulado a nivel génico que conduce a la formación de un organismo haploide, el gametofito masculino o grano de polen, cuyas células poseen una alta especialización, necesaria para su importante función en la germinación del tubo polínico y doble fecundación de las plantas con flores. Mediante la aplicación de un tratamiento de estrés in vitro en la etapa adecuada del desarrollo, concretamente en la fase de microspora...

  4. Análise numérica da pressão de ruptura de tubos à base de borracha e cordonéis poliméricos

    Directory of Open Access Journals (Sweden)

    Maikson Luiz Passaia Tonatto

    2015-02-01

    Full Text Available Este trabalho tem como objetivo estudar o efeito de cordonéis de poliéster, poliamida, poliaramida e híbrido poliamida/poliaramida como reforço de elastômeros utilizados na fabricação de mangotes. O comportamento do tubo elastomérico reforçado com cordonéis sob pressão interna foi simulado com análise por elementos finitos (FEA utilizando-se elementos chamados reinforcement bars. Foram realizados ensaios para se obter as propriedades em tração dos cordonéis para alimentar o modelo. O cordonel de poliaramida apresentou a maior tensão de ruptura, o de poliamida maior deformação na ruptura, e o híbrido apresentou valores intermediários. O critério de falha adotado para o tubo consistiu na análise do nível de carga no cordonel. Foram avaliadas, principalmente, a pressão e a deformação de ruptura do tubo elastomérico simulado frente à variação do ângulo de orientação dos cordonéis. Os resultados mostraram que ângulos próximos a 55° tornam o tubo mais resistente porém menos rígido no sentido longitudinal.

  5. Memoria tècnica de la implementación del sistema de tratamiento externo de efluentes en papelera nacional s.a

    OpenAIRE

    Lozano Bravo, Juan; Wiesner Falconi, Ignacio

    2009-01-01

    Este proyecto se desarrollará en la Planta Industrial de PAPELERA NACIONAL S.A., empresa agro-industrial localizada en el Cantón Marcelino Maridueña Provincia del Guayas. Dedicada a la fabricación de papel Kraft, (Corrugado Medio, Extensible, y Test Liner) y sus derivados (Sacos de Papel Extensible para la Industria Azucarera y Cementera) y tubos Espiralados de cartón. La presente Tesis trata sobre los proyectos que se implementaron en Papelera Nacional S.A. a partir del, año 1998, tendie...

  6. Hepatitis inmune temprana en el curso del síndrome de Sjögren en pediatría

    OpenAIRE

    Baar Z., Alejandro; Harris D., Paul; Talesnik G., Eduardo; Duarte G. de C., Ignacio

    1999-01-01

    La hepatitis inmune corresponde a una enfermedad necroinflamatoria del hígado, de causa desconocida, asociada a la presencia de autoanticuerpos circulantes. Puede presentarse aisladamente, o en asociación a otras enfermedades autoinmunes. Entre estas, destaca el síndrome de Sjögren, que compromete preferentemente a las glándulas salivales, aunque puede afectar a cualquier segmento del tubo digestivo, especialmente el hígado. Reportamos el caso de una niña de 12 años de edad, portadora de Sínd...

  7. O tubo de silicone como dreno torácico em eqüinos The silicon tube when used as a thoracic drain in horses

    Directory of Open Access Journals (Sweden)

    Raquel Yvonne Arantes Baccarin

    2002-10-01

    Full Text Available O tórax agudo possui ocorrência comum em eqüinos, e é responsável por alta mortalidade. Diante disso, o aprimoramento dos meios de tratamento certamente contribuirá para o maior índice de sobrevivência desses animais. Para tanto, este estudo teve a finalidade de avaliar: a complacência, capacidade de drenagem e a radiopacidade de tubo de silicone quando utilizado como dreno torácico em eqüinos e, as possíveis alterações causadas nas variáveis fisiológicas, no hemograma e no líquido pleural. O tubo de silicone foi introduzido na cavidade pleural de 10 eqüinos hígidos através de trocarte, mediante sedação dos animais e anestesia local. Após introdução e posicionamento, o tubo foi conectado a equipo de infusão e tampado por torneira de três vias. Avalioaram-se as variáveis fisiológicas dos animais, analisaram-se o hemograma, o fibrinogênio plasmático e o líquido pleural durante 15 dias. Os dados obtidos foram confrontados estatisticamente pela análise de variância. Concluiu-se que o tubo de silicone permite drenagem satisfatória; mantém sua consistência inalterada na presença do líquido pleural; é radiopaco ao exame radiográfico e é passível de alterar sua complacência na presença de vácuo.The acute thorax syndrome is common in horses and has a high mortality rate. The development of more efficient treatment regimens will certainly account for an increased number of successful outcomes. The purpose of this research was to evaluate the silicon tube’s complacency, draining ability and radiopacity when used as a thoracic drain in horses. Changes in physiologic parameters, blood cell count and pleural fluid were also investigated. Ten horses of different breeds, body weight and age were used and the silicon tube was placed in the pleural cavity by means of a trocar, with the horse under sedation and local anesthesia. Following introduction and placement in the ventral portion of the cavity, the tube was

  8. Multichannel time-analyser with an electrostatic memory tube; Analyseur en temps a plusieurs canaux, avec memoire a potentioscopes; Mnogokanal'nye vremennye analizatory s pamyat'yu na potentsialoskopakh; Analizador multicanal de tiempo con tubo de memoria electrostatico

    Energy Technology Data Exchange (ETDEWEB)

    Ignat' ev, K G; Kirpichnikov, I V; Sukhoruchkin, S I

    1962-04-15

    The Academy of Sciences of the USSR has built two multichannel time-analysers with an LN-4 electrostatic memory tube for pulse analysis. These analysers are at present being used for various kinds of measurements; they have the following characteristics: Number of channels - 1024 and 2048, Channel time width - from 0.2 {mu}s upwards, Channel capacity - 4096 pulses and 1024 pulses, Analyser trigger frequency - up to 1000 per second, Pulse load - up to 1000 pulses per second. Measurement results are given by the analysers in the form of graphs and numerical data on perforated cards. (author) [French] A l'Institut de physique theorique et experimentale de l'Academie des sciences de l'Union sovietique, on a construit deux analyseurs d'impulsions en temps, a plusieurs canaux, avec memoire a potentioscopes du type LN-4. A l'heure actuelle ils sont employes pour diverses mesures; leurs caracteristiques sont les suivantes: Nombre de canaux - 1024 et 2048 respectivement, Largeur des canaux en temps-egale ou superieure a 0,2 {mu}s Capacite des canaux - 4096 et 1024 impulsions Frequence de declenchement maximum des analyseurs - 1000 fois par seconde Charge maximum - 1000 impulsions par seconde. Les resultats des mesures sont communiques par les analyseurs sous forme de graphiques et de donnees numeriques sur cartes perforees. (author) [Spanish] En el Instituto de Fisica Teorica y Experimental de la Academia de Ciencias de la Union Sovietica se han construido dos analizadores multicanales de tiempo con un tubo de memoria electrostatico LN-4 para el analisis de impulsos. Estos analizadores, que se utilizan actualmente para efectuar diversos tipos de mediciones, tienen las siguientes caracteristicas: Numero de canales: 1024 y 2048, Anchura de los canales: a partir de 0,2 {mu}s, Capacidad de los canales: 4096 y 1024 impulsos, Frecuencia de disparo del analizador: hasta 1000 por segundo, Carga: hasta 1000 impulsos/s. Los analizadores expresan los resultados de las mediciones en

  9. Estudio de la viabilidad de fabricación de un sistema codo (fundición inoxidable ferrítica, GX 260 Cr27-tubo composite (Incolloy 800 HT+Stal 2465 solidario por fusión

    Directory of Open Access Journals (Sweden)

    Gutiérrez de Solabarría, S.

    1995-10-01

    Full Text Available Flying ashes captured by ciclones in the experimental plant for combustion in pressure fluid bed, in Escatrón Power Plant (Zaragoza, Spain, circulate through the gas cleaning system and are evacuated by means of pneumatic transport. The temperature of these ashes is aprox. 800 °C and the relative pressure is up to 8 negative bars relating the outdoor pressure of the transport pipe. The configuration of the pneumatic transport lines is Incolloy 800 HT quality composite tubes lined with Stal 2465 in straight stretches. Regarding direction changes, ferritic stainless casting, quality GX 260 Cr 27 elbows are used. The aim of this work is to study the possibility of manufacturing a solidary system by means of melting between the ferritic stainless casting elbow and the composite pipe.

    Las cenizas volantes captadas por ciclones en la planta experimental de combustión en lecho fluido a presión, de la central térmica de Escatrón (Zaragoza, circulan por el sistema de depuración de gases y son evacuadas mediante transporte neumático. Estas cenizas se encuentran a una temperatura aproximada de 800 °C y a una presión relativa de hasta 8 bares negativos con respecto a la presión en el exterior de la tubería de transporte. Para configurar las líneas de transporte neumático, se utilizan en los tramos rectos tubos composite de calidad Incolloy 800 HT recubiertos interiormente de material Stal 2465. Para los cambios de dirección, se utilizan codos de fundición inoxidable ferrítica de calidad GX 260 Cr 27. El objetivo del presente trabajo es estudiar la viabilidad de fabricación de un sistema solidario por fusión entre el codo de fundición inoxidable ferrítica y la tubería composite.

  10. Fundamentos del ácido fólico en la prevención primaria farmacológica de defectos congénitos Foundations of folic acid in the primary pharmacological prevention of congential defects

    Directory of Open Access Journals (Sweden)

    Roberto Lardoeyt Ferrer

    2005-04-01

    Full Text Available El ácido fólico fue descubierto en 1945 por los laboratorios Lederle, y desde entonces existe una gran variedad de derivados de esta vitamina, que se agrupan bajo el nombre común de folatos. Es en la APS donde se promueve la salud de la mujer y de su futura descendencia a través de la consulta de riesgo preconcepcional. Una de las acciones promotoras de la salud más importante de la asistencia preconcepcional, es la prevención de los defectos congénitos en la descendencia a través de la suplementación periconcepcional con folatos. El déficit de ácido fólico puede deberse tanto a factores genéticos como ambientales. Con el objetivo de incrementar los conocimientos de los profesionales de la salud que laboran en la atención médica a la mujer en edad reproductiva, se realizó una revisión del tema, en la que se tratan los fundamentos científicos que demuestran la importancia del uso de esta vitamina en la prevención de problemas congénitos como los defectos del tubo neural (DTN, síndrome de Down y de otras anomalías asociadas al déficit de este compuesto vitamínico.Folic acid was discovered in 1945 by Lederle laboratories and since then, there is a great variety of derivates of this vitamin that are grouped under the name of folates. It is in PHC where the health of woman and of her future off-spring is promoted through the office of preconceptional risk. One of the most important health promoting actions of preconceptional assistance is the prevention of the congenital defects in the off-spring by the periconceptional supplementation with folates. The deficit of folic acid may be caused by genetical and environmental factors. In order to increase the knowledge of the health professionals giving medical attention to women at gestational age, a review of this topic was made and the scientific foundations showing the importance of the use of this vitamin in the prevention of congenital defects, such as the neural tube defects

  11. Neural Networks

    International Nuclear Information System (INIS)

    Smith, Patrick I.

    2003-01-01

    Physicists use large detectors to measure particles created in high-energy collisions at particle accelerators. These detectors typically produce signals indicating either where ionization occurs along the path of the particle, or where energy is deposited by the particle. The data produced by these signals is fed into pattern recognition programs to try to identify what particles were produced, and to measure the energy and direction of these particles. Ideally, there are many techniques used in this pattern recognition software. One technique, neural networks, is particularly suitable for identifying what type of particle caused by a set of energy deposits. Neural networks can derive meaning from complicated or imprecise data, extract patterns, and detect trends that are too complex to be noticed by either humans or other computer related processes. To assist in the advancement of this technology, Physicists use a tool kit to experiment with several neural network techniques. The goal of this research is interface a neural network tool kit into Java Analysis Studio (JAS3), an application that allows data to be analyzed from any experiment. As the final result, a physicist will have the ability to train, test, and implement a neural network with the desired output while using JAS3 to analyze the results or output. Before an implementation of a neural network can take place, a firm understanding of what a neural network is and how it works is beneficial. A neural network is an artificial representation of the human brain that tries to simulate the learning process [5]. It is also important to think of the word artificial in that definition as computer programs that use calculations during the learning process. In short, a neural network learns by representative examples. Perhaps the easiest way to describe the way neural networks learn is to explain how the human brain functions. The human brain contains billions of neural cells that are responsible for processing

  12. Evolvable synthetic neural system

    Science.gov (United States)

    Curtis, Steven A. (Inventor)

    2009-01-01

    An evolvable synthetic neural system includes an evolvable neural interface operably coupled to at least one neural basis function. Each neural basis function includes an evolvable neural interface operably coupled to a heuristic neural system to perform high-level functions and an autonomic neural system to perform low-level functions. In some embodiments, the evolvable synthetic neural system is operably coupled to one or more evolvable synthetic neural systems in a hierarchy.

  13. Determination of the concentration profile of chemical elements in superheater pipes; Determinacion del perfil de concentracion de elementos quimicos en tubos de sobrecalentadores

    Energy Technology Data Exchange (ETDEWEB)

    Aldape U, F; Aspiazu F, J [ININ, 52045 Ocoyoacac, Estado de Mexico (Mexico)

    1986-05-15

    This work has for object to determine the profile of concentration of chemical elements at trace level in a superheater pipe of Thermoelectric Plants using the X-ray emission spectroscopy technique induced by protons coming from the Accelerator of the Nuclear Center. In the X-ray detection, a Si Li detector was used. The technique was chosen because it allows a multielemental analysis, of high sensitivity and precision. The results can help to understand the problems that are had in the change of flexibility or of corrosion. This will be from utility to the Federal Electricity Commission (CFE). (Author)

  14. Comprobación de la posición del tubo endotraqueal mediante ecografía clínica

    OpenAIRE

    Díaz Águila, Héctor R

    2017-01-01

    Fundamento: La intubación traqueal es el segundo procedimiento invasivo más utilizado en pacientes graves. Se han utilizado varios métodos para la comprobación de la intubación traqueal de forma satisfactoria, entre ellas la auscultación pulmonar, la capnografía, estudio radiológico y ecografía. Presentación de caso: Se presentó un caso que acudió al servicio de urgencias, por disnea intensa, se requirió atención en terapia intensiva y se realizó intubación rápida orotraqueal guiada por ecogr...

  15. Analysis of the design of an X-ray tube using Monte Carlo; Analisis del diseno de un tubo de rayos X mediante Monte Carlo

    Energy Technology Data Exchange (ETDEWEB)

    Pena V, J. D.; Sosa A, M. A.; Ceron, P. V.; Vallejo, M. A. [Universidad de Guanajuato, Division de Ciencias e Ingenierias, Loma del Bosque No. 103, Lomas del Campestre, 37150 Leon, Guanajuato (Mexico); Vega C, H. R., E-mail: jd.penavidal@ugto.mx [Universidad Autonoma de Zacatecas, Unidad Academica de Estudios Nucleares, Cipres No. 10, Fracc. La Penuela, 98060 Zacatecas, Zac. (Mexico)

    2017-10-15

    In this paper we present the Monte Carlo analysis of the X-rays produced by a rotating X-ray tube of the Siemens brand that is used in tomographs for clinical use. The work was done with the MCNP6 code with which the tube was modeled and the primary X-ray spectra produced during the interaction of monoenergetic electrons of 130 keV were calculated. The X-ray spectra were obtained by varying some parameters such as: the angle of the anode (15 to 20 degrees), the type of target (Tungsten, Molybdenum and Rhodium) and the thickness of the filter (3, 5, 10 and 15 mm). In order to have a good statistic 10{sup 7} stories were used. Though the estimators f2 and f5 the X-ray spectra and the total fluencies were estimated. This information will be used to calculate the dose absorbed in the lens and the thyroid gland in patients undergoing radio diagnosis procedures. (Author)

  16. Patología infecciosa: vulvovaginitis, enfermedades de transmisión sexual, enfermedad inflamatoria pélvica, abscesos tubo-ováricos Infectious pathology: vulvovaginitis, sexually transmitted diseases, pelvic inflammatory disease, tubo-ovarian abscesses

    OpenAIRE

    M. Ibarrola; J. Benito; B. Azcona; N. Zubeldía

    2009-01-01

    Las enfermedades de transmisión sexual son aquellas en las que la principal vía de infección es el contacto íntimo. Son numerosas las pacientes que acuden a urgencias por esta causa, tanto por la clínica como por las implicaciones sociales. Los síntomas más frecuentes son dolor abdominal bajo, sangrados vaginales, o flujo vaginal excesivo o molesto. Las vulvovaginitis son uno de los problemas principales en la práctica clínica diaria del ginecólogo. La úlcera genital cuya etiología principal ...

  17. Descripción histológica del oviducto de Caiman crocodilus fuscus

    Directory of Open Access Journals (Sweden)

    Ramiro Elduardo Bahamón Vanegas

    2000-01-01

    Full Text Available Se describe la histología del oviducto de 27 hembras de Caiman crocodilus fuscusdurante tresetapas del ciclo reproductivo anual (previtelogénesis, vitelogénesis y gravidez por microscopíaóptica de alta resolución (MOAR y, en algunas regiones, por microscopía electrónica detransmisión (MET. Con ayuda de pruebas histoquímicas (ácido peryódico de Schiff P.A.S. yazul de Alcian A.A., pH 2,4, se aproxima la función de cada una de las regiones. El oviductode C. c. fuscuses un órgano pareado, funcional, en forma de tubo muy contorneado. Desdeel extremo proximal al caudal se reconocen histológicamente las siguientes regiones:infundíbulo anterior, infundíbulo posterior, tubo, transición tubo-útero anterior, úteroanterior, útero posterior y vagina. Tres capas conforman la pared del oviducto: una externade revestimiento (serosa con células cúbicas bajas que no presentan cambios significativosa lo largo del ciclo reproductivo, una capa muscular longitudinal externa y circular internaque cambian según el estado reproductivo y la región, y una capa mucosa más interna. Lamucosa se hipertrofia en vitelogénesis y gravidez y está revestida por cuatro tipos de células:ciliadas, no ciliadas y secretoras PAS y AA positivas las cuales producen mucosubstanciasácidas o neutras que pueden lubricar la superficie de la mucosa y/o tomar parte de huevoen formación. Glándulas tubulares simples se encuentran en la mucosa del tubo y úteroanterior, presentan actividad secretora (PAS y AA negativa durante todo el ciclo y se ramifican en vitelogénesis y gravidez. En el útero posterior hay glándulas tubulares simples sinevidencia de secreción, las células glandulares son similares a las células del útero poste-rior de Alligator mississippiensisy a las células que transportan iones y material el dilución deloviducto de las aves (Gallus domesticus; estas glándulas no se describen en el oviducto de otrosreptiles y al parecer son únicas de

  18. Metamorfosis del aparato digestivo de larvas carnívoras de Ceratophrys cranwelli (Anura: Leptodactylidae

    Directory of Open Access Journals (Sweden)

    Ulloa Kreisel, Zandra E.

    2000-12-01

    Full Text Available Las larvas carnívoras de Ceratophrys cranwelli presentan un tubo digestivo más corto que la mayoría de las larvas de anuros, tiene 6 veces la longitud del cuerpo del renacuajo y se caracteriza también por tener un estómago larval. El presente trabajo tiene como objetivo el determinar el grado de transformaciones en la cavidad bucofaríngea y tubo digestivo en larvas de esta especie durante la metamorfosis y comparar las estructuras digestivas estudiadas en otras especies de Leptodactylidae de la subfamilia Ceratophryinae y especies con otros hábitos alimenticios. Carnivorous larvae from Ceratophrys cranwelli present a digestive tube shorter than most of the anuran larvae, have 6 times a tadpole’s body length and they are also characterized by the presence of a larval stomach. The aim of this work is determine the grade of transformations in the buccopharyngeal cavity and digestive tube during the metamorphosis in larvae of this species and compare the digestive structures studied in other species of Leptodactylidae of the subfamily Ceratophryinae and another species with different diets.

  19. Limits to the Recognizability of Flaws in Non-Destructive Testing Steam-Generator Tubes for Nuclear-Power Plants; Limitations de l'Efficacite de la Detection des Defauts par Essais Non Destructifs de Tubes de Bouilleurs pour Centrales Nucleaires; Predely ehffektivnosti nedestruktivnoj defektoskopii trub parogeneratorov yadernykh ehlektrostantsij; Limites para Distinguir los Defectos en el Ensayo No Destructivo de Tubo para Generadores de Vapor Destinados a Centrales Nucleares

    Energy Technology Data Exchange (ETDEWEB)

    Kuhlmann, A.; Adamsky, F. -J. [Technischer Ueberwachungs-Verein Reinland e.V., Cologne (Germany)

    1965-10-15

    -Verein' de Rhenanie qui a ete charge de surveiller et de controler la fabrication et le montage des bouilleurs, pour garantir que cet element de la centrale soit aussi exempt que possible de defauts. L'experience acquise dans l'execution de ces travaux peut etre tres utile pour la fabrication et le montage des bouilleurs de n'importe quel type de centrale nucleaire. Le memoire traite des limitations de l'efficacite des essais non destructifs de tubes de bouilleurs. Les auteurs discutent plus particulierement les essais ci-apres: a) Controle automatique par ultrasons de tubes droits dans l'usine de production; b) Controle combine, par ultrasons et par radiographie, de tubes coudes et de soudures; c) Autres controles non destructifs. (author) [Spanish] En la Republica Federal de Alemania se estan construyendo reactores nucleares con generadores de vapor situados en el interior del tanque de presion. Las caracteristicas de este modelo dificultan considerablemente la reparacion de los tubos del generador que puede llegar a paralizar la central nuclear por largos periodos. Como es bien sabido, muchas de las dificultades para mantener en funcionamiento las centrales nucleares de tipo clasico provienen de averias en los tubos del generador de vapor. Por ello, y teniendo tambien en cuenta como razon no menos importante el elevado costo total de esos reactores, es preciso construir los generadores de vapor de tal manera que el factor carga de la central sea lo mas elevado posible. El Technischer Ueberwachungs-Verein Rheinland se encarga de dirigir e inspeccionar la fabricacion y la construccion de generadores de vapor para que esa parte de las instalaciones carezca en lo posible de defectos. La experiencia adquirida a ese respecto ofrece ademas interes para la fabricacion y construccion de los generadores de vapor que se destinan a las centrales nucleares en general. En la presente memoria se examinan los limites de rendimiento del ensayo no destructivo de los tubos para generadores

  20. Estudio de un vórtice de Rankine con velocidad axial discontinua en un tubo infinito

    OpenAIRE

    Gonzalez, R; Vigh, C.D

    2016-01-01

    En este trabajo se muestra que un vórtice de Rankine confinado con flujo axial uniforme, posee sólo modos neutros aun cuando la velocidad axial sea discontinua en la interfase rotacional-irrotacional. Esta discontinuidad produce un curvamiento de las ramas inferiores de la relación de dispersión de tal forma que cortan al eje del número de onda con pendiente negativa, es decir velocidad de grupo negativa. Este resultado apoya la idea original de que el fenómeno de Vortex Breakdown se podría e...

  1. Non-Destructive Testing Methods Applied to Multi-Finned SAP Tubing for Nuclear-Fuel Elements; Essais Non Destructifs de Gaines a Ailettes, en Poudre d'Aluminium Frittee, pour Elements Combustibles; Nedestruktivnye metody ispytaniya rebristykh trub iz spechennogo alyuminikiog'o poroshka dlya yadernykh toplivnykh ehlementov; Metodos de Ensayo No Destructivo Aplicados a Tubos de SAP con Aletas Multiples Destinados a Elementos Combustibles

    Energy Technology Data Exchange (ETDEWEB)

    Lund, S. A. [Danish Central Welding Institution, Copenhagen (Denmark); Knudsen, P. [Danish Atomic Energy Commission, Research Establishment, Risoe (Denmark)

    1965-09-15

    Energia Atomica de Dinamarca ha emprendido el estudio de un reactor de potencia con refrigerante organico y moderador de agua pesada. Los correspondientes elementos combustibles consisten en haces de 19 barras formadas por pastillas de dioxido de uranio sinterizado, encerradas en tubos de producto de aluminio sinterizado (SAP), de 2 m de longitud, provistos de aletas helicoidales. Para obtener condiciones optimas de transmision de calor y mantener la integridad del elemento combustible durante el funcionamiento del reactor, es necesario contar con tubos de muy alta calidad. Se citan dos ejemplos que ponen de manifiesto las estrechas tolerancias dimensionales adoptadas. Para asegurar una calidad adecuada de los tubos, se establecio un control de calidad muy estricto, basado en gran medida en la aplicacion de metodos no destructivos. Se describen en esta memoria las tecnicas desarrolladas para medir el espesor de pared y los diametros, y para descubrir defectos. La compleja seccion transversal, con 24 aletas, impide aplicar metodos ultrasonicos o de comentes de Foucault para medir el espesor de la pared. Por consiguiente, se desarrollo un calibre registrador de rayos beta, cuyo funcionamiento se basa en la atenuacion sufrida por la radiacion beta proveniente de una fuente de {sup 90}Sr colocada en el interior del tubo. Para el registro continuo del espesor de la pared del tubo con seccion transversal mas simple, de 12 aletas, se utiliza un metodo ultrasonico de resonancia por inmersion. Los diametros interno y externo (entre puntos de aletas) se registran de manera continua mediante calibres neumaticos rapidos. Las fallas se detectan mediante la tecnica de eco de impulsos ultrasonicos, y examinando los tubos con corrientes de Foucault. El metodo ultrasonico permite descubrir facilmente las fisuras transversales, pero hasta ahora ha sido imposible utilizarlo para la deteccion de defectos longitudinales. Por consiguiente, ademas del ensayo ultrasonico, se aplica el examen con

  2. Neural Networks

    Directory of Open Access Journals (Sweden)

    Schwindling Jerome

    2010-04-01

    Full Text Available This course presents an overview of the concepts of the neural networks and their aplication in the framework of High energy physics analyses. After a brief introduction on the concept of neural networks, the concept is explained in the frame of neuro-biology, introducing the concept of multi-layer perceptron, learning and their use as data classifer. The concept is then presented in a second part using in more details the mathematical approach focussing on typical use cases faced in particle physics. Finally, the last part presents the best way to use such statistical tools in view of event classifers, putting the emphasis on the setup of the multi-layer perceptron. The full article (15 p. corresponding to this lecture is written in french and is provided in the proceedings of the book SOS 2008.

  3. Espina bífida: prevención y abordaje actual de este trastorno

    OpenAIRE

    Santos Hernández, Susana de

    2016-01-01

    Con este trabajo lo que se pretende es contextualizar en primer lugar, las malformaciones congénitas y posteriormente y de forma más extensa, hablar de la espina bífida en concreto: definición, tipos y como tema principal, la prevención primaria y la actuación enfermera. Durante el desarrollo embrionario se produce el cierre del tubo neural en torno a las 6 semanas tras la concepción. Los llamados defectos del tubo neural (DTN) se producen como consecuencia de alteraciones en el cierre de ...

  4. Coste del kWh eólico generado en Cuba, a partir de datos de viento de una región de buenos potenciales eólicos // Cost of the kW h generated with wind energy in Cuba, analyzing the data of wind of a region of good potentials.

    Directory of Open Access Journals (Sweden)

    Deivis Avila - Prats

    2010-09-01

    Full Text Available La detección de defectos en tubos sometidos a presión interna es un aspecto poco estudiado. Unode los problemas a resolver es el modelado de los defectos, en particular los del tipo grieta cerrada.La dinámica de un tubo con un fluido interno a presión implica dificultades adicionales al problema.Se presentan los principios y las ecuaciones necesarias para poder modelar por el método de loselementos finitos la presencia de una grieta transversal parcial en un tubo de paredes delgadas envarios escenarios: vacío, con un fluido interno y con un fluido a presión. El análisis modal esempleado para determinar los cambios en los parámetros del modelo y valorar la influencia de lagrieta en los mismos. Se parte del experimento de S.M. Murigendrappa y S.K. Maiti, el efecto de lagrieta está representado por una reducción de la rigidez a la flexión del tubo en la zona de extensiónd, cuya extensión es determinada a partir del concepto de energía potencial de la deformación,planteado por A P. Bovsunovsky y V. V. Matveev.Palabras claves: grieta cerrada, análisis modal, tubos, elementos finitos._____________________________________________________________________________AbstractFail detection in pipes under internal pressure is a not enough studied matter. A main problem is faultmodeling, particularly the closed crack type. The dynamic of a pipe filled with a fluid under pressureimplies additional challenges. The equations and principles needed to obtain a finite elements modelof a partial transverse crack in a thin walled pipe are shown in different sceneries: empty, filled withfluid and filled with fluid under certain pressure. A modal analysis is performed to obtain the changesin modal parameters and crack influence. The result shows a good agreement with those obtained byS.M. Murigendrappa and S.K. Maiti. The crack is modeled trough a reduction of bending stiffness in areduced zone. Its extension is calculated using the principle of equal

  5. Morphometric identification of small mammal footprints from ink tracking tunnels in the Brazilian Cerrado Identificação morfométrica de pequenos mamíferos usando tubos de pegadas no Cerrado

    Directory of Open Access Journals (Sweden)

    Alexandre R. T. Palma

    2007-06-01

    Full Text Available An alternative method for identifying and inventorying rodents and marsupials inhabiting forests and grasslands of Brazilian Cerrado is presented and discussed. Ink tracking tunnels were designed according to the size of target species and used to build a reference collection of small mammal footprints composed of 1408 footprints belonging to 251 individuals from 30 species (21 rodents and nine marsupials. Sherman traps and ink tracking tunnels were used to conduct inventories in gallery forests. Footprints obtained in ink tracking tunnels were digitalized and compared with those in reference collection using Discriminant Analysis (DFA. DFA allowed good footprint differentiation, even among congeneric species. In DFA analysis, the first two axis were related to size and arboreality. The efficiency of ink tracking tunnels was higher (track-success = 31% than conventional trapping (trap-success = 14% in inventories. Ink tracking tunnels gave a good description of the small mammal community of gallery forest by detecting rodents and marsupials of different habits, including trap-shy species. This paper also discusses advantages and limitations of ink tracking tunnels use in inventories and ecological studies, and concludes that this technique can be efficient in long-term studies and in rapid inventories as a complementary technique for trapping.Um método alternativo de identificação e inventário de roedores e marsupiais de florestas e áreas abertas do Cerrado é apresentado e discutido. Os tubos de pegadas foram projetados de acordo com o tamanho das espécies alvo e usados para construir uma coleção de referência de pegadas de pequenos mamíferos formada por 1408 pegadas pertencentes a 251 indivíduos de 30 espécies (21 roedores e nove marsupiais. Armadilhas Sherman e tubos de pegadas foram usados para conduzir inventários em matas de galeria. As pegadas obtidas nos tubos foram digitalizadas e comparadas com as da coleção de refer

  6. ULTRASONIDO ENDOSCÓPICO EN PATOLOGÍAS DEL PÁNCREAS

    Directory of Open Access Journals (Sweden)

    LÁZARO ANTONIO ARANGO M., DR.

    2015-09-01

    En este artículo se revisarán algunos casos de enfermedades evaluadas con este método, que muestran por qué el EUS, es una herramienta clave para el médico de urgencias y de consulta externa, el internista, el cirujano, el médico del servicio hospitalario y el personal de salud en general, al momento de definir, clasificar y orientar el manejo de determinadas patologías en el tubo digestivo. El EUS es una importante ayuda y no debe ser extraña al personal médico, debe tenerla presente junto a las demás pruebas diagnósticas en patología pancreática. Se señalarán los aspectos más relevantes en cada caso y las indicaciones del EUS.

  7. Peces del Noroeste del Ecuador

    OpenAIRE

    Barriga, Ramiro

    1994-01-01

    La ictiofauna del occidente del Ecuador es poco conocida. Los peces del noroccidente son diferentes a los del suroccidente del Ecuador. 34 familias y 82 especies fueron colectadas que equivale al 11 % de las especies de peces continentales registradas en el Ecuador. Icteogeográficamente se sabe que la costa ecuatoriana posee dos provincias: la del Pacifico Norte y la del Guayas, se determinó que el límite de las dos provincias es el río Santiago ya que las especies del mencionado río so...

  8. Frecuencia del antígeno y aloanticuerpos del sistema Diego en donantes de sangre.

    Science.gov (United States)

    Góngora, Fernando B; Chiriboga-Ponce, Rosa F

    2018-01-01

    El sistema Diego es un sistema sanguíneo irregular involucrado de manera clínica en casos de enfermedad hemolítica del recién nacido y en reacciones postransfusionales, dentro de este sistema de han identificado a 22 antígenos eritrocitarios de los cuales el par Di a /Di b son los de mayor importancia por su potencial inmunogénico. Determinar la frecuencia del antígeno Di a y la identificación del aloanticuerpo en la población ecuatoriana. Se realizó un muestreo aleatorio simple y se testó mediante aglutinación en tubo la presencia o ausencia del antígeno y en metodología en gel la presencia del aloanticuerpo anti-Di a . se estableció una prevalencia del antígeno Di a del 25% frente a un 6.09% de aloinmunización por dicho antígeno en donantes de sangre ecuatorianos; no existieron diferencias significativas en la asociación de las variables, siendo estas independientes de la edad y procedencia del donante, sin embargo se pudo constatar que en Ecuador existe población portadora del antígeno Diego Di a y casos de aloinmunización por este sistema debidos probablemente a la incompatibilidad transfusional sea esta por vía maternofetal o por transfusiones de sangre. La distribución de la frecuencia de antígenos y aloanticuerpos del sistema Diego es casi uniforme dentro de la población de nuestro país, probablemente por ser un territorio con alto grado de mestizaje, por lo que es de vital importancia la implementación de la detección de este sistema sanguíneo y su inclusión dentro de los protocolos de detección de anticuerpos irregulares en los bancos de sangre de Ecuador. Copyright: © 2018 SecretarÍa de Salud

  9. Regurgitación y aspiración de contenido gástrico en pacientes sometidas a cirugía laparoscópica ginecológica con tubo laríngeo con succión

    Directory of Open Access Journals (Sweden)

    Juliana María Mendoza Villa

    2008-11-01

    Full Text Available

    OBJETIVO: determinar la incidencia de regurgitación y aspiración de contenido gástrico en pacientes sometidas a laparoscopia ginecológica (LG electiva bajo anestesia general, con la utilización del Tubo laríngeo con succión.

     

    DISEÑO: estudio clínico prospectivo, observacional y descriptivo.

     

    SITIO: Clínica del Prado, Medellín, Antioquia, Colombia.

     

    INTERVENCIONES: manejo de la vía aérea con Tubo laríngeo- S™ (TL-S™; VBM Medizintechnik, Sulz, Alemania.

     

    RUÍDO OCUPACIONAL EM ESTAÇÕES DE ÔNIBUS – ESTUDO DE CASO EM ESTAÇÕES TUBO – CURITIBA – PARANÁ - BRASIL

    Directory of Open Access Journals (Sweden)

    David Queiroz Santana

    2016-08-01

    Full Text Available O presente trabalho teve por objetivo investigar o nível de ruído ao qual o cobrador das estações de embarque e desembarque de passageiros das linhas expressas do sistema de transporte da cidade de Curitiba se encontra exposto durante sua jornada de trabalho. Toma-se para análise as estações-tubo localizadas nas avenidas Pe. Anchieta e Sete de Setembro, trechos de maior adensamento habitacional e de maior renda média da região sul da cidade.  As altas densidades e o perfil econômico produzem um maior fluxo de veículos leves o que colabora para o aumento dos níveis de ruído. De um total de 10 estações em que foram efetuadas medições do nível equivalente de ruído (Leq em intervalos de 10 minutos, observa-se conformidade acústica do ambiente de trabalho nas estações, quando consideradas as recomendações das normas nacionais NR – 15 (1992, NHO – 01 (1999 as quais legislam sobre o ruído ocupacional. Nas 10 amostras estudadas os níveis sonoros equivalentes medidos tem valores inferiores a 80 dB(A, nível sonoro que a partir do qual há a indicação de risco auditivo. Entretanto, sob as prescrições da norma brasileira que estabelece os padrões de ergonomia para o ambiente de trabalho NR – 17 esses ambientes caracterizam-se como desconfortáveis na totalidade das amostras, pois registram níveis sonoros equivalentes acima de Leq = 65 dB(A.

  10. The Economical Application of Non-Destructive Testing to Reactor Components, Especially Jacket Tubing; Avantages Economiques du Controle Non Destructif des Pieces de Reacteurs, Notamment des Tubes de Gainage; Ehkonomicheskoe primenenie nedestruktivnykh ispytanij dlya reaktornykh komponentov, v chastnosti obolochechnykh trub; Aplicacion en Condiciones Economicas de Ensayos No Destructivos a las Piezas de los Reactores, en Especial a los Tubos de Revestimiento

    Energy Technology Data Exchange (ETDEWEB)

    Renken, C. J. [Metallurgy Division Argonne National Laboratory Argonne, IL (United States)

    1965-10-15

    metodos de ensayo no destructivo para mantener la calidad del producto durante las diversas etapas del proceso y de indicar, a base de los resultados obtenidos, en cuales de esas etapas es mas probable que la pieza adquiera defectos. A menudo ocurre que el ensayo no destructivo de la pieza en las primeras etapas de su fabricacion no puede sustituirse, por la inspeccion de dicha pieza en forma acabada o semiacabada. Para demostrarlo se citan ejemplos, sobre todo relativos a los tubos para revestimiento del combustible y a las aplicaciones de los intercambiadores de calor. Se expone, en forma bastante circunstanciada, la aplicacion de los diversos metodos de ensayo no destructivo durante el desarrollo de un programa de produccion de tubos, y se comparan los costos de fabricacion y de inspeccion de algunas clases de tubos utilizadas para revestimiento por el Argonne National Laboratory. Aunque con esos procedimientos la inspeccion de las piezas acabadas tiene una importancia secundaria, no siempre puede eliminarsela enteramente. Se examina detenidamente el metodo economico de ensayo de placas y tubos, en especial de estos ultimos, refiriendose sobre todo a las piezas de acero inoxidable, zircaloy y ciertas aleaciones de metales refractarios. Con varios ejemplos queda demostrado que si bien el uso de la radiografia y de los agentes de penetracion puede ser titil o incluso constituir una parte imprescindible del ensayo, en general, por razones de Indole tecnica o economica, es preciso proceder a una inspeccion critica de los tubos delgados, ya sea por metodos ultrasonicos o electromagneticos. Se explica el campo de aplicacion de esos dos metodos en condiciones optimas y tambien la amplia zona de superposicion en que los resultados obtenidos con equipo de ambas clases, bien concebido y manejado, son esencialmente equivalentes. La indicacion falsa de defectos contribuye directamente a aumentar el costo de la pieza; por ello, se incluye una evaluacion de ese efecto pernicioso de

  11. Prevención y tratamiento actual del glaucoma

    Directory of Open Access Journals (Sweden)

    DR. P. José Manuel Díaz

    2010-11-01

    Full Text Available El glaucoma es la principal causa de ceguera no reversible en el mundo, afectando al 2% de la población. Actualmente se considera una neuropatía óptica, donde la presión intraocular juega un rol fundamental en la patogenia y las características del daño óptico producido. Con el tratamiento actual, se busca prevenir el daño en la estructura del nervio óptico, para preservar el campo visual, persiguiendo mantener la calidad de vida del paciente. Existen nuevos métodos imaginológicos que junto al examen clínico y campo visual, predicen daño y avance de enfermedad. Se incluyen en la comprensión de la patología la apoptosis y el concepto de neuroprotección. Nuevos fármacos buscan mantener una adecuada reducción en la presión intraocular sin fluctuaciones, evitando efectos adversos y mejorando la adherencia al tratamiento. Nuevas herramientas terapéuticas como la trabeculoplastía selectiva láser y nuevas cirugías como el implante de tubos de drenaje, aumentan las posibilidades de evitar la ceguera por glaucoma.

  12. Estudo das estratégias operacionais das empresas de tubos e conexões de PVC na indústria plástica joinvillense nos anos 90

    OpenAIRE

    Klug, Jonas Fernandes

    2001-01-01

    Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro Sócio-Econômico. Programa de Pós-Graduação em Economia Esta dissertação de mestrado, cujo título é Estudo das Estratégias Operacionais das Empresas de Tubos e Conexões de PVC na Indústria Plástica Joinvilense nos anos 90, focaliza determinados aspectos da competitividade industrial no atual contexto econômico, com base nos principais acontecimentos das décadas de 70, 80 e 90, a partir da problemática: O setor industria...

  13. Avaliação das tensões residuais em tubos de pequeno diâmetro soldados pelo processo TIG orbital Residual stress evaluation in small diameter pipes welded using orbital TIG process

    Directory of Open Access Journals (Sweden)

    George Luiz Gomes de Oliveira

    2009-06-01

    Full Text Available O objetivo desse trabalho é avaliar o efeito da soldagem TIG orbital sobre o nível de tensões residuais da junta, sobre a microestrutura resultante e sobre o aspecto superficial do cordão de solda, considerando os efeitos da energia de soldagem, do número de passes e do tipo de pulsação (corrente e rotação em tubos de pequeno diâmetro e contribuir para a análise de decisões de se aplicar ou não testes hidrostáticos ou TTPS. Os corpos de prova soldados com diferentes níveis de energia, pulsação e número de passes foram submetidos à medição de tensões residuais em um difratômetro de Raios-X. As amostras também foram submetidas a análises metalográficas. Conclui-se que as tensões residuais na superfície externa dos tubos são de caráter compressivo. O nível de tensões residuais nos tubos cai com o aumento da energia de soldagem e é menor para tubos soldados utilizando pulsação do que com os soldados sem pulsação e, para esse trabalho, não foi influenciado substancialmente pelo número de passes. As amostras analisadas apresentaram microestruturas convencionais para o aço empregado.This work aims in evaluate the effect of orbital TIG welding on the joint's residual stress level, the final microstructure and the superficial aspect of the weld filet, observing the welding energy, number of passes and the type of pulsation effects in small diameter pipes. The test specimens were welded with different energy, pulsation and number of passes levels and after that it were submitted to residual stress measurement in a X-Ray diffractometer, samples were extracted from the test specimens and it were submitted to metallographic analysis. The ending of this work is that: residual stress in the pipes outer surface are compressive, residual stress level in pipes goes down with increasing welding energy, it is smaller for pipes welded with pulsation and in this work it were not effectively influenced by number of passes

  14. Manômetros artesanais não medem com precisão a pressão de balão dos tubos endotraqueais

    Directory of Open Access Journals (Sweden)

    Raquel Annoni

    2015-09-01

    Full Text Available RESUMOObjetivo:Testar a concordância entre dispositivos artesanais e um manômetro especificamente projetado para esse fim.Métodos:Testamos em 79 sujeitos a concordância entre as mensurações realizadas com 2 dispositivos artesanalmente adaptados para medir a pressão de balão dos tubos endotraqueais e as obtidas com uso de um manômetro específico para esse fim. A pressão de balão foi medida com um manômetro comercial e com dois dispositivos artesanais montados a partir de esfigmomanômetro aneroides. Os dados foram comparados utilizando os testes de Wilcoxon e Spearman, o coeficiente de correlação intraclasse e a análise do limite de concordância.Resultados:As pressões do balão medidas com os dispositivos artesanais foram significantemente diferentes das medidas obtidas com o dispositivo comercial (as pressões foram mais elevadas nas mensurações obtidas com o dispositivo artesanal 1 e mais baixas nas avaliações realizadas com o dispositivo artesanal 2. O coeficiente de correlação intraclasse entre o dispositivo comercial e os dispositivos 1 e 2 foi excelente (0,8; p < 0,001 e bom (0,66; p < 0,001, respectivamente. No entanto, os gráficos de Bland-Altman demonstraram limites amplos de concordância entre os dispositivos 1 e 2 e o dispositivo comercial.Conclusão:Os manômetros artesanais não proporcionam mensurações precisas da pressão do balão, quando comparados a um dispositivo específico para esse fim e, portanto, não devem ser utilizados na avaliação de pacientes mecanicamente ventilados em substituição aos manômetros comerciais específicos para avaliação da pressão do balão.

  15. Impacto ecológico de los Intercambiadores de calor de tubo y coraza; Ecological impact of Shell and tube heat exchangers

    Directory of Open Access Journals (Sweden)

    Maida Bárbara Reyes Rodríguez

    2015-04-01

    Full Text Available Los intercambiadores de calor de tubo y coraza son de los equipos más importantes en la industria. Su diseño termodinámico se basa en el coeficiente global de transferencia de calor y la caída de presión total. En 2007 se estableció una nueva propiedad termodinámica denominada “Entransía”, que expresa la capacidad de un cuerpo de transferir calor. A la pérdida de esa capacidad se le denomina “Disipación de Entransía”. Para evaluar el impacto ecológico de las máquinas térmicas, Angulo-Brown creó en 1991 la llamada función ecológica. En el presente trabajo se combinó la disipación de entransía con la función ecológica y se creó una nueva expresión para evaluar el impacto ambiental de los intercambiadores de calor. Se realizó además la optimización muti-objetivo de estos equipos. Fueron utilizadas como funciones objetivo la función ecológica y el costo. Para realizar la optimización se utilizó el método de los Algoritmos Genéticos.Shell and tube heat exchangers are ones the most important equipment in the industry. Their thermodynamic design is based on the global heat transference coefficient and the pressure drop. In 2007 was settled a new thermodynamic property denominated “Entransy”, which expresses the capacity of a body to transfer heat. The loss of this capacity is denominated “Entransy Dissipation”. For evaluating the ecological impact of thermal machines, Angulo-Brown created in 1991 the “ecological function”. In this paper the“entransy dissipation” and the ecological function were combined and a new expression for evaluating the ecological impact of shell and tube heat exchangers was created. A multi-objective optimization of this equipment wasalso realized. The ecological function and the cost wereused as objective functions. For carry out the optimization the method of the Genetic Algorithms was used.

  16. Estudo in vitro da resistência ao cisalhamento da colagem direta de tubos ortodônticos em molares In vitro study of shear bond strength in direct bonding of orthodontic molar tubes

    Directory of Open Access Journals (Sweden)

    Célia Regina Maio Pinzan Vercelino

    2011-06-01

    Full Text Available INTRODUÇÃO: apesar da colagem direta despender menor tempo clínico, com maior preservação da integridade gengival, ainda hoje se observa uma alta incidência de bandagem dos molares. Portanto, torna-se interessante a idealização de recursos para o aumento da eficiência desse procedimento para dentes submetidos a maiores impactos mastigatórios, como, por exemplo, os molares. OBJETIVO: esse estudo teve o propósito de avaliar se a resistência à adesão com a aplicação de uma camada de resina adicional na região oclusal da interface tubo/dente aumenta a qualidade do procedimento de colagem direta de tubos em molares. MÉTODOS: selecionou-se uma amostra composta por 40 terceiros molares inferiores, que foram aleatoriamente divididos em 2 grupos: Grupo 1 - colagem direta convencional, seguida pela aplicação de uma camada de resina na oclusal da interface tubo/dente; e Grupo 2 - colagem direta convencional. O teste de resistência ao cisalhamento foi realizado 24 horas após a colagem, utilizando-se uma máquina de ensaio universal, operando a uma velocidade de 0,5mm/min. Os resultados foram analisados por meio do teste t independente. RESULTADOS: os valores médios obtidos nos testes de cisalhamento foram: 17,08MPa para o Grupo 1 e 12,60MPa para o Grupo 2. O Grupo 1 apresentou uma resistência ao cisalhamento estatisticamente significativa mais alta do que o Grupo 2. CONCLUSÃO: a aplicação de uma camada adicional de resina na oclusal da interface tubo/dente aumenta a qualidade da adesão do procedimento de colagem direta de tubos ortodônticos em molares.OBJECTIVE: Although direct bonding takes up less clinical time and ensures increased preservation of gingival health, the banding of molar teeth is still widespread nowadays. It would therefore be convenient to devise methods capable of increasing the efficiency of this procedure, notably for teeth subjected to substantial masticatory impact, such as molars. This study was

  17. The use of radioactive inserts in the study of metal deformation during tube-making processes; Emploi de fils metalliques radioactifs pour l'etude des deformations des metaux pendant la fabrication de tubes; Ispol'zovanie radioaktivnykh vtulok dlya izucheniya deformatsii metallov pri protsesse izgotovleniya trub; Empleo de insertos radiactivos en el estudio de la deformacion de los metales durante la fabricacion de tubos

    Energy Technology Data Exchange (ETDEWEB)

    Davison, W H.T. [Tube Investments Research Laboratories, Cambridge (United Kingdom)

    1962-01-15

    foree; les courbes isoactives montrent les deformations du fil radioactif dans la direction normale a la surface du tube. Un examen analogue d'une section perpendiculaire a l'axe du tube dorme un deuxieme diagramme; en combinant les deux diagrammes, on obtient une representation a trois dimensions. Les auteurs du memoire mentionnent quelques resultats obtenus, mais ile s'attachent surtout a exposer la technique experimentale qui trouve une application tres etendue dans l'etude de la deformation des metaux. Le fil metallique radioactif doit etre localise a un millimetre pres, ce qui exige un pouvoir de resolution superieur a celui qui est normalement necessaire pour les explorations medicales au moyen de radioisotopes. Les auteurs analysent l'influence de l'energie y, de la construction du collimateur et de la discrimination energetique sur les problemes a resoudre pour obtenir ce pouvoir de resolution. (author) [Spanish] La memoria informa sobre el empleo de insertos radiactivos en la investigacion de las deformaciones del acero durante la fabricacion de tubos por punzonado rotatorio en caliente. Se irradian en el reactor alambres de hierro o de acero y se insertan en orificios tubulares taladrados en tochos de los mismos materiales, que luego son tratados con arreglo a metodos normales de produccion. Un monitoraje meticuloso demuestra que se pueden despreciar el grado de exposicion a las radiaciones y la contaminacion de la planta. Una vez frios, se exploran los tochos en el laboratorio, utilizando un contador de centelleo con colimador, montado perpendicularmente a la superficie del tocho perforado. Las curvas isodosicas indican la configuracion del inserto deformado en un plano perpendicular a la superficie del tubo. Una exploracion similar de un corte perpendicular al eje del tubo da un segundo diagrama; combinando los dos diagramas se obtiene una representacion tridimensional. Se indican algunos resultados, pero la memoria trata principalmente de la tecnica

  18. Optimization of artificial neural networks for the reconstruction of the neutrons spectrum and their equivalent doses; Optimizacion de redes neuronales artificiales para la reconstruccion del espectro de neutrones y sus dosis equivalentes

    Energy Technology Data Exchange (ETDEWEB)

    Reyes A, A.; Ortiz R, J. M.; Reyes H, A.; Castaneda M, R.; Solis S, L. O.; Vega C, H. R., E-mail: art8291@hotmail.com [Universidad Autonoma de Zacatecas, Unidad Academica de Ingenieria Electrica, Av. Lopez Velarde No. 801, Col. Centro, 98000 Zacatecas (Mexico)

    2014-08-15

    In this work was used the robust design methodology of artificial neural networks to determine a good topology of net able to solve with efficiency the problems of neutrons spectrometry and dosimetry. For the design of the topology of optimized net 36 different net architectures based on an orthogonal arrangement with a configuration L{sub 9}(3{sup 4}), L{sub 4}(3{sup 2}) were trained. For the training of the neural networks, was used a computer code developed in the ambient of Mat lab programming, which automates the process and analysis of the information, reducing the time used in this activity considerably for the investigator. For the training of the propagation nets forward was utilized a neutrons spectrum compendium published by the International Atomic Energy Agency, where of the total 80% was used for the training and 20% for the test, it trained with an inverse propagation algorithm being the entrance data the count rates corresponding to the 7 spheres of the spectrometric system of Bonner spheres, as exit data, the neural network obtains the neutrons spectrum expressed in 60 energy groups and are calculated of simultaneous way 15 dosimetric quantities. (Author)

  19. Reconstruction of neutron spectra using neural networks starting from the Bonner spheres spectrometric system; Reconstruccion de espectros de neutrones usando redes neuronales a partir del sistema espectrometrico de esferas de Bonner

    Energy Technology Data Exchange (ETDEWEB)

    Ortiz R, J.M.; Martinez B, M.R.; Arteaga A, T.; Vega C, H.R.; Hernandez D, V.M.; Manzanares A, E. [Universidad Autonoma de Zacatecas, A.P. 336, 98000 Zacatecas (Mexico)

    2005-07-01

    The artificial neural networks (RN) have been used successfully to solve a wide variety of problems. However to determine an appropriate set of values of the structural parameters and of learning of these, it continues being even a difficult task. Contrary to previous works, here a set of neural networks is designed to reconstruct neutron spectra starting from the counting rates coming from the detectors of the Bonner spheres system, using a systematic and experimental strategy for the robust design of multilayer neural networks of the feed forward type of inverse propagation. The robust design is formulated as a design problem of Taguchi parameters. It was selected a set of 53 neutron spectra, compiled by the International Atomic Energy Agency, the counting rates were calculated that would take place in a Bonner spheres system, the set was arranged according to the wave form of those spectra. With these data and applying the Taguchi methodology to determine the best parameters of the network topology, it was trained and it proved the same one with the spectra. (Author)

  1. Morphological neural networks

    Energy Technology Data Exchange (ETDEWEB)

    Ritter, G.X.; Sussner, P. [Univ. of Florida, Gainesville, FL (United States)

    1996-12-31

    The theory of artificial neural networks has been successfully applied to a wide variety of pattern recognition problems. In this theory, the first step in computing the next state of a neuron or in performing the next layer neural network computation involves the linear operation of multiplying neural values by their synaptic strengths and adding the results. Thresholding usually follows the linear operation in order to provide for nonlinearity of the network. In this paper we introduce a novel class of neural networks, called morphological neural networks, in which the operations of multiplication and addition are replaced by addition and maximum (or minimum), respectively. By taking the maximum (or minimum) of sums instead of the sum of products, morphological network computation is nonlinear before thresholding. As a consequence, the properties of morphological neural networks are drastically different than those of traditional neural network models. In this paper we consider some of these differences and provide some particular examples of morphological neural network.

  2. Neural Tube Defects

    Science.gov (United States)

    Neural tube defects are birth defects of the brain, spine, or spinal cord. They happen in the ... that she is pregnant. The two most common neural tube defects are spina bifida and anencephaly. In ...

  3. Neural tissue-spheres

    DEFF Research Database (Denmark)

    Andersen, Rikke K; Johansen, Mathias; Blaabjerg, Morten

    2007-01-01

    By combining new and established protocols we have developed a procedure for isolation and propagation of neural precursor cells from the forebrain subventricular zone (SVZ) of newborn rats. Small tissue blocks of the SVZ were dissected and propagated en bloc as free-floating neural tissue...... content, thus allowing experimental studies of neural precursor cells and their niche...

  4. Pseudo-aneurisma em tubo valvulado de pericárdio bovino corrugado após reconstrução da aorta ascendente: relato de caso False aneurysm of crimped bovine pericardial conduit after reconstruction of the ascending aorta: case report

    Directory of Open Access Journals (Sweden)

    Noedir A. G. STOLF

    1999-10-01

    Full Text Available Os autores descrevem o caso de paciente que, 9 anos após a correção cirúrgica de um aneurisma de aorta ascendente com tubo valvulado de pericárdio bovino corrugado, evoluiu com a formação de um pseudo-aneurisma de aorta localizado, posteriormente, sobre a linha de sutura do tubo de pericárdio bovino. Foi realizada substituição do tubo de pericárdio bovino por tubo de Dacron valvulado (com prótese mecânica e reimplante dos óstios coronários utilizando-se a técnica de hemi-Cabrol. O tempo de seguimento pós-operatório do paciente é de 12 meses, permanecendo assintomático.The authors describe the case of a patient who had an aneurysm of the ascending aorta repaired with biologic valved crimped bovine pericardial conduit. Nine years after the surgery he presented a false aneurysm of the ascending aorta, located posteriorly on the suture line of the pericardial tube. The patient was reoperated and the pericardial tube was replaced by a valved Dacron composite graft using the hemi- Cabrol technique for the reimplantation of the coronary ostia. At 12 months follow-up the patient remains free of symptoms.

  5. Neural electrical activity and neural network growth.

    Science.gov (United States)

    Gafarov, F M

    2018-05-01

    The development of central and peripheral neural system depends in part on the emergence of the correct functional connectivity in its input and output pathways. Now it is generally accepted that molecular factors guide neurons to establish a primary scaffold that undergoes activity-dependent refinement for building a fully functional circuit. However, a number of experimental results obtained recently shows that the neuronal electrical activity plays an important role in the establishing of initial interneuronal connections. Nevertheless, these processes are rather difficult to study experimentally, due to the absence of theoretical description and quantitative parameters for estimation of the neuronal activity influence on growth in neural networks. In this work we propose a general framework for a theoretical description of the activity-dependent neural network growth. The theoretical description incorporates a closed-loop growth model in which the neural activity can affect neurite outgrowth, which in turn can affect neural activity. We carried out the detailed quantitative analysis of spatiotemporal activity patterns and studied the relationship between individual cells and the network as a whole to explore the relationship between developing connectivity and activity patterns. The model, developed in this work will allow us to develop new experimental techniques for studying and quantifying the influence of the neuronal activity on growth processes in neural networks and may lead to a novel techniques for constructing large-scale neural networks by self-organization. Copyright © 2018 Elsevier Ltd. All rights reserved.

  6. Atividade antibacteriana de tubos endotraqueais revestidos com dióxido de titânio padrão e dopados com nitrogênio: um estudo in vitro

    Directory of Open Access Journals (Sweden)

    Valentina Caratto

    Full Text Available RESUMO Objetivo: Avaliar a atividade antibacteriana contra Staphylococcus aureus e Pseudomonas aeruginosa de dois revestimentos endotraqueais com nanopartículas e fotocatálise sob luz visível. Métodos: Testaram-se dois tipos de nanopartículas de titânio: anatase padrão (TiO2 e TiO2 nano-dopada (N-TiO2. As nanopartículas foram colocadas em superfície interna de segmentos de tubos endotraqueais comerciais, aplicadas sobre um filtro de acetato de celulose; os tubos endotraqueais controle foram deixados sem revestimento de nanopartículas. Em cada tubo endotraqueal foi inoculado um total de 150 unidades formadoras de colônia e, a seguir, estes foram expostos a uma fonte de luz fluorescente (3700 lux, comprimento de onda de 300 - 700nm por 5, 10, 20, 40, 60 e 80 minutos. Contaram-se as Unidades Formadoras de Colônia após 24 horas de incubação a 37ºC. A inativação bacteriana foi calculada como a redução porcentual do crescimento bacteriano em comparação a tubos não expostos à luz. Resultados: Na ausência de luz, não se observou qualquer atividade antibacteriana relevante contra qualquer das cepas estudadas. Para P. aeruginosa, ambos os revestimentos tiveram inativação bacteriana mais elevada do que o controle em qualquer dos momentos de avaliação (p < 0,001, sendo que não se observaram diferenças entre o revestimento padrão e nano-dopado. Para S. aureus, a inativação foi maior que os controles, começando a partir de 5 minutos para nano-dopado (p = 0,018 e 10 minutos para o revestimento padrão (p = 0,014; a inativação com a forma nano-dopada foi maior do que com a forma padrão aos 20 minutos (p < 0,001, 40 minutos (p < 0,001 e 60 minutos (p < 0,001. Conclusões: O revestimento com nanopartículas de titânio comercial padrão e nano-dopado inibiu o crescimento bacteriano sob a luz fluorescente visível. o revestimento nano-dopado teve maior atividade antibacteriana contra S. aureus em comparação à atividade

  7. Chaotic diagonal recurrent neural network

    International Nuclear Information System (INIS)

    Wang Xing-Yuan; Zhang Yi

    2012-01-01

    We propose a novel neural network based on a diagonal recurrent neural network and chaos, and its structure and learning algorithm are designed. The multilayer feedforward neural network, diagonal recurrent neural network, and chaotic diagonal recurrent neural network are used to approach the cubic symmetry map. The simulation results show that the approximation capability of the chaotic diagonal recurrent neural network is better than the other two neural networks. (interdisciplinary physics and related areas of science and technology)

  8. Potencial del Agua del suelo

    Directory of Open Access Journals (Sweden)

    Bustamante Heliodoro

    1986-12-01

    Full Text Available La energía potencial del agua presenta diferencias de un punto del suelo a otro; esas diferencias son las que originan el movimiento del agua de acuerdo a la tendencia universal de la materia en el sentido de moverse de donde la energía potencial es mayor a donde dicha energía es menor. En el suelo el agua en consecuencia se mueve hacia donde su energía decrece hasta lograr su estado de equilibrio. Se desprende entonces que la cantidad de energía potencial absoluta contenida en el agua, no es importante por sí misma, sino por su relación con la energía en diferentes lugares dentro del suelo. El concepto Potencial de agua del suelo es un criterio para esta energía.

  9. Performance optimization methodology in a Francis turbine vacuum cleaner based on the modification of the boundary conditions; Metodologia de optimizacion del rendimiento en un aspirador de turbina Francis en base a la modificacion de las condiciones de frontera

    Energy Technology Data Exchange (ETDEWEB)

    Galvan Gonzalez, S.; Rubio Maya, C.; Mendoza Covarrubias, C. [Universidad Michoacana de San Nicolas Hidalgo, Morelia, Michoacan (Mexico)]. E-mail: srgalvan@umich.mx; crmaya@umich.mx; cmendoza@umich.mx; Pacheco Ibarra, J.; Martinez Patino, J. [Universidad de Guanajuato, Salamanca, Guanajuato (Mexico)

    2010-11-15

    This paper focus on establishing an optimization methodology for maximizing the draft tube performance as a function of the inlet velocity profile. The overall work is defined by four steps: the inlet velocity profile parametrization, the numerical optimization set-up, the numerical computational fluid dynamics (CFD) draft tube model and the objective function definition. However as the inlet velocity profile is a new challenge, each step of the parametrization must be properly validated. In the first step, a suitable parametrization with an appropriate number of variables is chosen to approximate an experimental draft tube inlet velocity profile. The second step considers the reduction of the actual numerical model to develop the CFD calculations. In the third step, the optimization algorithm set-up is specified. Finally, the objective function is evaluated. As each step is properly validated, it is considered this proved methodology will help to find an inlet velocity profile shape which will be able to suppress or mitigate the undesirable draft tube flow characteristics. [Spanish] Este documento se enfoca en establecer una metodologia de optimizacion para maximizar el rendimiento del tubo de aspiracion en funcion de las condiciones de frontera del aspirador. El metodo es definido en cuatro etapas: la parametrizacion del perfil de velocidades, la evaluacion del algoritmo de optimizacion, la valoracion de la funcion objetivo y la validacion del modelo numerico. La parametrizacion se realiza con un numero de variables apropiado para aproximar el perfil de velocidades experimental. El segundo paso considera establecer los parametros del algoritmo de optimizacion, la funcion objetivo es obtenida mediante un estudio de sensibilidad y el modelo numerico es validado y reducido en la cantidad de elementos para adecuarlo al proceso de optimizacion. Se considera que esta metodologia ayudara a encontrar un perfil de velocidad de entrada el cual reduzca las perdidas de

  10. Evolvable Neural Software System

    Science.gov (United States)

    Curtis, Steven A.

    2009-01-01

    The Evolvable Neural Software System (ENSS) is composed of sets of Neural Basis Functions (NBFs), which can be totally autonomously created and removed according to the changing needs and requirements of the software system. The resulting structure is both hierarchical and self-similar in that a given set of NBFs may have a ruler NBF, which in turn communicates with other sets of NBFs. These sets of NBFs may function as nodes to a ruler node, which are also NBF constructs. In this manner, the synthetic neural system can exhibit the complexity, three-dimensional connectivity, and adaptability of biological neural systems. An added advantage of ENSS over a natural neural system is its ability to modify its core genetic code in response to environmental changes as reflected in needs and requirements. The neural system is fully adaptive and evolvable and is trainable before release. It continues to rewire itself while on the job. The NBF is a unique, bilevel intelligence neural system composed of a higher-level heuristic neural system (HNS) and a lower-level, autonomic neural system (ANS). Taken together, the HNS and the ANS give each NBF the complete capabilities of a biological neural system to match sensory inputs to actions. Another feature of the NBF is the Evolvable Neural Interface (ENI), which links the HNS and ANS. The ENI solves the interface problem between these two systems by actively adapting and evolving from a primitive initial state (a Neural Thread) to a complicated, operational ENI and successfully adapting to a training sequence of sensory input. This simulates the adaptation of a biological neural system in a developmental phase. Within the greater multi-NBF and multi-node ENSS, self-similar ENI s provide the basis for inter-NBF and inter-node connectivity.

  11. Analysis of the uranium price predicted to 24 months, implementing neural networks and the Monte Carlo method like predictive tools; Analisis del precio del uranio pronosticado a 24 meses, implementando redes neuronales y el metodo de Monte Carlo como herramientas predictivas

    Energy Technology Data Exchange (ETDEWEB)

    Esquivel E, J.; Ramirez S, J. R.; Palacios H, J. C., E-mail: jaime.esquivel@fi.uaemex.mx [ININ, Carretera Mexico-Toluca s/n, 52750 Ocoyoacac, Estado de Mexico (Mexico)

    2011-11-15

    The present work shows predicted prices of the uranium, using a neural network. The importance of predicting financial indexes of an energy resource, in this case, allows establishing budgetary measures, as well as the costs of the resource to medium period. The uranium is part of the main energy generating fuels and as such, its price rebounds in the financial analyses, due to this is appealed to predictive methods to obtain an outline referent to the financial behaviour that will have in a certain time. In this study, two methodologies are used for the prediction of the uranium price: the Monte Carlo method and the neural networks. These methods allow predicting the indexes of monthly costs, for a two years period, starting from the second bimonthly of 2011. For the prediction the uranium costs are used, registered from the year 2005. (Author)

  12. A neural flow estimator

    DEFF Research Database (Denmark)

    Jørgensen, Ivan Harald Holger; Bogason, Gudmundur; Bruun, Erik

    1995-01-01

    This paper proposes a new way to estimate the flow in a micromechanical flow channel. A neural network is used to estimate the delay of random temperature fluctuations induced in a fluid. The design and implementation of a hardware efficient neural flow estimator is described. The system...... is implemented using switched-current technique and is capable of estimating flow in the μl/s range. The neural estimator is built around a multiplierless neural network, containing 96 synaptic weights which are updated using the LMS1-algorithm. An experimental chip has been designed that operates at 5 V...

  13. Neural Systems Laboratory

    Data.gov (United States)

    Federal Laboratory Consortium — As part of the Electrical and Computer Engineering Department and The Institute for System Research, the Neural Systems Laboratory studies the functionality of the...

  14. Neural Networks: Implementations and Applications

    OpenAIRE

    Vonk, E.; Veelenturf, L.P.J.; Jain, L.C.

    1996-01-01

    Artificial neural networks, also called neural networks, have been used successfully in many fields including engineering, science and business. This paper presents the implementation of several neural network simulators and their applications in character recognition and other engineering areas

  15. del alcoholismo

    Directory of Open Access Journals (Sweden)

    Rodrigo Arias Duque

    2005-01-01

    Full Text Available Desde el punto de vista farmacológico, es importante comprender qué es el alcohol y cómo actúa en el organismo. No existe una causa simple, sino una interacción complicada de factores neuroquímicos, fisiológicos, psicológicos y sociales que originan y desarrollan esta grave enfermedad fármaco-dependiente. La acción psicofisiológica y farmacodinámica del alcohol es fundamentalmente depresiva, por la reducción de la transmisión sináptica en el sistema nervioso humano. Es un hecho conocido que el consumo excesivo de alcohol causa una disfunción aguda y crónica del cerebro, produciendo trastornos en el sistema nervioso central, presentando alteraciones en la memoria y en las funciones intelectuales como cálculo, comprensión y aprendizaje. A nivel hepático tiene lugar, en su mayoría, el metabolismo del alcohol, produciéndose un hígado graso alcohólico, aumentando el tamaño, terminando en necrosis e inflamación grave del hígado; esto se llama hepatitis alcohólica, y si se sigue consumiendo alcohol se desarrollará la cirrosis. El alcohol también ha estado relacionado con alteraciones del miocardio; se ha constatado en animales de experimentación sanos que tanto la velocidad de contracción del músculo cardiaco y su máxima tensión disminuyen en presencia del alcohol, como consecuencia, la fuerza de cada contracción y el aumento de presión en el ventrículo izquierdo son menores, perdiendo eficacia el corazón como bomba.

  16. Artificial neural network based model to calculate the environmental variables of the tobacco drying process; Modelo basado en redes neuronales artificiales para el cálculo de parámetros ambientales en el proceso de curado del tabaco

    Directory of Open Access Journals (Sweden)

    Víctor Martínez-Martínez

    2013-06-01

    Full Text Available This paper presents an Artificial Neural Network (ANN based model for environmental variables related to the tobacco drying process. A fitting ANN was used to estimate and predict temperature and relative humidity inside the tobacco dryer: the estimation consists of calculating the value of these variables in different locations of the dryer and the prediction consists of forecasting the value of these variables with different time horizons. The proposed model has been validated with temperature and relative humidity data obtained from a real tobacco dryer using a Wireless Sensor Network (WSN. On the one hand, an error under 2% was achieved, obtaining temperature as a function of temperature and relative humidity in other locations in the estimation task. Besides, an error around 1.5 times lower than the one obtained with an interpolation method was achieved in the prediction task when the temperature inside the tobacco mass was predicted with time horizons over 2.5 hours as a function of its present and past values. These results show that ANN-based models can be used to improve the tobacco drying process because with these types of models the value of environmental variables can be predicted in the near future and can be estimated in other locations with low errors.

  17. Prediction of the daily share price fluctuations of SURAMINV. A neural netword model Predicción del comportamiento diario de la acción de SURAMINV. Un modelo de redes neuronales

    Directory of Open Access Journals (Sweden)

    Jaime Enrique Arrieta Bechara

    2009-12-01

    Full Text Available As opposed to the weak form of efficient-market hypothesis, the current study shows that it is possible to do good predictions about the daily share price fluctuations of Suraminv, using artificial neural network models. Furthermore, the forecasts obtained are used to analyze the possibility of gaining extraordinary returns with regard to the Buy & Hold strategy, through negotiation systems with basic rules.La investigación muestra que es posible realizar, por medio de modelos de redes neuronales artificiales, buenas predicciones sobre el comportamiento diario de la acción de SURAMINV. Tales resultados contrarían la hipótesis de la teoría de eficiencia débil de mercado. A partir de dichas predicciones y con el uso de sistemas de negociación, se evalúa la posibilidad de obtener rendimientos extraordinarios sobre la estrategia Buy & Hold teniendo en cuenta costos de transacción y oportunidad.

  18. Reconstruction of the neutron spectrum using an artificial neural network in CPU and GPU; Reconstruccion del espectro de neutrones usando una red neuronal artificial (RNA) en CPU y GPU

    Energy Technology Data Exchange (ETDEWEB)

    Hernandez D, V. M.; Moreno M, A.; Ortiz L, M. A. [Universidad de Cordoba, 14002 Cordoba (Spain); Vega C, H. R.; Alonso M, O. E., E-mail: vic.mc68010@gmail.com [Universidad Autonoma de Zacatecas, 98000 Zacatecas, Zac. (Mexico)

    2016-10-15

    The increase in computing power in personal computers has been increasing, computers now have several processors in the CPU and in addition multiple CUDA cores in the graphics processing unit (GPU); both systems can be used individually or combined to perform scientific computation without resorting to processor or supercomputing arrangements. The Bonner sphere spectrometer is the most commonly used multi-element system for neutron detection purposes and its associated spectrum. Each sphere-detector combination gives a particular response that depends on the energy of the neutrons, and the total set of these responses is known like the responses matrix Rφ(E). Thus, the counting rates obtained with each sphere and the neutron spectrum is related to the Fredholm equation in its discrete version. For the reconstruction of the spectrum has a system of poorly conditioned equations with an infinite number of solutions and to find the appropriate solution, it has been proposed the use of artificial intelligence through neural networks with different platforms CPU and GPU. (Author)

  19. Critical Branching Neural Networks

    Science.gov (United States)

    Kello, Christopher T.

    2013-01-01

    It is now well-established that intrinsic variations in human neural and behavioral activity tend to exhibit scaling laws in their fluctuations and distributions. The meaning of these scaling laws is an ongoing matter of debate between isolable causes versus pervasive causes. A spiking neural network model is presented that self-tunes to critical…

  20. Consciousness and neural plasticity

    DEFF Research Database (Denmark)

    changes or to abandon the strong identity thesis altogether. Were one to pursue a theory according to which consciousness is not an epiphenomenon to brain processes, consciousness may in fact affect its own neural basis. The neural correlate of consciousness is often seen as a stable structure, that is...

  1. Viabilidade do pólen e desenvolvimento do tubo polínico em macieira (Malus spp. Germination of pollen and the development of pollen tubes in apple (Malus spp.

    Directory of Open Access Journals (Sweden)

    Adriana Cibele de Mesquita Dantas

    2005-12-01

    Full Text Available No presente trabalho, estudaram-se características associadas à germinação in vitro e ao desenvolvimento in vivo do tubo polínico em seis variedades-copa e de porta-enxertos de macieira como subsídios para o estabelecimento de programas de melhoramento genético. Utilizou-se de pólen de seis cultivares de macieira inoculado em meio de cultura com ágar (10 g.L-1 em água destilada, combinados com concentrações de sacarose (0; 10; 20; 30; 40 e 50% e ácido bórico (0 e 40 mg.L-1. Para o estudo do desenvolvimento do tubo polínico, realizou-se coleta das flores em quatro períodos (6; 12; 24 e 48 horas após as polinizações em M9 x Marubakaido e a autofecundação em M9, sendo os tubos polínicos analisados em coloração de azul de anilina acidificada/carmim acético e em fluorescência. A sacarose, em concentrações entre 15% a 25%, pode ser empregada com sucesso para a germinação in vitro de grãos de pólen da macieira. O ácido bórico não teve efeito positivo para esta característica. Na ausência do ácido bórico e na presença de 15% de sacarose, observaram-se os maiores percentuais de germinação: Fuji (51,1%, Imperatriz (31,7%, M.9 (20,8%, Catarina (19,2%, Gala (13,7% e Marubakaido (6,1%. Quanto ao desenvolvimento do tubo polínico, com 12 horas da polinização, iniciou-se a germinação no pólen, no estigma, no cruzamento M.9 x Marubakaido, e após 24 horas da polinização observou-se 83% de germinação. As técnicas de coloração com azul de anilina acidificada com carmim acético e de visualização em fluorescência foram eficientes na visualização e coloração dos grãos de pólen e do desenvolvimento dos tubos polínicos.In the present work it was studied features associated to the germination of pollen and the development of pollen tubes in six apple varieties as subsidies for the establishment of genetic improvement programs. Pollen grains were inoculated in culture medium with distilled water, agar (10

  2. EVALUACIÓN DEL POLICULTIVO DE BOCACHICO Prochilodus magdalenae Y TILAPA Oreochromis niloticus UTILIZANDO SUPERFICIES FIJADORAS DE PERIFITON

    Directory of Open Access Journals (Sweden)

    J. J. García

    2011-01-01

    Full Text Available La piscicultura es una actividad importante para satisfacer la demanda alimenticia de una población en crecimiento y en su práctica es necesario desarrollar tecnologías responsables con el ambiente. El policultivo de tilapia-bocachico es relevante por la importancia de estas especies a nivel nacional; tilapia por sus características zootécnicas, y bocachico por su hábito alimentario detritívoro-iliófago, recientemente visto como un pez ecológico. El cultivo basado en perifiton permitiría un sistema altamente eficiente y más limpio, pues aporta alimento natural a los peces y mejora la calidad del agua. Para evaluar el efecto del perifiton sobre el desempeño del policultivo tilapia-bocachico, se ejecutó un experimento durante ocho meses en 18 estanques de 90 m2, con 2,6 tilapias/ m2 y 0,7 bocachicos/m2, sin fertilización; como sustrato para perifiton se instalaron de forma vertical tubos plásticos (3,3 tubos/m2, que se constituyeron en una variable por evaluar. Adicionalmente, tres estrategias alimentarias fueron evaluadas: 0 (sin alimento, alimentación con ración del 20% de proteína bruta (PB y alimentación con ración del 25% de PB. Se utilizó un diseño factorial 2x3 en bloques completos al azar con tres repeticiones por tratamiento y se analizaron datos productivos mediante ANOVA con un modelo lineal general (P < 0,05. No fueron encontrados efectos del sustrato sobre los parámetros estudiados. Hubo efectos simples de la estrategia alimentaria sobre el desempeño de los peces. Por lo pronto, puede ser concluido que la producción basada en perifiton no genera problemas en el sistema ni en los peces y que se requiere más investigación para consolidar la tecnología.

  3. Transferência de oxigênio em reatores de leito fluidizado com circulação em tubos concêntricos em meios bifásico e trifásico com variação da relação entre diâmetros

    OpenAIRE

    Araújo,Leandro Santos de; Dall'Aglio Sobrinho,Milton; Gebara,Dib

    2010-01-01

    A eficiência do reator de leito fluidizado com circulação em tubos concêntricos depende das condições hidrodinâmicas que influem na transferência de oxigênio ao biofilme. Este trabalho investigou a influência da relação entre diâmetros dos tubos e da concentração de meio suporte (areia), sobre o coeficiente global de transferência de oxigênio (K La). Os ensaios - em reatores de 2,6 m de altura, com diâmetro externo de 250 mm e internos de 100, 125, 150 e 200 mm - empregaram vazões de ar até 2...

  4. Culturas del Mundo

    DEFF Research Database (Denmark)

    Benwell, Ann Fenger; Costa, Alberto; Waehle, Espen

    2006-01-01

    ’Culturas del mundo. Colecciones del Museo Nacional de Dinamarca’ with Ann Fenger Benwell in Culturas del Mundo. Colecciones del Museo Nacional de Dinamarca, ed. Silvia Sauquet, Fundación "la Caixa", Barcelona 2006, pp. 31-39......’Culturas del mundo. Colecciones del Museo Nacional de Dinamarca’ with Ann Fenger Benwell in Culturas del Mundo. Colecciones del Museo Nacional de Dinamarca, ed. Silvia Sauquet, Fundación "la Caixa", Barcelona 2006, pp. 31-39...

  5. Dynamics of neural cryptography.

    Science.gov (United States)

    Ruttor, Andreas; Kinzel, Wolfgang; Kanter, Ido

    2007-05-01

    Synchronization of neural networks has been used for public channel protocols in cryptography. In the case of tree parity machines the dynamics of both bidirectional synchronization and unidirectional learning is driven by attractive and repulsive stochastic forces. Thus it can be described well by a random walk model for the overlap between participating neural networks. For that purpose transition probabilities and scaling laws for the step sizes are derived analytically. Both these calculations as well as numerical simulations show that bidirectional interaction leads to full synchronization on average. In contrast, successful learning is only possible by means of fluctuations. Consequently, synchronization is much faster than learning, which is essential for the security of the neural key-exchange protocol. However, this qualitative difference between bidirectional and unidirectional interaction vanishes if tree parity machines with more than three hidden units are used, so that those neural networks are not suitable for neural cryptography. In addition, the effective number of keys which can be generated by the neural key-exchange protocol is calculated using the entropy of the weight distribution. As this quantity increases exponentially with the system size, brute-force attacks on neural cryptography can easily be made unfeasible.

  6. Dynamics of neural cryptography

    International Nuclear Information System (INIS)

    Ruttor, Andreas; Kinzel, Wolfgang; Kanter, Ido

    2007-01-01

    Synchronization of neural networks has been used for public channel protocols in cryptography. In the case of tree parity machines the dynamics of both bidirectional synchronization and unidirectional learning is driven by attractive and repulsive stochastic forces. Thus it can be described well by a random walk model for the overlap between participating neural networks. For that purpose transition probabilities and scaling laws for the step sizes are derived analytically. Both these calculations as well as numerical simulations show that bidirectional interaction leads to full synchronization on average. In contrast, successful learning is only possible by means of fluctuations. Consequently, synchronization is much faster than learning, which is essential for the security of the neural key-exchange protocol. However, this qualitative difference between bidirectional and unidirectional interaction vanishes if tree parity machines with more than three hidden units are used, so that those neural networks are not suitable for neural cryptography. In addition, the effective number of keys which can be generated by the neural key-exchange protocol is calculated using the entropy of the weight distribution. As this quantity increases exponentially with the system size, brute-force attacks on neural cryptography can easily be made unfeasible

  7. Dynamics of neural cryptography

    Science.gov (United States)

    Ruttor, Andreas; Kinzel, Wolfgang; Kanter, Ido

    2007-05-01

    Synchronization of neural networks has been used for public channel protocols in cryptography. In the case of tree parity machines the dynamics of both bidirectional synchronization and unidirectional learning is driven by attractive and repulsive stochastic forces. Thus it can be described well by a random walk model for the overlap between participating neural networks. For that purpose transition probabilities and scaling laws for the step sizes are derived analytically. Both these calculations as well as numerical simulations show that bidirectional interaction leads to full synchronization on average. In contrast, successful learning is only possible by means of fluctuations. Consequently, synchronization is much faster than learning, which is essential for the security of the neural key-exchange protocol. However, this qualitative difference between bidirectional and unidirectional interaction vanishes if tree parity machines with more than three hidden units are used, so that those neural networks are not suitable for neural cryptography. In addition, the effective number of keys which can be generated by the neural key-exchange protocol is calculated using the entropy of the weight distribution. As this quantity increases exponentially with the system size, brute-force attacks on neural cryptography can easily be made unfeasible.

  8. Design of an artificial neural network, with the topology oriented to the reconstruction of neutron spectra; Diseno de una red neuronal artificial, con la topologia orientada a la reconstruccion del espectro de neutrones

    Energy Technology Data Exchange (ETDEWEB)

    Arteaga A, T.; Ortiz R, J.M.; Vega C, H.R.; Hernandez D, V.M.; Manzanares A, E.; Mercado S, G.A. [Unidades Academicas de Estudios Nucleares, Ingenieria Electrica y Matematicas, Universidad de Zacatecas, A.P. 336, 98000 Zacatecas (Mexico)]. e-mail: tarcicio70@yahoo.co.uk

    2006-07-01

    People that live in high places respect to the sea level, in latitudes far from the equator or that they travel by plane, they are exposed to atmospheres of high radiation generated by the cosmic rays. Another atmosphere with radiation is the medical equipment, particle accelerators and nuclear reactors. The evaluation of the biological risk for neutron radiation requires an appropriate and sure dosimetry. A commonly used system is the Bonner Sphere Spectrometer (EEB) with the purpose of reconstructing the spectrum that is important because the equivalent dose for neutrons depends strongly on its energy. The count rates obtained in each sphere are treated, in most of the cases, for iterative methods, Monte Carlo or Maximum Entropy. Each one of them has difficulties that it motivates to the development of complementary procedures. Recently it has been used Artificial Neural Networks, ANN) and not yet conclusive results have been obtained. In this work it was designed an ANN to obtain the neutron energy spectrum neutrons starting from the counting rate of count of an EEB. The ANN was trained with 129 reference spectra obtained of the IAEA (1990, 2001), 24 were built as defined energy, including isotopic sources of neutrons of reference and operational, of accelerators, reactors, mathematical functions, and of defined energy with several peaks. The spectrum was transformed from lethargy units to energy and were reaccommodated in 31 energies using the Monte Carlo code 4C. The reaccommodated spectra and the response matrix UTA4 were used to calculate the prospective count rates in the EEB. These rates were used as entrance and its respective spectrum was used as output during the net training. The net design is Retropropagation type with 5 layers of 7, 140, 140, 140 and 31 neurons, transfer function logsig, tansig, logsig, logsig, logsig respectively. Training algorithm, traingdx. After the training, the net was proven with a group of training spectra and others that

  9. Tubo de PVC liso com diferentes envoltórios como material alternativo na drenagem subterrânea Smooth PVC tube with different envelopes as an alternative material in the subsurface drainage

    Directory of Open Access Journals (Sweden)

    Florício P. de Almeida

    2003-04-01

    Full Text Available Em regiões áridas e semi-áridas irrigadas a drenagem é, freqüentemente, necessária para prevenir o encharcamento do solo e o controle da salinidade. Um dos principais obstáculos na instalação de um sistema de drenagem subterrânea é o alto custo do investimento inicial. Assim, alguma contribuição que reduza o custo da instalação dos drenos e também do material usado, é altamente vantajosa. Diante disso, o objetivo desta pesquisa foi avaliar, em condições de laboratório, o desempenho hidráulico do sistema drenante constituído pelo tubo de PVC liso, próprio para esgoto doméstico, de 50,0 mm de diâmetro nominal e área aberta de 23,0 cm² m-1, e por três tipos de envoltório. O desempenho do tubo drenante de PVC liso demonstrou que esse material é tecnicamente viável para drenagem agrícola, principalmente com o uso de brita como envoltório.In irrigated arid and semi-arid regions the drainage is, frequently, necessary to prevent the waterlogging of the soil and to control the salinity. One of the main obstacles in the installation of a subsurface drainage system is the high cost of the initial investment. Thus, some contribution that reduces the cost of the installation of the drains and also of the material used is highly advantageous. The objective of this research was to evaluate, under laboratory conditions, the hydraulic performance of the drainage system constituted by smooth PVC tube used for sewer with 50.0 mm of nominal diameter and open area of 23.0 cm² m-1 and different types of envelopes, as an alternative material for subsurface drainage. The performance of the smooth PVC tube demonstrated that this material is technically viable for agricultural drainage principally when used with single stones as envelope.

  10. Anatomía floral comparativa del género Polianthes (Agavaceae Comparative floral anatomy of the genus Polianthes (Agavaceae

    Directory of Open Access Journals (Sweden)

    Héctor Serrano-Casas

    2011-03-01

    Full Text Available Se realizó un estudio anatómico de las flores de algunas especies en los subgéneros Polianthes y Bravoa del género Polianthes L. (Agavaceae, con el propósito de investigar si la actual clasificación subgenérica es adecuada. Los taxa analizados del subgénero Polianthes fueron P. densiflora, P. nelsonii y P. platyphylla, y del subgénero Bravoa, P. geminiflora var. geminiflora, P. howardii y P. multicolor. Las características anatómicas florales entre las especies son similares y comparten con otros miembros de la familia Agavaceae los nectarios septales y los óvulos anátropos, bitégmicos y crasinucelados. En los taxa del subgénero Bravoa, los filamentos se originan en la base del tubo floral, mientras que en el subgénero Polianthes se originan por debajo de los tépalos internos del perianto. Anteriormente, sin considerar la anatomía de las flores, se planteaba que los filamentos se originaban en ambos subgéneros desde la base del tubo del perianto y que éstos permanecían adnados al mismo, separándose a diferentes niveles. En el nivel interespecífico, P. howardii presenta nectarios de mayor longitud que los lóculos, en relación con los de las otras especies estudiadas.An anatomical floral study of some species of the genus Polianthes (Agavaceae, of both subgenus Polianthes and subgenus Bravoa (Agavaceae was carried out, with the aim of testing the adequacy of the present subgeneric classification. The taxa studied of subgenus Polianthes were P. densiflora, P. nelsonii and P. platyphylla; and P. geminiflora var. geminiflora, P. howardii and P. multicolor of subgenus Bravoa. The anatomical characters between these species are similar, sharing with other members of the Agavaceae family the septal nectaries and the anatropous, bitegmic, and crassinucellated ovules. In the taxa of subgenus Bravoa, the filaments originate from the floral tube base, while in subgenus Polianthes they originate near the base of the internal tepals

  11. ANT Advanced Neural Tool

    Energy Technology Data Exchange (ETDEWEB)

    Labrador, I.; Carrasco, R.; Martinez, L.

    1996-07-01

    This paper describes a practical introduction to the use of Artificial Neural Networks. Artificial Neural Nets are often used as an alternative to the traditional symbolic manipulation and first order logic used in Artificial Intelligence, due the high degree of difficulty to solve problems that can not be handled by programmers using algorithmic strategies. As a particular case of Neural Net a Multilayer Perception developed by programming in C language on OS9 real time operating system is presented. A detailed description about the program structure and practical use are included. Finally, several application examples that have been treated with the tool are presented, and some suggestions about hardware implementations. (Author) 15 refs.

  12. ANT Advanced Neural Tool

    International Nuclear Information System (INIS)

    Labrador, I.; Carrasco, R.; Martinez, L.

    1996-01-01

    This paper describes a practical introduction to the use of Artificial Neural Networks. Artificial Neural Nets are often used as an alternative to the traditional symbolic manipulation and first order logic used in Artificial Intelligence, due the high degree of difficulty to solve problems that can not be handled by programmers using algorithmic strategies. As a particular case of Neural Net a Multilayer Perception developed by programming in C language on OS9 real time operating system is presented. A detailed description about the program structure and practical use are included. Finally, several application examples that have been treated with the tool are presented, and some suggestions about hardware implementations. (Author) 15 refs

  13. Hidden neural networks

    DEFF Research Database (Denmark)

    Krogh, Anders Stærmose; Riis, Søren Kamaric

    1999-01-01

    A general framework for hybrids of hidden Markov models (HMMs) and neural networks (NNs) called hidden neural networks (HNNs) is described. The article begins by reviewing standard HMMs and estimation by conditional maximum likelihood, which is used by the HNN. In the HNN, the usual HMM probability...... parameters are replaced by the outputs of state-specific neural networks. As opposed to many other hybrids, the HNN is normalized globally and therefore has a valid probabilistic interpretation. All parameters in the HNN are estimated simultaneously according to the discriminative conditional maximum...... likelihood criterion. The HNN can be viewed as an undirected probabilistic independence network (a graphical model), where the neural networks provide a compact representation of the clique functions. An evaluation of the HNN on the task of recognizing broad phoneme classes in the TIMIT database shows clear...

  14. Neural networks for aircraft control

    Science.gov (United States)

    Linse, Dennis

    1990-01-01

    Current research in Artificial Neural Networks indicates that networks offer some potential advantages in adaptation and fault tolerance. This research is directed at determining the possible applicability of neural networks to aircraft control. The first application will be to aircraft trim. Neural network node characteristics, network topology and operation, neural network learning and example histories using neighboring optimal control with a neural net are discussed.

  15. Active Neural Localization

    OpenAIRE

    Chaplot, Devendra Singh; Parisotto, Emilio; Salakhutdinov, Ruslan

    2018-01-01

    Localization is the problem of estimating the location of an autonomous agent from an observation and a map of the environment. Traditional methods of localization, which filter the belief based on the observations, are sub-optimal in the number of steps required, as they do not decide the actions taken by the agent. We propose "Active Neural Localizer", a fully differentiable neural network that learns to localize accurately and efficiently. The proposed model incorporates ideas of tradition...

  16. Neural cryptography with feedback.

    Science.gov (United States)

    Ruttor, Andreas; Kinzel, Wolfgang; Shacham, Lanir; Kanter, Ido

    2004-04-01

    Neural cryptography is based on a competition between attractive and repulsive stochastic forces. A feedback mechanism is added to neural cryptography which increases the repulsive forces. Using numerical simulations and an analytic approach, the probability of a successful attack is calculated for different model parameters. Scaling laws are derived which show that feedback improves the security of the system. In addition, a network with feedback generates a pseudorandom bit sequence which can be used to encrypt and decrypt a secret message.

  17. Implante de tubo de silicone com e sem colágeno na regeneração de nervos em eqüinos Implant of silicone tube with or without collagen in nerve regeneration of horses

    Directory of Open Access Journals (Sweden)

    Nádia Delistoianov

    2008-09-01

    Full Text Available A reconstituição cirúrgica de nervos em humanos, em cães e em diversos animais de laboratório é bastante utilizada e tem indicações clínicas e experimentais importantes. No entanto, em eqüinos há poucas informações sobre esta prática. Há relatos sobre a excessiva proliferação de tecido conjuntivo e a formação de neuromas à neurorrafia experimental, mesmo quando se utilizam tubos de silicone para condução do crescimento axonal. O presente estudo teve o objetivo de acrescentar informações sobre o processo de reparação de nervos periféricos em eqüinos por meio de implante de tubo de silicone preenchido ou não com colágeno. Para tanto, foram utilizados oito eqüinos, alocados em dois grupos: GI-13 semanas e GII-26 semanas de observação. Foi realizada secção dos nervos ulnares (NUs e dos ramos cutâneos laterais dos 17° nervos torácicos (NTs, bilateralmente, seguindo tubulização, realizada em cada animal, alternando-se tubos de silicone vazios (TS, em um dos antímeros, ou preenchidos com solução de colágeno (TSC, no contralateral, deixando-se um espaço de 5mm entre os cotos. Nenhuma alteração foi encontrada ao exame do aparelho locomotor e as primeiras reações positivas ao teste de sensibilidade cutânea nos NUs e NTs com TS e TSC foram observadas a partir da 9ª semana, em ambos os grupos. Ao final do período de observação, verificou-se, macroscopicamente, que os nervos encontravam-se envolvidos por tecido conjuntivo e o interior da câmara estava preenchido por tecido de coloração esbranquiçada, de forma cilíndrica, interligando os cotos proximal e distal. Microscopicamente, constatou-se a presença de axônios mielinizados interligando os cotos, as células de Schwann e o processo de remielinização do coto distal, principalmente no TSC. Em ambos os grupos, não houve formação de neuromas e o processo inflamatório limitou-se às áreas perineurais. Concluiu-se que o implante de tubo de

  18. The neural basis of bounded rational behavior

    Directory of Open Access Journals (Sweden)

    Coricelli, Giorgio

    2012-03-01

    Full Text Available Bounded rational behaviour is commonly observed in experimental games and in real life situations. Neuroeconomics can help to understand the mental processing underlying bounded rationality and out-of-equilibrium behaviour. Here we report results from recent studies on the neural basis of limited steps of reasoning in a competitive setting —the beauty contest game. We use functional magnetic resonance imaging (fMRI to study the neural correlates of human mental processes in strategic games. We apply a cognitive hierarchy model to classify subject’s choices in the experimental game according to the degree of strategic reasoning so that we can identify the neural substrates of different levels of strategizing. We found a correlation between levels of strategic reasoning and activity in a neural network related to mentalizing, i.e. the ability to think about other’s thoughts and mental states. Moreover, brain data showed how complex cognitive processes subserve the higher level of reasoning about others. We describe how a cognitive hierarchy model fits both behavioural and brain data.

    La racionalidad limitada es un fenómeno observado de manera frecuente tanto en juegos experimentales como en situaciones cotidianas. La Neuroeconomía puede mejorar la comprensión de los procesos mentales que caracterizan la racionalidad limitada; en paralelo nos puede ayudar a comprender comportamientos que violan el equilibrio. Nuestro trabajo presenta resultados recientes sobre la bases neuronales del razonamiento estratégico (y sus límite en juegos competitivos —como el juego del “beauty contest”. Estudiamos las bases neuronales del comportamiento estratégico en juegos con interacción entre sujetos usando resonancia magnética funcional (fMRI. Las decisiones de los participantes se clasifican acorde al grado de razonamiento estratégico: el llamado modelo de Jerarquías Cognitivas. Los resultados muestran una correlación entre niveles de

  19. Wear plates control rod guide tubes top internal reactor vessel C. N. VANDELLOS II; Desgaste placas tubos guia barras de control interno superior vasija del reactor C.N. Vandellos II

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2010-07-01

    The guide tubes for control rods forming part of the upper internals of the reactor vessel, its function is to guide the control rod to permit its insertion in the reactor core. These guide tubes are suspended from the upper support plate which are fixed by bolts and extending to the upper core plate which is fastened by clamping bolts (split pin) to prevent lateral displacement of the guide tubes, while allowing axial expansion.

  20. Problems of interference and geometry of the detectors in a beam tube for the determination of the neutron spectra; Problemas de interferencia y geometria de los detectores en un tubo de haces para la determinacion del espectro de neutrones

    Energy Technology Data Exchange (ETDEWEB)

    Paredes G, L C

    1991-11-15

    The detector materials were selected and proved for the thermal, intermediate and quick energy intervals of the neutron spectra, in the radial tube RW-2 to 1 MW of thermal power during 5 min, being obtained good results respect to the activation of the thin sheets. However, since the exhibition speed, of each experimental arrangement after it irradiation that was of the order of 2 R/h, it was considered that may be more convenient the irradiation, separated from each thin sheet, for that which it was selected the SINCA irradiation system, because it simplified the activities related with the individual irradiation of the thin sheets and the count of the same ones. It was found that the selection, the geometric arrangement and measurement of the activities of the used thin sheets, its are the three factors that more affect the input data of the SAND II code that it will be used in our case for the determination of the neutron spectra of the Reactor. (Author)

  1. Parametric Jominy profiles predictor based on neural networks

    Directory of Open Access Journals (Sweden)

    Valentini, R.

    2005-12-01

    Full Text Available The paper presents a method for the prediction of the Jominy hardness profiles of steels for microalloyed Boron steel which is based on neural networks. The Jominy profile has been parameterized and the parameters, which are a sort of "compact representation" of the profile itself, are linked to the steel chemical composition through a neural network. Numerical results are presented and discussed.

    El trabajo presenta un método de estimación de perfiles de dureza Jominy para aceros microaleados al boro basado en redes neuronales. Los parámetros de perfil Jominy, que constituyen una especie de "representación compacta" del perfil mismo, son determinados y puestos en relación con la composición química del acero mediante una red neuronal. Los resultados numéricos son expuestos y discutidos.

  2. Parallel consensual neural networks.

    Science.gov (United States)

    Benediktsson, J A; Sveinsson, J R; Ersoy, O K; Swain, P H

    1997-01-01

    A new type of a neural-network architecture, the parallel consensual neural network (PCNN), is introduced and applied in classification/data fusion of multisource remote sensing and geographic data. The PCNN architecture is based on statistical consensus theory and involves using stage neural networks with transformed input data. The input data are transformed several times and the different transformed data are used as if they were independent inputs. The independent inputs are first classified using the stage neural networks. The output responses from the stage networks are then weighted and combined to make a consensual decision. In this paper, optimization methods are used in order to weight the outputs from the stage networks. Two approaches are proposed to compute the data transforms for the PCNN, one for binary data and another for analog data. The analog approach uses wavelet packets. The experimental results obtained with the proposed approach show that the PCNN outperforms both a conjugate-gradient backpropagation neural network and conventional statistical methods in terms of overall classification accuracy of test data.

  3. National Pediatric Program Update; Programa Nacional de Actualización Pediátrica

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2008-07-01

    The book of the National Pediatric Program Update, issued by the Argentina Society of Pediatrics, describes important issues, including: effective treatment of addictions (drugs); defects of the neural tube; and the use of radiation imaging in diagnosis. [Spanish] El libro del Programa Nacional de Actualización, editado por la Sociedad Argentina de Pediatría, describe temas de importancia, entre ellos: tratamiento eficaz de las adicciones (drogas); defectos del cierre del tubo neural; y el uso de las radiaciones de diagnóstico por imágenes.

  4. Prevalencia de anticuerpos contra Brucella sp. En donantes del banco de sangre de un hospital de Lima

    Directory of Open Access Journals (Sweden)

    Abel Ortega

    2007-10-01

    Full Text Available El Perú es un país endémico de Brucelosis, por lo que existe el riesgo de transmisión a través de sangre donada por no ser parte del tamizaje regular que realizan los bancos de sangre. Para conocer la prevalencia de anticuerpos contra Brucella en donantes del banco de sangre del Hospital Edgardo Rebagliati Martins, se analizó 1003 muestras de suero. La prueba tamiz fue Rosa de Bengala (RB; las muestras positivas fueron evaluadas por las pruebas de aglutinación en tubo (AT y 2-Mercaptoetanol (2-ME. Dos donantes fueron positivos a RB, confirmados por AT y 2-ME, se encontró una prevalencia de 0,20% (IC99%: 0,01-0,92. Se demostró la presencia de donantes portadores de anticuerpos contra Brucella con posible Brucelosis activa, evidenciándose la posibilidad de transmisión de esta infección. Se debe realizar mayores estudios con la finalidad de conocer la realidad de otros bancos de sangre.

  5. Il dono del racconto

    DEFF Research Database (Denmark)

    Polito, Paola

    1998-01-01

    L'articolo indaga a vari livelli strutturali del romanzo "Il coraggio del pettirosso" (rete metaforica, dialogismo diegetico, dialogismo come fenomeno di voce, strategie discorsive messe in atto dalla voce narrante, stile colloquiale) la complessa realizzazione testuale del genere narrativo...

  6. Reducción del impacto del estrés y prevención de déficits asociados con el envejecimiento en ratas: la estimulación postnatal y el enriquecimiento ambiental

    OpenAIRE

    Ferré, Pilar; Escorihuela, Rosa María; Fernández-Teruel, Albert; Tobeña Pallarés, Adolf; Castellano, Bernardo; González, Berta; Núñez, Joan Francesc; García, Ernesto

    1994-01-01

    Ante situaciones de alarma (o estrés), los organismos desencadenan una serie de reacciones fisiológicas que, si bien son adaptativas, pueden producir a largo plazo efectos nocivos que se relacionan con los procesos neurales del envejecimiento. Se ha hipotetizado que dos manipulaciones efectuadas en las etapas iniciales del desarrollo -el enriquecimiento ambiental y la estimulación postnatal- podrían prevenir o aminorar los déficits cognitivos y neurales asociad...

  7. Neural Architectures for Control

    Science.gov (United States)

    Peterson, James K.

    1991-01-01

    The cerebellar model articulated controller (CMAC) neural architectures are shown to be viable for the purposes of real-time learning and control. Software tools for the exploration of CMAC performance are developed for three hardware platforms, the MacIntosh, the IBM PC, and the SUN workstation. All algorithm development was done using the C programming language. These software tools were then used to implement an adaptive critic neuro-control design that learns in real-time how to back up a trailer truck. The truck backer-upper experiment is a standard performance measure in the neural network literature, but previously the training of the controllers was done off-line. With the CMAC neural architectures, it was possible to train the neuro-controllers on-line in real-time on a MS-DOS PC 386. CMAC neural architectures are also used in conjunction with a hierarchical planning approach to find collision-free paths over 2-D analog valued obstacle fields. The method constructs a coarse resolution version of the original problem and then finds the corresponding coarse optimal path using multipass dynamic programming. CMAC artificial neural architectures are used to estimate the analog transition costs that dynamic programming requires. The CMAC architectures are trained in real-time for each obstacle field presented. The coarse optimal path is then used as a baseline for the construction of a fine scale optimal path through the original obstacle array. These results are a very good indication of the potential power of the neural architectures in control design. In order to reach as wide an audience as possible, we have run a seminar on neuro-control that has met once per week since 20 May 1991. This seminar has thoroughly discussed the CMAC architecture, relevant portions of classical control, back propagation through time, and adaptive critic designs.

  8. Sacred or Neural?

    DEFF Research Database (Denmark)

    Runehov, Anne Leona Cesarine

    Are religious spiritual experiences merely the product of the human nervous system? Anne L.C. Runehov investigates the potential of contemporary neuroscience to explain religious experiences. Following the footsteps of Michael Persinger, Andrew Newberg and Eugene d'Aquili she defines...... the terminological bounderies of "religious experiences" and explores the relevant criteria for the proper evaluation of scientific research, with a particular focus on the validity of reductionist models. Runehov's theis is that the perspectives looked at do not necessarily exclude each other but can be merged....... The question "sacred or neural?" becomes a statement "sacred and neural". The synergies thus produced provide manifold opportunities for interdisciplinary dialogue and research....

  9. Deconvolution using a neural network

    Energy Technology Data Exchange (ETDEWEB)

    Lehman, S.K.

    1990-11-15

    Viewing one dimensional deconvolution as a matrix inversion problem, we compare a neural network backpropagation matrix inverse with LMS, and pseudo-inverse. This is a largely an exercise in understanding how our neural network code works. 1 ref.

  10. Introduction to Artificial Neural Networks

    DEFF Research Database (Denmark)

    Larsen, Jan

    1999-01-01

    The note addresses introduction to signal analysis and classification based on artificial feed-forward neural networks.......The note addresses introduction to signal analysis and classification based on artificial feed-forward neural networks....

  11. Neural Network Ensembles

    DEFF Research Database (Denmark)

    Hansen, Lars Kai; Salamon, Peter

    1990-01-01

    We propose several means for improving the performance an training of neural networks for classification. We use crossvalidation as a tool for optimizing network parameters and architecture. We show further that the remaining generalization error can be reduced by invoking ensembles of similar...... networks....

  12. Neural correlates of consciousness

    African Journals Online (AJOL)

    neural cells.1 Under this approach, consciousness is believed to be a product of the ... possible only when the 40 Hz electrical hum is sustained among the brain circuits, ... expect the brain stem ascending reticular activating system. (ARAS) and the ... related synchrony of cortical neurons.11 Indeed, stimulation of brainstem ...

  13. Neural Networks and Micromechanics

    Science.gov (United States)

    Kussul, Ernst; Baidyk, Tatiana; Wunsch, Donald C.

    The title of the book, "Neural Networks and Micromechanics," seems artificial. However, the scientific and technological developments in recent decades demonstrate a very close connection between the two different areas of neural networks and micromechanics. The purpose of this book is to demonstrate this connection. Some artificial intelligence (AI) methods, including neural networks, could be used to improve automation system performance in manufacturing processes. However, the implementation of these AI methods within industry is rather slow because of the high cost of conducting experiments using conventional manufacturing and AI systems. To lower the cost, we have developed special micromechanical equipment that is similar to conventional mechanical equipment but of much smaller size and therefore of lower cost. This equipment could be used to evaluate different AI methods in an easy and inexpensive way. The proved methods could be transferred to industry through appropriate scaling. In this book, we describe the prototypes of low cost microequipment for manufacturing processes and the implementation of some AI methods to increase precision, such as computer vision systems based on neural networks for microdevice assembly and genetic algorithms for microequipment characterization and the increase of microequipment precision.

  14. Introduction to neural networks

    International Nuclear Information System (INIS)

    Pavlopoulos, P.

    1996-01-01

    This lecture is a presentation of today's research in neural computation. Neural computation is inspired by knowledge from neuro-science. It draws its methods in large degree from statistical physics and its potential applications lie mainly in computer science and engineering. Neural networks models are algorithms for cognitive tasks, such as learning and optimization, which are based on concepts derived from research into the nature of the brain. The lecture first gives an historical presentation of neural networks development and interest in performing complex tasks. Then, an exhaustive overview of data management and networks computation methods is given: the supervised learning and the associative memory problem, the capacity of networks, the Perceptron networks, the functional link networks, the Madaline (Multiple Adalines) networks, the back-propagation networks, the reduced coulomb energy (RCE) networks, the unsupervised learning and the competitive learning and vector quantization. An example of application in high energy physics is given with the trigger systems and track recognition system (track parametrization, event selection and particle identification) developed for the CPLEAR experiment detectors from the LEAR at CERN. (J.S.). 56 refs., 20 figs., 1 tab., 1 appendix

  15. Learning from neural control.

    Science.gov (United States)

    Wang, Cong; Hill, David J

    2006-01-01

    One of the amazing successes of biological systems is their ability to "learn by doing" and so adapt to their environment. In this paper, first, a deterministic learning mechanism is presented, by which an appropriately designed adaptive neural controller is capable of learning closed-loop system dynamics during tracking control to a periodic reference orbit. Among various neural network (NN) architectures, the localized radial basis function (RBF) network is employed. A property of persistence of excitation (PE) for RBF networks is established, and a partial PE condition of closed-loop signals, i.e., the PE condition of a regression subvector constructed out of the RBFs along a periodic state trajectory, is proven to be satisfied. Accurate NN approximation for closed-loop system dynamics is achieved in a local region along the periodic state trajectory, and a learning ability is implemented during a closed-loop feedback control process. Second, based on the deterministic learning mechanism, a neural learning control scheme is proposed which can effectively recall and reuse the learned knowledge to achieve closed-loop stability and improved control performance. The significance of this paper is that the presented deterministic learning mechanism and the neural learning control scheme provide elementary components toward the development of a biologically-plausible learning and control methodology. Simulation studies are included to demonstrate the effectiveness of the approach.

  16. Neural systems for control

    National Research Council Canada - National Science Library

    Omidvar, Omid; Elliott, David L

    1997-01-01

    ... is reprinted with permission from A. Barto, "Reinforcement Learning," Handbook of Brain Theory and Neural Networks, M.A. Arbib, ed.. The MIT Press, Cambridge, MA, pp. 804-809, 1995. Chapter 4, Figures 4-5 and 7-9 and Tables 2-5, are reprinted with permission, from S. Cho, "Map Formation in Proprioceptive Cortex," International Jour...

  17. Neural underpinnings of music

    DEFF Research Database (Denmark)

    Vuust, Peter; Gebauer, Line K; Witek, Maria A G

    2014-01-01

    . According to this theory, perception and learning is manifested through the brain’s Bayesian minimization of the error between the input to the brain and the brain’s prior expectations. Fourth, empirical studies of neural and behavioral effects of syncopation, polyrhythm and groove will be reported, and we...

  18. del cambio

    Directory of Open Access Journals (Sweden)

    Alejandro Canales

    2006-01-01

    Full Text Available El artículo analiza las propuestas y los compromisos en materia de cobertura y de financiamiento en el periodo 2000-2006. En particular, revisa las modificaciones y los ajustes de los tres principales documentos en los que se expresaron las iniciativas: el de la Asociación Nacional de Universidades e Instituciones de Educación Superior, el del equipo de la transición y el programa sectorial. Los resultados muestran que las cifras de atención a la demanda educativa e inversión quedaron lejos de las metas autoimpuestas por el gobierno federal y que será necesario realizar mayores esfuerzos para atender tales desafíos.

  19. Estandarización del ensayo del lisado de amebocitos de Limulus (LAL:: método de gelificación

    Directory of Open Access Journals (Sweden)

    Rolando Perdomo Morales

    2004-04-01

    Full Text Available Entre las principales aplicaciones del método del lisado de amebocitos de Limulus (LAL está el control de endotoxinas en producto final de drogas parenterales. Para la aplicación exitosa del ensayo se requiere del dominio de un conjunto de habilidades, por lo que usualmente se corre en laboratorios especializados que ya cuentan con una basta experiencia. Aunque ya es un método ampliamente establecido y conocido, la aplicación del ensayo puede ser laborioso, consumir tiempo y reactivos hasta la obtención de resultados correctos. En el presente trabajo se describe la estandarización del ensayo del LAL por el método de gelificación. Se evalúan varias estrategias con la finalidad de optimizar y/o reducir el tiempo total de ensayo, el empleo de materiales como puntas certificadas libres de endotoxinas, tubos de ensayo y la sustitución de agua libre de endotoxinas suministrada por los fabricantes de reactivo LAL por agua para inyección. El procedimiento estandarizado produce resultados válidos según los criterios de la Farmacopea de EE.UU.The control of endotoxins in the final product of parenteral drugs is among the main applications of the limulus amebocyte lysate (LAL. For the successful application of this test, it is necessary to have a thorough knowledge of a series of abilities. That's why, it is usually made at specialized laboratories having a vast experience. In spite of the fact that it is already a widely established and known method, the application of the assay may be laborious, take time and consume reagents until the obtention of the right results. In the present paper, it is described the standardization of the LAL assay by the gelification method. Various strategies are evaluated in order to optimize and/or reduce the total time of the assay, the use of materials as certified endotoxin-free points, test tubes, and the substitution of endotoxin-free water, supplied by the manufacturers of LAL reagent, by injection water

  20. Bioprinting for Neural Tissue Engineering.

    Science.gov (United States)

    Knowlton, Stephanie; Anand, Shivesh; Shah, Twisha; Tasoglu, Savas

    2018-01-01

    Bioprinting is a method by which a cell-encapsulating bioink is patterned to create complex tissue architectures. Given the potential impact of this technology on neural research, we review the current state-of-the-art approaches for bioprinting neural tissues. While 2D neural cultures are ubiquitous for studying neural cells, 3D cultures can more accurately replicate the microenvironment of neural tissues. By bioprinting neuronal constructs, one can precisely control the microenvironment by specifically formulating the bioink for neural tissues, and by spatially patterning cell types and scaffold properties in three dimensions. We review a range of bioprinted neural tissue models and discuss how they can be used to observe how neurons behave, understand disease processes, develop new therapies and, ultimately, design replacement tissues. Copyright © 2017 Elsevier Ltd. All rights reserved.

  1. La superaci??n del modelo del ??ngel del hogar:

    OpenAIRE

    Hurtado Mu??oz, M??nica

    2012-01-01

    La Tesis Doctoral titulada "La superaci??n del modelo del "??ngel del hogar". Recuperaci??n de la escritora Leonor Canalejas y Fustegueras (1869-1945)" aborda, en primer lugar, un an??lisis sociol??gico de las circunstancias que rodearon a la mujer espa??ola en el cambio de siglo en el ??mbito social y educativo, en un intento de esclarecer las caracter??sticas propias del contexto en el que la mujer accede a la intelectualidad en general y a la literatura en particular. Esta parte concluye q...

  2. Analysis of neural data

    CERN Document Server

    Kass, Robert E; Brown, Emery N

    2014-01-01

    Continual improvements in data collection and processing have had a huge impact on brain research, producing data sets that are often large and complicated. By emphasizing a few fundamental principles, and a handful of ubiquitous techniques, Analysis of Neural Data provides a unified treatment of analytical methods that have become essential for contemporary researchers. Throughout the book ideas are illustrated with more than 100 examples drawn from the literature, ranging from electrophysiology, to neuroimaging, to behavior. By demonstrating the commonality among various statistical approaches the authors provide the crucial tools for gaining knowledge from diverse types of data. Aimed at experimentalists with only high-school level mathematics, as well as computationally-oriented neuroscientists who have limited familiarity with statistics, Analysis of Neural Data serves as both a self-contained introduction and a reference work.

  3. Structures based on semi-degradable biomaterials for neural regeneration in the central nervous system

    OpenAIRE

    Perez Garnes, Manuel

    2015-01-01

    Se pretende obtener un material semibiodegradable basado en ácido hialurónico químicamente enlazado a cadenas de polímeros acrílicos. Los hidrogeles de ácido hialurónico presentan en general buenas características para su utilización en regeneración del sistema nervioso central: es biodegradable, es un componente importante del tejido neural, sus propiedades mecánicas son semejantes a las del tejido cerebral, promueve la formación de nuevos capilares (angiogénesis), y limita la inflamación. C...

  4. Deep Neural Yodelling

    OpenAIRE

    Pfäffli, Daniel (Autor/in)

    2018-01-01

    Yodel music differs from most other genres by exercising the transition from chest voice to falsetto with an audible glottal stop which is recognised even by laymen. Yodel often consists of a yodeller with a choir accompaniment. In Switzerland, it is differentiated between the natural yodel and yodel songs. Today's approaches to music generation with machine learning algorithms are based on neural networks, which are best described by stacked layers of neurons which are connected with neurons...

  5. Neural networks for triggering

    International Nuclear Information System (INIS)

    Denby, B.; Campbell, M.; Bedeschi, F.; Chriss, N.; Bowers, C.; Nesti, F.

    1990-01-01

    Two types of neural network beauty trigger architectures, based on identification of electrons in jets and recognition of secondary vertices, have been simulated in the environment of the Fermilab CDF experiment. The efficiencies for B's and rejection of background obtained are encouraging. If hardware tests are successful, the electron identification architecture will be tested in the 1991 run of CDF. 10 refs., 5 figs., 1 tab

  6. Artificial neural network modelling

    CERN Document Server

    Samarasinghe, Sandhya

    2016-01-01

    This book covers theoretical aspects as well as recent innovative applications of Artificial Neural networks (ANNs) in natural, environmental, biological, social, industrial and automated systems. It presents recent results of ANNs in modelling small, large and complex systems under three categories, namely, 1) Networks, Structure Optimisation, Robustness and Stochasticity 2) Advances in Modelling Biological and Environmental Systems and 3) Advances in Modelling Social and Economic Systems. The book aims at serving undergraduates, postgraduates and researchers in ANN computational modelling. .

  7. Rotation Invariance Neural Network

    OpenAIRE

    Li, Shiyuan

    2017-01-01

    Rotation invariance and translation invariance have great values in image recognition tasks. In this paper, we bring a new architecture in convolutional neural network (CNN) named cyclic convolutional layer to achieve rotation invariance in 2-D symbol recognition. We can also get the position and orientation of the 2-D symbol by the network to achieve detection purpose for multiple non-overlap target. Last but not least, this architecture can achieve one-shot learning in some cases using thos...

  8. Neural Mechanisms of Foraging

    OpenAIRE

    Kolling, Nils; Behrens, Timothy EJ; Mars, Rogier B; Rushworth, Matthew FS

    2012-01-01

    Behavioural economic studies, involving limited numbers of choices, have provided key insights into neural decision-making mechanisms. By contrast, animals’ foraging choices arise in the context of sequences of encounters with prey/food. On each encounter the animal chooses to engage or whether the environment is sufficiently rich that searching elsewhere is merited. The cost of foraging is also critical. We demonstrate humans can alternate between two modes of choice, comparative decision-ma...

  9. Neural Based Orthogonal Data Fitting The EXIN Neural Networks

    CERN Document Server

    Cirrincione, Giansalvo

    2008-01-01

    Written by three leaders in the field of neural based algorithms, Neural Based Orthogonal Data Fitting proposes several neural networks, all endowed with a complete theory which not only explains their behavior, but also compares them with the existing neural and traditional algorithms. The algorithms are studied from different points of view, including: as a differential geometry problem, as a dynamic problem, as a stochastic problem, and as a numerical problem. All algorithms have also been analyzed on real time problems (large dimensional data matrices) and have shown accurate solutions. Wh

  10. Receptividade do estigma e desenvolvimento do tubo polínico em flores de pessegueiro submetidas à temperatura elevada Stigma receptivity and pollen tube development in peach flowers submitted to high temperature

    Directory of Open Access Journals (Sweden)

    Ilisandra Zanandrea

    2011-12-01

    Full Text Available Dentre os diversos fatores que afetam a produtividade do pessegueiro em regiões subtropicais, está a ocorrência de temperaturas elevadas no início da floração. Tais temperaturas podem causar danos ao estigma e à germinação do grão de pólen, ocasionando decréscimo na fecundação e na fixação dos frutos. O presente trabalho teve por objetivo detectar diferenças entre genótipos quanto à tolerância à temperatura elevada (29±2ºC, bem como verificar se tais diferenças poderiam ser detectadas por um processo simples, utilizando ramos destacados. Para isso, foram realizados dois experimentos, sendo um com ramos destacados e outro com plantas inteiras em vasos, obtidas por enxertia, no outono. As estimativas de graus de receptividade do estigma e de comprimento do tubo polínico nos ramos destacados sugerem que as seleções Conserva 1566 e Conserva 693 e a cv. 'Maciel' não sofrem negativamente influência da temperatura de 29°C. A receptividade do estigma, mesmo em ramos destacados, pode discriminar os genótipos quanto à tolerância da parte feminina a temperaturas próximas a 29°C.Several factors can cause an erratic production of peaches under subtropical conditions. The occurrence of high temperatures on the beginning of blooming is one of them. Such temperatures can damage the stigma and the pollen germination, causing a decrease on fecundation and fruit set. The present work had the objective of looking for differences in tolerance to 29±2ºC among peach genotypes, as well as checking if a simple method using detached twigs would be suitable to detect differences. Two experiments were conducted using whole plants in vase, on one and detached twigs on the other. Estimates of pollen tube growth on the pistil and stigma receptivity suggested that selections Conserva 1566 and Conserva 693 and cv. 'Maciel' were tolerant to temperatures around 29°C at begining of blooming. Stigma receptivity, even in detached twigs, showed

  11. Técnicas de sutura do tubo digestivo em plano único com nós atados no lume, em cães: pontos simples totais versus pontos extramucosos

    Directory of Open Access Journals (Sweden)

    Azevedo João Luiz Moreira Coutinho

    2005-01-01

    Full Text Available OBJETIVO: Comparar a anastomose do tubo digestivo em plano único com nós atados no lume por sutura com pontos totais versus pontos extramucosos. MÉTODOS: Foram operados seis cães, com realização de duas secções transversas do jejuno a 30 cm e a 70 cm da flexura duodenojejunal e sutura, na face posterior com pontos extramucosos atados sobre a submucosa, e na face anterior com pontos totais atados sobre a mucosa. No 7º PO foram avaliadas, na face posterior, as aderências na linha de sutura e feitos exames macroscópico e microscópico. RESULTADOS: As aderências peritoneais foram mais profusas nas suturas extramucosas com tecido aderencial sobre a linha de sutura, sem reconstituição da serosa, ou com a deformidade cicatricial das serosas dos cotos angulando a anastomose. A serosa teve boa reconstituição nas suturas totais. O epitélio mucoso reconstituiu-se perfeitamente nas extramucosas, mas não nas totais. Nas suturas totais houve focos residuais de inflamação aguda.O realinhamento, a reestruturação e a regeneração das camadas (exceto a serosa, cuja regeneração foi prejudicada por aderências foi melhor na sutura extramucosa que na total. A muscular da mucosa não se regenerou em nenhuma anastomose. Os polimorfonucleares, os macrófagos, os fibroblastos e as fibras colágenas foram mais numerosos (significância estatística na sutura total. CONCLUSÃO: As suturas totais da parede posterior da anastomose com nós atados no lume, sobre a mucosa, são seguras, apesar da inflamação maior. A sutura extramucosa da parede posterior, com nós atados no lume, sobre a submucosa, propicia a formação de aderências peritoneais, devendo ser evitada.

  12. Trimaran Resistance Artificial Neural Network

    Science.gov (United States)

    2011-01-01

    11th International Conference on Fast Sea Transportation FAST 2011, Honolulu, Hawaii, USA, September 2011 Trimaran Resistance Artificial Neural Network Richard...Trimaran Resistance Artificial Neural Network 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) 5d. PROJECT NUMBER 5e... Artificial Neural Network and is restricted to the center and side-hull configurations tested. The value in the parametric model is that it is able to

  13. Reactores aeróbios de lecho fluidizado trifásico con circulación interna: caracterización hidrodinámica y del soporte

    Directory of Open Access Journals (Sweden)

    Iván Andrés Sánchez Ortiz

    2010-01-01

    Full Text Available Los reactores aerobios de lecho fluidizado con circulación interna utilizan biomasa activa adherida a un medio soporte (biopelícula, con la ventaja de retener gran concentración de la misma, utilizando poco espacio físico y pudiendo remover, en un mismo reactor, materia carbonácea y nitrogenada. La circulación del líquido ocurre debido a la diferencia de presión hidrostática producida por la inyección de aire en el tubo de subida. En la condición de medio bifásico fueron estudiadas las velocidades de circulación, fracción volumétrica de aire y coeficiente de transferencia de oxígeno, utilizando cuatro configuraciones de reactores. En medio trifásico se evaluaron las velocidades de circulación, la fracción volumétrica de aire y el coeficiente de transferencia de oxígeno en una de dichas configuraciones. También se realizó la caracterización de tres posibles medios de soporte granulares. Se determinó que la relación de áreas entre los tubos interno y externo y la concentración de medio soporte influencian los valores de velocidad de circulación del líquido, de la fracción volumétrica de aire y de la transferencia de oxígeno y se observaron y compararon características importantes de los medios de soporte.

  14. Activación mecánica del caolín como vía para la fabricación de azul ultramar

    Directory of Open Access Journals (Sweden)

    Oscar Jaime Restrepo Baena

    2004-01-01

    Full Text Available La molienda del caolín en molinos de anillos causa una destrucción progresiva de la estructura cristalina original. Los estudios granulométricos demuestran que la molienda de los granos de caolín se produce por fuerzas de cizalladura, ocasionando un deslizamiento de los planos que conforman las partículas, distorsionándolas y aglomerándolas. El estudio de rayos X de mostró una pérdida casi completa de la estructura cristalina. Los análisis de DTA y TGA mostraron que la pérdida del agua de composición interna se produce desde el momento que comienza el calentamiento. Los estudios de microscopía electrónica de barrido muestran granos de forma y tamaño irregular que difieren notablemente de la muestra original. Con las muestras de caolín activado mecánicamente, se fabricó el pigmento Azul Ultramar utilizando un horno de tubo, los resultados obtenidos muestran un producto de características de calidad comparables a los conseguidos utilizando el caolín calcinado (10. Este estudio muestra que la activación mecánica del caolín, puede convertirse en una alternativa a la calcinación, proceso que actualmente se realiza a nivel industrial.

  15. Efecto de las sales fundidas en la termofluencia del acero inoxidable tipo 304

    Directory of Open Access Journals (Sweden)

    González-Rodríguez, G.

    1995-06-01

    Full Text Available Problems caused by both hot corrosion and creep type-damage occurring on superheater and reheater tubes of power plants using heavy oil as fuel shorten their design lives. The acceleration of hot corrosion attack of boilers is caused by the presence of fuel ash deposits containing mainly vanadium, sodium and sulphur, in the form of Na2SO4 y V2O5 and V2O5 which form low melting point compounds. In addition to this, the tubes are exposed to the action of both high stresses and high temperatures, producing the so called creep damage. In this work, creep rupture tests were carried out in the temperature range of 620 to 660 °C in static air and in corrosive environments. The corrosive environments included 100 % Na2SO4, 100 % V2O5 and a 80 % V2O5 + 20 % Na2SO4 mixture.

    Los problemas causados tanto por la corrosión por sales fundidas, así como por la termofluencia en los tubos de los sobrecalentadores y recalentadores de una planta de potencia que usa combustibles fósiles, reducen su vida prevista en diseño. La aceleración de la corrosión por sales fundidas es causada por la presencia de cenizas que contienen principalmente vanadio, sodio y azufre en la forma de Na2SO4 y V2O5, los cuales forman mezclas con eutécticos de bajo punto de fusión. Adicionalmente, los tubos están expuestos a la acción de altos esfuerzos y altas temperaturas, lo cual propicia la termofluencia del material. En este trabajo, se han realizado ensayos de termofluencia hasta la rotura en aire y en ambientes corrosivos en el rango de temperaturas de 620 a 660 °C. Los ambientes corrosivos fueron 100 % Na2SO4, 100 % V2O5, y una mezcla 20 % Na2SO4-80 % V2O5.

  16. Optics in neural computation

    Science.gov (United States)

    Levene, Michael John

    In all attempts to emulate the considerable powers of the brain, one is struck by both its immense size, parallelism, and complexity. While the fields of neural networks, artificial intelligence, and neuromorphic engineering have all attempted oversimplifications on the considerable complexity, all three can benefit from the inherent scalability and parallelism of optics. This thesis looks at specific aspects of three modes in which optics, and particularly volume holography, can play a part in neural computation. First, holography serves as the basis of highly-parallel correlators, which are the foundation of optical neural networks. The huge input capability of optical neural networks make them most useful for image processing and image recognition and tracking. These tasks benefit from the shift invariance of optical correlators. In this thesis, I analyze the capacity of correlators, and then present several techniques for controlling the amount of shift invariance. Of particular interest is the Fresnel correlator, in which the hologram is displaced from the Fourier plane. In this case, the amount of shift invariance is limited not just by the thickness of the hologram, but by the distance of the hologram from the Fourier plane. Second, volume holography can provide the huge storage capacity and high speed, parallel read-out necessary to support large artificial intelligence systems. However, previous methods for storing data in volume holograms have relied on awkward beam-steering or on as-yet non- existent cheap, wide-bandwidth, tunable laser sources. This thesis presents a new technique, shift multiplexing, which is capable of very high densities, but which has the advantage of a very simple implementation. In shift multiplexing, the reference wave consists of a focused spot a few millimeters in front of the hologram. Multiplexing is achieved by simply translating the hologram a few tens of microns or less. This thesis describes the theory for how shift

  17. Embryology of Triatoma infestans (KLUG, (Hemiptera, Reduviidae, a Chagas' disease vector Embriología del Triatoma infestans, vector de la enfermedad de Chagas

    Directory of Open Access Journals (Sweden)

    Laura E. Fichera

    1992-06-01

    Full Text Available This study reports the embryogenesis of T. infestans (Hemiptera, Reduviidae. Morphological parameters of growth sequences from oviposition until hatching (12-14 d 28ºC were established. Five periods, as percent of time of development (TD, were characterized from oviposition until hatching. The most important morphological features were: 1 formation of blastoderm within 7% of TD; 2 germ band and gastrulation within 30% of TD; 3 nerve cord, limb budding, thoracic and abdominal segmentation and formation of body cavity within 50% of TD; 4 nervous system and blastokinesis end, and development of embryonic cuticle within 65% of TD; 5 differentiation of the mouth parts, fat body, and Malphigian tubules during final stage and completion of embryo at day 12 to day 14 around hatching. These signals were chosen as appropriate morphological parameters which should enable the evaluation of embryologic modifications due to the action/s of different insecticidesEn este estudio se caracterizó el desarrollo embrionario del T. infestans (Hemiptera Reduviidae. Se establecieron parámetros morfológicos secuenciales de crecimiento desde la oviposición hasta la eclosión, (12-14 d 28ºC. Cinco períodos de crecimiento fueron determinados y expresados como fracciones porcentuales del tiempo total del desarrollo (TD hasta la eclosión. Los eventos morfológicos mas importantes fueron: 1 La formación del blastodermo hasta el 7% del TD; 2 La aparición de la banda germinativa y su gastrulación transcurridos un 30% del TD; 3 El comienzo de la formación del cordón nervioso, de las extremidades, la segmentación torácica y abdominal y la formación del mixocele cuando la embriogénesis alcanzó el 50% del TD; 4 La terminación de la blastoquinesis, el desarrollo completo del sistema nervioso y la aparición de la cutícula embrionaria hasta el 65% del TD; 5 En la etapa final de la embriogenesis se observó la diferenciación del aparato mandibular, el cuerpo graso

  18. Acerca del moho

    Science.gov (United States)

    El moho forma parte del medio ambiente natural. Afuera del hogar, el moho juega un papel en la naturaleza al desintegrar materias organicas tales como las hojas que se han caido o los arboles muertos. El moho puede crecer adentro del hogar cuando las espor

  19. Del bit al qubit

    OpenAIRE

    Torras Font, Josep

    2011-01-01

    Aquest document pretén donar una visió del desenvolupament dels computadors electrònics i dels components que els han fet possibles. Dintre de les opcions de futur en computació, també intenta donar una visió de les bases en que es fonamenta la computació quàntica.

  20. State of the art of technologies thermosolar to concentration; Estado del arte de las tecnologias termosolares a concentracion

    Energy Technology Data Exchange (ETDEWEB)

    Ramos Berume, Carlos; Huacuz Villamar, Jorge M; Medrano Vaca, M. Consolacion [Instituto de Investigaciones Electricas, Temixco, Morelos (Mexico)

    2000-07-01

    focal (tubo metalico receptor). Por el interior de este tubo circula un fluido de trabajo (aceite termico) a temperaturas de hasta 390 grados Celsius, el cual es enviado a intercambiadores de calor para producir vapor sobrecalentado para operar una turbina y generar la energia electrica y Plato Parabolico (PP), contiene una estructura formada por segmentos de espejos que conforman un paraboloide donde en su punto focal (receptor/maquina termica) incide en la radiacion reflejada y se produce energia electrica. En este documento se presenta el estado del arte de las Tecnologias Termosolares a Concentracion (YYC) que permiten identificar sus desarrollos y problematica actual. Ademas, se incluye una descripcion de las perspectivas de mercado, costos de las TTC y las perspectivas tecnologicas.

  1. Analysis of neural networks

    CERN Document Server

    Heiden, Uwe

    1980-01-01

    The purpose of this work is a unified and general treatment of activity in neural networks from a mathematical pOint of view. Possible applications of the theory presented are indica­ ted throughout the text. However, they are not explored in de­ tail for two reasons : first, the universal character of n- ral activity in nearly all animals requires some type of a general approach~ secondly, the mathematical perspicuity would suffer if too many experimental details and empirical peculiarities were interspersed among the mathematical investigation. A guide to many applications is supplied by the references concerning a variety of specific issues. Of course the theory does not aim at covering all individual problems. Moreover there are other approaches to neural network theory (see e.g. Poggio-Torre, 1978) based on the different lev­ els at which the nervous system may be viewed. The theory is a deterministic one reflecting the average be­ havior of neurons or neuron pools. In this respect the essay is writt...

  2. Neural Synchronization and Cryptography

    Science.gov (United States)

    Ruttor, Andreas

    2007-11-01

    Neural networks can synchronize by learning from each other. In the case of discrete weights full synchronization is achieved in a finite number of steps. Additional networks can be trained by using the inputs and outputs generated during this process as examples. Several learning rules for both tasks are presented and analyzed. In the case of Tree Parity Machines synchronization is much faster than learning. Scaling laws for the number of steps needed for full synchronization and successful learning are derived using analytical models. They indicate that the difference between both processes can be controlled by changing the synaptic depth. In the case of bidirectional interaction the synchronization time increases proportional to the square of this parameter, but it grows exponentially, if information is transmitted in one direction only. Because of this effect neural synchronization can be used to construct a cryptographic key-exchange protocol. Here the partners benefit from mutual interaction, so that a passive attacker is usually unable to learn the generated key in time. The success probabilities of different attack methods are determined by numerical simulations and scaling laws are derived from the data. They show that the partners can reach any desired level of security by just increasing the synaptic depth. Then the complexity of a successful attack grows exponentially, but there is only a polynomial increase of the effort needed to generate a key. Further improvements of security are possible by replacing the random inputs with queries generated by the partners.

  3. Neural Networks for Optimal Control

    DEFF Research Database (Denmark)

    Sørensen, O.

    1995-01-01

    Two neural networks are trained to act as an observer and a controller, respectively, to control a non-linear, multi-variable process.......Two neural networks are trained to act as an observer and a controller, respectively, to control a non-linear, multi-variable process....

  4. Neural networks at the Tevatron

    International Nuclear Information System (INIS)

    Badgett, W.; Burkett, K.; Campbell, M.K.; Wu, D.Y.; Bianchin, S.; DeNardi, M.; Pauletta, G.; Santi, L.; Caner, A.; Denby, B.; Haggerty, H.; Lindsey, C.S.; Wainer, N.; Dall'Agata, M.; Johns, K.; Dickson, M.; Stanco, L.; Wyss, J.L.

    1992-10-01

    This paper summarizes neural network applications at the Fermilab Tevatron, including the first online hardware application in high energy physics (muon tracking): the CDF and DO neural network triggers; offline quark/gluon discrimination at CDF; ND a new tool for top to multijets recognition at CDF

  5. Neural Networks for the Beginner.

    Science.gov (United States)

    Snyder, Robin M.

    Motivated by the brain, neural networks are a right-brained approach to artificial intelligence that is used to recognize patterns based on previous training. In practice, one would not program an expert system to recognize a pattern and one would not train a neural network to make decisions from rules; but one could combine the best features of…

  6. Neural fields theory and applications

    CERN Document Server

    Graben, Peter; Potthast, Roland; Wright, James

    2014-01-01

    With this book, the editors present the first comprehensive collection in neural field studies, authored by leading scientists in the field - among them are two of the founding-fathers of neural field theory. Up to now, research results in the field have been disseminated across a number of distinct journals from mathematics, computational neuroscience, biophysics, cognitive science and others. Starting with a tutorial for novices in neural field studies, the book comprises chapters on emergent patterns, their phase transitions and evolution, on stochastic approaches, cortical development, cognition, robotics and computation, large-scale numerical simulations, the coupling of neural fields to the electroencephalogram and phase transitions in anesthesia. The intended readership are students and scientists in applied mathematics, theoretical physics, theoretical biology, and computational neuroscience. Neural field theory and its applications have a long-standing tradition in the mathematical and computational ...

  7. Artificial neural networks in NDT

    International Nuclear Information System (INIS)

    Abdul Aziz Mohamed

    2001-01-01

    Artificial neural networks, simply known as neural networks, have attracted considerable interest in recent years largely because of a growing recognition of the potential of these computational paradigms as powerful alternative models to conventional pattern recognition or function approximation techniques. The neural networks approach is having a profound effect on almost all fields, and has been utilised in fields Where experimental inter-disciplinary work is being carried out. Being a multidisciplinary subject with a broad knowledge base, Nondestructive Testing (NDT) or Nondestructive Evaluation (NDE) is no exception. This paper explains typical applications of neural networks in NDT/NDE. Three promising types of neural networks are highlighted, namely, back-propagation, binary Hopfield and Kohonen's self-organising maps. (Author)

  8. Análisis y solución de avería del acoplamiento del sinfín de fondo de la Bañera de una Planta de Plástico Mixto. // Analysis and solution of the coupling failure of the bottom worm conveyor of the bathtub in a Mixed Plastic Plant.

    Directory of Open Access Journals (Sweden)

    R. Goytisolo Espinosa

    2004-09-01

    Full Text Available En el trabajo se realizó una investigación para esclarecer las causas de la avería del acoplamiento del sinfín de fondo de labañera de una planta de plástico mixto. En la misma se concluyó que las causas fundamentales de las obstrucciones delsinfín de fondo son el hecho de que el sinfín de elevación de la bañera tiene una capacidad cuatro veces menor que el sinfínde fondo, lo que provoca que el material se acumule en el fondo de la bañera y por otro lado la comunicación entre el sinfínde fondo y el de elevación se produce a través de un tubo vertical de capacidad reducida, que constituye también un cuellode botella. Se modificó la relación de transmisión de la cadena del accionamiento del sinfín de elevación para elevar suvelocidad e igualar la capacidad de transportación de ambos sinfines y se eliminó el tubo de conexión entre los mismos. Elacoplamiento se fabricó de plástico poliamídico, lográndose una adecuada resistencia.Palabras claves: Bañera de plástico, transportadores sinfín, acoplamiento dentado.___________________________________________________________________________Abstract.In this paper is shown the investigation carried out in order to clarify the failure causes of the coupling of the bottom wormconveyor of the bathtub in a Mixed Plastic Plant. In the same was it was concluded that the fundamental causes of theobstructions of the bottom conveyor are the fact that the elevator worm conveyor of the bathtub has a capacity four timesminor that the bottom conveyor, which causes that the material accumulates in the bottom of the bathtub, and on the otherhand the communication between the bottom conveyor and the elevator one takes place through a vertical tube of reducedcapacity that also constitutes a bottle neck. The transmission relationship of the chain of the elevator working conveyor wasmodified in order to elevate their speed and to equal the capacity of transportation of both conveyors, and the

  9. Interacting neural networks

    Science.gov (United States)

    Metzler, R.; Kinzel, W.; Kanter, I.

    2000-08-01

    Several scenarios of interacting neural networks which are trained either in an identical or in a competitive way are solved analytically. In the case of identical training each perceptron receives the output of its neighbor. The symmetry of the stationary state as well as the sensitivity to the used training algorithm are investigated. Two competitive perceptrons trained on mutually exclusive learning aims and a perceptron which is trained on the opposite of its own output are examined analytically. An ensemble of competitive perceptrons is used as decision-making algorithms in a model of a closed market (El Farol Bar problem or the Minority Game. In this game, a set of agents who have to make a binary decision is considered.); each network is trained on the history of minority decisions. This ensemble of perceptrons relaxes to a stationary state whose performance can be better than random.

  10. Neural circuitry and immunity

    Science.gov (United States)

    Pavlov, Valentin A.; Tracey, Kevin J.

    2015-01-01

    Research during the last decade has significantly advanced our understanding of the molecular mechanisms at the interface between the nervous system and the immune system. Insight into bidirectional neuroimmune communication has characterized the nervous system as an important partner of the immune system in the regulation of inflammation. Neuronal pathways, including the vagus nerve-based inflammatory reflex are physiological regulators of immune function and inflammation. In parallel, neuronal function is altered in conditions characterized by immune dysregulation and inflammation. Here, we review these regulatory mechanisms and describe the neural circuitry modulating immunity. Understanding these mechanisms reveals possibilities to use targeted neuromodulation as a therapeutic approach for inflammatory and autoimmune disorders. These findings and current clinical exploration of neuromodulation in the treatment of inflammatory diseases defines the emerging field of Bioelectronic Medicine. PMID:26512000

  11. Neural Darwinism and consciousness.

    Science.gov (United States)

    Seth, Anil K; Baars, Bernard J

    2005-03-01

    Neural Darwinism (ND) is a large scale selectionist theory of brain development and function that has been hypothesized to relate to consciousness. According to ND, consciousness is entailed by reentrant interactions among neuronal populations in the thalamocortical system (the 'dynamic core'). These interactions, which permit high-order discriminations among possible core states, confer selective advantages on organisms possessing them by linking current perceptual events to a past history of value-dependent learning. Here, we assess the consistency of ND with 16 widely recognized properties of consciousness, both physiological (for example, consciousness is associated with widespread, relatively fast, low amplitude interactions in the thalamocortical system), and phenomenal (for example, consciousness involves the existence of a private flow of events available only to the experiencing subject). While no theory accounts fully for all of these properties at present, we find that ND and its recent extensions fare well.

  12. Caracterização de tubo e adesivo utilizados em tubulações de plástico reforçado com fibras de vidro aplicados em plataformas marítimas Characterization of pipes and adhesives of glassfiber reinforced plastics used in offshore platforms

    Directory of Open Access Journals (Sweden)

    Maikon C. R. Pessanha

    2008-03-01

    Full Text Available Na indústria de exploração e produção de petróleo, principalmente no setor offshore, os plásticos reforçados por fibras de vidro (PRFV têm apresentado grande destaque. Isso se deve à intrínseca capacidade destes de resistir à corrosão em ambientes salinos, bem como serem materiais que apresentam elevada resistência mecânica específica. O presente trabalho buscou caracterizar tubo e adesivo utilizados em plataformas marítimas. Para tanto, as técnicas utilizadas foram: espectroscopia na região do infravermelho com transformada de Fourier (FTIR, análise termogravimétrica (TGA, análise termodinâmico-mecânica (DMTA e temperatura de amolecimento de Vicat. Amostras do tubo de PRFV e dos componentes do adesivo (denominados de A e B foram estudadas individualmente. Além disso, foram confeccionadas misturas, em massa, nas seguintes proporções: 40%A-60%B, 50%A-50%B e 60%A-40%B. Foi possível determinar a composição e a estrutura química dos materiais, além do comportamento mecânico à degradação térmica. Foi verificado que adesivo e tubo apresentaram desempenho satisfatório à temperatura ambiente quanto à degradação e à rigidez. Por outro lado, quando submetido ao calor, principalmente os adesivos, apresentaram queda brusca de desempenho.Glassfiber reinforced plastics (GFRP have been applied in the offshore industry owing to their high resistance to corrosion and high specific mechanical strength. The present work aimed at characterizing pipes and adhesives used in offshore platforms in order to evaluate the thermo-mechanical performance of these materials. The techniques used were: Fourier transform infrared spectroscopy (FTIR, thermogravimetry analysis (TGA, dynamic mechanical thermal analysis (DMTA and Vicat softening temperature. Specimens of GFRP pipe and adhesive components (referred to as A and B were evaluated individually. The adhesive samples were made in the following ratios (% weight: 40%A-60%B, 50%A-50

  13. Candida albicans bucais de crianças com síndrome de Down: comportamento de tubos germinativos, exoenzimas e sensibilidade a toxinas"killer" = Buccal candida albicans of children with down’s syndrome: behavior of germ tubes, exoenzimes and sensibility to killer toxins

    Directory of Open Access Journals (Sweden)

    Ribeiro, Evandro Leão

    2007-01-01

    Full Text Available Baseado na necessidade de melhor compreensão dos mecanismos de colonização e patogenicidade por leveduras de Candida provenientes da cavidade bucal de crianças com Síndrome de Down, o objetivo deste estudo de caso controle foi avaliar a capacidade de produção de tubos germinativos e exoenzimas (aspartil proteinases e fosfolipases por C. albicans bucais e o comportamento frente a toxinas “killer”. Foram empregadas 35 (87,5% cepas de C. albicans bucais de crianças com Síndrome de Down e 10 (12,5% de crianças sem síndrome. A produção de tubos germinativos e a detecção de exoenzimas e sensibilidade a toxinas por isolados de Candida foram realizadas segundo as técnicas de Reynolds-Braude, Ruchel, Prince e Polonelli et al. respectivamente. O teste de Reynolds-Braude mostrou melhor capacidade indutora de formação de tubos germinativos no grupo de crianças com Síndrome de Down. Em ambos grupos teste e controle houve a detecção de exoenzimas, entretanto cepas de C. albicans de crianças com alteração cromossômica apresentaram-se mais aspartil proteolíticas e fosfolipidolítipas. Diferenças estatísticas foram significativas em relação ambas capacidades biológicas anteriormente descritas (teste de Reynolds-Braude e atividade exoenzimática das cepas de Candida (p < 0,05. Biotipagem por toxinas “killer” mostrou maior diversidade de biotipos em crianças com síndrome de Down. Conclui-se que as cepas de C. albicans oriundas da mucosa bucal de crianças com Síndrome de Down apresentaram in vitro uma maior predisposição a colonização e a patogenicidade, além de uma melhor expressividade fenotípica em relação às toxinas “killer”

  14. Temperature and pressure control in the discharge of refrigeration systems cooled by shell and tube condensers; Control de presion y temperatura de descarga en sistemas de refrigeracion enfriados por condensadores de casco y tubo

    Energy Technology Data Exchange (ETDEWEB)

    Fernandez Martinez, R. [Asociacion de Ingenieros Egresados de la Universidad Autonoma Metropolitana, Mexico D. F. (Mexico)

    1995-12-31

    In the selection of a refrigeration equipment, the evaporator and condenser load conditions must be perfectly known, that is, the amount of heat energy that we have to reject from our space to cool in base to the temperature and mass to refrigerate. This situation carries on to the selection of the adequate compressor. But nevertheless the temperature conditions of the environment play an important roll in the behavior of the entire refrigeration system, altering in many cases the working conditions of each one of the components and therefore the functioning of the refrigeration system. This paper presents a method for controlling the behavior of each one of the components of the refrigeration system that perform in accordance with their design characteristics. [Espanol] En la seleccion de un equipo de refrigeracion, se deben conocer perfectamente las condiciones de carga del evaporador y del condensador, es decir la cantidad de calor que debemos de eliminar de nuestro medio a refrigerar, en base a la temperatura y masa a refrigerar. Esta situacion conlleva a la eleccion del compresor adecuado. Mas sin embargo, las condiciones de temperatura ambiente, juegan un papel importante en el comportamiento de todo el sistema de refrigeracion, alterando en muchos casos las condiciones de trabajo de cada uno de los componentes y por ende el funcionamiento del sistema de refrigeracion. El presente trabajo presenta un metodo para controlar el comportamiento de cada uno de los componentes dentro del sistema de refrigeracion para que trabajen de acuerdo a su diseno.

  15. Temperature and pressure control in the discharge of refrigeration systems cooled by shell and tube condensers; Control de presion y temperatura de descarga en sistemas de refrigeracion enfriados por condensadores de casco y tubo

    Energy Technology Data Exchange (ETDEWEB)

    Fernandez Martinez, R [Asociacion de Ingenieros Egresados de la Universidad Autonoma Metropolitana, Mexico D. F. (Mexico)

    1996-12-31

    In the selection of a refrigeration equipment, the evaporator and condenser load conditions must be perfectly known, that is, the amount of heat energy that we have to reject from our space to cool in base to the temperature and mass to refrigerate. This situation carries on to the selection of the adequate compressor. But nevertheless the temperature conditions of the environment play an important roll in the behavior of the entire refrigeration system, altering in many cases the working conditions of each one of the components and therefore the functioning of the refrigeration system. This paper presents a method for controlling the behavior of each one of the components of the refrigeration system that perform in accordance with their design characteristics. [Espanol] En la seleccion de un equipo de refrigeracion, se deben conocer perfectamente las condiciones de carga del evaporador y del condensador, es decir la cantidad de calor que debemos de eliminar de nuestro medio a refrigerar, en base a la temperatura y masa a refrigerar. Esta situacion conlleva a la eleccion del compresor adecuado. Mas sin embargo, las condiciones de temperatura ambiente, juegan un papel importante en el comportamiento de todo el sistema de refrigeracion, alterando en muchos casos las condiciones de trabajo de cada uno de los componentes y por ende el funcionamiento del sistema de refrigeracion. El presente trabajo presenta un metodo para controlar el comportamiento de cada uno de los componentes dentro del sistema de refrigeracion para que trabajen de acuerdo a su diseno.

  16. Algunas aclaraciones acerca del conocimiento del singular.

    Directory of Open Access Journals (Sweden)

    Carlos Llano Cifuentes

    2013-11-01

    Full Text Available Llano tries to explain the main purpose of El Conocimiento del Singular, showing how the individuals about which the book is concerned are basically human individuals: people as decision makers.

  17. Program Helps Simulate Neural Networks

    Science.gov (United States)

    Villarreal, James; Mcintire, Gary

    1993-01-01

    Neural Network Environment on Transputer System (NNETS) computer program provides users high degree of flexibility in creating and manipulating wide variety of neural-network topologies at processing speeds not found in conventional computing environments. Supports back-propagation and back-propagation-related algorithms. Back-propagation algorithm used is implementation of Rumelhart's generalized delta rule. NNETS developed on INMOS Transputer(R). Predefines back-propagation network, Jordan network, and reinforcement network to assist users in learning and defining own networks. Also enables users to configure other neural-network paradigms from NNETS basic architecture. Small portion of software written in OCCAM(R) language.

  18. Artificial Neural Network Analysis System

    Science.gov (United States)

    2001-02-27

    Contract No. DASG60-00-M-0201 Purchase request no.: Foot in the Door-01 Title Name: Artificial Neural Network Analysis System Company: Atlantic... Artificial Neural Network Analysis System 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) Powell, Bruce C 5d. PROJECT NUMBER 5e. TASK NUMBER...34) 27-02-2001 Report Type N/A Dates Covered (from... to) ("DD MON YYYY") 28-10-2000 27-02-2001 Title and Subtitle Artificial Neural Network Analysis

  19. Cooperating attackers in neural cryptography.

    Science.gov (United States)

    Shacham, Lanir N; Klein, Einat; Mislovaty, Rachel; Kanter, Ido; Kinzel, Wolfgang

    2004-06-01

    A successful attack strategy in neural cryptography is presented. The neural cryptosystem, based on synchronization of neural networks by mutual learning, has been recently shown to be secure under different attack strategies. The success of the advanced attacker presented here, called the "majority-flipping attacker," does not decay with the parameters of the model. This attacker's outstanding success is due to its using a group of attackers which cooperate throughout the synchronization process, unlike any other attack strategy known. An analytical description of this attack is also presented, and fits the results of simulations.

  20. Creative-Dynamics Approach To Neural Intelligence

    Science.gov (United States)

    Zak, Michail A.

    1992-01-01

    Paper discusses approach to mathematical modeling of artificial neural networks exhibiting complicated behaviors reminiscent of creativity and intelligence of biological neural networks. Neural network treated as non-Lipschitzian dynamical system - as described in "Non-Lipschitzian Dynamics For Modeling Neural Networks" (NPO-17814). System serves as tool for modeling of temporal-pattern memories and recognition of complicated spatial patterns.

  1. Remoção de nitrogênio de água residuária de produção intensiva de tilápias com recirculação utilizando reator de leito fluidizado com circulação em tubos concêntricos

    OpenAIRE

    Sánchez Ortiz, Iván Andrés [UNESP

    2009-01-01

    O presente projeto de pesquisa avaliou o desempenho de remoção de nitrogênio num sistema de tratamento biológico das águas residuárias de produção intensiva de Tilápia Nilótica com recirculação utilizando decantador horizontal e um reator aeróbio de leito fluidizado com circulação em tubos concêntricos. Utilizou-se como material suporte carvão ativado granular com densidade aparente de 1,64g/cm3 e tamanho efetivo de 0,34mm numa concentração de 80g/L. Foram avaliadas as velocidades de circulaç...

  2. Neural components of altruistic punishment

    Directory of Open Access Journals (Sweden)

    Emily eDu

    2015-02-01

    Full Text Available Altruistic punishment, which occurs when an individual incurs a cost to punish in response to unfairness or a norm violation, may play a role in perpetuating cooperation. The neural correlates underlying costly punishment have only recently begun to be explored. Here we review the current state of research on the neural basis of altruism from the perspectives of costly punishment, emphasizing the importance of characterizing elementary neural processes underlying a decision to punish. In particular, we emphasize three cognitive processes that contribute to the decision to altruistically punish in most scenarios: inequity aversion, cost-benefit calculation, and social reference frame to distinguish self from others. Overall, we argue for the importance of understanding the neural correlates of altruistic punishment with respect to the core computations necessary to achieve a decision to punish.

  3. Neural complexity, dissociation, and schizophrenia

    Czech Academy of Sciences Publication Activity Database

    Bob, P.; Šusta, M.; Chládek, Jan; Glaslová, K.; Fedor-Ferybergh, P.

    2007-01-01

    Roč. 13, č. 10 (2007), HY1-5 ISSN 1234-1010 Institutional research plan: CEZ:AV0Z20650511 Keywords : neural complexity * dissociation * schizophrenia Subject RIV: FH - Neurology Impact factor: 1.607, year: 2007

  4. Neural Networks in Control Applications

    DEFF Research Database (Denmark)

    Sørensen, O.

    The intention of this report is to make a systematic examination of the possibilities of applying neural networks in those technical areas, which are familiar to a control engineer. In other words, the potential of neural networks in control applications is given higher priority than a detailed...... study of the networks themselves. With this end in view the following restrictions have been made: - Amongst numerous neural network structures, only the Multi Layer Perceptron (a feed-forward network) is applied. - Amongst numerous training algorithms, only four algorithms are examined, all...... in a recursive form (sample updating). The simplest is the Back Probagation Error Algorithm, and the most complex is the recursive Prediction Error Method using a Gauss-Newton search direction. - Over-fitting is often considered to be a serious problem when training neural networks. This problem is specifically...

  5. Complex-Valued Neural Networks

    CERN Document Server

    Hirose, Akira

    2012-01-01

    This book is the second enlarged and revised edition of the first successful monograph on complex-valued neural networks (CVNNs) published in 2006, which lends itself to graduate and undergraduate courses in electrical engineering, informatics, control engineering, mechanics, robotics, bioengineering, and other relevant fields. In the second edition the recent trends in CVNNs research are included, resulting in e.g. almost a doubled number of references. The parametron invented in 1954 is also referred to with discussion on analogy and disparity. Also various additional arguments on the advantages of the complex-valued neural networks enhancing the difference to real-valued neural networks are given in various sections. The book is useful for those beginning their studies, for instance, in adaptive signal processing for highly functional sensing and imaging, control in unknown and changing environment, robotics inspired by human neural systems, and brain-like information processing, as well as interdisciplina...

  6. Artificial intelligence: Deep neural reasoning

    Science.gov (United States)

    Jaeger, Herbert

    2016-10-01

    The human brain can solve highly abstract reasoning problems using a neural network that is entirely physical. The underlying mechanisms are only partially understood, but an artificial network provides valuable insight. See Article p.471

  7. Optical Neural Network Classifier Architectures

    National Research Council Canada - National Science Library

    Getbehead, Mark

    1998-01-01

    We present an adaptive opto-electronic neural network hardware architecture capable of exploiting parallel optics to realize real-time processing and classification of high-dimensional data for Air...

  8. Memristor-based neural networks

    International Nuclear Information System (INIS)

    Thomas, Andy

    2013-01-01

    The synapse is a crucial element in biological neural networks, but a simple electronic equivalent has been absent. This complicates the development of hardware that imitates biological architectures in the nervous system. Now, the recent progress in the experimental realization of memristive devices has renewed interest in artificial neural networks. The resistance of a memristive system depends on its past states and exactly this functionality can be used to mimic the synaptic connections in a (human) brain. After a short introduction to memristors, we present and explain the relevant mechanisms in a biological neural network, such as long-term potentiation and spike time-dependent plasticity, and determine the minimal requirements for an artificial neural network. We review the implementations of these processes using basic electric circuits and more complex mechanisms that either imitate biological systems or could act as a model system for them. (topical review)

  9. Sequential neural models with stochastic layers

    DEFF Research Database (Denmark)

    Fraccaro, Marco; Sønderby, Søren Kaae; Paquet, Ulrich

    2016-01-01

    How can we efficiently propagate uncertainty in a latent state representation with recurrent neural networks? This paper introduces stochastic recurrent neural networks which glue a deterministic recurrent neural network and a state space model together to form a stochastic and sequential neural...... generative model. The clear separation of deterministic and stochastic layers allows a structured variational inference network to track the factorization of the model's posterior distribution. By retaining both the nonlinear recursive structure of a recurrent neural network and averaging over...

  10. Psicodrama del duelo.

    OpenAIRE

    José Antonio Espina Barrio; Marisol Filgueira Bouza

    1997-01-01

    La pérdida de rituales agrava y alarga la reacción del duelo. Se define el Psicodrama Antropológico y su intervención en el proceso del duelo. El Psicodrama Focal del Duelo es una psicoterapia breve centrada en el proceso de Duelo. Se comentan varios casos y resultados. Se concluye con un programa sencillo para el duelo en Atención Primaria.

  11. Implantable Neural Interfaces for Sharks

    Science.gov (United States)

    2007-05-01

    technology for recording and stimulating from the auditory and olfactory sensory nervous systems of the awake, swimming nurse shark , G. cirratum (Figures...overlay of the central nervous system of the nurse shark on a horizontal MR image. Implantable Neural Interfaces for Sharks ...Neural Interfaces for Characterizing Population Responses to Odorants and Electrical Stimuli in the Nurse Shark , Ginglymostoma cirratum.” AChemS Abs

  12. What are artificial neural networks?

    DEFF Research Database (Denmark)

    Krogh, Anders

    2008-01-01

    Artificial neural networks have been applied to problems ranging from speech recognition to prediction of protein secondary structure, classification of cancers and gene prediction. How do they work and what might they be good for? Udgivelsesdato: 2008-Feb......Artificial neural networks have been applied to problems ranging from speech recognition to prediction of protein secondary structure, classification of cancers and gene prediction. How do they work and what might they be good for? Udgivelsesdato: 2008-Feb...

  13. Neural networks to formulate special fats

    Directory of Open Access Journals (Sweden)

    Garcia, R. K.

    2012-09-01

    Full Text Available Neural networks are a branch of artificial intelligence based on the structure and development of biological systems, having as its main characteristic the ability to learn and generalize knowledge. They are used for solving complex problems for which traditional computing systems have a low efficiency. To date, applications have been proposed for different sectors and activities. In the area of fats and oils, the use of neural networks has focused mainly on two issues: the detection of adulteration and the development of fatty products. The formulation of fats for specific uses is the classic case of a complex problem where an expert or group of experts defines the proportions of each base, which, when mixed, provide the specifications for the desired product. Some conventional computer systems are currently available to assist the experts; however, these systems have some shortcomings. This article describes in detail a system for formulating fatty products, shortenings or special fats, from three or more components by using neural networks (MIX. All stages of development, including design, construction, training, evaluation, and operation of the network will be outlined.

    Las redes neuronales son una rama de la inteligencia artificial basadas en la estructura y funcionamiento de sistemas biológicos, teniendo como principal característica la capacidad de aprender y generalizar conocimiento. Estas son utilizadas en la resolución de problemas complejos, en los cuales los sistemas computacionales tradicionales presentan una eficiencia baja. Hasta la fecha, han sido propuestas aplicaciones para los más diversos sectores y actividades. En el área de grasas y aceites, la utilización de redes neuronales se ha concentrado principalmente en dos asuntos: la detección de adulteraciones y la formulación de productos grasos. La formulación de grasas para uso específico es el caso clásico de problema complejo donde un experto o grupo de

  14. Fractura triple del complejo suspensorio del hombro

    Directory of Open Access Journals (Sweden)

    Eraclio Delgado Rifá

    2015-06-01

    Full Text Available El complejo suspensorio del hombro es una estructura sumamente importante, compuesta por un anillo de huesos y tejidos blandos. Las lesiones aisladas de este complejo anatómico son frecuentes y no afectan su estabilidad. La interrupción doble conduce a la inestabilidad de esta estructura y usualmente requiere tratamiento quirúrgico. La triple interrupción, por su parte, es sumamente rara y es encontrada en casos de trauma de alta energía a menudo en asociación con otras lesiones. Se presenta una triple lesión del complejo suspensorio del hombro en un paciente de 46 años de edad, con una fractura de la glenoides, del acromion tipo III de Kuhn y de la coracoides tipo II de Ogawa. En este caso, la fractura del acromion fue tratada con fijación percutánea con alambres de Kirschner, por tener asociado lesiones de partes blandas que contraindicaron la reducción abierta. La fractura de la glenoides y de la apófisis coracoides fueron tratadas conservadoramente. Después de 6 meses de evolución, el paciente tuvo un resultado funcional aceptable, con una abducción de 90 grados, los 30 grados de rotación externa y 70 de rotación interna, además asintomático y consolidación de todas las fracturas. A pesar de ser catalogada de una lesión grave del cinturón escapular y estar asociada a otras lesiones se obtuvo un resultado satisfactorio al final del tratamiento.

  15. Tratamiento endovascular del aneurisma de aorta descendente en el adolescente con síndrome de Marfan. Reporte de un caso

    Directory of Open Access Journals (Sweden)

    Juan G. Barrera, MD

    2012-01-01

    Full Text Available Se expone el caso de un adolescente de 14 años de edad, con síndrome de Marfan y antecedente de tres cirugías cardiovasculares previas: valvuloplastia aórtica y mitral a los cinco años y valvuloplastia aórtica y reconstrucción de la aorta torácica con tubo de pericardio bovino a sus diez años. En primer tiempo quirúrgico se realizó reemplazo valvular aórtico por válvula mecánica y valvuloplastia mitral y tricuspidea, y en segundo tiempo quirúrgico, durante la misma hospitalización, exclusión endovascular de aneurisma de aorta descendente asintomático sin complicaciones. Antes del egreso se diagnosticó una endofuga tipo II que se manejó con observación clínica. Luego de un año del procedimiento, los controles clínico y tomográfico son satisfactorios.

  16. Vigencia del Darwinismo

    OpenAIRE

    Lessa, Enrique P

    2009-01-01

    En este ensayo se presenta una revisión histórica del signifcado y legado del darwinismo, con énfasis en el último siglo. La principal conclusión es que la visión darwiniana de la evolución, con las modifcaciones requeridas para dar cuenta de los grandes desarrollos de la disciplina, se ha impuesto y mantiene vigencia en nuestros días. En particular, el papel del azar, la evolución como proceso de “descendencia con modifcación” a lo largo de diversas ramas del árbol de la vida, el pensamiento...

  17. Neural correlates of hate.

    Directory of Open Access Journals (Sweden)

    Semir Zeki

    Full Text Available In this work, we address an important but unexplored topic, namely the neural correlates of hate. In a block-design fMRI study, we scanned 17 normal human subjects while they viewed the face of a person they hated and also faces of acquaintances for whom they had neutral feelings. A hate score was obtained for the object of hate for each subject and this was used as a covariate in a between-subject random effects analysis. Viewing a hated face resulted in increased activity in the medial frontal gyrus, right putamen, bilaterally in premotor cortex, in the frontal pole and bilaterally in the medial insula. We also found three areas where activation correlated linearly with the declared level of hatred, the right insula, right premotor cortex and the right fronto-medial gyrus. One area of deactivation was found in the right superior frontal gyrus. The study thus shows that there is a unique pattern of activity in the brain in the context of hate. Though distinct from the pattern of activity that correlates with romantic love, this pattern nevertheless shares two areas with the latter, namely the putamen and the insula.

  18. neural control system

    International Nuclear Information System (INIS)

    Elshazly, A.A.E.

    2002-01-01

    Automatic power stabilization control is the desired objective for any reactor operation , especially, nuclear power plants. A major problem in this area is inevitable gap between a real plant ant the theory of conventional analysis and the synthesis of linear time invariant systems. in particular, the trajectory tracking control of a nonlinear plant is a class of problems in which the classical linear transfer function methods break down because no transfer function can represent the system over the entire operating region . there is a considerable amount of research on the model-inverse approach using feedback linearization technique. however, this method requires a prices plant model to implement the exact linearizing feedback, for nuclear reactor systems, this approach is not an easy task because of the uncertainty in the plant parameters and un-measurable state variables . therefore, artificial neural network (ANN) is used either in self-tuning control or in improving the conventional rule-based exper system.the main objective of this thesis is to suggest an ANN, based self-learning controller structure . this method is capable of on-line reinforcement learning and control for a nuclear reactor with a totally unknown dynamics model. previously, researches are based on back- propagation algorithm . back -propagation (BP), fast back -propagation (FBP), and levenberg-marquardt (LM), algorithms are discussed and compared for reinforcement learning. it is found that, LM algorithm is quite superior

  19. Influence of neural adaptation on dynamics and equilibrium state of neural activities in a ring neural network

    Science.gov (United States)

    Takiyama, Ken

    2017-12-01

    How neural adaptation affects neural information processing (i.e. the dynamics and equilibrium state of neural activities) is a central question in computational neuroscience. In my previous works, I analytically clarified the dynamics and equilibrium state of neural activities in a ring-type neural network model that is widely used to model the visual cortex, motor cortex, and several other brain regions. The neural dynamics and the equilibrium state in the neural network model corresponded to a Bayesian computation and statistically optimal multiple information integration, respectively, under a biologically inspired condition. These results were revealed in an analytically tractable manner; however, adaptation effects were not considered. Here, I analytically reveal how the dynamics and equilibrium state of neural activities in a ring neural network are influenced by spike-frequency adaptation (SFA). SFA is an adaptation that causes gradual inhibition of neural activity when a sustained stimulus is applied, and the strength of this inhibition depends on neural activities. I reveal that SFA plays three roles: (1) SFA amplifies the influence of external input in neural dynamics; (2) SFA allows the history of the external input to affect neural dynamics; and (3) the equilibrium state corresponds to the statistically optimal multiple information integration independent of the existence of SFA. In addition, the equilibrium state in a ring neural network model corresponds to the statistically optimal integration of multiple information sources under biologically inspired conditions, independent of the existence of SFA.

  20. Evaluación físico-química y microbiológica de la calidad del agua de los ríos Machángara y Monjas de la red hídrica del distrito metropolitano de Quito

    Directory of Open Access Journals (Sweden)

    Andrea Campaña

    2017-05-01

    Full Text Available El presente estudio es una evaluación de la calidad y condición actual del agua de los ríos Machángara y Monjas, se midió parámetros físico-químicos como caudal, pH, temperatura, oxígeno disuelto y Potencial de Óxido Reducción (ORP mediante monitoreo in situ, durante los meses de agosto a noviembre del 2014, y se recolectó muestras de agua para el análisis de parámetros microbiológicos (coliformes totales CT y coliformes fecales CF, aplicando el método de fermentación de tubos múltiples, establecido en el Estándar Métodos (Standard Methods ; los análisis evidenciaron que ambos ríos superan ampliamente los límites permisibles establecidos en el Texto Unificado de Legislación Secundaria Medio Ambiental (TULSMA para coliformes totales y fecales, temperatura y oxígeno disuelto, en el caso del río Monjas; esto impediría su aprovechamiento en actividades pecuarias, agrícolas y de preservación de flora y fauna, se evidenció además un incremento considerable en el caudal de ambos ríos y se observa que el valor de ORP de ambos ríos, es menor al valor óptimo de 650mV; los resultados confirmaron la deficiente calidad del agua de los ríos estudiados, cuyas subcuencas forman parte de la Red Hídrica del Distrito Metropolitano de Quito (DMQ y atraviesan zonas de gran densidad poblacional, recibiendo diariamente descargas domésticas e industriales.

  1. Fractional Hopfield Neural Networks: Fractional Dynamic Associative Recurrent Neural Networks.

    Science.gov (United States)

    Pu, Yi-Fei; Yi, Zhang; Zhou, Ji-Liu

    2017-10-01

    This paper mainly discusses a novel conceptual framework: fractional Hopfield neural networks (FHNN). As is commonly known, fractional calculus has been incorporated into artificial neural networks, mainly because of its long-term memory and nonlocality. Some researchers have made interesting attempts at fractional neural networks and gained competitive advantages over integer-order neural networks. Therefore, it is naturally makes one ponder how to generalize the first-order Hopfield neural networks to the fractional-order ones, and how to implement FHNN by means of fractional calculus. We propose to introduce a novel mathematical method: fractional calculus to implement FHNN. First, we implement fractor in the form of an analog circuit. Second, we implement FHNN by utilizing fractor and the fractional steepest descent approach, construct its Lyapunov function, and further analyze its attractors. Third, we perform experiments to analyze the stability and convergence of FHNN, and further discuss its applications to the defense against chip cloning attacks for anticounterfeiting. The main contribution of our work is to propose FHNN in the form of an analog circuit by utilizing a fractor and the fractional steepest descent approach, construct its Lyapunov function, prove its Lyapunov stability, analyze its attractors, and apply FHNN to the defense against chip cloning attacks for anticounterfeiting. A significant advantage of FHNN is that its attractors essentially relate to the neuron's fractional order. FHNN possesses the fractional-order-stability and fractional-order-sensitivity characteristics.

  2. La luz del origen del universo

    Directory of Open Access Journals (Sweden)

    Casas, Alberto

    2015-10-01

    Full Text Available Penzias and Wilson discovered the cosmic microwave background, a luminous echo of the Big Bang, in 1965. The amount of information encoded in this relic of the early universe is truly extraordinary. At present, the most precise data about the origin and structure of the universe comes from the study of this primordial light, the full potential of which has yet to be explored.En 1965 se descubrió el fondo de radiación de microondas, un eco luminoso de la Gran Explosión (Big Bang. La cantidad de información contenida en esta reliquia del universo primitivo es verdaderamente extraordinaria. En la actualidad los datos más precisos sobre el origen y estructura del universo provienen del estudio de esta luz primigenia, que aún no ha sido explorada en todo su potencial.

  3. Archivo del Duelo

    OpenAIRE

    Ferrera, Tamara

    2010-01-01

    Photos taken from the Archive of Mourning following the March 11 terrorist attacks El Archivo del Duelo. Creación de un archivo etnográfico de los Atentados del 11 de marzo en Madrid. Ministerio de Educación y Ciencia HUM2005-03490.

  4. Displasias del seno

    Directory of Open Access Journals (Sweden)

    Ernesto Andrade Valderrama

    1971-04-01

    Full Text Available En general, las Displasias no se presentan antes de la iniciación del estímulo Gonadal y tienden a desaparecer con el climaterio. Se definen entonces como las afecciones benignas del Seno, de origen endocrino.

  5. Implante de tubo valvulado bioprótese "stentless" em posição aórtica: estudo experimental em ovinos A juvenile sheep model for the stentless bioprostheses implanted as aortic root replacements

    Directory of Open Access Journals (Sweden)

    Paulo César SANTOS

    2002-03-01

    Full Text Available INTRODUÇÃO: O tratamento das lesões valvares representa um grande desafio dentro da cirurgia cardiovascular, pois, até os dias atuais, não temos um substituto ideal para as valvas do coração. As próteses atualmente disponíveis apresentam vantagens e desvantagens; as mecânicas exigem anticoagulação definitiva e as biológicas apresentam baixa durabilidade. Para se chegar a um substituto ideal, são necessárias várias fases, desde a escolha e o preparo do material até o implante em animal de grande porte. Esta última é muito importante, pois a escolha do animal deve ser criteriosa. Ovinos juvenís são animais dóceis de fácil manipulação e suas características anatômicas e biológicas se assemelham muito ao que ocorre com o ser humano e as próteses "stentless" são substitutos mais próximos dos homoenxertos. MATERIAL E MÉTODO: Foram operados 30 ovinos juvenís com idade variando de 4,4 a 6,3 meses, peso de 25 a 37 kg, sendo 28 machos. Todos os animais foram submetidos a circulação extracorpórea para implante de bioprótese "stentless" montada em tubo de aorta porcina, com reimplante de artérias coronárias. A operação foi realizada com hipotermia moderada e cardioplegia gelada. O período de seguimento foi de 30 dias e, ao final, realizado ecocardiograma. RESULTADOS: Houve 8 (26,6% óbitos no intra-operatório e 6 (27,7% óbitos no seguimento. O tempo médio de CEC foi de 98 min. Foi realizado ecocardiograma em 16 animais e em nenhum caso foram vistos sinais de endocardite ou outras alterações; a fração média de ejeção foi de 74%. CONCLUSÃO: Este modelo experimental utilizando ovinos para o estudo de biopróteses "stentless" em posição aórtica mostrou-se bem reprodutível e a performance do enxerto bastante factível de ser avaliada, pois ovinos são animais dóceis e de fácil manipulação no seguimento tardio.INTRODUCTION: Often, studies on aortic prosthetic valves analyze their performance not at the

  6. Neural network regulation driven by autonomous neural firings

    Science.gov (United States)

    Cho, Myoung Won

    2016-07-01

    Biological neurons naturally fire spontaneously due to the existence of a noisy current. Such autonomous firings may provide a driving force for network formation because synaptic connections can be modified due to neural firings. Here, we study the effect of autonomous firings on network formation. For the temporally asymmetric Hebbian learning, bidirectional connections lose their balance easily and become unidirectional ones. Defining the difference between reciprocal connections as new variables, we could express the learning dynamics as if Ising model spins interact with each other in magnetism. We present a theoretical method to estimate the interaction between the new variables in a neural system. We apply the method to some network systems and find some tendencies of autonomous neural network regulation.

  7. Actividad antimicótica in vitro y metabolitos del aceite esencial de las hojas de Minthostachys Mollis (muña

    Directory of Open Access Journals (Sweden)

    Carlos Cano

    2008-07-01

    Full Text Available Objetivos. Demostrar la actividad antimicótica in vitro y la elucidación de algunos de los metabolitos del aceite esencial de hojas de Minthostachys mollis (muña proveniente del distrito de Huacrapuquio (2700 msnm, Junín. Materiales y métodos. El aceite esencial se obtuvo por el método de destilación por arrastre de vapor de agua. Este fue sometido a análisis físico-químico y determinación de la composición química mediante cromatografía de gases. Mediante el método de agar en difusión se evaluó la inhibición del crecimiento fúngico de Candida albicans y también por el método de dilución en tubo para Trichophytun tonsurans, Trichophytun mentagrophytes, Microsporun canis. Resultados. Se encontraron los siguientes monoterpenos: pulegona, mentona, limoneno y mirceno. El aceite esencial de muña inhibió completamente el desarrollo de T. tonsurasn, T. mentagrophytes y M. canis con ambos métodos de evaluación y dosis, para C. albicans se logró un halo de inhibición de 30 mm para el aceite esencial al 100% y de 35 mm al 50%. Conclusiones. Se demostró la actividad antimicótica del aceite esencial de muña, probablemente por la acción de los monoterpenos encontrados.

  8. La crisi del diritto del lavoro

    Directory of Open Access Journals (Sweden)

    Alessandro Garilli

    2012-01-01

    Full Text Available Riassunto - L’Autore ripercorre in chiave critica l’evoluzione delle politiche legislative in materia di lavoro, alla luce dell’attuale fase di crisi economico finanziaria. Nell’esaminare i principali interventi normativi attuati da inizio secolo, l’Autore mette in evidenza le scelte di metodo e gli elementi di continuità che accomunano i vari provvedimenti, individuandoli nell’affannosa ricerca del punto di equilibrio tra flessibilità e garantismo. La riflessione si chiude con alcuni interrogativi sulle ultime linee di riforma del mercato del lavoro e con l’auspicio che, anche al cospetto delle imprescindibili ragioni dell’economia, il diritto del lavoro possa continuare a svolgere il proprio tradizionale ruolo di disciplina di tutela della persona.   Abstract - The author analyzes, with a critically oriented approach, the development of the employment law, in the light of the current economic and financial crisis. In examining the main regulatory measures implemented since the beginning of the century, the author highlights the methodological choices and the elements of continuity that unite the various measures, focusing them in a hard research of a point of balance between flexibility and security. The discussion concludes with some questions about the last lines of the reform of the labor market and with the hope that, even in the face of compelling reasons of economy, labor law can continue to play its traditional role of governing the protection of person.

  9. OBJETIVO DEL DESARROLLO DEL MILENIO 7

    Directory of Open Access Journals (Sweden)

    Margarita M. Pérez O.

    2013-10-01

    Full Text Available Los Objetivos de Desarrollo del Milenio, también conocidos como los Objetivos del Milenio, constituyeron las metas finales que aprobaron los dirigentes mundiales, 189 jefes de estado y de gobierno en la Cumbre del Milenio de las Naciones Unidas celebrada en Nueva York en el año 2000, en la cual los Estados miembros de la organización reafirmaron su compromiso de luchar por un mundo en el que el desarrollo sostenible y la eliminación de la pobreza tuvieran máxima prioridad1 . En la cumbre se definió la Declaración del Milenio, la cual detalla los objetivos, principios, valores, metas y acciones para erradicar la pobreza Mundial hacia el año 2015, todos ellos ratificados con alto interés y acción estratégica de carácter global, como marco para la medición de los progresos en materia de desarrollo.

  10. Elementos del sistema electoral del Congreso Mexicano

    Directory of Open Access Journals (Sweden)

    Aldo Medina García

    2013-08-01

    Full Text Available El presente artículo es un estudio de los componentes del sistema electoral, diseñado por el legislador mexicano para integrar al parlamento federal. Estudio desarrollado a sabiendas de la importancia que reviste el sistema electoral como un medio que permite a los ciudadanos convertir su voto expresado en las urnas en escaños a favor de determinado candidato o partido. En dicho análisis tomamos en cuenta la evolución constitucional del sistema electoral mexicano, la participación de las fuerzas minoritarias en la integración del Senado y de la Cámara de Diputados, la división que se hace del territorio en circunscripciones electorales, la barrera electoral que se fija a los partidos políticos para acceder a la representación en el Parlamento, la fórmula de asignación que se aplica a la votación obtenida, para finalmente concluir que el sistema electoral mexicano es esencialmente mayoritario aun cuando se vista de proporcional.

  11. Neural networks and statistical learning

    CERN Document Server

    Du, Ke-Lin

    2014-01-01

    Providing a broad but in-depth introduction to neural network and machine learning in a statistical framework, this book provides a single, comprehensive resource for study and further research. All the major popular neural network models and statistical learning approaches are covered with examples and exercises in every chapter to develop a practical working understanding of the content. Each of the twenty-five chapters includes state-of-the-art descriptions and important research results on the respective topics. The broad coverage includes the multilayer perceptron, the Hopfield network, associative memory models, clustering models and algorithms, the radial basis function network, recurrent neural networks, principal component analysis, nonnegative matrix factorization, independent component analysis, discriminant analysis, support vector machines, kernel methods, reinforcement learning, probabilistic and Bayesian networks, data fusion and ensemble learning, fuzzy sets and logic, neurofuzzy models, hardw...

  12. Neural networks in signal processing

    International Nuclear Information System (INIS)

    Govil, R.

    2000-01-01

    Nuclear Engineering has matured during the last decade. In research and design, control, supervision, maintenance and production, mathematical models and theories are used extensively. In all such applications signal processing is embedded in the process. Artificial Neural Networks (ANN), because of their nonlinear, adaptive nature are well suited to such applications where the classical assumptions of linearity and second order Gaussian noise statistics cannot be made. ANN's can be treated as nonparametric techniques, which can model an underlying process from example data. They can also adopt their model parameters to statistical change with time. Algorithms in the framework of Neural Networks in Signal processing have found new applications potentials in the field of Nuclear Engineering. This paper reviews the fundamentals of Neural Networks in signal processing and their applications in tasks such as recognition/identification and control. The topics covered include dynamic modeling, model based ANN's, statistical learning, eigen structure based processing and generalization structures. (orig.)

  13. Principles of neural information processing

    CERN Document Server

    Seelen, Werner v

    2016-01-01

    In this fundamental book the authors devise a framework that describes the working of the brain as a whole. It presents a comprehensive introduction to the principles of Neural Information Processing as well as recent and authoritative research. The books´ guiding principles are the main purpose of neural activity, namely, to organize behavior to ensure survival, as well as the understanding of the evolutionary genesis of the brain. Among the developed principles and strategies belong self-organization of neural systems, flexibility, the active interpretation of the world by means of construction and prediction as well as their embedding into the world, all of which form the framework of the presented description. Since, in brains, their partial self-organization, the lifelong adaptation and their use of various methods of processing incoming information are all interconnected, the authors have chosen not only neurobiology and evolution theory as a basis for the elaboration of such a framework, but also syst...

  14. Modelo no lineal basado en redes neuronales de unidades producto para clasificación. Una aplicación a la determinación del riesgo en tarjetas de crédito||Non-linear model for classification based on product-unit neural networks. An application to determine credit card risk

    Directory of Open Access Journals (Sweden)

    Martínez-Estudillo, F. J.

    2007-01-01

    Full Text Available El principal objetivo de este trabajo es mostrar un tipo de redes neuronales denominadas redes neuronales basadas en unidades producto (RNUP como un modelo no lineal que puede ser utilizado para la resolución de problemas de clasificación en aprendizaje. Proponemos un método evolutivo en el que simultáneamente se diseña la estructura de la red y se calculan los correspondientes pesos. La metodología que presentamos se basa, por tanto, en la combinación del modelo no lineal RNUP y del algoritmo evolutivo; se aplica a la resolución de un problema de clasificación de índole económica, surgido del mundo de las finanzas. Para evaluar el rendimiento de los modelos de clasificación obtenidos, comparamos nuestra propuesta con varias técnicas clásicas, como la regresión logística o el análisis discriminante, y con el clásico modelo de perceptrón multicapa de redes neuronales basado en unidades sigmoides y el algoritmo de aprendizaje de retropropagación (MLPBP.

  15. Neural Decoder for Topological Codes

    Science.gov (United States)

    Torlai, Giacomo; Melko, Roger G.

    2017-07-01

    We present an algorithm for error correction in topological codes that exploits modern machine learning techniques. Our decoder is constructed from a stochastic neural network called a Boltzmann machine, of the type extensively used in deep learning. We provide a general prescription for the training of the network and a decoding strategy that is applicable to a wide variety of stabilizer codes with very little specialization. We demonstrate the neural decoder numerically on the well-known two-dimensional toric code with phase-flip errors.

  16. Entropy Learning in Neural Network

    Directory of Open Access Journals (Sweden)

    Geok See Ng

    2017-12-01

    Full Text Available In this paper, entropy term is used in the learning phase of a neural network.  As learning progresses, more hidden nodes get into saturation.  The early creation of such hidden nodes may impair generalisation.  Hence entropy approach is proposed to dampen the early creation of such nodes.  The entropy learning also helps to increase the importance of relevant nodes while dampening the less important nodes.  At the end of learning, the less important nodes can then be eliminated to reduce the memory requirements of the neural network.

  17. The neural cell adhesion molecule

    DEFF Research Database (Denmark)

    Berezin, V; Bock, E; Poulsen, F M

    2000-01-01

    During the past year, the understanding of the structure and function of neural cell adhesion has advanced considerably. The three-dimensional structures of several of the individual modules of the neural cell adhesion molecule (NCAM) have been determined, as well as the structure of the complex...... between two identical fragments of the NCAM. Also during the past year, a link between homophilic cell adhesion and several signal transduction pathways has been proposed, connecting the event of cell surface adhesion to cellular responses such as neurite outgrowth. Finally, the stimulation of neurite...

  18. Antenna analysis using neural networks

    Science.gov (United States)

    Smith, William T.

    1992-01-01

    Conventional computing schemes have long been used to analyze problems in electromagnetics (EM). The vast majority of EM applications require computationally intensive algorithms involving numerical integration and solutions to large systems of equations. The feasibility of using neural network computing algorithms for antenna analysis is investigated. The ultimate goal is to use a trained neural network algorithm to reduce the computational demands of existing reflector surface error compensation techniques. Neural networks are computational algorithms based on neurobiological systems. Neural nets consist of massively parallel interconnected nonlinear computational elements. They are often employed in pattern recognition and image processing problems. Recently, neural network analysis has been applied in the electromagnetics area for the design of frequency selective surfaces and beam forming networks. The backpropagation training algorithm was employed to simulate classical antenna array synthesis techniques. The Woodward-Lawson (W-L) and Dolph-Chebyshev (D-C) array pattern synthesis techniques were used to train the neural network. The inputs to the network were samples of the desired synthesis pattern. The outputs are the array element excitations required to synthesize the desired pattern. Once trained, the network is used to simulate the W-L or D-C techniques. Various sector patterns and cosecant-type patterns (27 total) generated using W-L synthesis were used to train the network. Desired pattern samples were then fed to the neural network. The outputs of the network were the simulated W-L excitations. A 20 element linear array was used. There were 41 input pattern samples with 40 output excitations (20 real parts, 20 imaginary). A comparison between the simulated and actual W-L techniques is shown for a triangular-shaped pattern. Dolph-Chebyshev is a different class of synthesis technique in that D-C is used for side lobe control as opposed to pattern

  19. Arabic Handwriting Recognition Using Neural Network Classifier

    African Journals Online (AJOL)

    pc

    2018-03-05

    Mar 5, 2018 ... an OCR using Neural Network classifier preceded by a set of preprocessing .... Artificial Neural Networks (ANNs), which we adopt in this research, consist of ... advantage and disadvantages of each technique. In [9],. Khemiri ...

  20. Neural overlap in processing music and speech.

    Science.gov (United States)

    Peretz, Isabelle; Vuvan, Dominique; Lagrois, Marie-Élaine; Armony, Jorge L

    2015-03-19

    Neural overlap in processing music and speech, as measured by the co-activation of brain regions in neuroimaging studies, may suggest that parts of the neural circuitries established for language may have been recycled during evolution for musicality, or vice versa that musicality served as a springboard for language emergence. Such a perspective has important implications for several topics of general interest besides evolutionary origins. For instance, neural overlap is an important premise for the possibility of music training to influence language acquisition and literacy. However, neural overlap in processing music and speech does not entail sharing neural circuitries. Neural separability between music and speech may occur in overlapping brain regions. In this paper, we review the evidence and outline the issues faced in interpreting such neural data, and argue that converging evidence from several methodologies is needed before neural overlap is taken as evidence of sharing. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

  1. Application of neural networks in coastal engineering

    Digital Repository Service at National Institute of Oceanography (India)

    Mandal, S.

    the neural network attractive. A neural network is an information processing system modeled on the structure of the dynamic process. It can solve the complex/nonlinear problems quickly once trained by operating on problems using an interconnected number...

  2. Ocean wave forecasting using recurrent neural networks

    Digital Repository Service at National Institute of Oceanography (India)

    Mandal, S.; Prabaharan, N.

    , merchant vessel routing, nearshore construction, etc. more efficiently and safely. This paper describes an artificial neural network, namely recurrent neural network with rprop update algorithm and is applied for wave forecasting. Measured ocean waves off...

  3. Neural overlap in processing music and speech

    Science.gov (United States)

    Peretz, Isabelle; Vuvan, Dominique; Lagrois, Marie-Élaine; Armony, Jorge L.

    2015-01-01

    Neural overlap in processing music and speech, as measured by the co-activation of brain regions in neuroimaging studies, may suggest that parts of the neural circuitries established for language may have been recycled during evolution for musicality, or vice versa that musicality served as a springboard for language emergence. Such a perspective has important implications for several topics of general interest besides evolutionary origins. For instance, neural overlap is an important premise for the possibility of music training to influence language acquisition and literacy. However, neural overlap in processing music and speech does not entail sharing neural circuitries. Neural separability between music and speech may occur in overlapping brain regions. In this paper, we review the evidence and outline the issues faced in interpreting such neural data, and argue that converging evidence from several methodologies is needed before neural overlap is taken as evidence of sharing. PMID:25646513

  4. Castillo del Real. Olocau

    OpenAIRE

    AUÑÓN VALLEJO, JONATAN

    2012-01-01

    El objetivo que se quiere alcanzar con este proyecto es el de realizar un estudio lo más cercano posible del Catillo del Real, de manera que se pueda conocer su origen, su evolución a lo largo de la historia, así como las diferentes técnicas y sistemas constructivos utilizados en su construcción. Auñón Vallejo, J. (2011). Castillo del Real. Olocau. http://hdl.handle.net/10251/14244. Archivo delegado

  5. La Representabilidad del Genocidio

    OpenAIRE

    Cardona González, Lorena

    2012-01-01

    El presente artículo intenta hacer una aproximación histórica y analítica al fenómeno del Genocidio, sus implicaciones sociales y culturales que dieron como resultado la reformulación analítica y conceptual de hechos que hasta entonces superaban el conocimiento y la moral humana. De este modo, se hace un trayecto histórico de la paulatina aparición del asesinato masivo como practica de Estado, enmarcado en las experiencias del genocidio armenio y el alemán. A su vez, se hace una mirada sobre ...

  6. Significado presente del CSIC

    OpenAIRE

    Garrido Gallardo, Miguel Angel

    2000-01-01

    Not available

    Este artículo, elaborado en 1999, ofrece una panorámica de la realidad del Consejo Superior de Investigaciones Científicas en la actualidad. Repasa su organización, su volumen de publicaciones, sus indicadores de productividad, su capacidad de obtener recursos y, en suma, su lugar en el conjunto del sistema español de Ciencia y Tecnología, considerado en sí mismo y en relación con la Universidad. Como conclusión del repaso de datos, se afirma que, aunque la fó...

  7. Tratamiento del pie equino

    OpenAIRE

    Robles, Fernanda

    2012-01-01

    El pie equino varo es una patología frecuente en los pacientes con Encefalopatía crónica no evolutiva (ECNE).Se observó que existe una mayor frecuencia en el sexo masculino. Se realizó un estudio descriptivo, comparativo y secundario, durante el periodo de septiembre del 2006 a septiembre del 2011, con un total de 125 pacientes con Ecne, de los cuales se encontraron 101 con pie equino varo congénito. Objetivo: observar los resultados obtenidos en la rehabilitación del pie equino, en niños de ...

  8. Del Pasadismo al Futurismo

    OpenAIRE

    Agudo-Martínez, M. J.

    2003-01-01

    Uno de los habituales prejuicios a la hora de abordar el análisis del movimiento futurista, al igual que sucede con el constructivismo, es la consideración del contexto político en el que se desarrollaron ambas vanguardias. Sin embargo, y dejando a un lado un enfoque del arte con finalidad política de signo diverso, habría que insistir en el hecho de que posiblemente sean tanto el futurismo italiano como el constructivismo ruso, los movimientos que con mayor entusiasmo se manifestaron, en un ...

  9. MEMBRAIN NEURAL NETWORK FOR VISUAL PATTERN RECOGNITION

    Directory of Open Access Journals (Sweden)

    Artur Popko

    2013-06-01

    Full Text Available Recognition of visual patterns is one of significant applications of Artificial Neural Networks, which partially emulate human thinking in the domain of artificial intelligence. In the paper, a simplified neural approach to recognition of visual patterns is portrayed and discussed. This paper is dedicated for investigators in visual patterns recognition, Artificial Neural Networking and related disciplines. The document describes also MemBrain application environment as a powerful and easy to use neural networks’ editor and simulator supporting ANN.

  10. Neural network to diagnose lining condition

    Science.gov (United States)

    Yemelyanov, V. A.; Yemelyanova, N. Y.; Nedelkin, A. A.; Zarudnaya, M. V.

    2018-03-01

    The paper presents data on the problem of diagnosing the lining condition at the iron and steel works. The authors describe the neural network structure and software that are designed and developed to determine the lining burnout zones. The simulation results of the proposed neural networks are presented. The authors note the low learning and classification errors of the proposed neural networks. To realize the proposed neural network, the specialized software has been developed.

  11. Simplified LQG Control with Neural Networks

    DEFF Research Database (Denmark)

    Sørensen, O.

    1997-01-01

    A new neural network application for non-linear state control is described. One neural network is modelled to form a Kalmann predictor and trained to act as an optimal state observer for a non-linear process. Another neural network is modelled to form a state controller and trained to produce...

  12. Analysis of neural networks through base functions

    NARCIS (Netherlands)

    van der Zwaag, B.J.; Slump, Cornelis H.; Spaanenburg, L.

    Problem statement. Despite their success-story, neural networks have one major disadvantage compared to other techniques: the inability to explain comprehensively how a trained neural network reaches its output; neural networks are not only (incorrectly) seen as a "magic tool" but possibly even more

  13. Genetic Algorithm Optimized Neural Networks Ensemble as ...

    African Journals Online (AJOL)

    NJD

    Improvements in neural network calibration models by a novel approach using neural network ensemble (NNE) for the simultaneous ... process by training a number of neural networks. .... Matlab® version 6.1 was employed for building principal component ... provide a fair simulation of calibration data set with some degree.

  14. Recycling signals in the neural crest

    OpenAIRE

    Taneyhill, Lisa A.; Bronner-Fraser, Marianne E.

    2006-01-01

    Vertebrate neural crest cells are multipotent and differentiate into structures that include cartilage and the bones of the face, as well as much of the peripheral nervous system. Understanding how different model vertebrates utilize signaling pathways reiteratively during various stages of neural crest formation and differentiation lends insight into human disorders associated with the neural crest.

  15. Recycling signals in the neural crest.

    Science.gov (United States)

    Taneyhill, Lisa A; Bronner-Fraser, Marianne

    2005-01-01

    Vertebrate neural crest cells are multipotent and differentiate into structures that include cartilage and the bones of the face, as well as much of the peripheral nervous system. Understanding how different model vertebrates utilize signaling pathways reiteratively during various stages of neural crest formation and differentiation lends insight into human disorders associated with the neural crest.

  16. Effects of Fungicides on the Development of the Entomopathogenic Fungus Metarhizium anisopliae var. anisopliae Efecto de los Fungicidas sobre el Desarrollo del Hongo Entomopatógeno Metarhizium anisopliae var. anisopliae

    Directory of Open Access Journals (Sweden)

    Maribel Yáñez

    2010-09-01

    crecimiento se evaluó a través del diámetro de crecimiento de las colonias, considerándose como compatibles a aquellas que superaron el 50% del crecimiento del testigo. Los resultados indicaron que los fungicidas benomyl y fenhexamid fueron compatibles con las cinco cepas, mientras que azoxystrobin y fludioxonil fueron incompatibles con todas las cepas evaluadas. Benomyl y fludioxonil además, disminuyeron (53 a 91% la germinación de conidias para los distintos aislamientos evaluados, así como la longitud de los tubos germinativos entre 18 y 37%.

  17. Preferencias del Turista

    Directory of Open Access Journals (Sweden)

    Jose Luis Leiva Olivencia

    2015-01-01

    Full Text Available Actualmente existen aplicaciones orientadas al turismo basadas en realidad aumentada, pero no integran técnicas de recomendación. Este articulo describe RAMCAT (Realidad Aumentada Móvil Contextual Aplicada al Turismo un modelo de guía turística, que recomienda puntos de interés, teniendo en cuenta factores como preferencias personales y atributos contextuales. Se presentan los componentes teóricos de la arquitectura propuesta, así como sus características, destacando la integración de diferentes sistemas de recomendación, que permiten añadir nuevos motores en el futuro. El articulo se centra en describir sus funcionalidades y el modulo correspondiente al sistema de recomendación basado en el perfil del turista. Otra característica importante del sistema propuesto es la retroalimentación del mismo mediante calificaciones del turista y su trazabilidad.

  18. Carta del Editor

    Directory of Open Access Journals (Sweden)

    Luis Eladio Proaño

    2015-01-01

    Full Text Available La millonaria contratación del futbolista David Beckham, un fenómeno del mercado, ha provocado cuestionamientos a los que se busca respuesta. Es tema de análisis el por qué el betseller "Harry Potter" ha causado tanta conmoción en la opinión pública. Respecto al periodista cibernético, se señalan los contornos del presente y atisban las posibilidades del futuro de esta nueva profesión. El tratamiento de los mitos de la prensa, los temores de la Ley mordaza venezolana y la brutalidad de los video juegos e Internet son temas de enorme interés. Se comenta las pocas veces que la prensa reflexiona sobre la comunicación corporal y la anorexia.

  19. Los muertos del Floreanismo

    Directory of Open Access Journals (Sweden)

    Enrique Ayala Mora

    2008-06-01

    Full Text Available El artículo analiza el crimen político durante las primeras décadas de vida de la República del Ecuador. Específicamente centra su estudio en el período dominado por la figura de Juan José Flores, primer presidente del Ecuador. La inestabilidad política, la precariedad de las alianzas entre las élites regionales, la crisis económica generada por las guerras de Independencia, las conspiraciones y la violencia que caracterizaron al período de surgimiento de las repúblicas andinas hicieron del crimen político un “vicio de nacimiento”. El asesinato del general Antonio José de Sucre, la muerte de los miembros de la sociedad El Quiteño Libre, el homicidio de Juan Otamendi, entre otros, hicieron patente esta característica.

  20. Niveles del aprendizaje organizacional

    OpenAIRE

    Garzón Castrillón, Manuel Alfonso

    2005-01-01

    En la propuesta de modelo de aprendizaje organizacional (AO), la segunda variable se denomina niveles del aprendizaje organizacional ; los niveles de aprendizaje que contemplamos para nuestra investigación son: individual, de equipo, organizacional e interorganizacional.

  1. La escritura del Yo

    Directory of Open Access Journals (Sweden)

    Patricio Landaeta Mardones

    2013-11-01

    Full Text Available Si la creación de una imagen fidedigna del mundo fue la condición de la conquista cognitiva y económica de la tierra, las imágenes mediáticas circulan hoy en día a la manera de un montaje que organiza los sujetos como elementos de un territorio. En esta presentación abordaremos el cruce entre estos dos hechos, entre la escritura del mundo y la de los sujetos, a partir de la idea de Fabulación para mostrar otra escritura del mundo y del yo, leyendo textos e imágenes de la Primera buena Corónica y Buen Gobierno de Felipe Guaman Poma de Ayala.

  2. Consideraciones alrededor del Libro del Almismo, el Libro del Pensar.

    Directory of Open Access Journals (Sweden)

    MartaLucía Tamayo Fernandez

    1999-12-01

    Full Text Available

    La doctora MarthaLucía Tamayo comparte muchas inquietudes alrededor del Libro del Almismo, el Libro del Pensar; de dónde salió ese nombre; de juntar en medicina y en genética a tres escritores como lo son Jorge Luis Borges, Macedonio Fernández y Julio Cortázar. Su conferencia dice así:

    El término almismo fue ideado por Macedonio Fernández porque defendía mucho el ensimismamiento y el pensamiento hacia el interior, mirar hacia adentro; cada uno somos un “sí mismo” que nos hace diferentes aunque al mismo tiempo podemos ser iguales. Todos tenemos esa parte interior que la medicina debe trabajar y que no puede olvidar.

    “El Libro del Almismo, el libro del pensar” nos lleva a replantear y a repensar un poco la medicina que queremos, una medicina vuelta a pensar.

    Quiero contarles la historia de cómo se llegó a este libro y por qué y para qué se sigue trabajando en estos temas: Después de mi internado y de un trabajo un poco triste de rural, volví al Instituto de Genética y a la Universidad Javeriana en donde encontré al doctor Bernal y un espacio que estaba buscando para esa medicina diferente que quería, con un grupo de personas que me permitía no sólo ver la medicina sino ver muchas otras cosas más; había espacio para la literatura, para Mafalda, para hablar de niños, de locos, había incluso tiempo para hablar de medicina dentro del golf, de carros antiguos y de todo eso fui aprendiendo.

    Eso era lo que estaba buscando. Una medicina que diera espacios diferentes, que fuera más humanizada. Rápidamente me ubiqué y me quedé! No me arrepiento en lo absoluto de haberme quedado porque fue, ha sido y sigue siendo, una experiencia enriquecedora, de muchas vivencias importantes. Sabía exactamente dónde estaba y sabía que había que seguir rápido y había que trabajar muchos aspectos de esa medicina que estábamos buscando y de esa genética especial.

    Rápidamente empezamos a trabajar

  3. Neural chips, neural computers and application in high and superhigh energy physics experiments

    International Nuclear Information System (INIS)

    Nikityuk, N.M.; )

    2001-01-01

    Architecture peculiarity and characteristics of series of neural chips and neural computes used in scientific instruments are considered. Tendency of development and use of them in high energy and superhigh energy physics experiments are described. Comparative data which characterize the efficient use of neural chips for useful event selection, classification elementary particles, reconstruction of tracks of charged particles and for search of hypothesis Higgs particles are given. The characteristics of native neural chips and accelerated neural boards are considered [ru

  4. Medical Imaging with Neural Networks

    International Nuclear Information System (INIS)

    Pattichis, C.; Cnstantinides, A.

    1994-01-01

    The objective of this paper is to provide an overview of the recent developments in the use of artificial neural networks in medical imaging. The areas of medical imaging that are covered include : ultrasound, magnetic resonance, nuclear medicine and radiological (including computerized tomography). (authors)

  5. Optoelectronic Implementation of Neural Networks

    Indian Academy of Sciences (India)

    neural networks, such as learning, adapting and copying by means of parallel ... to provide robust recognition of hand-printed English text. Engine idle and misfiring .... and s represents the bounded activation function of a neuron. It is typically ...

  6. Aphasia Classification Using Neural Networks

    DEFF Research Database (Denmark)

    Axer, H.; Jantzen, Jan; Berks, G.

    2000-01-01

    A web-based software model (http://fuzzy.iau.dtu.dk/aphasia.nsf) was developed as an example for classification of aphasia using neural networks. Two multilayer perceptrons were used to classify the type of aphasia (Broca, Wernicke, anomic, global) according to the results in some subtests...

  7. Intelligent neural network diagnostic system

    International Nuclear Information System (INIS)

    Mohamed, A.H.

    2010-01-01

    Recently, artificial neural network (ANN) has made a significant mark in the domain of diagnostic applications. Neural networks are used to implement complex non-linear mappings (functions) using simple elementary units interrelated through connections with adaptive weights. The performance of the ANN is mainly depending on their topology structure and weights. Some systems have been developed using genetic algorithm (GA) to optimize the topology of the ANN. But, they suffer from some limitations. They are : (1) The computation time requires for training the ANN several time reaching for the average weight required, (2) Slowness of GA for optimization process and (3) Fitness noise appeared in the optimization of ANN. This research suggests new issues to overcome these limitations for finding optimal neural network architectures to learn particular problems. This proposed methodology is used to develop a diagnostic neural network system. It has been applied for a 600 MW turbo-generator as a case of real complex systems. The proposed system has proved its significant performance compared to two common methods used in the diagnostic applications.

  8. Medical Imaging with Neural Networks

    Energy Technology Data Exchange (ETDEWEB)

    Pattichis, C [Department of Computer Science, University of Cyprus, Kallipoleos 75, P.O.Box 537, Nicosia (Cyprus); Cnstantinides, A [Department of Electrical Engineering, Imperial College of Science, Technology and Medicine, London SW7 2BT (United Kingdom)

    1994-12-31

    The objective of this paper is to provide an overview of the recent developments in the use of artificial neural networks in medical imaging. The areas of medical imaging that are covered include : ultrasound, magnetic resonance, nuclear medicine and radiological (including computerized tomography). (authors). 61 refs, 4 tabs.

  9. Numerical experiments with neural networks

    International Nuclear Information System (INIS)

    Miranda, Enrique.

    1990-01-01

    Neural networks are highly idealized models which, in spite of their simplicity, reproduce some key features of the real brain. In this paper, they are introduced at a level adequate for an undergraduate computational physics course. Some relevant magnitudes are defined and evaluated numerically for the Hopfield model and a short term memory model. (Author)

  10. Serotonin, neural markers and memory

    Directory of Open Access Journals (Sweden)

    Alfredo eMeneses

    2015-07-01

    Full Text Available Diverse neuropsychiatric disorders present dysfunctional memory and no effective treatment exits for them; likely as result of the absence of neural markers associated to memory. Neurotransmitter systems and signaling pathways have been implicated in memory and dysfunctional memory; however, their role is poorly understood. Hence, neural markers and cerebral functions and dysfunctions are revised. To our knowledge no previous systematic works have been published addressing these issues. The interactions among behavioral tasks, control groups and molecular changes and/or pharmacological effects are mentioned. Neurotransmitter receptors and signaling pathways, during normal and abnormally functioning memory with an emphasis on the behavioral aspects of memory are revised. With focus on serotonin, since as it is a well characterized neurotransmitter, with multiple pharmacological tools, and well characterized downstream signaling in mammals’ species. 5-HT1A, 5-HT4, 5-HT5, 5-HT6 and 5-HT7 receptors as well as SERT (serotonin transporter seem to be useful neural markers and/or therapeutic targets. Certainly, if the mentioned evidence is replicated, then the translatability from preclinical and clinical studies to neural changes might be confirmed. Hypothesis and theories might provide appropriate limits and perspectives of evidence

  11. Neural correlates of viewing paintings

    DEFF Research Database (Denmark)

    Vartanian, Oshin; Skov, Martin

    2014-01-01

    Many studies involving functional magnetic resonance imaging (fMRI) have exposed participants to paintings under varying task demands. To isolate neural systems that are activated reliably across fMRI studies in response to viewing paintings regardless of variation in task demands, a quantitative...

  12. Neural Basis of Visual Distraction

    Science.gov (United States)

    Kim, So-Yeon; Hopfinger, Joseph B.

    2010-01-01

    The ability to maintain focus and avoid distraction by goal-irrelevant stimuli is critical for performing many tasks and may be a key deficit in attention-related problems. Recent studies have demonstrated that irrelevant stimuli that are consciously perceived may be filtered out on a neural level and not cause the distraction triggered by…

  13. Vestibular hearing and neural synchronization.

    Science.gov (United States)

    Emami, Seyede Faranak; Daneshi, Ahmad

    2012-01-01

    Objectives. Vestibular hearing as an auditory sensitivity of the saccule in the human ear is revealed by cervical vestibular evoked myogenic potentials (cVEMPs). The range of the vestibular hearing lies in the low frequency. Also, the amplitude of an auditory brainstem response component depends on the amount of synchronized neural activity, and the auditory nerve fibers' responses have the best synchronization with the low frequency. Thus, the aim of this study was to investigate correlation between vestibular hearing using cVEMPs and neural synchronization via slow wave Auditory Brainstem Responses (sABR). Study Design. This case-control survey was consisted of twenty-two dizzy patients, compared to twenty healthy controls. Methods. Intervention comprised of Pure Tone Audiometry (PTA), Impedance acoustic metry (IA), Videonystagmography (VNG), fast wave ABR (fABR), sABR, and cVEMPs. Results. The affected ears of the dizzy patients had the abnormal findings of cVEMPs (insecure vestibular hearing) and the abnormal findings of sABR (decreased neural synchronization). Comparison of the cVEMPs at affected ears versus unaffected ears and the normal persons revealed significant differences (P < 0.05). Conclusion. Safe vestibular hearing was effective in the improvement of the neural synchronization.

  14. Spin glasses and neural networks

    International Nuclear Information System (INIS)

    Parga, N.; Universidad Nacional de Cuyo, San Carlos de Bariloche

    1989-01-01

    The mean-field theory of spin glass models has been used as a prototype of systems with frustration and disorder. One of the most interesting related systems are models of associative memories. In these lectures we review the main concepts developed to solve the Sherrington-Kirkpatrick model and its application to neural networks. (orig.)

  15. Actualidad del relativismo cultural

    OpenAIRE

    Sánchez Durá, Nicolás

    2013-01-01

    Este ensayo tiene tres propósitos. En primer lugar, propone examinar las relaciones entre etnocentrismo y relativismo. El etnocentrismo puede tomar tres formas distintas: a saber, la de una universalidad impostada, la del exotismo y la de un particularismo narcisista exacerbado. El relativismo cultural es una postura que asume la inconmensurabilidad de los conceptos y valores que deben ser considerados como válidos dentro de las imágenes del mundo definidas. En segundo lugar, se argumenta que...

  16. Estimación de la Incertidumbre en los Ensayos Microbiológicos de Coliformes Totales y Fecales en Aguas Y Aguas Residuales Mediante la Técnica de Tubos Múltiples de Fermentación.

    OpenAIRE

    Marlen Robert Pullés; Rogelio Mayarí Navarro; María del C. Espinosa

    2005-01-01

    En la microbiología ambiental es de vital importancia contar con un control de la calidad, dentro del cual, debe considerarse el método de ensayo para garantizar una óptima calidad de los datos resultantes. El cálculo de la incertidumbre está siendo abordado por la comunidad de laboratorios y se espera que en un futuro se disponga de directrices más claras en este campo. La incertidumbre, como un atributo cuantificable, es un concepto relativamente nuevo en la historia de las mediciones, a pe...

  17. Estimación de La Incertidumbre en los Ensayos Microbiológicos de Coliformes Totalesy Fecales en Aguas y Aguas Residuales mediante La Tecnica de Tubos Múltiples de Fermentación.

    OpenAIRE

    Marlen Robert Pullés; Rogelio Mayarí Navarro; María del C. Espinosa

    2005-01-01

    En la microbiología ambiental es de vital importancia contar con un control de la calidad, dentro del cual, debe considerarse el método de ensayo para garantizar una óptima calidad de los datos resultantes. El cálculo de la incertidumbre está siendo abordado por la comunidad de laboratorios y se espera que en un futuro se disponga de directrices más claras en este campo. La incertidumbre, como un atributo cuantificable, es un concepto relativamente nuevo en la historia de las mediciones, a pe...

  18. Análise do tratamento cirúrgico da raiz da aorta com o tubo valvulado e com a preservação da valva aórtica Analysis of aortic root surgery with composite mechanical aortic valve conduit and valve-sparing reconstruction

    Directory of Open Access Journals (Sweden)

    Ricardo Ribeiro Dias

    2010-12-01

    Full Text Available OBJETIVO: Análise comparativa dos resultados imediatos e tardios da reconstrução da raiz da aorta com o tubo valvulado e com a preservação da valva aórtica. MÉTODOS: No período de novembro de 2002 a setembro de 2009, 164 pacientes com idade média de 54 ± 15 anos, sendo 115 do sexo masculino, foram submetidos ao tratamento cirúrgico da raiz da aorta. Foram 125 tubos valvulados e 39 reconstruções da raiz da aorta com preservação da valva aórtica. Dezesseis por cento dos pacientes eram portadores de síndrome de Marfan e 4,3% apresentavam valva aórtica bivalvulada. Cento e quarenta e quatro (88% pacientes foram acompanhados durante tempo médio de seguimento de 41,1 ± 20,8 meses. RESULTADOS: A mortalidade hospitalar total foi de 4,9%; sendo 5,6% nas operações com tubo valvulado e 2,6% nas preservações da valva aórtica (POBJECTIVE: Comparative analysis of early and late results of aortic root reconstruction with aortic valve sparing operations and the composite mechanical valve conduit replacement. METHODS: From November 2002 to September 2009, 164 consecutive patients with mean age 54 ± 15 years, 115 male, underwent the aortic root reconstruction (125 mechanical valve conduit replacements and 39 valve sparing operations. Sixteen percent of patients had Marfan syndrome and 4.3% had bicuspid aortic valve. One hundred and forty-four patients (88% were followed for a mean period of 41.1 ± 20.8 months. RESULTS: The hospital mortality was 4.9%, 5.6% in operations with valved conduits and 2.6% in the valve sparing procedures (P <0.05. There was no difference neither in survival (95% CI = 86% - 96%, P= 0.1 nor in reoperation-free survival (95% CI = 85% - 90%, P = 0.29. The survival free of complications such as bleeding, thromboembolism and endocarditis were favorable to the valve sparing operations, respectively (95% CI = 70% - 95%, P = 0.001, (95% CI = 82% - 95% P = 0.03 and (95% CI = 81% - 95%, P = 0.03. Multivariate analysis

  19. el Valle del Cauca

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    Carlos Humberto Ortiz

    2007-01-01

    Full Text Available Este artículo se enfoca en la identi- ficación de aquellos factores estructurales que explican la pérdida de dinamismo económico de largo plazo en Colombia y, en particular, en el Valle del Cauca. Se examina la competitividad del Valle en relación con Colombia y con el resto del mundo. Se cuestiona la insistencia en una estrategia exportadora como dinamizadora del desarrollo económico. Se identifica que una gran parte de la población está excluida de los beneficios del desarrollo económico. Para construir un modelo de desarrollo que incluya a esta población se recomienda recuperar la senda de la industrialización, invertir en el capital humano (educación de alta calidad, salud, salubridad y nutrición, e invertir en infraestructura. La participación del Estado en estas inversiones sociales es necesaria para disminuir la desigualdad y aumentar el crecimiento económico.

  20. Espectroscopia del Cometa Halley

    Science.gov (United States)

    Naranjo, O.; Fuenmayor, F.; Ferrin, L.; Bulka, P.; Mendoza, C.

    1987-05-01

    Se reportan observaciones espectroscópicas del cometa Halley. Los espectros fueron tomados usando el espectrógrafo del telescopio reflector de 1 metro del Observatorio Nacional de Venezuela. Se utilizó óptica azul, con una red de difracción de 600 lineas/min, obteniéndose una dispersión de 74.2 A/mm y una resolución de 2.5 A, en el rango espectral de 3500 a 6500 A. Seis placas fueron tomadas con emulsión IIa-O y dos con IIa-D. Los tiempos de exposición fueron entre 10 y 150 minutos. El cometa se encontraba entre 0.70 y 1.04 UA del Sol, y entre 1.28 y 0.73 UA de la Tierra. Las emisiones más prominentes en el espectro, son las del CN, C2, y C3. Otras emisiones detectadas corresponden a CH, NH2 y Na. Los espectros muestran un fuerte continuo, indicando un contenido significativo de polvo. Se detectó mayor intensidad del contínuo, en la dirección anti solar, lo cual es evidencia de la cola de polvo.

  1. Inventario nacional del uso actual del agua

    OpenAIRE

    Oficina Nacional de Evaluación de Recursos Naturales

    1984-01-01

    Establece como se emplea el agua en el Perú, teniendo en cuenta el tipo de uso, consuntivo y no consuntivo, discriminando según sea el destino: agrícola, pecuario, poblacional,industrial, minero, energético y pesquero, así como su localización geográfica; ello con la finalidad de que sirva de información básica para la planificación del desarrollo.

  2. FRECUENCIAS ALELICAS Y GENOTIPICAS DEL GEN KAPPA CASEINA EN BOVINOS DE DOBLE PROPOSITO

    Directory of Open Access Journals (Sweden)

    Nohémi Gabriela Cortes López

    2012-01-01

    Full Text Available En este trabajo, las frecuencias alélicas (A y B del gen CAS se determinaron como criterio de selección en la calidad de la leche en el ganado bovino de doble propósito. Se tomaron muestras sanguíneas de 200 hembras bovinas y se colocaron en tubos que contenían EDTA. Se amplifico el marcador MB002 a partir de material genético extraído. Los RFLP se realizaron con la enzima de restricción Hinf I para el diagnóstico de los alelos A y B en CASκ. Las frecuencias genotípicas obtenidas correspondían a 0.34, 0.01 y 0.65 para los alelos AA, BB y AB, respectivamente. Las frecuencias alélicas fueron de 0.67 y 0.33 para los alelos A y B, respectivamente. Además, se registró una heterocigosidad promedio de 0.6481. La población es estudio no se encuentra en equilibrio Hardy Weinberg, el valor ji cuadrada fue de 2 = 14.8 con 2 grados de libertad (P < 0.005. Basado en la frecuencia alélica de CAS  B (0.34 observada en este estudio, el ganado de doble propósito puede ser una opción viable para aumentar la calidad de la leche si se utilizan sementales con el genotipo BB para el cruce. De esta manera, los alelos B asociados a la calidad de la leche pueden mejorarse en pocas generaciones.

  3. Forced extrusion for removal of impacted third molars close to the mandibular canal Extrusión forzada para extraer los terceros molares impactados cerca del canal mandibular

    Directory of Open Access Journals (Sweden)

    Dennis Flanagan DDS

    2012-03-01

    Full Text Available Impacted mandibular third molars can be located in close proximity to the mandibular canal. This creates a risk for the nerve or artery injury. These are contained in the canal. However, the impacted third molar can be moved coronally by orthodontic means, after removal of overlying bone, and safely extracted. The orthodontic intervention slowly moves the tooth apex away from the mandibular canal and reduces the potential for a neural injury. This method may be useful for older patients with root apices that approximate or are actually located in the mandibular canal. This technique needs further study. There is a theoretical potential for neural or arterial injury from physical contact of the tooth apex as it moves by or through the mandibular canal.Los terceros molares inferiores impactados pueden localizarse muy cerca del canal mandibular. Esto constituye un riesgo de lesión del nervio o la arteria, que se localizan dentro del canal. No obstante, el tercer molar impactado puede desplazarse en dirección coronal con ortodoncia, tras ostectomía del hueso suprayacente, y extraerse sin riesgos. La intervención ortodóncica desplaza lentamente el ápice del diente fuera del canal mandibular y reduce la posibilidad de lesión neural. Este método puede ser útil para pacientes de edad avanzada con ápices dentales que se aproximan o en realidad se localizan en el canal mandibular. La técnica necesita un estudio adicional. Hay la posibilidad teórica de lesión neural o arterial a partir del contacto físico del ápice del diente a medida que se desplaza a través del canal mandibular.

  4. Gerencia del cuidado-gerencia del servicio

    Directory of Open Access Journals (Sweden)

    Marta Palmet Jiménez

    2016-01-01

    Full Text Available La gerencia de este siglo debe estar plenamente identificada con la administración para planear, organizar, decidir y obtener resultados definidos, evaluados y alcanzados a través de las personas. Para poder gerenciar el cuidado se debe saber administrar. El objetivo de enfermería es cuidar; el objetivo de la gerencia es la conducción de la producción de bienes o servicios en las organizaciones. La gerencia del cuidado implica: motivación, creatividad, responsabilidad y ética por parte del cuidador y de quien cuida, claridad de actitud frente al ser y al qué hacer por parte del cuidador. Se puede concluir que la gerencia (administración, el cuidado (producto de calidad, el servicio (valor intangible, querer servir son un trinomio que deben ir de la mano de manera integrada para el logro de los objetivos propuestos por la organización de salud y de enfermería.

  5. Non-invasive neural stimulation

    Science.gov (United States)

    Tyler, William J.; Sanguinetti, Joseph L.; Fini, Maria; Hool, Nicholas

    2017-05-01

    Neurotechnologies for non-invasively interfacing with neural circuits have been evolving from those capable of sensing neural activity to those capable of restoring and enhancing human brain function. Generally referred to as non-invasive neural stimulation (NINS) methods, these neuromodulation approaches rely on electrical, magnetic, photonic, and acoustic or ultrasonic energy to influence nervous system activity, brain function, and behavior. Evidence that has been surmounting for decades shows that advanced neural engineering of NINS technologies will indeed transform the way humans treat diseases, interact with information, communicate, and learn. The physics underlying the ability of various NINS methods to modulate nervous system activity can be quite different from one another depending on the energy modality used as we briefly discuss. For members of commercial and defense industry sectors that have not traditionally engaged in neuroscience research and development, the science, engineering and technology required to advance NINS methods beyond the state-of-the-art presents tremendous opportunities. Within the past few years alone there have been large increases in global investments made by federal agencies, foundations, private investors and multinational corporations to develop advanced applications of NINS technologies. Driven by these efforts NINS methods and devices have recently been introduced to mass markets via the consumer electronics industry. Further, NINS continues to be explored in a growing number of defense applications focused on enhancing human dimensions. The present paper provides a brief introduction to the field of non-invasive neural stimulation by highlighting some of the more common methods in use or under current development today.

  6. Neural networks and applications tutorial

    Science.gov (United States)

    Guyon, I.

    1991-09-01

    The importance of neural networks has grown dramatically during this decade. While only a few years ago they were primarily of academic interest, now dozens of companies and many universities are investigating the potential use of these systems and products are beginning to appear. The idea of building a machine whose architecture is inspired by that of the brain has roots which go far back in history. Nowadays, technological advances of computers and the availability of custom integrated circuits, permit simulations of hundreds or even thousands of neurons. In conjunction, the growing interest in learning machines, non-linear dynamics and parallel computation spurred renewed attention in artificial neural networks. Many tentative applications have been proposed, including decision systems (associative memories, classifiers, data compressors and optimizers), or parametric models for signal processing purposes (system identification, automatic control, noise canceling, etc.). While they do not always outperform standard methods, neural network approaches are already used in some real world applications for pattern recognition and signal processing tasks. The tutorial is divided into six lectures, that where presented at the Third Graduate Summer Course on Computational Physics (September 3-7, 1990) on Parallel Architectures and Applications, organized by the European Physical Society: (1) Introduction: machine learning and biological computation. (2) Adaptive artificial neurons (perceptron, ADALINE, sigmoid units, etc.): learning rules and implementations. (3) Neural network systems: architectures, learning algorithms. (4) Applications: pattern recognition, signal processing, etc. (5) Elements of learning theory: how to build networks which generalize. (6) A case study: a neural network for on-line recognition of handwritten alphanumeric characters.

  7. Caracterización de la ovoposición del caracol Pomacea flagellata (Say, 1827 bajo condiciones experimentales

    Directory of Open Access Journals (Sweden)

    Alberto de Jesús-Navarrete

    2016-12-01

    Full Text Available Pomacea flagellata es un caracol conspicuo de zonas tropicales y subtropicales de América, que se ha consumido desde tiempos prehispánicos y actualmente es considerado sobreexplotado. Se realizó un experimento de cultivo de cuatro meses para determinar: la selección del substrato por la hembra, el tamaño de las huevas, el nivel del agua elegido para colocar la masa de huevos, el número de crías, y el tiempo de eclosión. Se utilizaron tres tinas de plástico que se llenaron con 100 L de agua, por duplicado y se colocaron tres sustratos: raíces de mangle, carrizo y tubo de PVC. Se registraron 57 huevas, 26 de ellas eclosionaron produciendo 5037 crías. Hubo más huevas en la “pared” de las tinas, donde se registraron 35 huevas, en raíces de mangle (18, en PVC 3 y en carrizo una hueva. Hubo diferencias significativas en la selección del sustrato, mientras que no se observaron diferencias significativas entre el número de huevas y las proporciones de sexos. La longitud promedio de la masa fue 32.99 ± 10.92, el ancho 16.44 ± 5.1 y grosor 8.08 ± 3.87 mm. La altura promedio de la puesta fue 15.66 ± 3.42 cm, con un tiempo medio de eclosión, de 13.30 ± 2.6 días, obteniéndose entre 94 a 301 crías por desove. Los caracoles utilizaron preferentemente las paredes de las tinas y es difícil determinar si no seleccionan sustrato para la puesta. El nivel del agua empleado es óptimo y permite que los organismos puedan colocar las masas de huevo, la producción de crías es adecuada y suficiente para iniciar programas de cultivo de producción de carne o de repoblación del medio natural.

  8. Parameterization Of Solar Radiation Using Neural Network

    International Nuclear Information System (INIS)

    Jiya, J. D.; Alfa, B.

    2002-01-01

    This paper presents a neural network technique for parameterization of global solar radiation. The available data from twenty-one stations is used for training the neural network and the data from other ten stations is used to validate the neural model. The neural network utilizes latitude, longitude, altitude, sunshine duration and period number to parameterize solar radiation values. The testing data was not used in the training to demonstrate the performance of the neural network in unknown stations to parameterize solar radiation. The results indicate a good agreement between the parameterized solar radiation values and actual measured values

  9. Dos nuevas Bignoniáceas del Valle del Magdalena

    Directory of Open Access Journals (Sweden)

    Dugand Armando

    1942-11-01

    Full Text Available Memora Romeroi: La especie aquí descrita pertenece a la sección Eumemora K. Schum. y es muy afín, según descripción, a M. caracasana K. Schum., de Venezuela, pero se distingue principalmente por tener racimos florales mucho más alargados, geminados y axilares, con 8, 12 a más flores opuestas, y por las brácteas infracalicinales de forma anchamente espatulada. Además, el cáliz y la corola son más cortos, particularmente el tubo basilar de esta última. EI raquis foliar y especialmente los peciolulos de M. Romeroi son diminutamente pubérulos, al menos durante mucho tiempo, y esta pubescencia menuda se presenta también en el raquis floral. / Tanaecium exitiosum: El doctor Rafael Mora, colector de esta muy interesante nueva especie, anota lo siguiente: "Arbusto que alcanza una altura de 2 metros; ocasionalmente crece más, arrollándose como bejuco a las otras plantas; las flores son de color blanco y de aspecto tubular alargado. La planta es abundante en las regiones secas de Barranca Bermeja y hay potreros que están completamente invadidos por ella".

  10. Determinantes del ingreso y del gasto corriente de los hogares

    OpenAIRE

    Muñoz C., Manuel

    2004-01-01

    Este ensayo de investigación empírica analiza los determinantes del ingreso y del gasto en los hogares colombianos. Utilizando un modelo del ciclo de vida con datos de la encuesta de hogares de 1994 y 1995, muestra que el comportamiento del ingreso está afectado principalmente por las características demográficas del hogar y los rasgos socio ocupacionales de sus miembros. El comportamiento del gasto está determinado ante todo por el ingreso y, en menor medida, por las características sociales...

  11. Las fluctuaciones del nivel del mar durante el Cuaternario

    OpenAIRE

    Pousa, Jorge Lorenzo; Isla, Federico Ignacio; Schnack, Enrique Jorge

    2002-01-01

    Los cambios del nivel del mar han ejercido una fuerte influencia en la evolución del planeta y en la historia de la humanidad. En una escala de tiempo geológico, las variaciones de los niveles oceánicos han dejado un registro ampliamente distribuido en la forma de depósitos sedimentarios. El descenso del nivel del mar durante la Ultima Glaciación, que alcanzó unos 120 metros hace 18.000 años, permitió la emergencia del estrecho de Bering y la migración humana desde Eurasia hacia América. Se e...

  12. La imagen del pase.

    Directory of Open Access Journals (Sweden)

    Hernando Bernal.

    1999-11-01

    Full Text Available A partir de un texto del poeta Octavio Paz llamado «La imagen», se busca proseguir la equivalencia entre las imágenes de la poesía y la función que ellas tienen para el poeta, y el fantasma fundamental y su función para el analizante que está en el momento del pase. Se parte de la idea de que la poesía busca entrar en el ser así como el psicoanálisis tiene como finalidad apuntar al corazón del ser del sujeto. Se hace entonces una distinción del concepto de «ser» para el psicoanálisis, haciendo alusión también al discurso de la filosofía. Esclarecido el sentido de lo que es el «ser» para el psicoanálisis, se aborda de lleno – entre otras cosas, relacionadas con la experiencia del pase específicamente- la equivalencia entre la definición que hace Octavio Paz de «La Imagen» y el momento del pase en el análisis de un sujeto, imagen que, al igual que el mito para la filosofía, las leyes para la ciencia y el matema para el psicoanálisis, se constituyen en los instrumentos con los que cada una de estas disciplinas horadan en lo real.

  13. Spike Neural Models Part II: Abstract Neural Models

    Directory of Open Access Journals (Sweden)

    Johnson, Melissa G.

    2018-02-01

    Full Text Available Neurons are complex cells that require a lot of time and resources to model completely. In spiking neural networks (SNN though, not all that complexity is required. Therefore simple, abstract models are often used. These models save time, use less computer resources, and are easier to understand. This tutorial presents two such models: Izhikevich's model, which is biologically realistic in the resulting spike trains but not in the parameters, and the Leaky Integrate and Fire (LIF model which is not biologically realistic but does quickly and easily integrate input to produce spikes. Izhikevich's model is based on Hodgkin-Huxley's model but simplified such that it uses only two differentiation equations and four parameters to produce various realistic spike patterns. LIF is based on a standard electrical circuit and contains one equation. Either of these two models, or any of the many other models in literature can be used in a SNN. Choosing a neural model is an important task that depends on the goal of the research and the resources available. Once a model is chosen, network decisions such as connectivity, delay, and sparseness, need to be made. Understanding neural models and how they are incorporated into the network is the first step in creating a SNN.

  14. del Estado Aragua

    Directory of Open Access Journals (Sweden)

    Joselys Cintia Zerpa

    2008-01-01

    Full Text Available Diagnostica la situación actual de los bienes que conforman al patrimonio histórico-cultural del Municipio Zamora, Estado Aragua, Venezuela. La Investigación es descriptiva y de campo, comprendió la elaboración de un inventario de los bienes inmuebles, festividades religiosas y manifestaciones artesanales del municipio. Se estudiaron la condición física y uso actual de estos bienes y los planes y proyectos existentes. Analizó el marco normativo que los rige. Se obtuvo la opinión de los representantes de organismos públicos relacionados con la actividad turística del Municipio, de los visitantes, cronistas e historiadores. Aportes: La mayoría de los bienes se encuentran en buen estado de conservación, Las manifestaciones culturales, festividades y la artesanía se desarrollan periódicamente pero no son aprovechadas turísticamente, Se determinó que existe un marco normativo para tales bienes y No existen propuestas actuales referentes a estos bienes. Se reflejó el interés de los sectores institucional y privado para la incorporación de estos bienes a la oferta turística del Municipio y del Estado

  15. APOSTILLAS ACERCA DEL POSTRABAJO

    Directory of Open Access Journals (Sweden)

    Arturo Torrecilla

    2000-01-01

    Full Text Available El más reciente debate en torno al postrabajo transforma la herencia de los dos ciclos que le precedieron desde los años setenta. El primero se correspondía con la crítica de la división social y técnica de labores informada por una filosofía de la alienación o bien por una rectificación de la arquitectónica marxista pero salvaguardando la promesa laborista del buen trabajo. El segundo ciclo hacía eco del rechazo a las cadenas de montaje fordistas y se abría al horizonte de la abolición del trabajo salarial, manteniendo sin embargo el abolengo del sujeto unitario de la historia. La presente escena asume una densidad mayor, producto del encuentro entre las nuevas tecnologías informacionales, las discusiones en el ámbito de la sociología y la antropología, de la tecnología y la ciencia, junto al dueto que inaugura el posmodernismo.

  16. Apostillas acerca del postrabajo

    Directory of Open Access Journals (Sweden)

    Arturo Torrecilla

    2000-04-01

    Full Text Available El más reciente debate en torno al postrabajo transforma la herencia de los dos ciclos que le precedieron desde los años setenta. El primero se correspondía con la crítica de la división social y técnica de labores informada por una filosofía de la alienación o bien por una rectificación de la arquitectónica marxista pero salvaguardando la promesa laborista del buen trabajo. El segundo ciclo hacía eco del rechazo a las cadenas de montaje fordistas y se abría al horizonte de la abolición del trabajo salarial, manteniendo sin embargo el abolengo del sujeto unitario de la historia. La presente escena asume una densidad mayor, producto del encuentro entre las nuevas tecnologías informacionales, las discusiones en el ámbito de la sociología y la antropología, de la tecnología y la ciencia, junto al dueto que inaugura el posmodernismo.

  17. La universidad del futuro

    Directory of Open Access Journals (Sweden)

    FERNANDO SANCÉN CONTRERAS

    2013-01-01

    Full Text Available El trabajo señala la necesidad de reconstruir la Universidad, dado el dinamismo que muestra la ciencia y la sociedad, pues trae consigo cambios sustanciales en la visión del mundo y en el aumento del poder del hombre sobre la naturaleza. Se analizan los supuestos epistemológicos de la universidad tradicional y se propone una nueva explicación del conocimiento humano, enfatizando el conocimiento científico. Postula una docencia fundada en las propiedades de la ciencia, cuyo método inductivo basado en los paradigmas vigentes: analítico, crítico, pragmático, ofrece una herramienta para la docencia, la investigación y la difusión de la cultura. Se propone una educación centrada en el sujeto que se hace a sí mismo (etopoiética y que insiste en el proceso de auto-creación del individuo y de la sociedad.

  18. Significado presente del CSIC

    Directory of Open Access Journals (Sweden)

    Garrido Gallardo, Miguel Angel

    2000-05-01

    Full Text Available Not available

    Este artículo, elaborado en 1999, ofrece una panorámica de la realidad del Consejo Superior de Investigaciones Científicas en la actualidad. Repasa su organización, su volumen de publicaciones, sus indicadores de productividad, su capacidad de obtener recursos y, en suma, su lugar en el conjunto del sistema español de Ciencia y Tecnología, considerado en sí mismo y en relación con la Universidad. Como conclusión del repaso de datos, se afirma que, aunque la fórmula del CSIC, como organismo nacional e interdisciplinario, no es la única posible, la organización del Estado de las Autonomías, así como la evaluación de los datos con que se cuenta, la hacen vivamente recomendable. No hay, pues, sino que seguir con su desarrollo.

  19. Dalt del tren

    Directory of Open Access Journals (Sweden)

    Jaume Subirana

    2001-11-01

    Full Text Available Ens consta que la saviesa popular hi toca més del que a aquest temps d’enquestes, telèfons mòbils i targetes de crèdit li ve de gust admetre, per això em fa gràcia, en veure la pausada però continuada intrusió de la cultura catalana a Internet, recordar les cançons de quan era petit: “Dalt del tren, tots anem-hi dalt del tren, hi ha lloc per tota la gent”, dèiem, i “El tren pinxo de Banyoles és el més bonic que hi ha, ple de llaunes i cassoles i barrets de capellà”. I resulta que per una vegada a la vida hem pujat, efectivament, dalt del tren que passava per l’estació de Catalunya i en cinc anys hem passat de gairebé res a prou pàgines amb un contingut, a més, apreciable i, sobretot, a un petit teixit de persones i institucions que han entès la importància de la revolució comunicativa que Internet representa i que hi teixeixen i projecten webs amb el convenciment dels conversos.

  20. Las carreras del futuro

    Directory of Open Access Journals (Sweden)

    Luis Piscoya Hermoza

    2011-07-01

    Full Text Available La primera década del siglo XXI ha estado signada por un énfasis en los estudiosde prospectiva, los mismos que, a partir de procesos de complejizacióny articulación de la sociedad planetaria como son la digitalización, el progresivodeterioro del medio ambiente, la necesidad del cambio de la matriz energéticay la globalización del mercado, han ensayado hipótesis para identificar lastendencias que se fortalecerán y profundizarán durante las próximas décadas.Desde el punto de vista metodológico, existen muchas maneras de clasificarlaspara conceptualizarlas y entenderlas mejor. Sin embargo, considerando lanaturaleza de esta edición nos proponemos enfocar directamente aquellas queestán estrechamente ligadas a la formación universitaria.Naturalmente, no pensamos que estamos ante tendencias inevitables en lamedida que epistemológicamente la creencia en leyes históricas deterministases insostenible y la práctica social nos muestra que la construcción del futuroes nuestra responsabilidad y siempre rebasa las mejores previsiones.

  1. Optical resonators and neural networks

    Science.gov (United States)

    Anderson, Dana Z.

    1986-08-01

    It may be possible to implement neural network models using continuous field optical architectures. These devices offer the inherent parallelism of propagating waves and an information density in principle dictated by the wavelength of light and the quality of the bulk optical elements. Few components are needed to construct a relatively large equivalent network. Various associative memories based on optical resonators have been demonstrated in the literature, a ring resonator design is discussed in detail here. Information is stored in a holographic medium and recalled through a competitive processes in the gain medium supplying energy to the ring rsonator. The resonator memory is the first realized example of a neural network function implemented with this kind of architecture.

  2. Neural Network for Sparse Reconstruction

    Directory of Open Access Journals (Sweden)

    Qingfa Li

    2014-01-01

    Full Text Available We construct a neural network based on smoothing approximation techniques and projected gradient method to solve a kind of sparse reconstruction problems. Neural network can be implemented by circuits and can be seen as an important method for solving optimization problems, especially large scale problems. Smoothing approximation is an efficient technique for solving nonsmooth optimization problems. We combine these two techniques to overcome the difficulties of the choices of the step size in discrete algorithms and the item in the set-valued map of differential inclusion. In theory, the proposed network can converge to the optimal solution set of the given problem. Furthermore, some numerical experiments show the effectiveness of the proposed network in this paper.

  3. IMNN: Information Maximizing Neural Networks

    Science.gov (United States)

    Charnock, Tom; Lavaux, Guilhem; Wandelt, Benjamin D.

    2018-04-01

    This software trains artificial neural networks to find non-linear functionals of data that maximize Fisher information: information maximizing neural networks (IMNNs). As compressing large data sets vastly simplifies both frequentist and Bayesian inference, important information may be inadvertently missed. Likelihood-free inference based on automatically derived IMNN summaries produces summaries that are good approximations to sufficient statistics. IMNNs are robustly capable of automatically finding optimal, non-linear summaries of the data even in cases where linear compression fails: inferring the variance of Gaussian signal in the presence of noise, inferring cosmological parameters from mock simulations of the Lyman-α forest in quasar spectra, and inferring frequency-domain parameters from LISA-like detections of gravitational waveforms. In this final case, the IMNN summary outperforms linear data compression by avoiding the introduction of spurious likelihood maxima.

  4. Genetic attack on neural cryptography.

    Science.gov (United States)

    Ruttor, Andreas; Kinzel, Wolfgang; Naeh, Rivka; Kanter, Ido

    2006-03-01

    Different scaling properties for the complexity of bidirectional synchronization and unidirectional learning are essential for the security of neural cryptography. Incrementing the synaptic depth of the networks increases the synchronization time only polynomially, but the success of the geometric attack is reduced exponentially and it clearly fails in the limit of infinite synaptic depth. This method is improved by adding a genetic algorithm, which selects the fittest neural networks. The probability of a successful genetic attack is calculated for different model parameters using numerical simulations. The results show that scaling laws observed in the case of other attacks hold for the improved algorithm, too. The number of networks needed for an effective attack grows exponentially with increasing synaptic depth. In addition, finite-size effects caused by Hebbian and anti-Hebbian learning are analyzed. These learning rules converge to the random walk rule if the synaptic depth is small compared to the square root of the system size.

  5. Neural Networks Methodology and Applications

    CERN Document Server

    Dreyfus, Gérard

    2005-01-01

    Neural networks represent a powerful data processing technique that has reached maturity and broad application. When clearly understood and appropriately used, they are a mandatory component in the toolbox of any engineer who wants make the best use of the available data, in order to build models, make predictions, mine data, recognize shapes or signals, etc. Ranging from theoretical foundations to real-life applications, this book is intended to provide engineers and researchers with clear methodologies for taking advantage of neural networks in industrial, financial or banking applications, many instances of which are presented in the book. For the benefit of readers wishing to gain deeper knowledge of the topics, the book features appendices that provide theoretical details for greater insight, and algorithmic details for efficient programming and implementation. The chapters have been written by experts ands seemlessly edited to present a coherent and comprehensive, yet not redundant, practically-oriented...

  6. Genetic attack on neural cryptography

    International Nuclear Information System (INIS)

    Ruttor, Andreas; Kinzel, Wolfgang; Naeh, Rivka; Kanter, Ido

    2006-01-01

    Different scaling properties for the complexity of bidirectional synchronization and unidirectional learning are essential for the security of neural cryptography. Incrementing the synaptic depth of the networks increases the synchronization time only polynomially, but the success of the geometric attack is reduced exponentially and it clearly fails in the limit of infinite synaptic depth. This method is improved by adding a genetic algorithm, which selects the fittest neural networks. The probability of a successful genetic attack is calculated for different model parameters using numerical simulations. The results show that scaling laws observed in the case of other attacks hold for the improved algorithm, too. The number of networks needed for an effective attack grows exponentially with increasing synaptic depth. In addition, finite-size effects caused by Hebbian and anti-Hebbian learning are analyzed. These learning rules converge to the random walk rule if the synaptic depth is small compared to the square root of the system size

  7. Genetic attack on neural cryptography

    Science.gov (United States)

    Ruttor, Andreas; Kinzel, Wolfgang; Naeh, Rivka; Kanter, Ido

    2006-03-01

    Different scaling properties for the complexity of bidirectional synchronization and unidirectional learning are essential for the security of neural cryptography. Incrementing the synaptic depth of the networks increases the synchronization time only polynomially, but the success of the geometric attack is reduced exponentially and it clearly fails in the limit of infinite synaptic depth. This method is improved by adding a genetic algorithm, which selects the fittest neural networks. The probability of a successful genetic attack is calculated for different model parameters using numerical simulations. The results show that scaling laws observed in the case of other attacks hold for the improved algorithm, too. The number of networks needed for an effective attack grows exponentially with increasing synaptic depth. In addition, finite-size effects caused by Hebbian and anti-Hebbian learning are analyzed. These learning rules converge to the random walk rule if the synaptic depth is small compared to the square root of the system size.

  8. Scheduling with artificial neural networks

    OpenAIRE

    Gürgün, Burçkaan

    1993-01-01

    Ankara : Department of Industrial Engineering and The Institute of Engineering and Sciences of Bilkent Univ., 1993. Thesis (Master's) -- Bilkent University, 1993. Includes bibliographical references leaves 59-65. Artificial Neural Networks (ANNs) attempt to emulate the massively parallel and distributed processing of the human brain. They are being examined for a variety of problems that have been very difficult to solve. The objective of this thesis is to review the curren...

  9. Handbook on neural information processing

    CERN Document Server

    Maggini, Marco; Jain, Lakhmi

    2013-01-01

    This handbook presents some of the most recent topics in neural information processing, covering both theoretical concepts and practical applications. The contributions include:                         Deep architectures                         Recurrent, recursive, and graph neural networks                         Cellular neural networks                         Bayesian networks                         Approximation capabilities of neural networks                         Semi-supervised learning                         Statistical relational learning                         Kernel methods for structured data                         Multiple classifier systems                         Self organisation and modal learning                         Applications to ...

  10. Deep Gate Recurrent Neural Network

    Science.gov (United States)

    2016-11-22

    and Fred Cummins. Learning to forget: Continual prediction with lstm . Neural computation, 12(10):2451–2471, 2000. Alex Graves. Generating sequences...DSGU) and Simple Gated Unit (SGU), which are structures for learning long-term dependencies. Compared to traditional Long Short-Term Memory ( LSTM ) and...Gated Recurrent Unit (GRU), both structures require fewer parameters and less computation time in sequence classification tasks. Unlike GRU and LSTM

  11. Adaptive Graph Convolutional Neural Networks

    OpenAIRE

    Li, Ruoyu; Wang, Sheng; Zhu, Feiyun; Huang, Junzhou

    2018-01-01

    Graph Convolutional Neural Networks (Graph CNNs) are generalizations of classical CNNs to handle graph data such as molecular data, point could and social networks. Current filters in graph CNNs are built for fixed and shared graph structure. However, for most real data, the graph structures varies in both size and connectivity. The paper proposes a generalized and flexible graph CNN taking data of arbitrary graph structure as input. In that way a task-driven adaptive graph is learned for eac...

  12. Adaptive Regularization of Neural Classifiers

    DEFF Research Database (Denmark)

    Andersen, Lars Nonboe; Larsen, Jan; Hansen, Lars Kai

    1997-01-01

    We present a regularization scheme which iteratively adapts the regularization parameters by minimizing the validation error. It is suggested to use the adaptive regularization scheme in conjunction with optimal brain damage pruning to optimize the architecture and to avoid overfitting. Furthermo......, we propose an improved neural classification architecture eliminating an inherent redundancy in the widely used SoftMax classification network. Numerical results demonstrate the viability of the method...

  13. EFECTO DEL ÁCIDO SALICÍLICO EN EL CRECIMIENTO DE LA RAÍZ Y BIOMASA TOTAL DE PLÁNTULAS DE TRIGO

    Directory of Open Access Journals (Sweden)

    Cesar J. Tucuch Haas

    2015-01-01

    Full Text Available Se reportan los resultados de dos experimentos independientes para evaluar el efecto del ácido salicílico (AS en plántulas de trigo (Triticum aestivum L.. Las plántulas de ambos experimentos se germinaron y crecieron en agrolita contenida en tubos de PVC y en condiciones de cielo abierto bajo un diseño experimental completamente al azar con 8 repeticiones por tratamiento, las plántulas se asperjaron durante 5 días con 1 y 0.1 µM de AS o agua como control. Diez días después fueron cosechadas y realizadas las mediciones. Los resultados señalan que el AS favoreció significativamente el peso fresco de la raíz, así como la altura y el peso fresco de la biomasa total, en comparación con el control. El mejor tratamiento para estimular el crecimiento de plántulas de trigo fue el de 1µM de AS.

  14. Componente Cultura del Agua del PMGRH: plan de trabajo

    OpenAIRE

    Autoridad Nacional del Agua; Proyecto de Modernización de la Gestión de Recursos Hídricos

    2012-01-01

    Describe el plan de trabajo del Componente Cultura del Agua del Proyecto de Modernización de la Gestión de Recursos Hídricos (PMGRH) en relacion a dos aspectos estructurales del proyecto: 1. Mejora de la capacidad de la Gestión Integrada de Recursos Hídricos (GIRH) a nivel nacional y 2. Fortalecimiento de las capacidades de GIRH en las cuencas.

  15. En busca del concepto de gerencia del cuidado

    Directory of Open Access Journals (Sweden)

    Ligia Teresa Mora-Delgado

    2005-12-01

    Full Text Available Este articulo, presenta los conceptos de gerencia del cuidado de enfermería, desarrollado por las enfermeras profesionales que laboran en le Empresa social del estado Hospital Universitario Erasmo Meoz de las Ciudad de Cúcuta, desde su desempeño en la asistencia, administración y docencia. Se pretende además precisar los elementos gerenciales, sociales, humanísticos y éticos que deben hacer parte del concepto de gerencia del cuidado.

  16. LA PERSISTENCIA DEL SUBALTERNO

    Directory of Open Access Journals (Sweden)

    John Beverley

    2002-01-01

    Full Text Available Este trabajo es el texto literal de una ponencia presentada en un panel sobre los estudios culturales latinoamericanos en el congreso de LASA en 2001 en Washington DC. Representa la posición desarrollada en el trabajo colectivo del llamado Grupo de Estudios Subalternos Latinoamericano, desde nuestra fundación en 1992 hasta la disolución del grupo en 2001, que sirve como pretexto introductorio para la ponencia. Los otros participantes en el panel eran Walter Mignolo, representando los estudios poscoloniales, Néstor García Canclini y John Kraniauskas, representando los estudios culturales, y Nelly Richard representando la llamada crítica cultural. El trabajo dialoga y debate con cada una de estas posiciones respectivamente desde el punto de vista específico de los estudios subalternos. Concluye con un llamado a una crítica del saber académico en sí.

  17. Acalasia. Controversias del tratamiento

    OpenAIRE

    Restrepo P, Antonio J; Rey T, Mario H; Garzón O, Martín A; Farfán Q, Yesid A; Molano V, Juan C; Marulanda, Juan C; Lizarazo, Jorge I

    2007-01-01

    La acalasia es un desorden motor del esófago caracterizado por pérdida de la peristalsis esofágica con falta en la relajación o relajación incompleta del esfínter esofágico inferior (EEI) (1). La causa exacta de este trastorno es desconocida. Los síntomas más comunes son disfagia, regurgitación, pérdida de peso y dolor torácico (2). La manometría esofágica es el principal método diagnóstico, mostrando aperistalsis del cuerpo esofágico con aumento de la presión, falta de relajación o relajació...

  18. Procedimiento Del Triple Fin

    Directory of Open Access Journals (Sweden)

    Oscar L. Bellido Aguilera

    2008-01-01

    Full Text Available Presenta un procedimiento novedoso basado en un método dialéctico - sistémico - integrador, que facilita la precisión de los fines u objetivos más generales de un proceso de desarrollo comunitario o de otros procesos de cambio deseados (un proyecto sociocultural, una investigación social, un proceso de mejoramiento organizacional, etc.. Su importancia radica en que los fines, según Marx, son una guía que rige como una ley la actuación del hombre y determinarlos es parte esencial del planeamiento del cambio. Se trata de un asunto aparentemente simple, sin embargo, en la práctica es mucho más problemático de lo que comúnmente se cree.

  19. Central neural pathways for thermoregulation

    Science.gov (United States)

    Morrison, Shaun F.; Nakamura, Kazuhiro

    2010-01-01

    Central neural circuits orchestrate a homeostatic repertoire to maintain body temperature during environmental temperature challenges and to alter body temperature during the inflammatory response. This review summarizes the functional organization of the neural pathways through which cutaneous thermal receptors alter thermoregulatory effectors: the cutaneous circulation for heat loss, the brown adipose tissue, skeletal muscle and heart for thermogenesis and species-dependent mechanisms (sweating, panting and saliva spreading) for evaporative heat loss. These effectors are regulated by parallel but distinct, effector-specific neural pathways that share a common peripheral thermal sensory input. The thermal afferent circuits include cutaneous thermal receptors, spinal dorsal horn neurons and lateral parabrachial nucleus neurons projecting to the preoptic area to influence warm-sensitive, inhibitory output neurons which control thermogenesis-promoting neurons in the dorsomedial hypothalamus that project to premotor neurons in the rostral ventromedial medulla, including the raphe pallidus, that descend to provide the excitation necessary to drive thermogenic thermal effectors. A distinct population of warm-sensitive preoptic neurons controls heat loss through an inhibitory input to raphe pallidus neurons controlling cutaneous vasoconstriction. PMID:21196160

  20. Adaptive competitive learning neural networks

    Directory of Open Access Journals (Sweden)

    Ahmed R. Abas

    2013-11-01

    Full Text Available In this paper, the adaptive competitive learning (ACL neural network algorithm is proposed. This neural network not only groups similar input feature vectors together but also determines the appropriate number of groups of these vectors. This algorithm uses a new proposed criterion referred to as the ACL criterion. This criterion evaluates different clustering structures produced by the ACL neural network for an input data set. Then, it selects the best clustering structure and the corresponding network architecture for this data set. The selected structure is composed of the minimum number of clusters that are compact and balanced in their sizes. The selected network architecture is efficient, in terms of its complexity, as it contains the minimum number of neurons. Synaptic weight vectors of these neurons represent well-separated, compact and balanced clusters in the input data set. The performance of the ACL algorithm is evaluated and compared with the performance of a recently proposed algorithm in the literature in clustering an input data set and determining its number of clusters. Results show that the ACL algorithm is more accurate and robust in both determining the number of clusters and allocating input feature vectors into these clusters than the other algorithm especially with data sets that are sparsely distributed.

  1. Neural mechanisms of social dominance

    Science.gov (United States)

    Watanabe, Noriya; Yamamoto, Miyuki

    2015-01-01

    In a group setting, individuals' perceptions of their own level of dominance or of the dominance level of others, and the ability to adequately control their behavior based on these perceptions are crucial for living within a social environment. Recent advances in neural imaging and molecular technology have enabled researchers to investigate the neural substrates that support the perception of social dominance and the formation of a social hierarchy in humans. At the systems' level, recent studies showed that dominance perception is represented in broad brain regions which include the amygdala, hippocampus, striatum, and various cortical networks such as the prefrontal, and parietal cortices. Additionally, neurotransmitter systems such as the dopaminergic and serotonergic systems, modulate and are modulated by the formation of the social hierarchy in a group. While these monoamine systems have a wide distribution and multiple functions, it was recently found that the Neuropeptide B/W contributes to the perception of dominance and is present in neurons that have a limited projection primarily to the amygdala. The present review discusses the specific roles of these neural regions and neurotransmitter systems in the perception of dominance and in hierarchy formation. PMID:26136644

  2. Neural mechanisms of social dominance

    Directory of Open Access Journals (Sweden)

    Noriya eWatanabe

    2015-06-01

    Full Text Available In a group setting, individuals’ perceptions of their own level of dominance or of the dominance level of others, and the ability to adequately control their behavior based on these perceptions are crucial for living within a social environment. Recent advances in neural imaging and molecular technology have enabled researchers to investigate the neural substrates that support the perception of social dominance and the formation of a social hierarchy in humans. At the systems’ level, recent studies showed that dominance perception is represented in broad brain regions which include the amygdala, hippocampus, striatum, and various cortical networks such as the prefrontal, and parietal cortices. Additionally, neurotransmitter systems such as the dopaminergic and serotonergic systems, modulate and are modulated by the formation of the social hierarchy in a group. While these monoamine systems have a wide distribution and multiple functions, it was recently found that the Neuropeptide B/W contributes to the perception of dominance and is present in neurons that have a limited projection primarily to the amygdala. The present review discusses the specific roles of these neural regions and neurotransmitter systems in the perception of dominance and in hierarchy formation.

  3. Neural Representations of Physics Concepts.

    Science.gov (United States)

    Mason, Robert A; Just, Marcel Adam

    2016-06-01

    We used functional MRI (fMRI) to assess neural representations of physics concepts (momentum, energy, etc.) in juniors, seniors, and graduate students majoring in physics or engineering. Our goal was to identify the underlying neural dimensions of these representations. Using factor analysis to reduce the number of dimensions of activation, we obtained four physics-related factors that were mapped to sets of voxels. The four factors were interpretable as causal motion visualization, periodicity, algebraic form, and energy flow. The individual concepts were identifiable from their fMRI signatures with a mean rank accuracy of .75 using a machine-learning (multivoxel) classifier. Furthermore, there was commonality in participants' neural representation of physics; a classifier trained on data from all but one participant identified the concepts in the left-out participant (mean accuracy = .71 across all nine participant samples). The findings indicate that abstract scientific concepts acquired in an educational setting evoke activation patterns that are identifiable and common, indicating that science education builds abstract knowledge using inherent, repurposed brain systems. © The Author(s) 2016.

  4. Photon spectrometry utilizing neural networks

    International Nuclear Information System (INIS)

    Silveira, R.; Benevides, C.; Lima, F.; Vilela, E.

    2015-01-01

    Having in mind the time spent on the uneventful work of characterization of the radiation beams used in a ionizing radiation metrology laboratory, the Metrology Service of the Centro Regional de Ciencias Nucleares do Nordeste - CRCN-NE verified the applicability of artificial intelligence (artificial neural networks) to perform the spectrometry in photon fields. For this, was developed a multilayer neural network, as an application for the classification of patterns in energy, associated with a thermoluminescent dosimetric system (TLD-700 and TLD-600). A set of dosimeters was initially exposed to various well known medium energies, between 40 keV and 1.2 MeV, coinciding with the beams determined by ISO 4037 standard, for the dose of 10 mSv in the quantity Hp(10), on a chest phantom (ISO slab phantom) with the purpose of generating a set of training data for the neural network. Subsequently, a new set of dosimeters irradiated in unknown energies was presented to the network with the purpose to test the method. The methodology used in this work was suitable for application in the classification of energy beams, having obtained 100% of the classification performed. (authors)

  5. Estudio experimental del comportamiento del hormigón confinado sometido a compresión

    OpenAIRE

    Aire Untiveros, Carlos Máximo

    2002-01-01

    La tesis presenta los resultados de un extenso estudio experimental de probetas cilíndricas de hormigón sometidas a confinamiento lateral cargadas axialmente. En el estudio se consideró el confinamiento activo y pasivo. El confinamiento activo consistió en aplicar una presión hidrostática en una célula triaxial y el confinamiento pasivo fue mediante tubos de acero rellenos de hormigón y probetas de hormigón zunchadas con polímeros reforzados con fibras (FRP) de carbono y vidrio. Se ensayaron ...

  6. Efecto del silicio y plaguicidas en la fertilidad del suelo y rendimiento del arroz

    OpenAIRE

    Furcal-Beriguete, Parménides; Herrera-Barrantes, Alejandra

    2013-01-01

    Efecto del silicio y plaguicidas en la fertilidad del suelo y rendimiento del arroz. El objetivo de este trabajo fue evaluar el efecto del silicio en la fertilidad del suelo, la incidencia de enfermedades y plagas insectiles, el rendimiento y la calidad de granos del cultivo de arroz. El estudio se realizó en La Vega, Florencia, San Carlos, Costa Rica entre mayo y octubre en los años 2010 y 2011, en el mismo lote con la variedad CR 4477. Se establecieron cinco tratamientos: silicio al suelo, ...

  7. Storia del pensiero matematico

    CERN Document Server

    Kline, Morris

    1999-01-01

    Costruita con l'intento di presentare le idee oltre ai protagonisti della matematica, questa storia ha il duplice pregio dell'esaustività e della chiarezza. Essa prevede infatti vari livelli di lettura: lo specialista vi trova una messe di dati, fonti e spunti di ricerca, mentre lo studente ha a disposizione un formidabile strumento di consultazione e sintesi. L'arco temporale coperto è vasto: dalla Mesopotamia a Euclide, da Fibonacci all'invenzione del calcolo infinitesimale, da Gauss a Poincare, con un'appendice dedicata agli sviluppi piu recenti scritta appositamente per la prima edizione italiana del 1991, nei «Manuali» Einaudi.

  8. La escritura del quechua

    OpenAIRE

    Authier, Martine du

    2015-01-01

    La mayor fantasía ha acompañado siempre la transcripción del quechua. El primer intento de sistematización fue el sistema de la Paz, en 1953. Sin embargo, no existe en el comercio un diccionario satisfactorio en lo que se refiere al quechua del Cusco y, prácticamente, nada se edita en quechua, fuera de algunos trabajos antropológicos bilingües. Bajo la égida de la UNESCO, la Academia Peruana de la Lengua Quechua, que tiene su sede en el Cusco, ha colaborado en un diccionario de doce de los tr...

  9. El lenguaje del cerebro

    Directory of Open Access Journals (Sweden)

    Antonio Ibáñez Molina

    2011-04-01

    Full Text Available La introducción de nuevas técnicas de análisis de ritmos EEG en estudio de la comprensión del lenguaje permite explorar esta habilidad humana desde una perspectiva de integración de grupos de redes neuronales. Los ritmos de disparo neuronal que generan estos grupos pueden conectarse por sincronía formando unidades funcionales transitorias distribuidas en diversas áreas del cerebro. En esta revisión comentamos algunos de estos ritmos y su relación con el lenguaje.

  10. Plasticidad del sistema nervioso

    Directory of Open Access Journals (Sweden)

    L. M. Garcia-Segura

    1976-06-01

    Full Text Available En este trabajo se revisan los conocimientos más recientes sobre el fenómeno de la plasticidad del sistéma nervioso, tanto a nivel morfológico como a nivel fisiológico y molecular. Se estudian los cambios morfólogicos y fisiológicos de las neuronas frente a la experiencia. Tambien se considera la adaptación molecular del sistéma nervioso a la información que recibe como la base de todo tipo de plasticidad.

  11. Las causas del desempleo

    OpenAIRE

    García Balbás, Salomé

    2014-01-01

    En este documento vamos a tratar de dar respuesta a la siguiente pregunta: ¿cuáles son las causas del desempleo? Para ello realizaremos un repaso de las principales teorías económicas del desempleo llegando a la conclusión de que existe una causa fundamental que lo genera: la rigidez de los salarios a la baja. Consideramos el desempleo como la existencia de un exceso de oferta en el mercado de trabajo y haremos alusión, únicamente, a la existencia de desempleo involuntario. La exposición de l...

  12. Ventana torácica en el tratamiento del empiema pleural crónico en el Hospital Nacional Cayetano Heredia, 1990-1998

    Directory of Open Access Journals (Sweden)

    Rosalba Lupe Maekawa Ykehara

    2002-07-01

    Full Text Available Objetivo: Describir los resultados de la ventana torácica en el manejo del empiema pleural. Pacientes y métodos: Estudio descriptivo, retrospectivo y transversal. Se incluyeron pacientes sometidos a ventana torácica (toracostomía entre 1990-1998, en el Hospital Nacional Cayetano Heredia. Se estudió el tratamiento quirúrgico (técnica, hallazgos y complicaciones, morbilidad y mortalidad. De los 59 casos estudiados 39 (66.1% fueron varones y 20 (33.9% mujeres. La edad promedio fue 30.9 ± 14 años. Resultados: Según la etiología, 55.93% tuvieron empiema pleural tuberculoso, 28.81% empiema post cirugía pulmonar, 11.86% empiema post neumónico y 3.39% empiema por traumatismo. El 95% de los casos fueron previamente drenados con tubo de toracostomía. El patrón radiológico predominante fue el hidroneumotórax (58%. El 64.4% fueron intervenidos bajo anestesia regional. El tiempo promedio operatorio fue de 57.3 ± 28 minutos. Los arcos costales resecados con más frecuencia fueron el 6°-7° (25%. El tiempo promedio de hospitalización fue 38.6 ± 26.9 días, el tiempo promedio postoperatorio fue 8.5 ± 8.3 días. De los pacientes que tuvieron un seguimiento mayor a 3 meses (33 pacientes, se pudo confirmar el cierre de la ventana torácica en 13 casos y reexpansión pulmonar en 21 casos. Conclusiones: La indicación principal fue la falta de respuesta al tubo de toracostomía de drenaje (40%. La etiología principal es el empiema pleural tuberculoso. Es un procedimiento ideal para pacientes severamente comprometidos e inmunosuprimidos. Las complicaciones postoperatorias fueron 11.86%. El porcentaje de reoperaciones fue de 3.4%. No se encontró mortalidad asociada al procedimiento. (Rev Med Hered 2002; 13: 90-98.

  13. Inventario del Archivo del conde de Bornos

    Directory of Open Access Journals (Sweden)

    Pedro Antonio Porras Arboledas

    1995-01-01

    Full Text Available Mi primer contacto con esta Casa se remonta a algunos años atrás, cuando me Mamó la atención un documento muy interesante, publicado a comienzos del presente siglo por el ilustre erudito ubetense don Alfredo Cazaban, por el que los Reyes Católicos hacían merced a su secretario y jefe de la artillería real durante la Guerra contra Granada, Francisco Ramírez de Madrid, personaje madrileño de origen cántabro, de una heredad en término de Jaén —el cortijo de Bornos— por sus grandes esfuerzos en la conquista de las plazas, hasta el momento inexpugnables, de Cambil y Alhabar. Posteriormente, al realizar un estudio sobre el régimen señorial en el Reino de Jaén, intenté localizar los archivos de las diferentes casas nobiliarias asentadas en esta provincia, gracias a lo cual pude saber que la documentación del Condado de Bornos se hallaba en Madrid, bien en la Biblioteca Nacional o en el Archivo Histórico, ya que el actual Conde, el Excmo. Sr. Don Ignacio Ramírez de Haro, así me lo comunicó en marzo de 1983.

  14. Amor y adicción: comparación de las características neurales y conductuales.

    OpenAIRE

    Fernando Maureira C.

    2009-01-01

    El amor es una experiencia placentera que se encuentra presente en todas las culturas y que posee una compleja base neurobiológica que la sustenta. El sistema neural del placer es fundamental para dicha experiencia y al contrario de lo que normalmente se piensa, el amor está ligado más con el sistema motivacional que con emociones. Los núcleos y los neurotransmisores que sintetizan la experiencia del amor son los mismos que sustentan la adicción a las drogas como la cocaína, las anfetaminas o...

  15. Study of the thermo-mechanical behavior of medium carbon microalloyed steel during hot forming process using an artificial neural network; Estudio del comportamiento termo-mecanico de un acero microaleado de medio carbono durante un proceso de conformado en caliente usando una red neuronal artificial

    Energy Technology Data Exchange (ETDEWEB)

    Alcelay, I.; Pena, E.; Al Omar, A.

    2016-10-01

    The thermo-mechanical behavior of medium carbon microalloyed steel has been analyzed by an Artificial Neural Network (ANN). The flow curves for training the ANN have been obtained from the hot compression tests, carried out over a temperature range varying from 900 to 1150 degree centigrade and at different true strain rates ranging from 10{sup -}4 to 10 s{sup -}1. It has been found that the ANN model developed in this study is capable to predict accurately and efficiently the flow behavior of the studied steel and there is a good agreement between the experimental results and the ANN results. To analyze the formability of the studied steel, processing maps have been constructed on the basis of the Dynamic Materials Model (DMM), using the ANN values of the flow stress. The study of maps reveals the different domains of the flow behavior of the studied steel and shows the great similarity between the experimental results and the theoretical results, so the use of the ANN can constitute an interesting alternative for design and study of hot forming processes. (Author)

  16. Competencia Desarrollo del Pensamiento Creativo

    OpenAIRE

    Rodríguez, Eric; Miceli, Francisco; Tiburcio, Georgina; Gómez, Orlando

    2012-01-01

    1. ¿Qué significa la competencia Desarrollo del Pensamiento Creativo? 2. ¿Por qué es relevante que adquiera la competencia Desarrollo del Pensamiento Creativo en mi formación? 3. ¿Cómo aprendo la competencia Desarrollo del Pensamiento Creativo? 4. ¿Cómo aplico la competencia Desarrollo del Pensamiento Creativo? 5. ¿Cómo puedo autoevaluar mi competencia (con miras a un constante crecimiento)?

  17. Tratamiento del enfisema intersticial pulmonar unilateral con ventilación monopulmonar contralateral: Presentación de 1 caso

    Directory of Open Access Journals (Sweden)

    María Victoria González Alonso

    1998-06-01

    Full Text Available Se presenta el caso de un recién nacido de 750 g de peso y 27 semanas de edad gestacional, que durante su evolución en la asistencia respiratoria mecánica, presentó enfisema intersticial pulmonar a tensión en el pulmón derecho, el cual producía desplazamiento mediastinal y pobre aereación del pulmón izquierdo. La subsecuente hipercapnia hizo fracasar todos los intentos de disminuir la presión inspiratoria en la vía aérea proximal y el enfisema intersticial fue empeorando. A los 6 días de vida se decide realizar intubación selectiva del bronquiotronco izquierdo y mantener al paciente con ventilación monopulmonar izquierda durante 36 horas. Al recolocar el tubo en la tráquea y reexpandirse el pulmón derecho, se observó una disminución notable del enfisema intersticial pulmonar y una mejoría gasométrica importante que permitió reducir la intensidad del apoyo ventilatorio. El paciente falleció posteriormente durante una enteritis necrosante.It is presented a case of a newborn of 750 g of weight and 27 weeks of gestational age that during his evolution in the mechanical respiratory assistance had a pulmonary interstitial emphysema on stress in the right lung, which produced mediastinal displacement and poor airing of the left lung. The subsequent hypercapsia made all the attempts to reduce the inspiratory pressure in the proximal air passage fail and therefore, the interstitial emphysema got worse. After the 6th day of life, it was decided to carry out selective intubation of the left bronchial trunk and to mantain the patient with left monopulmonary ventilation during 36 hours. On placing the tube into the trachea again, the right lung reexpanded and it was observed a remarkable decrease of the pulmonary interstitial emphysema and an important gasometric improvement that allowed to reduce that intensity of the ventilatory support. The patient died later due to a necrotizing enteritis.

  18. Neural plasticity of development and learning.

    Science.gov (United States)

    Galván, Adriana

    2010-06-01

    Development and learning are powerful agents of change across the lifespan that induce robust structural and functional plasticity in neural systems. An unresolved question in developmental cognitive neuroscience is whether development and learning share the same neural mechanisms associated with experience-related neural plasticity. In this article, I outline the conceptual and practical challenges of this question, review insights gleaned from adult studies, and describe recent strides toward examining this topic across development using neuroimaging methods. I suggest that development and learning are not two completely separate constructs and instead, that they exist on a continuum. While progressive and regressive changes are central to both, the behavioral consequences associated with these changes are closely tied to the existing neural architecture of maturity of the system. Eventually, a deeper, more mechanistic understanding of neural plasticity will shed light on behavioral changes across development and, more broadly, about the underlying neural basis of cognition. (c) 2010 Wiley-Liss, Inc.

  19. Neurosecurity: security and privacy for neural devices.

    Science.gov (United States)

    Denning, Tamara; Matsuoka, Yoky; Kohno, Tadayoshi

    2009-07-01

    An increasing number of neural implantable devices will become available in the near future due to advances in neural engineering. This discipline holds the potential to improve many patients' lives dramatically by offering improved-and in some cases entirely new-forms of rehabilitation for conditions ranging from missing limbs to degenerative cognitive diseases. The use of standard engineering practices, medical trials, and neuroethical evaluations during the design process can create systems that are safe and that follow ethical guidelines; unfortunately, none of these disciplines currently ensure that neural devices are robust against adversarial entities trying to exploit these devices to alter, block, or eavesdrop on neural signals. The authors define "neurosecurity"-a version of computer science security principles and methods applied to neural engineering-and discuss why neurosecurity should be a critical consideration in the design of future neural devices.

  20. The Neural Border: Induction, Specification and Maturation of the territory that generates Neural Crest cells.

    Science.gov (United States)

    Pla, Patrick; Monsoro-Burq, Anne H

    2018-05-28

    The neural crest is induced at the edge between the neural plate and the nonneural ectoderm, in an area called the neural (plate) border, during gastrulation and neurulation. In recent years, many studies have explored how this domain is patterned, and how the neural crest is induced within this territory, that also participates to the prospective dorsal neural tube, the dorsalmost nonneural ectoderm, as well as placode derivatives in the anterior area. This review highlights the tissue interactions, the cell-cell signaling and the molecular mechanisms involved in this dynamic spatiotemporal patterning, resulting in the induction of the premigratory neural crest. Collectively, these studies allow building a complex neural border and early neural crest gene regulatory network, mostly composed by transcriptional regulations but also, more recently, including novel signaling interactions. Copyright © 2018. Published by Elsevier Inc.

  1. Neurociencia y bilingüismo: efecto del primer idioma

    Directory of Open Access Journals (Sweden)

    Germary Díaz-Sánchez

    2013-08-01

    Full Text Available Desde la perspectiva neurobiológica, en este trabajo abordamos los efectos del idioma materno sobre el aprendizaje de una segunda lengua. Aunque existen investigaciones en diferentes países sobre este problema, pocas tratan el enfoque de la neurobiología y, menos aún, cuando se trata del español como idioma materno. Para la investigación se recopiló literatura descriptiva y experimental, con el fin de obtener los datos necesarios para alcanzar los objetivos; se realizó un metaanálisis cualitativo de los datos obtenidos, utilizando tablas de correlación. Los datos reflejaron que la adquisición de un segundo idioma siempre va a estar mediatizada por los esquemas ya establecidos del primer idioma y que existen aspectos neurobiológicos que subyacen a algunos mecanismos de interferencia y a la adquisición de un segundo lenguaje. Además, encontramos que, mientras más similares sean los idiomas, los mecanismos neurales subyacentes facilitan la transferencia del uno al otro.

  2. Ruptura del projecte parental i disposició dels preembrions

    OpenAIRE

    Farnós Amorós, Esther

    2010-01-01

    La tesi doctoral "Ruptura del projecte parental i disposició dels preembrions" analitza els efectes del consentiment a les tècniques de reproducció assistida prestat en el marc d'un projecte parental. La tesi ofereix una resposta als conflictes que enfronten exesposos o exconvivents en relació al destí dels preembrions sobrants d'un cicle de fecundació "in vitro" iniciat durant la relació. Aquests conflictes constitueixen un grup de casos al voltant del qual no hi ha solucions legislatives qu...

  3. La equinoterapia en las distintas alteraciones del desarrollo del menor.

    OpenAIRE

    Chamorro González, Mireya

    2015-01-01

    La equinoterapia consiste en la utilización del caballo como un método terapéutico para rehabilitar a personas con discapacidad. Esta terapia es considerada una gran alternativa para aumentar el autoestima de los que sufren algún tipo de discapacidad, también a través de esta terapia se mejora y fortalece el estado emocional, así del mismo modo ayuda a mejorar la manera de desenvolverse en su entorno social. Esta terapia se realiza a través de la trasmisión del calor corporal del caballo, del...

  4. Gestión del riesgo del cambio (segunda parte)

    OpenAIRE

    Zorrilla Salgador, Juan Pablo

    2004-01-01

    Segunda parte del artículo acerca del uso de futuros sobre el tipo de cambio. Esta continuación abarca estrategias, definiciones, metodología y explicaciones sobre todo lo relacionado con el Ratio de cobertura de los futuros y la aparición del riesgo base.Segunda parte del artículo acerca del uso de futuros sobre el tipo de cambio. Esta continuación abarca estrategias, definiciones, metodología y explicaciones sobre todo lo relacionado con el Ratio de cobertura de los futuros y la aparición d...

  5. Direct adaptive control using feedforward neural networks

    OpenAIRE

    Cajueiro, Daniel Oliveira; Hemerly, Elder Moreira

    2003-01-01

    ABSTRACT: This paper proposes a new scheme for direct neural adaptive control that works efficiently employing only one neural network, used for simultaneously identifying and controlling the plant. The idea behind this structure of adaptive control is to compensate the control input obtained by a conventional feedback controller. The neural network training process is carried out by using two different techniques: backpropagation and extended Kalman filter algorithm. Additionally, the conver...

  6. Introduction to Concepts in Artificial Neural Networks

    Science.gov (United States)

    Niebur, Dagmar

    1995-01-01

    This introduction to artificial neural networks summarizes some basic concepts of computational neuroscience and the resulting models of artificial neurons. The terminology of biological and artificial neurons, biological and machine learning and neural processing is introduced. The concepts of supervised and unsupervised learning are explained with examples from the power system area. Finally, a taxonomy of different types of neurons and different classes of artificial neural networks is presented.

  7. Mode Choice Modeling Using Artificial Neural Networks

    OpenAIRE

    Edara, Praveen Kumar

    2003-01-01

    Artificial intelligence techniques have produced excellent results in many diverse fields of engineering. Techniques such as neural networks and fuzzy systems have found their way into transportation engineering. In recent years, neural networks are being used instead of regression techniques for travel demand forecasting purposes. The basic reason lies in the fact that neural networks are able to capture complex relationships and learn from examples and also able to adapt when new data becom...

  8. Dynamic training algorithm for dynamic neural networks

    International Nuclear Information System (INIS)

    Tan, Y.; Van Cauwenberghe, A.; Liu, Z.

    1996-01-01

    The widely used backpropagation algorithm for training neural networks based on the gradient descent has a significant drawback of slow convergence. A Gauss-Newton method based recursive least squares (RLS) type algorithm with dynamic error backpropagation is presented to speed-up the learning procedure of neural networks with local recurrent terms. Finally, simulation examples concerning the applications of the RLS type algorithm to identification of nonlinear processes using a local recurrent neural network are also included in this paper

  9. Neural crest contributions to the lamprey head

    Science.gov (United States)

    McCauley, David W.; Bronner-Fraser, Marianne

    2003-01-01

    The neural crest is a vertebrate-specific cell population that contributes to the facial skeleton and other derivatives. We have performed focal DiI injection into the cranial neural tube of the developing lamprey in order to follow the migratory pathways of discrete groups of cells from origin to destination and to compare neural crest migratory pathways in a basal vertebrate to those of gnathostomes. The results show that the general pathways of cranial neural crest migration are conserved throughout the vertebrates, with cells migrating in streams analogous to the mandibular and hyoid streams. Caudal branchial neural crest cells migrate ventrally as a sheet of cells from the hindbrain and super-pharyngeal region of the neural tube and form a cylinder surrounding a core of mesoderm in each pharyngeal arch, similar to that seen in zebrafish and axolotl. In addition to these similarities, we also uncovered important differences. Migration into the presumptive caudal branchial arches of the lamprey involves both rostral and caudal movements of neural crest cells that have not been described in gnathostomes, suggesting that barriers that constrain rostrocaudal movement of cranial neural crest cells may have arisen after the agnathan/gnathostome split. Accordingly, neural crest cells from a single axial level contributed to multiple arches and there was extensive mixing between populations. There was no apparent filling of neural crest derivatives in a ventral-to-dorsal order, as has been observed in higher vertebrates, nor did we find evidence of a neural crest contribution to cranial sensory ganglia. These results suggest that migratory constraints and additional neural crest derivatives arose later in gnathostome evolution.

  10. Adaptive optimization and control using neural networks

    Energy Technology Data Exchange (ETDEWEB)

    Mead, W.C.; Brown, S.K.; Jones, R.D.; Bowling, P.S.; Barnes, C.W.

    1993-10-22

    Recent work has demonstrated the ability of neural-network-based controllers to optimize and control machines with complex, non-linear, relatively unknown control spaces. We present a brief overview of neural networks via a taxonomy illustrating some capabilities of different kinds of neural networks. We present some successful control examples, particularly the optimization and control of a small-angle negative ion source.

  11. The quest for a Quantum Neural Network

    OpenAIRE

    Schuld, M.; Sinayskiy, I.; Petruccione, F.

    2014-01-01

    With the overwhelming success in the field of quantum information in the last decades, the "quest" for a Quantum Neural Network (QNN) model began in order to combine quantum computing with the striking properties of neural computing. This article presents a systematic approach to QNN research, which so far consists of a conglomeration of ideas and proposals. It outlines the challenge of combining the nonlinear, dissipative dynamics of neural computing and the linear, unitary dynamics of quant...

  12. del's Proof

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 12; Issue 5. Gödel's Proof - Incompleteness Theorems. S M Srivastava. General Article Volume 12 Issue 5 May 2007 pp 71-84. Fulltext. Click here to view fulltext PDF. Permanent link: https://www.ias.ac.in/article/fulltext/reso/012/05/0071-0084. Keywords.

  13. Marketing Mix del Software.

    Directory of Open Access Journals (Sweden)

    Yudith del Carmen Rodríguez Pérez

    2006-03-01

    Por ello, en este trabajo se define el concepto de producto software, se caracteriza al mismo y se exponen sus atributos de calidad. Además, se aborda la mezcla de marketing del software necesaria y diferente a la de otros productos para que este triunfe en el mercado.

  14. Gerencia del servicio

    OpenAIRE

    Nancy Peña Acosta

    1992-01-01

    Estamos en la era de la pirámide invertida donde el cliente es primero por lo que es fundamental incentivar la calidad desde abajo; hacer que el trabajador defina su misión, sienta que es parte de la compañía para que la satisfacción del negocio realizado sea de todos.

  15. El Juego del Juego

    OpenAIRE

    Carvalho, Nazaré Cristina

    2012-01-01

    DUVIGNAUD, Jean. El Juego del Juego. Santafé de Bogotá, Colômbia: Fondo de Cultura Econômica, 1997.The game gameDUVIGNAUD, Jean. The Game Game. Santafé de Bogotá, Colombia: Fondo de Cultura Econômica, 1997

  16. El helor del cuerpo

    OpenAIRE

    Sánchez-Biosca, Vicente

    1992-01-01

    Ensayo sobre las formas clásicas y modernas de la metamorfosis. En esta figura mitológica se advierte de manera privilegiada la entrada del imaginario científico, biológico y genético en el dominio de las construcciones literarias y cinematográficas.

  17. Carta del Editor

    Directory of Open Access Journals (Sweden)

    Luis Eladio Proaño

    2014-12-01

    Full Text Available La publicación se centra en temas como: Procesos electorales en México e Italia, se analizan los procesos comunicacionales y sus efectos; las infiltraciones de las agencias de seguridad en la actividad periodística en Europa; la radio y la televisión pública en los EE.UU. Para conocer cómo la prensa enfrenta los problemas críticos entre países, esta el caso de Uruguay y Argentina (discrepancia por la planta de procesamiento de papel y la contaminación del Río de La Plata. Otro artículo refiere la difícil relación entre los medios de comunicación y el gobierno de Chávez en Venezuela. Se aborda el caso brasileño para entender el crecimiento de los Observatorios de Medios; otro sobre el crecimiento del "periodismo confidencial" en la web y la prensa gratuita. Se estudia el impacto de la telenovela "pasión de gavilanes". Para quienes interese la penetración del Internet está: "Usos y competencias del weblog en las corporaciones" más otro sobre la lucha sorda que mantienen los gigantes de la autopista de la información Google y Yahoo.

  18. Punctualizaciones del CERN

    CERN Multimedia

    2002-01-01

    "Viene de la pagina anterior. Puntualizaciones del CERN. La valoracion que me merece la aprobacion en el Consejo de Ministros el 24 de mayo de un acuerdo de colaboracion entre el MCYT y el CERN para el proyecto de neutrinos al Gran Sasso es positiva" (1 page).

  19. Software del sistema osteomioarticular

    Directory of Open Access Journals (Sweden)

    Dianelys León Medina

    2015-06-01

    Full Text Available Introducción: la aplicación en la enseñanza de las Tecnologías de la Informática y las Comunicaciones, es una de las líneas que ha trazado el sistema de salud cubano en estudiantes de las ciencias médicas. La anatomía es una de las ciencias que integra la disciplina de Morfofisiología y para facilitar su comprensión resulta necesario el empleo de recursos y estrategias, entre los que puede figurar un software educativo. Objetivo: diseñar un software sobre la anatomía del sistema osteomioarticular de cabeza y cuello para los estudiantes de primer año de la carrera de Estomatología de Pinar del Río. Material y método: se realizó un estudio cualitativo. Para obtener los resultados se utilizó el método materialista dialéctico. Para la dialéctica del desarrollo del proceso estudiado se utilizaron los métodos teóricos, empíricos, el estudio profundo del tema, tipo de plataforma a utilizar y criterios de los especialistas. Para su procesamiento se utilizaron técnicas estadísticas descriptivas e inferenciales no paramétricas. Resultados: debido a la necesidad de fortalecer en los estudiantes las habilidades en la utilización de las tecnologías de la informática y las comunicaciones, se elaboró el software de la anatomía del sistema osteomioarticular de cabeza y cuello "Aprendiendo anatomía" mediante imágenes, videos y textos. Conclusiones: el software constituye un aporte al proceso enseñanza aprendizaje, el cual facilita el trabajo independiente y autopreparación mediante la interactividad con el contenido, retroalimentación y evaluación utilizando medios de enseñanza modernos, lo cual tributa al modo de actuación del futuro egresado.

  20. Historia deldel = History of Padel

    Directory of Open Access Journals (Sweden)

    Bernardino Javier Sánchez-Alcaraz Martínez

    2013-10-01

    Full Text Available El presente trabajo resume la historia del deporte deldel. Existen dos versiones sobre el origen deldel. La primera versión relaciona los antecedentes deldel con los de otros deportes de raqueta como el tenis o el bádminton, siendo su origen común el jeu de la paume francés. Posteriormente, surgen variantes en Estados Unidos como el Paddle Tennis y el Platform Tennis, siendo versiones reducidas del tenis, pero con elementos muy comunes al pádel actual. La segunda versión, aprobada por la Federación Internacional de Pádel, afirma que este deporte nació en México, en 1969, a través del empresario Enrique Corcuera.--------------------------------------------------------------------This research summarizes the history of paddle sport. There are two versions about the origin of paddle. The first version relates the history of paddle with other racket sports like tennis or badminton, and its common origin of the Jeu de Paume French. Later, in in the United States, appear two sports called Paddle Tennis and Platform Tennis, which are reduced versions of tennis sport, but these have lot of common characteristics with paddle. The second version, approved by the International Padel Federation, said the sport was born in Mexico in 1969, through the businessman Enrique Corcuera.

  1. NeuroMEMS: Neural Probe Microtechnologies

    Directory of Open Access Journals (Sweden)

    Sam Musallam

    2008-10-01

    Full Text Available Neural probe technologies have already had a significant positive effect on our understanding of the brain by revealing the functioning of networks of biological neurons. Probes are implanted in different areas of the brain to record and/or stimulate specific sites in the brain. Neural probes are currently used in many clinical settings for diagnosis of brain diseases such as seizers, epilepsy, migraine, Alzheimer’s, and dementia. We find these devices assisting paralyzed patients by allowing them to operate computers or robots using their neural activity. In recent years, probe technologies were assisted by rapid advancements in microfabrication and microelectronic technologies and thus are enabling highly functional and robust neural probes which are opening new and exciting avenues in neural sciences and brain machine interfaces. With a wide variety of probes that have been designed, fabricated, and tested to date, this review aims to provide an overview of the advances and recent progress in the microfabrication techniques of neural probes. In addition, we aim to highlight the challenges faced in developing and implementing ultralong multi-site recording probes that are needed to monitor neural activity from deeper regions in the brain. Finally, we review techniques that can improve the biocompatibility of the neural probes to minimize the immune response and encourage neural growth around the electrodes for long term implantation studies.

  2. Fuzzy neural network theory and application

    CERN Document Server

    Liu, Puyin

    2004-01-01

    This book systematically synthesizes research achievements in the field of fuzzy neural networks in recent years. It also provides a comprehensive presentation of the developments in fuzzy neural networks, with regard to theory as well as their application to system modeling and image restoration. Special emphasis is placed on the fundamental concepts and architecture analysis of fuzzy neural networks. The book is unique in treating all kinds of fuzzy neural networks and their learning algorithms and universal approximations, and employing simulation examples which are carefully designed to he

  3. Practical neural network recipies in C++

    CERN Document Server

    Masters

    2014-01-01

    This text serves as a cookbook for neural network solutions to practical problems using C++. It will enable those with moderate programming experience to select a neural network model appropriate to solving a particular problem, and to produce a working program implementing that network. The book provides guidance along the entire problem-solving path, including designing the training set, preprocessing variables, training and validating the network, and evaluating its performance. Though the book is not intended as a general course in neural networks, no background in neural works is assum

  4. Boolean Factor Analysis by Attractor Neural Network

    Czech Academy of Sciences Publication Activity Database

    Frolov, A. A.; Húsek, Dušan; Muraviev, I. P.; Polyakov, P.Y.

    2007-01-01

    Roč. 18, č. 3 (2007), s. 698-707 ISSN 1045-9227 R&D Projects: GA AV ČR 1ET100300419; GA ČR GA201/05/0079 Institutional research plan: CEZ:AV0Z10300504 Keywords : recurrent neural network * Hopfield-like neural network * associative memory * unsupervised learning * neural network architecture * neural network application * statistics * Boolean factor analysis * dimensionality reduction * features clustering * concepts search * information retrieval Subject RIV: BB - Applied Statistics, Operational Research Impact factor: 2.769, year: 2007

  5. Determinantes del ingreso y del gasto corriente de los hogares

    Directory of Open Access Journals (Sweden)

    Muñoz C., Manuel

    2004-06-01

    Full Text Available Este ensayo de investigación empírica analiza los determinantes del ingreso y del gasto en los hogares colombianos. Utilizando un modelo del ciclo de vida con datos de la encuesta de hogares de 1994 y 1995, muestra que el comportamiento del ingreso está afectado principalmente por las características demográficas del hogar y los rasgos socio ocupacionales de sus miembros. El comportamiento del gasto está determinado ante todo por el ingreso y, en menor medida, por las características sociales del hogar y el gasto de otros hogares con características similares. También examina la influencia de la incertidumbre acerca de los ingresos en el gasto de los hogares para comprobar si estos actúan con motivos de precaución.

  6. Proceedings of the Organization of 1990 Meeting of International Neural Network Society Jointed with IEEE Held in Washington, DC on January 15 - 19, 1990. Volume 1. Theory Track Neural and cognitive Sciences Track

    Science.gov (United States)

    1990-11-30

    M. Romero £ UNIVERSIDAD AUTONOMA DEL ESTADO DE MEXICO UNIVERSIDAD AUTONOMA METROPOLITANA--IZTAPALAPA Laboratorio de Sistemas Complejos Ap. Postal 70...linear program. 1. Introduction. In a companion paper [2], we study two general neural network models for Linear Programming. Here, we introduce a... Sistemas Complejos Ap. Postal 70-499. C.P. 04510 Mexico, D.F. MEXICO Statistical Mechanics offers an interssting theoretical framework for the study of

  7. Estudio del CH interestelar

    Science.gov (United States)

    Olano, C.; Lemarchand, G.; Sanz, A. J.; Bava, J. A.

    El objetivo principal de este proyecto consiste en el estudio de la distribución y abundancia del CH en nubes interestelares a través de la observación de las líneas hiperfinas del CH en 3,3 GHz. El CH es una molécula de amplia distribución en el espacio interestelar y una de las pocas especies que han sido observadas tanto con técnicas de radio como ópticas. Desde el punto de vista tecnológico se ha desarrollado un cabezal de receptor que permitirá la realización de observaciones polarimétricas en la frecuencia de 3,3 GHz, con una temperatura del sistema de 60 K y un ancho de banda de 140 MHz, y que será instalado en el foco primario de la antena parabólica del IAR. El cabezal del receptor es capaz de detectar señales polarizadas, separando las componentes de polarización circular derecha e izquierda. Para tal fin el cabezal consta de dos ramas receptoras que amplificarán la señal y la trasladarán a una frecuencia más baja (frecuencia intermedia), permitiendo de esa forma un mejor transporte de la señal a la sala de control para su posterior procesamiento. El receptor además de tener características polarimétricas, podrá ser usado en el continuo y en la línea, utilizando las ventajas observacionales y de procesamiento de señal que actualmente posee el IAR.

  8. La pluridimensionalidad del rol del docente hospitalario

    Directory of Open Access Journals (Sweden)

    Marian Serradas Fonseca

    2015-07-01

    Full Text Available Este trabajo es el fruto de la observación y la investigación en la trayectoria personal y profesional de la autora dedicada a la educación de niños y niñas en situación de enfermedad u hospitalización. El objetivo de este ensayo es intentar definir de manera específica, el papel, tareas y competencias que el profesional del ámbito educativo tiene en la atención educativa hospitalaria; haciendo especial énfasis en la importancia de la formación de este profesional abogándose por una preparación que permita brindar una atención educativa de calidad a los niños y niñas en situación de enfermedad u hospitalizados.

  9. The LILARTI neural network system

    Energy Technology Data Exchange (ETDEWEB)

    Allen, J.D. Jr.; Schell, F.M.; Dodd, C.V.

    1992-10-01

    The material of this Technical Memorandum is intended to provide the reader with conceptual and technical background information on the LILARTI neural network system of detail sufficient to confer an understanding of the LILARTI method as it is presently allied and to facilitate application of the method to problems beyond the scope of this document. Of particular importance in this regard are the descriptive sections and the Appendices which include operating instructions, partial listings of program output and data files, and network construction information.

  10. Finite connectivity attractor neural networks

    International Nuclear Information System (INIS)

    Wemmenhove, B; Coolen, A C C

    2003-01-01

    We study a family of diluted attractor neural networks with a finite average number of (symmetric) connections per neuron. As in finite connectivity spin glasses, their equilibrium properties are described by order parameter functions, for which we derive an integral equation in replica symmetric approximation. A bifurcation analysis of this equation reveals the locations of the paramagnetic to recall and paramagnetic to spin-glass transition lines in the phase diagram. The line separating the retrieval phase from the spin-glass phase is calculated at zero temperature. All phase transitions are found to be continuous

  11. Neural Network Based Load Frequency Control for Restructuring ...

    African Journals Online (AJOL)

    Neural Network Based Load Frequency Control for Restructuring Power Industry. ... an artificial neural network (ANN) application of load frequency control (LFC) of a Multi-Area power system by using a neural network controller is presented.

  12. In-vitro differentiation induction of neural stem cells

    NARCIS (Netherlands)

    Balasubramaniyan, Veerakumar

    2006-01-01

    Neurale stamcellen maken de drie belangrijkste celtypes van ons zenuwstelsel aan. Veerakumar Balasubramaniyan onderzocht hoe neurale stamcellen kunnen worden aangezet tot het aanmaken van specifieke neurale celtypes. Met behulp van genetische technieken lukte het hem oligodendrocyten te verkrijgen:

  13. ABC del Ajedrez. I

    Directory of Open Access Journals (Sweden)

    Marisel Piñeiro Gomez

    2009-03-01

    Full Text Available La promoción del Ajedrez, su conocimiento y práctica por la población constituye uno de los programas de la Revolución, por tal motivo el presente trabajo está encaminado a proponer un material bibliográfico con variadas posiciones sobre el movimiento-captura de las piezas y los sistemas de notación para los masificadores de Ajedrez del municipio Pinar del Río. En esta investigación se utilizaron variados métodos: teóricos, empíricos y estadísticos, además, como método rector el dialéctico materialista. Constituye una novedad científica porque aporta un material bibliográfico que contiene: la composición,  disposición  e  identificación  del  tablero de  ajedrez;  identificación, colocación, movimiento y captura de las piezas de ajedrez; la promoción del Peón; el valor absoluto de las piezas; los sistemas de notación: descriptivo y algebraico. Se le incluyen más de trescientos gráficos, conceptos que son trabajados de lo simple a lo complejo de manera tal que el masificador de Ajedrez lo utilice en sus clases donde se viabilice el conocimiento gracias a las facilidades que le aporta el material; ofrece algoritmos que le guiarán a elaborar nuevas posiciones, los cuales son inexistentes para este propósito en otras bibliografías; su significación práctica radica en que proporciona, tanto al estudiantado como profesorado, ejercicios de ajedrez sencillos que les permitirá a los primeros para que les sirva en su comportamiento, y a los segundos utilizarlos en su auto preparación; el interés social se halla en que pueden ser utilizados por profesores, personal de apoyo a la docencia,  técnicos  del  INDER,  familiares  de  los  estudiantes  para  ayudarlos;  el interés educativo reside en que a través de esos ejercicios contribuimos al fortalecimiento de valores.

  14. Arco del milenio

    Directory of Open Access Journals (Sweden)

    Adell, Josep Mª

    2005-02-01

    the most significant stages in the erection of the Millennium Arch outside the Palacio de Congresos, venue for the 12th IBMAC.
    These pictures are divided into six chapters: Background, Components, Springline, Piers, Arch, Centring Erection and Removal, and Trimming.

    A lo largo de la historia, el Arco de fábrica ha sido el componente constructivo más característico de la Arquitectura y la Ingeniería desde que después de sus inicios etruscos en la época romana fuera desarrollado adelantándose con ello a la cultura helénica.
    El Arco, desde entonces, viene empleándose como una solución constructiva eficiente para cubrir espacios con materiales que no soportan tracciones. La originalidad técnica del Arco lo ha llevado a imponerse como símbolo de las hazañas bélicas como era el Arco de Triunfo.
    En el cambio de siglo y milenio en el que nos encontramos, un salto técnico fundamental se desvela en este Congreso, el Sistema de Albañilería Integral, que abre la posibilidad de ampliar el campo de aplicación de la albañilería con la incorporación del acero, a través de las perforaciones de las piezas, lográndose por fin armar en las tres direcciones del espacio cualquier muro de fábrica que se desee.
    El Arco del Milenio conmemoró el 12th IBMAC de Madrid, mostrando en él los avances técnicos que el Sistema de Albañilería Integral permite, al tratarse de un arco inclinado en el espacio y, por tanto, el primer arco de fábrica construido fuera de la vertical, mediante fábrica de Ladriflor aparejada a tizón, reforzada con barras y cercos.
    El Arco del Milenio, diseñado por J.M. Adell (Presidente del 12th IBMAC, parte de un cilindro de 14 m de diámetro, inclinado 30º sobre el terreno, y construido con fábrica de ladrillo de un pie de grueso, alternando una hilada de color amarillo de cada seis en rojo. El hueco deja un paso libre de 10 m de lado y 5,5 m de altura. La fábrica está armada regularmente por tendeles con cerchas cada

  15. Neural network modeling of emotion

    Science.gov (United States)

    Levine, Daniel S.

    2007-03-01

    This article reviews the history and development of computational neural network modeling of cognitive and behavioral processes that involve emotion. The exposition starts with models of classical conditioning dating from the early 1970s. Then it proceeds toward models of interactions between emotion and attention. Then models of emotional influences on decision making are reviewed, including some speculative (not and not yet simulated) models of the evolution of decision rules. Through the late 1980s, the neural networks developed to model emotional processes were mainly embodiments of significant functional principles motivated by psychological data. In the last two decades, network models of these processes have become much more detailed in their incorporation of known physiological properties of specific brain regions, while preserving many of the psychological principles from the earlier models. Most network models of emotional processes so far have dealt with positive and negative emotion in general, rather than specific emotions such as fear, joy, sadness, and anger. But a later section of this article reviews a few models relevant to specific emotions: one family of models of auditory fear conditioning in rats, and one model of induced pleasure enhancing creativity in humans. Then models of emotional disorders are reviewed. The article concludes with philosophical statements about the essential contributions of emotion to intelligent behavior and the importance of quantitative theories and models to the interdisciplinary enterprise of understanding the interactions of emotion, cognition, and behavior.

  16. Imaging Posture Veils Neural Signals

    Directory of Open Access Journals (Sweden)

    Robert T Thibault

    2016-10-01

    Full Text Available Whereas modern brain imaging often demands holding body positions incongruent with everyday life, posture governs both neural activity and cognitive performance. Humans commonly perform while upright; yet, many neuroimaging methodologies require participants to remain motionless and adhere to non-ecological comportments within a confined space. This inconsistency between ecological postures and imaging constraints undermines the transferability and generalizability of many a neuroimaging assay.Here we highlight the influence of posture on brain function and behavior. Specifically, we challenge the tacit assumption that brain processes and cognitive performance are comparable across a spectrum of positions. We provide an integrative synthesis regarding the increasingly prominent influence of imaging postures on autonomic function, mental capacity, sensory thresholds, and neural activity. Arguing that neuroimagers and cognitive scientists could benefit from considering the influence posture wields on both general functioning and brain activity, we examine existing imaging technologies and the potential of portable and versatile imaging devices (e.g., functional near infrared spectroscopy. Finally, we discuss ways that accounting for posture may help unveil the complex brain processes of everyday cognition.

  17. Learning in Artificial Neural Systems

    Science.gov (United States)

    Matheus, Christopher J.; Hohensee, William E.

    1987-01-01

    This paper presents an overview and analysis of learning in Artificial Neural Systems (ANS's). It begins with a general introduction to neural networks and connectionist approaches to information processing. The basis for learning in ANS's is then described, and compared with classical Machine learning. While similar in some ways, ANS learning deviates from tradition in its dependence on the modification of individual weights to bring about changes in a knowledge representation distributed across connections in a network. This unique form of learning is analyzed from two aspects: the selection of an appropriate network architecture for representing the problem, and the choice of a suitable learning rule capable of reproducing the desired function within the given network. The various network architectures are classified, and then identified with explicit restrictions on the types of functions they are capable of representing. The learning rules, i.e., algorithms that specify how the network weights are modified, are similarly taxonomized, and where possible, the limitations inherent to specific classes of rules are outlined.

  18. Neural dynamics in reconfigurable silicon.

    Science.gov (United States)

    Basu, A; Ramakrishnan, S; Petre, C; Koziol, S; Brink, S; Hasler, P E

    2010-10-01

    A neuromorphic analog chip is presented that is capable of implementing massively parallel neural computations while retaining the programmability of digital systems. We show measurements from neurons with Hopf bifurcations and integrate and fire neurons, excitatory and inhibitory synapses, passive dendrite cables, coupled spiking neurons, and central pattern generators implemented on the chip. This chip provides a platform for not only simulating detailed neuron dynamics but also uses the same to interface with actual cells in applications such as a dynamic clamp. There are 28 computational analog blocks (CAB), each consisting of ion channels with tunable parameters, synapses, winner-take-all elements, current sources, transconductance amplifiers, and capacitors. There are four other CABs which have programmable bias generators. The programmability is achieved using floating gate transistors with on-chip programming control. The switch matrix for interconnecting the components in CABs also consists of floating-gate transistors. Emphasis is placed on replicating the detailed dynamics of computational neural models. Massive computational area efficiency is obtained by using the reconfigurable interconnect as synaptic weights, resulting in more than 50 000 possible 9-b accurate synapses in 9 mm(2).

  19. Chimera States in Neural Oscillators

    Science.gov (United States)

    Bahar, Sonya; Glaze, Tera

    2014-03-01

    Chimera states have recently been explored both theoretically and experimentally, in various coupled nonlinear oscillators, ranging from phase-oscillator models to coupled chemical reactions. In a chimera state, both coherent and incoherent (or synchronized and desynchronized) states occur simultaneously in populations of identical oscillators. We investigate chimera behavior in a population of neural oscillators using the Huber-Braun model, a Hodgkin-Huxley-like model originally developed to characterize the temperature-dependent bursting behavior of mammalian cold receptors. One population of neurons is allowed to synchronize, with each neuron receiving input from all the others in its group (global within-group coupling). Subsequently, a second population of identical neurons is placed under an identical global within-group coupling, and the two populations are also coupled to each other (between-group coupling). For certain values of the coupling constants, the neurons in the two populations exhibit radically different synchronization behavior. We will discuss the range of chimera activity in the model, and discuss its implications for actual neural activity, such as unihemispheric sleep.

  20. Neural Networks. Diagnostic and inferential measurements; Reti neurali. Diagnostica e misure inferenziali

    Energy Technology Data Exchange (ETDEWEB)

    Bonavita, N. [Apc Group Leader, Abb Industria, Genua (Italy); Parisini, T. [Milan Politecnico, Milan (Italy). Dipt. di Elettronica e Informazione

    2000-09-01

    In this work, the use of neural approximating networks is described in the context of fault diagnosis of industrial plants with a particular emphasis to the technique of inferential measurements. The proposed methodology is related to the current literature emphasizing advantages and disadvantages of the analytical redundancy concept. The use of neural approximators for the generation of inferential measurement is described in the context of industrial distributed control systems. [Italian] In questo articolo viene descritta l'utilizzazione degli approssimatori neurali in problemi di diagnostica d'impianto con particolare riferimento alla tecnica delle misure inferenziali. Viene fornito un inquadramento della metodologia rispetto alla letteratura attuale mettendo in risalto vantaggi e svantaggi del concetto di ridondanza analitica. L'uso degli approssimatori neurali per la generazione di misure inferenziali e' illustrato in un contesto di sistemi di controllo distribuito di tipo industriale.

  1. Improved transformer protection using probabilistic neural network ...

    African Journals Online (AJOL)

    user

    secure and dependable protection for power transformers. Owing to its superior learning and generalization capabilities Artificial. Neural Network (ANN) can considerably enhance the scope of WI method. ANN approach is faster, robust and easier to implement than the conventional waveform approach. The use of neural ...

  2. Neural network signal understanding for instrumentation

    DEFF Research Database (Denmark)

    Pau, L. F.; Johansen, F. S.

    1990-01-01

    understanding research is surveyed, and the selected implementation and its performance in terms of correct classification rates and robustness to noise are described. Formal results on neural net training time and sensitivity to weights are given. A theory for neural control using functional link nets is given...

  3. A Chip for an Implantable Neural Stimulator

    DEFF Research Database (Denmark)

    Gudnason, Gunnar; Bruun, Erik; Haugland, Morten

    2000-01-01

    This paper describes a chip for a multichannel neural stimulator for functional electrical stimulation (FES). The purpose of FES is to restore muscular control in disabled patients. The chip performs all the signal processing required in an implanted neural stimulator. The power and digital data...

  4. Hidden neural networks: application to speech recognition

    DEFF Research Database (Denmark)

    Riis, Søren Kamaric

    1998-01-01

    We evaluate the hidden neural network HMM/NN hybrid on two speech recognition benchmark tasks; (1) task independent isolated word recognition on the Phonebook database, and (2) recognition of broad phoneme classes in continuous speech from the TIMIT database. It is shown how hidden neural networks...

  5. Neural Network Classifier Based on Growing Hyperspheres

    Czech Academy of Sciences Publication Activity Database

    Jiřina Jr., Marcel; Jiřina, Marcel

    2000-01-01

    Roč. 10, č. 3 (2000), s. 417-428 ISSN 1210-0552. [Neural Network World 2000. Prague, 09.07.2000-12.07.2000] Grant - others:MŠMT ČR(CZ) VS96047; MPO(CZ) RP-4210 Institutional research plan: AV0Z1030915 Keywords : neural network * classifier * hyperspheres * big -dimensional data Subject RIV: BA - General Mathematics

  6. A high-speed analog neural processor

    NARCIS (Netherlands)

    Masa, P.; Masa, Peter; Hoen, Klaas; Hoen, Klaas; Wallinga, Hans

    1994-01-01

    Targeted at high-energy physics research applications, our special-purpose analog neural processor can classify up to 70 dimensional vectors within 50 nanoseconds. The decision-making process of the implemented feedforward neural network enables this type of computation to tolerate weight

  7. Neurophysiology and neural engineering: a review.

    Science.gov (United States)

    Prochazka, Arthur

    2017-08-01

    Neurophysiology is the branch of physiology concerned with understanding the function of neural systems. Neural engineering (also known as neuroengineering) is a discipline within biomedical engineering that uses engineering techniques to understand, repair, replace, enhance, or otherwise exploit the properties and functions of neural systems. In most cases neural engineering involves the development of an interface between electronic devices and living neural tissue. This review describes the origins of neural engineering, the explosive development of methods and devices commencing in the late 1950s, and the present-day devices that have resulted. The barriers to interfacing electronic devices with living neural tissues are many and varied, and consequently there have been numerous stops and starts along the way. Representative examples are discussed. None of this could have happened without a basic understanding of the relevant neurophysiology. I also consider examples of how neural engineering is repaying the debt to basic neurophysiology with new knowledge and insight. Copyright © 2017 the American Physiological Society.

  8. Neural Networks for Non-linear Control

    DEFF Research Database (Denmark)

    Sørensen, O.

    1994-01-01

    This paper describes how a neural network, structured as a Multi Layer Perceptron, is trained to predict, simulate and control a non-linear process.......This paper describes how a neural network, structured as a Multi Layer Perceptron, is trained to predict, simulate and control a non-linear process....

  9. Interpretable neural networks with BP-SOM

    NARCIS (Netherlands)

    Weijters, A.J.M.M.; Bosch, van den A.P.J.; Pobil, del A.P.; Mira, J.; Ali, M.

    1998-01-01

    Artificial Neural Networks (ANNS) are used successfully in industry and commerce. This is not surprising since neural networks are especially competitive for complex tasks for which insufficient domain-specific knowledge is available. However, interpretation of models induced by ANNS is often

  10. Deciphering the Cognitive and Neural Mechanisms Underlying ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Deciphering the Cognitive and Neural Mechanisms Underlying Auditory Learning. This project seeks to understand the brain mechanisms necessary for people to learn to perceive sounds. Neural circuits and learning. The research team will test people with and without musical training to evaluate their capacity to learn ...

  11. The neural network approach to parton fitting

    International Nuclear Information System (INIS)

    Rojo, Joan; Latorre, Jose I.; Del Debbio, Luigi; Forte, Stefano; Piccione, Andrea

    2005-01-01

    We introduce the neural network approach to global fits of parton distribution functions. First we review previous work on unbiased parametrizations of deep-inelastic structure functions with faithful estimation of their uncertainties, and then we summarize the current status of neural network parton distribution fits

  12. NEURAL METHODS FOR THE FINANCIAL PREDICTION

    OpenAIRE

    Jerzy Balicki; Piotr Dryja; Waldemar Korłub; Piotr Przybyłek; Maciej Tyszka; Marcin Zadroga; Marcin Zakidalski

    2016-01-01

    Artificial neural networks can be used to predict share investment on the stock market, assess the reliability of credit client or predicting banking crises. Moreover, this paper discusses the principles of cooperation neural network algorithms with evolutionary method, and support vector machines. In addition, a reference is made to other methods of artificial intelligence, which are used in finance prediction.

  13. NEURAL METHODS FOR THE FINANCIAL PREDICTION

    Directory of Open Access Journals (Sweden)

    Jerzy Balicki

    2016-06-01

    Full Text Available Artificial neural networks can be used to predict share investment on the stock market, assess the reliability of credit client or predicting banking crises. Moreover, this paper discusses the principles of cooperation neural network algorithms with evolutionary method, and support vector machines. In addition, a reference is made to other methods of artificial intelligence, which are used in finance prediction.

  14. Neural Network to Solve Concave Games

    OpenAIRE

    Liu, Zixin; Wang, Nengfa

    2014-01-01

    The issue on neural network method to solve concave games is concerned. Combined with variational inequality, Ky Fan inequality, and projection equation, concave games are transformed into a neural network model. On the basis of the Lyapunov stable theory, some stability results are also given. Finally, two classic games’ simulation results are given to illustrate the theoretical results.

  15. Neural Network Algorithm for Particle Loading

    International Nuclear Information System (INIS)

    Lewandowski, J.L.V.

    2003-01-01

    An artificial neural network algorithm for continuous minimization is developed and applied to the case of numerical particle loading. It is shown that higher-order moments of the probability distribution function can be efficiently renormalized using this technique. A general neural network for the renormalization of an arbitrary number of moments is given

  16. Neural constructivism or self-organization?

    NARCIS (Netherlands)

    van der Maas, H.L.J.; Molenaar, P.C.M.

    2000-01-01

    Comments on the article by S. R. Quartz et al (see record 1998-00749-001) which discussed the constructivist perspective of interaction between cognition and neural processes during development and consequences for theories of learning. Three arguments are given to show that neural constructivism

  17. Memory in Neural Networks and Glasses

    NARCIS (Netherlands)

    Heerema, M.

    2000-01-01

    The thesis tries and models a neural network in a way which, at essential points, is biologically realistic. In a biological context, the changes of the synapses of the neural network are most often described by what is called `Hebb's learning rule'. On careful analysis it is, in fact, nothing but a

  18. Windowed active sampling for reliable neural learning

    NARCIS (Netherlands)

    Barakova, E.I; Spaanenburg, L

    The composition of the example set has a major impact on the quality of neural learning. The popular approach is focused on extensive pre-processing to bridge the representation gap between process measurement and neural presentation. In contrast, windowed active sampling attempts to solve these

  19. Neural Control of the Immune System

    Science.gov (United States)

    Sundman, Eva; Olofsson, Peder S.

    2014-01-01

    Neural reflexes support homeostasis by modulating the function of organ systems. Recent advances in neuroscience and immunology have revealed that neural reflexes also regulate the immune system. Activation of the vagus nerve modulates leukocyte cytokine production and alleviates experimental shock and autoimmune disease, and recent data have…

  20. Determinantes del trabajo infantil y la escolaridad: el caso del Valle del Cauca en Colombia

    Directory of Open Access Journals (Sweden)

    Sebastián Urueña Abadía

    2009-10-01

    Full Text Available Colombia, al igual que la mayoría de países latinoamericanos, consciente de las repercusiones sociales y económicas negativas del trabajo infantil, se ha comprometido en la lucha por la erradicación de este fenómeno. Prueba de ello es la ratificación por parte del gobierno colombiano en el año 2007, del Convenio 182 de la OIT sobre la Prohibición de las Peores Formas de Trabajo Infantil y la Acción Inmediata para su Eliminación. En el plano regional, como parte del Plan de Desarrollo del Departamento del Valle del Cauca 2008-2011, se está implementando actualmente una estrategia territorial de erradicación del trabajo infantil en sus 42 municipios. Considerando este panorama, este trabajo indaga cuáles son los determinantes del trabajo infantil y la escolaridad en el departamento del Valle a partir de los datos de la Encuesta Nacional de Calidad de Vida del año 2003. Para el análisis se emplea un modelo econométrico Probit Bivariado, que permite el estudio conjunto e interrelacionado de decisiones diferentes, en este caso la asistencia escolar y el trabajo.

  1. Diagnóstico precoz del cáncer gástrico estrategias de prevención secundaria y dificultades del diagnóstico de lesiones precoces

    Directory of Open Access Journals (Sweden)

    Dr. B. Alfonso Calvo

    2011-07-01

    Full Text Available El cáncer gástrico persiste como un problema importante de salud pública a nivel mundial. En Chile es la primera causa de mortalidad por tumores malignos. En 1962 se definió el concepto de cáncer gástrico precoz, pasando a ser una enfermedad curable si era pesquisado en estas etapas, con sobrevida de 90% o más a 5 años. La estrategia implementada en Japón para detectarlo en etapas precoces fue a través de estudios masivos en población presuntamente asintomática. Esta estrategia ha sido exitosa en los cánceres detectados en etapa precoz pero con alto costo y bajo rendimiento, no aplicable en países en desarrollo con alto riesgo. La endoscopía ha desplazado a la radiología en el estudio de las enfermedades del tubo digestivo. Otra forma de enfrentar el problema en países en desarrollo con alto riesgo, es focalizar la endoscopía en sujetos sintomáticos. Desde 1996 se desarrolla un programa de detección de cáncer gástrico mediante esta última estrategia en la comuna de La Florida, Región Metropolitana. Se presenta un análisis preliminar de 12 años de este programa y se comentan las dificultades para un diagnóstico precoz.

  2. A new perspective on behavioral inconsistency and neural noise in aging: Compensatory speeding of neural communication

    Directory of Open Access Journals (Sweden)

    S. Lee Hong

    2012-09-01

    Full Text Available This paper seeks to present a new perspective on the aging brain. Here, we make connections between two key phenomena of brain aging: 1 increased neural noise or random background activity; and 2 slowing of brain activity. Our perspective proposes the possibility that the slowing of neural processing due to decreasing nerve conduction velocities leads to a compensatory speeding of neuron firing rates. These increased firing rates lead to a broader distribution of power in the frequency spectrum of neural oscillations, which we propose, can just as easily be interpreted as neural noise. Compensatory speeding of neural activity, as we present, is constrained by the: A availability of metabolic energy sources; and B competition for frequency bandwidth needed for neural communication. We propose that these constraints lead to the eventual inability to compensate for age-related declines in neural function that are manifested clinically as deficits in cognition, affect, and motor behavior.

  3. En defensa del indigenismo

    Directory of Open Access Journals (Sweden)

    Miguel Ángel Huamán

    2011-05-01

    Full Text Available El indigenismo como movimiento literario, cultural, ideológico y políticoconstituye un hito, una referencia obligada de nuestra tradición culturaly literaria nacional. Su debate no se reduce ni limita a las primerasdécadas del siglo XX, etapa privilegiada en forma recurrente en los estudiosiniciales sobre esta corriente. Podemos afirmar, sin temor a equivocarnos,que no hay momento ni periodo, más o menos visible, en elque no se haya evaluado en forma crítica este acontecimiento, el mismoque ha resurgido con otras denominaciones o referencias (regionalismo,andinismo, mariateguismo, humalismo, etc., a lo largo de nuestro procesohistórico, pero imbuidas de la perspectiva inicial. El propósito deeste artículo es hacer una defensa del indigenismo contestando algunasposiciones contrarias como la de Mirko Lauer.

  4. RESPONSABILIDAD DEL ODONTOPEDIATRA

    OpenAIRE

    Guillen B., Celso

    2014-01-01

    La Responsabilidad de la atención del niño, requiere de una formación y preparación universitaria de la Segunda Especialidad en Odontopediatría para manejar organismos en proceso de crecimiento somático y psicológico. Es por eso que con el proceso de la ciencia se ha comprendido la importancia de la atención del niño desde que nace. Es así que se ha creado sistemas integrales de atención odontopediátrica durante los primeros años de vida, debido a la alta vulnerabilidad de contraer las enferm...

  5. Responsabilidad Constitucional del Gobierno

    Directory of Open Access Journals (Sweden)

    Francisco Zúñiga Urbina

    2006-01-01

    Full Text Available El artículo analiza la responsabilidad constitucional del Gobierno y sostiene que es jurídico-política, de lejano cuño penal y administrativo, y el procedimiento empleado para hacerla efectiva es la acusación en juicio político, que es un típico caso de "justicia política". A la responsabilidad constitucional se suman las responsabilidades civil y penal de Derecho Público del Presidente de la República y sus ministrosThis paper analyses constitutional responsibility of the government and sustains that it is political and juridical, of distant penal and administrative inspiration, and that the procedure used for persecution is impeachment in political trials, demonstrating a typical case of "political justice." Added to the constitutional responsibility of the government are the civil and penal responsibilities of the President and minister's public law

  6. Infecciones del tracto urinario

    Directory of Open Access Journals (Sweden)

    K. Andrés Wurgaft, Dr.

    2010-07-01

    Full Text Available La infección del tracto urinario (ITU, con sus múltiples presentaciones clínicas, está entre las enfermedades infecciosas más frecuentes, tanto en pacientes ambulatorios como hospitalizados. El uso del examen de orina completa y de urocultivo debe ser racional. La bacteriuria asintomática no debe ser buscada ni tratada, en parte porque esto favorece el desarrollo de bacterias resistentes a antibióticos. Distintos cuadros clínicos requieren de distintas duraciones de terapia antibiótica, y tanto el exceso de días de tratamiento como su falta deben evitarse. Se requiere investigación en la búsqueda de estrategias más efectivas para prevenir las ITU recurrentes y en el desarrollo de nuevos antibióticos orales para las ITU resistentes.

  7. Las cruces del olvido

    Directory of Open Access Journals (Sweden)

    Carla Fernandes

    2012-08-01

    Full Text Available Les tragiques événements du « mars paraguayen » ont signifié la disparition de l’espoir en la transition démocratique dans laquelle le pays s’était engagé depuis presque une dizaine d’années. Renée Ferrer, poète, dramaturge, auteur de plusieurs recueils de contes et de deux romans, consigne alors le témoignage poétique de ce drame national dans le recueil Las cruces del olvido (2001. Elle a auparavant publié d’autres textes qui peuvent rentrer dans la catégorie de la poésie sociale : c’est le cas en particulier de Viaje a destiempo (1989 dédié aux victimes de la dictature. Las cruces del olvido, dès son paratexte, insiste sur la fonction de témoignage que l’auteur souhaite assigner à ses vers et sur le rôle que ceux-ci peuvent jouer dans la transmission d’une mémoire collective. La voix d’un jeune disparu de ce « mars paraguayen », le dédoublement qu’il subit et travers lequel il évoque son entrée dans la mort et son absence du monde des vivants, rendent possible l’écriture de cette expérience de l’indicible qu’est la disparition.Los trágicos acontecimientos del «marzo paraguayo» significaron la desaparición de la esperanza en la transición democrática que el país está viviendo desde unos diez años. Renée Ferrer, poeta, dramaturga, autora de varios libros de cuentos y de dos novelas, escribe entonces el testimonio poético de ese drama nacional en su poemario Las cruces del olvido (2001. Ya había publicado antes textos que se pueden considerar como poesía social: es el caso de Viaje a destiempo (1989 dedicado a las víctimas de la dictadura. Desde el texto apertural, Las cruces del olvido potencia la función de testimonio que la autora desea conceder a sus versos y el papel que éstos pueden desempeñar en la transmisión de una memoria colectiva. La voz de un joven desaparecido del «marzo paraguayo», el desdoblamiento que sufre y a través del cual evoca su entrada en la

  8. Carta del editor

    Directory of Open Access Journals (Sweden)

    José Sánchez Gutiérrez

    2018-01-01

    Full Text Available La comunicación científica en México vive enormes retos ante la carrera de adaptar sus formas de comunicación a las nuevas tecnologías. No es tarea fácil convencerse de abandonar el papel y la imprenta para apostar por el código abierto. Sin embargo, esto es apremiante debido al retraso que se lleva en comparación con otras regiones.  Un reto muy evidente ha sido comprender el acceso abierto, reconociendo que este permite mayor visibilidad a la ciencia y que ayuda a evitar el plagio.  Razón por la que nos alegra que a partir del número 37, Mercados y Negocios cuenta con el ISSN electrónico, además del impreso

  9. Carta del Editor

    OpenAIRE

    Luis Eladio Proaño

    2015-01-01

    Henos aquí con un nuevo número de RIESED. Después de casi un año de ver la luz, y como lo anticipábamos en la carta del editor que acompañaba al número fundacional, hacer una revista electrónica no ha sido una tarea sencilla. Un año más tarde no podemos sino confirmar esa opinión.Gracias al decidido trabajo de los autores, revisores y miembros del equipo editorial hemos podido hacerlo. El proceso de revisión de los artículos ha merecido un cuidado, dedicación y tiempo especiales, que hicieron...

  10. Sonidos del Silencio

    Directory of Open Access Journals (Sweden)

    Luz Rodríguez Carranza

    2009-12-01

    Full Text Available La novela ha muerto, afirmaba Alberto Moravia, popularizada, anexada y banalizada por el cine, la televisión, la prensa, la sicología y la sociología. Para Carlos Fuentes en cambio - quien cita a Moravia en 1969 – « lo que ha muerto es sólo la forma burguesa de la novela, el realismo » (17. Basta un viaje rápido por la red para verificar, sin embargo, que la víctima goza de buena salud y que no está confinada en la cultura de masas o en las ciencias sociales : el modelo realista del siglo XIX – y particularmente la creación de tipos representativos de una época, sean éstos promediales o excepcionales - constituye aún la principal preocupación de los escritores y críticos literarios del siglo XXI.

  11. del consumidor mexicano

    Directory of Open Access Journals (Sweden)

    Nadia Huitzilin Jiménez Torres

    2013-01-01

    Full Text Available Pese a que el 80% de la población del mundo vive en mercados emergentes y países en desarrollo, como México, la investigación sobre el consumidor de estos países ha sido insuficiente. El objetivo de este estudio es determinar el perfil del consumidor mexicano en función de variables psicosociológicas como el etnocentrismo, la apertura cultural, el patriotismo, el colectivismo y las características demográficas. Con este propósito se recogió la información de una muestra de 274 consumidores, se realizaron un análisis factorial de sus principales componentes y un análisis cluster con el cual se aglomeró a los individuos en tres grupos con diferentes perfiles psicosociológicos y demográficos.

  12. del noroeste murciano

    Directory of Open Access Journals (Sweden)

    Ma. Luz Tudela Serrano

    2006-01-01

    Full Text Available En la Región de Murcia se está realizando un esfuerzo por aumentar la producción de energías renovables en cumplimiento de los objetivos de Kyoto establecidos para España. Paralelamente, la percepción social acerca de las mismas preocupa cada vez más. En este trabajo, los ciudadanos opinan ante la necesidad de promover el uso e implantación de energías renovables en varias poblaciones afectadas del noroeste. Emplazamientos idóneos, la conservación de los valores naturales y paisajísticos del entorno y las necesidades socioeconómicas de la zona se suman a un uso racional de estas energías y un desarrollo tecnológico paralelo para alcanzar un desarrollo sostenible.

  13. Lo siniestro del enigma.

    Directory of Open Access Journals (Sweden)

    Victoria Eugenia Diaz.

    1999-11-01

    Full Text Available En "El nacimiento de la filosofía griega", Giorgio Colli nos muestra una faceta tenebrosa del enigma. El dios Apolo, de naturaleza ilimitada, insondable, caprichosa, plantea al hombre enigmas que lo enfrentan con el sufrimiento y con la muerte. Allí, Edipo se confronta con enigmas enviados por el dios en los que se pone en juego su propia existencia. Tiempo después, en el transcurrir del siglo XX, reaparece una nueva forma de este dios arbitrario y arrogante: el desaparecedor de personas, ese inmoderado que impone moderación, borra con su acto un cuerpo, una imagen, un nombre, y formula un nuevo enigma siniestro que enfrenta otra vez al hombre con el dolor y con la muerte.

  14. Carta del Editor

    Directory of Open Access Journals (Sweden)

    Luis Eladio Proaño

    2015-01-01

    Full Text Available El aparecimiento del periodista digital y la educación superior en su formación, el cine indígena y la resistencia cultural, más los Grammy latinos, son temas protagónicos de este número. Se suman la prensa en el combate de piráticas corruptas, los errores de la comunicación del presidente URIBE en el referendo, el fútbol y las Relaciones Públicas en España, la libertad de prensa encarcelada, el Internet y la sociedad de la Información y México: profesiones emergentes para los comunicadores, completan la edición.

  15. Percepcion multisensorial del sabor

    Directory of Open Access Journals (Sweden)

    Charles Spence

    2010-12-01

    Full Text Available La investigación sobre la integración multisensorial de los estímulos auditivos, visuales y táctiles nos está ayudando a entender el funcionamiento de la percepción del sabor. Este conocimiento está teniendo ya un impacto sobre el diseño de alimentos y bebidas, desde los productos que compramos en un supermercado hasta aquellos que encontramos en los restaurantes con estrellas Michelin.

  16. Estado Nutricional del Yodo.

    Directory of Open Access Journals (Sweden)

    Hernando Vargas Uricoechea

    2015-06-01

    Full Text Available INTRODUCCIÓN: Los Desórdenes por Deficiencia de Yodo son un problema serio de salud pública, con cerca de 2 mil millones de personas a riesgo de padecerlos, pudiendo causar bocio neonatal, cretinismo, retardo mental, hipotiroidismo, entre otros. Estos desórdenes son aún prevalentes, y en algunos casos los esfuerzos para su erradicación se han traducido en aumento del riesgo de exceso poblacional de yodo y autoinmunidad tiroidea. En Colombia, se desconoce el estado real de yodo en la población. OBJETIVOS: Determinar la mediana de la yoduría en población escolar, y de los hábitos del consumo de sal, función y parámetros de autoinmunidad tiroidea, y cociente intelectual. MATERIALES Y MÉTODOS: Estudio basado en la comunidad, de corte transversal. Se evaluaron las variables sociodemográficas, la frecuencia de bocio y los niveles de TSH, anti-TPO, anti-Tg, anti-TSHR, yoduria, test de factor G de Cattell, y hábitos del consumo de sal. RESULTADOS: El consumo de sal promedio persona/día fue de 18,13 g. El 37,9% presentó bocio. 36,1% tenían un valor límite en el cociente intelectual. La mediana de yoduria fue de 510,3 μg/L. El 42,75% tuvo anti-TPO positivos, y el 2,87% anti-Tg positivos. El 10% presentó niveles de TSH elevados. CONCLUSIÓN: En escolares de zona urbana, hay un exceso en la mediana de yoduria, pudiendo explicarse por el alto consumo de sal. La alta prevalencia de autoinmunidad tiroidea y bocio, junto al alto nivel de la TSH, puede ser consecuencia del exceso en la ingesta de sal y de otros factores medioambientales/ hereditarios.

  17. El lenguaje del pensamiento

    Directory of Open Access Journals (Sweden)

    Alberto Andreu Marín

    2017-09-01

    Full Text Available ¿Somos capaces de interpretar las señales eléctricas que genera nuestro cerebro cuando estamos pensando? Lo que a priori parece ciencia ficción comienza a ser factible gracias a los avances recientes en técnicas de registro cerebral y en aprendizaje automático. Nos encontramos en el inicio de una nueva era en lo que al conocimiento del cerebro se refiere.

  18. Fundamentos del saber administrativo

    OpenAIRE

    Paola Podestá Correa; Juan Carlos Jurado Jurado

    2005-01-01

    El presente texto tiene por objetivo delimitar, de manera general, algunos de los conceptos más importantes del saber administrativo; en primera instancia, práctica administrativa y saber administrativo. Estos conceptos están ligados con los que en el texto se denominan fundamentos de la administración, estableciendo consensos sobre algunas expresiones comunes en el lenguaje administrativo, y contribuyendo a la comprensión de estos temas para los estudiantes de los primeros niv...

  19. 22nd Italian Workshop on Neural Nets

    CERN Document Server

    Bassis, Simone; Esposito, Anna; Morabito, Francesco

    2013-01-01

    This volume collects a selection of contributions which has been presented at the 22nd Italian Workshop on Neural Networks, the yearly meeting of the Italian Society for Neural Networks (SIREN). The conference was held in Italy, Vietri sul Mare (Salerno), during May 17-19, 2012. The annual meeting of SIREN is sponsored by International Neural Network Society (INNS), European Neural Network Society (ENNS) and IEEE Computational Intelligence Society (CIS). The book – as well as the workshop-  is organized in three main components, two special sessions and a group of regular sessions featuring different aspects and point of views of artificial neural networks and natural intelligence, also including applications of present compelling interest.

  20. Dynamic decomposition of spatiotemporal neural signals.

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    Luca Ambrogioni

    2017-05-01

    Full Text Available Neural signals are characterized by rich temporal and spatiotemporal dynamics that reflect the organization of cortical networks. Theoretical research has shown how neural networks can operate at different dynamic ranges that correspond to specific types of information processing. Here we present a data analysis framework that uses a linearized model of these dynamic states in order to decompose the measured neural signal into a series of components that capture both rhythmic and non-rhythmic neural activity. The method is based on stochastic differential equations and Gaussian process regression. Through computer simulations and analysis of magnetoencephalographic data, we demonstrate the efficacy of the method in identifying meaningful modulations of oscillatory signals corrupted by structured temporal and spatiotemporal noise. These results suggest that the method is particularly suitable for the analysis and interpretation of complex temporal and spatiotemporal neural signals.

  1. Signal Processing and Neural Network Simulator

    Science.gov (United States)

    Tebbe, Dennis L.; Billhartz, Thomas J.; Doner, John R.; Kraft, Timothy T.

    1995-04-01

    The signal processing and neural network simulator (SPANNS) is a digital signal processing simulator with the capability to invoke neural networks into signal processing chains. This is a generic tool which will greatly facilitate the design and simulation of systems with embedded neural networks. The SPANNS is based on the Signal Processing WorkSystemTM (SPWTM), a commercial-off-the-shelf signal processing simulator. SPW provides a block diagram approach to constructing signal processing simulations. Neural network paradigms implemented in the SPANNS include Backpropagation, Kohonen Feature Map, Outstar, Fully Recurrent, Adaptive Resonance Theory 1, 2, & 3, and Brain State in a Box. The SPANNS was developed by integrating SAIC's Industrial Strength Neural Networks (ISNN) Software into SPW.

  2. Neural networks with discontinuous/impact activations

    CERN Document Server

    Akhmet, Marat

    2014-01-01

    This book presents as its main subject new models in mathematical neuroscience. A wide range of neural networks models with discontinuities are discussed, including impulsive differential equations, differential equations with piecewise constant arguments, and models of mixed type. These models involve discontinuities, which are natural because huge velocities and short distances are usually observed in devices modeling the networks. A discussion of the models, appropriate for the proposed applications, is also provided. This book also: Explores questions related to the biological underpinning for models of neural networks\\ Considers neural networks modeling using differential equations with impulsive and piecewise constant argument discontinuities Provides all necessary mathematical basics for application to the theory of neural networks Neural Networks with Discontinuous/Impact Activations is an ideal book for researchers and professionals in the field of engineering mathematics that have an interest in app...

  3. International Conference on Artificial Neural Networks (ICANN)

    CERN Document Server

    Mladenov, Valeri; Kasabov, Nikola; Artificial Neural Networks : Methods and Applications in Bio-/Neuroinformatics

    2015-01-01

    The book reports on the latest theories on artificial neural networks, with a special emphasis on bio-neuroinformatics methods. It includes twenty-three papers selected from among the best contributions on bio-neuroinformatics-related issues, which were presented at the International Conference on Artificial Neural Networks, held in Sofia, Bulgaria, on September 10-13, 2013 (ICANN 2013). The book covers a broad range of topics concerning the theory and applications of artificial neural networks, including recurrent neural networks, super-Turing computation and reservoir computing, double-layer vector perceptrons, nonnegative matrix factorization, bio-inspired models of cell communities, Gestalt laws, embodied theory of language understanding, saccadic gaze shifts and memory formation, and new training algorithms for Deep Boltzmann Machines, as well as dynamic neural networks and kernel machines. It also reports on new approaches to reinforcement learning, optimal control of discrete time-delay systems, new al...

  4. Decentralized neural control application to robotics

    CERN Document Server

    Garcia-Hernandez, Ramon; Sanchez, Edgar N; Alanis, Alma y; Ruz-Hernandez, Jose A

    2017-01-01

    This book provides a decentralized approach for the identification and control of robotics systems. It also presents recent research in decentralized neural control and includes applications to robotics. Decentralized control is free from difficulties due to complexity in design, debugging, data gathering and storage requirements, making it preferable for interconnected systems. Furthermore, as opposed to the centralized approach, it can be implemented with parallel processors. This approach deals with four decentralized control schemes, which are able to identify the robot dynamics. The training of each neural network is performed on-line using an extended Kalman filter (EKF). The first indirect decentralized control scheme applies the discrete-time block control approach, to formulate a nonlinear sliding manifold. The second direct decentralized neural control scheme is based on the backstepping technique, approximated by a high order neural network. The third control scheme applies a decentralized neural i...

  5. Neural neworks in a management information systems

    Directory of Open Access Journals (Sweden)

    Jana Weinlichová

    2009-01-01

    Full Text Available For having retrospection for all over the data which are used, analyzed, evaluated and for a future incident predictions are used Management Information Systems and Business Intelligence. In case of not to be able to apply standard methods of data processing there can be with benefit applied an Artificial Intelligence. In this article will be referred to proofed abilities of Neural Networks. The Neural Networks is supported by many software products related to provide effective solution of manager issues. Those products are given as primary support for manager issues solving. We were tried to find reciprocally between products using Neural Networks and between Management Information Systems for finding a real possibility of applying Neural Networks as a direct part of Management Information Systems (MIS. In the article are presented possibilities to apply Neural Networks on different types of tasks in MIS.

  6. Current status of the second generation of parabolic trough solar concentrator for heat generation process designed at the IIE; Estado actual de la segunda generacion del concentrador solar de canal parabolico para generacion de calor de proceso disenado en el IIE

    Energy Technology Data Exchange (ETDEWEB)

    Ramos Berumen, Carlos; Ramirez Benitez, Juan Rafael; Beltran Adan, Jose [Instituto de Investigaciones Electricas, Cuernavaca, Morelos (Mexico)]. E-mail: cramos@iie.org.mx; rramirez@iie.org.mx; jose.beltran@iie.org.mx

    2010-11-15

    The transformation industry normally uses thermal energy within its process, it obtains this energy burning fossils fuel, a new option is to use new technologies like the thermal solar technology like the parabolic trough, this is a long parabolic mirror used to reflect the sunlight and focused on an absorber tube with a heat-conducting fluid inside. The Instituto de Investigaciones Electricas (IIE) developed a prototype of parabolic trough that is operating in different industries, in this article are showing some improvements to the design, giving like result the second generation of the prototype of parabolic trough of the IIE. [Spanish] La industria de la transformacion normalmente utiliza energia termica dentro de su proceso, los medios convencionales para obtener esta energia es el quemar combustibles fosiles, una opcion que aplica nuevas tecnologias es el uso de la tecnologia termosolar a concentracion que le permitira a la industria utilizar el sol como fuente de energia primaria. El uso de esta tecnologia permitira a las empresas generar calor de proceso sin contaminar el ambiente, lo que dara como resultado empresas competitivas y autosuficientes. Para alcanzar temperaturas utiles a estas aplicaciones se requiere concentrar la energia solar en un area mas pequena, siendo la tecnologia mas extendida la de canal parabolico, el principio de operacion de esta tecnologia es la de concentrar la radiacion solar en el eje receptor preparado con una pintura especial para una mejor absorcion del calor y una cubierta de vidrio para evitar perdidas termicas, dentro del tubo circula un fluido caloportador el cual lleva el calor util hacia el proceso. El Instituto de Investigaciones Electricas (IIE) desarrollo un prototipo de canal parabolico, actualmente estan operando en diferentes industrias, resultado de estas aplicaciones se llevo a cabo una evaluacion del prototipo, se detectaron algunos puntos de mejoras al diseno, los cuales se exponen en este articulo, dando

  7. Carta del Editor

    Directory of Open Access Journals (Sweden)

    Jorge Aguirre

    2015-01-01

    Full Text Available La crisis de la prensa Argentina a efecto del mal manejo de la economía y las finanzas, ocupa el tema central. Pasa revista a tres temas de actualidad: El aumento de cobertura y difusión de la prensa gratuita; los esfuerzos de los "viejos" diarios por cambiar de apariencia y el caso del diario estadounidense TODAY que hace veinte años dio un cambio revolucionario en la forma de hacer periodismo diario. Se analizan también temas como: el "carisma" de los líderes actuales, los acuerdos entre los medios de comunicación y el gobierno de México para la difusión de planes y programas oficiales y el rol de los medios en el proceso de establecimiento del ALCA. Agrega el tema controversial sobre la Ley de radiodifusión privada, vigente desde la época de la dictadura pinochetista. En este mismo campo de la Radio otro artículo señala las normas para "contar las noticias" con impacto e interés.

  8. Carta del Editor

    Directory of Open Access Journals (Sweden)

    Jorge Mantilla Jarrín

    2015-01-01

    Full Text Available En este número, el módulo Dibujos Animados, recoge las experiencias del primer curso realizado por el CIESPAL con apoyo de la UNICEF sobre la producción de programas educativos y culturales que utilizan este recurso como una opción comunicacional. Se trata de nuevas tecnologías aprovechadas en Cuba y que pueden ser aplicadas en nuestros países. El módulo relativo al medio ambiente habla del periodismo ecológico con importante desarrollo en América Latina, tema de actualidad que requiere preocupación por parte de los medios de comunicación. Incluye entrevistas a Gunter Grass y Jesús Polanco. Gabriel Alba adentra a los lectores en una novedosa forma de usar las computadoras. En el módulo Debate se trata la Economía, cultura y comunicación; La publicidad vía televisión, La evolución del merchandising en las novelas brasileñas ¿Exigir Ética solo al periodista?

  9. Los felinos del canciller

    Directory of Open Access Journals (Sweden)

    Marco Palacios

    1988-01-01

    Full Text Available En la introducción a una de las obras más influyentes de la historiografía colombiana de nuestros tiempos, el autor, Luis Ospina Vásquez, advierte ciertas dificultades inherentes al oficio de historiar la economía: "Otros aspectos del tema son difíciles de tratar por otros motivos: no se puede citar, entre las causas del difícil adelanto económico de cierta región nuestra, llamada por la generosidad de la naturaleza a una gran riqueza; el hecho de que en ella la política se haya reducido con frecuencia a una pugna entre grupos de hampones[...] Y en el supuesto de que se pudiera dar tratamiento adecuado a lo que, al fin y al cabo, es cosa tangible, no muy difícil de percibir y de describir, faltaría aun dar entrada a un elemento sumamente importante, pero este sí difícil de captar y de transmitir: la 'atmósfera', las 'atmósferas' sucesivas del país y sus regiones, elemento esencial en la historia de la evolución económica.

  10. El Museo del Oro

    Directory of Open Access Journals (Sweden)

    Efraín Sánchez Cabra

    2003-09-01

    Full Text Available El 22 de diciembre de 1939 el Banco de la República compró un objeto de oro de 777,7 gramos de peso y 23,5 centímetros de altura que dio origen al Museo del Oro. Era un poporo quimbaya, pieza maestra de la orfebrería prehispánica. Un objeto bello bello que levanta su bruñido vientre globular y su cuello coronado por cuatro cuerpos esféricos sobre una exquisita base de filigrana fundida, y parece flotar en un espacio propio. Quien lo contempla no puede menos que asombrarse, deleitarse y sentir admiración por sus artífices. Detrás de la compra del poporo había una clara preocupación oficial por proteger una riqueza que comenzaba a entenderse como parte del patrimonio nacional. Esta motivación se pone de manifiesto en una serie de documentos relativos a su adquisición.

  11. Llanto del adulto

    Directory of Open Access Journals (Sweden)

    Alegría Majluf

    2013-09-01

    Full Text Available Se presentan los resultados de un primer estudio transcultural del llanto del adulto que comprende 30 países, entre los que se encuentra el Perú. Vingerhoets et al. (1997 de la Universidad de Tilburg, Holanda, analizan las causas, tendencia y frecuencia del llanto, emociones y sentimientos que inducen al llanto, diferencias y similitudes entre los países y los sexos. Los autores encuentran que las mujeres tienden a llorar con más frecuencia e intensidad que los varones, advirtiendo que en algunos países las mujeres establecen mayor relación entre la tendencia al llanto y el ciclo menstrual que en otros. The results of a first cross-cultural study on adult crying in 30 countries including Peru are presented. Vingerhoets et al. (1997 from the University of Tilburg have analyzed motives, tendencies and frequency of crying, emotions and feelings that provoke crying, as well as differences and similarities among countries and sexes. Results show that women have a tendency to cry more frequently and intensively than men. It has also been noted that, in certain countries, there is a link between crying in women and their monthly period.

  12. Carta del Editor

    Directory of Open Access Journals (Sweden)

    Luis Eladio Proaño

    2015-01-01

    Full Text Available Artículo de fondo es un ejemplo de una campaña exitosa de Relaciones Públicas realizada para rescatar a Medellín para el turismo, ahora herida de muerte por el narcotráfico. Reinicia el tema sobre el cine, recordando el aniversario del nacimiento de Luis Buñuel. Y sobre el Nuevo Orden Internacional de la Información, Luis Ramiro Beltrán da respuesta a las múltiples interrogantes planteadas en la controversia surgida alrededor del tema. Se da a conocer cómo era el periódico de ayer, de hoy y del futuro frente al desafío de las nuevas tecnologías. Se señala el camino para hacer publicidad en Internet. El Internet y la radio nuevos actores para un mismo mercado. Y para los interesados en la investigación se trata cómo y cuándo hacer sondeos flash y se cierra con el lenguaje periodístico cuándo el dequeísmo es lícito.

  13. comportamiento del consumidor

    Directory of Open Access Journals (Sweden)

    Erico Rentería Pérez

    2006-01-01

    Full Text Available En este artículo se analiza el posicionamiento exitoso de los profesionales, particularmente los jóvenes, a partir de las nuevas realidades del mundo y del mercado laboral, así como la empleabilidad como constructo, estrategias posibles y, finalmente, una discusión sobre falacias y realidades de discursos sobre mercado de trabajo profesional. La reflexión se liga a dos investigaciones, y a redes de discusión en Brasil y Colombia, que reflexionan sobre las implicaciones y requerimientos estratégicos que marcan el ingreso o permanencia en el mercado de trabajo de profesionales jóvenes, y se reconoce que esto afecta a otros tipos de profesionales. La investigación de Rentería (2006ª sobre Empleabilidad arroja información sobre las dos primeras partes. La de Enríquez y Rentería (2006 sobre Estrategias de aprendizaje y empleabilidad informa sobre la tercera. Apoyan la discusión elementos de psicología y comportamiento del consumidor. Se discute la inclusión social y calidad de vida por el trabajo.

  14. Carta del Editor

    Directory of Open Access Journals (Sweden)

    Luis Eladio Proaño

    2015-01-01

    Full Text Available Abre la revista una retrospectiva de la crisis económica, política y social en la que se precipitó Argentina (2001-2002 y el tratamiento que dieron los medios a esta situación. En opinión se describe el significado de los nuevos paradigmas de Internet como: interactividad, personalidad, multimedialidad, hipertextualidad, actualización, abundancia y mediación. Responde a la cuestión de ¿cómo y cuándo en la prensa latinoamericana sigue imperando la prensa amarilla? Recoge en un artículo los factores que más inciden en el éxito o fracaso de una campaña política. Aborda la implantación de una nueva moneda única en la Unión Europea y sus incidencias. Destaca las consecuencias vividas por México tras el ataque terrorista del 11 de septiembre 2001 y analiza el tratamiento que los medios dan a las informaciones procedentes del Tercer Mundo en Europa. Contesta a la pregunta inquietante sobre las posibilidades del liberalismo económico para garantizar o contrarrestar la libertad de prensa y por último se aclara los mitos y realidades que se han tejido alrededor de Windows XP de Microsoft.

  15. Efeito dos Tratamentos Térmicos de Normalização e de Solubilização na Microestrutura de uma Junta Dissimilar Soldada entre um Tubo de Aço API 5L X-52 e o Inconel 625

    Directory of Open Access Journals (Sweden)

    Jefferson Pinto Soares

    2017-12-01

    Full Text Available Resumo O propósito deste trabalho é comparar as mudanças na microestrutura e na dureza de um tubo de aço API 5L X-52, revestido internamente por soldagem com Inconel 625, após a execução dos tratamentos térmicos de normalização a 1100 °C por 60 min. e resfriamento ao ar, e de solubilização a 1030 °C com aquecimento por indução eletromagnética por 30 s. e resfriamento em água. Foram utilizadas técnicas de microscopia ótica (MO e eletrônica de varredura (MEV, análise por espectroscopia de energia dispersiva (EDS e dureza Vickers. Na condição como soldada, o metal de base (MB teve na zona termicamente afetada (ZTA a formação de zona de grãos grosseiros (ZGG com dureza média de 234 HV. A zona parcialmente diluída (ZPD se apresentou clara, sem contornos de grãos, com alto teor de ferro e dureza média de 370 HV, indicando ser constituída de martensita. No revestimento, a microestrutura é austenítica dendrítica com formação de carbetos de Nb e indícios da presença da fase Laves, com dureza média de 287 HV em suas camadas. Na condição após normalização, a ZTA foi suprimida e houve refino na microestrutura do MB; a ZPD foi mantida com sua morfologia original, porém com redução de cerca de 15% em sua dureza; no revestimento, a microestrutura tornou-se granular, com indício da dissolução da fase Laves e redução de sua dureza de cerca de 26%. Na condição após solubilização, a ZTA do MB foi eliminada, a ZPD manteve sua morfologia e microestrutura original, mas reduziu sua dureza em cerca de 30%; no revestimento, a microestrutura e precipitados foram mantidos, mas houve uma redução da dureza em cerca de 20%. Por fim, este trabalho conclui que ambos os tratamentos térmicos foram considerados benéficos às propriedades do tubo de aço API 5L X-52 revestido internamente com Inconel 625. Promoveram a homogeneização da microestrutura e a redução de dureza na ZTA do MB, significativa redução da

  16. Estudo da soldagem de tubos de aço inoxidável duplex e superduplex na posição 5G Study of the welding of duplex and superduplex stainless steel pipes in the 5G position

    Directory of Open Access Journals (Sweden)

    Pedro Ivo Guimarães de Vasconcellos

    2010-09-01

    Full Text Available Os aços inoxidáveis duplex e superduplex possuem uma microestrutura austeno-ferrítica com fração média de cada fase de cerca 50%. A microestrutura duplex é responsável pelas excelentes propriedades mecânicas, especialmente o limite de escoamento e a tenacidade, e pela elevada resistência a corrosão por pites e sob tensão em meios contendo cloretos. A soldagem destes aços é frequentemente uma operação crítica. Neste trabalho, um tubo de superduplex SAF 2207 foi soldado pelo processo TIG (GTAW no passe de raiz e eletrodo revestido (SMAW nos passes de enchimento, e um tubo de duplex SAF 2205 foi todo soldado pelo processo GTAW. A microestrutura do metal base, zona afetada termicamente (ZTA e metal de solda foi caracterizada e quantificada. As propriedades de tenacidade, resistência a corrosão e composição química foram avaliadas e correlacionadas. Os valores de tenacidade ao impacto Charpy-V foram considerados adequados. Não foi observada a precipitação de intermetálicos, carbonetos e nitretos. O melhor resultado no teste de corrosão da junta soldada de aço inox superduplex, comparado ao duplex, foi atribuído ao baixo teor de ferrita delta na solda e ZTA, e composição química da solda enriquecida em Cr, Mo, W e N.The duplex and superduplex stainless steels have an austenitic-ferritic microstructure with an average fraction of each phase of approximately 50%. This duplex microstructure is responsible for the excellent mechanical properties, specially the yield strength and toughness, and for the improved pitting and stress corrosion cracking resistance in chloride environments. Welding of these steels is often a critical operation. In this work, a superduplex stainless steel SAF 2507 pipe was welded by the GTAW process in the root pass and by SMAW process on filler passes, and one pipe of duplex SAF 2205 was entirely welded by the GTAW process. The microstructure of the base metal, heat affected zone (HAZ and weld

  17. Noradrenergic modulation of neural erotic stimulus perception.

    Science.gov (United States)

    Graf, Heiko; Wiegers, Maike; Metzger, Coraline Danielle; Walter, Martin; Grön, Georg; Abler, Birgit

    2017-09-01

    We recently investigated neuromodulatory effects of the noradrenergic agent reboxetine and the dopamine receptor affine amisulpride in healthy subjects on dynamic erotic stimulus processing. Whereas amisulpride left sexual functions and neural activations unimpaired, we observed detrimental activations under reboxetine within the caudate nucleus corresponding to motivational components of sexual behavior. However, broadly impaired subjective sexual functioning under reboxetine suggested effects on further neural components. We now investigated the same sample under these two agents with static erotic picture stimulation as alternative stimulus presentation mode to potentially observe further neural treatment effects of reboxetine. 19 healthy males were investigated under reboxetine, amisulpride and placebo for 7 days each within a double-blind cross-over design. During fMRI static erotic picture were presented with preceding anticipation periods. Subjective sexual functions were assessed by a self-reported questionnaire. Neural activations were attenuated within the caudate nucleus, putamen, ventral striatum, the pregenual and anterior midcingulate cortex and in the orbitofrontal cortex under reboxetine. Subjective diminished sexual arousal under reboxetine was correlated with attenuated neural reactivity within the posterior insula. Again, amisulpride left neural activations along with subjective sexual functioning unimpaired. Neither reboxetine nor amisulpride altered differential neural activations during anticipation of erotic stimuli. Our results verified detrimental effects of noradrenergic agents on neural motivational but also emotional and autonomic components of sexual behavior. Considering the overlap of neural network alterations with those evoked by serotonergic agents, our results suggest similar neuromodulatory effects of serotonergic and noradrenergic agents on common neural pathways relevant for sexual behavior. Copyright © 2017 Elsevier B.V. and

  18. Estandarización del método de centrifugación en placa para el aislamiento del virus dengue Rapid centrifugation assay standarization for dengue virus isolation

    Directory of Open Access Journals (Sweden)

    Miryam Palomino

    2010-03-01

    Full Text Available Se estandarizó el método de centrifugación en placa, para el aislamiento del virus dengue a partir de muestras de suero humano. Se utilizó la línea celular C6/36-HT determinándose los valores óptimos de velocidad de centrifugación, volumen de inóculo, dilución de suero y tiempo de incubación. Posteriormente, 22 muestras de suero con aislamiento viral positivo y cepas referenciales de los cuatro serotipos del virus dengue, fueron procesadas simultáneamente por el método de centrifugación en placa y el método convencional de cultivo en tubo, los aislamientos fueron tipificados mediante inmunofluorescencia indirecta empleando anticuerpos monoclonales. Se optimizó el método de centrifugación en placa inoculando 200 μL de diluciσn de suero 1/20, centrifugaciσn a 1600 rpm/30 min, presentando sensibilidad de 95,5% a cinco dνas postinoculación. Se concluye que el método de centrifugación en placa mejora el porcentaje de aislamiento, con significativa reducción en tiempo de aislamiento del virus dengue.The plate centrifugation assay was standardized for dengue virus isolation from serum samples. C6/36-HT cells were used determining the optimal values for centrifugation spin speed, inoculum, sera dilution, and incubation time. Then, 22 positive serum samples with viral isolation and viral strains of the four reference dengue virus serotypes were tested simultaneously by the standardized plate centrifugation method and the conventional tube culture. The isolations were typified by indirect immunofluorescent test using monoclonal antibodies. The plate centrifugation method was optimized to 200 μL of inoculum, dilution of sera 1/20, centrifugation speed at 1600 rpm/30 min, and sensitivity of 95,5% after 5 days post-inoculation. We concluded that the plate centrifugation method increased dengue virus isolation, with a significant reduction of the time of isolation for dengue virus.

  19. Inestabilidad compleja del codo

    Directory of Open Access Journals (Sweden)

    Héctor Gabriel Díaz Carrillo

    2014-08-01

    Full Text Available La inestabilidad compleja del codo es de reciente descripción y controversial en sus resultados; es el estado que se deriva del daño estructural y funcional, producido por la incongruencia de las superficies articulares y las estructuras ligamentosas que estabilizan el codo. Se realizó un estudio descriptivo prospectivo, en el período comprendido entre enero de 2011 y abril de 2013, en una muestra no probabilística de ocho pacientes (diez codos, seleccionados según criterios de inclusión y exclusión. Los objetivos fundamentales del estudio fueron: la actualización de conocimientos para el manejo de la enfermedad y la caracterización de los resultados obtenidos en los afectados por esta dolencia que fueron operados en el Hospital Dr. Ernesto Guevara de la Serna de la provincia de Las Tunas. Se analizaron los datos mediante técnicas estadísticas descriptivas y se realizó la evaluación clínica y radiográfica de los lesionados. El tratamiento se ejecutó según los hallazgos y consistió en: reparación ligamentosa, actuación sobre las partes óseas dañadas y colocación de osteosíntesis diversas. La edad promedio fue de 39,2 años y predominó el sexo masculino. A todos se les practicó reparación ligamentosa, siete cupulectomías y seis aplicaciones de cerclajes anti-distractores. Existieron dos reluxaciones y una sepsis local. La amplitud de movimientos fue aceptable dentro del rango compatible, con una buena función ergonómica; de acuerdo a las comparaciones bibliográficas actualizadas que se realizaron. La fijación y reparación de los estabilizadores del codo brindan buenos resultados funcionales. La sistematización en el manejo de la enfermedad, la detección de complicaciones y el arsenal terapéutico disponible son factores a tener en cuenta

  20. Nuevos usos del cemento

    Directory of Open Access Journals (Sweden)

    Páez Balaca, A.

    1977-04-01

    Full Text Available In this article, the evolution of the different systems of transporting and storing submarine oil and its by-products (petroleum gas and natural gas, is dealt with stressing the importance of the use of concrete boats. Due to the high cost of oil pipelines, we have passed from tanks built on land to prestressed concrete tanks which can be berthed at great depths or anchored to the bottom to keep them afloat, it being possible to unmoor them for transferring them. Transporting and storing liquated gas leads US to see the advantages of prestressed concrete over steel, as the latter becomes brittle at low temperatures, whereas the former's strength increases. The different forms and possible sections are analyzed, stressing the great importance of the solution of the double concrete hull with pearlite insulation. Finally, a study is made of «light concretes », not the classical types used as thermal and acoustic insulation, but the semi-heavy ones made with expanded clay, high quality sand and P-450 cement, which technique is not yet as developed in Spain at might be wished.En este artículo se trata la evolución de los distintos sistemas de transporte y almacenamiento del petróleo submarino y sus derivados (gas de petróleo y gas natural, resaltando la importancia del uso de barcos de hormigón. Debido al gran coste de los oleoductos, se ha pasado de los tanques construidos en tierra firme a los depósitos de hormigón pretensado que pueden estar fondeados a gran profundidad o anclados al fondo para mantenerlos flotantes, existiendo la posibilidad de poder desamarrarlos para su traslado. El transporte y almacenamiento del gas licuado nos hace ver las ventajas del hormigón pretensado sobre el acero, pues éste se vuelve quebradizo a bajas temperaturas, mientras aquél aumenta su resistencia. Se analizan las diferentes formas y secciones posibles, destacando la gran importancia de la solución del doble casco de hormigón con

  1. Enfermedad Diverticular del Colon

    Directory of Open Access Journals (Sweden)

    Gonzalo López Escobar

    1991-06-01

    Full Text Available

    Los divertículos del colon han sido reconocidos por varios observadores desde hace más de un siglo, pero en su mayor parte se trataba de casos aislados, hoy se la considera como la enfermedad del siglo XX, la de la era moderna y de los países industrializados y de avanzada tecnología (5,18,33.

    Según el diccionario de la Real Academia Española (11, divertículo, del latín, diverticulum, quiere decir desviación de un camino; y desde el punto de vista anatómico, apéndice hueco y terminado en fondo de saco. (Gráfica No. 1.

    Goligher (17 lo define como la “posada al borde del camino, probablemente un lugar, a menudo, de mala reputación”.

    Historia

    Según Hackford (18, el proceso fué descrito brevemente por Littre a comienzos del siglo XVIII; pero se le atribuye a Cruveilhier la primera descripción como proceso patológico en 1849, quien, además, mencionó: “encontramos, no rara vez, en el sigmoide, entre las bandas de fibras musculares longitudinales, una serie de pequeños tumores piriformes oscuros, que están formados por hernias de la mucosa a través de brechas en la capa muscular” (17.

    Fleischman en 1815 hizo la primera observación de la enfermedad y empleó el término divertículo (45.

    Rokitansky en 1.849, habló de una enfermedad adquirida y consideró que su causa consistía en la constipación (45.

    Virchowen 1853 describió la perisigmoiditis (45.

    En 1859 Sidney Jones informó de una fístula colo-vesical debida a diverticulitis (5,45.

    Loomis en 1870 describe una peritonitis como resultante de una diverticulitis (45.

    En 1877 Ball describió la anatomía patológica de la enfermedad y presentó dos casos de fístula colovesical debidas a diverticulitis (9. Cripps en 1.888 popularizó la colostomía de desviación como tratamiento para la fístula colovesical(18...

  2. Terapia neural como tratamiento contra el dolor en la displasia mamaria cíclica de grado II Neural therapy as pain-relief treatment in grade III cyclic breast dysplasia

    Directory of Open Access Journals (Sweden)

    Orlando R Expósito Reyes

    2007-09-01

    Full Text Available De enero a diciembre de 2004 se realizó un estudio experimental del tipo ensayo clínico de fase II, controlado y monocéntrico, cuyo objetivo fue evaluar la eficacia de la terapia neural en el tratamiento del dolor como manifestación de la displasia mamaria cíclica de grado II en comparación con la terapéutica convencional. Se estudiaron 240 pacientes, que fueron divididos en 4 grupos según el tipo de tratamiento: con terapia neural (grupo I, con vitamina E (grupo II, con progesterona (grupo III y con antiinflamatorios no esteroideos (grupo IV. Se observó mejoría del dolor en más de 60 % del grupo I y fue similar con el uso de la progesterona. Con los antiinflamatorios no esteroideos y la vitamina E hubo diferencias significativas. Se obtuvieron resultados satisfactorios con el empleo de la terapia neural con procaína al 1 %, por lo que pudimos considerarla eficaz en la terapéutica de esta manifestaciónA controlled monocentered experimental study of phase II clinical assay type was carried out from January to December, 2004 to evaluate the effectiveness of neural therapy in treating pain as manifestation of grade II cyclic breast dysplasia in comparison to the conventional therapy. Two hundred and forty patients were studied. They were divided into 4 groups according to the type of treatment: neural therapy (group I; vitamin E (group II; progesterone (group III; and non-steroidal anti-inflammatory drugs (group IV. Pain relief was observed in over 60 % of patients in group I, a result similar to that of group III (progesterone. There were significant differences in groups treated with non-steroidal anti-inflammatory drugs and Vitamin E. The use of neural therapy based on 1% procaine yielded satisfactory results, so we considered it as an effective therapy for pain relief in grade II breast dysplasia

  3. Max Weber o el enigma emocional del origen del capitalismo

    OpenAIRE

    EDUARDO BERICAT ALASTUEY

    2001-01-01

    Se analiza el trabajo clave de Max Weber, La ética protestante y el espíritu del capitalismo, desde la perspectiva de la Sociología de las Emociones. Aunque la inclusión de las emociones de los fenómenos sociales es clave para entender la idea de Weber sobre el dogma de la predestinación, los sociólogos han trivializado el papel de la emoción. Tras detallar la creencia de Weber en que el espíritu del capitalismo parte del conocimiento de que el destino del hombre está predeterminado (la ética...

  4. Sobre el significado del descubrimiento del gen FOXP2

    OpenAIRE

    Longa Martínez, Víctor Manuel

    2006-01-01

    El reciente descubrimiento del gen FOXP2 ha ofrecido la primera evidencia clara de la base genética del lenguaje, mostrando una correlación inequívoca desde la perspectiva genética entre una versión mutada de F0XP2 y los trastornos lingüísticos de diferente tipo sufridos por una familia inglesa, conocida como KE. El objetivo central del presente trabajo es discutir diferentes aspectos relacionados con tal descubrimiento; especialmente, la discusión del significado de FOXP2 con ...

  5. Competitividad sectorial internacional. Caso: sector del cuero y del calzado

    Directory of Open Access Journals (Sweden)

    Diana Carolina Villegas Álvarez

    2007-01-01

    Full Text Available El presente escrito se origina en un trabajo de investigación cuya pretensión fue indagar sobre el nivel de competitividad internacional (C.I, del sector del cuero y del calzado colombiano, mediante la aplicación de indicadores que, a partir de la información estadística de las variables de comercio exterior permiten establecer ciertas relaciones que dan cuenta de la importancia del producto en los mercados de los países de la Comunidad Andina de Naciones (CAN, seleccionados para la comparación.

  6. Tratamento cirúrgico da otite média com efusão: tubo de ventilação versus aplicação tópica de mitomicina C Surgical treatment of otitis media with effusion: ventilation tube versus topical application of mitomycin C

    Directory of Open Access Journals (Sweden)

    Celso G. Becker

    2003-08-01

    Full Text Available O uso do tubo de ventilação (TV da orelha média, tratamento cirúrgico eleito da otite média com efusão (OME, não é isento de complicações, promovendo ainda limitação social pela necessidade de abandono dos banhos de imersão. A mitomicina C (MMC é um antineoblástico, cuja aplicação tópica retarda a fibrose e previne a estenose cicatricial. Em cobaias, retardou o fechamento de timpanotomias, permitindo maior tempo de aeração da orelha média, à semelhança dos tubos de ventilação. FORMA DE ESTUDO: Clínico prospectivo. OBJETIVO: Comparar a eficácia entre timpanotomia, aspirado da efusão e inserção de tubo de ventilação (grupo TV versus timpanotomia, aspirado da efusão e aplicação tópica de mitomicina C (grupo MMC. Comparar o tempo de manutenção da timpanotomia e a incidência de complicações nos dois grupos. RESULTADOS: O grupo MMC apresentou eficácia significativamente menor (52% versus 80% que o grupo TV (p= 0,34. A presença de timpanometria tipo "B" e a ausência de comprometimento do óstio faríngeo tubário pelo tecido adenóide no pré-operatório representaram fatores de mau prognóstico. A aplicação tópica de MMC nas bordas da timpanotomia proporcionou um tempo de abertura da membrana timpânica por duas a três semanas. No grupo TV, a otorréia foi observada em 13,3% dos pacientes. No grupo MMC, apesar da menor eficácia, nenhum paciente apresentou complicações nem sofreu prolongada proibição dos banhos de imersão. CONCLUSÃO: Apesar de concluirmos que o TV apresenta maior eficácia, novos estudos utilizando maior concentração, maior tempo de aplicação ou o uso seriado de MMC no tratamento da otite média com efusão devem ser realizados.The insertion of the ventilation tube (VT, which is the surgical treatment for otitis media with effusion (OME, is not free from complications and also limits social life because of the need of abandoning immersion baths. Mitomycin C is an antineoblastic

  7. Bajo peso al nacer y defectos congénitos en relación con sitios mineros y campos agrícolas en Sonora, México. Prevalencia 2008-2012

    OpenAIRE

    Javier Valdés Hernández; Aldelmo Eloy Reyes Pablo; Eduardo Navarrete Hernández; Sonia Canún Serrano

    2017-01-01

    Existen evidencias de contaminación ambiental debido a minas y campos agrícolas en Sonora, México. El objetivo de este trabajo es estudiar espacialmente la prevalencia de los defectos al nacimiento, los del tubo neural y el bajo peso al nacer en los municipios donde hay minas de metales y en los distritos de riego. Para ello se emplearon las bases de datos de nacimiento y muerte fetal de 2008 a 2012. Se estimaron tasas de prevalencia nacional, estatal, municipal y por localidad. Se utilizó in...

  8. ETHANOL EXPOSURE DISRUPTS CRANIAL NEURAL CREST MIGRATION AND PRIMARY CILIA IN DEVELOPING ZEBRAFISH EMBRYOS

    OpenAIRE

    BORIC BRENET, KATICA ANDREA; BORIC BRENET, KATICA ANDREA

    2012-01-01

    Durante el desarrollo temprano la exposición a etanol (EtOH) puede causar el Síndrome de Alcohol Fetal (SAF), el cual afecta estructuras craneofaciales (CF) y partes del sistema nervioso (SN), ambos derivados de las células de la cresta neural craneal (CCNC). Por lo tanto, proponemos que la migración de las CCNC se ve afectada por la exposición a EtOH. Para determinar si la exposición a EtOH altera la migración celular, incubamos embriones de pez cebra durante 20 horas usando conc...

  9. La impronta del nuevo mundo

    Directory of Open Access Journals (Sweden)

    Rodrigo Lagos Vergara

    1992-05-01

    Full Text Available Cuando nos aprontamos a conmemorar el quinto centenario del Nuevo Mundo, cabe hacer algunas reflexiones acerca de nuestro continente a la luz del lenguaje propio de las artes y la arquitectura a través del tiempo. Hablamos del Nuevo Mundo en la medida que aceptamos, por una parte, la concepción del nuevo espacio generado a partir del encuentro de dos culturas, la precolombina americana y la propiamente europea llegada principalmente a través de España, y, por otra parte, aceptando también que el nuevo continente resulta ser la pieza clave que ayuda definitivamente a configurar un nuevo cosmos que revela al mundo su otro extremo y aquella parte que manifiesta la totalidad en la certeza de que la tierra es un planeta.

  10. Neural Networks in Control Applications

    DEFF Research Database (Denmark)

    Sørensen, O.

    are examined. The models are separated into three groups representing input/output descriptions as well as state space descriptions: - Models, where all in- and outputs are measurable (static networks). - Models, where some inputs are non-measurable (recurrent networks). - Models, where some in- and some...... outputs are non-measurable (recurrent networks with incomplete state information). The three groups are ordered in increasing complexity, and for each group it is shown how to solve the problems concerning training and application of the specific model type. Of particular interest are the model types...... Kalmann filter) representing state space description. The potentials of neural networks for control of non-linear processes are also examined, focusing on three different groups of control concepts, all considered as generalizations of known linear control concepts to handle also non-linear processes...

  11. Primary neural leprosy: systematic review

    Directory of Open Access Journals (Sweden)

    Jose Antonio Garbino

    2013-06-01

    Full Text Available The authors proposed a systematic review on the current concepts of primary neural leprosy by consulting the following online databases: MEDLINE, Lilacs/SciELO, and Embase. Selected studies were classified based on the degree of recommendation and levels of scientific evidence according to the “Oxford Centre for Evidence-based Medicine”. The following aspects were reviewed: cutaneous clinical and laboratorial investigations, i.e. skin clinical exam, smears, and biopsy, and Mitsuda's reaction; neurological investigation (anamnesis, electromyography and nerve biopsy; serological investigation and molecular testing, i.e. serological testing for the detection of the phenolic glycolipid 1 (PGL-I and the polymerase chain reaction (PCR; and treatment (classification criteria for the definition of specific treatment, steroid treatment, and cure criteria.

  12. Neural Tube Defects and Pregnancy

    Directory of Open Access Journals (Sweden)

    Emine Çoşar

    2009-09-01

    Full Text Available OBJECTIVE: Neural tube defects are congenital malformations those mostly causing life-long morbidities. They are prevented by the periconseptional folic acid usage and prenatal diagnostic methods. MATERIALS-METHODS: Pregnants from Afyonkarahisar and neighbourhood cities applied to our hospital and determined NTD, were investigated. RESULTS: In our obstetrics clinic 1403 delivery were made and 43 of them had fetus with NTD. Among these fetuses 41.3% had meningomyelocel, 17.4% had meningocel, 21.7% had encephalocel, 8.7% had unencephali and 4.3% had iniencephali. CONCLUSION: Incidence of NTD is high in our region and geographic region, nutrition and other socioeconomic factors may be related to the high incidence. Education of the mother and periconceptional folic acid usage may reduce teh incidence of NTD.

  13. Collision avoidance using neural networks

    Science.gov (United States)

    Sugathan, Shilpa; Sowmya Shree, B. V.; Warrier, Mithila R.; Vidhyapathi, C. M.

    2017-11-01

    Now a days, accidents on roads are caused due to the negligence of drivers and pedestrians or due to unexpected obstacles that come into the vehicle’s path. In this paper, a model (robot) is developed to assist drivers for a smooth travel without accidents. It reacts to the real time obstacles on the four critical sides of the vehicle and takes necessary action. The sensor used for detecting the obstacle was an IR proximity sensor. A single layer perceptron neural network is used to train and test all possible combinations of sensors result by using Matlab (offline). A microcontroller (ARM Cortex-M3 LPC1768) is used to control the vehicle through the output data which is received from Matlab via serial communication. Hence, the vehicle becomes capable of reacting to any combination of real time obstacles.

  14. Neural networks: a biased overview

    International Nuclear Information System (INIS)

    Domany, E.

    1988-01-01

    An overview of recent activity in the field of neural networks is presented. The long-range aim of this research is to understand how the brain works. First some of the problems are stated and terminology defined; then an attempt is made to explain why physicists are drawn to the field, and their main potential contribution. In particular, in recent years some interesting models have been introduced by physicists. A small subset of these models is described, with particular emphasis on those that are analytically soluble. Finally a brief review of the history and recent developments of single- and multilayer perceptrons is given, bringing the situation up to date regarding the central immediate problem of the field: search for a learning algorithm that has an associated convergence theorem

  15. Efectos colaterales del voto preferente

    Directory of Open Access Journals (Sweden)

    Luis Diego Brenes Villalobos

    2012-07-01

    Full Text Available El artículo describe la multiplicidad de potenciales efectos que la implementación del voto preferente podría acarrear en el ordenamiento jurídico y el sistema de partidos. La primera parte del análisis se dirige a caracterizar y definir el voto preferencial. En segunda instancia, el estudio comprenderá la revista de los efectos colaterales del voto preferente como modalidad de votación.

  16. Application of neural network to CT

    International Nuclear Information System (INIS)

    Ma, Xiao-Feng; Takeda, Tatsuoki

    1999-01-01

    This paper presents a new method for two-dimensional image reconstruction by using a multilayer neural network. Multilayer neural networks are extensively investigated and practically applied to solution of various problems such as inverse problems or time series prediction problems. From learning an input-output mapping from a set of examples, neural networks can be regarded as synthesizing an approximation of multidimensional function (that is, solving the problem of hypersurface reconstruction, including smoothing and interpolation). From this viewpoint, neural networks are well suited to the solution of CT image reconstruction. Though a conventionally used object function of a neural network is composed of a sum of squared errors of the output data, we can define an object function composed of a sum of residue of an integral equation. By employing an appropriate line integral for this integral equation, we can construct a neural network that can be used for CT. We applied this method to some model problems and obtained satisfactory results. As it is not necessary to discretized the integral equation using this reconstruction method, therefore it is application to the problem of complicated geometrical shapes is also feasible. Moreover, in neural networks, interpolation is performed quite smoothly, as a result, inverse mapping can be achieved smoothly even in case of including experimental and numerical errors, However, use of conventional back propagation technique for optimization leads to an expensive computation cost. To overcome this drawback, 2nd order optimization methods or parallel computing will be applied in future. (J.P.N.)

  17. Nonequilibrium landscape theory of neural networks.

    Science.gov (United States)

    Yan, Han; Zhao, Lei; Hu, Liang; Wang, Xidi; Wang, Erkang; Wang, Jin

    2013-11-05

    The brain map project aims to map out the neuron connections of the human brain. Even with all of the wirings mapped out, the global and physical understandings of the function and behavior are still challenging. Hopfield quantified the learning and memory process of symmetrically connected neural networks globally through equilibrium energy. The energy basins of attractions represent memories, and the memory retrieval dynamics is determined by the energy gradient. However, the realistic neural networks are asymmetrically connected, and oscillations cannot emerge from symmetric neural networks. Here, we developed a nonequilibrium landscape-flux theory for realistic asymmetrically connected neural networks. We uncovered the underlying potential landscape and the associated Lyapunov function for quantifying the global stability and function. We found the dynamics and oscillations in human brains responsible for cognitive processes and physiological rhythm regulations are determined not only by the landscape gradient but also by the flux. We found that the flux is closely related to the degrees of the asymmetric connections in neural networks and is the origin of the neural oscillations. The neural oscillation landscape shows a closed-ring attractor topology. The landscape gradient attracts the network down to the ring. The flux is responsible for coherent oscillations on the ring. We suggest the flux may provide the driving force for associations among memories. We applied our theory to rapid-eye movement sleep cycle. We identified the key regulation factors for function through global sensitivity analysis of landscape topography against wirings, which are in good agreements with experiments.

  18. Nonequilibrium landscape theory of neural networks

    Science.gov (United States)

    Yan, Han; Zhao, Lei; Hu, Liang; Wang, Xidi; Wang, Erkang; Wang, Jin

    2013-01-01

    The brain map project aims to map out the neuron connections of the human brain. Even with all of the wirings mapped out, the global and physical understandings of the function and behavior are still challenging. Hopfield quantified the learning and memory process of symmetrically connected neural networks globally through equilibrium energy. The energy basins of attractions represent memories, and the memory retrieval dynamics is determined by the energy gradient. However, the realistic neural networks are asymmetrically connected, and oscillations cannot emerge from symmetric neural networks. Here, we developed a nonequilibrium landscape–flux theory for realistic asymmetrically connected neural networks. We uncovered the underlying potential landscape and the associated Lyapunov function for quantifying the global stability and function. We found the dynamics and oscillations in human brains responsible for cognitive processes and physiological rhythm regulations are determined not only by the landscape gradient but also by the flux. We found that the flux is closely related to the degrees of the asymmetric connections in neural networks and is the origin of the neural oscillations. The neural oscillation landscape shows a closed-ring attractor topology. The landscape gradient attracts the network down to the ring. The flux is responsible for coherent oscillations on the ring. We suggest the flux may provide the driving force for associations among memories. We applied our theory to rapid-eye movement sleep cycle. We identified the key regulation factors for function through global sensitivity analysis of landscape topography against wirings, which are in good agreements with experiments. PMID:24145451

  19. El movimiento del software libre

    OpenAIRE

    Prudencio Óscar Mochi Alemán

    2002-01-01

    El objetivo de este trabajo es describir el surgimiento y desarrollo del movimiento de software libre. Para ello se analizan algunas características importantes que dan cuenta del origen y desarrollo del mismo, así como de sus momentos más críticos y sus tensiones, sus desafíos y sus retos. Otra de las grandes inquietudes de este trabajo, es intentar descifrar cómo el movimiento del software libre y Linux, en su versión más conocida, sobrevivieron y se afirmaron hasta llegar a ...

  20. Analisi del decadimento $W -> \\tau \

    CERN Document Server

    Coscetti, Simone

    Questo lavoro di tesi si e' svolto nell'ambito dell'esperimento CMS a LHC, ed in particolare verte sullo studio delle strategie di identificazione off-line del leptone tau, atteso tra i prodotti di decadimento del bosone di Higgs, cosi' come di altre particelle previste in altri modelli teorici. Il canale utilizzato per testare la procedura di identificazione del tau e' il decadimento semileptonico del bosone vettore W. Infine, sulla base dei risultati ottenuti viene presentata una stima quantitativa della sezione d'urto di produzione pp-> W + X