El coristoma pancreático, o páncreas heterotópico, es una condición rara en gastroenterología. Es... more El coristoma pancreático, o páncreas heterotópico, es una condición rara en gastroenterología. Esta entidad consiste en el hallazgo de tejido pancreático aberrante, en alguna zona del tracto gastrointestinal, sin continuidad vascular o anatómica con el páncreas normal, es poco reportado y presenta sintomatología variable. Presentamos el caso de un individuo de 46 años con dolor abdominal a quien se le encontró mediante exámenes invasivos un divertículo duodenal, el cual al examen histopatológico e inmunohistoquímico mostró un coristoma pancreático.
Most of the easier structural solutions for greater utilization of water resources have already b... more Most of the easier structural solutions for greater utilization of water resources have already been implemented. The principal objective of this paper is to develop a methodology for helping to produce irrigation scheduling policies for the deployment of water resources for agricultural use. We have, therefore, developed WISCHE (Water Irrigation Scheduling), a decision support system for irrigation scheduling in an arborescent network. Computational experience has been implemented with satisfactory results in "La Comunidad de Regantes, Riegos de Levante, Canal 2 nd ", eastern Spain. Its irrigation area covers 2188 Hectares, with 2831 nodes distributed in 20 sectors. Irrigation is needed on a daily basis in five time periods. Network topology, periodical demands and historical consumptions are the inputs and scheduling the hydrants and turns are the output. Assignments must satisfy two types of constraints: the first one based on physical network limitations and the other one based on previous consumptions and demands. In order to deal with the first limitations, a mixed 0−1 separable quadratic program is proposed. Statistical information about previous consumptions on turns demanded and non-attended demands is used to assign a priority to hydrants. Thus, the system favours hydrants which used what they applied for and hydrants which could not be well attended previously.
International series in management science/operations research, 2020
The Sharpe ratio is a way to compare the excess returns (over the risk free asset) of portfolios ... more The Sharpe ratio is a way to compare the excess returns (over the risk free asset) of portfolios for each unit of volatility that is generated by a portfolio. In this paper we introduce a robust Sharpe ratio portfolio under the assumption that the risk free asset is unknown. We propose a robust portfolio that maximizes the Sharpe ratio when the risk free asset is unknown, but is within a given interval. To compute the best Sharpe ratio portfolio all the Sharpe ratios for any risk free asset are considered and compared by using the so-called cross-efficiency evaluation. An explicit expression of the Cross-Eficiency Sharpe ratio portfolio is presented when short selling is allowed.
Iterative Multi-unit Combinatorial Auctions are auctions in which: bidders can express bids in su... more Iterative Multi-unit Combinatorial Auctions are auctions in which: bidders can express bids in successive rounds until a stopping rule is held; there are multiple units of each item; and bids are bundles of items. Data Envelopment Analysis (DEA) is a nonparametric method for measuring the relative efficiency of a set of homogeneous units. In this work, we present an algorithm for solving an iterative multi-unit combinatorial auction in which the auctioneer computes at each round a linear anonymous price for each item by using a DEA model and pushes bidders to express bids according to them. A computational study is carried out in order to check the performance of the proposed design.
RESUMEN: La base de la cordillera volcánica de Guanacaste está conformada, en su mayoría, por una... more RESUMEN: La base de la cordillera volcánica de Guanacaste está conformada, en su mayoría, por una potente secuencia de depósitos piroclásticos de edades entre el Mioceno y el Pleistoceno, las cuales corresponden a las formaciones Bagaces y Liberia. En el presente trabajo la propuesta estratigráfica para cada una de las unidades de la Formación Bagaces se determinó a partir de la composición y variaciones verticales en sus depósitos. Las litofacies fueron caracterizadas mediante el análisis de quince núcleos de perforación, levantamiento de secciones estratigráficas en el campo y la recopilación de análisis de secciones delgadas.
espanolEl volcan Irazu presenta, en sus cuadrantes sur y oeste, numerosas estructuras relacionada... more espanolEl volcan Irazu presenta, en sus cuadrantes sur y oeste, numerosas estructuras relacionadas con antiguos focos de emision de lavas y piroclastos fuera de su foco cuspidal. Una serie de estas estructuras se encuentra asociada a una zona de deformacion extensional que incluye conos piroclasticos como los cerros Nochebuena, Gurdian, Dussan-Quemados y Pasqui. Este ultimo es un cono piroclastico aportillado con coladas, con evidencias de actividad en un espacio temporal mas reciente que 40 000 anos. En este trabajo, se estudia la estructura interna del cono piroclastico Pasqui mediante la creacion de modelos de densidad a partir de datos de gravedad. Los datos de anomalia de Bouguer a un nivel de reduccion de 2 389 m muestran la correlacion espacial del cono Pasqui con una anomalia negativa local de corta longitud de onda y amplitud de aproximadamente 5 mGal. Esta anomalia indica la presencia de material me-nos denso que el entorno del cerro. Se infiere a partir de la geologia local y los resultados de los modelos de densidad, que existe un espesor de al menos 300 m de material piroclastico asociado con el cono. Este material de relativa baja densidad contrasta con el entorno de mayor densidad compuesto por lavas andesiticas y andesitico-basalticas de la Formacion Reventado y lavas asociadas a actividad fisural originadas en focos como el complejo Dussan-Quemados. EnglishIrazu volcano shows several structures on its southern and western flank that are associated with ancient vents of lava and pyroclastic material outside of its summit caldera. A set of these type of structures is related to an extensional deformation zone that includes pyroclastic cones such as Nochebuena, Gurdian, Dussan-Quemados and Pasqui. This last structure is an eroded cone with lava flows which shows record of activity within the last 40 000 years. In this work, we study the internal structure of the Pasqui pyroclastic cone by creating density model from gravity data. The Bouguer anomaly data reduced to an altitude of 2,389 m, show a spatial correlation of the Pasqui cone with a local negative gravity anomaly with a short wavelength and an amplitude of approximately 5 mGal. This anomaly is indicative of the presence of material with a lower density than its sorroundings. From the density models, we infer the presence of pyroclastic material associated with the cone with a thickness of at least 300 m. This material of relative lower density, contrasts with the surroundings of the cone composed of andesitic and andesitic-basaltic lavas of the Reventado Formation and lavas originated by fissures from vents such as the Dussan-Quemados complex.
American Journal of Tropical Medicine and Hygiene, 1997
Risk factors for cutaneous leishmaniasis were identified from a comparative study of transmission... more Risk factors for cutaneous leishmaniasis were identified from a comparative study of transmission rates in 27 villages in the Departments of Lima, Ancash, and Piura in Peru. To evaluate regression analysis as a tool for the incrimination of sand fly vectors in the absence of other biologic evidence, univariate and multivariate logistic regression analyses were used to identify which of 14 variables (the abundance of nine sand fly species, four social factors, and region) predicted transmission rates in villages (incidence, active prevalence, or cumulative prevalence). In general, suspected or proven vectors (e.g., Lutzomyia peruensis) had the strongest associations with transmission rate, indicating that regression is a useful supplementary method of incriminating vectors. Regression was then used to quantify the importance of suspected risk factors. Transmission rate increased with the abundance of Lu. peruensis, Lu. ayacuchensis, Lu. noguchii, and, to a lesser extent, Lu. verrucarum and transmission was higher among villagers who slept more frequently in temporary shelters in crop areas. There were also weak effects of the number of dogs/ person (negative) and the number of persons/household (positive). Linear regressions failed to detect a threshold sand fly density below which transmission ceases. The minimal adequate multiple regression model explained 82% of the variance in village incidence rates. This model was used to predict the effect on incidence of reducing each of the four suspected vectors in northern and southern Peru. The results indicate that vector control programs in the south should aim at Lu. peruensis, Lu. verrucarum, and Lu. noguchii, but focus on Lu. ayacuchensis in the north.
Food allergy is defined as an abnormal immunological reaction to food proteins, which causes an a... more Food allergy is defined as an abnormal immunological reaction to food proteins, which causes an adverse clinical reaction. Most of the people become tolerant to many foods; however some time these tolerances fail and become an immunologic reaction. This is the first clinical expression of allergy, beginning with dermal o gastric manifestations and continues with asthma and rhinitis (the allergy march) and represents a very severe health problem, not only for many children and parents, but also for the entire medical and paramedical community. The evaluation of a child with suspected food allergy includes detailed medical history, physical examination, screening tests and response to elimination diet and to oral food challenge. None of the screening tests, alone or in combination, can definitively diagnose or exclude it. Regarding to the differential diagnosis, the clinician must know the different groups of foods. The treatment includes the exclusion of the involved food and the use of symptomatic medication when it is needed.
En el presente estudio se ha valorado cuantitativamente en plasma determinados parametros inmunop... more En el presente estudio se ha valorado cuantitativamente en plasma determinados parametros inmunopatologicos como son los inmunocomplejos circulantes y los factores reumatoides de los isotipos igm e iga, en la leishmaniosis visceral canina, partiendo de una poblacion de 82 perros enfermos y un grupo control de 25 perros sanos. para ello se ha desarrollado una tecnica de determinacion elisa amplificada con el sistema avidina biotina, modificada segun el parametro medido. en los perros con leishmaniosis hemos obtenido para los icc-igm un valor medio de d.o. de 1,024+0,049, frente a una media de 0,628 + 0,040 en los perros sanos, que se demuestra estadisticamente inferior a la de los perros enfermos (prueba de - kruskall-wallis con p<6,106x10 elevado a -5). no existen diferencias estadisticamente significativas al comparar los perros por sexo y edad, ni en el grupo de enfermos ni en el grupo control de perros sanos. cuando se estudia la presencia de icc-iga los perros enfermos presentan un valor medio de d.o. de 0,501 +- 0,015 frente a la de 0,203 +- 0,011 de los perros sanos. se demuestran diferencias estadisticamente significativas entre ambas medias (prueba de kruskal-wallis con p<2,658x10 elevado a -5), mientras que no existen diferencias significativas en relacion a la edad ni al sexo, ni en enfermos ni en sanos. al estudiar los fr-igm, se describe una d.o. media de 0,431+-0,011 en perros enfermos y de 0,213+-0,029 en perros sanos. la prueba de kruskall-wallis muestra diferencias estadisticamente significativas entre ambas medias (p<4,039x10 elevado a -5). por el contrario los factores sexo y edad no aportan diferencias estadisticamente significativas entre los diferentes grupos. en el caso del factor reumatoide iga, se obtiene una d.o. media de 0,219 +- 0,006 para perros enfermos y de 0,1508 +- 0,007 para el grupo control sano. tambien se demuestran diferencias estadisticamente significativas al compararlas (p&
El coristoma pancreático, o páncreas heterotópico, es una condición rara en gastroenterología. Es... more El coristoma pancreático, o páncreas heterotópico, es una condición rara en gastroenterología. Esta entidad consiste en el hallazgo de tejido pancreático aberrante, en alguna zona del tracto gastrointestinal, sin continuidad vascular o anatómica con el páncreas normal, es poco reportado y presenta sintomatología variable. Presentamos el caso de un individuo de 46 años con dolor abdominal a quien se le encontró mediante exámenes invasivos un divertículo duodenal, el cual al examen histopatológico e inmunohistoquímico mostró un coristoma pancreático.
Most of the easier structural solutions for greater utilization of water resources have already b... more Most of the easier structural solutions for greater utilization of water resources have already been implemented. The principal objective of this paper is to develop a methodology for helping to produce irrigation scheduling policies for the deployment of water resources for agricultural use. We have, therefore, developed WISCHE (Water Irrigation Scheduling), a decision support system for irrigation scheduling in an arborescent network. Computational experience has been implemented with satisfactory results in "La Comunidad de Regantes, Riegos de Levante, Canal 2 nd ", eastern Spain. Its irrigation area covers 2188 Hectares, with 2831 nodes distributed in 20 sectors. Irrigation is needed on a daily basis in five time periods. Network topology, periodical demands and historical consumptions are the inputs and scheduling the hydrants and turns are the output. Assignments must satisfy two types of constraints: the first one based on physical network limitations and the other one based on previous consumptions and demands. In order to deal with the first limitations, a mixed 0−1 separable quadratic program is proposed. Statistical information about previous consumptions on turns demanded and non-attended demands is used to assign a priority to hydrants. Thus, the system favours hydrants which used what they applied for and hydrants which could not be well attended previously.
International series in management science/operations research, 2020
The Sharpe ratio is a way to compare the excess returns (over the risk free asset) of portfolios ... more The Sharpe ratio is a way to compare the excess returns (over the risk free asset) of portfolios for each unit of volatility that is generated by a portfolio. In this paper we introduce a robust Sharpe ratio portfolio under the assumption that the risk free asset is unknown. We propose a robust portfolio that maximizes the Sharpe ratio when the risk free asset is unknown, but is within a given interval. To compute the best Sharpe ratio portfolio all the Sharpe ratios for any risk free asset are considered and compared by using the so-called cross-efficiency evaluation. An explicit expression of the Cross-Eficiency Sharpe ratio portfolio is presented when short selling is allowed.
Iterative Multi-unit Combinatorial Auctions are auctions in which: bidders can express bids in su... more Iterative Multi-unit Combinatorial Auctions are auctions in which: bidders can express bids in successive rounds until a stopping rule is held; there are multiple units of each item; and bids are bundles of items. Data Envelopment Analysis (DEA) is a nonparametric method for measuring the relative efficiency of a set of homogeneous units. In this work, we present an algorithm for solving an iterative multi-unit combinatorial auction in which the auctioneer computes at each round a linear anonymous price for each item by using a DEA model and pushes bidders to express bids according to them. A computational study is carried out in order to check the performance of the proposed design.
RESUMEN: La base de la cordillera volcánica de Guanacaste está conformada, en su mayoría, por una... more RESUMEN: La base de la cordillera volcánica de Guanacaste está conformada, en su mayoría, por una potente secuencia de depósitos piroclásticos de edades entre el Mioceno y el Pleistoceno, las cuales corresponden a las formaciones Bagaces y Liberia. En el presente trabajo la propuesta estratigráfica para cada una de las unidades de la Formación Bagaces se determinó a partir de la composición y variaciones verticales en sus depósitos. Las litofacies fueron caracterizadas mediante el análisis de quince núcleos de perforación, levantamiento de secciones estratigráficas en el campo y la recopilación de análisis de secciones delgadas.
espanolEl volcan Irazu presenta, en sus cuadrantes sur y oeste, numerosas estructuras relacionada... more espanolEl volcan Irazu presenta, en sus cuadrantes sur y oeste, numerosas estructuras relacionadas con antiguos focos de emision de lavas y piroclastos fuera de su foco cuspidal. Una serie de estas estructuras se encuentra asociada a una zona de deformacion extensional que incluye conos piroclasticos como los cerros Nochebuena, Gurdian, Dussan-Quemados y Pasqui. Este ultimo es un cono piroclastico aportillado con coladas, con evidencias de actividad en un espacio temporal mas reciente que 40 000 anos. En este trabajo, se estudia la estructura interna del cono piroclastico Pasqui mediante la creacion de modelos de densidad a partir de datos de gravedad. Los datos de anomalia de Bouguer a un nivel de reduccion de 2 389 m muestran la correlacion espacial del cono Pasqui con una anomalia negativa local de corta longitud de onda y amplitud de aproximadamente 5 mGal. Esta anomalia indica la presencia de material me-nos denso que el entorno del cerro. Se infiere a partir de la geologia local y los resultados de los modelos de densidad, que existe un espesor de al menos 300 m de material piroclastico asociado con el cono. Este material de relativa baja densidad contrasta con el entorno de mayor densidad compuesto por lavas andesiticas y andesitico-basalticas de la Formacion Reventado y lavas asociadas a actividad fisural originadas en focos como el complejo Dussan-Quemados. EnglishIrazu volcano shows several structures on its southern and western flank that are associated with ancient vents of lava and pyroclastic material outside of its summit caldera. A set of these type of structures is related to an extensional deformation zone that includes pyroclastic cones such as Nochebuena, Gurdian, Dussan-Quemados and Pasqui. This last structure is an eroded cone with lava flows which shows record of activity within the last 40 000 years. In this work, we study the internal structure of the Pasqui pyroclastic cone by creating density model from gravity data. The Bouguer anomaly data reduced to an altitude of 2,389 m, show a spatial correlation of the Pasqui cone with a local negative gravity anomaly with a short wavelength and an amplitude of approximately 5 mGal. This anomaly is indicative of the presence of material with a lower density than its sorroundings. From the density models, we infer the presence of pyroclastic material associated with the cone with a thickness of at least 300 m. This material of relative lower density, contrasts with the surroundings of the cone composed of andesitic and andesitic-basaltic lavas of the Reventado Formation and lavas originated by fissures from vents such as the Dussan-Quemados complex.
American Journal of Tropical Medicine and Hygiene, 1997
Risk factors for cutaneous leishmaniasis were identified from a comparative study of transmission... more Risk factors for cutaneous leishmaniasis were identified from a comparative study of transmission rates in 27 villages in the Departments of Lima, Ancash, and Piura in Peru. To evaluate regression analysis as a tool for the incrimination of sand fly vectors in the absence of other biologic evidence, univariate and multivariate logistic regression analyses were used to identify which of 14 variables (the abundance of nine sand fly species, four social factors, and region) predicted transmission rates in villages (incidence, active prevalence, or cumulative prevalence). In general, suspected or proven vectors (e.g., Lutzomyia peruensis) had the strongest associations with transmission rate, indicating that regression is a useful supplementary method of incriminating vectors. Regression was then used to quantify the importance of suspected risk factors. Transmission rate increased with the abundance of Lu. peruensis, Lu. ayacuchensis, Lu. noguchii, and, to a lesser extent, Lu. verrucarum and transmission was higher among villagers who slept more frequently in temporary shelters in crop areas. There were also weak effects of the number of dogs/ person (negative) and the number of persons/household (positive). Linear regressions failed to detect a threshold sand fly density below which transmission ceases. The minimal adequate multiple regression model explained 82% of the variance in village incidence rates. This model was used to predict the effect on incidence of reducing each of the four suspected vectors in northern and southern Peru. The results indicate that vector control programs in the south should aim at Lu. peruensis, Lu. verrucarum, and Lu. noguchii, but focus on Lu. ayacuchensis in the north.
Food allergy is defined as an abnormal immunological reaction to food proteins, which causes an a... more Food allergy is defined as an abnormal immunological reaction to food proteins, which causes an adverse clinical reaction. Most of the people become tolerant to many foods; however some time these tolerances fail and become an immunologic reaction. This is the first clinical expression of allergy, beginning with dermal o gastric manifestations and continues with asthma and rhinitis (the allergy march) and represents a very severe health problem, not only for many children and parents, but also for the entire medical and paramedical community. The evaluation of a child with suspected food allergy includes detailed medical history, physical examination, screening tests and response to elimination diet and to oral food challenge. None of the screening tests, alone or in combination, can definitively diagnose or exclude it. Regarding to the differential diagnosis, the clinician must know the different groups of foods. The treatment includes the exclusion of the involved food and the use of symptomatic medication when it is needed.
En el presente estudio se ha valorado cuantitativamente en plasma determinados parametros inmunop... more En el presente estudio se ha valorado cuantitativamente en plasma determinados parametros inmunopatologicos como son los inmunocomplejos circulantes y los factores reumatoides de los isotipos igm e iga, en la leishmaniosis visceral canina, partiendo de una poblacion de 82 perros enfermos y un grupo control de 25 perros sanos. para ello se ha desarrollado una tecnica de determinacion elisa amplificada con el sistema avidina biotina, modificada segun el parametro medido. en los perros con leishmaniosis hemos obtenido para los icc-igm un valor medio de d.o. de 1,024+0,049, frente a una media de 0,628 + 0,040 en los perros sanos, que se demuestra estadisticamente inferior a la de los perros enfermos (prueba de - kruskall-wallis con p<6,106x10 elevado a -5). no existen diferencias estadisticamente significativas al comparar los perros por sexo y edad, ni en el grupo de enfermos ni en el grupo control de perros sanos. cuando se estudia la presencia de icc-iga los perros enfermos presentan un valor medio de d.o. de 0,501 +- 0,015 frente a la de 0,203 +- 0,011 de los perros sanos. se demuestran diferencias estadisticamente significativas entre ambas medias (prueba de kruskal-wallis con p<2,658x10 elevado a -5), mientras que no existen diferencias significativas en relacion a la edad ni al sexo, ni en enfermos ni en sanos. al estudiar los fr-igm, se describe una d.o. media de 0,431+-0,011 en perros enfermos y de 0,213+-0,029 en perros sanos. la prueba de kruskall-wallis muestra diferencias estadisticamente significativas entre ambas medias (p<4,039x10 elevado a -5). por el contrario los factores sexo y edad no aportan diferencias estadisticamente significativas entre los diferentes grupos. en el caso del factor reumatoide iga, se obtiene una d.o. media de 0,219 +- 0,006 para perros enfermos y de 0,1508 +- 0,007 para el grupo control sano. tambien se demuestran diferencias estadisticamente significativas al compararlas (p&
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