691 research outputs found

    Flood Risk Management in Mexico

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    Mexico receives an average annual rainfall of 740 mm, which are distributed in the hydrological cycle as follows: 72% evapotranspiration, 21% becomes runoff and 6% as aquifer recharge. Within the Mexican territory, exist a great diversity of climates and high spatial and temporal variability in water resources availability. In the period 2000–2015, damages from hydrometeorological phenomena in Mexico represented between 60 and 99% of total damages and losses at national level due to natural and socioorganizational events. Considering global climate change impact on the selection, design and implementation of flood control measures, represents a major challenge, since the level of certainty regarding its influence on the variables involved, remains insufficient. This chapter provides a description of the main elements directly linked to flooding in México, such as a high spatial and temporal variability in water resources availability and presence of tropical cyclones in both coasts and climate change. A brief summary of the main disasters caused by hydrometeorological phenomena, the annual cost of the damages, the main non‐structural measures for flood control and the intervention from the Mexican Institute of Water Technology in the use, development and spread of technology focused on flood risk management are also included

    Explosive first-order transition to synchrony in networked chaotic oscillators

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    Critical phenomena in complex networks, and the emergence of dynamical abrupt transitions in the macroscopic state of the system are currently a subject of the outmost interest. We report evidence of an explosive phase synchronization in networks of chaotic units. Namely, by means of both extensive simulations of networks made up of chaotic units, and validation with an experiment of electronic circuits in a star configuration, we demonstrate the existence of a first order transition towards synchronization of the phases of the networked units. Our findings constitute the first prove of this kind of synchronization in practice, thus opening the path to its use in real-world applications.Comment: Phys. Rev. Lett. in pres

    Video semantic content analysis framework based on ontology combined MPEG-7

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    The rapid increase in the available amount of video data is creating a growing demand for efficient methods for understanding and managing it at the semantic level. New multimedia standard, MPEG-7, provides the rich functionalities to enable the generation of audiovisual descriptions and is expressed solely in XML Schema which provides little support for expressing semantic knowledge. In this paper, a video semantic content analysis framework based on ontology combined MPEG-7 is presented. Domain ontology is used to define high level semantic concepts and their relations in the context of the examined domain. MPEG-7 metadata terms of audiovisual descriptions and video content analysis algorithms are expressed in this ontology to enrich video semantic analysis. OWL is used for the ontology description. Rules in Description Logic are defined to describe how low-level features and algorithms for video analysis should be applied according to different perception content. Temporal Description Logic is used to describe the semantic events, and a reasoning algorithm is proposed for events detection. The proposed framework is demonstrated in sports video domain and shows promising results

    Dispositivos coaxiales micromecanizados para banda milimétrica

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    This paper presents compact micromachined coaxial devices for millimeter wave applications at U and V bands. The coaxial center conductor is suspende d in air by short circuits to the outer conductor. The designs include a suspended transmission line, two narrowband filters and a diplexer.Peer ReviewedPostprint (published version

    Fasting enhances pyroglutamyl peptidase II activity in tanycytes of the mediobasal hypothalamus of male adult rats

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    Fasting down-regulates the hypothalamus-pituitary-thyroid (HPT) axis activity through a reduction of TRH synthesis in neurons of the parvocellular paraventricular nucleus of the hypothalamus (PVN). These TRH neurons project to the median eminence (ME), where TRH terminals are close to the cytoplasmic extensions of β2 tanycytes. Tanycytes express pyroglutamyl peptidase II (PPII), the TRH-degrading ectoenzyme that controls the amount of TRH that reaches the anterior pituitary. We tested the hypothesis that regulation of ME PPII activity is another mechanism by which fasting affects the activity of the HPT axis. Semiquantitative in situ hybridization histochemistry data indicated that PPII and deiodinase 2 mRNA levels increased in tanycytes after 48 hours of fasting. This increase was transitory, followed by an increase of PPII activity in the ME, and a partial reversion of the reduction in PVN pro-TRH mRNA levels and the number of TRH neurons detected by immunohistochemistry. In fed animals, adrenalectomy and corticosterone treatment did not change ME PPII activity 72 hours later. Methimazole-induced hypothyroidism produced a profound drop in tanycytes PPII mRNA levels, which was reverted by 3 days of treatment with T4. The activity of thyroliberinase, the serum isoform of PPII, was increased at most fasting time points studied. We conclude that delayed increases in both the ME PPII as well as the thyroliberinase activities in fasted male rats may facilitate the maintenance of the deep down-regulation of the HPT axis function, despite a partial reactivation of TRH expression in the PVN

    Evaluación del grado de queratinización y el recuento de AgNORs en citología exfoliativa de mucosa oral normal de individuos fumadores y no fumadores

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    Objetivos. En individuos fumadores con mucosa oral clínicamente sana, se han observado cambios citológicos como una mayor queratinización, existiendo también reportes de un mayor grado de actividad nucleolar. En estos estudios, las células para frotis se han obtenido por medio de espátula de madera. Nuestro objetivo es evaluar la profundidad de muestras citológicas de mucosa oral obtenidas con cepillo para frotis (endobrush) y comparar el grado de queratinización y la actividad nucleolar en pacientes fumadores y no fumadores. Diseño del estudio. Se obtuvieron frotis de mucosa oral de borde de lengua clínicamente normal de 30 individuos fumadores y 30 no fumadores, utilizando espátula de madera y endobrush. Las muestras fueron teñidas con Papanicolaou y con la tinción AgNORs. Resultados. Con la espátula de madera se obtuvo un mayor porcentaje de células epiteliales superficiales anucleadas (P= 0.016) y con el endobrush se obtuvieron células más profundas (tipo intermedias) (P= 0.035). Los individuos fumadores presentaron un mayor porcentaje de células superficiales anucleadas con ambas técnicas, diferencia que fue estadísticamente significativa con la técnica endobrush (P=0.005). El promedio de AgNORs en las células nucleadas fue mayor en los individuos fumadores (3.83) que en los no fumadores (2.79) (P= 0.003). Conclusiones. El endobrush permite obtener células de estratos más profundos. Los individuos fumadores con mucosa clínicamente normal presentan un mayor porcentaje de células queratinizadas y una mayor actividad nucleolar, sugiriendo que el consumo de cigarrillo influye en la actividad celular de la mucosa del borde de lengua.Objetive.In smokers with clinically normal buccal mucosa, cytological changes such as increased keratinization, and higher nucleolar activity have been observed. In these studies the cells for cytological smears were obtained with a wooden spatula. Our objectives were to evaluate the depth of cytological smears of oral mucosa obtained with both a brush (endobrush) and a wooden spatula, and to compare the degree of keratinization and the nucleolar activity in smokers and non-smokers. Design. We obtained cytological smears of clinically normal lateral tongues of 30 smokers and 30 non-smokers using both a wooden spatula and endobrush. The samples were dyed with Papanicolaou and the AgNORs. Results. With the wooden spatula we found a greater percentage of enucleated superficial epithelial cells (P = 0.016) and deeper cells were obtained with an endobrush (intermediate cells) (P =0.035). The smokers showed a greater percentage of enucleated superficial cells with both techniques, however this difference was significantly greater with Endobrush (P=0.005). The average of AgNORs in the nucleated cells was greater in smokers (3.83) than in non-smokers (2.79) (P=0.003). Conclusion. The Endobrush allows the clinician to obtain deeper cells of buccal mucosa. Smokers with clinically normal mucosa show a greater percentage of keratinized cells and a greater nucleolar activity, suggesting that cigarette smoking influences the cellular activity of the mucosa of the lateral tongue

    Endomyocardial fibrosis: a restrictive cardiomyopathy in developing countries

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    Objetivo: La fibrosis endomiocárdica (FE) es una cardiomiopatía restrictiva infrecuente. En América Latina son escasos los reportes. En el presente trabajo se realiza una descripción de una serie de pacientes diagnosticados de FE en Colombia. Método: Realizamos una búsqueda en los registros de imágenes de resonancia magnética (RM) cardiaca realizadas en nuestra institución entre 2016 y 2019 en busca de pacientes con diagnóstico de FE. Se describieron sus características sociodemográficas, clínicas y de imagen. Resultados: Nueve pacientes fueron diagnosticados de FE (el 66.7% mujeres), con una edad promedio de 69 años. Los pacientes presentaron un promedio de 2.6 años de evolución. El principal síntoma referido fue disnea, seguido de síncope, dolor torácico y palpitaciones. En ninguno de ellos se sospechó FE como diagnóstico inicial. En cuanto a los hallazgos ecocardiográficos, se identificó compromiso predominante del ventrículo izquierdo, seguido de compromiso biventricular. Todos los pacientes presentaron patrón de llenado restrictivo con dilatación auricular izquierda severa. En el análisis retrospectivo se cumplieron los criterios de Mocumbi para el diagnóstico de FE en el 100% de los pacientes con gravedad moderada (77.8%). Las imágenes de RM mostraron función sistólica biventricular y volúmenes preservados. Se observó depósito focal de gadolinio subendocárdico a nivel apical y se confirmó la presencia de trombo en el 66% de los casos Conclusión:: La FE es una cardiomiopatía restrictiva infrecuente circunscrita a países tropicales. La mayoría de los pacientes en nuestra serie presentaron compromiso aislado del ventrículo izquierdo, seguido de compromiso biventricular, con función ventricular usualmente preservada.Objective: Endomyocardial fibrosis (EF) is an unusual restrictive cardiomyopathy. In Latin America there are few reports. Here, we made a description of patients diagnosed with EF in Colombia. Method: We conducted a search in the records of cardiac magnetic resonance imaging (MRI) performed in our institution between 2016-2019 looking for patients with a diagnosis of EF; sociodemographic, clinical and imaging characteristics were described. Results: Nine patients were diagnosed with EF (66.7% female), with an average age of 69 years. Patients presented an average evolution of 2.6 years. The main reported symptom was dyspnea, followed by syncope, chest pain, and palpitations. None of them was initially suspected for EF. Regarding echocardiographic findings, predominant left ventricular involvement was identified, followed by bi-ventricular involvement. All the patients presented a restrictive filling pattern with severe left atrial dilation. In a retrospective analysis, Mocumbi criteria for diagnosis of EF were met in 100% of the patients, majority with moderate severity (77.8%). Cardiac MRI showed biventricular systolic function and volumes preserved. Focal subendocardial late gadolinium enhancement was observed on the apex and apical thrombus was confirmed in 66% of the patients Conclusion: FE is an uncommon restrictive cardiomyopathy limited to tropical countries. Most of patients in our series presented isolated involvement of left ventricle, followed by bi-ventricular involvement, with ventricular function usually preserved
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