Local likelihood estimation of complex tail dependence structures, applied to U.S. precipitation extremes

To disentangle the complex non-stationary dependence structure of precipitation extremes over the entire contiguous U.S., we propose a flexible local approach based on factor copula models. Our sub-asymptotic spatial modeling framework yields non-trivial tail dependence structures, with a weakening dependence strength as events become more extreme, a feature commonly observed with precipitation data but not accounted for in classical asymptotic extreme-value models. To estimate the local extremal behavior, we fit the proposed model in small regional neighborhoods to high threshold exceedances, under the assumption of local stationarity, which allows us to gain in flexibility. Adopting a local censored likelihood approach, inference is made on a fine spatial grid, and local estimation is performed by taking advantage of distributed computing resources and the embarrassingly parallel nature of this estimation procedure. The local model is efficiently fitted at all grid points, and uncertainty is measured using a block bootstrap procedure. An extensive simulation study shows that our approach can adequately capture complex, non-stationary dependencies, while our study of U.S. winter precipitation data reveals interesting differences in local tail structures over space, which has important implications on regional risk assessment of extreme precipitation events

A spliced Gamma-Generalized Pareto model for short-term extreme wind speed probabilistic forecasting

Renewable sources of energy such as wind power have become a sustainable alternative to fossil fuel-based energy. However, the uncertainty and fluctuation of the wind speed derived from its intermittent nature bring a great threat to the wind power production stability, and to the wind turbines themselves. Lately, much work has been done on developing models to forecast average wind speed values, yet surprisingly little has focused on proposing models to accurately forecast extreme wind speeds, which can damage the turbines. In this work, we develop a flexible spliced Gamma-Generalized Pareto model to forecast extreme and non-extreme wind speeds simultaneously. Our model belongs to the class of latent Gaussian models, for which inference is conveniently performed based on the integrated nested Laplace approximation method. Considering a flexible additive regression structure, we propose two models for the latent linear predictor to capture the spatio-temporal dynamics of wind speeds. Our models are fast to fit and can describe both the bulk and the tail of the wind speed distribution while producing short-term extreme and non-extreme wind speed probabilistic forecasts.Comment: 25 page

Drug Trafficking and the Presidential Family in Venezuela: The Narco Nephews

An explosive combination of political turmoil, a deep economic crisis and critical security situation has Venezuela on the verge of collapse. Despite the alarming situation in the country, not everyone is doing so bad, especially those close to the ruling power. Ferraris, access to private aircrafts and bodyguards are only some of the privileges that only few can get access to in this impoverished South American nation. Efrain Antonio Campo Flores, 30, and Franqui Francisco Flores de Freitas, 31 -- the nephews of the Venezuelan Presidential couple -- were found guilty of conspiring to import hundreds of kilograms of cocaine into the U.S. https://medium.com/@danielacastroromero/drug-trafficking-and-the-presidential-family-in-venezuela-15e099a7fbb4#.3waxzqgz

Cambios placentarios asociados a patología vascular hipertensiva materna y su correlación clínica en hospital público de la ciudad de Quito en el período comprendido entre Enero del 2014 a Julio del 2015

Introduction: Hypertensive disorders of pregnancy after 20 weeks of gestation can be classified as: Gestational hypertension, preeclampsia, preeclampsia with signs of severity, eclampsia and HELLP syndrome. In our country the main cause of maternal mortality is the obstetric causes, where eclampsia was found with a mortality rate of 5.33 per 100,000 live births and gestational hypertension with significant proteinuria with a ratio of 3.55 Per 100,000 live births. Vascular changes are important in understanding the pathophysiology of these disorders, despite the pathogenesis that has not been fully explained at present. Objective: To identify the macroscopic and microscopic placental vascular changes that may have the hypertensive disorders of pregnancy on the placenta and to correlate these with clinical aspects of the patients with maternal hypertensive vascular disease. Materials and methods: During the year 2014 until the first semester of 2015, a total of 512 placentas were analyzed in the Laboratory of Histopathology of the Gynecological Obstetrical Hospital Isidro Ayora (HGOIA). Of these, 87 placentas or 17% (95% CI 13.8 to 20.5) presented the clinical diagnosis of hypertensive disorders of pregnancy (THE), such as: Gestational hypertension, preeclampsia, preeclampsia with signs of severity, eclampsia And HELLP syndrome. The analysis of this thesis was performed in a sample of 87 patients with clinical diagnosis of THE in whom macroscopic and microscopic placenta data were available. Results: This study showed that there are statistically significant differences between: the average weight of placentas and the different hypertensive disorders of pregnancy (P value = 0.03). Second, gestational age was statistically higher in patients with preeclampsia compared to patients with preeclampsia with signs of severity (35.1 weeks vs 32.9 weeks, P value = 0.03). Third, mean placental weight was greater in patients with preeclampsia than in patients with preeclampsia with signs of severity (362 grams vs 292 grams, P value = 0.05). In addition, a higher frequency of placental macroscopic infarction was observed in patients with preeclampsia (77.50%) compared to patients with preeclampsia with signs of severity (52%) P value = 0.05.Introducción: Los trastornos hipertensivos del embarazo (THE) pasadas las 20 semanas de gestación, se pueden clasificar en: Hipertensión gestacional, preeclampsia, preeclampsia con signos de severidad, eclampsia y Síndrome de HELLP. En nuestro país la principal causa de mortalidad materna son las causas obstétricas, dentro de las cuales se ubicó a la eclampsia con una razón de mortalidad de 5,33 por 100.000 nacidos vivos y la hipertensión gestacional con proteinuria significativa con una razón de 3,55 por 100.000 nacidos vivos. Los cambios vasculares son importantes en el entendimiento de la fisiopatología de estos trastornos, pese a la etiopatogenia que no ha sido esclarecida totalmente en la actualidad. Objetivo: Identificar los cambios vasculares placentarios macroscópicos y microscópicos que pueden tener los trastornos hipertensivos del embarazo sobre la placenta y correlacionar éstos con aspectos clínicos de las pacientes con patología vascular hipertensiva materna. Materiales y métodos: Durante el año 2014 hasta el primer semestre del año 2015, un total de 512 placentas fueron analizadas en el Laboratorio de Histopatología del Hospital Gineco Obstétrico Isidro Ayora (HGOIA). De éstas, 87 placentas es decir 17% (IC de 95% 13,8 a 20,5) presentaron el diagnóstico clínico de trastornos hipertensivos del embarazo (THE), tales como: Hipertensión gestacional, preeclampsia, preeclampsia con signos de severidad, eclampsia y Síndrome de HELLP. El análisis de esta tesis fue realizado en una muestra de 87 pacientes con diagnóstico clínico de THE en quienes, los datos macroscópicos y microscópicos de placentas estuvieron disponibles. Resultados: Este estudio demostró que existen diferencias estadísticamente significativas entre: el peso promedio de las placentas y los diferentes trastornos hipertensivos del embarazo (valor P=0,03). Segundo, la edad gestacional fue estadísticamente mayor en las pacientes con preeclampsia comparada con pacientes con preeclampsia con signos de severidad (35.1 semanas vs 32.9 semanas, valor P=0,03). Tercero, el peso placentario promedio fue mayor en pacientes con preeclampsia que en pacientes con preeclampsia con signos de severidad (362 gramos vs 292 gramos, valor P=0,05). Además se observó mayor frecuencia de infarto macroscópico placentario en las pacientes con diagnóstico de preeclampsia (77,50%) en relación a las pacientes con diagnóstico de preeclampsia con signos de severidad (52%) Valor P=0,05

Textures and composition of hydrothermal tourmaline in the Chacaltaya-Kellhuani-Milluni district, La Paz, Bolivia

Los minerales pertenecientes al supergrupo de la turmalina son muy útiles para registrar las condiciones fisicoquímicas de su cristalización y rastrear los procesos geológicos asociados a la formación de depósitos minerales. Este estudio presenta nuevos resultados sobre la petrografía y geoquímica de turmalina en el distrito Triásico de Chacaltaya-Kellhuani-Milluni (oeste de Bolivia), ubicado en el segmento norte de la Cordillera Real dentro del Cinturón Estannífero de los Andes Centrales. El área de estudio se encuentra alrededor del stock granítico de Chacaltaya, aproximadamente 5 km al sur del granito de Huayna-Potosí. En este distrito, la mineralización hidrotermal está asociada a greisen, brechas y vetas. Se distinguen tres tipos principales de turmalina hidrotermal, de acuerdo a la petrografía: i) Tur-1, que presenta un color naranja y se manifiesta como cristales esqueléticos dispersos o como reemplazamiento pseudomórfico de cristales primarios de feldespato potásico en el granito greisenizado de Chacaltaya, como cristales euhedrales a subhedrales diseminados que a menudo forman agregados radiales en el greisen, y como fragmentos de cristales en brechas cementadas por turmalina; ii) Tur-2, que se presenta como cristales aciculares muy finos de color verde oscuro que componen el cemento de las brechas; y iii) Tur-3, que forma cristales elongados subhedrales de color verde con tonalidades marrones con zonación oscilatoria dentro de las vetas y cristales anhedrales muy finos en el halo de las vetas. Tanto Tur-2 como Tur-3 muestran evidencia textural de co-cristalización con casiterita tanto en brechas hidrotermales como en vetas. Los tres tipos petrográficos pertenecen al grupo de las turmalinas alcalinas y se caracterizan por ser ricas en Fe, en su mayoría cercanas a la composición del chorlo, extendiéndose en parte a los campos composicionales de la foitita y dravita. La superposición composicional de los tres tipos petrográficos de turmalina sugiere un continuo en la evolución del fluido hidrotermal que reflejaría un enfriamiento progresivo del sistema desde Tur-1 a Tur3, lo que finalmente habría conducido a la cristalización de casiterita coetáneamente a la cristalización de Tur-2 y Tur-3.Minerals of the tourmaline supergroup are useful to decipher the physicochemical conditions of its crystallization and to trace geologic processes associated with the formation of ore deposits. This study presents new results on the petrography and geochemistry of tourmaline from the Triassic Chacaltaya-Kellhuani-Milluni district (western Bolivia), located in the northern segment of the Cordillera Real within the Central Andean tin belt. The study area lies around the Chacaltaya granitic stock about 5 km south of the Huayna-Potosí granite. Here, hydrothermal mineralization is associated with greisen, breccia, and veins. Three main petrographic types of hydrothermal tourmaline are distinguished: i) Tur-1, which is orange in color and occurs as scattered skeletal crystals or pseudomorphic replacement of primary Kfeldspar in the greisenized Chacaltaya granite, as disseminated euhedral to subhedral crystals mostly forming radial aggregates in greisen, and as crystal fragments in tourmaline-cemented breccias; ii) Tur-2, which appears as very fine acicular grains with a dark-green color composing the cement of breccias; and iii) Tur-3, which forms elongated green-brownish subhedral, oscillatory-zoned crystals within veins, and anhedral, very fine-grained crystals in the halos of veins. Both Tur-2 and Tur-3 show textural evidence of co-crystallization with cassiterite in both hydrothermal breccias and veins. The three petrographic types of tourmaline belong to the alkali group and are characterized by Fe-rich compositions, in majority close to the schorl endmember, and partly extending into the compositional fields of foitite and dravite. Overlapping tourmaline compositions suggest a progressive cooling of the ore-forming system from Tur-1 to Tur-3, eventually leading to cassiterite deposition during the crystallization of Tur-2 and Tur-3

Incremental Sampling-based Algorithm for Minimum-violation Motion Planning

This paper studies the problem of control strategy synthesis for dynamical systems with differential constraints to fulfill a given reachability goal while satisfying a set of safety rules. Particular attention is devoted to goals that become feasible only if a subset of the safety rules are violated. The proposed algorithm computes a control law, that minimizes the level of unsafety while the desired goal is guaranteed to be reached. This problem is motivated by an autonomous car navigating an urban environment while following rules of the road such as "always travel in right lane'' and "do not change lanes frequently''. Ideas behind sampling based motion-planning algorithms, such as Probabilistic Road Maps (PRMs) and Rapidly-exploring Random Trees (RRTs), are employed to incrementally construct a finite concretization of the dynamics as a durational Kripke structure. In conjunction with this, a weighted finite automaton that captures the safety rules is used in order to find an optimal trajectory that minimizes the violation of safety rules. We prove that the proposed algorithm guarantees asymptotic optimality, i.e., almost-sure convergence to optimal solutions. We present results of simulation experiments and an implementation on an autonomous urban mobility-on-demand system.Comment: 8 pages, final version submitted to CDC '1

Identificación en línea y optimización del péndulo invertido implementado con el Lego Mindstorm NXT 2.0 utilizando la técnica de control LQR

El control, la automatización y la robótica se han convertido durante las últimas décadas en áreas primordiales en la investigación y el desarrollo de nuevas tecnologías. Hoy en día existen varias investigaciones acerca de la optimización de sistemas físicos usando diferentes técnicas, Un problema típico abordado por la teoría de control es el péndulo invertido, este es un sistema clásico que se caracteriza principalmente por su comportamiento inestable. El modelo de este sistema es de gran aplicación en la vida cotidiana principalmente en la industria, y es muy utilizado como ejercicio académico. Seleccionando este sistema físico y aprovechando la posibilidad de implementarlo físicamente con en el equipo LEGO Mindstorm NXT 2.0.se propone aplicar dos técnicas muy importantes como lo son: la identificación en línea de un modelo digital del péndulo invertido y el control optimo LQR (“Linear Quadratic Regulator”) del mismo

Avaliação nasométrica de crianças surdas

Mestrado em Ciências da Fala e da AudiçãoO presente trabalho teve como principal objectivo testar a aplicabilidade clínica do Nasómetro em crianças com surdez. Mais concretamente, foram avaliadas as diferenças entre crianças normo-ouvintes e crianças surdas ao nível da ressonância nasal. Para além disso, foi estudado o efeito da utilização de diferentes tecnologias de apoio (prótese auditiva vs. implante coclear) e de diferentes estímulos de fala (sílabas, palavras e frases) nos valores de nasalância. Tendo em conta as especificidades do Português Europeu, no que respeita à nasalidade, foram criados três sub-testes: repetição de sílabas, nomeação de imagens e leitura de frases. A escolha dos estímulos obedeceu a critérios de ausência ou saturação de segmentos nasais. Foram recolhidos dados de 22 crianças normo-ouvintes e de 14 crianças surdas (7 beneficiárias de prótese auditiva e 7 com implante coclear), usando o Nasómetro. Os resultados evidenciaram diferenças significativas entre o grupo normoouvinte e o grupo com implante coclear para todos os estímulos orais, o que sugere uma tendência para a hipernasalidade. Para além disso, não se verificaram diferenças entre o grupo com prótese auditiva e o grupo normoouvinte em nenhum dos estímulos testados. Os resultados obtidos evidenciaram ainda uma grande variabilidade inter-sujeitos, principalmente no grupo com implante coclear. Relativamente às diferenças entre estímulos, as sílabas, quando comparadas com as frases e as imagens, apresentaram valores de nasalância superiores. Os valores de nasalância obtidos pelo grupo normo-ouvinte seguiram o mesmo padrão de nasalância de outros estudos de nasometria para o português europeu. O Nasómetro poderá ser útil como medida de avaliação nasométrica em crianças normo-ouvintes e surdas, complementando a avaliação auditivoperceptiva da ressonância nasal.This work had as its main goal to test the nasometer clinical application in deaf children. I have ensued an evaluation of the differences on nasal resonance among children with normal hearing and deaf children. Moreover, it was studied the effect of using different support technologies (hearing aid vs cochlear implant) and different speach stimuli (syllable, words and sentences) regarding the nasalance scores. Considering the specificity of the European Portuguese language regarding nasalance three sub-tests were used: syllable repetition, naming images and reading sentences. The stimuli choice complied with criterion of lacking or saturation of nasal segments. The collection of data of 22 normal hearing children and 14 deaf children (7 children with hearing aid and 7 with cochlear implant) by using a nasometer. The results are a clear evidence of the significant differences between the normal hearing children group and the ones with cochlear implants (regarding all oral speech stimuli). This fact suggests a predisposition to hipernasality. Furthermore, there are no other differences between the group using hearing aid and the one with normal hearing. The results achieved are also an indication of a huge intersubject variability, mainly among children with cochlear implants. Regarding the differences between the stimuli used, when syllables are compared to sentences and to images, they offer superior nasalance scores. Nasalance scores obtained from children with normal hearing have followed the same nasalance pattern found in other nasometry studies for the European Portuguese language. The Nasometer can be useful as a measure for nasometric evaluation of deaf children and of children with normal hearing. This will enhance the perceptive auditive results

Desenvolvimento de um Índice de Qualidade da Dieta Adaptado para Gestantes

OBJETIVO: Desenvolver um Índice de Qualidade da Dieta Adaptado para Gestantes (IQDAG) e avaliar sua relação com características de mulheres atendidas pelo Sistema Único de Saúde. MÉTODOS: Os dados de consumo alimentar são provenientes de um estudo transversal conduzido entre 785 gestantes adultas do município de Ribeirão Preto, SP, entre 2011 e 2012. A elaboração do índice foi baseada nas recomendações do Ministério da Saúde, em índices dietéticos nacionais prévios e no novo Guia Alimentar para a População Brasileira. Para descrever a qualidade da dieta segundo as características maternas, foram empregados os testes ANOVA, Kruskal-Wallis e qui-quadrado. RESULTADOS: O IQDAG apresenta nove componentes, sendo representados por três grupos de alimentos (em porções/1.000 kcal); cinco nutrientes; e um componente moderador. Elevada proporção de gestantes atingiu a pontuação máxima para os componentes leguminosas e hortaliças. Porém, poucas mulheres atingiram a pontuação máxima para o consumo de frutas frescas, ingestão de fibras, ômega 3, cálcio, folato, ferro e alimentos ultraprocessados. Verificou-se melhor qualidade da dieta entre gestantes de maior idade, eutróficas, que relataram praticar mais tempo de atividade física e que faziam uso de suplementos dietéticos. A maior pontuação do índice também foi observada entre as mulheres com maior ingestão de carboidratos, proteínas, vitaminas C, E e A, e dos minerais cálcio, folato e ferro, bem como entre aquelas com menor ingestão de gorduras totais e gorduras saturadas. CONCLUSÕES: O presente índice dietético foi inédito ao incorporar a recomendação do novo Guia Alimentar para a População Brasileira quanto à moderação do consumo de alimentos ultraprocessados. Demonstrou-se útil na avaliação da qualidade da dieta de gestantes e uma maior pontuação foi verificada entre mulheres de maior idade, eutróficas e que relataram um estilo de vida saudável. Estratégias de promoção do consumo de frutas frescas, alimentos ricos em fibras, ômega 3, cálcio, folato, ferro e minimamente processados em gestantes são necessárias.OBJECTIVE: To develop a Diet Quality Index Adapted for Pregnant Women (IQDAG) and to evaluate its relation with the characteristics of women treated at the Brazilian Unified Health System. METHODS: The data on food intake come from a cross-sectional study carried out with 785 adult pregnant women in the city of Ribeirão Preto, state of São Paulo, Brazil, between 2011 and 2012. The index was based on the recommendations of the Brazilian Ministry of Health, previous national dietary indexes, and the new Dietary Guidelines for the Brazilian Population. We used the ANOVA, Kruskal-Wallis, and chi-square tests to describe the quality of the diet according to the characteristics of the mother. RESULTS: The IQDAG has nine components, and it is represented by three food groups (in servings/1,000 kcal), five nutrients, and a moderator component. A high proportion of pregnant women reached the maximum score for the components of legumes and vegetables. However, few women reached the maximum score for consumption of fresh fruits, fiber, omega-3, calcium, folate, iron, and ultra-processed foods. We verified a better quality of diet among older and eutrophic pregnant women who reported practicing more physical activity and taking dietary supplements. We also observed the highest index score among women with higher intake of carbohydrates, proteins, vitamins C, E, and A, and minerals calcium, folate, and iron, as well as among those with lower intake of total fats and saturated fats. CONCLUSIONS: This dietary index is unprecedented in incorporating the recommendation of the new Dietary Guidelines for the Brazilian Population regarding the moderation of the consumption of ultra-processed foods. It was useful in evaluating the quality of the diet of pregnant women and we verified a higher score among older and eutrophic women who reported a healthy lifestyle. Strategies are needed to promote a higher consumption of fresh fruits, foods high in fiber, omega-3, calcium, folate, iron, and minimally processed foods in pregnant women

Perceived neighbourhood quality and adult health status: new statistical advices useful to answer old questions?

Interest in the quantitative effects of neighbourhood characteristics on adult health has recently increased in social epidemiology. Particularly, investigations concern the statistical influence on health of several individual demographic and socioeconomic characteristics and of neighbourhood characteristics as perceived by respondents. We analyze these issues within an original conceptual framework and employing statistical models unusual in this context. We use data collected in the Los Angeles Family and Neighbourhood Survey (L.A.FANS) to model the number of hospital admissions occurred to each individual as a function of some individual and neighbourhood characteristics, the latter being related to the individual perceptions about the neighbourhood he lives in. We employ generalized additive models with different distributional assumptions: Poisson, Negative Biomial and Zero Inflated Poisson (ZIP). Such models allow us to estimate (through spline functions) potential non linear effects of the covariates on the response. Moreover, non standard representations are used to overcome difficulties in interpreting the results for ZIP models. It turns out that perceived neighbourhood characteristics, and in particular the perception of social cohesion, have a significant effect after controlling for individual characteristics relevant to hospital admissions frequency. From a modeling point of view ZIP and Negative binomial models prove to be superior to standard Poisson model. We have confirmed the role of the neighbourhood where an individual lives in determining his health status. A strength of this analysis is that, due to the choice of the neighbourhood characteristics to be included in the model, the results do not depend of a particular definition of neighbourhood (which is traditionally based on administrative boundaries), since each individual refers his perceptions to his personal definition of it