1,477 research outputs found
La arteriografía selectiva de las ramas de la aorta abdominal
Es unánime el consenso acerca de la dificultad que implica llegar al diagnóstico de enfermedades de los aparatos digestivo y urinario. Si bien es cierto que el empleo de la radiografía, especialmente desde la introducción de las técnicas de contraste, significó un gran avance, no es menos evidente que su mayor importancia actual radica en el hecho de ser punto de partida para el descubrimiento de nuevos y cada día más precisos métodos de diagnóstico, que sin embargo tienen sus limitaciones, contraindicaciones, complicaciones y riesgos
Simulation-based model course to demonstrate seafarers' competence for deck officers' discipline
Postprint (published version
Contribution of isotopic research techniques to characterize highmountain-Mediterranean karst aquifers: The Port del Comte (Eastern Pyrenees) aquifer.
Water resources in high mountain karst aquifers are usually characterized by high rainfall, recharge and discharge that leads to the sustainability of the downstream ecosystems. Nevertheless, these hydrological systems are vulnerable to the global change impact. The mean transit time (MTT) is a key parameter to describe the behavior of these hydrologic systems and also to assess their vulnerability. This work is focused on estimating MTT by using water stable isotopes in the framework of high-mountain karst systems with a very thick unsaturated zone (USZ). To this end, it is adapted to alpine zones an existing methodology that combines in a row a semi-distributed rainfall-runoff model used to estimate recharge time series, and a lumped-parameter model to obtain through a convolution integral. The methodology has been applied to the Port del Comte Massif (PCM) hydrological system (Southeastern Pyrenees, NE Spain), a karst aquifer system with an overlying1000 m thick USZ. Six catchment areas corresponding to most important springs of the system are considered. The obtained results show that hydrologically the behavior of the system can be described by an exponential flow model (EM), with MTT ranging between 1.9 and 2.9 years. These values are shorter than those obtained by considering a constant recharge rate along time, which is the easiest and most applied aquifer recharge hypothesis when estimating through lumped-parameter models. This methodology can be useful to improve the characterization and understanding of other high mountain karst aquifers with an overlying thick USZ that are common in many alpine zones elsewhere the globe
Engineering estructural defense responses in tomato for resistance against the bacterial wilt
Trabajo presentado en 5th International Symposium on Plant Apoplastic Diffusion Barriers (PADiBA) celebrado en Dundee (Escocia) del 13 al 15 de septiembre de 2022
Catastrophic overfitting can be induced with discriminative non-robust features
Adversarial training (AT) is the de facto method for building robust neural
networks, but it can be computationally expensive. To mitigate this, fast
single-step attacks can be used, but this may lead to catastrophic overfitting
(CO). This phenomenon appears when networks gain non-trivial robustness during
the first stages of AT, but then reach a breaking point where they become
vulnerable in just a few iterations. The mechanisms that lead to this failure
mode are still poorly understood. In this work, we study the onset of CO in
single-step AT methods through controlled modifications of typical datasets of
natural images. In particular, we show that CO can be induced at much smaller
values than it was observed before just by injecting images with
seemingly innocuous features. These features aid non-robust classification but
are not enough to achieve robustness on their own. Through extensive
experiments we analyze this novel phenomenon and discover that the presence of
these easy features induces a learning shortcut that leads to CO. Our findings
provide new insights into the mechanisms of CO and improve our understanding of
the dynamics of AT. The code to reproduce our experiments can be found at
https://github.com/gortizji/co_features.Comment: Published in Transactions on Machine Learning Research (TMLR
Edge detection algorithm based on fuzzy logic theory for a local vision system of robocup humanoid league
Este artículo presenta el desarrollo de un algoritmo para la extracción de bordes basado en la teoría de lógica difusa, mediante el cual es posible reconocer las marcas de un campo de juego para la liga humanoide de RoboCup. El algoritmo propuesto describe la creación de un sistema de inferencia difuso que permite evaluar la relación existente entre los pixeles de una imagen, encontrando así las variaciones en los niveles de gris para una vecindad de pixeles específica. Posteriormente se plantea la implementación del método OTSU para binarizar la imagen obtenida en el proceso difuso y así generar una imagen que contiene solo los bordes extraídos, validando el algoritmo en imágenes de la liga humanoide. Luego se analizan los resultados obtenidos evidenciando el buen desempeño del algoritmo, considerando que el tiempo de procesamiento de la propuesta es tan solo el 35% más del tiempo necesario en métodos tradicionales, mientras que los bordes extraídos son unos 52% menos susceptibles al ruido.At this paper we shown the development of an algorithm to perform edges extraction based on fuzzy logic theory. This method allows recognizing landmarks on the game field for Humanoid League of RoboCup. The proposed algorithm describes the creation of a fuzzy inference system that permit evaluate the existent relationship between image pixels, finding variations on grey levels of related neighbor pixels. Subsequently, it shows an implementation of OTSU method to binarize an image that was obtained from fuzzy process and so generate an imagecontaining only extracted edges, validating the algorithm with Humanoid League images. Later, we analyze obtained results that evidence a good performance of algorithm, considering that this proposal only takes an extra 35% processing time that will be required by traditional methods, whereas extracted edges are 52% less noise susceptible
Quantitative study of hydration of C3S and C2S by thermal analysis. Evolution and composition of C-S-H gels formed
This research is part of a European project (namely, CODICE project), main objective of which is modelling, at a multi-scale, the evolution of the mechanical performance of non-degraded and degraded cementitious matrices. For that, a series of experiments were planned with pure synthetic tri-calcium silicate (C3S) and bi-calcium silicate (C2S) (main components of the Portland cement clinker) to obtain different calcium–silicate–hydrate (C–S–H) gel structures during their hydration. The characterization of those C–S–H gels and matrices will provide experimental parameters for the validation of the multi-scale modelling scheme proposed. In this article, a quantitative method, based on thermal analyses, has been used for the determination of the chemical composition of the C–S–H gel together with the degree of hydration and quantitative evolution of all the components of the pastes. Besides, the microstructure and type of silicate tetrahedron and mean chain length (MCL) were studied by scanning electron microscopy (SEM) and 29Si magic-angle-spinning (MAS) NMR, respectively. The main results showed that the chemical compositions for the C–S–H gels have a CaO/SiO2 M ratio almost constant of 1.7 for both C3S and C2S compounds. Small differences were found in the gel water content: the H2O/SiO2 M ratio ranged from 2.9 ± 0.2 to 2.6 ± 0.2 for the C3S (decrease) and from 2.4 ± 0.2 to 3.2 ± 0.2 for the C2S (increase). The MCL values of the C–S–H gels, determined from 29Si MAS NMR, were 3.5 and 4 silicate tetrahedron, for the hydrated C3S and C2S, respectively, remaining almost constant at all hydration periods
Evaluación del efecto de la concentración de sustrato como fuente de nitrógeno y el inóculo en la producción de pleurotus ostreatus
Uno de los hongos comestibles más estudiado y cultivado durante los últimos años es el Pleurotus ostreatus debido a la facilidad de cultivo y a su calidad nutricional. El objetivo de este trabajo fue evaluar crecimiento y la producción Pleurotus ostreatus con el fin de establecer las condiciones óptimas respecto al inóculo y sustrato, para esto se utilizó la metodología de superficie de respuesta para evaluar los efectos del porcentaje de inóculo variándolo entre el 3 y 9%, y porcentaje de la fuente de nitrógeno variándolo entre el 20 y 40%, se prepararon 11 tratamientos para realizar las corridas del diseño experimental, como fuente de nitrógeno se utilizó salvado de trigo, como fuente de carbono se utilizó aserrín, los tratamientos fueron incubados en una cámara climática a 28°C y 65% de humedad por 46 días. Después del periodo de incubación se observó el crecimiento micelial en las bolsas de cada tratamiento este se calificó de 1 a 5 siendo 1 el de menor crecimiento y 5 el de mayor. Los tratamientos con mayor crecimiento de micelio en los sustratos fueron los que tenían una composición de 30% de fuente de nitrógeno y un 6% de inóculo. En la superficie de respuesta se observó que el porcentaje óptimo de inóculo esta alrededor del 5% y el de fuente de nitrógeno alrededor del 25%. Para un cultivo adecuado del Pleurotus o, se deben manejar adecuadamente las condiciones de temperatura, humedad y luz y un manejo aséptico para evitar el crecimiento de otros organismos que compitan por el sustrato
African dust influence on ambient PM levels in South-Western Europe (Spain and Portugal): a quantitative approach to support implementation of Air Quality Directives
This manuscript proposes and validates a methodology for the quantification of the daily African PM load during dust outbreaks in southern Europe. The daily net dust load in PM10 attributable to an African episode can be obtained by subtracting the daily regional background (RB) level from the PM10 concentration value at a RB station. The daily RB level can be obtained by applying a monthly moving 30th percentile to the PM10 time series at a RB station after a prior extraction of the data coincident with African dust transport. For days with influence of African dust, the dust load is given by the difference between the daily PM10 values minus the daily PM10 RB levels. This method allows us to quantify the net African dust load without chemical speciation. The comparison between the estimated net load during African dust outbreaks (ADO) and the crustal load determined by chemical speciation of PM10 filters at three RB stations in Spain had resulted in a very good correlation (R2=0.60-0.83), being the equivalence (correlation lines’ slopes ~ 1) highly significant in the three cases.This study was supported by the S.G.D. Environmental Quality and Industrial Environment from the Spanish Ministry of the Environment, but also by research projects from the Ministry of Science and Innovation (CGL2005-03428- C04-03/CLI, CGL2007-62505/CLI, GRACCIE- CSD2007-00067), the European Union (6th framework CIRCE IP, 036961, EUSAAR RII3-CT-2006-026140) and the Ministry of the Environment (CALIOPE, 441/2006/3-12.1)
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