2,661 research outputs found
Enumeration and isolation of viral particles from oligotrophic marine environments by tangential flow filtration
A method for concentrating, enumerating and isolating viral particles from marine water samples was developed and evaluated. The method consists of a concentration step by a tangential flow filtration (TFF) system, ultrafiltration by centrifugal concentrator, and visualization by transmission electron microscopy (TEM). This procedure allows to reduce volumes of ca. 2 l of seawater to 10–20 μl, which can be dispensed on electron microscopy grids to count total viral particles. This method allows the recovery of small numbers of viral particles from oligotrophic seawater samples, in which viral numbers ranged from 105 to 106 viral particles/ml. The tangential flow filtration system was evaluated as quantitative technique using suspensions of two different bacteriophages (T6 and ΦX174) in autoclaved seawater. Recovery rates varied depending on both the viral morphology and flow rate; recovery percentages reached 117.4% for T6 and 60.6% for ΦX174 using low flow rate
Segmentación automática de aneurismas aórticos abdominales a partir de imágenes de resonancia magnética basada en modelos activos de forma y modelos de textura
Se presenta un algoritmo semiautomático de segmentación de aneurismas aórticos abdominales (AAA) basado en modelos activos de forma (ASM) y modelos de textura. La información de textura viene dada por un conjunto de cuatro imágenes 3D de resonancia magnética (RM) compuestas por cortes axiales de la zona abdominal. En estas imágenes son visibles la luz aórtica, la pared aórtica y el trombo intraluminal (ILT). Dado el tamaño limitado del conjunto de imágenes de RM, se han implementado un ASM que capture las caracterÃsticas especÃficas del conjunto de entrenamiento compuesto por 35 imágenes de tomografÃa axial computarizada (CTA), de modo que la variación de forma pueda ser adecuadamente caracterizada. La textura se caracteriza a partir de las imágenes de RM. Para la evaluación del algoritmo se ha llevado a cabo una validación cruzada dejando uno fuera sobre el conjunto de imágenes de RM
Automatic segmentation of abdominal aortic aneurysm from medical images based on active shape models and texture models
A semi-automatic segmentation algorithm for abdominal aortic aneurysms (AAA), and based on Active Shape Models (ASM) and texture models, is presented in this work. The texture information is provided by a set of four 3D magnetic resonance (MR) images, composed of axial slices of the abdomen, where lumen, wall and intraluminal thrombus (ILT) are visible. Due to the reduced number of images in the MRI training set, an ASM and a custom texture model based on border intensity statistics are constructed. For the same reason the shape is characterized from 35-computed tomography angiography (CTA) images set so the shape variations are better represented. For the evaluation, leave-one-out experiments have been held over the four MRI set
La problemática de la empresa familiar ganancial en caso de crisis matrimonial
The present work addresses the problems that derive from the marital crisis, which affects the family business, and which in particular damages spouses who are submitted to the matrimonial property regime of community property.El presente trabajo aborda la problemática que deriva de la crisis matrimonial, que afecta a la empresa familiar, y que en particular damnifica a aquellos cónyuges que se encuentran sometidos al régimen económico matrimonial de gananciales
Pulverized quartz clasts in gouge of the Alhama de Murcia fault (Spain): evidence for coseismic clast pulverization in a matrix deformed by frictional sliding
The fault gouge of the Alhama de Murcia fault (southeast Spain) shows a texture that resembles a mylonite, including a prominent foliation, S-C fabric, and isoclinal folds. It also embeds a large number of isolated pulverized quartz clasts (PQCs). Structural analysis indicates that the gouge fabric was mainly developed by slow frictional sliding along phyllosili- cate-lined Riedel shear bands during continued shearing. In contrast, the PQCs show tensile fracture network features that are typically reported in seismically pulverized rocks found along seismogenic faults. This suggests that quartz-clast pulverization was due to a transient dilatational mechanism rather than shearing. We propose that the PQCs are the result of a rapid confined stress drop related to transient tensile stresses during coseismic ruptures that interrupt creep faulting along the gouge zone. The present study suggests that there is probably a large amount of evidence for paleoseismicity in fault rocks that is currently overlookedThis research was supported by the Spanish Ministry of Economy and Competitiveness under the INTERGEO (CGL2013–47412-C2–1-P) and QUAKESTEP (CGL2017–83931-C3–1-P) project
Park use, perceived park proximity, and neighborhood characteristics: Evidence from 11 cities in Latin America
This study examines how park use may be associated with perceived park proximity, neighborhood-built environment and perceived social disorder in Latin American cities. The study uses self-reported data from the 2016 CAF survey, including 7,970 urban residents from 11 cities across Latin America. Results show positive graded associations between perceived park proximity and use, holding all others constant. Additional factors that were found to be associated with park use are neighborhood formality and related built-environment characteristics, including paved streets and sidewalks. Park use was mostly unrelated to perceived social disorder, with the exception of indigence, with which it is was positively associated. Stronger associations between park proximity and use were observed among those who reported higher prevalence of indigence or begging in their household block. These findings stress the importance of perceived park proximity in enhancing their use in urban Latin America, and challenge the role of social disorder and crime as a barrier for park use
Segmentación de la Luz Aórtica en Imágenes de Resonancia Magnética para Guiado de Catéteres Aórticos
Los procedimientos de cateterismo se han convertido en una herramienta fundamental para las intervenciones cardiovasculares. El proyecto SCATh pretende facilitar el guiado del catéter a partir de un modelo preoperatorio del paciente basado en imágenes 3D, para lo que se requiere la segmentación de la luz y la pared aórtica. Aunque la mayorÃa de los centros hacen uso de CTA, está estudiándose el uso de imágenes de RM para este fin, puesto que puede permitir la segmentación de la luz y la pared aórtica sin el uso de agentes de contraste nefrotóxicos. Se ha implementado un método de segmentación de la luz de la aorta en imágenes de RM sin agentes de contraste basado en el uso de un algoritmo de realzado de estructuras vasculare
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