Search results for "Detección"
showing 10 items of 59 documents
The effect of spherical aberration on visual performance and refractive state for stimuli and tasks typical of night viewing
2018
Purpose: The aim of this work was to examine the impact of Seidel spherical aberration (SA) on optimum refractive state for detecting and discriminating small bright lights on a dark background. Methods: An adaptive-optics system was used to correct ocular aberrations of cyclopleged eyes and then systematically introduce five levels of Seidel SA for a 7-mm diameter pupil: 0, ± 0.18, and ± 0.36 diopters (D) mm−2. For each level of SA, subjects were required to detect one or resolve two points of light (0.54 arc min diameter) on a dark background. Refractive error was measured by adjusting stimulus vergence to minimize detection and resolution thresholds. Two other novel focusing tasks for si…
Cálculo de la evapotranspiración real diaria en la zona norte de Finlandia empleando técnicas de teledetección
2005
J. M. Sánchez Tomás (Juan.M.Sanchez@uv.es) Hasta hace poco tiempo el estudio de la evapotranspiración (LE), fundamental en la ecuación de balance de energía, excluía zonas forestales debido a las dificultades experimentales de la toma de medidas en estas regiones. La teledetección acabó con dichas dificultades, facilitando el estudio de la LE real dentro de estas zonas, que suponen en torno a un 30% de toda la superficie terrestre. En este trabajo se presenta un método operativo para determinar la LE real a partir de medidas de temperatura de la superficie realizadas desde satélite. Este estudio se llevó a cabo de abril a junio de 2002 en Sodankylä, una región de bosque boreal en el norte d…
Monitoring water quality and hydrological patterns of wetlands using recent techniques in remote sensing
2017
Los humedales aportan una gran cantidad de servicios ecosistémicos, incluyendo la regulación del ciclo hidrológico para el control de inundaciones y la sequía. También proporcionan suministro de agua, refugios de vida silvestre, y oportunidades de recreación, entre otros. A pesar de que estas áreas tienen un valor fundamental para el desarrollo sostenible, se ven totalmente afectadas por el crecimiento urbano, la extensión de tierras agrícolas y la contaminación derivada de todo ello. La calidad de las aguas y el estado ecológico de los ecosistemas acuáticos se pueden ver deteriorados por el proceso de eutrofización. Éste produce cambios físicos, químicos y biológicos en la masa de agua. Pa…
Monitoring the whiting phenomenon in Lake La Cruz (Cuenca, Spain)
2020
[EN] In the present study, a five-year follow-up was performed by remote sensing of the calcium carbonate precipitation in La Gitana karstic lake also known as La Cruz (located on the province of Cuenca, Spain). The important role that calcium carbonate precipitation plays in the ecology of the lake is well known for its influence on the vertical migrations of phytoplankton, the concentration of bioavailable phosphorus and, therefore, the eutrophication and quality of the waters. Whiting take place between the months of July and August, and it can be studied at this time through its optical properties, with the main objective of offering updated data on a phenomenon traditionally studied an…
Motivos de participación en el Programa de Prevención del Cáncer Colorrectal de la Comunidad Valenciana según sexo, edad y clase social
2014
Objective: To know the reasons to participate or not in a colorectal cancer (CCR) screening programme and to analyze the differences by sex, age and social class. Methods: Cross-sectional study by a telephone survey directed to a sample of men and women aged between 50-74 year old, participants (n = 383) and non participants (n = 383) in the CCR screening programme of Valencian Community. Descriptive analysis and logistic regression models estimating the Odds Ratio (p < 0.05). Results: The main reasons to participate are "it is important for health" (97.9 %) and "the test is easy" (97.6 %); and to non participate are "no CCR symptoms" (49.7 %) and "didn't receive invitation letter" (48.3 %)…
Participación informada en el Programa de Prevención del Cáncer Colorrectal de la Comunidad Valenciana desde una perspectiva de género
2018
Abstract Objective: To examine the factors that influence informed participation in a Colorectal Cancer Screening Programme (CRCSP) from a gender perspective. Methods: Cross-sectional telephone survey directed to men and women invited to participate (2009-2010) in the Valencian Community CRCSP (Spain). Sample size: 785 subjects. Outcome variables: participation in CRCSP and being informed. Bivariate and multivariate analysis using logistic regression models (95% confidence interval [95%CI], p <0.05). Results: Being a woman (odds ratio [OR]: 1.52; 95%CI: 1.06-2.19), receiving information from a general practitioner (OR: 1.64; 95%CI: 1.05-2.55) and being informed (OR: 1.54; 95%CI: 1.08-2.21) …
Clasificación de usos del suelo a partir de imágenes Sentinel-2
2017
[EN] Sentinel-2 (S2), a new ESA satellite for Earth observation, accounts with 13 bands which provide high-quality radiometric images with an excellent spatial resolution (10 and 20 m) ideal for classification purposes. In this paper, two objectives have been addressed: to determine the best classification method for S2, and to quantify its improve-ment with respect to the SPOT operational mission. To do so, four classifiers (LDA, RF, Decision Trees, K-NN) have been selected and applied to two different agricultural areas located in Valencia (Spain) and Buenos Aires (Argentina). All classifiers were tested using, on the one hand, all the S2 bands and, on the other hand, only selecting those…
Development of an Earth observation processing chain for crop biophysical parameters at local and global scale
2017
[ES] Reseña de tesis doctoral defendida el 17 de Julio de 2017. Lugar: Facultat de Física, Universitat de València.
Situación de la investigación en el cribado de cáncer de mama en España: implicaciones para la prevención
2012
ResumenObjetivoLa finalización del despliegue de los programas de detección precoz de cáncer de mama en todas las comunidades autónomas de España ha facilitado el inicio de una investigación conjunta, con información procedente de varios programas, orientada a mejorar su efectividad.MétodosSe ha construido una cohorte de más de 1 millón de mujeres cribadas para evaluar el riesgo y los determinantes de los resultados falsos positivos. Se ha evaluado el impacto del cambio de técnica de mamografía analógica a digital y se está estudiando el cáncer de intervalo y los resultados falsos negativos.ResultadosLos resultados ofrecen información muy útil, desde el punto de vista de salud pública, para…
Development of atmospheric correction algorithms for very high spectral and spatial resolution images: application to SEOSAT and the FLEX/Sentinel-3 …
2018
Advanced high spectral and spatial resolution imager spectrometers on board new generation of Earth Observation missions bring new exciting opportunities to the remote sensing scientific community. However, this progress goes hand in hand with new challenges. The exploitation of data acquired from these family of advanced instruments requires new processing algorithms able to deal with these particularities. As part of this evolution, atmospheric correction algorithms - a mandatory processing step applied prior to the Earth surface reflectance data exploitation - must be adapted or reformulated, thereby paying special attention to how atmospheric effects disturb the acquired signal in the s…