Implicaciones del filtrado de calidad del índice de vegetación EVI para el seguimiento funcional de ecosistemas

Revista oficial de la Asociación Española de Teledetección[EN] The use of MODIS (Moderate Resolution Imaging Spectroradiometer) images for ecosystem monitoring is currently widespread both in research and management. Vegetation indexes (VIs), such as NDVI (Normalized Difference Vegetation Index) and EVI (Enhanced Vegetation Index), are broadly extended for monitoring ecosystem functioning. These indexes are linear estimators of the fraction of photosynthetically active radiation intercepted by vegetation (fAPAR), the main control of net primary production. However, VIs are subject to errors. To handle such errors, the MOD13Q1 VI product includes a Quality Assessment (QA) layer with information about pixel quality. This QA layer represents a great advantage for final users, allowing filtering of pixels with VI values influenced by aerosols, clouds, snow, or shadows. However, the use of homogeneous filtering criteria throughout a heterogeneous region may cause the systematic loss of information in particular areas or times of the year. In this paper, we assessed the effect of different filtering criteria on spatiotemporal data of EVI for the period 2001-2010 in the Iberian Southeast. Our results showed no effect of filtering on EVI availability and magnitude values in low altitudes, but strong and significant differences in the mountains depending on the filter applied: aerosol, shadows or snow filters. Such effects of filtering on the EVI revealed that monitoring programs in these regions should include a filtering step before exploring for abrupt changes or longterm trends in the EVI time series.[ES] El seguimiento de los ecosistemas con imágenes procedentes del sensor MODIS (Moderate Resolution Imaging Spectroradiometer, espectroradiómetro de imágenes de resolución media) está actualmente muy extendido tanto en tareas de investigación como de gestión. Los índices de vegetación NDVI (Normalized Difference Vegetation Index, índice de vegetación de la diferencia normalizada) y EVI (Enhanced Vegetation Index, índice de vegetación mejorado) son ampliamente usados para la caracterización del funcionamiento ecosistémico. Ambos índices se emplean como estimadores lineales de la fracción de radiación fotosintéticamente activa interceptada por la vegetación (fAPAR), el principal control de la producción primaria. A pesar de sus ventajas, las imágenes de índices de vegetación no están libres de errores. El producto índices de vegetación MOD13Q1 proporciona una capa QA (Quality assessment, evaluación de la calidad) que informa sobre la calidad asociada a cada píxel. Esta información representa una gran ventaja para el usuario, al permitir filtrar aquellos datos que puedan inducir a errores al verse alterados por la presencia de aerosoles, nubes, nieve o sombras. Sin embargo, la realización de un filtrado homogéneo a lo largo de una gran región puede ocasionar la pérdida sistemática de información en determinadas zonas o épocas del año, introduciendo así un sesgo espacial o en la serie temporal. Esta situación puede ser especialmente crítica en regiones con alta heterogeneidad ambiental, como el Sureste Ibérico. En este trabajo evaluamos el efecto que el filtrado de calidad tiene sobre la información espacial y temporal de la base de datos del EVI en el periodo 2001-2010. Los resultados, expresados en porcentaje de información perdida (filtrada) y como efecto de estas pérdidas sobre los valores del EVI, indican que mientras que las áreas de menor altitud no se ven afectadas por el filtrado, las regiones de alta montaña muestran variaciones significativas en sus valores del EVI cuando son filtrados por aerosoles, sombras o la presencia de hielo o nieve. Esto pone de manifiesto la importancia del establecimiento de un protocolo para el procesamiento de la información que considere las características espaciales y temporales de los datos a filtrar.Este trabajo ha sido financiado por el Ministerio de Innovación y Ciencia (Proyecto CGL2010- 22314), la Junta de Andalucía (Proyecto SEGALERT, P09-RNM-5048) y el Centro Andaluz para la Evaluación y Seguimiento del Cambio Global (CAESCG) (Proyecto GLOCHARID).Reyes-Díez, A.; Alcaraz-Segura, D.; Cabello-Piñar, J. (2015). Implications of quality filtering of Enhanced Vegetation Index (EVI) for ecosystem functioning monitoring. Revista de Teledetección. (43):11-30. https://doi.org/10.4995/raet.2015.3316SWORD11304

[Mental disease, existence of diagnostic, use of psychotropic medication: differences by autonomous communities under the national health survey 2006].

BACKGROUND: Most of the studies on psychological distress in Spain have been conducted in small geographical areas or specific population groups. However, there are no studies that provide representative data for each Autonomous Community (AC). The objectives of this paper are to determine, both in Spain and in the AC, the prevalence of psychological distress, diagnosis, use of psychoactive medication, social support and self-perceived health, as well as to study the association between psychological distress and the rest of the variables. METHODS: Cross-sectional study, using data from the 2006 National Health Survey, that was completed by 29,478 persons. VARIABLES STUDIED: sociodemographics, psychological distress (GHQ-12), self-perceived health, mental disorder diagnosis, functional social support (Duke) and use and prescription of psychoactive medication. RESULTS: The prevalence of psychological distress in Spain was 20,1%; the highest prevalence was found in Canary Islands (28,2%) and the lowest in La Rioja (12,2%). Among those who presented psychological distress, 62,4% had never received a mental disorder diagnosis, and 71,6% had not used psychoactive medication in the last year. The highest prevalences of non-diagnosed cases (81,8%) and cases non-treated with psychoactive medication (83,1%) were found in La Rioja, whereas the lowest prevalences were found in Asturias. Eight percent of the persons who presented psychological distress had low social support and 63,8% reported bad self-perceived health. CONCLUSIONS: Psychological distress is a prevalent phenomenon, and more than half of the persons who suffer it receive neither a diagnosis nor psychoactive medication. Moreover, there are considerable differences between the AC

The relationship between reproductive work and sociodemographic and psychosocial factors in regard to psychological distress in men and women in Spain.

Studies have shown that some sociodemographic factors, such as marital status, employment status or social class, can affect mental health in different ways for each gender. However, up until now, few research projects have tried to ascertain if the role that reproductive work or psychosocial factors play in mental health is different for men and women. The aim of this study is to assess the differences between men and women in terms of how reproductive work, sociodemographic and psychosocial factors are linked to psychological distress in Spain. A cross-sectional study of 29,478 male and female adults using data gathered for the Spanish National Health Survey 2006 was carried out. Psychological distress was measured using the GHQ-12. The independent variables analyzed were: sociodemographic, psychosocial (family functionality and functional social support) and those related to reproductive work (living with or being in charge of different types of people needing care and number of hours devoted to caregiver tasks). Different independent logistic regression models were developed for men and women. In general, with the exception of men who were more prone to psychological distress if they were signed off work for 3 months or more, no major differences were observed regarding the effect of sociodemographic and psychosocial characteristics on psychological distress. With regard to reproductive work, the likelihood of psychological distress doubles in both sexes when the person lives with someone who needs care. In women, a greater number of hours devoted to caring for another person is associated with an increase in distress. Men play a less frequent role in caregiving, but the impact on psychological distress is similar to that in women. Women experienced more psychological distress when they had to live with or be in charge of a disabled person or different types of persons needing care, while men were not affected by this. Major differences have been identified in terms of psychological distress in women and men in several aspects of reproductive work to date unexplored