Evaluación de Imágenes Modis para el Monitoreo de La Deforestación en México / Evaluation of Modis Images to Monitor Deforestation in Mexico

Se evaluaron diferentes productos derivados de imágenes del sensor MODIS y métodos de detección de cambio para la determinación de áreas deforestadas en dos regiones de México. Los datos MODIS utilizados fueron el mapa de cambio de vegetación (MOD44A) y los índices de vegetación (MOD13). Los métodos de detección de cambio fueron una clasificación multifecha, una comparación post-clasificatoria y técnicas de realce como El vector de cambio, la diferencia de imagen y el análisis en componentes principales selectiva (ACPS). Las dos versiones del producto MOD44A que se evaluaron no indicaron ningún cambio para ambas áreas de estudio, ES decir que no detectaron ninguna de las áreas deforestadas aunque algunas de ellas alcanzaban superficies importantes (> 100 ha). Los métodos de realce de imagen permitieron generar mapas de cambio que presentan una fiabilidad satisfactoria

Una comparación de diferentes enfoques de modelación de cambios de cobertura/uso del suelo

International audienceDurante las últimas décadas, una gran variedad de modelos fueron desarrollados para predecir la localización de los CUCS. En este estudio, se comparan cuatro programas de modelación: CLUE, DINAMICA EGO, CA_Markov and Land Change Modeler (ambos disponible en IDRISI). En un primer paso, se revisaron los diferentes métodos y herramientas disponibles en cada modelo para llevar a cabo los diferentes pasos de la modelación (estimación de la cantidad de cambio, relación entre las variables explicativas y los cambios, alocación de los cambios, reproducción de los patrones espaciales, evaluación del desempeño del modelo, posibilidad de desarrollar modelos más sofisticados). En un paso siguiente, se aplicaron los modelos a un caso de estudio virtual, basado en un escenario de deforestación sencillo. Esta estrategia nos permitió comparar los modelos en situaciones controladas y desarrollar situaciones retadoras para evaluar el desempeño de cada modelo. Se compararon los diferentes productos de la modelación (mapas de probabilidad de cambio, mapas de coberturas simulados) y se evaluaron los modelos tomando en cuanto su flexibilidad y capacidad para llevar a cabo las diferentes tareas relacionadas con la modelación

Evaluación de Imágenes Modis para el Monitoreo de la Deforestación en MéxicoEvaluation of Modis Images to Monitor Deforestation in Mexico

Se evaluaron diferentes productos derivados de imágenes del sensor MODIS y métodos de detección de cambio para la determinación de áreas deforestadas en dos regiones de México. Los datos MODIS utilizados fueron el mapa de cambio de vegetación (MOD44A) y los índices de vegetación (MOD13). Los métodos de detección de cambio fueron una clasificación multifecha, una comparación post-clasificatoria y técnicas de realce como el vector de cambio, la diferencia de imagen y el análisis en componentes principales selectiva (ACPS). Las dos versiones del producto MOD44A que se evaluaron no indicaron ningún cambio para ambas áreas de estudio, es decir que no detectaron ninguna de las áreas deforestadas aunque algunas de ellas alcanzaban superficies importantes (> 100 ha). Los métodos de realce de imagen permitieron generar mapas de cambio que presentan una fiabilidad satisfactoria.Abstract The performance of different products derived from sensor MODIS imagery and change detection methods in detecting deforested areas was evaluated in two regions of Mexico. MODIS data used in this study were the vegetative cover conversion product (MOD44A) and the vegetation indices (MOD13). The change detection methods were multidate classification, post-classification comparison and image enhancement techniques such as change vector, image differencing and selective ACP. The two versions of MOD44A products which were evaluated indicated no change in both study areas, they were not able to detect the deforested areas although some of parches reached meaningful superficies (> 100 ha). The image enhancement methods allow the elaboration of maps of change which presented a satisfactory accuracy

Éclairer le choix des outils de simulation des changements des modes d'occupation et d'usages des sols. Une approche comparative.

International audienceDurant les dernières décennies, une variété de modèles ont été développés pour simuler les changements futurs des modes d'occupation et d'usage des sols. Dans cette étude, nous avons comparé quatre logiciels de modélisation : CLUE-S, DINAMICA EGO, CA_Markov et Land Change Modeler. Nous avons examiné les différentes méthodes et outils disponibles dans chaque modèle pour reproduire les étapes nécessaires pour une telle approche de modélisation : 1) estimation de la quantité de changement, 2) caractérisation des changements observés par des variables explicatives, 3) allocation spatiale des changements, 4) reproduction des patrons spatiaux, 5) évaluation de la performance du modèle et 6) capacité pour développer des modèles sophistiqués. Pour illustrer cette analyse, les modèles ont été appliqués à des études de cas théoriques très simples. Nous avons comparé les différents résultats issus de cette démarche de modélisation (projection des surfaces de changements futurs, cartes de probabilité de changement, cartes des modes d'occupation et d'usage des sols futurs) afin d'objectiver nos conclusions portant sur la flexibilité et la capacité des modèles pour effectuer les différentes tâches listées. Le but de cette étude vise à éclairer les futurs utilisateurs à faire un choix de modèle approprié suivant leur problématique

Land change modeling: moving beyond projections

International audienceDuring the last decades, there has been an increasing interest from the academic and policy communities to monitor and model changes of the earth surface. Modeling environmental dynamics helps to understand changes that are taking place currently and to anticipate future evolutions. Prospective simulation supports decision-making for environmental management and land planning. This special issue is dedicated to advances in land change modeling. Land Use / Land Cover Change, also called LUCC, is certainly a prominent interface between natural and social dynamics because anthropogenic LUCC has a profound impact on Earth. LUCC impacts a large amount of highly relevant topics such as resource exploitation, climate change, biodiversity loss, etc. Land change modeling can provide transparent, efficient and sustainable decision support to these current and rising environmental problem

Inductive pattern-based land use/cover change models: A comparison of four software packages

International audienceLand use/cover change (LUCC), as an important factor in global change, is a topic that has recently received considerable attention in the prospective modeling domain. There are many approaches and software packages for modeling LUCC, many of them are empirical approaches based on past LUCC such as CLUES , DINAMICA EGO, CA_MARKOV and Land Change Modeler (both available in IDRISI). This study reviews the possibilities and the limits of these four modeling software packages. First, a revision of the methods and tools available for each model was performed, taking into account how the models carry out the different procedures involved in the modeling process: quantity of change estimate, change potential evaluation, spatial allocation of change, reproduction of temporal and spatial patterns, model evaluation and advanced modeling options. Additional considerations, such as flexibility and user friendliness were also taken into account. Then, the four models were applied to a virtual case study to illustrate the previous descriptions with a typical LUCC scenario that consists of four processes of change (conversion of forest to two different types of crops, crop abandonment and urban sprawl) that follow different spatial patterns and are conditioned by different drivers. The outputs were compared to assess the quantity of change estimates, the change potential and the simulated prospective maps. Finally, we discussed some basic criteria to define a " good " model

Antioxidant Potential is Correlated to ω6 / ω3 Ratio and Brasfield Score in Cystic Fibrosis Children

International audienceOBJECTIVES:Oxidative stress is associated with the condition of cystic fibrosis (CF), but no guidelines exist for its assessment or treatment. Our aim was to evaluate a test that measures the blood antioxidant capability in CF children.METHODS:This antioxidant capability was assessed by the Kit Radicaux Libres (KRL) test in 44 CF children (24 boys). We recorded also anthropometric measures, pulmonary function, CF severity scores, and plasma nutritional and inflammatory parameters (proteins, vitamins, erythrocyte fatty acids, and micronutrients). We performed univariate and multivariate analyses with linear regression models.RESULTS:The mean age at the first KRL assessment was 12.2 ± 3.8 years. Factors that correlated with decreased antioxidant capacity were mostly related to the severity of pulmonary disease [ forced expiratory volume at 1 second (FEV1), acute exacerbation, and congestion. In multivariate analysis, the correlation between Brasfield score and erythrocyte antioxidant potential remained significant (β = - 0.611, p < 0.001). Among nutritional factors, the ω6/ω3 ratio was significantly correlated to erythrocyte antioxidant potential (β = - 1.213, p = 0.01).CONCLUSION:The blood antioxidant capability, measured by the KRL test, appears to be an interesting biomarker to evaluate oxidative stress in CF. This study suggests that the ω6/ω3 ratio should be regarded as a nutritional marker in antioxidant management in CF children

Modelling Tropical Deforestation: A Comparison of Approaches

International audienceTropical deforestation, as an important factor in global change, is a topic that recently has received considerable attention. GIS-based spatially explicit models that intend to predict the location of land use/cover change (LUCC) can help scientists and policy makers to understand, anticipate and possibly prevent the adverse effects of land-use change. There are many approaches and softwares to model LUCC such as CLUE-S, DINAMICA GEOMOD and IDRISI. This study intends to compare these four modelling approaches. First, a review of methods and tools employed by each software to carry out the simulation was done. Then, the four packages were applied to a "virtual" case which involves a map of deforestation, which comprises two types of deforestation (forest to shifting agriculture and forest to pasture lands), along with several explanatory variables (drivers). Deforestation was modelled using the four approaches and the output maps were compared

Una comparación de programas de modelación de cambios de cobertura/ uso del suelo

En las últimas décadas, una gran cantidad de modelos de cambios de cobertura / uso del suelo (CCUS) enfocados a la simulación de procesos de cambio han sido desarrollados. Los CCUS pueden modelarse empíricamente mediante un análisis de los cambios pasados para desarrollar un modelo matemático que estima la probabilidad de cambio en función de un conjunto de variables explicativas. En general, el análisis espacial de los cambios se lleva a cabo a través de la comparación de dos mapas de cobertura/uso del suelo (CUS) de dos fechas anteriores. Esta comparación permite estimar los patrones y procesos de cambio (tipos de transiciones y tasas de cambio). El análisis de los cambios pasados en relación con lasLand use/cover changes (LUCC) are significant to a range of issues central to the study of global environmental change and have thus have received growing attention by decision makers and scientists. Over the last decades, a range of models of LUCC have been developed to meet land management needs, and to better understand, assess and project the future role of LUCC in the functioning of the earth system. This study intends to compare the possibilities and the limits of four modelling approaches: CLUE, DINAMICA EGO, CA_MARKOV and Land Change Modeler (both available in IDRISI). First, a review of methods and tools available for each model was done taking into account how the model carry out the different procedures involved in the modelling process (Estimation of the quantity of changes, finding of the relationship between the explanatory variables and the changes in order to assess the degree of change potential, change allocation, simulation of spatial patterns of changes, model evaluation). The four models were applied to simple case studies and model outputs were compared. variables explicativas permite mapear la probabilidad de las diferentes transiciones. Otros procedimientos, aplicados con el fin de crear un mapa prospectivo de CUS, involucran técnicas para asignar los cambios en el espacio y, finalmente, para reproducir los patrones espaciales de los paisajes. Por último, se lleva usualmente a cabo una evaluación del desempeño del modelo.Este estudio se llevó a cabo en el ámbito del proyecto Simulaciones geomáticas para modelizar dinámicas ambientales. Avances metodológicos y temáticos (BIA2008-00681)

Oxidative Phosphorylation Fueled by Fatty Acid Oxidation Sensitizes Leukemic Stem Cells to Cold

Dependency on mitochondrial oxidative phosphorylation (OxPhos) is a potential weakness for leukemic stem cells (LSC) that can be exploited for therapeutic purposes. Fatty acid oxidation (FAO) is a crucial OxPhos-fueling catabolic pathway for some acute myeloid leukemia (AML) cells, particularly chemotherapy-resistant AML cells. Here, we identified cold sensitivity at 4◦C (cold killing challenge; CKC4), commonly used for sample storage, as a novel vulnerability that selectively kills AML LSCs with active FAO-supported OxPhos while sparing normal hematopoietic stem cells. Cell death of OxPhos-positive leukemic cells was induced by membrane permeabilization at 4◦C; by sharp contrast, leukemic cells relying on glycolysis were resistant. Forcing glycolytic cells to activate OxPhos metabolism sensitized them to CKC4. Lipidomic and proteomic analyses showed that OxPhos shapes the composition of the plasma membrane and introduces variation of 22 lipid subfamilies between cold-sensitive and cold-resistant cells. Together, these findings indicate that steady-state energy metabolism at body temperature predetermines the sensitivity of AML LSCs to cold temperature, suggesting that cold sensitivity could be a potential OxPhos biomarker. These results could have important implications for designing experiments for AML research to avoid cell storage at 4◦C.</p