: Land cover changes and their climatic impacts in Mato Grosso, Brazil

http://confins.revues.org/6845International audienceChanges in land cover (deforestation, urbanization) in the Brazilian Amazon have a strong effect on the temperatures at local scale. This paper compares the temperatures of July 2007 between the urban area, the area deforested for pasture and forest in the region of Alta Floresta (Mato Grosso). The climatic changes are marked during the day but especially in the beginning and the end of the day (with significant differences between temperatures of 2 ° C to 4.3 ° C between the forest sector and the city center). The cleared area is generally warmer than the forest area. A second part of the paper concerns the study of the urban heat island for three cities of Mato Grosso: Rondonopolis, Sorriso and Sinop. Observations made by the mobile transect method in July 2009 show that temperatures are higher in dense urbanized areas than in residential areas. The effect of urban heat island is particularly well marked, especially at night and during the dry season but, locally, the role of topography and urban parks is also very sensitive (cool areas).Les changements d'occupation du sol (déforestation, urbanisation) en Amazonie brésilienne ont des conséquences sensibles sur les températures à l'échelle locale. Cet article présente une comparaison sur les températures du mois de juillet 2007 entre la zone urbanisée, la zone défrichée au profit de pâturages et celle couverte par la forêt dans la région d'Alta Floresta (Mato Grosso). Ces variations sont marquées en journée mais surtout en début et fin de journée (avec les écarts importants entre les températures de 2°C à 4,3°C entre le secteur forestier et le centre-ville). Le secteur défriché apparaît toujours globalement plus chaud que la région forestière. Une seconde partie de l'article concerne l'étude de l'îlot de chaleur urbain pour 3 villes du Mato Grosso : Rondonopolis, Sorriso et Sinop. Les observations réalisées par la méthode des transects mobiles en juillet 2009 montrent que les températures sont plus élevées dans les secteurs urbanisés denses, même si des différences existent au sein même des villes. L'effet d'îlot de chaleur urbain est particulièrement bien marqué surtout pendant la nuit et la saison sèche mais, localement, le rôle de la topographie et des parcs est bien sensible également (îlots de fraîcheur)

Avaliação das mudanças de uso do solo na bacia hidrográfica do rio Manso –MT– Brasil

The aim of this study is to show the land-cover changes after the construction of a hydroelectric dam in the central south state of Mato Grosso (Brazil) and the impact of this from an environmental point of view. With the use of satellite imagery it is possible to show which areas of vegetation flood and those which are always clear of the water: for example: cerrado, pasture land, forest, culture. The multi temporal study permits us to evaluate and quantify the change in land cover in the flood plain after the creation of the dam. This study presents the evolution of the land use in the flood plain during the 17 years, before and after the construction of the dam (between 1992 and 2009).To allow comparisons and interpretations of data, the images used were provided by the sensor Landsat-TM with atmospheric and geometric corrections. The useful agricultural land on the floodplain increased more than 100%, in 17 years. The areas of cerrado or forest which became arable or pasture formed 22.5 % of the total territory. The implantation of the dam and the land-use changes which resulted have had and will continue to have major repercussions on the environmental and territorial organisation.Pages: 6081-608

Évaluation du coût-efficacité des stratégies de dépistage de l'hépatite C en France

International audienceBACKGROUND & AIMS:In Europe, hepatitis C virus (HCV) screening still targets people at high risk of infection. We aim to determine the cost-effectiveness of expanded HCV screening in France.METHODS:A Markov model simulated chronic hepatitis C (CHC) prevalence, incidence of events, quality-adjusted life years (QALYs), costs and incremental cost-effectiveness ratio (ICER) in the French general population, aged 18 to 80 years, undiagnosed for CHC for different strategies: S1 = current strategy targeting the at risk population; S2 = S1 and all men between 18 and 59 years; S3 = S1 and all individuals between 40 and 59 years; S4 = S1 and all individuals between 40 and 80 years; S5 = all individuals between 18 and 80 years (universal screening). Once CHC was diagnosed, treatment was initiated either to patients with fibrosis stage ≥F2 or regardless of fibrosis. Data were extracted from published literature, a national prevalence survey, and a previously published mathematical model. ICER were interpreted based on one or three times French GDP per capita (€32,800).RESULTS:Universal screening led to the lowest prevalence of CHC and incidence of events, regardless of treatment initiation. When considering treatment initiation to patients with fibrosis ≥F2, targeting all people aged 40-80 was the only cost-effective strategy at both thresholds (€26,100/QALY). When we considered treatment for all, although universal screening of all individuals aged 18-80 is associated with the highest costs, it is more effective than targeting all people aged 40-80, and cost-effective at both thresholds (€31,100/QALY).CONCLUSIONS:In France, universal screening is the most effective screening strategy for HCV. Universal screening is cost-effective when treatment is initiated regardless of fibrosis stage. From an individual and especially from a societal perspective of HCV eradication, this strategy should be implemented.LAY SUMMARY:In the context of highly effective and well tolerated therapies for hepatitis C virus that are now recommended for all patients, a reassessment of hepatitis C screening strategies is needed. An effectiveness and cost-effectiveness study of different strategies targeting either the at-risk population, specific ages or all individuals was performed. In France, universal screening is the most effective strategy and is cost-effective when treatment is initiated regardless of fibrosis stage. From an individual and especially from a societal perspective of hepatitis C virus eradication, this strategy should be implemented