90 resultados para Humidité du sol


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A series of nanostructured Ni-Zn ferrites Ni1-xZnxFe2O4 (x=0, 0.5 and 1) with a grain size from 24 to 65 nm have been prepared with a sol-gel method. The effect of composition and sintering temperature on morphology, magnetic properties, Curie temperature, specific heating rate at 295 kHz and hysteresis loss have been studied. The highest coercivity of 50 and 40 Oe, were obtained for NiFe2O4 and Ni0.5Zn0.5Fe2O4 samples with the grain size of 35 and 29 nm, respectively. The coercivity of Ni and Ni-Zn mixed ferrites decreased with temperature. The Bloch exponent was 1.5 for all samples. As the grain size increased, the Curie temperature of NiFe2O4 increased from 849 to 859 K. The highest saturation magnetization of 70 emu/g at 298 K and the highest specific heating rate of 1.6 K/s under radiofrequency heating at 295 kHz were observed over NiFe2O4 calcined at 1073 K. Both the magnitude of the hysteresis loss and the temperature dependence of the loss are influenced by the sintering temperature and composition.

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This study of the Mahavavy-Kinkony Wetland Complex (MKWC) assesses the impacts of habitat change on the resident globally threatened fauna. Located in Boeny Region, northwest Madagascar, the Complex encompasses a range of habitats including freshwater lakes, rivers, marshes, mangrove forests, and deciduous forest. Spatial modelling and analysis tools were used to (i) identify the important habitats for selected, threatened fauna, (ii) assess their change from 1950 to 2005, (iii) detect the causes of change, (iv) simulate changes to 2050 and (v) evaluate the impacts of change. The approach for prioritising potential habitats for threatened species used ecological science techniques assisted by the decision support software Marxan. Nineteen species were analysed: nine birds, three primates, three fish, three bats and one reptile. Based on knowledge of local land use, supervised classification of Landsat images from 2005 was used to classify the land use of the Complex. Simulations of land use change to 2050 were carried out based on the Land Change Modeler module in Idrisi Andes with the neural network algorithm. Changes in land use at site level have occurred over time but they are not significant. However, reductions in the extent of reed marshes at Lake Kinkony and forests at Tsiombikibo and Marofandroboka directly threaten the species that depend on these habitats. Long term change monitoring is recommended for the Mahavavy Delta, in order to evaluate the predictions through time. The future change of Andohaomby forest is of great concern and conservation actions are recommended as a high priority. Abnormal physicochemical properties were detected in lake Kinkony due to erosion of the four watersheds to the south, therefore an anti-erosion management plan is required for these watersheds. Among the species of global conservation concern, Sakalava rail (Amaurornis olivieri), Crowned sifaka (Propithecus coronatus) and dambabe (Paretroplus dambabe) are estimated the most affected, but at the site level Decken’s sifaka (Propithecus deckeni), kotsovato (Paretroplus kieneri) and Madagascan big-headed turtle (Erymnochelys madagascariensis) are also threatened. Local enforcement of national legislation on hunting means that MKWC is among the sites where the flying fox (Pteropus rufus) and Madagascan rousette (Rousettus madagascariensis) are well protected. Ecological restoration, ecological research and actions to reduce anthropogenic pressures are recommended.

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This article examines how in post-war France slang became a byword for the noir genre. It considers the mechanisms, models, networks and translators' practices which set the tone for the "Série Noire”, whose influence, both written and on the screen, had, within a decade, become, a "mythology" studied by Roland Barthes. It argues that this use of slang is redolent of the inauthenticity which characterises this stage in the reception of the Noir genre in France. It is certain that this artificial French slang is far from devoid of charm, or even mystery. But it tends to depreciate and deform the translated works and seems to be the hallmark of an era that might have defined and acclimatised Noir fiction in France, yet remains one which has not fully understood the gravity of its purpose. While such translations seem outdated nowadays (if not quite incomprehensible ), original works written at the time in French by writers inspired by the model of " pseudo- slang" and the fashionability of American popular culture have benefited from them. In this very inauthenticity, derivative novels have found a licence for invention and freedom, with authors such as Cocteau hailing it as a revival of the French written language. We see here how the adventures of Commissaire San Antonio, by Frédéric Dard constitute the best examples of this new creativity in French and draw upon a template set for the reception of American literature

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A description, and analysis, of an empirical investigation of the effectiveness of affirmative action in the Northern Ireland employment

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A novel method for the preparation of titania sol–gel derived oxygen sensors based on the ruthenium(II) dye, [Ru(bpy)3]2+, is described. A titania sol–gel paste film was cast onto microscope slides, and the dye ion-paired to the deprotonated, hydroxylated groups on the film's surface from an aqueous solution of the dye at pH 11. The resulting sensor film is extremely oxygen sensitive, with a PO2 (S = 1/2) value (i.e. the partial pressure of oxygen required in order to reduce the original, oxygen free, luminescence intensity by 50%) of 0.011 atm. The sensor undergoes 95% response to oxygen in 4 s, and shows 95% recovery of its luminescence in argon within 7 s.