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Search Results: 1 - 10 of 8324 matches for " Fran?ois Bretagnolle "
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Managing biotic interactions for ecological intensification of agroecosystem
Sabrina Gaba,Franois Bretagnolle,Thierry Rigaud,Laurent PHILIPPOT
Frontiers in Ecology and Evolution , 2014, DOI: 10.3389/fevo.2014.00029
Abstract: Agriculture faces the challenge of increasing food production while simultaneously reducing the use of inputs and delivering other ecosystem services. Ecological intensification of agriculture is a paradigm shift, which has recently been proposed to meet such challenges through the manipulation of biotic interactions. While this approach opens up new possibilities, there are many constraints related to the complexity of agroecosystems that make it difficult to implement. Future advances, which are essential to guide agricultural policy, require an eco-evolutionary framework to ensure that ecological intensification is beneficial in the long term.
Demographic history, genetic structure and gene flow in a steppe-associated raptor species
Jesus T Garcia, Fernando Alda, Julien Terraube, Franois Mougeot, Audrey Sternalski, Vincent Bretagnolle, Beatriz Arroyo
BMC Evolutionary Biology , 2011, DOI: 10.1186/1471-2148-11-333
Abstract: Consistent with our hypothesis, Montagu's harrier has relatively low genetic variation at the mitochondrial DNA. The highest levels of genetic diversity were found in coastal Spain, France and central Asia. These areas, which were open landscapes during the Holocene, may have acted as refugia when most of the European continent was covered by forests. We found significant genetic differentiation between two population groups, at the SW and NE parts of the species' range. Two events of past population growth were detected, and occurred ca. 7500-5500 and ca. 3500-1000 years BP in the SW and NE part of the range respectively. These events were likely associated with vegetation shifts caused by climate and human-induced changes during the Holocene.The relative genetic homogeneity observed across populations of this steppe raptor may be explained by a short isolation time, relatively recent population expansions and a relaxed philopatry. We highlight the importance of considering the consequence of isolation and colonization processes in order to better understand the evolutionary history of steppe species.Contemporary patterns of genetic diversity and population structure reflect not only current patterns of genetic exchange but also past dispersal processes and levels of gene flow among populations during historical climatic events [1,2]. In many species inhabiting temperate zones, climate-vegetation feedbacks during the Pleistocene caused range contractions to lower latitudes followed by range expansions during interglacial periods [2,3], which in turn promoted much of the diversification observed today. However, not all species responded similarly to these past climatic events. Species-specific responses to these changes are the result of a complex interplay between the behavioral, physiological and ecological characteristics of the species, including their biogeographic origin, habitat preferences and dispersal capabilities [4]. Climatic conditions prevailing at dif
Reconciling Pesticide Reduction with Economic and Environmental Sustainability in Arable Farming
Martin Lechenet, Vincent Bretagnolle, Christian Bockstaller, Franois Boissinot, Marie-Sophie Petit, Sandrine Petit, Nicolas M. Munier-Jolain
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0097922
Abstract: Reducing pesticide use is one of the high-priority targets in the quest for a sustainable agriculture. Until now, most studies dealing with pesticide use reduction have compared a limited number of experimental prototypes. Here we assessed the sustainability of 48 arable cropping systems from two major agricultural regions of France, including conventional, integrated and organic systems, with a wide range of pesticide use intensities and management (crop rotation, soil tillage, cultivars, fertilization, etc.). We assessed cropping system sustainability using a set of economic, environmental and social indicators. We failed to detect any positive correlation between pesticide use intensity and both productivity (when organic farms were excluded) and profitability. In addition, there was no relationship between pesticide use and workload. We found that crop rotation diversity was higher in cropping systems with low pesticide use, which would support the important role of crop rotation diversity in integrated and organic strategies. In comparison to conventional systems, integrated strategies showed a decrease in the use of both pesticides and nitrogen fertilizers, they consumed less energy and were frequently more energy efficient. Integrated systems therefore appeared as the best compromise in sustainability trade-offs. Our results could be used to re-design current cropping systems, by promoting diversified crop rotations and the combination of a wide range of available techniques contributing to pest management.
Multilevel comparison of large urban systems
Denise Pumain,Elfie Swerts,Clémentine Cottineau,Céline Vacchiani-Marcuzzo,Antonio Ignazzi,Anne Bretagnolle,Franois Delisle,Robin Cura,Liliane Lizzi,Solène Baffi
Physics , 2015, DOI: 10.4000/cybergeo.26730
Abstract: For the first time the systems of cities in seven countries or regions among the largest in the world (China, India, Brazil, Europe, the Former Soviet Union (FSU), the United States and South Africa) are made comparable through the building of spatio-temporal standardised statistical databases. We first explain the concept of a generic evolutionary urban unit ("city") and its necessary adaptations to the information provided by each national statistical system. Second, the hierarchical structure and the urban growth process are compared at macro-scale for the seven countries with reference to Zipf's and Gibrat's model: in agreement with an evolutionary theory of urban systems, large similarities shape the hierarchical structure and growth processes in BRICS countries as well as in Europe and United States, despite their positions at different stages in the urban transition that explain some structural peculiarities. Third, the individual trajectories of some 10,000 cities are mapped at micro-scale following a cluster analysis of their evolution over the last fifty years. A few common principles extracted from the evolutionary theory of urban systems can explain the diversity of these trajectories, including a specific pattern in their geographical repartition in the Chinese case. We conclude that the observations at macro-level when summarized as stylised facts can help in designing simulation models of urban systems whereas the urban trajectories identified at micro-level are consistent enough for constituting the basis of plausible future population projections.
When neurological symptoms hides a nephrologic pathology and a cardiac abnormality  [PDF]
Clotilde Muller, Bernadette Faller, Franois Sellal, Franois Chantrel
Open Journal of Internal Medicine (OJIM) , 2011, DOI: 10.4236/ojim.2011.11002
Abstract: We bring report the case of a young woman who presents with neurological symptoms, and to which the practised investigations led to the discovery in chain of unexpected pathologies. These neurological disorders were revealing of the picture associating a nephrotic syndrome and a patent foramen ovale. This foramen was the major route of a rain of emboles ring peripheral favored by the nephrotic syndrome towards the cerebral hemispheres.
Labeled HepasphereTM behavior during venous drainage simulation at 1.5T  [PDF]
Hassan Jassar, Franois Langevin
Journal of Biomedical Science and Engineering (JBiSE) , 2010, DOI: 10.4236/jbise.2010.311142
Abstract: Stability of the magnetic resonance (MR) contrast agent inside vascular occlusion agents is important for their localization with magnetic resonance imaging (MRI). The aim of this paper is to study the behaviour of the superparamagnetic iron oxide (SPIO) within Hepaspheres? microparticles (MP) by MRI when they are submitted to negative pressure induced by venous drainage of a tumor. Therefore, a venous drainage model was established and three parameters were taken into account according to physiologic parameters in tumors: pH, temperature and flow blood rate. Four cycles of pumping were performed with the presence of labeled Hepaspheres? with Endorem®. Several MR images of MP and perfusion liquid were taken before and after pumping. Endorem® release was determined after correction of non-uniformity intensities in MR images. Intensity variation according to spatial position, coil and MR acquisition parameters was studied. Labeled microparticles (LB*MP) appeared as black spots in MRI images whatever duration and pH. Our model demonstrates the stability of the SPIO inside the occlusion agent during time. Moreover, the proposed correction method proves the reduction of the intensity non-uniformity in MRI images.
Architectural Model of a Biological Retina Using Cellular Automata  [PDF]
Franois Devillard, Bernard Heit
Journal of Computer and Communications (JCC) , 2014, DOI: 10.4236/jcc.2014.214008
Abstract: Developments in neurophysiology focusing on foveal vision have characterized more and more precisely the spatiotemporal processing that is well adapted to the regularization of the visual information within the retina. The works described in this article focus on a simplified architectural model based on features and mechanisms of adaptation in the retina. Similarly to the biological retina, which transforms luminance information into a series of encoded representations of image characteristics transmitted to the brain, our structural model allows us to reveal more information in the scene. Our modeling of the different functional pathways permits the mapping of important complementary information types at abstract levels of image analysis, and thereby allows a better exploitation of visual clues. Our model is based on a distributed cellular automata network and simulates the retinal processing of stimuli that are stationary or in motion. Thanks to its capacity for dynamic adaptation, our model can adapt itself to different scenes (e.g., bright and dim, stationary and moving, etc.) and can parallelize those processing steps that can be supported by parallel calculators.
Ethical Decision-Making in Clinical Nutritional Practice  [PDF]
Franois P. R. de Villiers
Food and Nutrition Sciences (FNS) , 2011, DOI: 10.4236/fns.2011.26089
Abstract: Ethics requires a critical evaluation of assumptions and arguments about norms and values; what should be done and what should not. Practitioners should practice ethically, and the professions should be at the forefront of applied ethics. There are four principles, patient autonomy, beneficence, non-maleficence and justice, which are guides to ethical day-to-day practice. Patient autonomy: Autonomy means self-rule by persons of their thoughts and actions. Patient autonomy requires the practitioner to realise that patients have the right to be involved in decision-making on their own behalf. Beneficence refers to the duty of the practitioner to do the best for the patient. The benefits of breast-feeding are many, and the eventual outcome on health enormous. Nevertheless, health-care workers are diffident in promoting breast-feeding, and readily accept excuses for not breast-feeding, contrary to the principle of beneficence. Non-maleficence refers to the duty of the practitioner not to do harm; it requires the practitioner to withhold harmful therapies; Vitamin E, for example, has been proven to be ineffective as an antioxidant in humans, and large doses have been proven to increase mortality. Yet these are the doses available in supermarkets and “Health shops”. Nutritionists should actively advise against harmful “dietary supplementation”. Distributive justice requires every patient to have an equal opportunity to obtain appropriate therapy. There are relatively few nutritionists and dieticians in South Africa, and indeed in the entire African continent, but proportionately even fewer in the areas of greatest need. A case illustrates the application of these ethical principles to show how they can be applied to our daily practice. Using these four principles is a practical approach to solving ethical dilemmas.
Microwave-Assisted Polyesterification Process in Bulk and Aqueous Media  [PDF]
Nassima Mazouzi-Sennour, Franois Henry
International Journal of Organic Chemistry (IJOC) , 2014, DOI: 10.4236/ijoc.2014.41003
Abstract: Microwave irradiation in polymer chemistry is an emerging research field. This type of heating can enhance the rate of reaction and improve the specific characteristics of the formed polymer. In this context, the present paper focuses on selective microwave (MW) heating and its influence on the polyesterification reaction. As a reaction model, the polyesterification of sebacic acid with decanediol, in bulk and in aqueous emulsion is investigated. The reaction was catalyzed by using 4-dodecylbenzenesulfonic acid (DBSA), which plays a catalytic and surfactant role. Both in bulk and in aqueous media, a polyester with higher molecular weight is obtained in MW heating compared to the conventional heating.
Influence of Microwave Irradiation on Hydrolysis Reaction of Sunflower Oil in Aqueous Emulsion  [PDF]
Nassima Mazouzi-Sennour, Franois Henry
International Journal of Organic Chemistry (IJOC) , 2014, DOI: 10.4236/ijoc.2014.41004
Abstract: Microwave irradiation (MW) has been widely applied as heating in chemical processing. It offers a clean, convenient and inexpensive method of heating which often results in higher yields and shorter reaction times. Here, we study the microwave heating influence on the hydrolysis of the triglyceride (sunflower oil) in aqueous emulsion catalyzed by using 4-dodecylbenzenesulfonic acid (DBSA). The progress of the hydrolysis reaction was determined by Fourier Transform Infrared spectroscopy (FTIR). The effects of temperature, reaction time and the catalyst nature and concentration on the hydrolysis reaction were investigated. The hydrolysis was carried out at temperatures ranging between 90°C and 150°C. The polarity of the reaction medium accelerated this reaction.
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