169 research outputs found
Détection et dénombrement de la moyenne et grande faune par imagerie visible et infrarouge thermique acquise à l'aide d'un aéronef sans pilote (ASP)
Lâinventaire aĂ©rien est une approche pratique pour effectuer lâinventaire de la grande faune sur de grands territoires; particuliĂšrement pour les zones peu accessibles. Toutefois, les limitations liĂ©es aux capacitĂ©s de dĂ©tection des observateurs, la coloration cryptique de certaines espĂšces fauniques et la complexitĂ© structurelle de certains habitats font en sorte que les inventaires ont gĂ©nĂ©ralement des biais qui sous-estiment la densitĂ© rĂ©elle de la population. Par ailleurs, peu dâĂ©tudes ont dĂ©montrĂ© la capacitĂ© dâeffectuer la dĂ©tection aĂ©rienne simultanĂ©e de plusieurs espĂšces. La dĂ©tection multiespĂšce peut sâavĂ©rer utile pour les espĂšces qui se cĂŽtoient spatialement afin de connaĂźtre leur utilisation de lâespace, pour Ă©tudier la relation proie/prĂ©dateur et pour limiter les coĂ»ts Ă un seul inventaire. Cette pratique sâavĂšre nĂ©anmoins trop exigeante pour les observateurs qui doivent dĂ©jĂ faire preuve de beaucoup de concentration pour dĂ©tecter une seule espĂšce lors dâun inventaire aĂ©rien traditionnel. Lâutilisation dâimagerie aĂ©rienne multispectrale acquise avec un aĂ©ronef sans pilote (ASP) reprĂ©sente une mĂ©thode potentielle pour la dĂ©tection dâune ou plusieurs espĂšces fauniques. Ce projet de recherche consistait donc dans un premier temps Ă dĂ©tecter, identifier et dĂ©nombrer Ă lâaide dâimagerie acquise avec un ASP et par traitements dâimages les cerfs de Virginie (Odocoileus virginianus). DiffĂ©rentes combinaisons de bandes spectrales, mĂ©thodes dâanalyses dâimages et rĂ©solutions spatiales ont Ă©tĂ© testĂ©es pour dĂ©terminer la mĂ©thode la plus efficace pour la dĂ©tection du cerf. Dans un deuxiĂšme temps, la meilleure mĂ©thode identifiĂ©e pour les cerfs a Ă©tĂ© utilisĂ©e et adaptĂ©e pour effectuer la dĂ©tection simultanĂ©e des bisons dâAmĂ©rique (Bison bison), des daims europĂ©ens (Dama dama), des loups gris (Canis lupus) et des wapitis (Cervus canadensis). Lâinventaire de la faune a Ă©tĂ© rĂ©alisĂ© au Centre dâobservation de la faune et dâinterprĂ©tation de lâagriculture de Falardeau Ă Saint-David-de-Falardeau, QuĂ©bec, Canada. Les rĂ©sultats dĂ©montrent que lâimagerie visible et infrarouge thermique avec une rĂ©solution spatiale de 0.8 cm/pixel combinĂ©e Ă une analyse dâimages par objet constitue la combinaison la plus efficace parmi celles testĂ©es pour la dĂ©tection des cerfs de Virginie. Tous les individus visibles Ă lâĆil nu sur les mosaĂŻques ont Ă©tĂ© dĂ©tectĂ©s. NĂ©anmoins, considĂ©rant lâobstruction visuelle causĂ©e par la canopĂ©e conifĂ©rienne, cette approche offre un taux de dĂ©tectabilitĂ© moyen de 0.5, comparable aux inventaires aĂ©riens classiques. La complexitĂ© structurelle de lâhabitat demeure ainsi un problĂšme non rĂ©solu. Quant Ă lâanalyse multiespĂšce, les bisons et les wapitis ont tous Ă©tĂ© dĂ©tectĂ©s mĂȘme en prĂ©sence dâautres espĂšces comme lâautruche (Struthio camelus), le coyote (Canis latrans) et lâours noir (Ursus americanus). Pour les daims et les loups, entre 0 Ă 1 individu par parcelle a Ă©tĂ© confondu avec les autres Ă©lĂ©ments du paysage tels que le sol. De plus, entre 0 Ă 2 individus par parcelle nâont pas Ă©tĂ© dĂ©tectĂ©s alors quâils Ă©taient prĂ©sents dans la ligne de vol. Non seulement cette approche a dĂ©montrĂ© sa capacitĂ© Ă dĂ©tecter une ou plusieurs espĂšces, mais Ă©galement son adaptabilitĂ© Ă cibler spĂ©cifiquement les espĂšces dâintĂ©rĂȘts pour le gestionnaire et Ă ignorer celles qui ne sont pas ciblĂ©es. Ce projet a donc permis de valider le potentiel des ASP pour lâacquisition dâimagerie dâune qualitĂ© permettant lâextraction de donnĂ©es dâinventaires. Cela ouvre la voie Ă lâutilisation de ce type de plateforme dâacquisition pour des applications reliĂ©es Ă la gestion de la faune grĂące Ă leur faible impact sonore et leur haut taux de revisite. Toutefois, la rĂ©glementation canadienne actuelle limite lâutilisation de ces appareils sur de faibles superficies. Il nâen demeure pas moins que la technologie peut ĂȘtre dĂ©veloppĂ©e en attendant les futurs progrĂšs du domaine des ASP et de la rĂ©glementation
Polysialylation of the Neural Cell Adhesion Molecule: Setting the Stage for Plasticity Across Scales of Biological Organization
Enseigner la rĂ©duction du recours aux pesticides: lâapport des didactiques aux questions dâaction, de reprĂ©sentation et dâapprentissage
International audienceRĂ©duire le recours aux pesticides dans les pratiques agricoles demande une meilleure prise en compte de la diversitĂ© des agroĂ©cosystĂšmes Ă gĂ©rer, ce qui engendre la complexification du raisonnement agronomique des agriculteurs. Une approche pluri-didactique des savoirs Ă enseigner en agronomie dans la transition agroĂ©cologique permet de considĂ©rer la multi-rĂ©fĂ©rentialitĂ©des savoirs dâaction (savoirs scientifiques, savoirs dâexpĂ©rience, dispositions et valeurs). Elle propose Ă©galement une organisation des apprentissages qui intĂšgre la complexitĂ© du raisonnement agronomique et la construction de lâĂ©thique professionnelle
Ruptures ou ajustements provoqués entre pratiques agricoles et enseignement de ces pratiques
La politique de rĂ©duction des intrants phytosanitaires (pesticides) touche les agriculteurs, mais aussi les enseignants des lycĂ©es agricoles. Ces derniers sont confrontĂ©s Ă des controverses, notamment au sein des classes, parmi les enfants dâagriculteurs. Nous nous centrons sur les apprentissages relatifs Ă la rĂ©duction dâintrants. Mobilisant une recherche pluridisciplinaire (agronomie, didactique, sociologie), nous interrogeons les structures, la division des tĂąches, la coordination des acteurs dans la redĂ©finition/appropriation de cette politique. Nous nous intĂ©ressons aux ruptures ou aux ajustements progressifs des pratiques et des normes vĂ©cus par les enseignants, les tuteurs et leurs Ă©lĂšves.Pest reduction management policy affects farmers, but also teachers of agricultural schools. They face controversial, particularly in classrooms, among the children of farmers. We focus here on learning related to the aim of the reduction of inputs, as learning object, and the debates as a learning process. Mobilizing multidisciplinary research (agronomy, teaching, sociology), this paper focus on three questions : the controversial debates as a learning opportunity ; the effects of the structures, the division of labor, the coordination of actors in redefining / appropriation by the actors of the vocational agricultural training system ; the interaction âon the plotâ beetween farmers/student as a conceptualisation moment. We are interested in ruptures or gradual adjustments of standards and practices experienced by teachers, tutors and students.Landwirte sind von der Politik zur Reduzierung pflanzenschĂŒtzender Produktionsmittel (Pestiziden) betroffen, aber auch Lehrer in Landwirtschaftsschulen. Sie sind mit Kontroversen konfrontiert, insbesondere in Klassen mit SchĂŒlern, der Eltern Landwirte sind. Wir konzentrieren uns auf die Ausbildung zum Thema Reduzierung von Produktionsmitteln. Dabei stĂŒtzen wir uns auf eine fachĂŒbergreifende Untersuchung (Agronomie, Didaktik, Soziologie) und hinterfragen die Strukturen, Aufgabenaufteilungen und die Koordinierung der Akteure bei der Neudefinition/Aneignung dieser Politik. Wir interessieren uns fĂŒr die völlige Umstellung oder allmĂ€hlichen Anpassungen der Methoden und der fĂŒr Lehrer, Tutoren und deren SchĂŒler vorgegebenen Normen.La polĂtica de reducciĂłn de los inputs fitosanitarios (pesticidas) afecta a los agricultores, pero tambiĂ©n a los docentes de las escuelas agrotĂ©cnicas. Se enfrentan con controversias, especialmente dentro de las clases, entre los hijos de agricultores. Nos centramos en los aprendizajes relativos a la reducciĂłn de inputs. Utilizando una investigaciĂłn pluridisciplinaria (agronomĂa didĂĄctica, sociologĂa) interrogamos las estructuras, la divisiĂłn de tareas, la coordinaciĂłn de los actores en la redefiniciĂłn/apropiaciĂłn de esta polĂtica. Nos interesamos por las rupturas o los ajustes progresivos de las prĂĄcticas y de las normas percibidos por los docentes, los tutores y sus alumnos
Hyperglycaemia and apoptosis of microglial cells in human septic shock
International audienceIntroductionThe effect of hyperglycaemia on the brain cells of septic shock patients is unknown. The objective of this study was to evaluate the relationship between hyperglycaemia and apoptosis in the brains of septic shock patients.MethodsIn a prospective study of 17 patients who died from septic shock, hippocampal tissue was assessed for neuronal ischaemia, neuronal and microglial apoptosis, neuronal Glucose Transporter (GLUT) 4, endothelial inducible Nitric Oxide Synthase (iNOS), microglial GLUT5 expression, microglial and astrocyte activation. Blood glucose (BG) was recorded five times a day from ICU admission to death. Hyperglycaemia was defined as a BG 200 mg/dL g/l and the area under the BG curve (AUBGC) > 2 g/l was assessed.ResultsMedian BG over ICU stay was 2.2 g/l. Neuronal apoptosis was correlated with endothelial iNOS expression (rho = 0.68, P = 0.04), while microglial apoptosis was associated with AUBGC > 2 g/l (rho = 0.70; P = 0.002). Neuronal and microglial apoptosis correlated with each other (rho = 0.69, P = 0.006), but neither correlated with the duration of septic shock, nor with GLUT4 and 5 expression. Neuronal apoptosis and ischaemia tended to correlate with duration of hypotension.ConclusionsIn patients with septic shock, neuronal apoptosis is rather associated with iNOS expression and microglial apoptosis with hyperglycaemia, possibly because GLUT5 is not downregulated. These data provide a mechanistic basis for understanding the neuroprotective effects of glycemic control
A Mouse Model for Chikungunya: Young Age and Inefficient Type-I Interferon Signaling Are Risk Factors for Severe Disease
Chikungunya virus (CHIKV) is a re-emerging arbovirus responsible for a massive outbreak currently afflicting the Indian Ocean region and India. Infection from CHIKV typically induces a mild disease in humans, characterized by fever, myalgia, arthralgia, and rash. Cases of severe CHIKV infection involving the central nervous system (CNS) have recently been described in neonates as well as in adults with underlying conditions. The pathophysiology of CHIKV infection and the basis for disease severity are unknown. To address these critical issues, we have developed an animal model of CHIKV infection. We show here that whereas wild type (WT) adult mice are resistant to CHIKV infection, WT mouse neonates are susceptible and neonatal disease severity is age-dependent. Adult mice with a partially (IFN-α/ÎČR+/â) or totally (IFN-α/ÎČRâ/â) abrogated type-I IFN pathway develop a mild or severe infection, respectively. In mice with a mild infection, after a burst of viral replication in the liver, CHIKV primarily targets muscle, joint, and skin fibroblasts, a cell and tissue tropism similar to that observed in biopsy samples of CHIKV-infected humans. In case of severe infections, CHIKV also disseminates to other tissues including the CNS, where it specifically targets the choroid plexuses and the leptomeninges. Together, these data indicate that CHIKV-associated symptoms match viral tissue and cell tropisms, and demonstrate that the fibroblast is a predominant target cell of CHIKV. These data also identify the neonatal phase and inefficient type-I IFN signaling as risk factors for severe CHIKV-associated disease. The development of a permissive small animal model will expedite the testing of future vaccines and therapeutic candidates
Changes in CRH and ACTH Synthesis during Experimental and Human Septic Shock
Context
The mechanisms of septic shock-associated adrenal insufficiency remain unclear. This study aimed at investigating the synthesis of corticotropin-releasing hormone (CRH) and vasopressin (AVP) by parvocellular neurons and the antehypophyseal expression of ACTH in human septic shock and in an experimental model of sepsis.
Objective
To test the hypothesis that ACTH secretion is decreased secondarily to alteration of CRH or AVP synthesis, we undertook a neuropathological study of the antehypophyseal system in patients who had died from septic shock and rats with experimental faecal peritonitis.
Methods
Brains obtained in 9 septic shock patients were compared to 10 nonseptic patients (controls). Parvocellular expression of AVP and CRH mRNA were evaluated by in situ hybridization. Antehypophyseal expression of ACTH, vasopressin V1b and CRH R1 receptors and parvocellular expression of iNOS in the PVN were evaluated by immunohistochemistry. The same experiments were carried out in a fecal peritonitis-induced model of sepsis. Data from septic rats with (n = 6) or without (n = 10) early death were compared to sham-operated (n = 8) animals.
Results
In patients and rats, septic shock was associated with a decreased expression of ACTH, unchanged expression of V1B receptor, CRHR1 and AVP mRNA, and increased expression of parvocellular iNOS compared to controls. Septic shock was also characterized by an increased expression of CRH mRNA in rats but not in patients, who notably had a greater duration of septic shock.
Conclusion
The present study suggests that in humans and in rats, septic shock is associated with decreased ACTH synthesis that is not compensated by its two natural secretagogues, AVP and CRH. One underlying mechanism might be increased expression of iNOS in hypothalamic parvocellular neurons
How valuable are your customers in the brand value co-creation process? The development of a Customer Co-Creation Value (CCCV) scale.
Despite an increasing amount of research on co-creation of value, in general, research on brand value co-creation remains limited. Particularly, how much value customers contribute to the brand value co-creation process remains unclear. This research develops in a series of eight studies the Customer Co-Creation Value (CCCV) measurement scale that helps firms assess the value of customers in the brand value co-creation process. The findings reveal that CCCV is a multidimensional construct consisting of two higher-order factors and seven dimensions: customer-owned resources (including brand knowledge, brand skills, brand creativity, and brand connectedness) and customer motivation (comprising brand passion, brand trust, and brand commitment). Further, the CCCV scale reliably and validly gauges the value customers contribute to a firm's brand. The CCCV framework helps marketing managers understand how customers can contribute to a firm's brand value cocreation efforts and how much value customers contribute to a brand in the co-creation process
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