Welche Bodenzusätze helfen bei der Lösung von Problemen mit Feldaufgang in Spinat?

Damping-off of spinach, caused by soil-borne pathogens, is one of the most serious problems in organic spinach production. To overcome these problems soil amendments based on specific strains of micro-organisms or based on organic material are proposed. In pot experiments under controlled conditions 14 microbial strains and six organic soil amendments were tested on their ability to suppress soil borne diseases and to improve plant stand establishment. In a subsequent field experiment with the best treatments, soil amendments with compost showed the best effect while products based on single strains of micro-organisms failed to improve plant stand establishment. It is concluded that under high disease pressure a diverse population of microorganisms as it can be found in compost may more effectively suppress soil borne diseases than single strains of micro-organisms

Développement de l'expertise chez les superviseurs de stage en formation à l'enseignement

Ce travail présente une étude ayant pour but de décrire le développement de l'expertise chez les superviseurs de stage en éducation préscolaire et en enseignement primaire. Trois objectifs sont poursuivis. Il s'agit (1) d'analyser l'importance accordée aux différents rôles du superviseur par des superviseurs experts en éducation préscolaire et en enseignement primaire, (2) de décrire les perceptions que ces superviseurs ont à leur propre égard concernant leurs connaissances, compétences et habiletés, et enfin (3) de décrire le développement de leur expertise. Les données de cette recherche ont été recueillies à l'aide d'un questionnaire et d'un entretien en profondeur utilisés auprès de superviseurs experts. Le questionnaire a été rempli par 40 superviseurs d'universités québécoises francophones. Cinq entretiens ont été réalisés auprès de volontaires.\ud Les résultats relatifs à l'importance des rôles du superviseur universitaire de stage indiquent que les experts considèrent le rôle de mentor comme étant le plus important, comparativement aux rôles d'interprète et de personne ressource. Ces résultats sont en partie similaires à ceux de Enz, Freeman et Wallin (1996). Par rapport à ces mêmes rôles, les résultats montrent, de plus, que les superviseurs estiment avoir augmenté leur niveau de compétences et de connaissances au cours de leur carrière comme superviseur. Ils estiment que leurs forces se situent dans les aspects pratiques, ainsi que dans les aspects plus personnels tels que des qualités liées à leur personnalité. Enfin, la recherche montre que l'expertise des superviseurs se développe grâce à leur intérêt pour ce rôle, à leur capacité d'analyse personnelle et réflexive, aux nombreuses situations problématiques qu'ils ont à résoudre, aux échanges qu'ils ont avec des personnes de leur entourage en milieu de travail et aux diverses formations et perfectionnements qu'ils suivent, tout cela sans oublier leur vie personnelle qui amène son lot d'expériences humaines. ______________________________________________________________________________ MOTS-CLÉS DE L’AUTEUR : Expertise, Superviseur de stage, Enseignement, Rôles

Determinants of anemia and hemoglobin concentration in haitian school-aged children

Anemia diminishes oxygen transport in the body, resulting in potentially irreversible growth and developmental consequences for children. Limited evidence for determinants of anemia exists for school-aged children. We conducted a cluster randomized controlled trial in Haiti from 2012 to 2013 to test the efficacy of a fortified school snack. Children (N = 1,047) aged 3–13 years were followed longitudinally at three time points for hemoglobin (Hb) concentrations, anthropometry, and bioelectrical impedance measures. Dietary intakes, infectious disease morbidities, and socioeconomic and demographic factors were collected at baseline and endline. Longitudinal regression modeling with generalized least squares and logit models with random effects identified anemia risk factors beyond the intervention effect. At baseline, 70.6% of children were anemic and 2.6% were severely anemic. Stunting increased the odds of developing anemia (adjusted odds ratio [OR]: 1.48, 95% confidence interval [CI]: 1.05–2.08) and severe anemia (adjusted OR: 2.47, 95% CI: 1.30–4.71). Parent-reported vitamin A supplementation and deworming were positively associated with Hb concentrations, whereas fever and poultry ownership showed a negative relationship with Hb concentration and increased odds of severe anemia, respectively. Further research should explore the full spectrum of anemia etiologies in school children, including genetic causes

Olive baboons, Papio anubis, adjust their visual and auditory intentional gestures to the visual attention of others

International audienceAlthough nonhuman primates' gestural communication is often considered to be a likely precursor of human language, the intentional properties in this communicative system have not yet been entirely elucidated. In particular, little is known about the intentional nature of monkeys' gestural signalling and related social understanding. We investigated whether olive baboons can (1) adjust their requesting gestures to the visual attention of the experimenter with special emphasis on the state of the eyes (open versus closed), and (2) flexibly tailor visual and auditory-based gestures to elaborate their communication as a function of whether or not the experimenter can see them. Using a food-requesting paradigm, we found monkeys able to favour either visual or auditory-based requesting gestures to match the experimenter's visual attention. Crucially, when the human was not visually attending, they silenced visual gestures to some extent but performed more attention-getting gestures. This is, to our knowledge, the first report of monkeys elaborating attention-getting signals to compensate for communication breakdown. Gestural communication was also supported by gaze alternation between the experimenter's face and the food, especially when the human was visually attending. These findings offer evidence that olive baboons understand the state of the eyes in others' visual attention and use requesting gestures intentionally. They emphasize that Old World monkeys shift to acoustic communication when the recipient is not visually attending. In contrast to that of human infants and great apes, this acoustic communication is purely gestural, not vocal

The role of urban structures in the distribution of wasteland flora in the Greater Paris Area, France

International audienceWastelands are likely to host a significant part of urban floristic diversity but have received limited attention because they are not considered interesting green zones. Here, we explore the potential role of wastelands in maintaining urban biodiversity to help define effective urban management plans. We quantified floristic diversity in 98 wasteland sites of Hauts-de-Seine, one of the most densely populated areas in France, and characterized the environmental parameters and spatial distribution of sites to identify some of the factors that influence plant species composition and to explore the impact of urban environment on the floristic interest of wastelands. Their floristic richness represented 58% of the total richness observed in the whole study area. Site richness depended on site area (the largest sites were the richest) and site age, with a maximum in sites of intermediate age (4-13 years). In the largest sites only (>2,500 m 2), the floristic distance among sites was positively correlated with geographic distance, which suggests that migration of species among large sites partly controls local floristic composition. In contrast, the environmental distance among sites was not correlated with floristic distance. Finally, we showed that the presence of collective and individual dwellings within 200 m of a wasteland decreased its floristic rarity, whereas the presence of rivers or ponds increased it. We derive several recommendations to optimize the management of wastelands with respect to conservation of urban biodiversity

Use of extensive habitat inventories in biodiversity studies

International audienceLarge monitoring programs exist in many countries and are necessary to assess present and past biodiversity status and to evaluate the consequences of habitat degradation or destruction. Using such an extensive data set of the floristic richness in the Paris Ile-de-France region (France), we compared different sampling efforts and protocols in different habitat units to highlight the best methods for assessing the actual plant biodiversity. Our results indicate that existing data can be used for a general understanding of site differences, but analysts should be aware of the limitations of the data due to non-random selection of sites, inconsistent observer knowledge, and inconsistent sampling period. The average species diversity recorded in a specific habitat does not necessarily reflect its actual diversity, unless the monitoring effort was very strong. Overall, increasing the sampling effort in a given region allows improvement of the (1) number of habitats visited, (2) the total sampled area for a given habitat type, (3) the number of seasons investigated. Our results indicate that the sampling effort should be planned with respect to these functional, spatial and temporal heterogeneities, and to the question examined. While the effort should be applied to as many habitats as possible for the purpose of capturing a large proportion of regional diversity, or comparing different regions, inventories should be conducted in different seasons for the purpose of comparing species richness in different habitats

Développement d'un procédé propre assisté par CO2 supercritique pour la production de particules de polyamide (caractérisation et faisabilité)

Cette thèse vise à la production de poudre de polymère par un procédé continu, en une seule étape et supprimant l'utilisation des solvants organiques en faveur de celle du CO2 supercritique. Avant de développer le procédé, une caractérisation du mélange CO2/polymère a été effectuée. Des mesures de solubilité, de gonflement et de coefficient de diffusion du CO2 ont été réalisées et représentées par différents modèles. De plus, une technique de rhéologie capillaire en ligne a été développée, permettant la mesure de viscosité du polymère, seul ou en mélange, avec le CO2 dans les conditions du procédé. Un montage batch a ensuite permis de tester l'influence des paramètres opératoires sur de faibles quantités. Parallèlement, le procédé continu a été étudié sur une extrudeuse équipée d'outils de mélange du CO2 dans le polymère fondu. L'efficacité et l'homogénéité du mélange ont été étudiées à travers la fabrication de mousses de polymères et la réalisation de distributions de temps de séjour par spectroscopie Raman en ligne. L'ajout d'un dispositif de pulvérisation spécifique a conduit à l'obtention de poudres d'aspect fibreux avec deux populations de tailles.Polymer powders are widely used in industry and are traditionally manufactured by processes using organic solvent or by grinding low molecular weight polymers with a post-polymerization step. This thesis aimss at the generation of polymer powders with a single-step continuous process, based on the use of supercritical CO2, hence without organic solvent. Before developing this process, the characterization of the mixture CO2/polymer was done. Solubility measurements were carried out and fitted with the Sanchez-Lacombe equation of state. Moreover, a capillary rheometry technique was implemented on-line, allowing the measurement of the viscosity of the polymer alone or in mixture with CO2, under process conditions. The modeling of swelling as a function of time led to the evaluation of the diffusion coefficient of CO2 into the polymer. Afterwards, two experimental devices were designed. A batch process with a pressurized autoclave was used to determine the influence of experimental parameters on powder production, with small amounts of material. Formation of small fibrous particles was obtained. In parallel, the continuous process was studied on an extruder adapted to CO2 introduction and equipped with mixing devices. This study, which led to foam manufacture, was used to evaluate efficiency and homogeneity of the mixing. Residence time distributions were determined by Raman spectroscopy on the die in order to evaluate the flowing in the extruder under different conditions. The equipment was also fitted with a specific nozzle allowing co-injection of hot air. Production of fibrous particles with two different size ranges was obtained.TOULOUSE-INP (315552154) / SudocSudocFranceF