Le rôle des objets-frontières dans l’apprentissage et la performance d’équipes d’étudiants travaillant à des projets de conception de bâtiments

La pédagogie universitaire et le monde du travail sont tous deux influencés par les technologies de l’information. Dans le domaine de la conception de bâtiments durables, ces technologies servent d’objets-frontières, c’est-à-dire d’interfaces qui facilitent les interactions et le partage des connaissances nécessaires au travail multidisciplinaire. Fondé sur les théories de l’apprentissage social et de l’action située ainsi que sur des données probantes issues de plusieurs domaines dont la gestion de projet, l’architecture, l’ingénierie civile, l’ingénierie des systèmes et la conception participative, cet article présente un réseau nomologique illustrant les relations entre des phénomènes individuels et collectifs en jeu au sein d’une équipe de projet et qui déterminent l’apprentissage groupal et la performance d’un projet. Il en résulte un corpus de connaissances utiles aux pédagogues ainsi que six hypothèses vérifiables que les chercheurs peuvent tester.University pedagogy and the world of work are both influenced by information technologies. In the field of design for sustainable construction, these technologies are used as boundary objects, which means as interfaces driving interactions and knowledge sharing required for multidisciplinary work. Based on social learning and situated action theories, and on convincing data coming from multiple domains such as project management, architecture, civil engineering, system engineering, and participatory design, this article presents a nomological network illustrating relationships between individual and collective phenomena in play within a project team, and which determine group learning and project performance. This results into a useful body of knowledge for teachers and six verifiable hypotheses that researchers can test

Cambios en las fracciones de fósforo del suelo causado por la agricultura sin reposición de nutrientes. Un caso de estudio

Estudios previos en suelos de la región pampeana indicaron que los fosfatos de calcio prevalecen dentro de la compleja mezcla de compuestos de fósforo (P) del suelo. En el presente trabajo, estudiamos las diferentes fracciones de P del suelo en una situación puntual de la región Pampeana. El muestreo fue llevado a cabo en un establecimiento localizado cerca de la ciudad de Junín (-34,585; -60,9589), en un suelo Hapludoll típico, serie Junín. El establecimiento se dedicó al pastoreo y cultivos esporádicos, pero desde hace 30 años cambió a agricultura continua. En ningún momento la fertilización igualó la pérdida de nutrientes causado por los cultivos. Las fracciones de P del suelo fueron determinadas utilizando una versión modificada del método clásico de extracción de Chang y Jackson. El P ligado al calcio disminuyó en términos absolutos y relativos (49,1%) y el fósforo ligado al aluminio y al hierro aumentaron (144,8 y 100,4%, respectivamente). Sin embargo, la proporción de estas últimas fracciones fue afectada por cambios en las fracciones de P orgánico y residual. Si el presente hallazgo puede ser generalizado, indicaría un cambio en la composición de las fracciones de P para los suelos más agriculturizados de la región.Previous studies in soils of the Pampas region indicate the prevalence of calcium phosphates within the very complex mix of phosphorus (P) compounds in the soils. We studied the changes in P fractions in a punctual situation in the Pampas region. The sampling was carried out in a farm located near the city of Junín (-34.585; -60.9589) and the soil was Junín series Typic Hapludoll. The farm was devoted to grazing and sporadic crops, but from the last 30 years changed to continuous agriculture. At no time fertilization matched nutrients removal by crops. The soil P fractions were determined using an improved version of the classical Chang and Jackson method. Phosphorus linked to calcium decreased in absolute and relative terms (49.1%) and P linked to aluminum and iron increased (144.8 and 100.4%, respectively). However, the proportion of latter fractions was affected by the changes in organic and residual P fractions. If present punctual finding could be generalized, it would indicate a change in the composition of P fractions in the most cropped soils of the regionFil: Barresi, O.. Universidad de Buenos Aires. Facultad de Agronomía; ArgentinaFil: Lavado, Raul Silvio. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones en Biociencias Agrícolas y Ambientales. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones en Biociencias Agrícolas y Ambientales; ArgentinaFil: Chiocchio, Viviana Monica. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones en Biociencias Agrícolas y Ambientales. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones en Biociencias Agrícolas y Ambientales; Argentin

Climate change promotes hybridisation between deeply divergent species

Rare hybridisations between deeply divergent animal species have been reported for decades in a wide range of taxa, but have often remained unexplained, mainly considered chance events and reported as anecdotal. Here, we combine field observations with long-term data concerning natural hybridisations, climate, land-use, and field-validated species distribution models for two deeply divergent and naturally sympatric toad species in Europe (Bufo bufo and Bufotes viridis species groups). We show that climate warming and seasonal extreme temperatures are conspiring to set the scene for these maladaptive hybridisations, by differentially affecting life-history traits of both species. Our results identify and provide evidence of an ultimate cause for such events, and reveal that the potential influence of climate change on interspecific hybridisations goes far beyond closely related species. Furthermore, climate projections suggest that the chances for these events will steadily increase in the near future

Influence of the insecticide dimethoate on arbuscular mycorrhizal colonization and growth in soybean plants

Application to the soil of the insecticide dimethoate had no effect on the growth of soybean colonized by the arbuscular mycorrhizal (AM) fungus Glomus mosseae and by the indigenous AM fungus. The application of the recommended concentration of dimethoate decreased the percentage of colonization of soybean by the indigenous AM population, but no significant effect was observed on the colonization of soybean inoculated with G. mosseae. The insecticide did not affect the germination of G. mosseae spores; however, 0.5 mg/l of dimethoate increased the germination of Gigaspora roseae and 5 mg/l of dimethoate decreased the germination of Scutellospora castaneae spores

Effect of the fungicide benomyl on spore germination and hyphal length of the arbuscular mycorrhizal fungus Glomus mosseae

The fungicide benomyl inhibited spore germination and hyphal length of the arbuscular mycorrhizal fungus Glomus mosseae when applied at doses of 21.25 μg/ml (agronomic dose), 10.62 μg/ml and 10 μg/ml. G. mosseae was able to germinate in the presence of 2.12 μg/ml of benomyl, and the percentage of spore germination was unaffected by dosis of 0.1, 0.01 and 0.001 μg/ml of the fungicide. However, all doses of fungicide tested in this study decreased the hyphal length. When ungerminated G. mosseae spores previously exposed to benomyl were transferred to water-agar medium without benomyl, the maximum germination was 16%. Small spores of G. mosseae were more resistant to benomyl than the larger ones. Our results show some of the factors which can explain the variability of the effect of benomyl on arbuscular mycorrhizal fungi

Continuous Sugar Beet Pulp Pretreatment and Bioconversion in a Biorefinery Context

Valorisation of agricultural wastes, such as Sugar Beet Pulp (SBP), for production of biofuels and value-added chemicals, has garnered increasing interest in recent years. Through physicochemical means, lignocellulosic material can be pretreated to release monosacharides which can then be upgraded by fermentative and biocatalytic routes. Previous UCL-led research has examined many aspects of utilisation of waste streams from sugar refineries. Vinasse, a glycerol-rich waste product of bioethanol production, was used as a nutrient source for enzyme production. Sugars from SBP, such as D-glucose, L-arabinose and D-galacturonic acid and which make up approximately 25% w/w, 21% w/w, and 20% w/w of the total pulp weight, respectively, were solubilised through operations such as steam explosion pretreatment and depolymerisation of the released polysaccharides. These SBP monosaccharides were then employed in bioconversion reactions using thermostable enzymes. This Thesis aims to study SBP as a feedstock for the enzymatic production of value added chemicals. It also aims to translate key reactions in the valorisation process from batch mode into a continuous flow process in a scalable, 100 mL, Agitated Cell Reactor (ACR). Initial Residence Time Distribution characterisation of the ACR showed that it provided excellent plug flow properties, equivalent to 13 stirred reactors in series. The ACR was able to handle SBP slurries over a range of solids loadings (1% w/v – 5% w/v) and residence times (3.8 min – 19.0 min). The SBP suspension was shown to be shear thinning with measured viscosities in the range of 0.0011 Pa.s at 1% w/v and 0.0339 Pa.s at 10% w/v. A set of correlations was developed that enable prediction of the feed viscosity as a function of SBP concentration and shear rate. The SBP particle size distribution ranged from 15.0 μm (D10) to 446 μm (D90) with a median size of 128 μm. Studies on the particle flow through the ACR demonstrated that steady state could be achieved, but that larger particles had longer residence times than smaller particles through the ACR. Dilute acid pretreatment (DAP) of SBP was investigated as an alternative to previous work on steam explosion as it would be more compatible with continuous operation. DAP using sulfuric acid at concentrations up to 75 mM and 80 °C was performed. These conditions showed good release of polymeric L-arabinose, which increased with higher temperatures and acid concentrations (70% w/w at 75 mM and 80 °C). Cellulose, which is more heat- and acid-resistant than SBP pectin, was only slightly hydrolysed into D-glucose, creating the potential for selective sugar fractionation. When compared to steam explosion pretreatment, flow DAP in the ACR obtained similar throughputs (3.5 and 3.1 g(L-arabinose).hr⁻¹, respectively), but productivity (throughput in terms of reactor volume) was an order of magnitude higher (3.5 and 25.6 g(L-arabinose).L⁻¹.hr⁻¹). Monomerisation of the polymeric L-arabinose could be achieved in a continuous flow enzyme-membrane as in previously described work. Finally, valorisation of the L-arabinose monomers by a continuous-flow, two-step enzymatic process in the ACR was demonstrated. L-gluco-heptulose is a rare ketoheptose which has potential cancer and diabetes treatment applications. The one-pot two-step production of L-gluco-heptulose using a thermostable transaminase (TAm) and transketolase (TK) both isolated from Deinococcus geothermalis DSM11300 was also carried out in the ACR. The initial goal was to use immobilized TK and TAm enzymes in order to intensify the bioconversion process. While TK could be successfully immobilized on both Nickel-chelated beads and Epoxymethacrylate resin, the TAm immobilization proved challenging with only low levels of retained activity. Consequently, the flow studies were performed with soluble TK and TAm enzymes. ACR bioconversions compared favourably with well-mixed batch reactions yields using the same reaction time (2 hours). Initial studies demonstrated the conversion of model substrates L-arabinose, L-serine and α-ketoglutaric acid into L-gluco-heptulose. Subsequently it was shown that L-gluco-heptulose could be synthesised equally well using SBP-derived L-arabinose. Concentrations of the intermediate product hydroxypyruvic acid (HPA) and L-gluco-heptulose obtained in continuous mode were 2.62 mM and 0.60 mM, respectively using SBP derived L-arabinose and 1.21 mM and 0.31 mM, respectively, using model solutes. This was equivalent throughputs of 170.5 µM.hr⁻¹ and 39.0 µM.hr⁻¹ for the SBP derived L-arabinose and 81.0 µM.hr⁻¹ and 20.0 µM.hr⁻¹ for the model solutes. Higher final L-gluco-heptulose concentrations could be obtained by increasing starting L-arabinose concentrations. The continuous process demonstrated here has clear potential for use within a SBP biorefinery. Future work needs to focus on alternative methods of TAm immobilization to enable process intensification and scale-up to pilot scale in order to demonstrate robust commercial operation

ESRDC ship notional baseline Medium Voltage Direct Current (MVDC) architecture thermal simulation and visualization

This work presents a fast visualization and thermal simulation tool developed as part of the Electric Ship Research and Development Consortium (ESRDC) funded by the Office of Naval Research (ONR) that is capable of providing quick responses during early stages of ship design. The tool allows for the visualization of thermal and electrical loads, and equipment locations and other variables of interest in the all-electric ship, proceeding to the computation of the resulting whole ship temperature and relative humidity distribution. For that, a previously developed simplified physical model [1-3] -- which combines principles of classical thermodynamics and heat transfer, resulting in a system of three-dimensional differential equations which are discretized in space using a three-dimensional cell centered finite volume scheme -- is enhanced to include fresh and sea water cooled systems throughout the ship. Therefore, the combination of the proposed simplified physical model with the adopted finite volume scheme for the numerical discretization of the differential equations is called a volume element model (VEM). A 3D simulation is performed in order to determine the temperature distribution inside the ship for the baseline Medium Voltage Direct Current (MVDC) architecture, and representative operating conditions are analyzed. VisIt visualization tool [4] is used to plot the results.United States. Office of Naval Research (Grant N00014-08-1-0080

Une politique concernant les données issues d’un programme de recherches interventionnelles en santé mondiale

ArticleLa recherche interventionnelle en santé mondiale est souvent effectuée au moyen de partenariats scientifiques internationaux. Mais la réalisation de telles recherches, notamment dans les pays à faible revenu où les enjeux de pouvoir, d’argent et de relations interculturelles sont exacerbés, soulève de nombreux défis éthiques, notamment concernant la conduite responsable lors des recherches collaboratives. L’un d’eux est la conservation, l’accès, l’utilisation et la publication des données. Malgré l’existence de multiples politiques et documents phares sur l’éthique et la conduite responsable de la recherche, les chercheurs en recherche interventionnelle sont encore peu outillés pour faire face à ce défi. Dans le contexte d’un programme de recherches interventionnelles réalisées au Burkina Faso, les auteurs souhaitent partager leur expérience dans le développement d’une politique interne concernant leurs données. Après avoir évoqué le contexte global et particulier, l’article présente le processus de formulation et d’adoption de cette politique par les chercheurs d’une équipe interdisciplinaire et internationale (Allemagne, Burkina Faso, Canada, France). Les valeurs qui enchâssent cette politique interne sont la transparence, la prévention, le consensus autour du processus de production, le respect des principes internationaux, l’accès libre aux connaissances produites et la préoccupation pour leur diffusion et utilisation. La politique se présente en plusieurs parties : objet, types et statuts des chercheurs impliqués, conservation des données, accès et utilisation des données, production scientifique et paternité. Les principaux défis rencontrés par les chercheurs pour formuler cette politique sont analysés dans un souci de partage pour susciter un débat rarement abordé. La confiance, la transparence et le respect mutuel doivent être au cœur de tout partenariat scientifique en recherche interventionnelle.Interventional global health research is often carried out through international scientific partnerships. However, the conduct of such research, especially in low-income countries where issues of power, money and intercultural relations are exacerbated, raises many ethical challenges particularly related to responsible conduct in collaborative research. One of these challenges is the storage, access, use and publication of data. Despite the existence of multiple influential policies and documents on ethics and the responsible conduct of research, researchers in intervention research are still not equipped to deal with such challenges. In the context of an intervention research program conducted in Burkina Faso, the authors would like to share their experience in the development of an internal policy concerning their data. After presenting the global and the particular context, the paper presents the process of policy formulation and its adoption by the researchers of an interdisciplinary and international team (Burkina Faso, Canada, France, Germany). The values that entrench this internal policy are: transparency, prevention, consensus about the production process, respect for international principles, free access to the knowledge produced and concerns regarding its dissemination and use. The policy is presented in several parts: aim, types and status of the participating researchers, data storage, access and use of data, scientific production and authorship. The main challenges faced by researchers in formulating this policy are analyzed in a shared desire to spark a debate that is rarely addressed. Trust, transparency and mutual respect should be central to any scientific partnership in intervention research

Candida species biofilms' antifungal resistance

Candida infections (candidiasis) are the most prevalent opportunistic fungal infection on humans and, as such, a major public health problem. In recent decades, candidiasis has been associated to Candida species other than Candida albicans. Moreover, biofilms have been considered the most prevalent growth form of Candida cells and a strong causative agent of the intensification of antifungal resistance. As yet, no specific resistance factor has been identified as the sole responsible for the increased recalcitrance to antifungal agents exhibited by biofilms. Instead, biofilm antifungal resistance is a complex multifactorial phenomenon, which still remains to be fully elucidated and understood. The different mechanisms, which may be responsible for the intrinsic resistance of Candida species biofilms, include the high density of cells within the biofilm, the growth and nutrient limitation, the effects of the biofilm matrix, the presence of persister cells, the antifungal resistance gene expression and the increase of sterols on the membrane of biofilm cells. Thus, this review intends to provide information on the recent advances about Candida species biofilm antifungal resistance and its implication on intensification of the candidiasis.The authors acknowledge the Fundação para a Ciência e Tecnologia (FCT), Portugal, for supporting Maria Elisa Rodrigues (SFRH/BPD/95401/2013) and Célia F. Rodrigues (SFRH/BD/93078/2013). This study was also supported by the Programa Operacional, Fatores de competitividade—COMPETE and by national funds through FCT—Fundação para a Ciência e a Tecnologia under the scope of the projects FCT PTDC/EBB-EBI/120495/2010 and RECI/EBB-EBI/0179/2012 (FCOM-01-0124-FEDER-027462)

Tolerancia de hongos endofíticos septados oscuros a agroquímicos in vitro

Dark septate endophytes (DSE) are a heterogeneous group of fungi, mostly belonging to the Phylum Ascomycota, that are involved in a mutualistic symbiosis with plant roots. The aim of this study is to evaluate the behavior of two strains of DSE isolated from wheat roots of two cropping areas in the province of Buenos Aires, Argentina, against some agrochemicals. Of all the isolates obtained, two strains were identified as Alternaria alternata and Cochliobolus sp. These DSE were found to be tolerant to glyphosate, carbendazim and cypermethrin when evaluated at the recommended agronomic dose (AD), 2 AD and, in some cases, 10 AD. This work contributes to the study of the biology of this group of fungi and their tolerance in the presence of xenobiotics widely used in agriculture.Los endófitos septados oscuros (DSE) son un grupo heterogéneo de hongos que participan de una simbiosis mutualista con raíces de plantas, perteneciendo principalmente al Phylum Ascomycota. El objetivo de este estudio fue aislar DSE de raíces de trigo proveniente de dos áreas de cultivo de la provincia de Buenos Aires y evaluar el comportamiento de dos cepas de DSE aisladas de raíces de trigo frente a algunos agroquímicos en dos áreas de cultivo de la provincia de Buenos Aires. De todos los aislamientos obtenidos se seleccionaron dos cepas que se identificaron como Alternaria alternata y Cochliobolus sp. Se encontró que estos DSE son tolerantes al glifosato, el carbendazim y la cipermetrina, evaluados a las dosis agronómicas recomendadas (AD), a 2x AD y, en algunos casos, a 10x AD. Este trabajo contribuye al conocimiento de la biología de este grupo de hongos y su tolerancia a xenobióticos ampliamente utilizados en la agricultura.Fil: Spagnoletti, Federico Nicolás. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones en Biociencias Agrícolas y Ambientales. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones en Biociencias Agrícolas y Ambientales; Argentina. Universidad de Buenos Aires. Facultad de Agronomía. Departamento de Biología Aplicada y Alimentos. Cátedra de Microbiología Agrícola; ArgentinaFil: Chiocchio, Viviana Monica. Universidad de Buenos Aires. Facultad de Agronomía. Departamento de Biología Aplicada y Alimentos. Cátedra de Microbiología Agrícola; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin