ICTs and innovation in teaching practices in Cameroon

Cet article étudie l’innovation technologique dans les pratiques enseignantes au Cameroun. Il rend ainsi compte des pratiques techno-pédagogiques, à partir de l’examen d’une série de 84 entrevues menées avec des enseignants issus de sept établissements pilotes d’intégration pédagogique des TIC. Dans ce contexte, l’innovation s’intègre davantage dans la recherche documentaire et la préparation des cours. Les autres tâches techno-pédagogiques apparaissent alors minoritaires. De façon générale, considérées comme outils pédagogiques, les TIC n’occupent pas encore une place centrale en enseignement-apprentissage dans ce contexte. Cela pose alors la question de l’équipement technologique des écoles et de la formation techno-pédagogique des enseignants dans une perspective qui allie à la fois diffusion, adoption et appropriation des technologies

Role of substrate outgassing on the formation dynamics of either hydrophilic or hydrophobic wood surfaces in atmospheric-pressure, organosilicon plasmas

This work examines the influence of substrate outgassing on the deposition dynamics of either hydrophilic or hydrophobic coatings on wood surfaces in organosilicon, dielectric barrier discharges. Sugar maple and black spruce wood samples were placed on the bottom electrode and the discharge was sustained in N2–HMDSO (hexamethyldisiloxane) gas mixtures by applying a 24 kV peak-to-peak voltage at 2 kHz. Current–voltage characteristics revealed a transition from a filamentary to a homogeneous discharge with increasing plasma treatment time, t. Based on opticalemission spectroscopy, the filamentary behaviorwas ascribed to the release of air and humidity from the wood substrate following discharge exposure which produced significant quenching of N2 metastables. This effect vanished at longer treatment times due to the nearly complete “pumping” of products from the wood substrate and the progressive deposition of a “barrier” layer. Analysis of the surface wettability through static, water contact angles (WCAs) and of the surface composition through Fourier-Transform-Infra-Red-Spectroscopy and X-ray-Photoelectron-Spectroscopy indicated that for t b 10 min, the wood surface was more hydrophilic due to the formation of a SiOx layer, a typical behavior for HMDSO deposition in presence of oxygen. On the other hand, for t > 10 min, the static WCA increased up to ~140° due to the deposition of hydrophobic Si(CH3)3-O-Si(CH3)2, Si(CH3)3, and Si(CH3)2 functional groups

Mutarotational Kinetics and Glass Transition of Lactose

We report for the first time real time in situ and quantitative measurements of the mutarotation reaction of lactose in the solid state. The experiments have been performed by 13C NMR. We show that mutarotation is initiated on heating the amorphous state, and reaches chemical equilibrium close above the glass transition temperature Tg. We do not observe this transformation when starting from stable crystalline states. The final ratio of and anomers is 1:1, which suggests that the energy profile of the mutarotation reaction pathway in the solid state is actually different from the mechanism proposed for aqueous solution. This chemical equipartition is reached before the crystallization into the corresponding 1:1 molecular compound. These new data clearly illustrate the interrelation between the chemical molecular properties, the physical state of the material, and the relaxational dynamics of the glass

Respostas de enzimas antioxidantes a bioativador em plântulas de milho sob estresse hídrico.

Edição Especial contendo os Anais do XVIII Congresso Brasileiro de Sementes, Florianópolis, set. 2013

Qualidade fisiológica de sementes de soja tratadas durante o armazenamento.

Edição Especial contendo os Anais do XVIII Congresso Brasileiro de Sementes, Florianópolis, set. 2013

XXXI. Collections in foreign geology .—[No. III.]

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Social representations and uses of computer technology by pupils in two secondary schools of Cameroon. Outline of an approach to the use of technology and techno-school innovation

RésuméCette thèse étudie comment les élèves des lycées Général Leclerc et bilingue de Yaoundé (Cameroun) s’approprient l’ordinateur et l’intègrent dans leur univers sociocognitif et quotidien. Pour y arriver, elle examine à la fois ce que ces sujets font effectivement avec cette technologie et ce qu’ils en pensent socialement. Sur cette base, elle esquisse une approche de l’appropriation des technologies et de l’innovation techno-scolaire. La question qui a servi de guide est celle-ci : Comment ces élèves s’approprient-ils l’ordinateur, et dans quelle mesure l’étude combinée des usages et des représentations sociales qu’ils y construisent, contribue-t-elle à saisir cette appropriation et à approcher l’innovation technologique à l’école ? L’hypothèse générale que nous avons posée est que cette appropriation de l’ordinateur est multiforme, et comporte des aspects partagés mais aussi différenciés selon les différentes catégories sociales des répondants et selon les divers contextes d’utilisation de cet outil. Étudiée en prenant en compte usages et représentations, elle révèle cette technologie dans ses dimensions technique, scolaire, sociocognitif et symbolique. Cette démarche est alors capable de renseigner sur les formes et significations de l’appropriation, mais aussi sur son contenu, son organisation et sa conception comme un champ symbolique de positionnement des acteurs, ce qui permet d’approcher l’appropriation des technologies, mais aussi leur implémentation à l’école.Au plan théorique, plusieurs approches ont été mobilisées pour conduire la vérification de cette hypothèse. Nous avons ainsi retenu l’approche de l’appropriation pour étudier les usages de l’ordinateur. Nous avons aussi utilisé le courant des représentations sociales en faisant appel au modèle qui intègre la théorie du noyau central et celle des principes organisateurs. Du côté de la méthodologie, nous avons opté pour une démarche qualitative qui laisse place à l’exploitation des données quantitatives et à la prise en compte des paroles et pratiques des acteurs. Aussi avons-nous retenu les techniques de recherche fondées sur l’expression discursive et pratique des sujets : l’interview, le réseau d’associations et l’observation directe. Les deux premières ont été administrées à un groupe de 64 élèves choisis sur la base de leur genre, cycle d’études et familiarité avec l’ordinateur. La dernière quant à elle a été menée dans des salles de classe, centres de ressources multimédias, cours de récréation et cybercafés. Si l’interview a porté sur tous les aspects de l’objet étudié, le réseau d’associations et l’observation directe quant à eux ont respectivement concerné les représentations sociales et les usages de l’ordinateur chez les répondants.L’analyse des données recueillies confirme les hypothèses de recherche. La thèse montre en effet une variété d’usages contextualisés, différenciés et signifiés. Aussi, face aux diverses contraintes, les élèves exploitent les éléments contextuels pour imaginer des stratégies de détournement, ce qui permet de souligner l’image d’un acteur qui bien que contraint par le système, fait dans et avec ce système pour s’approprier l’innovation techno-scolaire. Ce travail présente aussi un champ représentationnel de l’ordinateur dense et varié. Dans ce champ, l’ordinateur apparaît sous plusieurs angles : physique, scolaire, communicationnel, ludique, extraordinaire, mystérieux, positif et négatif. L’étude de sa structure montre que pour ces élèves, l’ordinateur est fondamentalement un objet technologique qui sert principalement à faire des recherches et à communiquer. Autour de ces enjeux, s’organisent des prises de position ancrées dans des réalités qui relèvent du genre, de la familiarité avec l’ordinateur et/ou du niveau scolaire. L’un des enseignements tirés de cette démarche qui intègre usages et représentations sociaux d’une technologie, est qu’elle renseigne non seulement sur l’épaisseur sociale de l’usage qui est le lieu de formation de l’appropriation, mais aussi sur le contenu, la structuration et les orientations de cette appropriation. Elle permet aussi de considérer cette appropriation comme un champ symbolique dans lequel les usagers de cette technologie se positionnent en fonction de leur capital informatique. En envisageant l’appropriation des technologies à la fois en termes d’usages et de représentations sociales, cette démarche permet aussi de penser une approche globale et participative de leur intégration à l’école.AbstractThis thesis focusses on how pupils in the General Leclerc and bilingual secondary school in Yaoundé (in Cameroon) appropriate computer technology and integrate this into their daily and socio-cognitive environment. In order to do this, the study examines both what the subjects actually do with this technology and what they think of it socially. On this basis, the study outlines an approach of the appropriation of technology and of techno-school innovation. The following question served as a guide: How do the learners concerned appropriate computer technology, and to what extent does the combined study of the uses and social representations they share on this technology, contribute to understand this appropriation and to approach technological innovation in school? The general hypothesis we have put forward is that this appropriation of computer technology is multifaceted, and involves some collective but also some very distinct aspects according to the different social categories of the subjects concerned and to the various contexts of use of this technology. By taking account of uses and representations, the study of this appropriation reveals this technology in its technical, educational, socio-cognitive and symbolic dimensions. This approach provides information about the forms and meanings of the technological appropriation, but also on its content, organization and conception as a symbolic field in which users position. This makes it possible to approach the appropriation of technologies and their implementation in school.Several theoretical approaches were used to examine this hypothesis. We adopted the approach of appropriation in order to study the use of computers. We also used social representation theory by referring to the model which integrates central core theory and principles of organisational theory. With regard to methodology, we opted for a qualitative approach while using quantitative data and paying particular attention to the words and practices of the respondents. We also used research techniques based on the discursive and practical expression of individuals: interview, association-network and direct observation. The first two of these techniques were administered to a group of 64 pupils who were chosen according to their gender, study cycle and familiarity with computers. The observation technique was conducted in the classrooms, multimedia resource centres, recreation classes and internet cafés. While the interview concentrated on all aspects of the subject studied, the association-network and direct observation methods concerned respectively the study of uses and social representations of computer. Analysis of the data gathered confirmed the research hypotheses. The thesis shows a variety of contextualized, differentiated and signified uses. Also, when faced with the different constraints, the pupils used contextual elements to imagine misappropriation strategies. Although constrained by the system, they act with and within this system in order to appropriate techno-school innovation. This work also presents a dense and varied representational field of computer technology. Within this field, computer technology is seen from different angles: physical, educational, communicational, recreational, extraordinary, mysterious, positive and negative. The study of the structure of this social representation shows that for these pupils, the computer is fundamentally a technological object which is principally used for research and communication purposes. One valuable piece of information that has been learned from this approach that integrates the uses and social representations of a technology, is that it provides information not only about the social dimension of the use and appropriation, but also about the content and structuring of this appropriation. This approach also makes it possible to consider this appropriation as a symbolic field in which the users of the technology interact according to their cultural capital. By considering the appropriation of technologies both in terms of uses and social representations, this approach also makes it possible to work out a global and participative approach of their integration into the school system

Habitat filtering determines spatial variation of macroinvertebrate community traits in northern headwater streams

Although our knowledge of the spatial distribution of stream organisms has been increasing rapidly in the last decades, there is still little consensus about trait-based variability of macroinvertebrate communities within and between catchments in near-pristine systems. Our aim was to examine the taxonomic and trait based stability vs. variability of stream macroinvertebrates in three high-latitude catchments in Finland. The collected taxa were assigned to unique trait combinations (UTCs) using biological traits. We found that only a single or a highly limited number of taxa formed a single UTC, suggesting a low degree of redundancy. Our analyses revealed significant differences in the environmental conditions of the streams among the three catchments. Linear models, rarefaction curves and beta-diversity measures showed that the catchments differed in both alpha and beta diversity. Taxon- and trait-based multivariate analyses also indicated that the three catchments were significantly different in terms of macroinvertebrate communities. All these findings suggest that habitat filtering, i.e., environmental differences among catchments, determines the variability of macroinvertebrate communities, thereby contributing to the significant biological differences among the catchments. The main implications of our study is that the sensitivity of trait-based analyses to natural environmental variation should be carefully incorporated in the assessment of environmental degradation, and that further studies are needed for a deeper understanding of trait-based community patterns across near-pristine streams

Caracteres agronômicos e fisiológicos associados ao progresso do melhoramento genético de trigo no Brasil

Knowledge the processes responsible for the progress of genetic gain in grain yield in wheat plant is an essential step for the development of high yield cultivars. The aims of the study were: a) Evaluate the duration of developmental phases in wheat cultivars and quantify the importance of each phase on grain yield and its components. b) characterize physiological and agronomically wheat cultivars released in different decades, to identify selection criteria for continued improvement of genetic progress in Brazil. c) Characterize Brazilian wheat cultivars developed in different decades for the nitrogen use efficiency (NUE). Ten wheat cultivars released from1940 to 2009, were examined for two years in a competition essay (2010 and 2011) and in 2011 an essay in green house was conducted with four nitrogen rates (0, 60, 120 e 180 kg N ha-1). We compared the duration of periods, agronomic and physiological traits (gas exchange) and nitrogen use efficiency (EUN) characters. The Breeding reduced time to anthesis and increased the grain filling, contributing to the increase in thousand kernel weight. The modern cultivars had the period terminal spikelet to anthesis increased (0,68 to 1,35 degree days year-1) over the years, contributing to the increase in the number of grains per spikelet, number of grains per spike, spike dry weight at anthesis and spike fertility index. The increase in grain yield was 29 kg ha-1 yr-1, with a genetic gain of 0,92% yr-1 from 1940 to 2009, this is largely related to the increased of harvest index, number of grains m-2 and biological yield, which were achieved through improving stomatal conductance and photosynthetic rate in pre and post-anthesis and reduced in plant height. The nitrogen uptake efficiency (NUpE) was positively associated with nitrogen use efficiency (NUE) in the absence of fertilization. Nitrogen utilization efficiency (NutE) and NUpE were positively associated with NUE in higher N. The modern cultivars (Quartzo, CD 117, BRS Tangará, BRS 220, BRS 208 and BRS Guamirim) were more efficient in the use of nitrogen and more tolerant to low N input compared to the group formed by BRS 179, BR 23, Toropi and Frontana.CNPqConhecer os processos responsáveis pelo avanço do progresso genético do rendimento de grãos é uma etapa essencial para o desenvolvimento de cultivares mais produtivas. Os objetivos do estudo foram: a) Avaliar a duração dos subperíodos de desenvolvimento de cultivares de trigo brasileiros, lançados entre 1940 e 2009, e quantificar a importância de cada fenofase sobre o rendimento de grãos e seus componentes. b) Caracterizar, fisiologica e agronomicamente, cultivares de trigo desenvolvidos entre 1940 e 2009, a fim de identificar critérios de seleção mais efetivos à continuidade do progresso genético de melhoramento no Brasil. c) Caracterizar cultivares antigos e modernos brasileiros, lançados em diferentes décadas, quanto à eficiência do uso do nitrogênio e seus componentes. Dez cultivares de trigo brasileiros, antigos e modernos, foram avaliados em ensaios de competição, em duas safras agrícolas (2010 e 2011); na safra agrícola de 2011 um ensaio foi conduzido em casa de vegetação, com quatro doses de nitrogênio (0, 60, 120 e 180 kg N ha-1). Comparou-se a duração dos subperíodos, caracteres agronômicos e fisiológicos (trocas gasosas) e caracteres da eficiência do uso do nitrogênio (EUN). O melhoramento reduziu a fase de semeadura a antese e aumentou a fase de enchimento de grãos, contribuindo com o aumento da massa de mil grãos. Os genótipos modernos tiveram o subperíodo de espigueta terminal a antese aumentado (0,68 a 1,35 graus dias ano-1) ao longo dos anos, contribuindo com o incremento do número de grãos por espigueta, número de grãos por espiga, peso seco de espiga em antese e índice de fertilidade da espiga. O incremento de rendimento de grãos foi de 29 kg ha-1 ano-1, com um ganho genético de 0,92% ano-1 no período de 1940 e 2009. O progresso genético para rendimento de grãos foi principalmente relacionado ao incremente do índice de colheita, número de grãos e rendimento biológico, que foram alcançados pelo aumento da condutância estomática e da taxa fotossintética em pré e pós-antese e redução da estatura de planta. A eficiência de absorção de nitrogênio (EAN) foi positivamente associada com a eficiência do uso do nitrogenio (EUN) na ausência de adubação nitrogenada. A eficiência de utilização do nitrogenio (EUtN) e a EAN foram positivamente associadas a EUN nas doses elevadas de N. Os cultivares mais recentemente disponibilizados para cultivo (Quartzo, CD 117, BRS Tangará, BRS 220, BRS 208 e BRS Guamirim) foram mais eficientes no uso do nitrogênio e mais tolerantes a baixas doses em comparação ao grupo formado pelos cultivares BRS 179, BR 23, Toropi e Frontana