Characterization of surface layers on individual marine CaCO₃ particles, using "variable energy" electron probe microanalysis (poster)

The ocean constitutes a large sink for anthropogenic CO2, and thus plays a significant role in the global biogeochemical cycle of carbon and its perturbations. There remain, however, large uncertainties concerning the uptake of anthropogenic carbon by the ocean, mainly due to insufficient knowledge of processes controlling the pCO2 in surface waters. Most of the previous research efforts have been concentrated on the study of CO2 exchange at the air-sea interface due to temperature effects related to the general circulation of water masses or to the biological activity in terms of new production of organic matter and export to deep waters. The effect of precipitation of calcium carbonate by calcifying organisms in the euphotic zone and the redissolution of their skeletons has not been fully taken into account yet. This precipitation-dissolution process affects both the concentration of dissolved inorganic carbon (DIC) and alkalinity and plays thus a significant role in the buffering capacity of seawater and its potential to act as a sink or a source of CO2 for the atmosphere. Quantification of the processes affecting the inorganic carbon cycle is fundamental, not only for the understanding of the present day situation, but also for the predictive studies in the context of global warming. The anthropogenic CO2 can be transferred into or out of the ocean via air-sea exchange as a result of various processes. They include dissolution of CO2 (g) in seawater, photosynthesis and respiration, and precipitation of carbonate particles. During photosynthesis, CaCO3 is precipitated and this carbonate sinks out of the surface layer along with the exported organic carbon. The calcification process modifies the dissolved inorganic carbonate system according to the following reaction:Ca2+ + 2HCO3- CaCO3 + CO2 (g) + H2OThe production of CaCO3 will thus consume alkalinity, increase pCO2 and reduce total DIC in the surface layer of the ocean, driving CO2 from the ocean to the atmosphere.We aim to study the processes associated with the oceanic production and dissolution of CaCO3 in order to quantify the role of calcifying phytoplanktonic organisms in sequestering CO2.Electron probe microanalysis (EPMA) was used for characterization of individual particles for their composition, morphology and dissolution features. Most attention is paid to the concentration of Mg and Sr in CaCO3 particles, because of their effect on the solubility of carbonates and because of the fact that they are characteristic for their origin. In June 2001, a mesocosm experiment: “Biological responses to CO2 - related changes in seawater carbonate chemistry during a bloom of Emiliana huxleyi” was set up at the Large Scale Facility for Marine Pelagic Food Chain Research, University of Bergen, Bergen, Norway. Three different pCO2’s (200 ppm, 380 ppm, 700 ppm) were generated in different mesocosms where cultures were grown. Organisms from each of these cultures were analysed using optimised low-Z EPMA technology to examine the difference in calcification. “Variable-energy” EPMA was applied for the characterization of surface layers of the CaCO3-scales of Emiliana huxleyi

Atmospheric nitrogen input into the North Sea: organic nutrient detection

The levels of gaseous organic nitrogen compounds (alkyl nitrates - ANs) together with identification of the possible sources of these compounds in the air were studied. Seasonal trends were investigated by conducting the sampling campaigns during the spring, summer and winter time. The air-mass backward trajectories (BWTs) were calculated for the sampling periods by Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) model (Draxler and Rolph, 2003). These BWTs were considered for the determination of the influence of the Atlantic Ocean, the North Sea and the continent as possible sources of ANs. An adapted set-up for low and high volume samplings, extraction and minimized clean-up, identification and quantification capabilities resulting from the complementary use of GC-ECD and GC-MS methods is reported. The AN levels were found to be in the range of a few to 7400 pg.m-3 in the air. The AN fraction consisted of primarily the 2C4, C5 and C6 isomers, which contribute largely to the total AN level. The N-fluxes by ANs were more pronounced for the summer periods than for the winter/spring months, organic nitrates were the most abundant in the Atlantic/Channel/UK air-masses

Le "travail curriculaire" des enseignants en éducation physique : du travail prescrit au travail réel

Recherche financée par la CAPES - Brésil.Dans cette recherche de doctorat, nous analysons le « travail curriculaire » des enseignants en éducation physique. Le travail curriculaire est l’ensemble des processus d’interprétation, d’adaptation et de transformation du curriculum prescrit par les enseignants pour le rendre enseignable aux élèves (Tardif et Lessard, 1999). En 2012, il y a eu la mise en œuvre du curriculum municipal d’éducation physique (CMÉP) pour les écoles municipales de Cuiabá (Moreira, 2012), dans l’État du Mato Grosso, au Brésil. Cependant, on en savait très peu sur comment les enseignants l’intègrent à leurs enseignements en salle de classe. En ce sens, notre question de recherche est : comment les enseignants interprètent-ils et transforment-ils le curriculum prescrit en salle de classe? Autrement dit, comment réalisent-ils le travail curriculaire? Concernant notre cadre théorique, il s’appuie sur la sociologie du travail enseignant et sur l’ergonomie française, plus particulièrement sur l’approche de la clinique de l’activité. Notre recherche est mixte, mais avec un accent plus fort placé sur la perspective qualitative. En outre, l’étude peut être classifiée comme une recherche-intervention selon l’approche historico-développementale. Dans la première phase, nous avons administré un questionnaire à 73 enseignants pour connaître leurs perceptions à l’égard du CMÉP et du programme de formation continue qui a été offert pour appuyer l’implantation du curriculum. Dans la deuxième phase, nous avons mené une étude multi-cas avec quatre enseignants, trois femmes et un homme, dont deux étaient novices (E1 et E2) et deux étaient expérimentés (E3 et E4). Nous avons consulté des documents (le curriculum prescrit, les projets pédagogiques des écoles, les planifications des enseignants) et nous avons fait des entrevues semi- dirigées au début de la recherche et à la fin de l’année scolaire 2015. De plus, nous avons observé et tourné des vidéos de leurs leçons pendant une période de deux mois. Ensuite, nous avons appliqué la méthode de l’autoconfrontation simple et croisée (Clot, 2008), où nous avons pu accéder aux points de vue sur les activités en salle de classe des enseignants participants à l’étude multi-cas. Parmi les principaux résultats de notre recherche, nous pouvons souligner que : concernant la perception générale positive du CMÉP, 82,19% des enseignants trouvent qu’il est avantageux d’enseigner conformément au CMÉP. Par rapport à l’usage du CMÉP, presque 80% des enseignants utilisent toujours ou presque toujours ce curriculum pour faire leurs planifications annuelles, 76,72% en font l’usage pour planifier leurs séances, et 72,61% l’utilisent en l’adaptant. En ce qui a trait aux aspects qui entravent l’implantation du CMÉP, le manque de matériel iv pédagogique (41,1%) et les installations inadéquates (34,25%) sont les facteurs qui empêchent le plus la mise en œuvre du curriculum. Par rapport à la formation continue, 74% des enseignants estiment qu’elle offre l’appui suffisant pour l’implantation du CMÉP et qu’elle a été fonctionnelle pour presque 90% des enseignants. Par rapport aux résultats de l’étude multi-cas, nous soulignons que : les enseignants utilisent le CMÉP pour faire leurs planifications annuelles, à moyen ou court termes, mais ils l’interprètent, l’adaptent et le transforment lors de l’enseignement en classe avec leurs élèves, chacun à sa façon et selon leurs connaissances de la matière, du curriculum et des élèves, des ressources et des espaces disponibles, mais en les transformant et en les adaptant ceux- ci aussi. En bref, les facteurs contextuels et personnels du travail curriculaire influent sur cette adaptation du curriculum. De plus, notre étude a montré que les enseignants sont des interprètes, acteurs, auteurs et constructeurs du curriculum d’éducation physique enseigné en classe et que les élèves sont co-auteurs des leçons avec leurs enseignants.In this doctoral thesis, we are going to analyze the curricular work of teachers in physical education. The curricular work is the sum of all processes of interpretation, adaptation and transformation by the teachers of the prescribed curriculum to make it teachable to students (Tardif & Lessard, 1999). In 2012, the physical education municipal curriculum (PEMC) was implemented for every municipal schools of Cuiabá, in the state of Mato Grosso, Brazil. However, little was known about the way teachers would integrate this curriculum in their teaching in the classroom. Consequently, our research question is: how do teachers interpret and transform the prescribed curriculum in their classroom? In other words, how do they implement the curriculum? Regarding our theoretical framework, it relies on the sociology of teaching work and on French ergonomics, more specifically the approach of the activity clinic. This is a mixed research, with a stronger accent put on the qualitative perspective. Furthermore, this memoir can be categorized as a research-intervention in accordance with the historical-developmental approach. In the first phase, we distributed a questionnaire to 73 teachers to learn about their perceptions of the PEMC and the professional training they received to implement the curriculum. In the second phase, we conducted a multi- cases study with four teachers – three women and one man. Two of them were novice teachers (T1 and T2) and the other two were experienced (T3 and T4). We consulted documents (the prescribed curriculum, the schools’ educational projects, the teachers’ school planning) and we conducted semi-directed interviews at the start and at the end of the 2015 school year. In addition, we filmed class lessons for a period of two months. During the multi-cases study, we also used the single and crossed self-confrontation method, where we could examine different point of views about the teachers’ activities in the classroom. Of all the major results of the research, we can highlight that: concerning the general perception of the PEMC which was positive, 82.19% of the teachers found it advantageous to teach according to it; concerning the use of the PEMC, almost 80% of the teachers always or almost always use the curriculum to build their yearly school planning, 76.72% use it to plan their classes and 72.61% adapt it before using it. Regarding the obstacles for the implementation of the PEMC, the lack of educational material (41.1%) and inadequate infrastructures (34.25%) are the factors that most prevent the curriculum implementation. Concerning the professional training, 74% of the teachers found it sufficient for the implementation of the PEMC and that it was functional for almost 90% of them. As for the results of the multi- vi cases study, we would like to point out that: the teachers use the PEMC to build their yearly planning, in the long or short term, but they interpret it, adapt it and transform it during teaching in the classroom, in their own way and depending on the knowledge they have of the lessons content, of the curriculum and of the students, the resources and locations available, but always by transforming and adapting it also. In short, the contextual and personal factors of the curricular work influence that adaptation of the curriculum. Also, our study showed that the teachers are interprets, actors, authors and builders of the physical education curriculum taught in class and that the students are co-authors of the lessons with their teachers

Efeito residual do herbicida Kifix® nas culturas de arroz, feijão e sorgo.

As culturas produzidas nos dias atuais necessitam cada vez mais de herbicidas eficazes para o manejo e controle de plantas daninhas nos mais diversos sistemas produtivos integrados. Portanto, torna-se necessário soluções inovadoras que possibilitam o aumento da produtividade com pouco impacto ao agroecossistema. Nesse sentido, este trabalho objetivou determinar o efeito residual do herbicida Kifix® (Imazapir 525 g.kg-1 + Imazapique 175 g.kg-1) em solos de um sistema de integração lavoura pecuária.Apresentação oral - graduação

Efeitos da substituíção da gordura do leite por gordura de soja no crescimento de bezerros.

A gordura hidrogenada de soja possibilitou um desenvolvimento corporal dos bezerros semelhantes ao conseguido atraves da gordura do leite

Diffractive Contribution to the Elasticity and the Nucleonic Flux in the Atmosphere

We calculate the average elasticity considering non-diffractive and single diffractive interactions and perform an analysis of the cosmic-ray flux by means of an analytical solution for the nucleonic diffusion equation. We show that the diffractive contribution is important for the adequate description of the nucleonic and hadronic fluxes in the atmosphere.Comment: 10 pages, latex, 2 figures (uuencoded PostScript

Tribo-rheology and sensory analysis of a dairy semi-solid

Tribology science is devoted on explaining the friction behavior of interacting surfaces in relative motion. Several tribological systems have been used to measure coefficient of friction (CoF) vs sliding speed of entrained food layer between two rubbing surfaces. These results can be correlated with fat-related attributes perceived during oral processing. This study aims to investigate the effect of starch, carrageenan and fat on the friction profile; flow behavior and particle size distribution. Friction curves were obtained for custards using a tribo-rheometer with a rotating metallic geometry rubbing the surface of 3 M tape with roughness similar to that depicted by human tongue. Confocal Laser Scanning Microscopy (CLSM) images of custard collected during friction experiment helped to explain the characteristics of tribological regimes. As expected, fat-containing samples depicted remarkably lower CoF than skim compositions (fat: 0.2 < CoF < 0.08 and skim: 0.6 < Co

Molecular composition of organic aerosols in central Amazonia: An ultra-high-resolution mass spectrometry study

The Amazon Basin plays key role in atmospheric chemistry, biodiversity and climate change. In this study we applied nanoelectrospray (nanoESI) ultra-high-resolution mass spectrometry (UHRMS) for the analysis of the organic fraction of PM$_{2.5}$ aerosol samples collected during dry and wet seasons at a site in central Amazonia receiving background air masses, biomass burning and urban pollution. Comprehensive mass spectral data evaluation methods (e.g. Kendrick mass defect, Van Krevelen diagrams, carbon oxidation state and aromaticity equivalent) were used to identify compound classes and mass distributions of the detected species. Nitrogen-and/or sulfur-containing organic species contributed up to 60% of the total identified number of formulae. A large number of molecular formulae in organic aerosol (OA) were attributed to later-generation nitrogen-and sulfur-containing oxidation products, suggesting that OA composition is affected by biomass burning and other, potentially anthropogenic, sources. Isoprene-derived organosulfate (IEPOX-OS) was found to be the most dominant ion in most of the analysed samples and strongly followed the concentration trends of the gas-phase anthropogenic tracers confirming its mixed anthropogenic-biogenic origin. The presence of oxidised aromatic and nitro-aromatic compounds in the samples suggested a strong influence from biomass burning especially during the dry period. Aerosol samples from the dry period and under enhanced biomass burning conditions contained a large number of molecules with high carbon oxidation state and an increased number of aromatic compounds compared to that from the wet period. The results of this work demonstrate that the studied site is influenced not only by biogenic emissions from the forest but also by biomass burning and potentially other anthropogenic emissions from the neighbouring urban environments.Research at the University of Cambridge was supported by European Research Council grant no. 279405. The authors would like to thank Jason Surratt (University of North Carolina) for providing a synthesised IEPOX-OS standard. O3, CO, NOy , RH and rain data were obtained from the Atmospheric Radiation Measurement (ARM) Climate Research Facility, a U.S. Department of Energy (grant DE-SC0011122) Office of Science user facility sponsored by the Office of Biological and Environmental Research. We acknowledge the support from the Central Office of the Large Scale Biosphere Atmosphere Experiment in Amazonia (LBA), the Instituto Nacional de Pesquisas da Amazonia (INPA), and the Universidade do Estado do Amazonia (UEA). The work was conducted under 001030/2012-4 of the Brazilian National Council for Scientific and Technological Development (CNPq)

Molecular composition of organic aerosols in central Amazonia: An ultra-high-resolution mass spectrometry study

The Amazon Basin plays key role in atmospheric chemistry, biodiversity and climate change. In this study we applied nanoelectrospray (nanoESI) ultra-high-resolution mass spectrometry (UHRMS) for the analysis of the organic fraction of PM$_{2.5}$ aerosol samples collected during dry and wet seasons at a site in central Amazonia receiving background air masses, biomass burning and urban pollution. Comprehensive mass spectral data evaluation methods (e.g. Kendrick mass defect, Van Krevelen diagrams, carbon oxidation state and aromaticity equivalent) were used to identify compound classes and mass distributions of the detected species. Nitrogen-and/or sulfur-containing organic species contributed up to 60% of the total identified number of formulae. A large number of molecular formulae in organic aerosol (OA) were attributed to later-generation nitrogen-and sulfur-containing oxidation products, suggesting that OA composition is affected by biomass burning and other, potentially anthropogenic, sources. Isoprene-derived organosulfate (IEPOX-OS) was found to be the most dominant ion in most of the analysed samples and strongly followed the concentration trends of the gas-phase anthropogenic tracers confirming its mixed anthropogenic-biogenic origin. The presence of oxidised aromatic and nitro-aromatic compounds in the samples suggested a strong influence from biomass burning especially during the dry period. Aerosol samples from the dry period and under enhanced biomass burning conditions contained a large number of molecules with high carbon oxidation state and an increased number of aromatic compounds compared to that from the wet period. The results of this work demonstrate that the studied site is influenced not only by biogenic emissions from the forest but also by biomass burning and potentially other anthropogenic emissions from the neighbouring urban environments.Research at the University of Cambridge was supported by European Research Council grant no. 279405. The authors would like to thank Jason Surratt (University of North Carolina) for providing a synthesised IEPOX-OS standard. O3, CO, NOy , RH and rain data were obtained from the Atmospheric Radiation Measurement (ARM) Climate Research Facility, a U.S. Department of Energy (grant DE-SC0011122) Office of Science user facility sponsored by the Office of Biological and Environmental Research. We acknowledge the support from the Central Office of the Large Scale Biosphere Atmosphere Experiment in Amazonia (LBA), the Instituto Nacional de Pesquisas da Amazonia (INPA), and the Universidade do Estado do Amazonia (UEA). The work was conducted under 001030/2012-4 of the Brazilian National Council for Scientific and Technological Development (CNPq)