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Hydroxyapatite crystal thickness and orientation at the bone implant interface : spatial and temporal evolutions
No full textInternational audienceBone structure is complex and evolves over time, especially during osseointegration, when bone forms around and onto an implant surface. Sufficient bone ingrowth together with adequate quality, depending on its compositional, structural and mechanical properties, will condition the long-term stability of the implant. The nanoscale arrangement and reorganization is of particular interest since a relationship between mineralcrystals thickness and elastic properties of bone tissue has been observed [1]. Thus, characterizing crystal thickness around an implant may help to evaluate the mechanical properties of the interface. but only little work is available [2, 3]. We investigated spatial and temporal evolutions of crystal thickness and orientation close to a metallic implant using small angle x-ray scattering (SAXS); this work has been published [4]
Se faire bénévole et faire corps. Mener l’enquête dans les territoires de l’intendance écologique citoyenne en ville
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A modified magnetic bottle electron spectrometer for the detection of multiply charged ions in coincidence with all correlated electrons: decay pathways to Xe 3+ above xenon-4d ionization threshold
No full textInternational audienceNew magnet design of a magnetic bottle electron spectrometer allowing the detection of multiply charged ions in coincidence with n electrons. Electrons spectra obtained without and with filtering by coincidence with Xe n + ions
Climate aridity and habitat drive geographical variation in morphology and thermo-hydroregulation strategies of a widespread lizard species
No full textInternational audienceThermo-hydroregulation strategies involve concurrent changes in functional traits related to energy, water balance and thermoregulation and play a key role in determining life-history traits and population demography of terrestrial ectotherms. Local thermal and hydric conditions should be important drivers of the geographical variation of thermo-hydroregulation strategies, but we lack studies that examine these changes across climatic gradients in different habitat types. Here, we investigated intraspecific variation of morphology and thermo-hydroregulation traits in the widespread European common lizard (Zootoca vivipara louislantzi) across a multidimensional environmental gradient involving independent variation in air temperature and rainfall and differences in habitat features (access to free-standing water and forest cover). We sampled adult males for morphology, resting metabolic rate, total and cutaneous evaporative water loss and thermal preferences in 15 populations from the rear to the leading edge of the distribution across an elevational gradient ranging from sea level to 1750 m. Besides a decrease in adult body size with increasing environmental temperatures, we found little effect of thermal conditions on thermo-hydroregulation strategies. In particular, relict lowland populations from the warm rear edge showed no specific ecophysiological adaptations. Instead, body mass, body condition and resting metabolic rate were positively associated with a rainfall gradient, while forest cover and water access in the habitat throughout the season also influenced cutaneous evaporative water loss. Our study emphasizes the importance of rainfall and habitat features rather than thermal conditions for geographical variation in lizard morphology and physiology
Semiotic Approaches in Science Didactics
No full textInternational audienceThe sciences are, in essence, highly semiotized. Our ways of thinking and communicating about science are based on permanent transformations from one system of signs to another, such as scriptural, graphic, symbolic, oral and gestural signs. The semiotic focus studied in this book makes it possible to grasp part of the complexity of teaching and learning phenomena by focusing on the variety of possible interpretations of the signs that circulate within the science classroom. Semiotic Approaches in Science Didactics brings together contributions from didactic research involving various disciplines such as mathematics, chemistry, physics and geography, which mobilize different types of semiotic support. It offers the key to understanding and even reducing some of the misunderstandings that can arise between a speaker and a receiver in scientific teaching situation
Multispecies allometric equations for shrubs and trees biomass prediction in a Guinean savanna (West Africa)
No full textInternational audienceHighlights • New allometric equations were developed for predicting aboveground and belowground biomass (AGB and BGB) of trees and multi-stemmed shrubs in the Guinean savannas based on field measurements, providing information for West African mesic savannas and filling a critical knowledge gap. • AGB and BGB of trees were better predicted from the quantity ρD b 2 H (with ρ the specific wood density in g cm-3 , D b the stem basal diameter in cm, and H the tree height in m). • Obtaining accurate estimates of AGB and BGB in multi-stemmed shrubs required additional consideration of the total number of stems. • The root/shoot biomass ratio decreased with increasing of the stem size (measured by D b) for trees but remains relatively unchanged for shrubs
3Worlds, a simulation platform for ecosystem modelling
No full textInternational audienceEcology, like many disciplines, commonly relies on simulation to provide insights into the dynamics of complex systems. Yet there are two unresolved problems for ecological studies relying on simulation. First, it is often the case that simulators representing the same system, designed for ostensibly the same purpose, differ in their results with the reasons buried deep within computer code. Second, ecology is a diverse discipline and each subdiscipline necessarily has its particular simulation methods. This raises a problem as to how models from these various fields can be coupled for transdisciplinary studies. We built a new simulation platform named 3Worlds, grounded on a concept familiar and common to all fields of ecology: the ecosystem. We defined the ecosystem for the purpose of simulation by a precise set of rules. The platform can implement models from fields as diverse as food web, population and landscape ecology, energy and material stocks and fluxes, and techniques such as agent-based, cellular automata and discrete-event simulation. In addition, we developed a dynamic graph to represent ecosystems as a set of interacting components. Our approach goes some way to unifying ecology for the purpose of simulation and reduces the problem of code comparison to a comparison of two graphs: (1) a specification graph that complies with the rules of what constitutes an ecosystem, and (2) the successive graph states of a particular simulation trajectory representing the ecosystem. Two applications constitute the core of 3Worlds. ModelMaker builds the ecosystem compliant model and ModelRunner executes the model represented as a dynamic graph. A library of ~24 models illustrates how 3Worlds can simulate very different systems, from simple 1-equation 1-variable models to individual-based systems with thousands of ecosystem components
Du cas Schreber et de ce qu’on ne doit pas oser faire dans l’éducation : une contribution au débat sur la transmission
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De l’inaptitude au capacitaire en EPS : discussion autour d’un environnement scolaire capacitant
No full textInternational audienceIn school and PE, a semantic field of infirmity and anormality (Mazereau, 2012; Stiker, 2013; Roca, 1992) crossed the last century in France, especially to questioning the nature of the physical abilities of the pupils. In addition, a reading of the body in action is structured from a reference to the medical model of disability, leaving less regard to any pupils other than the "able-bodied". Historically speaking, what has been the evolution of this relationship to the medical field? Can we consider that the school space and the PE have been privileged spaces for structuring an enabling environment (Falzon, 2005), in particular for pupils with disabilities? The capacitaire (Paintendre, 2017) questions adaptation of the person to his environment through the emergence of new possibilities to act (Paintendre & Andrieu, 2015). This person adjusts her bodily possibilities from her sensory experience to move from capability (Sen, 2009) to capacity. A new look is posed on the relationship (Rosa, 2020) between the pupil and his environment which becomes empowering rather than handicapping, in order to structure a training path where each pupil becomes a partially able pupil and not a disabled pupil.À l’école et en EPS, un verbiage du registre de l’infirmité et de l’anormalité (Mazereau, 2012 ; Stiker, 2013 ; Roca, 1992) a traversé le siècle dernier lorsqu’il s’agissait de s’interroger sur la nature des aptitudes corporelles des élèves. De surcroît, une lecture du corps en action s’est structurée à partir d’une référence au modèle « médical » du handicap ne laissant que peu de crédit à tout autre élève que le « valide sportif ». Historiquement, quelle a été l’évolution de ce rapport au milieu « médical » ? Peut-on considérer que l’espace scolaire et l’EPS ont été des espaces privilégiés pour structurer un environnement capacitant (Falzon, 2005), notamment pour les élèves en situation de handicap ? Le capacitaire (Paintendre, 2017) questionne l’adaptation de la personne à son environnement par l’émersion de nouvelles possibilités d’agir (Paintendre & Andrieu, 2015). Elle ajuste ses possibilités corporelles à partir de son expérience sensorielle pour passer de la capabilité (Sen, 2009) à la capacité. Un regard nouveau se pose sur la relation (Rosa, 2020) entre l’élève et son environnement où ce dernier peut devenir progressivement capacitant plutôt qu’handicapant, afin de structurer un parcours de formation où chaque élève devient un élève apte partiel et non un élève in-capable
