199 research outputs found
Chemical weathering of a granitic watershed: coupling Lithium isotopes and reactive transport modeling, preliminary results.
International audienceIn the present study, we report lithium concentrations and Li isotopic compositions for different samples within a granitic watershed (Margeride, France). We investigate unweathered bedrock and samples displaying different stages of weathering in order to characterize Li isotopic fractionation. This was achieved by coupling lithium isotope geochemistry and reactive transport modeling during granite weathering at the scale of this watershed. The following manuscript reports methodology and the preliminary data
« Thinking outside of the box » : rĂ©flexion sur lâacceptabilitĂ© en anglais lingua franca professionnelle
Le concept de locuteur-allocutaire idĂ©al dĂ©veloppĂ© par Noam Chomksy (1965) et la place centrale quâoccupent les variĂ©tĂ©s natives de lâanglais sur la carte mentale du monde anglophone de Braj Kachru (1985) impliquent que la compĂ©tence en anglais devrait ĂȘtre calquĂ©e sur celle des locuteurs nĂ©s du « bon cĂŽté » de la carte et apprenant lâanglais « depuis le berceau ». Cette conception de la compĂ©tence est problĂ©matique dans les milieux professionnels oĂč lâanglais est souvent une lingua franca, acquise par expĂ©rience dans le cadre spĂ©cialisĂ© du mĂ©tier des employĂ©s. Alors que les Ă©carts par rapport Ă lâanglais dit « standard » sont frĂ©quemment constatĂ©s et peuvent ĂȘtre considĂ©rĂ©s comme inacceptables vis-Ă -vis de la norme native, les Ă©tudes de terrain montrent quâils ne troublent pas le cours normal des actions. Il sâensuit que, du moins dans le contexte professionnel, le modĂšle chomskyen de la compĂ©tence et la place centrale des natifs par rapport Ă la norme doivent ĂȘtre reconsidĂ©rĂ©s. Dans cet article, nous proposons un modĂšle de maĂźtrise de lâanglais comme lingua franca professionnelle fondĂ© sur le concept dâutilisateur global et expĂ©rimentĂ© dâune langue anglaise acquise au sein des rĂ©seaux socio-professionnels internationaux. Ce modĂšle sert de point dâappui pour lâidentification de trois critĂšres dâacceptabilitĂ© qui, dâaprĂšs notre observation des courriers Ă©lectroniques professionnels, contribuent trĂšs largement Ă la rĂ©ussite des interactions dans ce domaine. Enfin, cette rĂ©flexion nous amĂšne Ă mesurer les incidences que peut avoir un tel modĂšle au niveau pĂ©dagogique oĂč le niveau de compĂ©tence du locuteur natif reste, pour la plupart des institutions, lâobjectif Ă atteindre.The ideal speaker-listener concept developed by Noam Chomsky (1965) and the central position given to the native varieties of English on Braj Kachruâs mental map of the English-speaking world largely imply that a competence model in English should derive from the speakers who were born on the âright sideâ of the map and who learnt English âfrom the cradleâ. However, as far as workplace interactions are concerned, the very notion of competence is problematic since English is very often a lingua franca acquired in the course of specialised, professional actions. Although many non-standard usages may be observed and considered unacceptable according to the native norms, field work increasingly shows that they do not impede the normal course of actions. This means that the chomskyan competence model and the central position occupied by native speakers should be reconsidered, at least as far as workplace interactions are concerned. In this article, we introduce a proficiency model based on global, experienced users of the English language involved in international, socio-professional networks. We use this model to identify three acceptability criteria which, according to our observation of professional emails, largely contribute to the success of interactions in this type of situation. Such a paradigm shift naturally leads us to consider some pedagogical implications for French institutions where native skills still form the basis of the teaching framework
Normal modes and long period seismograms in a 3D anelastic elliptical rotating Earth
International audienceWe present results of a direct method to compute realistic long period (>200 s in this example) synthetic seismograms using higher order perturbation theory (up to the 3rd order). Normal modes are computed for the Earth, taking into account rotation, ellipticity, 3D elastic lateral heterogeneities (SAW12D) for the whole mantle, and anelastic lateral variations in the upper mantle (QR19). Coupling between different modes and branches is included in the computation. We study the sensitivity of the waveform to 3D anelasticity and the biases between 3D elastic and 3D anelastic variations. The resulting seismograms can be computed to higher frequency and may then be used to perform whole mantle joint inversions for elastic and anelastic structure
Pierre Frath, José Carlos Herreras (dir.), Plurilinguisme et créativité scientifique
« Les partisans du plurilinguisme ont encore du pain sur la plancheâŠÂ ». Cette phrase est la derniĂšre dâun ouvrage tout Ă fait bienvenu Ă lâheure oĂč lâenseignement-apprentissage des langues fait lâobjet de nombreux discours de façade dans les Ă©tablissements de lâenseignement supĂ©rieur et de la recherche et oĂč les actions rĂ©ellement favorables au dĂ©veloppement du plurilinguisme font, il faut bien lâavouer, plutĂŽt dĂ©faut. Le plurilinguisme est ici envisagĂ© non pas dans une problĂ©matique dâensemb..
La confidentialité dans les courriers électroniques professionnels
Les Ă©changes de courriels en entreprise relĂšvent du domaine privĂ© et, Ă ce titre, sont tous confidentiels. Ă partir d'un corpus constituĂ© en 2007, cet article propose une observation de la confidentialitĂ© dans les Ă©changes en anglais issus de dix entreprises situĂ©es en France. Une nouvelle dĂ©finition des courriels professionnels est proposĂ©e. La confidentialitĂ© est ensuite envisagĂ©e comme une caractĂ©ristique centrale dans les Ă©changes. Cette confidentialitĂ©, issue du partage des secrets dâinitiĂ©s, semble alors indiquer que les courriels professionnels vĂ©hiculent des genres « occlus » en anglais de spĂ©cialitĂ©.As corporate email exchanges belong to the private domain, they are all confidential. Based on a corpus constructed in 2007, the article aims at observing confidentiality in the emails in English from ten companies located in France. First, a new definition of corporate emails is proposed. Confidentiality is then studied as a central feature in the exchanges. This confidentiality, being the result of âinsideâ secrets, suggests that corporate emails serve as a channel for âoccludedâ genres in English for Specific Purposes.
Boron Isotope Characterization to Design a Frame of Hydrogeological Functioning of a Wetland System (Massif Central, France)
AbstractMulti-isotopic approaches (Li, Sr, O, H), combined with hydrological tools, have been already appliedfor tracing the water and dissolved-element fluxes in a peatland in Central France. Here, we applied B isotopes. The ÎŽ11B ratios increase from river draining basalts (⌠0â°) up to springs bordering the peatland (>+25â°). Peatland groundwaters have intermediate ÎŽ11B: 7.8 to 19.4â°. This range is accompanied by an increase in the Ca contents between the river draining basalts and water in the peatland. In aÎŽ11B vs.Ca/B diagram, the role of water rock interaction and present day fertilizer inputs is evidenced, as for Sr isotopes
Lithium isotopes in low and high temperature hydrosystems
International audienceAssessing the origin and behaviour of lithium and the distribution of Li isotopes in hydro-systems is of major importance in order to increase our knowledge of the lithium cycling at the Earth's surface. Lithium is a fluid-mobile element and due to the large relative mass difference between its two stable isotopes, it is subject to significant low and high temperature mass fractionation which provides key information on the nature of water/rock interaction processes. The main objective of the present work is to constrain the behaviour of Li and its isotopes by focusing on three different hydrosystems: rainwaters, river waters and deep geothermal waters
Nouveaux systÚmes de contrÎle de la polarisation de la lumiÚre par effets non linéaires dans les fibres optiques
Ce mĂ©moire prĂ©sente les travaux effectuĂ©s sur le dĂ©veloppement d un dispositif tout-optique de contrĂŽle de l Ă©tat de polarisation de la lumiĂšre, appelĂ© attracteur de polarisation. En effet, cette caractĂ©ristique de la lumiĂšre demeure une variable incontrĂŽlable qui peut dĂ©grader les performances des dispositifs tout-optiques. BasĂ© sur l interaction non linĂ©aire entre deux ondes contrapropagatives au sein d une fibre optique, ce dispositif permet de contrĂŽler l Ă©tat de polarisation de la lumiĂšre sans pertes dĂ©pendantes de la polarisation.Il est tout d abord effectuĂ© une Ă©tude approfondie des propriĂ©tĂ©s de l attracteur de polarisation qui conduit au contrĂŽle et Ă la stabilisation de l Ă©tat de polarisation d un flux de donnĂ©es optiques aux formats NRZ et RZ cadencĂ© Ă 10 Gb/s dans des fibres de plusieurs kilomĂštres. Par la suite, cette fonction de rĂ©gĂ©nĂ©ration tout-optique est associĂ©e Ă d autres fonctions de rĂ©gĂ©nĂ©ration telles que l amplification Raman et le rĂ©gĂ©nĂ©rateur de Mamyshev dans le but de rĂ©gĂ©nĂ©rer des flux de donnĂ©es optiques Ă des dĂ©bits supĂ©rieurs Ă 10 Gb/s.Enfin, une extension de l attracteur de polarisation, appelĂ© Omnipolariseur, est Ă©tudiĂ©e oĂč la lumiĂšre interagit avec elle-mĂȘme grĂące Ă un dispositif de rĂ©flexion insĂ©rĂ© Ă l autre extrĂ©mitĂ© de la fibre optique. La lumiĂšre est alors capable d auto-organiser son Ă©tat de polarisation, ce qui dĂ©montre la capacitĂ© de l Omnipolariseur par exemple Ă stabiliser l Ă©tat de polarisation d un flux de donnĂ©es optiques RZ Ă 40 Gb/s Ă 1550 nmThis thesis deals with the work the development of an all-optical device for the control of the polarization state of light. Actually, this feature of light remains so far an uncontrolled variable, which can degrade the performances of all-optical systems. Based on nonlinear interaction between two counterpropagating waves inside an optical fiber, this device called polarization attractor allows to control the polarization state of light without polarization dependent losses.In a first part, we carry out extensive studies of the polarization attractor properties leading to the control and the regeneration of the polarization state of the 10-Gb/s NRZ and RZ telecommunication signals. Then, this all-optical regeneration function is associated with other regeneration functions, like Raman amplification and Mamyshev regenerator, in order to regenerate optical telecommunication signals at rates exceeding 10-Gb/s.Finally, we present an extension of polarization attractor, called Omnipolarizer, where the light interacts with herself by means of a reflective element inserted at the opposite end of the optical fiber. In that case, the light is able to organize its own polarization state, demonstrating the ability of Omnipolarizer to stabilize by example the polarization state of a 40-Gb/s RZ telecommunication signal at 1550 nmDIJON-BU Doc.Ă©lectronique (212319901) / SudocSudocFranceF
Time course analysis of RNA stability in human placenta
<p>Abstract</p> <p>Background</p> <p>Evaluation of RNA quality is essential for gene expression analysis, as the presence of degraded samples may influence the interpretation of expression levels. Particularly, qRT-PCR data can be affected by RNA integrity and stability. To explore systematically how RNA quality affects qRT-PCR assay performance, a set of human placenta RNA samples was generated by two protocols handlings of fresh tissue over a progressive time course of 4 days. Protocol A consists of a direct transfer of tissue into RNA-stabilizing solution (RNAlaterâą) solution. Protocol B uses a dissection of placenta villosities before bio banking. We tested and compared RNA yields, total RNA integrity, mRNA integrity and stability in these two protocols according to the duration of storage.</p> <p>Results</p> <p>A long time tissue storage had little effect on the total RNA and mRNA integrity but induced changes in the transcript levels of stress-responsive genes as TNF-alpha or COX2 after 48 h. The loss of the RNA integrity was higher in the placental tissues that underwent a dissection before RNA processing by comparison with those transferred directly into RNA laterâą solution. That loss is moderate, with average RIN (RNA Integration Numbers) range values of 4.5â6.05, in comparison with values of 6.44â7.22 in samples directly transferred to RNAlaterâą (protocol A). Among the house keeping genes tested, the B2M is the most stable.</p> <p>Conclusion</p> <p>This study shows that placental samples can be stored at + 4°C up to 48 h before RNA extraction without altering RNA quality. Rapid tissue handling without dissection and using RNA-stabilizing solution (RNAlaterâą) is a prerequisite to obtain suitable RNA integrity and stability.</p
Optical Dark Rogue Wave
Photonics enables to develop simple lab experiments that mimic water rogue wave generation phenomena, as well as relativistic gravitational effects such as event horizons, gravitational lensing and Hawking radiation. The basis for analog gravity experiments is light propagation through an effective moving medium obtained via the nonlinear response of the material. So far, analogue gravity kinematics was reproduced in scalar optical wave propagation test models. Multimode and spatiotemporal nonlinear interactions exhibit a rich spectrum of excitations, which may substantially expand the range of rogue wave phenomena, and lead to novel space-time analogies, for example with multi-particle interactions. By injecting two colliding and modulated pumps with orthogonal states of polarization in a randomly birefringent telecommunication optical fiber, we provide the first experimental demonstration of an optical dark rogue wave. We also introduce the concept of multi-component analog gravity, whereby localized spatiotemporal horizons are associated with the dark rogue wave solution of the two-component nonlinear Schrödinger system
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