Les ressources numériques, de quoi parle-t-on ?

Quelques définitions Les ressources numériques dans cet ouvrage La notion de « ressource numérique » convoque un certain nombre d’images fortement contrastées en fonction de la profession et de la culture du locuteur ; elle est aussi très marquée dans le temps. Car, littéralement, une ressource numérique est un ensemble de moyens représentés par des chiffres, exploitables grâce à l’outil informatique. Rien de plus vague qu’une pareille notion. Il serait d’ailleurs plus exact de parler d’infor..

Mode d’emploi

Depuis déjà plusieurs années, les bibliothèques s'interrogent sur leur avenir, leurs missions, parfois même sur leur pertinence à l'heure où l'accès à l’information et à la culture s’opère de plus en plus sous forme dématérialisée. Si l'objet-livre a fondé la bibliothèque en tant que lieu, les bibliothèques ont déjà fait la preuve de leur capacité à intégrer d'autres documents, d'autres supports, d'autres vecteurs d'information et de culture que le livre. De nouvelles ressources dématérialisé..

Mémento

À travers les différentes contributions de cet ouvrage, c’est la mise en place d’une véritable méthodologie de projet qui se dessine pour une intégration réussie des ressources numériques dans les collections de la bibliothèque. En amont du projet Connaître le contexte La connaissance du contexte local et national est désormais incontournable tant le numérique est au cœur de stratégies de mutualisation. La politique numérique des établissements s’inscrit en effet dans des politiques plus glob..

Intégrer des ressources numériques dans les collections

Cet ouvrage s’inscrit dans la continuité de plusieurs autres volumes de la collection afin de proposer aux bibliothécaires et documentalistes des clés pour aborder et gérer efficacement la documentation dématérialisée : une douzaine d’auteurs s’attachent à présenter les modalités de sélection, d’acquisition, de signalement, d’évaluation et de conservation propres à ces ressources en développant en filigrane un questionnement sur la fonction de la bibliothèque. Prenant appui aussi bien sur des bibliothèques de lecture publique que des universités, le plan s’organise autour de quatre parties pragmatiques et opératoires : connaître le contexte ; sélectionner et acquérir ; intégrer et sélectionner et, enfin, évaluer et conserver. Géraldine Barron et Pauline Le Goff-Janton sont conservatrices des bibliothèques

Optical chirality without optical activity: How surface plasmons give a twist to light

Light interacts differently with left and right handed three dimensional chiral objects, like helices, and this leads to the phenomenon known as optical activity. Here, by applying a polarization tomography, we show experimentally, for the first time in the visible domain, that chirality has a different optical manifestation for twisted planar nanostructured metallic objects acting as isolated chiral metaobjects. Our analysis demonstrate how surface plasmons, which are lossy bidimensional electromagnetic waves propagating on top of the structure, can delocalize light information in the just precise way for giving rise to this subtle effect.Comment: Opt. Express 16, 12559 (2008

From Fischer projections to quantum mechanics of tetrahedral molecules: new perspectives in chirality

The algebraic structure of central molecular chirality can be achieved starting from the geometrical representation of bonds of tetrahedral molecules, as complex numbers in polar form, and the empirical Fischer projections used in organic chemistry. A general orthogonal O(4) algebra is derived from which we obtain a chirality index related to the classification of a molecule as achiral, diastereoisomer or enantiomer. Consequently, the chiral features of tetrahedral chains can be predicted by means of a molecular Aufbau. Moreover, a consistent Schroedinger equation is developed, whose solutions are the bonds of tetrahedral molecules in complex number representation. Starting from this result, the O(4) algebra can be considered as a quantum chiral algebra. It is shown that the operators of such an algebra preserve the parity of the whole system.Comment: 33 pages, to appear in Adv. Quantum Che

Dilution of seawater affects the Ca2 + transport in the outer mantle epithelium of crassostrea gigas

Varying salinities of coastal waters are likely to affect the physiology and ion transport capabilities of calcifying marine organisms such as bivalves. To investigate the physiological effect of decreased environmental salinity in bivalves, adult oysters (Crassostrea gigas) were exposed for 14 days to 50% seawater (14) and the effects on mantle ion transport, electrophysiology and the expression of Ca2+ transporters and channels relative to animals maintained in full strength sea water (28) was evaluated. Exposure of oysters to a salinity of 14 decreased the active mantle transepithelial ion transport and specifically affected Ca2+ transfer. Gene expression of the Na+/K+-ATPase and the sarco(endo)plasmic reticulum Ca2+-ATPase was decreased whereas the expression of the T-type voltage-gated Ca channel and the Na+/Ca2+-exchanger increased compared to animals maintained in full SW. The results indicate that decreased environmental salinities will most likely affect not only osmoregulation but also bivalve biomineralization and shell formation.Funding Agency European Union (EU) 605051 Swedish Mariculture Research Center, SWEMARC, University of Gothenburg Herbert & Karin Jacobssons Stiftelse 15/h17 Helge Ax:son Johnsons Stiftelse F18-0128 Portuguese Foundation for Science and Technology UID/Multi/04326/2019 Portuguese Foundation for Science and Technology UID/Multi/04326/2019 FCT, under the "Norma Transitoria" DL57/2016/CP1361/CT0020 DL57/2016/CP1361/CT0011info:eu-repo/semantics/publishedVersio

Emergent dynamic chirality in a thermally driven artificial spin ratchet

Modern nanofabrication techniques have opened the possibility to create novel functional materials, whose properties transcend those of their constituent elements. In particular, tuning the magnetostatic interactions in geometrically frustrated arrangements of nanoelements called artificial spin ice1, 2 can lead to specific collective behaviour3, including emergent magnetic monopoles4, 5, charge screening6, 7 and transport8, 9, as well as magnonic response10, 11, 12. Here, we demonstrate a spin-ice-based active material in which energy is converted into unidirectional dynamics. Using X-ray photoemission electron microscopy we show that the collective rotation of the average magnetization proceeds in a unique sense during thermal relaxation. Our simulations demonstrate that this emergent chiral behaviour is driven by the topology of the magnetostatic field at the edges of the nanomagnet array, resulting in an asymmetric energy landscape. In addition, a bias field can be used to modify the sense of rotation of the average magnetization. This opens the possibility of implementing a magnetic Brownian ratchet13, 14, which may find applications in novel nanoscale devices, such as magnetic nanomotors, actuators, sensors or memory cells

Biotic soil-plant interaction processes explain most of hysteretic soil CO2 efux response to temperature in cross-factorial mesocosm experiment

Ecosystem carbon fux partitioning is strongly infuenced by poorly constrained soil CO2 efux (Fsoil). Simple model applications (Arrhenius and Q10) do not account for observed diel hysteresis between Fsoil and soil temperature. How this hysteresis emerges and how it will respond to variation in vegetation or soil moisture remains unknown. We used an ecosystem-level experimental system to independently control potential abiotic and biotic drivers of the Fsoil-T hysteresis. We hypothesized a principally biological cause for the hysteresis. Alternatively, Fsoil hysteresis is primarily driven by thermal convection through the soil profle. We conducted experiments under normal, fuctuating diurnal soil temperatures and under conditions where we held soil temperature near constant. We found (i) signifcant and nearly equal amplitudes of hysteresis regardless of soil temperature regime, and (ii) the amplitude of hysteresis was most closely tied to baseline rates of Fsoil, which were mostly driven by photosynthetic rates. Together, these fndings suggest a more biologically-driven mechanism associated with photosynthate transport in yielding the observed patterns of soil CO2 efux being out of sync with soil temperature. These fndings should be considered on future partitioning models of ecosystem respiration.French governmentFrench National Research Agency (ANR) ANR-10-IDEX-0001-02 PSL ANR-11-INBS-0001ENSUniversity of Arizona (UofA)Philecology Foundation (Fort Worth, Texas, USA)Thomas R. Brown Family FoundationRegion Ile-de-France I-05-098/R 2011-11017735European Union (EU)National Science Foundation (NSF) 1417101 1331408European Union (EU) 625988UofA Office of Global InitiativesOffice of the Vice President of Research at the UofAUMI iGLOBES program at the Uof