Amener à l'existence : la fragile naissance des nanosystèmes

En partant d'une étude ethnographique dans un laboratoire engagés dans la conception et la réalisation de micro et nanosystèmes, l'article rend compte de la manière dont ces objets sont amenés à l'existence, mais aussi de la fragilité de cette existence d'être technologique. Confronté à de nombreux échecs, les chercheurs en viennent à douter de leur faisabilité technologique, de leur capacité à maintenir l'intérêt des industriels pour ces objets, voire même du sens de l' histoire technologique. Cette histoire, qu' ils croyaient évoluer inéluctablement des microsystèmes vers les nanosystèmes, semble brutalement s'arrêter, voir s'inverser. Les nanosystèmes ne seraient alors qu'un leurre, une illusion plutôt qu'une nouvelle catégorie de technologie. L'existence-même de l'objet est devenue problématique. En suivant les chercheurs, ingénieurs et techniciens au travail, l'article rend compte de la technogénèse comme exploration des modes d'existence des êtres technologiques.

" Laennec CD-ROM " Dix ans d'existence d'un outil multimédia pour l'enseignement des gestes cliniques en pneumologie

Résumé « Laennec CD-ROM » est un programme d'enseignement assisté par ordinateur (EAO) pour l'apprentissage de la sémiologie en pneumologie. Son idée de base était de fournir aux étudiants et aux enseignants un outil d'apprentissage interactif et richement illustré des différents gestes cliniques en pneumologie. Primé en 1994 pour la meilleure contribution multimédia à la European Academie Software Award (EASA-94), il représente un bon exemple de ce qui pouvait être réalisé alors. Mais l'histoire de l'EAO remonte aux années 1960. Un bref historique de l'EAO permet de mieux situer ce programme dans le temps. Et comme tout outil pédagogique, celui-ci s'appuie sur une représentation de comment l'apprentissage se fait. Trois courants pédagogiques majeurs sont présentés. Le behaviorisme ou comportementalisme pour qui le savoir est transmis pour être stocké tel quel par l'apprenant. Pour le cognitivisme, par contre, le contenu est retravaillé par l'apprenant avant d'être stocké, et ce traitement de l'information peut être influencé. Quant au constructivisme, celui-ci prédit que le savoir est construit à l'aide des contenus mis à disposition, mettant en avant l'importance du contexte dans lequel l'apprentissage se fait. Mais indépendamment des orientations pédagogiques, une des question fondamentale est : un enseignement assisté par ordinateur est-il meilleur qu'un enseignement traditionnel ? Étonnamment, il n'est pas facile de répondre à cette question, malgré de . nombreuses études sur le sujet. « Laennec CD-ROM » est constitué de trois parties. Un tutoriel présentant de manière didactique l'inspection, la palpation, la percussion et l'auscultation pulmonaire. Il est richement illustré par des dessins, photos, vidéo et sons d'auscultation. La deuxième partie présente sept patients souffrant de maladies pulmonaires fréquentes. Ce volet du cd-rom permet d'appliquer à des cas les principes de sémiologie appris dans le tutoriel. Pour chaque patient, une anamnèse, un examen clinique (avec des sons d'auscultation) et une série d'examens para-cliniques (imagerie, laboratoire) permettent à l'utilisateur de poser un diagnostic différentiel et un traitement. La troisième partie du cd-rom est un petit historique sur René, Théophile, Hyacinthe Laennec, l'inventeur du stéthoscope. Pour terminer, la conception et la réalisation du programme sont présentées en détail ainsi que sa validation et son utilisation.

Liver hyperplasia and paradoxical regulation of glycogen metabolism and glucose-sensitive gene expression in GLUT2-null hepatocytes. Further evidence for the existence of a membrane-based glucose release pathway.

We investigated the impact of GLUT2 gene inactivation on the regulation of hepatic glucose metabolism during the fed to fast transition. In control and GLUT2-null mice, fasting was accompanied by a approximately 10-fold increase in plasma glucagon to insulin ratio, a similar activation of liver glycogen phosphorylase and inhibition of glycogen synthase and the same elevation in phosphoenolpyruvate carboxykinase and glucose-6-phosphatase mRNAs. In GLUT2-null mice, mobilization of glycogen stores was, however, strongly impaired. This was correlated with glucose-6-phosphate (G6P) levels, which remained at the fed values, indicating an important allosteric stimulation of glycogen synthase by G6P. These G6P levels were also accompanied by a paradoxical elevation of the mRNAs for L-pyruvate kinase. Re-expression of GLUT2 in liver corrected the abnormal regulation of glycogen and L-pyruvate kinase gene expression. Interestingly, GLUT2-null livers were hyperplasic, as revealed by a 40% increase in liver mass and 30% increase in liver DNA content. Together, these data indicate that in the absence of GLUT2, the G6P levels cannot decrease during a fasting period. This may be due to neosynthesized glucose entering the cytosol, being unable to diffuse into the extracellular space, and being phosphorylated back to G6P. Because hepatic glucose production is nevertheless quantitatively normal, glucose produced in the endoplasmic reticulum may also be exported out of the cell through an alternative, membrane traffic-based pathway, as previously reported (Guillam, M.-T., Burcelin, R., and Thorens, B. (1998) Proc. Natl. Acad. Sci. U. S. A. 95, 12317-12321). Therefore, in fasting, GLUT2 is not required for quantitative normal glucose output but is necessary to equilibrate cytosolic glucose with the extracellular space. In the absence of this equilibration, the control of hepatic glucose metabolism by G6P is dominant over that by plasma hormone concentrations.

Early Carboniferous age of the Versoyen ophiolites and consequences: non-existence of a "Valais ocean'' (Lower Penninic, western Alps)

Ophiolites occur at several places in the Lower Penninic of the W and Central Alps. They are generally ascribed to oceanic crust of a so-called ``Valais ocean'' of Cretaceous age which plays a fundamental role in many models of Alpine paleogeography and geodynamics. The type locality and only observational base for the definition of a ``Valais ocean'' in the W Alps is the Versoyen ophiolitic complex, on the French-Italian boundary W of the Petit St-Bernard col. The idea of a "Valais ocean'' is based on two propositions that are since 40 years the basis for most reconstructions of the Lower Penninic: (1) The Versoyen forms the (overturned) stratigraphic base of the Cretaceous-Tertiary Valais-Tarentaise series; and (2) it has a Cretaceous age. We present new field and isotopic data that severely challenge both propositions. (1) The base of the Versoyen ophiolite is a thrust. It overlies a wildflysch with blocks of Versoyen rocks, named the Mechandeur Formation. This ``supra-Tarentaise'' wildflysch has been confused with an (overturned) stratigraphic transition from the Versoyen to the Valais-Tarentaise series. Thus the contact Versoyen/Tarentaise is not stratigraphic but tectonic, and the Versoyen ophiolite has no link with the Valais basin. This thrust corresponds to an inverse metamorphic discontinuity and to an abrupt change in tectonic style. (2) The contact of the Versoyen complex with the overlying Triassic-Jurassic Petit St-Bernard (PSB) series is stratigraphic (and not tectonic as admitted by all authors since 50 years). Several types of sedimentary structures polarize it and show that the PSB series is younger than the Versoyen. Consequently the Versoyen ophiolitic complex is Paleozoic and forms the basement of the PSB Mesozoic sediments. They both belong to a single tectonic unit, named the Versoyen-Petit St-Bernard nappe. (3) Ion microprobe U-Pb isotopic data on zircons from the main gabbroic intrusion in the Versoyen complex give a crystallization age of 337.0 +/- 4.1 Ma (Visean, Early Carboniferous). These zircons show typical oscillatory zoning and no overgrowth or corrosion. and are interpreted to date the Versoyen magmatism. These U-Pb data are in excellent agreement with our field observations and confirm the Paleozoic age of the Versoyen ophiolite. The existence of a ``Valais ocean'' of Cretaceous age in the W Alps becomes very improbable. The eclogite facies metamorphism of the Versoyen-Petit St-Bernard nappe results from an Alpine intra-continental subduction, guided by a Paleozoic oceanic suture. This is an example of the lone term influence of inherited deep-seated structures on a Much younger orogeny. This might well be a major cause of of the inherent complexity of the Alps.

Accumulation des carbohydrates chez les sexués de plusieurs espèces de fourmis en relation avec l'existence ou l'absence d'un vol nuptial

The dispersal strategy of ants generally makes use of a nuptial flight to bring together the sexes. The energy necessary to accomplish this flight comes from stored carbohydrates. However, in some species, one of the sexes does not fly and mating occurs in the nest. This is the case in Iridomyrmex humilis and Cataglyphis cursor, in which the virgin queens possess wings but not leave the natal nest. We show in this work that the winged females of these two species accumulate very little carbohydrate during the maturation period occuring between emergence and mating: expressed as a percentage of dry weight at the time of mating, the total carbohydrates reach only 3.2% in I. humilis and 2.1% in C. cursor. In contrast, the males of these species which fly, possess three to four times more carbohydrates (13.0% and 6.2%, respectively). These latter values are very similar to those found for both sexes of species employing nuptial flights, such several species of wood ants (Formica rufa, F. polyctena, F. lugubris ), Lasius (L. niger , L. flavus ) or Myrmica scabrinodis also studied here. It appears that the absence of the mating flight is associated with reduced levels of carbohydrates, specially glycogen

L'école bouge : un bilan après 3 ans d'existence dans les cantons de Neuchâtel et Vaud

Rapport Baspo

Haut potentiel intellectuel et TDA/H: ressemblances, différences, co-existence ?

Si les particularités du haut potentiel intellectuel (HPI) et du trouble déficit d'attention avec/sans hyperactivité (TDA/H) sont largement décrites dans la littérature, les liens entre ces deux profils sont moins connus. Il est pourtant établi que HPI et TDA/H partagent des manifestations communes comme l'agitation, les difficultés scolaires ou les troubles du comportement. Cette similitude sémiologique est responsable de confusions, d'errance diagnostique, voire de choix thérapeutiques discutables. Et la mission du médecin devient même particulièrement délicate lorsqu'il s'agit d'envisager une éventuelle « co-morbidité ». La clinique nous apprend en effet que le HPI et le TDA/H peuvent cohabiter chez le même enfant. Ainsi, les identifier et les prendre en charge devient un exercice complexe mais indispensable, car l'approche et le soutien de ces enfants aux besoins particuliers est très différente selon les cas de figure.

Affect-related synesthesias: A prospective view on their existence, expression and underlying mechanisms

The literature on developmental synaesthesia has seen numerous sensory combinations, with surprisingly few reports on synaesthesias involving affect. On the one hand, emotion, or more broadly affect, might be of minor importance to the synaesthetic experience (e.g. Sinke et al., 2012). On the other hand, predictions on how affect could be relevant to the synaesthetic experience remain to be formulated, in particular those that are driven by emotion theories. In this theoretical paper, we hypothesize that a priori studies on synaesthesia involving affect will observe the following. Firstly, the synaesthetic experience is not merely about discrete emotion processing or overall valence (positive, negative) but is determined by or even altered through cognitive appraisal processes. Secondly, the synaesthetic experience changes temporarily on a quantitative level according to i) the affective appraisal of the inducing stimulus or ii) the current affective state of the individual. These hypotheses are inferred from previous theoretical and empirical accounts on synaesthesia (including the few examples involving affect), different emotion theories, crossmodal processing accounts in synaesthetes and nonsynaesthetes, and the presumed stability of the synaesthetic experience. We hope that the current review will succeed in launching a new series of studies on "affective synaesthesias". We particularly hope that such studies will apply the same creativity in experimental paradigms as we have seen and still see when assessing and evaluating "traditional" synaesthesias.

Comprehensive spatiotemporal transcriptomic analyses of the ganglionic eminences demonstrate the uniqueness of its caudal subdivision.

The elucidation of mechanisms underlying telencephalic neural development has been limited by the lack of knowledge regarding the molecular and cellular aspects of the ganglionic eminence (GE), an embryonic structure that supplies the brain with diverse sets of GABAergic neurons. Here, we report a comprehensive transcriptomic analysis of this structure including its medial (MGE), lateral (LGE) and caudal (CGE) subdivisions and its temporal dynamics in 12.5 to 16 day-old rat embryos. Surprisingly, comparison across subdivisions showed that CGE gene expression was the most unique providing unbiased genetic evidence for its differentiation from MGE and LGE. The molecular signature of the CGE comprised a large set of genes, including Rwdd3, Cyp26b1, Nr2f2, Egr3, Cpta1, Slit3, and Hod, of which several encode cell signaling and migration molecules such as WNT5A, DOCK9, VSNL1 and PRG1. Temporal analysis of the MGE revealed differential expression of unique sets of cell specification and migration genes, with early expression of Hes1, Lhx2, Ctgf and Mdk, and late enrichment of Olfm3, SerpinE2 and Wdr44. These GE profiles reveal new candidate regulators of spatiotemporally governed GABAergic neuronogenesis.

Direct evidence for the existence of dairying farms in prehistoric Central Europe (4th millennium BC)

The molecular and isotopic chemistry of organic residues from archaeological potsherds was used to obtain further insight into the dietary trends and economies at the Constance lake-shore Neolithic settlements. The archaeological organic residues from the Early Late Neolithic (3922-3902 BC) site Hornstaad-Hornle IA/Germany are, at present, the oldest archaeological samples analysed at the Institute of Mineralogy and Geochemistry of the University of Lausanne. The approach includes 13C/12C and 15N/14N ratios of the bulk organic residues, fatty acids distribution and 13C/12C ratios of individual fatty acids. The results are compared with those obtained from the over 500 years younger Neolithic (3384-3370 BC) settlement of Arbon Bleiche 3/Switzerland and with samples of modern vegetable oils and fat of animals that have been fed exclusively on C3 forage grasses. The overall fatty acid composition (C9 to C24 range, maximizing at C14 and C16), the bulk 13C/12C and 15N/14N ratios (delta13C, delta15N) and the 13C/12C ratios of palmitic (C16:0), stearic (C18:0) and oleic acids (C18:1) of the organic residues indicate that most of the studied samples (25 from 47 samples and 5 from 41 in the delta13C18:0 vs. delta13C16:0 and delta13C18:0 vs. delta13C18:1 diagrams, respectively) from Hornstaad-Hornle IA and Arbon Bleiche 3 sherds contain fat residues of pre-industrial ruminant milk, and young suckling calf/lamb adipose. These data provide direct proof of milk and meat (mainly from young suckling calves) consumption and farming practices for a sustainable dairying in Neolithic villages in central Europe around 4000 BC.dagger