Persistent enhancement of the carrier density in electron irradiated InAs nanowires

We report a significant and persistent enhancement of the conductivity in free-standing non intentionnaly doped InAs nanowires upon irradiation in ultra high vacuum. Combining four-point probe transport measurements performed on nanowires with different surface chemistries, field-effect based measurements and numerical simulations of the electron density, the change of the conductivity is found to be caused by the increase of the surface free carrier concentration. Although an electron beam of a few keV, typically used for the inspection and the processing of materials, propagates through the entire nanowire cross-section, we demonstrate that the nanowire electrical properties are predominantly affected by radiation-induced defects occuring at the nanowire surface and not in the bulk.Comment: 18 pages, 5 figure

Concevoir des contenus de formations des enseignants à partir de l'analyse du système d'activité en classe

Cette communication présente une réflexion relative à la conception de formations issues de l'analyse de l'activité en classe. Les résultats d'une étude portant sur une séquence de lecture orale et collective au Cycle 2 du primaire montrent que l'action de l'enseignante et des élèves s'articulent localement et que ces articulations font émerger une organisation collective que nous dénommons configuration d'activité. Cette configuration est organisée au sens où un ordre émerge de ces interactions locales, et organisante dans la mesure où les actions individuelles sont contraintes par elle en retour. La discussion porte sur la possibilité de concevoir des contenus de formation d'enseignants sur l'analyse de l'activité réelle en classe, et notamment sur le (ou les) niveau(x) d'organisation de l'activité pertinent(s) pour la conception de ces contenus

Farming in mediterranean France and rural settlement in the Late Roman and early Medieval periods : the contribution from archaeology and environmental sciences in the last twenty years

International audienceInterdisciplinary synthesis interweaving diverse sources (archeological data, bioarcheological data, environnemetal data....) trying to answer the question : evolution or revolution between the Roman World and the Early medieval periodespecially for rural word in Southern FranceEssai de sythèse interdisplinaire posant au travers du croisement de données archéologiques, bioarchéologiques et environnementales la question de la continuité entre le monde romain et le haut Moyen Âge pour le monde rural de la France méridionale

Beneficial influence of nanocarbon on the aryliminopyridylnickel chloride catalyzed ethylene polymerization

A series of 1-aryliminoethylpyridine ligands (L1―L3) was synthesized by condensation of 2-acetylpyridine with 1-aminonaphthalene, 2-aminoanthracene or 1-aminopyrene, respectively. Reaction with nickel dichloride afforded the corresponding nickel (II) chloride complexes (Ni1–Ni3). All compounds were fully characterized and the molecular structures of Ni1 and Ni3 are reported. Upon activation with methylaluminoxane (MAO), all nickel complexes exhibit high activities for ethylene polymerization, producing waxes of low molecular weight and narrow polydispersity. The presence of multi-walled carbon nanotubes (MWCNTs) or few layer graphene (FLG) in the catalytic medium can lead to an increase of productivity associated to a modification of the polymer structure

TbAGO1, an Argonaute protein required for RNA interference, is involved in mitosis and chromosome segregation in Trypanosoma brucei

BACKGROUND: RNA silencing processes are widespread in almost all eukaryotic organisms. They have various functions including genome protection, and the control of gene expression, development and heterochromatin formation. RNA interference (RNAi) is the post-transcriptional destruction of RNA, which is mediated by a ribonucleoprotein complex that contains, among several components, RNA helicases and Argonaute proteins. RNAi is functional in trypanosomes, protozoan parasites that separated very early from the main eukaryotic lineage and exhibit several intriguing features in terms of the control of gene expression. In this report, we investigated the functions of RNAi in Trypanosoma brucei. RESULTS: By searching through genome databases, novel Argonaute-like proteins were identified in several protozoa that belong to the kinetoplastid order, a group of organisms that diverged early from the main eukaryotic lineage. T. brucei possesses two Argonaute-like genes termed TbAGO1 and TbPWI1. Dual transient transfection assays suggest that TbAGO1, but not TbPWI1, is involved in RNAi. The entire coding region of TbAGO1 was deleted by double gene knockout. TbAGO1-/- cells turned out to be completely resistant to RNAi generated either by transfected double-stranded RNA or by expression of an inverted repeat. TbAGO1-/- cells were viable but showed a dramatically reduced growth rate. This was probably due to defects in mitosis and abnormal chromosome segregation as revealed by in situ analysis. The RNAi and growth phenotypes were complemented by the inducible expression of a GFP::TbAGO1 fusion protein that revealed the cytoplasmic location of the protein. CONCLUSIONS: The requirement of TbAGO1 for RNAi in trypanosomes demonstrates the evolutionary ancient involvement of Argonaute proteins in RNAi silencing processes. RNAi-deficient TbAGO1-/- cells showed numerous defects in chromosome segregation and mitotic spindle assembly. We propose a working hypothesis in which RNAi would be involved in heterochromatin formation at the centromere and therefore in chromosome segregation

Gender differences in hospital mortality and use of percutaneous coronary intervention in acute myocardial infarction : microsimulation analysis of the 1999 nationwide french hospitals database.

Background— Women with acute myocardial infarction have a higher hospital mortality rate than men. This difference has been ascribed to their older age, more frequent comorbidities, and less frequent use of revascularization. The aim of this study is to assess these factors in relation to excess mortality in women. Methods and Results— All hospital admissions in France with a discharge diagnosis of acute myocardial infarction were extracted from the national payment database. Logistic regression on mortality was performed for age, comorbidities, and coronary interventions. Nonparametric microsimulation models estimated the percutaneous coronary intervention and mortality rates that women would experience if they were "treated like men." Data were analyzed from 74 389 patients hospitalized with acute myocardial infarction, 30.0% of whom were women. Women were older (75 versus 63 years of age; Pacute myocardial infarction gender; revascularization; mortality;