Functional Maps of Neocortical Local Circuitry

This review aims to summarize data obtained with different techniques to provide a functional map of the local circuit connections made by neocortical neurones, a reference for those interested in cortical circuitry and the numerical information required by those wishing to model the circuit. A brief description of the main techniques used to study circuitry is followed by outline descriptions of the major classes of neocortical excitatory and inhibitory neurones and the connections that each layer makes with other cortical and subcortical regions. Maps summarizing the projection patterns of each class of neurone within the local circuit and tables of the properties of these local circuit connections are provided

LETEC (Learning and Teaching Corpus) Simuligne

Learning and Teaching Corpus of the online educational experiment Simuligne (2001). Its scenario is based on a global simulation for the learning of French as a foreign language. It also includes an intercultural activity, "Interculture", based on the Cultura project. The corpus includes the pedagogical scenario, described in several formats, the research protocol, participant's online interactions and productions (structured in XML), list of participants, licences of use.\ud The LETEC corpus associated (mce.simu.all.all-CP.zip) is organized as an IMS-CP archive. We define a Learning & Teaching Corpus as a structured entity containing all the elements resulting from a communicative on-line learning situation, whose context is described by an educational scenario and a research protocol. The core data collection includes all the interaction data, the productions of the course participants, and the tracks, resulting from the participants’ actions in the learning environment and stored according to the research protocol. In order to be able to be shared, and to respect participant privacy, these data should be anonymised and a license for its use be provided in the corpus. A derived analysis can be linked to a given set of data under consideration, used or computerized for this analysis. An analysis consisting in data annotation/transcription/transformation, accurately connected to its original data, can be merged with the corpus itself, in order for other researchers to compare their own results on a concurrent analysis or to build their complementary analysis upon these results.\ud The definition of a Learning & Teaching Corpus as a whole entity comes from the need of explicit links, between interaction data, context and analyses. This explicit context is crucial for an external researcher to interpret the data and to perform its own analyses.\ud This definition seeks to capture the context of the data stemming from the course in order to allow a researcher to look for, understand and connect this information whether or not he/she was involved in the original course. More details about a LETEC corpus an ist structure at : http://mulce.univ-fcomte.fr/metadata/LETECorpus-en.pd

The use of Lorentz microscopy for the determination of magnetic reversal mechanism of exchange-biased Co30Fe70/NiMn bilayer

Lorentz transmission electron microscopy (LTEM) combined with in-situ magnetizing experiments is a powerful tool for the investigation of the magnetization of the reversal process at the micron scale. We have implemented this tool on a conventional transmission electron microscope (TEM) to study the exchange anisotropy of a polycrystalline Co35Fe65/NiMn bilayer. Semi-quantitative maps of the magnetic induction were obtained at different field values by the differential phase contrast (DPC) technique adapted for a TEM (SIDPC). The hysteresis loop of the bilayer has been calculated from the relative intensity of magnetic maps. The curve shows the appearance of an exchange-bias field reveals with two distinct reversal modes of the magnetization: the first path corresponds to a reversal by wall propagation when the applied field is parallel to the anisotropy direction whereas the second is a reversal by coherent rotation of magnetic moments when the field is applied antiparallel to unidirectional anisotropy direction

Do not forget the electrochemical characteristics of the membrane electrode assembly when designing a Proton Exchange Membrane Fuel Cell stack

International audienceThe membrane electrode assembly (MEA) is the key component of a PEMFC stack. Conventional MEAs are composed of catalyzed electrodes loaded with 0.1-0.4 mgPt cm−2 pressed against a Nafion® membrane, leading to cell performance close to 0.8 W cm−2 at 0.6 V. Due to their limited stability at high temperatures, the cost of platinum catalysts and that of proton exchange membranes, the recycling problems and material availability, the MEA components do not match the requirements for large scale development of PEMCFs at a low cost, particularly for automotive applications. Novel approaches to medium and high temperature membranes are described in this work, and a composite polybenzimidazole-poly(vinylphosphonic) acid membrane, stable up to 190 ◦C, led to a power density of 0.5 W cm−2 at 160 ◦C under 3 bar abs with hydrogen and air. Concerning the preparation of efficient electrocatalysts supported on a Vulcan XC72 carbon powder, the Bönnemann colloidal method and above all plasma sputtering allowed preparing bimetallic platinum-based electrocatalysts with a low Pt loading. In the case of plasma deposition of Pt nanoclusters, Pt loadings as low as 10 g cm−2 were achieved, leading to a very high mass power density of ca. 20 kW g−1 Pt . Finally characterization of the MEA electrical properties by Electrochemical Impedance Spectroscopy (EIS) based on a theoretical model of mass and charge transport inside the active and gas diffusion layers, together with the optimization of the operating parameters (cell temperature, humidity, flow rate and pressure) allowed obtaining electrical performance greater than 1.2 W cm−2 using an homemade MEA with a rather low Pt loading

Si and Si-rich silicon-nitride waveguides for optical transmissions and wavelength conversion around 2µm

We show that cm-long silicon or silicon-rich nitride waveguides with subwavelength transverse dimensions can efficiently sustain high-speed transmissions at 2 μm. We report the transmission of a 10 Gbit/s signal with negligible power penalty. Parametric conversion in both continuous and pulsed pump regimes is also demonstrated

Notch1 regulates hippocampal plasticity through interaction with the reelin pathway, glutamatergic transmission and CREB signaling

Notch signaling plays a crucial role in adult brain function such as synaptic plasticity, memory and olfaction. Several reports suggest an involvement of this pathway in neurodegenerative dementia. Yet, to date, the mechanism underlying Notch activity in mature neurons remains unresolved. In this work, we investigate how Notch regulates synaptic potentiation and contributes to the establishment of memory in mice. We observe that Notch1 is a postsynaptic receptor with functional interactions with the Reelin receptor, apolipoprotein E receptor 2 (ApoER2) and the ionotropic receptor, N-methyl-D-aspartate receptor (NMDAR). Targeted loss of Notch1 in the hippocampal CA fields affects Reelin signaling by influencing Dab1 expression and impairs the synaptic potentiation achieved through Reelin stimulation. Further analysis indicates that loss of Notch1 affects the expression and composition of the NMDAR but not AMPAR. Glutamatergic signaling is further compromised through downregulation of CamKII and its secondary and tertiary messengers resulting in reduced cAMP response element-binding (CREB) signaling. Our results identify Notch1 as an important regulator of mechanisms involved in synaptic plasticity and memory formation. These findings emphasize the possible involvement of this signaling receptor in dementia

Design of InGaAs/InP 1.55μm vertical cavity surface emitting lasers

International audienceThe design of an electrically pumped InGaAs quantum well based vertical cavity surface emitting laser (VCSEL) on InP substrate is presented. Such optically pumped VCSELs have already been demonstrated. To design electrically pumped VCSEL, three simulations steps are needed: optical simulation gives access to the electric field repartition, to design the active zone and the Bragg mirrors. Thermal simulation is helpful to design metallic contacts while the energy band diagram is obtained by electrical simulation to design the buried tunnel junction useful for carrier injection. All these simulations are compared to experiment

Characterization of InAs quantum wires on (001) InP: toward the realization of VCSEL structures with a stabilized polarization

International audienceVertical cavity surface emitting lasers (VCSELs) operating at 1.55-µm are of great interests in optical telecommunication applications. Their circular, spectral and spatial single mode laser beam is essential points for an efficient fiber coupling and high frequency modulation. Moreover, their low-cost production and the possibility to test each laser directly on the wafer represent great advantages for production applications. In contrast with edge emitting lasers, VCSEL present an important polarization instability, which may increase the bit error rate in data transmission. Different solutions have been proposed for controlling the polarization, from patterning the output mirror or by using a birefringent material on top of the mirror, which do complicate the device technology. In this contribution, we propose to use a gain material presenting an important polarization anisotropy like quantum wires in order to fix the polarization of the emitting VCSEL

InAs quantum wires on InP substrate for VCSEL applications

International audienceQuantum dash based vertical cavity surface emitting lasers (VCSEL) on InP substrate are presented. Single and close stacking layers were successfully grown with molecular beam epitaxy. Optimized quantum dash layers exhibit a strong polarized 1.55 µm photoluminescence along the [1-10] crystallographic axis. Continuous wave laser emission is demonstrated at room temperature for the first time on a quantum dash VCSEL structure on InP susbtrate. The quantum dash VCSEL laser polarization appears stable on the whole sample and with excitation, no switching is observed. Its polarization is mainly oriented along [1-10], an extinction coefficient of 30 dB is measured. Those preliminary results demonstrate the interests of quantum dashes in the realization of controlled and stable polarization VCSEL device

Un établissement rural mérovingien à Delle « La Queue au Loup » (Territoire de Belfort)

Découvert à l’occasion des diagnostics archéologiques conduits à l’ouest de la ville de Delle, dans le Territoire de Belfort, cet établissement mérovingien prend place sur un coteau de la Batte, à 300 m d’un grand domaine gallo-romain situé sur l’autre versant de la vallée. D’emblée cette occupation se caractérise par un grand édifice construit selon une architecture mixte associant la pierre et l’emploi de matériaux périssables, succédant à une première construction sur poteaux. D’une emprise de 230 m2 au sol, ce bâtiment présente des vestiges de sols, de cloisonnements et d’aménagements internes, assez rares pour la période, offrant matière à réflexion sur la fonction de ces différentes pièces, couplée à une analyse de dosage de phosphate contenu dans le sol. Le mobilier, assez modeste, et les datations radiocarbone permettent de situer l’occupation du milieu du vie à la première moitié du viie siècle. Des exemples de plus en plus nombreux de ces architectures de pierre sont révélés par l’archéologie préventive de ces toutes dernières années et constituent l’un des traits originaux de l’habitat du haut Moyen Âge de l’Arc jurassien.This merovingian establishment discovered during an archaeological evaluation to the west of the town of Delle in the Belfort territory is located on the Batte hillside about 300 m from the large Gallo-roman domain on the opposite slope of the valley. This settlement is characterised by a large edifice built of stone and perishable materials, which replaces a timber framed building. The building covers 230 m2 and vestiges of the floors, partitions and interior fittings are preserved which is rare for the period. The analysis of phosphate levels has given indications as to the function of each room. The finds are modest, but they do date, along with radiocarbon analysis, the settlement from the middle of the 6th century to the first half of the 7th century. More and more examples of this type of stone architecture have been revealed by preventive archaeology in the last few years which constitute one of the more original aspects of Early Medieval settlement in the Jura.Der bei archäologischen Diagnosen im Westen von Delle, im Departement Territoire de Belfort entdeckte merowingische Siedlungskomplex befindet sich 300 m entfernt von einem am gegenüberliegenden Hang des Tales der Batte liegenden großen gallo-römischen Gutshof. Zunächst charakterisiert sich der Komplex durch ein großes Gebäude, bei dessen Errichtung neben Stein vergängliche Baumaterialien verwandt wurden, und das auf einen Pfostenbau folgt. Das Gebäude mit einer Bodenfläche von 230 m2 weist Überreste von Fußböden, Zwischenwänden und Inneneinrichtung auf, die für diese Zeit relativ selten sind. Sie bieten Gelegenheit, sich über die Funktion der verschiedenen Räume Gedanken zu machen; die Untersuchung ist mit einer Analyse des im Boden enthaltenen Phosphats gekoppelt. Das relativ bescheidenen Mobiliar und die 14-C-Datierungen ergeben eine Nutzung von Mitte des 6. bis zur ersten Hälfte des 7. Jahrhunderts. Die Präventivarchäologie hat in den letzten Jahren immer mehr Beispiele dieser Steinbauten nachgewiesen, die eines der bezeichnenden Merkmale des frühmittelalterlichen Siedlungswesens im Jurabogen sind