118 research outputs found
Effets de la fampridine sur les paramètres de marche, la fonction des membres supérieurs, la fatigue et la qualité de vie chez les patients atteints de sclérose en plaques
Performance of DFT functionals for calculating the second-order nonlinear optical properties of dipolar merocyanines
MuSK is required for anchoring acetylcholinesterase at the neuromuscular junction
At the neuromuscular junction, acetylcholinesterase (AChE) is mainly present as asymmetric forms in which tetramers of catalytic subunits are associated to a specific collagen, collagen Q (ColQ). The accumulation of the enzyme in the synaptic basal lamina strictly relies on ColQ. This has been shown to be mediated by interaction between ColQ and perlecan, which itself binds dystroglycan. Here, using transfected mutants of ColQ in a ColQ-deficient muscle cell line or COS-7 cells, we report that ColQ clusterizes through a more complex mechanism. This process requires two heparin-binding sites contained in the collagen domain as well as the COOH terminus of ColQ. Cross-linking and immunoprecipitation experiments in Torpedo postsynaptic membranes together with transfection experiments with muscle-specific kinase (MuSK) constructs in MuSK-deficient myotubes or COS-7 cells provide the first evidence that ColQ binds MuSK. Together, our data suggest that a ternary complex containing ColQ, perlecan, and MuSK is required for AChE clustering and support the notion that MuSK dictates AChE synaptic localization at the neuromuscular junction
Disparités d’adoption des technologies en pédagogie universitaire : un aperçu empirique
Bien que les études traitant de l’intégration des technologies en pédagogie universitaire soient relativement nombreuses, peu d’entre elles se sont penchées sur les disparités d’adoption des technologies parmi les enseignants universitaires. Aussi, l’objectif de cet article est de caractériser les profils d’enseignants universitaires adoptant les technologies. Un questionnaire a été rempli par 391 enseignants de deux universités du Québec. Des analyses par clusters permettent d’identifier trois profils d’enseignants universitaires intégrant les technologies relativement à trois volets de leur enseignement : préparation et gestion, pilotage, et développement professionnel. Les résultats laissent penser que les disparités d’adoption ne se sont pas résorbées malgré la succession de plus en plus rapide des technologies en pédagogie universitaire
First Detection of Polarization of the Submillimetre Diffuse Galactic Dust Emission by Archeops
We present the first determination of the Galactic polarized emission at 353
GHz by Archeops. The data were taken during the Arctic night of February 7,
2002 after the balloon--borne instrument was launched by CNES from the Swedish
Esrange base near Kiruna. In addition to the 143 GHz and 217 GHz frequency
bands dedicated to CMB studies, Archeops had one 545 GHz and six 353 GHz
bolometers mounted in three polarization sensitive pairs that were used for
Galactic foreground studies. We present maps of the I, Q, U Stokes parameters
over 17% of the sky and with a 13 arcmin resolution at 353 GHz (850 microns).
They show a significant Galactic large scale polarized emission coherent on the
longitude ranges [100, 120] and [180, 200] deg. with a degree of polarization
at the level of 4-5%, in agreement with expectations from starlight
polarization measurements. Some regions in the Galactic plane (Gem OB1,
Cassiopeia) show an even stronger degree of polarization in the range 10-20%.
Those findings provide strong evidence for a powerful grain alignment mechanism
throughout the interstellar medium and a coherent magnetic field coplanar to
the Galactic plane. This magnetic field pervades even some dense clouds.
Extrapolated to high Galactic latitude, these results indicate that
interstellar dust polarized emission is the major foreground for PLANCK-HFI CMB
polarization measurement.Comment: Submitted to Astron. & Astrophys., 14 pages, 12 Fig., 2 Table
A jump-growth model for predator-prey dynamics: derivation and application to marine ecosystems
This paper investigates the dynamics of biomass in a marine ecosystem. A
stochastic process is defined in which organisms undergo jumps in body size as
they catch and eat smaller organisms. Using a systematic expansion of the
master equation, we derive a deterministic equation for the macroscopic
dynamics, which we call the deterministic jump-growth equation, and a linear
Fokker-Planck equation for the stochastic fluctuations. The McKendrick--von
Foerster equation, used in previous studies, is shown to be a first-order
approximation, appropriate in equilibrium systems where predators are much
larger than their prey. The model has a power-law steady state consistent with
the approximate constancy of mass density in logarithmic intervals of body mass
often observed in marine ecosystems. The behaviours of the stochastic process,
the deterministic jump-growth equation and the McKendrick--von Foerster
equation are compared using numerical methods. The numerical analysis shows two
classes of attractors: steady states and travelling waves.Comment: 27 pages, 4 figures. Final version as published. Only minor change
Temperature and polarization angular power spectra of Galactic dust radiation at 353 GHz as measured by Archeops
We present the first measurement of temperature and polarization angular
power spectra of the diffuse emission of Galactic dust at 353 GHz as seen by
Archeops on 20% of the sky. The temperature angular power spectrum is
compatible with that provided by the extrapolation to 353 GHz of IRAS and DIRBE
maps using \cite{fds} model number 8. For Galactic latitudes deg
we report a 4 sigma detection of large scale ()
temperature-polarization cross-correlation and set upper limits to the and modes at . For Galactic latitudes deg, on the same
angular scales, we report a 2 sigma detection of temperature-polarization
cross-correlation . These
results are then extrapolated to 100 GHz to estimate the contamination in CMB
measurements by polarized diffuse Galactic dust emission. The signal is
then and for and 10 deg.
respectively. The upper limit on and becomes . If polarized dust emission at higher Galactic latitude cuts is
similar to the one we report here, then dust polarized radiation will be a
major foreground for determining the polarization power spectra of the CMB at
high frequencies above 100 GHz.Comment: 11 pages, 8 figures, submitted to A
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