1,429 research outputs found
Apport de la mesure de la pression artérielle centrale ambulatoire dans la caractérisation phénotypique de la démence de type Alzheimer
Dans les pays développés, la prévalence des démences est de 5% chez les plus de 65ans et doublerait pour chaque tranche d'âge de 10 ans. Avec le vieillissement de la population, le nombre de personnes atteintes de démence augmente chaque année, ce qui pose le problème de trouver rapidement des thérapies et mesures de prévention efficaces.
Il est connu que l'hypertension artérielle (HTA) est un facteur de risque pour certaines démences. De plus, de récentes études démontrent que la pression artérielle centrale serait un marqueur hémodynamique plus représentatif des lésions causées au cerveau, dues à une HTA, que la pression périphérique usuellement mesurée.
Il serait donc intéressant d'évaluer si la démence est associée à une augmentation de la pression artérielle centrale, en comparaison avec des patients hypertendus non déments.
But de l'étude : Cette étude a pour but de quantifier l'apport de la mesure de la pression artérielle centrale ambulatoire dans la caractérisation des patients
avec une démence de type Alzheimer.
L'objectif principal est de déterminer la taille de la différence de pression artérielle centrale et son écart-‐type entre les patients hypertendus avec ou sans démence de type Alzheimer afin de pouvoir calculer le nombre de patients nécessaire pour montrer une différence significative.
Dans cette étude, nous allons tester l'hypothèse que la pression artérielle centrale (moyenne, systolique et diastolique) est plus élevée chez les patients atteints de troubles cognitifs et/ou qu'ils présentent des perturbations du rythme circadien plus marquées, notamment pour les valeurs durant le sommeil, (non-‐dipping, reverse dipping, extreme dipping)
Broadening of hot-spot response spectrum of superconducting NbN nanowire single-photon detector with reduced nitrogen content
The spectral detection efficiency and the dark count rate of superconducting
nanowire single-photon detectors (SNSPD) has been studied systematically on
detectors made from thin NbN films with different chemical compositions.
Reduction of the nitrogen content in the 4 nm thick NbN films results in a more
than two orders of magnitude decrease of the dark count rates and in a red
shift of the cut-off wavelength of the hot-spot SNSPD response. The observed
phenomena are explained by an improvement of uniformity of NbN films that has
been confirmed by a decrease of resistivity and an increase of the ratio of the
measured critical current to the depairing current. The latter factor is
considered as the most crucial for both the cut-off wavelength and the dark
count rates of SNSPD. Based on our results we propose a set of criteria for
material properties to optimize SNSPD in the infrared spectral region.Comment: 15 pages, 6 figure
Invariant four-forms and symmetric pairs
We give criteria for real, complex and quaternionic representations to define
s-representations, focusing on exceptional Lie algebras defined by spin
representations. As applications, we obtain the classification of complex
representations whose second exterior power is irreducible or has an
irreducible summand of co-dimension one, and we give a conceptual
computation-free argument for the construction of the exceptional Lie algebras
of compact type.Comment: 16 pages [v2: references added, last section expanded
Characterization of thermal effects in the Enhanced LIGO Input Optics
We present the design and performance of the LIGO Input Optics subsystem as
implemented for the sixth science run of the LIGO interferometers. The Initial
LIGO Input Optics experienced thermal side effects when operating with 7 W
input power. We designed, built, and implemented improved versions of the Input
Optics for Enhanced LIGO, an incremental upgrade to the Initial LIGO
interferometers, designed to run with 30 W input power. At four times the power
of Initial LIGO, the Enhanced LIGO Input Optics demonstrated improved
performance including better optical isolation, less thermal drift, minimal
thermal lensing and higher optical efficiency. The success of the Input Optics
design fosters confidence for its ability to perform well in Advanced LIGO
Small optic suspensions for Advanced LIGO input optics and other precision optical experiments
We report on the design and performance of small optic suspensions developed
to suppress seismic motion of out-of-cavity optics in the Input Optics
subsystem of the Advanced LIGO interferometric gravitational wave detector.
These compact single stage suspensions provide isolation in all six degrees of
freedom of the optic, local sensing and actuation in three of them, and passive
damping for the other three
Hamiltonian reductions of free particles under polar actions of compact Lie groups
Classical and quantum Hamiltonian reductions of free geodesic systems of
complete Riemannian manifolds are investigated. The reduced systems are
described under the assumption that the underlying compact symmetry group acts
in a polar manner in the sense that there exist regularly embedded, closed,
connected submanifolds meeting all orbits orthogonally in the configuration
space. Hyperpolar actions on Lie groups and on symmetric spaces lead to
families of integrable systems of spin Calogero-Sutherland type.Comment: 15 pages, minor correction and updated references in v
Polar foliations and isoparametric maps
A singular Riemannian foliation on a complete Riemannian manifold is
called a polar foliation if, for each regular point , there is an immersed
submanifold , called section, that passes through and that meets
all the leaves and always perpendicularly. A typical example of a polar
foliation is the partition of into the orbits of a polar action, i.e., an
isometric action with sections. In this work we prove that the leaves of
coincide with the level sets of a smooth map if is simply
connected. In particular, we have that the orbits of a polar action on a simply
connected space are level sets of an isoparametric map. This result extends
previous results due to the author and Gorodski, Heintze, Liu and Olmos, Carter
and West, and Terng.Comment: 9 pages; The final publication is available at springerlink.com
http://www.springerlink.com/content/c72g4q5350g513n1
Overview of Advanced LIGO Adaptive Optics
This is an overview of the adaptive optics used in Advanced LIGO (aLIGO),
known as the thermal compensation system (TCS). The thermal compensation system
was designed to minimize thermally-induced spatial distortions in the
interferometer optical modes and to provide some correction for static
curvature errors in the core optics of aLIGO. The TCS is comprised of ring
heater actuators, spatially tunable CO laser projectors and Hartmann
wavefront sensors. The system meets the requirements of correcting for nominal
distortion in Advanced LIGO to a maximum residual error of 5.4nm, weighted
across the laser beam, for up to 125W of laser input power into the
interferometer
Experimental Study of the Radiative Decays K+ -> mu+ nu e+e- and K+ -> e+ nu e+e-
Experiment 865 at the Brookhaven AGS obtained 410 K+ -> e+ nu e+e- and 2679
K+ -> mu+ nu e+e- events including 10% and 19% background. The branching ratios
were measured to be (2.48+-0.14(stat.)+-0.14(syst.))x10^-8 (m_ee>150 MeV) and
(7.06+-0.16+-0.26)x10^-8 (m_ee>145 MeV), respectively. Results for the decay
form factors are presented.Comment: 4 pages, 3 figures, RevTeX
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