Proof-of-principle demonstration of vertical gravity gradient measurement using a single proof mass double-loop atom interferometer

We demonstrate a proof-of-principle of direct Earth gravity gradient measurement with an atom interferometer-based gravity gradiomter using a single proof mass of cold 87 rubidium atoms. The atomic gradiometer is implemented in the so-called double-loop configuration, hence providing a direct gravity gradient dependent phase shift insensitive do DC acceleration and constant rotation rate. The atom interferometer (AI) can be either operated as a gravimeter or a gradiomter by simply adding an extra Raman $\pi$-pulse. We demonstrate gravity gradient measurements first using a vibration isolation platform and second without seismic isolation using the correlation between the AI signal and the vibration signal measured by an auxilliary classical accelerometer. The simplicity of the experimental setup (a single atomic source and unique detection) and the immunity of the AI to rotation-induced contrast loss, make it a good candidate for onboard gravity gradient measurements.Comment: 11 pages, 7 figure

Zero-velocity atom interferometry using a retroreflected frequency chirped laser

International audienceAtom interferometry using stimulated Raman transitions in a retroreflected configuration is the first choice in high-precision measurements because it provides low phase noise, a high-quality Raman wave front, and a simple experimental setup. However, it cannot be used for atoms at zero velocity because two pairs of Raman lasers are simultaneously resonant. Here we report a method which allows this degeneracy to be lifted by using a frequency chirp on the Raman lasers. Using this technique, we realize a Mach-Zehnder atom interferometer hybridized with a force balanced accelerometer which provides horizontal acceleration measurements with a short-term sensitivity of 3.2×10−5ms−2/Hz. This technique could be used for multiaxis inertial sensors, tiltmeters, or atom interferometry in a microgravity environment

Vers une méthode de conception HYGRO-thermique des BATiments performants : démarche du projet HYGRO-BAT

Cet article présente la démarche mise en oeuvre dans le projet collaboratif ANR Hygrobat, qui vise à donner des outils pour quantifier de manière fiable l'impact des transferts de masse sur les transferts de chaleur dans les parois de bâtiments comprenant des matériaux fortement hygroscopiques. Les matériaux sélectionnés dans ce projets (fibre de bois, bois massif, OSB) ont été soigneusement caractérisés. Leurs propriétés hygrothermiques ont été mesurées en laboratoire, puis ils ont été mis en oeuvre dans des parois, soumises à des conditions aux limites de variées. L'originalité de l'étude réside dans : (i) la démarche "pas à pas" de complexité croissante, partant des caractérisations d'un seul matériau en conditions stationnaires, jusqu'aux mesures sur une paroi multicouche en climat réel ; (ii) les vérifications croisées de mesures expérimentales, qui sont effectuées dans deux des laboratoires partenaires du projet, parfois sur des dispositifs différents ; (iii) association des benchmarks expérimentaux et numérique

Dynamique de la réponse optique non-linéaire ultra-rapide d'una assemblée de nanoparticules d'or

PARIS-BIUSJ-Thèses (751052125) / SudocPARIS-BIUSJ-Physique recherche (751052113) / SudocSudocFranceF

Intérêt et évolution des différents examens complémentaires radiologiques en implantologie

NANCY1-SCD Pharmacie-Odontologie (543952101) / SudocPARIS-BIUM (751062103) / SudocNANCY1-Bib. numérique (543959902) / SudocSudocFranceF

Axonal involvement in the Wlds neuroprotective effect: analysis of pure motoneurons in a mouse model protected from motor neuron disease at a pre-symptomatic age

International audienceThe identification of the Wlds gene that delays axonal degeneration in several models of neurodegenerative disease provides an interesting tool to study mechanisms of axonal loss. We showed that crossing a mouse mutant with a motoneuron disease (pmn for progressive motor neuronopathy) with mice that express the Wlds gene delayed axonal loss, increased the life span, partially rescued axonal transport deficit and prolonged the survival of the motoneuron cell bodies. To determine factors involved in the neuroprotective effect of Wlds, we combined laser capture microdissection and microarray analysis to identify genes that are differentially regulated at a pre-symptomatic age in motoneuron cell bodies in pmn/pmn,Wlds/Wlds mice as compared with pmn/pmn mice. Only 56 genes were de-regulated; none of the 'classical' genes implicated in apoptosis were de-regulated. Interestingly, a large proportion of these genes are related to axonal function and to retrograde and anterograde transport (i.e. members of the dynactin complex and kinesin family). These results were confirmed by real-time PCR, in situ hybridization and at protein level in sciatic nerves. Thus, genes related to axonal function and in particular to axonal transport may be involved at an early stage in the neuroprotective property of the Wlds gene and confirm the importance of axonal involvement in this model of motor neuron disease

Gacyclidine improves the survival and reduces motor deficits in a mouse model of amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disorder typified by a massive loss of motor neurons with few therapeutic options. The exact cause of neuronal degeneration is unknown but it is now admitted that ALS is a multifactorial disease with several mechanisms involved including glutamate excitotoxicity. More specifically, N-methyl-D-aspartate (NMDA)-mediated cell death and impairment of the glutamate-transport has been suggested to play a key role in ALS pathophysiology. Thus, evaluating NMDAR antagonists is of high therapeutic interest. Gacyclidine, also named GK11, is a high affinity non-competitive NMDAR antagonist that may protect against motor neuron death in an ALS context. Moreover, GK11 presents a low intrinsic neurotoxicity and has already been used in two clinical trials for CNS lesions. <br/>In the present study, we investigated the influence of chronic administration of two doses of GK11 (0.1 and 1 mg/kg) on the survival and the functional motor activity of hSOD1G93A mice, an animal model of ALS. Treatment started at early symptomatic age (60 days) and was applied bi-weekly until the end stage of the disease. We first confirmed that functional alteration of locomotor activity was evident in the hSOD1G93A transgenic female mice by 60 days of age. A low dose of GK11 improved the survival of the mice by 4.3% and partially preserved body weight. Improved life span was associated with a delay in locomotor function impairment. Conversely, the high dose treatment worsened motor functions. <br/>These findings suggest that chronic administration of GK11beginning at early symptomatic stage may be beneficial for patients with ALS