648 research outputs found
Characterization and limits of a cold atom Sagnac interferometer
We present the full evaluation of a cold atom gyroscope based on atom
interferometry. We have performed extensive studies to determine the systematic
errors, scale factor and sensitivity. We demonstrate that the acceleration
noise can be efficiently removed from the rotation signal allowing to reach the
fundamental limit of the quantum projection noise for short term measurements.
The technical limits to the long term sensitivity and accuracy have been
identified, clearing the way for the next generations of ultra-sensitive atom
gyroscopes
Potentialités androgénétiques du palmier dattier Phoenix dactylifera L. et culture in vitro d'anthÚres
Genetic potentialities if five male date palm genotypes, and in vitro culture of anthers. The experimental results derived from the study of five date palm (Phoenix dactylifera L.) genotypes indicate that the ability of microspores to divide varies with genotype and culture medium. The highest frequency of microspore division is obtained with the induction medium [Murashige and Skoog (MS 1962) mineral elements, 2,4-dichlorophenoxyacetique (2,4-D), 2-isopentenylaminopurine (2-IP)] containing activated charcoal. The pollinator T106 was considered as the most efficient genotype in our experimentatio
EHMTI-0266. Validation of a sham manipulative procedure: a new protocol for conducting placebo-control clinical trials in manual therapy
Background: Few manual therapy studies have attempted to conduct placebo-control clinical trials. Thus, quantification of alleged placebo effects consequently becomes difficult. Aim: To investigate and validate a new placebo intervention for spinal manipulative therapy clinical trials, i.e. sham manipulation, and investigate the feasibility of a short de-blinding questionnaire. Method: A single blinded, prospective randomized, placebo-controlled trial with 1 month baseline and 3 months treatment with 12 treatments. 104 participants diagnosed with migraine were equally randomized into 1 of 3 groups: (i) chiropractic spinal manipulative therapy (CSMT), (ii) placebo (sham manipulation), (iii) control group (continued usual management). The participants filled in questionnaire on de-blinding after each treatment session. Primary end-point was the rate of successful blinding through de-blinding questionnaires given after each treatment session. Results: 772 out of 840 individual cases were analyzed, only 8.1 % out of all cases missed their appointment. The unadjusted result shows that both the active and placebo group believed they received active treatment with odds ratio (OR) of â„88.9 and â„80.0 respectively. Due to strong cluster effect in our data, logistic regression model was used to adjust for repeated measures which showed a significant OR of >10 in both the active and the placebo group. Conclusion: This is the first study to successfully demonstrate a manipulative sham procedure over a full length treatment period, assessing the placebo group with de-blinding questionnaire after each session which thus, could be incorporated in future clinical trials.1 page(s
Ătude de lâĂ©volution du littoral de la baie dâEl Jadida (Maroc) par photo-interprĂ©tation
La baie dâEl Jadida se situe sur la façade atlantique du Maroc (entre 33° 15â 00ââ et 33° 21â 40ââ de latitude Nord, 8° 18â 00ââ et 8° 30â 00ââ de longitude Ouest). Elle constitue un grand systĂšme sableux fortement marquĂ© par la dynamique littorale. Lâutilisation des photographies aĂ©riennes permet de dĂ©terminer dâune part, lâĂ©volution du trait de cĂŽte Ă lâembouchure de lâOum Rbia Ă long terme (de 1949 Ă 1996) et dâautre part.de mesurer lâĂ©volution de lâensemble du littoral de la baie El Jadida Ă moyen terme (de 1988 Ă 1997). Les rĂ©sultats de lâĂ©tude diachronique confirment la variabilitĂ© spatio-temporelle et lâĂ©volution du littoral de la baie dâEl Jadida avec des zones en Ă©rosion et dâautres en accumulation. Lâanalyse des variations des traits de cĂŽte, Ă moyen terme, ne montre pas des modifications importantes. Les seuls changements ont Ă©tĂ©Â enregistrĂ©s au niveau des unitĂ©s morphologiques composant ce littoral (plage aĂ©rienne, dunes,âŠ). LâĂ©volution du trait de cĂŽte Ă long terme se caractĂ©rise par une forte variabilitĂ© dans le secteur de lâestuaire de lâOum Rbia. La pĂ©riode dâĂ©rosion la plus importante se situe entre 1949 et 1996 avec un taux de recul de 45 m (1,28 m/an). Durant cette mĂȘme pĂ©riode, on distingue aussi une variabilitĂ© spatiale qui se traduit par lâexistence de deux secteurs trĂšs diffĂ©rents : le premier est caractĂ©risĂ© par une forte Ă©rosion (plage de la rive droite) et le deuxiĂšme est favorisĂ© par des accumulations importantes (flĂšche sableuse de la rive gauche).Mots-clĂ©s : baie dâEl Jadida, plage, estuaire, trait de cĂŽte, Ă©volution morphologique, Ă©volution diachronique, flĂšche sableuse, Maroc. Study of coastline evolution of the El Jadida bay (Morocco) by photo-interpretationEl Jadida bay, is located on the middle of the Atlantic coast of Morocco (between 33° 15â 00ââ and 33° 21â 40ââ North and between 8° 18â 00ââ and 8° 30â 00ââ West), constitute a large sandy stock strongly marked by the littoral dynamic. The use of the aerial photographs permit to identify the coast evolution to the Oum Rbia estuary (of 1949 to 1996) and to measure the littoral of the bay El Jadida evolution in medium-term. The results of this diachronic study confirm space and time variability in the littoral of bay evolution with deepening reachâs and others of sedimentation. The coastline variation analysis in medium-term doesnât give satisfactory results. The only changes were registered at the morphological units of the coast (aerial beach, dunes, ... ). The coastline evolution in the long-term coast is characterized by a strong variability in the Oum Rbia estuary. The period of the most important erosion ranges between 1949 and 1996 with a rate of retreat of 45 m (1.28 m/an). During this period, we can also notice a space variability which results in the existence of two very different sectors: the first is characterized by strong erosion (beach of Right Bank) and the second is characterized by accumulations (sandy arrow of left bank).Keywords : El Jadida bay, estuary, coastline, morphologic evolution, diachronic evolution, sandy arrow, Morocco
Matter-wave laser Interferometric Gravitation Antenna (MIGA): New perspectives for fundamental physics and geosciences
The MIGA project aims at demonstrating precision measurements of gravity with
cold atom sensors in a large scale instrument and at studying the associated
applications in geosciences and fundamental physics. The first stage of the
project (2013-2018) will consist in building a 300-meter long optical cavity to
interrogate atom interferometers and will be based at the low noise underground
laboratory LSBB in Rustrel, France. The second stage of the project (2018-2023)
will be dedicated to science runs and data analyses in order to probe the
spatio-temporal structure of the local gravity field of the LSBB region, a site
of high hydrological interest. MIGA will also assess future potential
applications of atom interferometry to gravitational wave detection in the
frequency band Hz hardly covered by future long baseline optical
interferometers. This paper presents the main objectives of the project, the
status of the construction of the instrument and the motivation for the
applications of MIGA in geosciences. Important results on new atom
interferometry techniques developed at SYRTE in the context of MIGA and paving
the way to precision gravity measurements are also reported.Comment: Proceedings of the 50th Rencontres de Moriond "100 years after GR",
La Thuile (Italy), 21-28 March 2015 - 10 pages, 5 figures, 23 references
version2: added references, corrected typo
I.C.E.: An Ultra-Cold Atom Source for Long-Baseline Interferometric Inertial Sensors in Reduced Gravity
The accuracy and precision of current atom-interferometric inertialsensors
rival state-of-the-art conventional devices using artifact-based test masses .
Atomic sensors are well suited for fundamental measurements of gravito-inertial
fields. The sensitivity required to test gravitational theories can be achieved
by extending the baseline of the interferometer. The I.C.E.
(Interf\'erom\'etrie Coh\'erente pour l'Espace) interferometer aims to achieve
long interrogation times in compact apparatus via reduced gravity. We have
tested a cold-atom source during airplane parabolic flights. We show that this
environment is compatible with free-fall interferometric measurements using up
to 4 second interrogation time. We present the next-generation apparatus using
degenerate gases for low release-velocity atomic sources in space-borne
experiments
Low noise amplication of an optically carried microwave signal: application to atom interferometry
In this paper, we report a new scheme to amplify a microwave signal carried
on a laser light at =852nm. The amplification is done via a
semiconductor tapered amplifier and this scheme is used to drive stimulated
Raman transitions in an atom interferometer. Sideband generation in the
amplifier, due to self-phase and amplitude modulation, is investigated and
characterized. We also demonstrate that the amplifier does not induce any
significant phase-noise on the beating signal. Finally, the degradation of the
performances of the interferometer due to the amplification process is shown to
be negligible
Calibration and sensitivity of the Virgo detector during its second science run
The Virgo detector is a kilometer-length interferometer for gravitational
wave detection located near Pisa (Italy). During its second science run (VSR2)
in 2009, six months of data were accumulated with a sensitivity close to its
design. In this paper, the methods used to determine the parameters for
sensitivity estimation and gravitational wave reconstruction are described. The
main quantities to be calibrated are the frequency response of the mirror
actuation and the sensing of the output power. Focus is also put on their
absolute timing. The monitoring of the calibration data as well as the
parameter estimation with independent techniques are discussed to provide an
estimation of the calibration uncertainties. Finally, the estimation of the
Virgo sensitivity in the frequency-domain is described and typical
sensitivities measured during VSR2 are shown.Comment: 30 pages, 23 figures, 1 table. Published in Classical and Quantum
Gravity (CQG), Corrigendum include
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