1,047 research outputs found

    Characterization and limits of a cold atom Sagnac interferometer

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    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'anthères

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    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

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    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 ≥88.9 and ≥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

    I.C.E.: An Ultra-Cold Atom Source for Long-Baseline Interferometric Inertial Sensors in Reduced Gravity

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    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

    Matter-wave laser Interferometric Gravitation Antenna (MIGA): New perspectives for fundamental physics and geosciences

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    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 0.110\sim 0.1-10 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

    Low noise amplication of an optically carried microwave signal: application to atom interferometry

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    In this paper, we report a new scheme to amplify a microwave signal carried on a laser light at λ\lambda=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

    Search for gravitational waves associated with the InterPlanetary Network short gamma ray bursts

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    We outline the scientific motivation behind a search for gravitational waves associated with short gamma ray bursts detected by the InterPlanetary Network (IPN) during LIGO's fifth science run and Virgo's first science run. The IPN localisation of short gamma ray bursts is limited to extended error boxes of different shapes and sizes and a search on these error boxes poses a series of challenges for data analysis. We will discuss these challenges and outline the methods to optimise the search over these error boxes.Comment: Methods paper; Proceedings for Eduardo Amaldi 9 Conference on Gravitational Waves, July 2011, Cardiff, U

    Implementation and testing of the first prompt search for gravitational wave transients with electromagnetic counterparts

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    Aims. A transient astrophysical event observed in both gravitational wave (GW) and electromagnetic (EM) channels would yield rich scientific rewards. A first program initiating EM follow-ups to possible transient GW events has been developed and exercised by the LIGO and Virgo community in association with several partners. In this paper, we describe and evaluate the methods used to promptly identify and localize GW event candidates and to request images of targeted sky locations. Methods. During two observing periods (Dec 17 2009 to Jan 8 2010 and Sep 2 to Oct 20 2010), a low-latency analysis pipeline was used to identify GW event candidates and to reconstruct maps of possible sky locations. A catalog of nearby galaxies and Milky Way globular clusters was used to select the most promising sky positions to be imaged, and this directional information was delivered to EM observatories with time lags of about thirty minutes. A Monte Carlo simulation has been used to evaluate the low-latency GW pipeline's ability to reconstruct source positions correctly. Results. For signals near the detection threshold, our low-latency algorithms often localized simulated GW burst signals to tens of square degrees, while neutron star/neutron star inspirals and neutron star/black hole inspirals were localized to a few hundred square degrees. Localization precision improves for moderately stronger signals. The correct sky location of signals well above threshold and originating from nearby galaxies may be observed with ~50% or better probability with a few pointings of wide-field telescopes.Comment: 17 pages. This version (v2) includes two tables and 1 section not included in v1. Accepted for publication in Astronomy & Astrophysic

    Multiparametric determination of genes and their point mutations for identification of beta-lactamases

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    More than half of all currently used antibiotics belong to the beta-lactam group, but their clinical effectiveness is severely limited by antibiotic resistance of microorganisms that are the causative agents of infectious diseases. Several mechanisms for the resistance of Enterobacteriaceae have been established, but the main one is the enzymatic hydrolysis of the antibiotic by specific enzymes called beta-lactamases. Beta-lactamases represent a large group of genetically and functionally different enzymes of which extended-spectrum beta-lactamases (ESBLs) pose the greatest threat. Due to the plasmid localization of the encoded genes, the distribution of these enzymes among the pathogens increases every year. Among ESBLs the most widespread and clinically relevant are class A ESBLs of TEM, SHV, and CTX-M types. TEM and SHV type ESBLs are derived from penicillinases TEM-1, TEM-2, and SHV-1 and are characterized by several single amino acid substitutions. The extended spectrum of substrate specificity for CTX-M beta-lactamases is also associated with the emergence of single mutations in the coding genes. The present review describes various molecular-biological methods used to identify determinants of antibiotic resistance. Particular attention is given to the method of hybridization analysis on microarrays, which allows simultaneous multiparametric determination of many genes and point mutations in them. A separate chapter deals with the use of hybridization analysis on microarrays for genotyping of the major clinically significant ESBLs. Specificity of mutation detection by means of hybridization analysis with different detection techniques is compared

    Étude de l’évolution du littoral de la baie d’El Jadida (Maroc) par photo-interprétation

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    La baie d’El Jadida se situe sur la façade atlantique du Maroc (entre 33° 15’ 00’’ et 33° 21’ 40’’ de latitude Nord, 8° 18’ 00’’ et 8° 30’ 00’’ de longitude Ouest). Elle constitue un grand système sableux fortement marqué par la dynamique littorale. L’utilisation des photographies aériennes permet de déterminer d’une part, l’évolution du trait de côte à l’embouchure de l’Oum Rbia à long terme (de 1949 à 1996) et d’autre part.de mesurer l’évolution de l’ensemble du littoral de la baie El Jadida à moyen terme (de 1988 à 1997). Les résultats de l’étude diachronique confirment la variabilité spatio-temporelle et l’évolution du littoral de la baie d’El Jadida avec des zones en érosion et d’autres en accumulation. L’analyse des variations des traits de côte, à moyen terme, ne montre pas des modifications importantes. Les seuls changements ont été enregistrés au niveau des unités morphologiques composant ce littoral (plage aérienne, dunes,…). L’évolution du trait de côte à long terme se caractérise par une forte variabilité dans le secteur de l’estuaire de l’Oum Rbia. La période d’érosion la plus importante se situe entre 1949 et 1996 avec un taux de recul de 45 m (1,28 m/an). Durant cette même période, on distingue aussi une variabilité spatiale qui se traduit par l’existence de deux secteurs très différents : le premier est caractérisé par une forte érosion (plage de la rive droite) et le deuxième est favorisé par des accumulations importantes (flèche sableuse de la rive gauche).Mots-clés : baie d’El Jadida, plage, estuaire, trait de côte, évolution morphologique, évolution diachronique, flèche 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° 15’ 00’’ and 33° 21’ 40’’ North and between 8° 18’ 00’’ and 8° 30’ 00’’ 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 reach’s and others of sedimentation. The coastline variation analysis in medium-term doesn’t 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
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