Towards a monolithic optical cavity for atom detection and manipulation

We study a Fabry-Perot cavity formed from a ridge waveguide on a AlGaAs substrate. We experimentally determined the propagation losses in the waveguide at 780 nm, the wavelength of Rb atoms. We have also made a numerical and analytical estimate of the losses induced by the presence of the gap which would allow the interaction of cold atoms with the cavity field. We found that the intrinsic finesse of the gapped cavity can be on the order of F ~ 30, which, when one takes into account the losses due to mirror transmission, corresponds to a cooperativity parameter for our system C ~ 1

A 2015 International Geomagnetic Reference Field (IGRF) candidate model based on <i>Swarm’s</i> experimental absolute magnetometer vector mode data

International audienceEach of the three satellites of the European Space Agency Swarm mission carries an absolute scalar magnetometer (ASM) that provides the nominal 1-Hz scalar data of the mission for both science and calibration purposes. These ASM instruments, however, also deliver autonomous 1-Hz experimental vector data. Here, we report on how ASM-only scalar and vector data from the Alpha and Bravo satellites between November 29, 2013 (a week after launch) and September 25, 2014 (for on-time delivery of the model on October 1, 2014) could be used to build a very valuable candidate model for the 2015.0 International Geomagnetic Reference Field (IGRF). A parent model was first computed, describing the geomagnetic field of internal origin up to degree and order 40 in a spherical harmonic representation and including a constant secular variation up to degree and order 8. This model was next simply forwarded to epoch 2015.0 and truncated at degree and order 13. The resulting ASM-only 2015.0 IGRF candidate model is compared to analogous models derived from the mission's nominal data and to the now-published final 2015.0 IGRF model. Differences among models mainly highlight uncertainties enhanced by the limited geographical distribution of the selected data set (essentially due to a lack of availability of data at high northern latitude satisfying nighttime conditions at the end of the time period considered). These appear to be comparable to differences classically observed among IGRF candidate models. These positive results led the ASM-only 2015.0 IGRF candidate model to contribute to the construction of the final 2015.0 IGRF model

International Geomagnetic Reference Field: the 12th generation

The 12th generation of the International Geomagnetic Reference Field (IGRF) was adopted in December 2014 by the Working Group V-MOD appointed by the International Association of Geomagnetism and Aeronomy (IAGA). It updates the previous IGRF generation with a definitive main field model for epoch 2010.0, a main field model for epoch 2015.0, and a linear annual predictive secular variation model for 2015.0-2020.0. Here, we present the equations defining the IGRF model, provide the spherical harmonic coefficients, and provide maps of the magnetic declination, inclination, and total intensity for epoch 2015.0 and their predicted rates of change for 2015.0-2020.0. We also update the magnetic pole positions and discuss briefly the latest changes and possible future trends of the Earth’s magnetic fiel

La faïence et la porcelaine à Pontenx

Petitcol Xavier, Lalanne François. La faïence et la porcelaine à Pontenx. In: Sèvres. Revue de la Société des Amis du musée national de Céramique, n°20, 2011. pp. 68-81

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Revêtement de surface nanostructurée pour générer des nouvelles apparences visuelles

Also published as FR3119385Nanostructured surface coating configured to generate visual appearances in a visible spectrum range, comprising: - a first layer comprising a random distribution of nanoparticles; a substrate, on which the first layer is arranged; the nanoparticles having an optical refraction index npart having a value suitable for each individually diffusing the incident light; the nanoparticles being arranged so that the mean distance between two adjacent particles d is defined in accordance with the following relationship so as to produce interference between the light diffused by the particles: 2 R ≤ d ≤ max (λ / np), where R is the smallest geometric radius of a circle surrounding the particle, λ is the greatest wavelength of the visible spectrum, and np is the optical refractive index of the medium in which the nanoparticles are dispersed.Revêtement de surface nanostructurée configuré pour générer des apparences visuelles dans une bande spectrale visible comprenant :- une première couche comprenant une distribution aléatoire de nanoparticules ; un substrat sur lequel est agencée la première couche ; les nanoparticules ayant un indice optique de réfraction npart présentant une valeur adaptée pour diffuser chacune individuellement la lumière incidente ; les nanoparticules étant agencées de sorte que la distance moyenne entre deux particules voisines d est définie selon la relation suivante de manière à produire une interférence entre la lumière diffusée par les particules : 2 R ≤ d ≤ max (λ / np) avec R le rayon géométrique le plus petit d’un cercle englobant la particule, λ la longueur d’onde la plus grande du spectre visible et np l’indice de réfraction optique du milieu dans lequel sont dispersées les nanoparticules

Nanostructured surface coating to generate new visual appearances

Revêtement de surface nanostructurée configuré pour générer des apparences visuelles dans une bande spectrale visible comprenant :- une première couche comprenant une distribution aléatoire de nanoparticules ; un substrat sur lequel est agencée la première couche ; les nanoparticules ayant un indice optique de réfraction npart présentant une valeur adaptée pour diffuser chacune individuellement la lumière incidente ; les nanoparticules étant agencées de sorte que la distance moyenne entre deux particules voisines d est définie selon la relation suivante de manière à produire une interférence entre la lumière diffusée par les particules : 2 R ≤ d ≤ max (λ / np) avec R le rayon géométrique le plus petit d’un cercle englobant la particule, λ la longueur d’onde la plus grande du spectre visible et np l’indice de réfraction optique du milieu dans lequel sont dispersées les nanoparticules.Nanostructured surface coating configured to generate visual appearances in a visible spectrum range, comprising: - a first layer comprising a random distribution of nanoparticles; a substrate, on which the first layer is arranged; the nanoparticles having an optical refraction index npart having a value suitable for each individually diffusing the incident light; the nanoparticles being arranged so that the mean distance between two adjacent particles d is defined in accordance with the following relationship so as to produce interference between the light diffused by the particles: 2 R ≤ d ≤ max (λ / np), where R is the smallest geometric radius of a circle surrounding the particle, λ is the greatest wavelength of the visible spectrum, and np is the optical refractive index of the medium in which the nanoparticles are dispersed

Quasinormal-mode analysis of grating spectra at fixed incidence angles

Grating spectra exhibit sharp variations of the scattered light, known as grating anomalies. The latter are due to resonances that have fascinated specialists of optics and physics for decades and are today used in many applications. We present a comprehensive theory of grating anomalies and develop a formalism to expand the field scattered by metallic or dielectric gratings into the basis of its natural resonances, thereby enabling the possibility to reconstruct grating spectra measured for fixed illumination angles as a sum over every individual resonance contribution with closed-form expressions. This gives physical insights into the spectral properties and direct access to the resonances to engineer the spectral response of gratings and their sensitivity to tiny perturbations

EMS mutagenesis in mature seed-derived rice calli as a new method for rapidly obtaining tilling mutant populations.

Background: TILLING (Targeting Induced Local Lesions IN Genomes) is a reverse genetic method that combines chemical mutagenesis with high-throughput genome-wide screening for point mutation detection in genes of interest. However, this mutation discovery approach faces a particular problem which is how to obtain a mutant population with a sufficiently high mutation density. Furthermore, plant mutagenesis protocols require two successive generations (M1, M2) for mutation fixation to occur before the analysis of the genotype can begin. Results: Here, we describe a new TILLING approach for rice based on ethyl methanesulfonate (EMS) mutagenesis of mature seed-derived calli and direct screening of in vitro regenerated plants. A high mutagenesis rate was obtained (i.e. one mutation in every 451 Kb) when plants were screened for two senescence-related genes. Screening was carried out in 2400 individuals from a mutant population of 6912. Seven sense change mutations out of 15 point mutations were identified. Conclusions: This new strategy represents a significant advantage in terms of time-savings (i.e. more than eight months), greenhouse space and work during the generation of mutant plant populations. Furthermore, this effective chemical mutagenesis protocol ensures high mutagenesis rates thereby saving in waste removal costs and the total amount of mutagen needed thanks to the mutagenesis volume reduction