Influence of chirping the Raman lasers in an atom gravimeter: phase shifts due to the Raman light shift and to the finite speed of light

We present here an analysis of the influence of the frequency dependence of the Raman laser light shifts on the phase of a Raman-type atom gravimeter. Frequency chirps are applied to the Raman lasers in order to compensate gravity and ensure the resonance of the Raman pulses during the interferometer. We show that the change in the Raman light shift when this chirp is applied only to one of the two Raman lasers is enough to bias the gravity measurement by a fraction of $\mu$Gal ($1~\mu$Gal~=~$10^{-8}$~m/s$^2$). We also show that this effect is not compensated when averaging over the two directions of the Raman wavevector $k$. This thus constitutes a limit to the rejection efficiency of the $k$-reversal technique. Our analysis allows us to separate this effect from the effect of the finite speed of light, which we find in perfect agreement with expected values. This study highlights the benefit of chirping symmetrically the two Raman lasers

Maximum growth and decay rates of autotrophic biomass to simulate nitrogen removal at 10°C with municipal activated sludge plants

The present study aims at determining most likely values for the maximum growth rate (μA, max) and the endogenous decay rate (bA) of nitrifiers for activated sludge processes treating municipal wastewater operated at low temperature (10°C). The work used nitrification rate data measured on 10 full-scale plants and 2 pilot plants fed with domestic sewage. This set of data was combined with a modelling and a theoretical approach. The unified values (μA, max = 0.45·d-1 and bA = 0.13·d-1) were obtained at 10°C for the kinetic parameters of the autotrophic biomass in the SRT range 10 to 50 d. In addition, the factors affecting the expected nitrification rate (rv, nit) were established by a theoretical approach and confirmed by experimental results. For a given SRT, a linear relationship with the nitrogen volumetric loading rate was shown. The COD/TKN ratio of the influent on the nitrification rate was demonstrated. Finally, an operational tool for the verification of the nitrification rate in the design procedure of activated sludge processes is proposed.Keywords: nitrification; kinetics; low temperature; autotrophic biomass, maximum growth rate; decay rat

Anoxic and aerobic values for the yield coefficient of the heterotrophic biomass: Determination at full-scale plants and consequences on simulations

The present study aims at optimising the nitrification and denitrification phases at intermittently aerated process (activated sludge) removing nitrogen from municipal wastewater. The nitrogen removal performance recorded at 22 intermittently aerated plants was compared to the results obtained from the simulations given by the widely used ASM1. It is shown that simulations with a single value for the heterotrophic yield with any electron acceptor over-predict the nitrate concentration in the effluent of treatment plants. The reduction of this coefficient by 20% for anoxic conditions reduces the nitrate concentration by 10 g N·m-3. It significantly improves the accuracy of the predictions of nitrate concentrations in treatedeffluents compare to real data. Simulations with dual values (aerobic and anoxic conditions) for heterotrophic yield (modified ASM1) were then used to determine the practical daily aerobic time interval to meet a given nitrogen discharge objective. Finally, to support design decisions, the relevance of a pre-denitrification configuration in front of an intermittently aerated tank was studied. It is shown that when the load of BOD5 is below the conventional design value, a small contribution of the anoxic zone to nitrate removal occurs, except for over-aerated plants. When plants receive a higher load of BOD5, the modified ASM1 suggests that the anoxic zone has a higher contribution to nitrogen removal, for both correctly and over-aerated plants

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 $\sim 0.1-10$ 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

Relationship Between LIBS Ablation and Pit Volume for Geologic Samples: Applications for the In Situ Absolute Geochronology

These first results demonstrate that LIBS spectra can be an interesting tool to estimate the ablated volume. When the ablated volume is bigger than 9.10(exp 6) cubic micrometers, this method has less than 10% of uncertainties. Far enough to be directly implemented in the KArLE experiment protocol. Nevertheless, depending on the samples and their mean grain size, the difficulty to have homogeneous spectra will increase with the ablated volume. Several K-Ar dating studies based on this approach will be implemented. After that, the results will be shown and discussed

X-Ray Microanalysis of Calcium Containing Organelles in Resin Embedded Tissue

The localization of calcium in cell organelles at the electron microscope level is often achieved through cytochemical techniques, and verified by X-ray microanalysis. Various methods have been used to cytochemically detect calcium or calcium-binding sites : calcium loading, calcium substitution by strontium, barium, or even lead, and calcium precipitation by oxalate, phosphate, fluoride, or pyroantimonate. Their results may have heuristic value, particularly in preliminary studies of poorly known cell types. A complementary and more physiological approach is offered by quantitative measurement of the total calcium content of organelles after cryofixation. Resin embedding is less demanding than cryomicrotomy and gives better images : it can be used after cryosubstitution in the presence of oxalic acid. This technique was tested, and applied to several cell types

PCI - HIPPI Interface Modules

Interface modules between PCI local bus and HIPPI are described. The modules are intended to aid the implementation of the high performance computer network. the aimed maximum throughput of the interface module is 100MBytes/sec while sustained data transfer rate depends of the particular system performance

Properties of Electrodeposited CuSCN 2D Layers and Nanowires Influenced by Their Mixed Domain Structure

International audienc

Comparisons of the factor structure and measurement invariance of the Spence children’s anxiety scale - parent version in children with autism spectrum disorder and typically developing anxious children

The Spence Children’s Anxiety Scale - Parent version (SCAS-P) is often used to assess anxiety in children with autism spectrum disorder (ASD), however, little is known about the validity of the tool in this population. The aim of this study was to determine whether the SCAS-P has the same factorial validity in a sample of young people with ASD (n=285), compared to a sample of typically developing young people with anxiety disorders (n=224). Poor model fit with all of the six hypothesised models precluded invariance testing. Exploratory factor analysis indicated that different anxiety phenomenology characterises the two samples. The findings suggest that cross-group comparisons between ASD and anxious samples based on the SCAS-P scores may not always be appropriat