Relative humidity impact on aerosol parameters in a Paris suburban area

Measurements of relative humidity (RH) and aerosol parameters (scattering cross section, size distributions and chemical composition), performed in ambient atmospheric conditions, have been used to study the influence of relative humidity on aerosol properties. The data were acquired in a suburban area south of Paris, between 18 and 24 July 2000, in the framework of the 'Etude et Simulation de la Qualit&#233; de l'air en Ile-de-France' (ESQUIF) program. According to the origin of the air masses arriving over the Paris area, the aerosol hygroscopicity is more or less pronounced. The aerosol chemical composition data were used as input of a thermodynamic model to simulate the variation of the aerosol water mass content with ambient <i>RH</i> and to determine the main inorganic salt compounds. The coupling of observations and modelling reveals the presence of deliquescence processes with hysteresis phenomenon in the hygroscopic growth cycle. Based on the H&#228;nel model, parameterisations of the scattering cross section, the modal radius of the accumulation mode of the size distribution and the aerosol water mass content, as a function of increasing RH, have been assessed. For the first time, a crosscheck of these parameterisations has been performed and shows that the hygroscopic behaviour of the accumulation mode can be coherently characterized by combined optical, size distribution and chemical measurements

A quasi-monomode guided atom-laser from an all-optical Bose-Einstein condensate

We report the achievement of an optically guided and quasi-monomode atom laser, in all spin projection states ($m_F =$ -1, 0 and $+1$) of F=1 in Rubidium 87. The atom laser source is a Bose-Einstein condensate (BEC) in a crossed dipole trap, purified to any one spin projection state by a spin-distillation process applied during the evaporation to BEC. The atom laser is outcoupled by an inhomogenous magnetic field, applied along the waveguide axis. The mean excitation number in the transverse modes is $= 0.65 \pm 0.05$ for $m_F = 0$ and $= 0.8 \pm 0.3$ for the low field seeker $m_F = -1$

Optimal transport of ultracold atoms in the non-adiabatic regime

We report the transport of ultracold atoms with optical tweezers in the non-adiabatic regime, i.e. on a time scale on the order of the oscillation period. We have found a set of discrete transport durations for which the transport is not accompanied by any excitation of the centre of mass of the cloud. We show that the residual amplitude of oscillation of the dipole mode is given by the Fourier transform of the velocity profile imposed to the trap for the transport. This formalism leads to a simple interpretation of our data and simple methods for optimizing trapped particles displacement in the non-adiabatic regime

Study of different membrane spargers used in waste water treatment : characterisation and performance

In urban waste water treatment, a novel gas sparger based on flexible rubber membrane has been used for the last ten years. The objective of this present work is to compare two flexible membranes (the new membrane and the old membrane provided by ONDEO-DEGREMONT group) used in waste water treatment. For this purpose, the different membrane properties (hole diameter, pressure drop, critical pressure, deflection at the centerline and elasticity) have been characterized. The bubble generation at the membranes with a single orifice and with four orifices have been studied and their performances have been compared in terms of interfacial area and power consumption. From the experimental and theoretical approach, the new membrane is less elastic (or more rigid) than the old membrane. The bubble diameters generated from the new membrane remain constant with the gas velocity through the orifice, whereas they increase logarithmically for the old membrane. The inverse behaviours are observed in terms of the bubble formation frequency. Moreover, the bubbles generated from the new membrane have significantly larger sizes and lower formation frequencies than those obtained with the old one. From these results, it can be noted that the new membrane has a behaviour comparable to a rigid orifice. No coalescence phenomenon at the bubble formation is observed from the new and the old membranes with four orifices. The interfacial area and the power consumption are evaluated and show slight differences between the interfacial area provided by the old and the new membranes for one value of power consumption

Transport and interaction blockade of cold bosonic atoms in a triple-well potential

We theoretically investigate the transport properties of cold bosonic atoms in a quasi one-dimensional triple-well potential that consists of two large outer wells, which act as microscopic source and drain reservoirs, and a small inner well, which represents a quantum-dot-like scattering region. Bias and gate "voltages" introduce a time-dependent tilt of the triple-well configuration, and are used to shift the energetic level of the inner well with respect to the outer ones. By means of exact diagonalization considering a total number of six atoms in the triple-well potential, we find diamond-like structures for the occurrence of single-atom transport in the parameter space spanned by the bias and gate voltages. We discuss the analogy with Coulomb blockade in electronic quantum dots, and point out how one can infer the interaction energy in the central well from the distance between the diamonds.Comment: 18 pages, 6 figure

A quadrature filter approach for registration accuracy assessment of fundus images

This paper presents a method to automatically assess the accuracy of image registration. It is applicable to images in which vessels are the main landmarks such as fundus images and angiography. The method simultaneously exploits not only the position, but also the intensity profile across the vasculatures. The accuracy measure is defined as the energy of the odd component of the 1D vessel profile in the difference image divided by the total energy of the corresponding vessels in the constituting images. Scale and orientation-selective quadrature filter banks have been employed to analyze the 1D signal profiles. Subsequently, the relative energy measure has been calibrated such that the measure translates to a spatial misalignment in pixels. The method was validated on a fundus image dataset from a diabetic retinopathy screening program at the Rotterdam Eye Hospital. An evaluation showed that the proposed measure assesses the registration accuracy with a bias of -0.1 pixels and a precision (standard deviation) of 0.9 pixels. The small Fourier footprint of the orientation selective quadrature filters makes the method robust against noise

Long range transport of ultra cold atoms in a far-detuned 1D optical lattice

We present a novel method to transport ultra cold atoms in a focused optical lattice over macroscopic distances of many Rayleigh ranges. With this method ultra cold atoms were transported over 5 cm in 250 ms without significant atom loss or heating. By translating the interference pattern together with the beam geometry the trap parameters are maintained over the full transport range. Thus, the presented method is well suited for tightly focused optical lattices that have sufficient trap depth only close to the focus. Tight focusing is usually required for far-detuned optical traps or traps that require high laser intensity for other reasons. The transport time is short and thus compatible with the operation of an optical lattice clock in which atoms are probed in a well designed environment spatially separated from the preparation and detection region.Comment: 14 pages, 6 figure

Engineered swift equilibration of a Brownian particle

A fundamental and intrinsic property of any device or natural system is its relaxation time relax, which is the time it takes to return to equilibrium after the sudden change of a control parameter [1]. Reducing $tau$ relax , is frequently necessary, and is often obtained by a complex feedback process. To overcome the limitations of such an approach, alternative methods based on driving have been recently demonstrated [2, 3], for isolated quantum and classical systems [4--9]. Their extension to open systems in contact with a thermostat is a stumbling block for applications. Here, we design a protocol,named Engineered Swift Equilibration (ESE), that shortcuts time-consuming relaxations, and we apply it to a Brownian particle trapped in an optical potential whose properties can be controlled in time. We implement the process experimentally, showing that it allows the system to reach equilibrium times faster than the natural equilibration rate. We also estimate the increase of the dissipated energy needed to get such a time reduction. The method paves the way for applications in micro and nano devices, where the reduction of operation time represents as substantial a challenge as miniaturization [10]. The concepts of equilibrium and of transformations from an equilibrium state to another, are cornerstones of thermodynamics. A textbook illustration is provided by the expansion of a gas, starting at equilibrium and expanding to reach a new equilibrium in a larger vessel. This operation can be performed either very slowly by a piston, without dissipating energy into the environment, or alternatively quickly, letting the piston freely move to reach the new volume

Characterization of novel isoforms and evaluation of SNF2L/SMARCA1 as a candidate gene for X-linked mental retardation in 12 families linked to Xq25-26

<p>Abstract</p> <p>Background</p> <p>Mutations in genes whose products modify chromatin structure have been recognized as a cause of X-linked mental retardation (XLMR). These genes encode proteins that regulate DNA methylation (<it>MeCP2</it>), modify histones (<it>RSK2 </it>and <it>JARID1C</it>), and remodel nucleosomes through ATP hydrolysis (<it>ATRX</it>). Thus, genes encoding other chromatin modifying proteins should also be considered as disease candidate genes. In this work, we have characterized the <it>SNF2L </it>gene, encoding an ATP-dependent chromatin remodeling protein of the ISWI family, and sequenced the gene in patients from 12 XLMR families linked to Xq25-26.</p> <p>Methods</p> <p>We used an <it>in silico </it>and RT-PCR approach to fully characterize specific SNF2L isoforms. Mutation screening was performed in 12 patients from individual families with syndromic or non-syndromic XLMR. We sequenced each of the 25 exons encompassing the entire coding region, complete 5' and 3' untranslated regions, and consensus splice-sites.</p> <p>Results</p> <p>The <it>SNF2L </it>gene spans 77 kb and is encoded by 25 exons that undergo alternate splicing to generate several distinct transcripts. Specific isoforms are generated through the alternate use of exons 1 and 13, and by the use of alternate donor splice sites within exon 24. Alternate splicing within exon 24 removes a NLS sequence and alters the subcellular distribution of the SNF2L protein. We identified 3 single nucleotide polymorphisms but no mutations in our 12 patients.</p> <p>Conclusion</p> <p>Our results demonstrate that there are numerous splice variants of SNF2L that are expressed in multiple cell types and which alter subcellular localization and function. <it>SNF2L </it>mutations are not a cause of XLMR in our cohort of patients, although we cannot exclude the possibility that regulatory mutations might exist. Nonetheless, <it>SNF2L </it>remains a candidate for XLMR localized to Xq25-26, including the Shashi XLMR syndrome.</p

Characterization of novel isoforms and evaluation of SNF2L/SMARCA1 as a candidate gene for X-linked mental retardation in 12 families linked to Xq25-26

<p>Abstract</p> <p>Background</p> <p>Mutations in genes whose products modify chromatin structure have been recognized as a cause of X-linked mental retardation (XLMR). These genes encode proteins that regulate DNA methylation (<it>MeCP2</it>), modify histones (<it>RSK2 </it>and <it>JARID1C</it>), and remodel nucleosomes through ATP hydrolysis (<it>ATRX</it>). Thus, genes encoding other chromatin modifying proteins should also be considered as disease candidate genes. In this work, we have characterized the <it>SNF2L </it>gene, encoding an ATP-dependent chromatin remodeling protein of the ISWI family, and sequenced the gene in patients from 12 XLMR families linked to Xq25-26.</p> <p>Methods</p> <p>We used an <it>in silico </it>and RT-PCR approach to fully characterize specific SNF2L isoforms. Mutation screening was performed in 12 patients from individual families with syndromic or non-syndromic XLMR. We sequenced each of the 25 exons encompassing the entire coding region, complete 5' and 3' untranslated regions, and consensus splice-sites.</p> <p>Results</p> <p>The <it>SNF2L </it>gene spans 77 kb and is encoded by 25 exons that undergo alternate splicing to generate several distinct transcripts. Specific isoforms are generated through the alternate use of exons 1 and 13, and by the use of alternate donor splice sites within exon 24. Alternate splicing within exon 24 removes a NLS sequence and alters the subcellular distribution of the SNF2L protein. We identified 3 single nucleotide polymorphisms but no mutations in our 12 patients.</p> <p>Conclusion</p> <p>Our results demonstrate that there are numerous splice variants of SNF2L that are expressed in multiple cell types and which alter subcellular localization and function. <it>SNF2L </it>mutations are not a cause of XLMR in our cohort of patients, although we cannot exclude the possibility that regulatory mutations might exist. Nonetheless, <it>SNF2L </it>remains a candidate for XLMR localized to Xq25-26, including the Shashi XLMR syndrome.</p