Wigner islands with electrons over helium

We present here the first experimental study of Wigner islands formed by electrons floating over helium. Electrons are trapped electrostatically in a mesoscopic structure covered with a helium film, behaving as a quantum dot. By removing electrons one by one, we are able to find the addition spectrum, i.e. the energy required to add (or extract) one electron from the trap with occupation number $N$. Experimental addition spectra are compared with Monte Carlo simulations for the actual trap geometry, confirming the ordered state of electrons over helium in the island.Comment: 12 pages, 13 figures, draft pape

A Reanalysis of theUltraviolet Extinction from Interstellar Dust in the Large Magellanic Cloud

We have reanalyzed the Large Magellanic Cloud's (LMC) ultraviolet (UV) extinction using data from the IUE final archive. Our new analysis takes advantage of the improved signal--to--noise of the IUE NEWSIPS reduction, the exclusion of stars with very low reddening, the careful selection of well matched comparison stars, and an analysis of the effects of Galactic foreground dust. Differences between the average extinction curves of the 30 Dor region and the rest of the LMC are reduced compared to previous studies. We find that there is a group of stars with very weak 2175 Ang. bumps that lie in or near the region occupied by the supergiant shell, LMC 2, on the southeast side of 30 Dor. The average extinction curves inside and outside LMC 2 show a very significant difference in 2175 Ang. bump strength, but their far--UV extinctions are similar. While it is unclear whether or not the extinction outside the LMC 2 region can be fit with the relation of Cardelli, Clayton and Mathis (CCM), sightlines near LMC 2 cannot be fit with CCM due to their weak 2175 Ang. bumps. While the extinction properties seen in the LMC lie within the range of properties seen in the Galaxy, the correlations of UV extinction properties with environment seen in the Galaxy do not appear to hold in the LMC.Comment: 29 pages, 10 figures, to be published in Ap

Instrumentation and digital image processing for multimodality imagery applied to seeds and seedlings

Instrumentation and digital image processing for multimodality imagery applied to seeds and seedlings

Suivi automatisé de l’allongement des plantules et intérêt des différentes modalités d’imagerie

Suivi automatisé de l’allongement des plantules et intérêt des différentes modalités d’imagerie

3D multimodal simulation of image acquisition by X-Ray and MRI for validation of seedling measurements with segmentation algorithms

3D multimodal simulation of image acquisition by X-Ray and MRI for validation of seedling measurements with segmentation algorithms

High-sensitivity optical monitoring of a micro-mechanical resonator with a quantum-limited optomechanical sensor

We experimentally demonstrate the high-sensitivity optical monitoring of a micro-mechanical resonator and its cooling by active control. Coating a low-loss mirror upon the resonator, we have built an optomechanical sensor based on a very high-finesse cavity (30000). We have measured the thermal noise of the resonator with a quantum-limited sensitivity at the 10^-19 m/rootHz level, and cooled the resonator down to 5K by a cold-damping technique. Applications of our setup range from quantum optics experiments to the experimental demonstration of the quantum ground state of a macroscopic mechanical resonator.Comment: 4 pages, 5 figure

The relations between work centrality, psychological contracts, and job attitudes: the influence of age

The current study sought to explain a largely overlooked theme in psychological contract literature, that is, how individual factors are related to formation of psychological contract. It investigated the relationship between people’s work centrality, psychological contracts, and job attitudes. It was expected that people with higher work centrality would be less likely to have a transactional contract and more likely to have a relational contract with the employer. Furthermore, it was expected that psychological contract (transactional and relational) would mediate the relations between work centrality and job attitudes. Finally, we expected age to moderate the relations between work centrality and the psychological contract. The study was conducted among 465 employees in a Dutch health care organization. Structural equation models supported the mediating effect of psychological contract types in the relations between work centrality and three job attitudes (work engagement, job satisfaction, and turnover intention). Moreover, it was found that the relations between work centrality and psychological contract were stronger for older workers than for younger workers

ElonCam : Système de vision pour mesurer la croissance des plantules en phase hétérotrophe

Système de vision pour mesurer la croissance des plantules en phase hétérotrophe

On the value of the Kullback-Leibler divergence for cost-effective spectral imaging of plants by optimal selection of wavebands

The practical value of a criterion based on statistical information theory is demonstrated for the selection of optimal wavelength and bandwidth of low-cost lighting systems in plant imaging applications. Kullback–Leibler divergence is applied to the problem of spectral band reduction from hyperspectral imaging. The results are illustrated on various plant imaging problems and show similar results to the one obtained with state-of-the-art criteria. A specific interest of the proposed approach is to offer the possibility to integrate technological constraints in the optimization of the spectral bands selected