Lagrangian and Eulerian dataset of the wake downstream of a smooth cylinder at a Reynolds number equal to 3900.

The dataset contains Eulerian velocity and pressure fields, and Lagrangian particle trajectories of the wake flow downstream of a smooth cylinder at a Reynolds number equal to 3900. An open source Direct Numerical Simulation (DNS) flow solver named Incompact3d was used to calculate the Eulerian field around the cylinder. The synthetic Lagrangian tracer particles were transported using a fourth-order Runge-Kutta scheme in time and trilinear interpolations in space. Trajectories of roughly 200,000 particles for two 3D sub-domains are available to the public. This dataset can be used as a test case for tracking algorithm assessment, exploring the Lagrangian physics, statistic analyses, machine learning, and data assimilation interests

Halogen-specific total organic halogen analysis: Assessment by recovery of total bromine

Determination of halogen-specific total organic halogen (TOX) is vital for studies of disinfection of waters containing bromide, since total organic bromine (TOBr) is likely to be more problematic than total organic chlorine. Here, we present further halogen-specific TOX method optimisation and validation, focusing on measurement of TOBr. The optimised halogen-specific TOX method was validated based on the recovery of model compounds covering different classes of disinfection by-products (haloacetic acids, haloacetonitriles, halophenols and halogenated benzenes) and the recovery of total bromine (mass balance of TOBr and bromide concentrations) during disinfection of waters containing dissolved organic matter and bromide. The validation of a halogen-specific TOX method based on the mass balance of total bromine has not previously been reported. Very good recoveries of organic halogen from all model compounds were obtained, indicating high or complete conversion of all organic halogen in the model compound solution through to halide in the absorber solution for ion chromatography analysis. The method was also successfully applied to monitor conversion of bromide to TOBr in a groundwater treatment plant. An excellent recovery (101%) of total bromine was observed from the raw water to the post-chlorination stage. Excellent recoveries of total bromine (92%–95%) were also obtained from chlorination of a synthetic water containing dissolved organic matter and bromide, demonstrating the validity of the halogen-specific TOX method for TOBr measurement. The halogen-specific TOX method is an important tool to monitor and better understand the formation of halogenated organic compounds, in particular brominated organic compounds, in drinking water systems

Multiband theory of multi-exciton complexes in self-assembled quantum dots

We report on a multiband microscopic theory of many-exciton complexes in self-assembled quantum dots. The single particle states are obtained by three methods: single-band effective-mass approximation, the multiband $k\cdot p$ method, and the tight-binding method. The electronic structure calculations are coupled with strain calculations via Bir-Pikus Hamiltonian. The many-body wave functions of $N$ electrons and $N$ valence holes are expanded in the basis of Slater determinants. The Coulomb matrix elements are evaluated using statically screened interaction for the three different sets of single particle states and the correlated $N$-exciton states are obtained by the configuration interaction method. The theory is applied to the excitonic recombination spectrum in InAs/GaAs self-assembled quantum dots. The results of the single-band effective-mass approximation are successfully compared with those obtained by using the of $k\cdot p$ and tight-binding methods.Comment: 10 pages, 8 figure

Determination of sixteen polycyclic aromatic hydrocarbons in aqueous and solid samples from an Italian wastewater treatment plant

This study addresses the issue of whether it is possible to accurately predict the removalefficiencies of metals of environmental concern (i.e., Al, Ag, As, B, Ba, Cd, Cr, Fe, Mn, Hg, Ni,Pb, Cu, V, and Zn) in a wastewater treatment plant. The plant in question (at Fusina, Venice,Italy) is fed by mixed wastes from municipal and industrial sources (300 000 equivalentinhabitants) and discharges the treated effluent into the Venice lagoon. The year-long samplingcampaign (2001-2002) yielded a substantial amount of analytical data and relatively wide rangesof concentrations of metals in the influent samples, which made it possible to study the removalefficiencies by plotting the terms (inlet concentration - outlet concentration) vs (inlet concentration)for each metal investigated. The data in the plots were fitted using the linear regressionmodel Y ) BX. The slope rates (terms B), which were estimated by the least-squares method,have been adopted as the removal efficiencies, and they can be considered as constants in theconcentration ranges recorded in this work. The relative abundance of metals in the rawwastewaters feeding Fusina WWTP followed the order Al > Fe > B > Zn > Ba > Mn > Cu >Pb > Hg ) Ni > Cr ) As > V > Ag > Cd, while in the effluent the order was Fe > Al > Zn >Mn > Ba > Ni > Cu > Pb > Cr > Ag > As > Hg ) V > Cd. The removal percentages (%) of themetals were Al ) 92 ( 1; Ag ) 94 ( 1; As ) 76 ( 3; B ) n.d.; Ba ) 85 ( 2; Cd ) 85 ( 2; Cr )87 ( 1; Fe ) 90 ( 1; Mn ) 61 ( 2; Hg ) 93 ( 1; Ni ) 50 ( 3; Pb ) 92 ( 1; Cu ) 93 ( 1; V )74 ( 2; and Zn ) 75 ( 3

Exciton and negative trion dissociation by an external electric field in vertically coupled quantum dots

We study the Stark effect for an exciton confined in a pair of vertically coupled quantum dots. A single-band approximation for the hole and a parabolic lateral confinement potential are adopted which allows for the separation of the lateral center-of-mass motion and consequently for an exact numerical solution of the Schr\"odinger equation. We show that for intermediate tunnel coupling the external electric field leads to the dissociation of the exciton via an avoided crossing of bright and dark exciton energy levels which results in an atypical form of the Stark shift. The electric-field-induced dissociation of the negative trion is studied using the approximation of frozen lateral degrees of freedom. It is shown that in a symmetric system of coupled dots the trion is more stable against dissociation than the exciton. For an asymmetric system of coupled dots the trion dissociation is accompanied by a positive curvature of the recombination energy line as a function of the electric field.Comment: PRB - in prin

Effect of quantum confinement on exciton-phonon interactions

We investigate the homogeneous linewidth of localized type-I excitons in type-II GaAs/AlAs superlattices. These localizing centers represent the intermediate case between quasi-two-dimensional (Q2D) and quasi-zero-dimensional localizations. The temperature dependence of the homogeneous linewidth is obtained with high precision from micro-photoluminescence spectra. We confirm the reduced interaction of the excitons with their environment with decreasing dimensionality except for the coupling to LO-phonons. The low-temperature limit for the linewidth of these localized excitons is five times smaller than that of Q2D excitons. The coefficient of exciton-acoustic-phonon interaction is 5 ~ 6 times smaller than that of Q2D excitons. An enhancement of the average exciton-LO-phonon interaction by localization is found in our sample. But this interaction is very sensitive to the detailed structure of the localizing centers.Comment: 6 pages, 4 figure

Contextual Object Detection with a Few Relevant Neighbors

A natural way to improve the detection of objects is to consider the contextual constraints imposed by the detection of additional objects in a given scene. In this work, we exploit the spatial relations between objects in order to improve detection capacity, as well as analyze various properties of the contextual object detection problem. To precisely calculate context-based probabilities of objects, we developed a model that examines the interactions between objects in an exact probabilistic setting, in contrast to previous methods that typically utilize approximations based on pairwise interactions. Such a scheme is facilitated by the realistic assumption that the existence of an object in any given location is influenced by only few informative locations in space. Based on this assumption, we suggest a method for identifying these relevant locations and integrating them into a mostly exact calculation of probability based on their raw detector responses. This scheme is shown to improve detection results and provides unique insights about the process of contextual inference for object detection. We show that it is generally difficult to learn that a particular object reduces the probability of another, and that in cases when the context and detector strongly disagree this learning becomes virtually impossible for the purposes of improving the results of an object detector. Finally, we demonstrate improved detection results through use of our approach as applied to the PASCAL VOC and COCO datasets

Klebsiella pneumonia strains moderately resistant to ampicillin and carbenicillin: characterization of a new β-lactamase

Klebsiella pneumoniae strain 11-03, moderately resistant to ampicillin and carbenicillin, produces one constitutive β-lactamase with an isoelectric point of 7.10 and a molecular weight of 20,000±500. The enzymatic activity is directed primarily against the penicillins, ampicillin being the best substrate. Some cephalosporins are also hydrolyzed to some extent but the affinity of the enzyme for these antibiotics is low (high Km values). It has not been possible to determine whether the biogenesis of this β-lactamase is mediated by the bacterial chromosome or by a non-transferable plasmid. This β-lactamase appears to be different, on the basis of isoelectricfocusing, from an enzyme produced by the K pneumoniae strain GN422 (Sawal et al, 1973), but similar to the latter in several propertie