Occurrence of iodinated X-ray contrast media in indirect potable reuse systems

A lack of knowledge of the health and environmental risks associated with chemicals of concern (COCs) and also of their removal by advanced treatment processes, such as micro-filtration (MF) and reverse osmosis (RO), have been major barriers preventing establishment of large water recycling schemes. As part of a larger project monitoring over 300 COCs, iodinated x-ray contrast media compounds (ICM) were analysed in treated secondary wastewater intended for drinking purposes. ICM are the most widely administered intravascular pharmaceuticals and are known to persist in the aquatic environment. A direct injection liquid chromatography tandem mass spectrometry (DI-LC-MS/MS) method was used to monitor secondary treated wastewater from three major wastewater treatment plants in Perth, Western Australia. In addition, tertiary water treated with MF and RO was analysed from a pilot plant that has been built as a first step in trialling the aquifer recharge. Results collected during 2007 demonstrate that MF/RO treatment is capable of removing ICM to below the analytical limits of detection, with average RO rejection calculated to be greater than 92%. A screening health risk assessment indicated negligible human risk at the concentrations observed in wastewater

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

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

A statistical model-based approach to unsupervised texture segmentation

The general problem of unsupervised textured segmentation remains a largely unsolved issue in image analysis . Many studies proved that statistical model based texture segmentation algorithms yield good reults provided that the model parameters and the number of regions are known a priori . In this paper the problem of determining the number of regions is addressed. The segmentation algorithm relies on the analysis of second and higher order spatial statistics of the original images. The segmentation map is represented using a Markov Random Field model and a bayesian estimate of this map is computed using a deterministic relaxation algorithm . The segmentation algorithm does only require the tuning of one parameter. Results on hand-drawn images of natural textures and real textured images show the capability of the model to yield relevant segmentations when the number of regions and the texture classes are not known a priori .La segmentation des images texturées constitue une étape préliminaire cruciale dans de nombreuses applications en analyse d'images. Les approches par modélisation statistique conduisent à de bons résultats dans ce domaine, lorsque les paramètres des modèles statistiques et le nombre de régions à extraire sont connus a priori. La segmentation non supervisée d'images texturées reste, par contre, un problème délicat, auquel aucune solution complète n'a été apportée jusqu'à present. Nous contribuons à cet effort, en proposant une méthode de segmentation ne nécessitant pas de connaissance a priori sur le nombre ou le type de textures présentes dans l'imag

EL PUERTO ENGALANADA PARA RECIBIR AL REY [Material gráfico]

Copia digital. Madrid : Ministerio de Educación, Cultura y Deporte. Subdirección General de Coordinación Bibliotecaria, 201

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

Theoretical study of finite temperature spectroscopy in van der Waals clusters. I. Probing phase changes in CaAr_n

The photoabsorption spectra of calcium-doped argon clusters CaAr_n are investigated at thermal equilibrium using a variety of theoretical and numerical tools. The influence of temperature on the absorption spectra is estimated using the quantum superposition method for a variety of cluster sizes in the range 6<=n<=146. At the harmonic level of approximation, the absorption intensity is calculated through an extension of the Gaussian theory by Wadi and Pollak [J. Chem. Phys. vol 110, 11890 (1999)]. This theory is tested on simple, few-atom systems in both the classical and quantum regimes for which highly accurate Monte Carlo data can be obtained. By incorporating quantum anharmonic corrections to the partition functions and respective weights of the isomers, we show that the superposition method can correctly describe the finite-temperature spectroscopic properties of CaAr_n systems. The use of the absorption spectrum as a possible probe of isomerization or phase changes in the argon cluster is discussed at the light of finite-size effects.Comment: 17 pages, 9 figure

Comparison of risk factors predicting return to work between patients with subacute and chronic non-specific low back pain: systematic review

The objective of the study was to provide an inventory of predictive instruments and their constituting parameters associated with return to work in patients with subacute (2-10weeks pain duration) and chronic (10-24weeks pain duration) non-specific low back pain (NSLBP). Data sources included systematic review in Medline, Embase, Cinahl, Central, PEDro, Psyndex, PsychInfo/PsycLit, and Sociofile up to September 2008, in reference lists of systematic reviews on risk factors, and of included studies. For the systematic review, two reviewers independently assessed study eligibility and quality, and extracted data. Disagreements were resolved by consensus. Risk factors were inventorised and grouped into a somatic and psychosocial domain. 23 studies reporting on subacute and 16 studies reporting on chronic patients were included. The studies on subacute patients reported on a total of 56 biomedical factors out of which 35 (63%) were modifiable and 61 psychosocial factors out of which 51 (84%) were modifiable. The corresponding values in studies on chronic patients were 44 biomedical [27 (62%) modifiable] and 61 [40 (66%) modifiable] respectively. Our data suggest that the interdisciplinary approach in patients at risk to develop persistent NSLBP is justified in both, the subacute and chronic disease stages. Psychosocial interventions might be more effective in subacute stages since a higher proportion of modifiable risk factors were identified in that grou