Large-Eddy Simulation of Flow and Pollutant Transport in Urban Street Canyons with Ground Heating

Our study employed large-eddy simulation (LES) based on a one-equation subgrid-scale model to investigate the flow field and pollutant dispersion characteristics inside urban street canyons. Unstable thermal stratification was produced by heating the ground of the street canyon. Using the Boussinesq approximation, thermal buoyancy forces were taken into account in both the Navier–Stokes equations and the transport equation for subgrid-scale turbulent kinetic energy (TKE). The LESs were validated against experimental data obtained in wind-tunnel studies before the model was applied to study the detailed turbulence, temperature, and pollutant dispersion characteristics in the street canyon of aspect ratio 1. The effects of different Richardson numbers (Ri) were investigated. The ground heating significantly enhanced mean flow, turbulence, and pollutant flux inside the street canyon, but weakened the shear at the roof level. The mean flow was observed to be no longer isolated from the free stream and fresh air could be entrained into the street canyon at the roof-level leeward corner. Weighed against higher temperature, the ground heating facilitated pollutant removal from the street canyon.Singapore-MIT Alliance for Research and Technology. Center for Environmental Sensing and Monitorin

Validation of the Finnish version of the SCOFF questionnaire among young adults aged 20 to 35 years

<p>Abstract</p> <p>Background</p> <p>We tested the validity of the SCOFF, a five-question screening instrument for eating disorders, in a general population sample.</p> <p>Methods</p> <p>A random sample of 1863 Finnish young adults was approached with a questionnaire that contained several screens for mental health interview, including the SCOFF. The questionnaire was returned by 1316 persons. All screen positives and a random sample of screen negatives were invited to SCID interview. Altogether 541 subjects participated in the SCID interview and had filled in the SCOFF questionnaire. We investigated the validity of the SCOFF in detecting current eating disorders by calculating sensitivity, specificity, and positive and negative predictive values (PPV and NPV) for different cut-off scores. We also performed a ROC analysis based on these 541 persons, of whom nine had current eating disorder.</p> <p>Results</p> <p>The threshold of two positive answers presented the best ability to detect eating disorders, with a sensitivity of 77.8%, a specificity of 87.6%, a PPV of 9.7%, and a NPV of 99.6%. None of the subjects with current eating disorder scored zero points in the SCOFF.</p> <p>Conclusion</p> <p>Due to its low PPV, there are limitations in using the SCOFF as a screening instrument in unselected population samples. However, it might be used for ruling out the possibility of eating disorders.</p

Crk and CrkL adaptor proteins: networks for physiological and pathological signaling

The Crk adaptor proteins (Crk and CrkL) constitute an integral part of a network of essential signal transduction pathways in humans and other organisms that act as major convergence points in tyrosine kinase signaling. Crk proteins integrate signals from a wide variety of sources, including growth factors, extracellular matrix molecules, bacterial pathogens, and apoptotic cells. Mounting evidence indicates that dysregulation of Crk proteins is associated with human diseases, including cancer and susceptibility to pathogen infections. Recent structural work has identified new and unusual insights into the regulation of Crk proteins, providing a rationale for how Crk can sense diverse signals and produce a myriad of biological responses

Numerical modelling of microclimatic conditions within the vicinity of buildings

International audienc

Numerical model inter-comparison for a single block building within ATREUS

International audienc

The modelling of traffic produced turbulence

The chapter summarises the results of the TRAPOS working group “Traffic Produced Turbulence” (TPT). The main goals of these working group have been i) to summarise the TPT results that had already been achieved by the different teams, ii) to exchange the views and knowledge regarding TPT effects iii) to find a consensus concerning the relevance of traffic produced turbulence for dispersion modelling, iv) to improve TPT scaling concepts v) to verify TPT parameterisations for numerical dispersion models and vi) to present concepts for an incorporation of TPT effects in regulatory dispersion models. The studies performed within the TRAPOS TPT working group have shown that TPT is an important aspect for dispersion of traffic emissions. Neglecting TPT parameterisations in dispersion models causes significant over-predictions of pollutant concentrations in urban street canyons that range up to a factor of 4 to 5. Empirical formulas like the so-called VDI method lead to improvements, but operationally significant differences between model calculations and measured concentration values still occur for above-roof wind speeds smaller than approximately 4-5 m/s. Based on the findings of the TRAPOS TPT working group the following recommendations are made for practical applications of dispersion models: The TPT parameterisation implemented in the OSPM model works satisfactorily and dispersion models similar to OSPM should include the OSPM TPT concept. The traditional velocity scaling of concentrations and the empirical VDI method have deficiencies and must be reconsidered. The approach presented in Kastner-Klein et al. (2001) and Ketzel et al. (2001) that is based on a velocity scale which is defined as composition of velocity variances due to the external flow and due to traffic motions is an improvement and can be recommended. In CFD models TPT parameterisations must be implemented and the developed concepts are an improvement compared to model calculations without TPT parameterisations. However, for recommendations of particular modifications in the system of equations further verification studies are necessary