Jose Luis Santiago

Dense genotyping identifies and localizes multiple common and rare variant association signals in celiac disease.

Using variants from the 1000 Genomes Project pilot European CEU dataset and data from additional resequencing studies, we densely genotyped 183 non-HLA risk loci previously associated with immune-mediated diseases in 12,041 individuals with celiac disease (cases) and 12,228 controls. We identified 13 new celiac disease risk loci reaching genome-wide significance, bringing the number of known loci (including the HLA locus) to 40. We found multiple independent association signals at over one-third of these loci, a finding that is attributable to a combination of common, low-frequency and rare genetic variants. Compared to previously available data such as those from HapMap3, our dense genotyping in a large sample collection provided a higher resolution of the pattern of linkage disequilibrium and suggested localization of many signals to finer scale regions. In particular, 29 of the 54 fine-mapped signals seemed to be localized to single genes and, in some instances, to gene regulatory elements. Altogether, we define the complex genetic architecture of the risk regions of and refine the risk signals for celiac disease, providing the next step toward uncovering the causal mechanisms of the disease.

COST 732 in practice: the MUST model evaluation exercise

The aim of this paper is to describe the use of a general methodology tailored to the evaluation of micro-scale meteorological models applied to flow and dispersion simulations in urban areas. This methodology, developed within COST 732, has been tested through a large modelling exercise involving many groups across Europe. The major test case used is the Mock Urban Setting Test (MUST) experiment representing an idealised urban area. It is emphasised that a full model evaluation is problem-dependent and requires several activities including a statistical validation that requires a careful choice of the metrics for the comparison with measurements.

A computational fluid dynamic modelling approach to assess the representativeness of urban monitoring stations

Air quality measurements of urban monitoring stations have a limited spatial representativeness due to the complexity of urban meteorology and emissions distribution. In this work, a methodology based on a set of computational fluid dynamics simulations based on Reynolds-Averaged Navier-Stokes equations (RANS-CFD) for different meteorological conditions covering several months is developed in order to analyse the spatial representativeness of urban monitoring stations and to complement their measured concentrations. The methodology has been applied to two urban areas nearby air quality traffic-oriented stations in Pamplona and Madrid (Spain) to analyse nitrogen oxides concentrations. The computed maps of pollutant concentrations around each station show strong spatial variability being very difficult to comply with the European legislation concerning the spatial representativeness of traffic-oriented air quality stations.

Evaluation of a CFD-based approach to estimate pollutant distribution within a real urban canopy by means of passive samplers.

The distribution of pollutants is spatially heterogeneous within urban streets making difficult to build a realistic concentration map. In this paper, a methodology based on computational fluid dynamic modeling with Reynolds-averaged Navier-Stokes approach is used to compute maps of concentration for a period of several weeks. The methodology is evaluated by comparing simulation results against experimental data from two different campaigns where a large number of passive samplers deployed in an area with heavy vehicular traffic in Madrid (Spain). The evaluation shows that the methodology is able to reproduce the general pattern of several-week averaged pollutant distribution in an urban area with heavy vehicular traffic, resolving the spatial variability up to a resolution of 1-2m. In addition, the model results fit satisfactorily the time evolution of the pollutant concentration measured at an air quality station deployed in the studied area. However, problems were detected close to zones with complex emissions patterns (tunnels, street forks, etc.), where the model compared poorly against passive sampler measurements. A preliminary assessment of the uncertainties induced in the numerical methodology due to consider NO2 as non-reactive pollutant under winter conditions indicates that it would be an acceptable approach for this particular case study. Overall, our analysis contributes to raise the confidence in that approached similar to the one presented in this study can be adopted for dealing with several aspects of the air quality management such as air quality assessment, optimization of the location of measurement stations, and the evaluation of air pollution reduction strategies.

Modelling the air flow in symmetric and asymmetric street canyons

The main objective of this paper is to describe flow features in sequences of two-dimensional street canyons. Several configurations of symmetric and asymmetric canyons are studied by CFD modelling. Streets with different aspect ratios (W/H), where W is the width of street and H is the building height, are investigated. In asymmetric situations, one building (in the central canyon) is taller (30 m) than the others (20 m). The presence of the taller building seems to have a large influence on the wind flow inside the central street canyon and in ones located downstream. These results show that simulations are Reynolds-independent.

Streamwise Versus Spanwise Spacing of Obstacle Arrays: Parametrization of the Effects on Drag and Turbulence

A Reynolds-averaged Navier–Stokes model is used to investigate the evolution of the sectional drag coefficient and turbulent length scales with the layouts of aligned arrays of cubes. Results show that the sectional drag coefficient is determined by the non-dimensional streamwise distance (sheltering parameter), and the non-dimensional spanwise distance (channelling parameter) between obstacles. This is different than previous approaches that consider only plan area density

Application of a short term air quality action plan in Madrid (Spain) under a high-pollution episode - Part II: Assessment from multi-scale modelling

(\lambda _\mathrm{p})

CFD modelling of air quality in Pamplona City (Spain): Assessment, stations spatial representativeness and health impacts valuation

(λp). On the other hand, turbulent length scales behave similarly to the staggered case (e. g. they are function of