An assessment of a three-beam Doppler lidar wind profiling method for use in urban areas

Currently there are few observations of the urban wind field at heights other than rooftop level. Remote sensing instruments such as Doppler lidars provide wind speed data at many heights, which would be useful in determining wind loadings of tall buildings, and predicting local air quality. Studies comparing remote sensing with traditional anemometers carried out in flat, homogeneous terrain often use scan patterns which take several minutes. In an urban context the flow changes quickly in space and time, so faster scans are required to ensure little change in the flow over the scan period. We compare 3993 h of wind speed data collected using a three-beam Doppler lidar wind profiling method with data from a sonic anemometer (190 m). Both instruments are located in central London, UK; a highly built-up area. Based on wind profile measurements every 2 min, the uncertainty in the hourly mean wind speed due to the sampling frequency is 0.05–0.11 m s−1. The lidar tended to overestimate the wind speed by ≈0.5 m s−1 for wind speeds below 20 m s−1. Accuracy may be improved by increasing the scanning frequency of the lidar. This method is considered suitable for use in urban areas

First results of an Hα based search of classical Be stars in the Perseus Arm and beyond

We investigate a region of the Galactic plane, between 120° ≤ l ≤ 140° and-1° ≤ b≤+4°, and uncover a population of moderately reddened (E(B-V) ~ 1) classical Be stars within and beyond the Perseus and Outer Arms. 370 candidate emission-line stars (13≲r≲16) selected from the Isaac Newton Telescope Photometric Ha Survey of the Northern Galactic plane have been followed up spectroscopically. A subset of these, 67 stars with properties consistent with those of classical Be stars, have been observed at sufficient spectral resolution (δλ ≈ 2-4 Å) at blue wavelengths to narrow down their spectral types. We determine these to a precision estimated to be ±1 subtype and then we measure reddenings via spectral energy distribution fitting with reference to appropriate model atmospheres. Corrections for contribution to colour excess from circumstellar discs are made using an established scaling to Ha emission equivalent width. Spectroscopic parallaxes are obtained after luminosity class has been constrained via estimates of distances to neighbouring A/F stars with similar reddenings. Overwhelmingly, the stars in the sample are confirmed as luminous classical Be stars at heliocentric distances ranging from 2 kpc up to ~12 kpc. However, the errors are presently too large to enable the cumulative distribution function with respect to distance to distinguish between models placing the stars exclusively in spiral arms, or in a smooth exponentially declining distribution.Peer reviewe

Organic Pollutants, Heavy Metals and Toxicity in Oil Spill impacted Salt Marsh Sediment Cores, Staten Island, New York City, USA

Sediment cores from Staten Island's salt marsh contain multiple historical oil spill events that impact ecological health. Microtox solid phase bioassay indicated moderate to high toxicity. Multiple spikes of TPH (6524 to 9586 mg/kg) and Σ16 PAH (15.5 to 18.9 mg/kg) were co-incident with known oil spills. A high TPH background of 400–700 mg/kg was attributed to diffuse sources. Depth-profiled metals Cu (1243 mg/kg), Zn (1814 mg/kg), Pb (1140 mg/kg), Ni (109 mg/kg), Hg (7 mg/kg), Cd 15 (mg/kg) exceeded sediment quality guidelines confirming adverse biological effects. Changes in Pb206/207 suggested three metal contaminant sources and diatom assemblages responded to two contamination events. Organic and metal contamination in Saw Mill Creek Marsh may harm sensitive biota, we recommend caution in the management of the 20–50 cm sediment interval because disturbance could lead to remobilisation of pre-existing legacy contamination into the waterway

Potential Environmental Impacts of CO2 Leakage from the Study of Natural Analogue Sites in Europe

AbstractSites of natural CO2 leakage provide opportunities to study the potential environmental impacts of such leakage on near-surface ecosystems. As part of the FP7 RISCS (Research into Impacts and Safety in CO2 Storage) project a geochemical, botanical and microbiological study have been conducted on a natural CO2 vent in Florina, Greece and the findings are compared with the results drawn from Latera, Italy and Laacher See, Germany. Plant and microbial communities appear to have adapted to long-term CO2 exposure. Therefore the findings may not be representative of the effects of potential leakage from man made storage sites

Baseline variability in onshore near surface gases and implications for monitoring at CO2 storage sites

The measurement of gas concentrations and fluxes in the soil and atmosphere is a powerful tool for monitoring geological carbon capture and storage (CCS) sites because the analyses are made directly in the biosphere in which we live. These methods can be used to both find and accurately quantifying leaks, and are visible and tangible data for public and ecosystem safety. To be most reliable and accurate, however, the measurements must be interpreted in the context of natural variations in gas concentration and flux. Such baseline data vary both spatially and temporally due to natural processes, and a clear understanding of their values and distributions is critical for interpreting near-surface gas monitoring techniques. The best example is CO2 itself, as the production of this gas via soil respiration can create a wide range of concentrations and fluxes that must be separated from, and not confused with, CO2 that may leak towards the surface from a storage reservoir. The present article summarizes baseline studies performed by the authors at various sites having different climates and geological settings from both Europe and North America, with focus given to the range of values that can result from near surface processes and how different techniques or data processing approaches can be used to help distinguish a leakage signal from an anomalous, shallow biogenic signal

The impact of boundary layer height on air pollution concentrations in London – early results from the ClearfLo project.

The ClearfLo projects aims to understand the processes generating pollutants like ozone, NOx and particulate matter and their interaction with the urban atmospheric boundary layer. ClearfLo (www.clearflo.ac.uk) is a large multi-institution NERC-funded project that is establishing integrated measurements of the meteorology, composition and particulate loading of London’s urban atmosphere, complemented by an ambitious modeling programme. The project established a new long-term measurement infrastructure in London encompassing measurement capabilities at street level and at elevated sites. These measurements were accompanied by high resolution mod- eling with the UK Met Office Unified model and WRF. This combined measuring/modelling approach enables us to identify the seasonal cycle in the meteorology and composition, together with the controlling processes. Two intensive observation periods in January/February 2012 and during the Olympics in summer 2012 measured London’s atmosphere with higher level of detail. Data from these IOPs will enable us (i) to determine the vertical structure and evolution of the urban atmosphere (ii) to determine the chemical controls on ozone production, particularly the role of biogenic emissions and (iii) to determine the processes controlling the evolution of the size,distribution and composition of particulate matter. We present results from the wintertime IOP in London focusing on a wintertime pollution episode during January 2012. We compare measured concentrations from top of BT Tower in central London with rural background measurements and determine the processes leading to the urban increment in pollutant concentrations. Therefore, we combine high-resolution simulations with the Met Office Unified Model for London and mixing layer heights derived from lidar measurements with air quality measurements in central London in order to quantify the role the boundary layer depth plays for London’s concentrations

A complex systems model of breast cancer etiology: The Paradigm II Model

BACKGROUND: Complex systems models of breast cancer have previously focused on prediction of prognosis and clinical events for individual women. There is a need for understanding breast cancer at the population level for public health decision-making, for identifying gaps in epidemiologic knowledge and for the education of the public as to the complexity of this most common of cancers. METHODS AND FINDINGS: We developed an agent-based model of breast cancer for the women of the state of California using data from the U.S. Census, the California Health Interview Survey, the California Cancer Registry, the National Health and Nutrition Examination Survey and the literature. The model was implemented in the Julia programming language and R computing environment. The Paradigm II model development followed a transdisciplinary process with expertise from multiple relevant disciplinary experts from genetics to epidemiology and sociology with the goal of exploring both upstream determinants at the population level and pathophysiologic etiologic factors at the biologic level. The resulting model reproduces in a reasonable manner the overall age-specific incidence curve for the years 2008-2012 and incidence and relative risks due to specific risk factors such as BRCA1, polygenic risk, alcohol consumption, hormone therapy, breastfeeding, oral contraceptive use and scenarios for environmental toxin exposures. CONCLUSIONS: The Paradigm II model illustrates the role of multiple etiologic factors in breast cancer from domains of biology, behavior and the environment. The value of the model is in providing a virtual laboratory to evaluate a wide range of potential interventions into the social, environmental and behavioral determinants of breast cancer at the population level. Copyright: This is an open access article, free of all copyright, and may be freely reproduced, distributed, transmitted, modified, built upon, or otherwise used by anyone for any lawful purpose

Search for direct production of charginos and neutralinos in events with three leptons and missing transverse momentum in √s = 7 TeV pp collisions with the ATLAS detector

A search for the direct production of charginos and neutralinos in final states with three electrons or muons and missing transverse momentum is presented. The analysis is based on 4.7 fb−1 of proton–proton collision data delivered by the Large Hadron Collider and recorded with the ATLAS detector. Observations are consistent with Standard Model expectations in three signal regions that are either depleted or enriched in Z-boson decays. Upper limits at 95% confidence level are set in R-parity conserving phenomenological minimal supersymmetric models and in simplified models, significantly extending previous results

Jet size dependence of single jet suppression in lead-lead collisions at sqrt(s(NN)) = 2.76 TeV with the ATLAS detector at the LHC

Measurements of inclusive jet suppression in heavy ion collisions at the LHC provide direct sensitivity to the physics of jet quenching. In a sample of lead-lead collisions at sqrt(s) = 2.76 TeV corresponding to an integrated luminosity of approximately 7 inverse microbarns, ATLAS has measured jets with a calorimeter over the pseudorapidity interval |eta| < 2.1 and over the transverse momentum range 38 < pT < 210 GeV. Jets were reconstructed using the anti-kt algorithm with values for the distance parameter that determines the nominal jet radius of R = 0.2, 0.3, 0.4 and 0.5. The centrality dependence of the jet yield is characterized by the jet "central-to-peripheral ratio," Rcp. Jet production is found to be suppressed by approximately a factor of two in the 10% most central collisions relative to peripheral collisions. Rcp varies smoothly with centrality as characterized by the number of participating nucleons. The observed suppression is only weakly dependent on jet radius and transverse momentum. These results provide the first direct measurement of inclusive jet suppression in heavy ion collisions and complement previous measurements of dijet transverse energy imbalance at the LHC.Comment: 15 pages plus author list (30 pages total), 8 figures, 2 tables, submitted to Physics Letters B. All figures including auxiliary figures are available at http://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/HION-2011-02

Measurement of the polarisation of W bosons produced with large transverse momentum in pp collisions at sqrt(s) = 7 TeV with the ATLAS experiment

This paper describes an analysis of the angular distribution of W->enu and W->munu decays, using data from pp collisions at sqrt(s) = 7 TeV recorded with the ATLAS detector at the LHC in 2010, corresponding to an integrated luminosity of about 35 pb^-1. Using the decay lepton transverse momentum and the missing transverse energy, the W decay angular distribution projected onto the transverse plane is obtained and analysed in terms of helicity fractions f0, fL and fR over two ranges of W transverse momentum (ptw): 35 < ptw < 50 GeV and ptw > 50 GeV. Good agreement is found with theoretical predictions. For ptw > 50 GeV, the values of f0 and fL-fR, averaged over charge and lepton flavour, are measured to be : f0 = 0.127 +/- 0.030 +/- 0.108 and fL-fR = 0.252 +/- 0.017 +/- 0.030, where the first uncertainties are statistical, and the second include all systematic effects.Comment: 19 pages plus author list (34 pages total), 9 figures, 11 tables, revised author list, matches European Journal of Physics C versio