263 research outputs found
A Modeling Investigation of Human Exposure to Select Traffic-Related Air Pollutants in the Tampa Area: Spatiotemporal Distributions of Concentrations, Social Distributions of Exposures, and Impacts of Urban Design on Both
No full textIncreasing vehicle dependence in the United States has resulted in substantial emissions of traffic-related air pollutants that contribute to the deterioration of urban air quality. Exposure to urban air pollutants trigger a number of public health concerns, including the potential of inequality of exposures and health effects among population subgroups. To better understand the impact of traffic-related pollutants on air quality, exposure, and exposure inequality, modeling methods that can appropriately characterize the spatiotemporally resolved concentration distributions of traffic-related pollutants need to be improved. These modeling methods can then be used to investigate the impacts of urban design and transportation management choices on air quality, pollution exposures, and related inequality.
This work will address these needs with three objectives: 1) to improve modeling methods for investigating interactions between city and transportation design choices and air pollution exposures, 2) to characterize current exposures and the social distribution of exposures to traffic-related air pollutants for the case study area of Hillsborough County, Florida, and 3) to determine expected impacts of urban design and transportation management choices on air quality, air pollution exposures, and exposure inequality.
To achieve these objectives, the impacts of a small-scale transportation management project, specifically the \u2795 Express\u27 high occupancy toll lane project, on pollutant emissions and nearby air quality was investigated. Next, a modeling method capable of characterizing spatiotemporally resolved pollutant emissions, concentrations, and exposures was developed and applied to estimate the impact of traffic-related pollutants on exposure and exposure inequalities among several population subgroups in Hillsborough County, Florida. Finally, using these results as baseline, the impacts of sprawl and compact urban forms, as well as vehicle fleet electrification, on air quality, pollution exposure, and exposure inequality were explored.
Major findings include slightly higher pollutant emissions, with the exception of hydrocarbons, due to the managed lane project. Results also show that ambient concentration contributions from on-road mobile sources are disproportionate to their emissions. Additionally, processes not captured by the CALPUFF model, such as atmospheric formation, contribute substantially to ambient concentration levels of the secondary pollutants such as acetaldehyde and formaldehyde. Exposure inequalities for NOx, 1,3-butadiene, and benzene air pollution were found for black, Hispanic, and low income (annual household income less than $20,000) subgroups at both short-term and long-term temporal scales, which is consistent with previous findings. Exposure disparities among the subgroups are complex, and sometimes reversed for acetaldehyde and formaldehyde, due primarily to their distinct concentration distributions. Compact urban form was found to result in lower average NOx and benzene concentrations, but higher exposure for all pollutants except for NOx when compared to sprawl urban form. Evidence suggests that exposure inequalities differ between sprawl and compact urban forms, and also differ by pollutants, but are generally consistent at both short and long-term temporal scales. In addition, vehicle fleet electrification was found to result in generally lower average pollutant concentrations and exposures, except for NOx. However, the elimination of on-road mobile source emissions does not substantially reduce exposure inequality.
Results and findings from this work can be applied to assist transportation infrastructure and urban planning. In addition, method developed here can be applied elsewhere for better characterization of air pollution concentrations, exposure and related inequalities
Impacts of Compact Growth and Electric Vehicles on Future Air Quality and Urban Exposures may be Mixed
No full text‘Smart’ growth and electric vehicles are potential solutions to the negative impacts of worldwide urbanization on air pollution and health. However, the effects of planning strategies on distinct types of pollutants, and on human exposures, remain understudied. The goal of this work was to investigate the potential impacts of alternative urban designs for the area around Tampa, Florida USA, on emissions, ambient concentrations, and exposures to oxides of nitrogen (NOx), 1,3-butadiene, and benzene. We studied three potential future scenarios: sprawling growth, compact growth, and 100% vehicle fleet electrification with compact growth. We projected emissions in the seven-county region to 2050 based on One Bay regional visioning plan data. We estimated pollutant concentrations in the county that contains Tampa using the CALPUFF dispersion model. We applied residential population projections to forecast acute (highest hour) and chronic (annual average) exposure. The compact scenario was projected to result in lower regional emissions of all pollutants than sprawl, with differences of − 18%, − 3%, and − 14% for NOx, butadiene, and benzene, respectively. Within Hillsborough County, the compact form also had lower emissions, concentrations, and exposures than sprawl for NOx (− 16%/− 5% for acute/chronic exposures, respectively), but higher exposures for butadiene (+ 41%/+30%) and benzene (+ 21%/+9%). The addition of complete vehicle fleet electrification to the compact scenario mitigated these in-county increases for the latter pollutants, lowering predicted exposures to butadiene (− 25%/− 39%) and benzene (− 5%/− 19%), but also resulted in higher exposures to NOx (+ 81%/+30%) due to increased demand on power plants. These results suggest that compact forms may have mixed impacts on exposures and health. ‘Smart’ urban designs should consider multiple pollutants and the diverse mix of pollutant sources. Cleaner power generation will also likely be needed to support aggressive adoption of electric vehicles
Spatiotemporal Distributions of Ambient Oxides of Nitrogen, with Implications for Exposure Inequality and Urban Design
No full textIntra-urban differences in concentrations of oxides of nitrogen (NOx) and exposure disparities in the Tampa area were investigated across temporal scales through emissions estimation, dispersion modeling, and analysis of residential subpopulation exposures. A hybrid estimation method was applied to provide link-level hourly on-road mobile source emissions. Ambient concentrations in 2002 at 1 km resolution were estimated using the CALPUFF dispersion model. Results were combined with residential demographic data at the block-group level, to investigate exposures and inequality for select racioethnic, age, and income population subgroups. Results indicate that on-road mobile sources contributed disproportionately to ground-level concentrations and dominated the spatial footprint across temporal scales (annual average to maximum hour). The black, lower income (less than 60K) subgroups had lower than average exposures. As annual average concentration increased, the disparity between groups generally increased. However, for the highest 1-hr concentrations, reverse disparities were also found
Exposure and inequality for select urban air pollutants in the Tampa Bay area
No full textAbstractAir pollution exposure has been linked to numerous adverse health effects, with some disadvantaged subgroups disproportionately burdened. The objective of this work was to characterize distributions of emissions and concentrations of a few important urban air toxics at high spatiotemporal resolution in order to assess exposure and inequality. Benzene, 1,3-butadiene, formaldehyde, and acetaldehyde were the focus pollutants, with oxides of nitrogen (NOx) estimated for comparisons. Primary pollutant emissions were estimated for the full spectrum of source types in the Tampa area using a hybrid approach that is most detailed for major roadways and includes hourly variations in vehicle speed. Resultant pollutant concentrations were calculated using the CALPUFF dispersion model, and combined with CMAQ model output to account for secondary formation of formaldehyde and acetaldehyde. Census demographic data were applied to estimate residential pollution exposures and inequality among population subgroups. Estimated concentrations of benzene, 1,3-butadiene, and NOx were generally higher in urban areas and lower in rural areas. Exposures to these pollutants were disproportionately high for subgroups characterized as black, Hispanic and low income (annual household income less than $20,000). For formaldehyde and acetaldehyde, the patterns of concentration and exposure were largely reversed. Results suggest that disparities in exposure depend on pollutant type
Axons-on-a-chip for mimicking non-disruptive diffuse axonal injury underlying traumatic brain injury
No full textDiffuse axonal injury (DAI) is the most severe pathological feature of traumatic brain injury (TBI). However, how primary axonal injury is induced by transient mechanical impacts remains unknown, mainly due to the low temporal and spatial resolution of medical imaging approaches. Here we established an axon-on-achip (AoC) model for mimicking DAI and monitoring instant cellular responses. Integrating computational fluid dynamics and microfluidic techniques, DAI was induced by injecting a precisely controlled micro-flux in the transverse direction. The clear correlation between the flow speed of injecting flux and the severity of DAI was elucidated. We next used the AoC to investigate the instant intracellular responses underlying DAI and found that the dynamic formation of focal axonal swellings (FAS) accompanied by Ca2+ surge occurs during the flux. Surprisingly, periodic axonal cytoskeleton disruption also occurs rapidly after the flux. These instant injury responses are spatially restricted to the fluxed axon, not affecting the overall viability of the neuron in the acute stage. Compatible with high-resolution live microscopy, the AoC provides a versatile system to identify early mechanisms underlying DAI, offering a platform for screening effective treatments to alleviate TBI.Xiaorong Pan, Jie Li, Wei Li, Haofei Wang, Nela Durisic, Zhenyu Li, Yu Feng, Yifan Liu, Chun-Xia Zhao and Tong Wan
Using cell phone location to assess misclassification errors in air pollution exposure estimation
No full textAir pollution epidemiologic and health impact studies often rely on home addresses to estimate individual subject\u27s pollution exposure. In this study, we used detailed cell phone location data, the call detail record (CDR), to account for the impact of spatiotemporal subject mobility on estimates of ambient air pollutant exposure. This approach was applied on a sample with 9886 unique simcard IDs in Shenzhen, China, on one mid-week day in October 2013. Hourly ambient concentrations of six chosen pollutants were simulated by the Community Multi-scale Air Quality model fused with observational data, and matched with detailed location data for these IDs. The results were compared with exposure estimates using home addresses to assess potential exposure misclassification errors. We found the misclassifications errors are likely to be substantial when home location alone is applied. The CDR based approach indicates that the home based approach tends to over-estimate exposures for subjects with higher exposure levels and under-estimate exposures for those with lower exposure levels. Our results show that the cell phone location based approach can be used to assess exposure misclassification error and has the potential for improving exposure estimates in air pollution epidemiology studies. Cell phone location-based exposure estimation has the potential for improving exposure estimates vs. home address-based approaches that are likely to have increased misclassification errors because it does not account for individual mobility
Data Analysis and Modeling of Chilled Water Loops in Air Conditioning Systems
No full textArtificial neural network has been widely used in air conditioning systems as an effective method for predicting parameters, and the accuracy of ANN model relies on training data and network structure. In order to increase the quality of chilled water loops model, this paper develops an optimal data processing algorithm combining Kalman filtering with particle swarm optimization to compensate for uncertain factors and disturbances of collected data from the case building and establishes the nonlinear variation trend database. Based on Elman and BP neural networks, this paper proposes the improved network structures to avoid the local optimum predicted value of chilled water loops and increase data training speed. Simulation results show that this algorithm improves the data accuracy of current percentage (CP) of chillers and chilled water temperatures 12% and 9%. Compared with Elman and BP models, mean absolute errors of CP improved models are improved 24.1% and 10.3%, and mean squared errors of water temperature improved models are improved 5.2% and 4.8%. For the purpose of energy conservation control in air conditioning systems, this work has an application value and can be used for predicting other parameters of buildings.</jats:p
InstantOMR: Oblivious Message Retrieval with Low Latency and Optimal Parallelizability
No full textAnonymous messaging systems, such as privacy-preserving blockchains and private messaging applications, need to protect recipient privacy: ensuring no linkage between the recipient and the message. This raises the question: how can untrusted servers assist in delivering the pertinent messages to each recipient, without requiring the recipient to linearly scan all messages or revealing the intended recipient of each message? Oblivious message retrieval (OMR), a recently proposed primitive, addresses this issue by using homomorphic encryption in the single-server setting.
This work introduces , a novel OMR scheme that combines TFHE functional bootstrapping with standard RLWE operations in a hybrid design, achieving significant improvements in both latency and parallelizability compared to prior BFV-based schemes. We propose a two-layer bootstrapping architecture and hybrid use of TFHE and regular RLWE homomorphic operations for . Our implementation, using the - library (and estimates based on -), demonstrates that offers the following key advantages:
- Low latency: achieves lower latency than , the state-of-the-art single-server OMR construction. This translates directly into reduced recipient waiting time (by the same factor) in the streaming setting, where the detector processes incoming messages on-the-fly and returns a digest immediately upon the recipient becoming online.
- Optimal parallelizability: scales near-optimally with available CPU cores (by processing messages independently), so for high core counts, it is faster than SophOMR (whose parallelism is constrained by its reliance on BFV)
Efficient extracellular expression of transpeptidase sortase A in Pichia pastoris
No full textIn order to achieve efficient extracellular expression of Sortase A (SrtA), various strategies in Pichia pastoris system were applied in this study. Among different constructed recombinant strains, the SMD1168 strain integrated 5.7 copies of srtA gene under control of AOX1 promoter was proved to be the best strain for the extracellular SrtA expression. After the optimization of fermentation conditions (induction 72 h at 28 degrees C, initial pH 6.0, supplemented with 1.5% methanol), the highest yield and activity of extracellular SrtA reached 97.8 mg/L and 131.9 U/mL at the shake-flask level, respectively. This is the first report on the efficient secretory expression of SrtA in P. pastoris and the yield of SrtA is the maximum compared with previous reports. In addition, the transpeptidation activity of extracellular SrtA was confirmed by the successful immobilization of enhanced green fluorescent protein (EGFP) onto Gly(3)-polystyrene beads. (C) 2017 Elsevier Inc. All rights reserved.National Natural Science Foundation of China [21472070]; Project for Jiangsu Scientific and Technological Innovation Team; Fund for Jiangsu Distinguished Professorship Program; Jiangsu Postdoctoral Science Foundation [1402070C]; State Key Laboratory of Natural and Biomimetic Drugs [K20140216]; Priority Academic Program Development of Jiangsu Higher Education Institutions; 111 Project [111-2-06]; Jiangsu province "Collaborative Innovation Center for Advanced Industrial Fermentation" industry development programSCI(E)ARTICLE132-13813
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