The hygroscopic growth factor (HGF) and cloud condensation nuclei (CCN) activity are measured for surrogates that mimic atmospherically relevant oligomers, including glyoxal trimer dihydrate, methyl glyoxal trimer dihydrate, sucrose, methyl glyoxal mixtures with sulfuric acid and glycolic acid, and 2,4-hexandienal mixtures with sulfuric acid and glycolic acid. For the single-component aerosols, the measured HGF ranges from 1.3 to 1.4 at a relative humidity of 90%, and the hygroscopicity parameter (kappa) is in the range of 0.06 to 0.19 on the basis of the measured CCN activity and 0.13 to 0.22 on the basis of the measured HGF, compared to the calculated values of 0.08 to 0.16. Large differences exist in the. values derived using the measured HGF and CCN data for the multi-component aerosols. Our results reveal that, in contrast to the oxidation process, oligomerization decreases particle hygroscopicity and CCN activity and provides guidance for analyzing the organic species in ambient aerosols.
BACKGROUND: Urbanizing rural areas in China face a rapidly growing cardiovascular disease burden. Epidemiologic studies and effective preventive strategies are urgently needed. METHODS: The Fangshan Cohort Study is a prospective study that began in 2008 and targets local residents aged 40 years or older living in 3 towns in the Fangshan district of Beijing. The baseline examination included a questionnaire on medical history, health knowledge, and behaviors related to cardiovascular disease, as well as physical and blood biochemical examinations. The questionnaire survey will be readministered every 2 years. A system for surveillance of mortality and morbidity of cardiovascular disease is under development. RESULTS: A total of 20 115 adults (6710 men and 13 405 women) were investigated at baseline (participation rate = 84.5%). The data indicate that overweight/obesity is a serious public health issue in Fangshan: average body mass index was 25.4 kg/m(2) among men and 26.5 kg/m(2) among women, and the prevalences of overweight and obesity were 43.6% and 10.3% among men and 47.0% and 17.7% among women. CONCLUSIONS: The Fangshan Cohort Study will provide data on cardiovascular risk factors and disease profile, which will assist in developing appropriate prevention and control strategies for cardiovascular disease in rural Chinese communities.
Streams play an important role in linking the land with lakes. Nutrients released from agricultural or urban sources flow via streams to lakes, causing water quality deterioration and eutrophication. Therefore, accurate simulation of streamflow is helpful for water quality improvement in lake basins. Lake Dianchi has been listed in the Three Important Lakes Restoration Act' in China, and the degradation of its water quality has been of great concern since the 1980s. To assist environmental decision making, it is important to assess and predict hydrological processes at the basin scale. This study evaluated the performance of the soil and water assessment tool (SWAT) and the feasibility of using this model as a decision support tool for predicting streamflow in the Lake Dianchi Basin. The model was calibrated and validated using monthly observed streamflow values at three flow stations within the Lake Dianchi Basin through application of the sequential uncertainty fitting algorithm (SUFI-2). The results of the autocalibration method for calibrating and the prediction uncertainty from different sources were also examined. Together, the p-factor (the percentage of measured data bracketed by 95% prediction of uncertainty, or 95PPU) and the r-factor (the average thickness of the 95PPU band divided by the standard deviation of the measured data) indicated the strength of the calibration and uncertainty analysis. The results showed that the SUFI-2 algorithm performed better than the autocalibration method. Comparison of the SUFI-2 algorithm and autocalibration results showed that some snowmelt factors were sensitive to model output upstream at the Panlongjiang flow station. The 95PPU captured more than 70% of the observed streamflow at the three flow stations. The corresponding p-factors and r-factors suggested that some flow stations had relatively large uncertainty, especially in the prediction of some peak flows. Although uncertainty existed, statistical criteria including R-2 and Nash-Sutcliffe efficiency were reasonably determined. The model produced a useful result and can be used for further applications. Copyright (c) 2012 John Wiley & Sons, Ltd.
To ensure application interoperability in visual object search technologies, the MPEG Working Group has made great efforts in standardizing visual search technologies. Moreover, extraction and transmission of compact descriptors are valuable for next-generation, mobile, visual search applications. This article reviews the significant progress of MPEG Compact Descriptors for Visual Search (CDVS) in standardizing technologies that will enable efficient and interoperable design of visual search applications. In addition, the article presents the location search and recognition oriented data collection and benchmark under the MPEG CDVS evaluation framework.
To investigate the secondary organic aerosol (SOA) formation in Beijing, fine particle (PM2.5) samples were collected at an urban site (Peking University, PKU) and a rural site (Yufa) during CAREBEITING 2008 summer intensive field campaign. Several approaches were used to estimate SOA concentrations, including tracer-yield method, non-primary organic carbon method (receptor model, Chemical Mass Balance model), non-biomass burning water soluble organic carbon (WSOC) method and EC tracer OC/EC ratio method. To develop non-biomass burning WSOC method, simulation of typical Chinese biomass burning was conducted to obtain the important parameters. The average WSOC/OC ratio in Chinese biomass burning is 0.48 +/- 0.04. This ratio can be used in non-biomass burning WSOC method to estimate SOC of China. The results from different methods all indicated secondary formation has become major contributor to organic aerosols in Beijing, accounting for 50% or more of the total OC. A closure study was made by combination of CMB model and tracer-yield method. Five primary sources, including vegetative detritus, biomass burning, coal burning, gasoline engines and diesel engines, and four secondary organic aerosols derived from isoprene, alpha-pinene, beta-caryophyllene and toluene were apportioned. To the current knowledge, about 20%similar to 27% of the OC sources still remain unknown. Applicability of these SOC methods in China was tested by comparing the different methods. Tracer-yield method, CMB model and EC tracer OC/EC ratio method can be used to estimate SOC in China. However, non-biomass burning WSOC method can only be used to estimate water-soluble SOC. Uncertainty analysis was conducted to help researchers to determine the proper method to estimate SOC in China. Tracer-yield method underestimates total SOC, because it can only estimate SOCs from several precursors. Similarly, non-biomass burning WSOC method also underestimate SOC. Non-primary OC method overestimates SOC due to unapportioned primary OC, especially in urban area where the particle sources are complicated. The uncertainty of EC-tracer OC/EC ratio method is mainly from the primary OC/EC ratio. The largest overestimation and underestimation of single point value can be 54% and 64%.
To investigate the secondary organic aerosol (SOA) formation in Beijing, fine particle (PM2.5) samples were collected at an urban site (Peking University, PKU) and a rural site (Yufa) during CAREBEITING 2008 summer intensive field campaign. Several approaches were used to estimate SOA concentrations, including tracer-yield method, non-primary organic carbon method (receptor model, Chemical Mass Balance model), non-biomass burning water soluble organic carbon (WSOC) method and EC tracer OC/EC ratio method. To develop non-biomass burning WSOC method, simulation of typical Chinese biomass burning was conducted to obtain the important parameters. The average WSOC/OC ratio in Chinese biomass burning is 0.48 +/- 0.04. This ratio can be used in non-biomass burning WSOC method to estimate SOC of China. The results from different methods all indicated secondary formation has become major contributor to organic aerosols in Beijing, accounting for 50% or more of the total OC. A closure study was made by combination of CMB model and tracer-yield method. Five primary sources, including vegetative detritus, biomass burning, coal burning, gasoline engines and diesel engines, and four secondary organic aerosols derived from isoprene, alpha-pinene, beta-caryophyllene and toluene were apportioned. To the current knowledge, about 20%similar to 27% of the OC sources still remain unknown. Applicability of these SOC methods in China was tested by comparing the different methods. Tracer-yield method, CMB model and EC tracer OC/EC ratio method can be used to estimate SOC in China. However, non-biomass burning WSOC method can only be used to estimate water-soluble SOC. Uncertainty analysis was conducted to help researchers to determine the proper method to estimate SOC in China. Tracer-yield method underestimates total SOC, because it can only estimate SOCs from several precursors. Similarly, non-biomass burning WSOC method also underestimate SOC. Non-primary OC method overestimates SOC due to unapportioned primary OC, especially in urban area where the particle sources are complicated. The uncertainty of EC-tracer OC/EC ratio method is mainly from the primary OC/EC ratio. The largest overestimation and underestimation of single point value can be 54% and 64%.
Using a quasi-experimental opportunity offered by greatly restricted air pollution emissions during the Beijing Olympics compared to before and after the Olympics, we conducted the current study to compare ultrafine particles (UFPs) and fine particles (PM2.5) in their associations with biomarkers reflecting multiple pathophysiological pathways linking exposure and cardiorespiratory events. Number concentrations of particles (13.0-764.7 nm) and mass concentrations of PM2.5 were measured at two locations within 9 km from the residence and workplace of 125 participating Beijing residents. Each participant was measured 6 times for biomarkers of autonomic function (heart rate, systolic and diastolic blood pressures), hemostasis (von Willebrand factor, soluble CD40 ligand, and P-selectin), pulmonary inflammation and oxidative stress (exhaled nitric oxide and exhaled breath condensate pH, malondialdehyde, and nitrite), and systemic inflammation and oxidative stress (urinary malondialdehyde and 8-hydroxy-2'-deoxyguanosine, plasma fibrinogen, and white blood cells). Linear mixed models were used to estimate associations of biomarkers with UFPs and PM2.5 measured 1-7 days prior to biomarker measurements (lags). We found that the correlation coefficient for UFPs at two locations ( approximately 9 km apart) was 0.45, and at the same location, the correlation coefficient for PM2.5 vs UFPs was -0.18. Changes in biomarker levels associated with increases in UFPs and PM2.5 were comparable in magnitude. However, associations of certain biomarkers with UFPs had different lag patterns compared to those with PM2.5, suggesting that the ultrafine size fraction (
Content-based copy detection (CBCD) is drawing increasing attention as an alternative technology to watermarking for video identification and copyright protection. In this article, we present a comprehensive method to detect copies that are subjected to complicated transformations. A multimodal feature representation scheme is designed to exploit the complementarity of audio features, global and local visual features so that optimal overall robustness to a wide range of complicated modifications can be achieved. Meanwhile, a temporal pyramid matching algorithm is proposed to assemble frame-level similarity search results into sequence-level matching results through similarity evaluation over multiple temporal granularities. Additionally, inverted indexing and locality sensitive hashing (LSH) are also adopted to speed up similarity search. Experimental results over benchmarking datasets of TRECVID 2010 and 2009 demonstrate that the proposed method outperforms other methods for most transformations in terms of copy detection accuracy. The evaluation results also suggest that our method can achieve competitive copy localization preciseness.