In August and September of 2010, measurements of turbulent fluxes and turbulent kinetic energy were made on highways in the Toronto area (Ontario, Canada). In situ turbulence measurements were made with a mobile laboratory while driving on the highway with traffic. Results demonstrate that the turbulent kinetic energy (TKE) spectrum is significantly enhanced on and near the highway by traffic for frequencies above 0.015 Hz. The decay of TKE with distance behind vehicles is well approximated by power-law curves. The strongest increase in TKE is seen while following heavy-duty trucks, primarily for frequencies above 0.7 Hz. From these results, a parameterization of on-road TKE enhancement is developed that is based on vehicle type and traffic-flow rate. TKE with distance downwind of the highway also decays following a power law. The enhancement of roadside TKE is shown to be strongly dependent on traffic flow. The effect of vehicle-induced turbulence on vertical mixing was studied by comparing parameterized TKE enhancement with the typical TKE predictions from the Global Environmental Multiscale weather forecast to predict the potential increase in vertical diffusion that results from highway traffic. It is demonstrated that this increase in TKE by traffic may be locally significant, especially in the early morning.
Reliable characterization of particles freshly emitted from the ocean surface requires a sampling method that is able to isolate those particles and prevent them from interacting with ambient gases and particles. Here we report measurements of particles directly emitted from the ocean using a newly developed in situ particle generator (Sea Sweep). The Sea Sweep was deployed alongside R/V Atlantis off the coast of California during May of 2010. Bubbles were generated 0.75 m below the ocean surface with stainless steel frits and swept into a hood/vacuum hose to feed a suite of aerosol instrumentation on board the ship. The number size distribution of the directly emitted, nascent particles had a dominant mode at 55-60 nm (dry diameter) and secondary modes at 30-40 nm and 200-300 nm. The nascent aerosol was not volatile at 230 degrees C and was not enriched in SO4=, Ca++, K+, or Mg++ above that found in surface seawater. The organic component of the nascent aerosol (7% of the dry submicrometer mass) volatilized at a temperature between 230 and 600 degrees C. The submicrometer organic aerosol characterized by mass spectrometry was dominated by non-oxygenated hydrocarbons. The nascent aerosol at 50, 100, and 145 nm dry diameter behaved hygroscopically like an internal mixture of sea salt with a small organic component. The CCN/CN activation ratio for 60 nm Sea Sweep particles was near 1 for all supersaturations of 0.3 and higher indicating that all of the particles took up water and grew to cloud drop size. The nascent organic aerosol mass fraction did not increase in regions of higher surface seawater chlorophyll but did show a positive correlation with seawater dimethylsulfide (DMS).
OBJECTIVES: This study was to explore the independent influence of menopause on cardiovascular disease (CVD) and its risk factors in rural Chinese females. STUDY DESIGN: This cross-sectional population-based study enrolled 2245 premenopausal and 2498 postmenopausal women aged 40-59 years in Fangshan district, Beijing, China. Data was collected by face-to-face interview, physical examination and biochemical examination during 2009 and 2010. General liner models were employed to calculate age-adjusted means of cardiovascular risk factors (CRFs). The comparisons of CVD and it risk factors according to menopausal status, and calculation of adjusted odds ratios/coefficients and their 95% confidence intervals for the associations of quartiles of elapsed time since menopause and age at menopause with CVD and its risk factors was performed by multivariate logistic/liner regression models separately. RESULTS: After adjustment for age and other confounders, no statistically significant association of menopause with CVD was observed in our participants; however, dyslipidemia prevalence and levels of waist-to-hip ratio, triglycerides, total cholesterol and low-density lipoprotein cholesterol were presented higher in postmenopausal group, compared to the premenopausal one (P<0.05). Compared to women who had been menopausal for less than1 year, those with the elapsed time since menopause of 2-3 years had higher CHD prevalence, higher triglycerides level and lower high-density lipoprotein cholesterol level (P<0.05). CONCLUSIONS: Postmenopausal women in rural China had worse CRFs profile than the premenopausal ones, which implied menopause might aggravate the CRFs epidemic beyond effects of aging, and would increase the CVD burden during and after their middle ages.
The propagation speed Vc of the streamwise velocity fluctuations u' in turbulent channel flows is calculated using direct numerical simulation (DNS) data at four Mach numbers (M=0, 0.8, 2.0, and 3.0). The profiles of Vc are shown to display remarkable similarity at different M. Quantitative models are developed based on a statistical structure called Velocity-Vorticity Correlation Structure (VVCS), defined as the vorticity region most correlated to velocity fluctuations at a fixed location. Good agreement with DNS-measured propagation velocities is obtained throughout the channel and for all M. The result confirms earlier speculation that the near-wall propagation is due to an advection by coherent vortex structures, and validates the concept of the VVCS.