The Geographic Disparities in Transportation-Related Physical Activity in the United States: An Analysis of the 2017 NHTS Data

Research on the relationship between urbanicity and physical activity yielded mixed results despite many studies consistently showing that residents tended to undertake more transportation-related physical activity in a more urban environment. This study analyzed the 2017 NHTS data to examine the geographic disparities in physical activity, particularly transportation-related physical activity in the United States. Our analysis suggests the relationship between urbanicity and physical activity demonstrates a flat U-shape in graphed data. Residents are more physically active when they live in the areas from the two ends of the urbanization spectrum: inner cities and inner suburbs of large metropolitan areas and the rural parts of non-metropolitan areas. Suburbanites, particularly mid-ring and outer-ring suburbanites walk the least. Only very slight geographic variation exists in the weekly rates of walk and bike trips that are strictly for exercise. The study revealed greater variation of the weekly rates of walk and bike trips that are for non-exercise purposes. This study suggests a more complicated relationship between urbanicity, active travel, and physical activity in a broader geographic context. More research needs to examine whether and how new urbanist design can promote active travel, particularly active travel strictly for exercise, in rural areas and areas of low urbanicity

Can Californian Households Save Money on Transportation Costs by Living in Transit-Oriented Developments (TODs)?

Many residents in large Californian metropolitan areas are heavily burdened by housing costs. Advocates, researchers, and elected officials in California are debating whether transit-oriented development (TOD) could be an effective tool to mitigate the housing affordability problem by increasing housing supply and reducing transportation costs in transit-rich neighborhoods. This study contributes to this debate by estimating how much Californian families can save on transportation costs by living in transit-oriented developments (TODs). By utilizing the confidential version of the 2010–2012 California Household Travel Survey, this study evaluates the impact of TOD on household transportation expenditures by comparing TOD households with two control groups. When controlling for household demographics, TOD households save $1,232 per year on transportation expenditures—18$429 per year—about 6% of their total annual transportation expenditures. The study confirms that Californian households save money on transportation costs by living in TODs mainly because they own fewer vehicles. About two-thirds of the savings can be attributed to transit-friendly neighborhood environment and one-third to access to rail transit, which highlights the importance of integrating a rail transit system with supportive land use planning and neighborhood design

Smart Transportation in Small- and Medium-sized Cities in Central California

The research on smart transportation in the United States has centered on large metropolitan areas. The adoption of smart transportation technologies in small-and medium-sized cities outside of large metropolitan areas is less studied and understood. This study examined the adoption of smart transportation technologies in small-and medium-sized cities in Central California. The analysis was based on the online survey responses from 29 transportation officials and professionals who worked for 18 municipal government departments and six metropolitan planning organizations (MPOs) in Central California as well as in depth semi-structured interviews with seven of them. The study showed that smart transportation in small-and medium-sized cities was mainly car-centric. Slightly more than half of the survey respondents were either unsure or suspicious about the usefulness of smart transportation technologies in addressing local transportation problems. The study revealed several barriers to the adoption of smart transportation technologies in small- and medium-sized cities including insufficient funding, limited staff capacity, a lack of coordination among small cities within a region, small population sizes, and low-density of development. The interviews suggested that some of these barriers, particularly the funding issue, were more complicated than they first appeared. We offer four major policy recommendations based on the findings from this study

Performance Evaluation of Manure Nitrogen Output Models Suitable for Lactating Dairy Cows in China

Manure nitrogen (N) output from dairy cattle is a major environmental concern in China. Various empirical models are available to predict manure N output from dairy cattle, but accuracy and precision of these models has not been assessed for Chinese conditions. The objective of this study was to evaluate the performance of extant models that predict different forms of manure N output for lactating dairy cows in China with the aim of identifying the best-fit and most suitable prediction models. A total of 35 empirical models were evaluated for their ability to predict N excretion of dairy cows in China fed a wide range of diets. The data set consisted of 99 treatment means from 32 publications with information on animal and dietary characteristics and N output flows. Performance of models was evaluated using root mean square prediction error (RMSPE) and concordance correlation coefficient (CCC) analysis. The N intake (NI) based model of Kebreab et al. (2010) was selected as best for predicting fecal N excretion (RMSPE = 15.8% and CCC = 0.75). The Reed et al. (2015) model, which also used NI as an input variable, was most suitable for predicting urinary N (RMSPE = 26.0% and CCC = 0.63) and total N (RMSPE = 15.8% and CCC = 0.81). Models predicting urinary urea N (UUN) and urinary N / total N performed poorly. Overall, the deviation of regression line from the equality line (y = x line) for even the best-fit urinary, fecal, and total N excretion models demonstrated the need to develop improved models for use under Chinese conditions. Using N output data from dairy cows in China to develop manure N output models may help improve environmental stewardship of the dairy industry in China

Ammonia and greenhouse gas emissions from co-composting of dead hens with manure as affected by forced aeration rate

The effect of ventilation rate (VR) on ammonia (NH3) and greenhouse gas (GHG) emissions from composting piles of dead hens mixed with hen manure was quantified by measuring the gaseous concentrations and airflow rate through the compost bins. Three VR levels of 0.9, 0.7 and 0.5 m³/hr/bin (equivalent to the air exchanges per hour of 0.9, 0.7 and 0.5) were evaluated, each with three replicates. The compost piles were turned once (on day 58) during the 11-wk composting period. Gaseous concentrations of the inlet and exhaust air of the compost bins were measured using a multi-gas infrared photoacoustic analyzer coupled with a multi-channel sampler; VR was measured with a flow meter; and the emission rate (ER) of each gas was computed from the VR and the gas concentration. Decomposition of the carcass over the 11-wk composting period was found to be greater than 88%, as assessed by the reduction in carcass mass. NH3 ER was relatively stable when the compost pile was at high temperatures (~60?). Sharp increase in carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) emissions occurred quickly after construction of the compost pile. VR was found to significantly affect NH3, CO2 and CH4 emissions (p less than 0.05). Specifically, cumulative emissions per kg of initial co-compost matter for the three VR of 0.9, 0.7 and 0.5 m³/hr/bin were, respectively, 2.4, 2.0 and 1.2 g NH3; 78, 66 and 42 g CO2; 120, 90 and 52 mg CH4; and 6.4, 6.1 and 5.1 mg N2O. Hence, the study results suggest that the rate of forced aeration can be adjusted to reduce NH3 and GHG emissions from animal mortality compositing

Assessment of Tubing Type on Ammonia Gas Adsorption

Different types of tubing and operating conditions may be involved when measuring ammonia (NH3) concentrations and its emissions from animal production facilities. Prices of commercially available tubing vary substantially. A question that has often come up but has not been well investigated is how the tubing type (e.g., PVC vs. FEP) may impact the certainty of NH3 concentration measurement. The study reported here was conducted to address this issue in that it assessed and compared the magnitude of NH3 adsorption to different types of commercially available tubing under conditions that may be present in animal feeding operation (AFO) air emission studies. The types of tubing evaluated were: Teflon® (PFA and FEP tubing), HDPE (clear plastic tubing), and PVC (vinyl tubing). Each tested tubing had a length of 30.5 m (100 ft) and an inside diameter of 6.35 mm (0.25 in.). Five nominal NH3 levels of 10, 20, 40, 80, and 160 ppm, generated with poultry manure, were passed through the tested tubing at an airflow rate of 8 L min-1 (0.28 CFM) for 60 min. Simultaneous measurements of NH3 concentrations at the inlet and outlet of the tested tubing were made with two photoacoustic gas spectrometers (1% repeatability of measured value and 0.2-ppm NH3 detection limit). Although the Teflon tubing had significantly lower NH3 adsorption than the HDPE or PVC tubing, all the tested tubing showed \u3c3% NH3 differences between the inlet and outlet concentrations after the 60-min exposure and mostly \u3c1% for NH3 levels \u3e40 ppm. The results of this study thus suggest that the HDPE and PVC tubing offer viable, more economical air sampling options for AFO NH3 emission studies

Evaluation of Airborne Dust Concentration And Effectiveness of Cooling fan with Spraying Misting Systems in Swine Gestation Houses

Airborne dust in swine houses can cause serious health problems for humans as well as for animals. The aim of this experiment was to evaluate the airborne dust concentration range and effectiveness of cooling fan with spraying misting systems in the gestation houses in the management practices of China. The experiment was implemented in a gestation barn housed 239 gestation pigs in Hebei Province of China. The tests showed that the average airborne dust concentration was about 4.70 ±3.24 mg/m3 in cold weather and 2.18 ±1.61 mg/m3 in warm weather, respectively. The high dust concentration of 17.55 ± 1.18 mg/ m3 in winter and 15.25 ± 1.77 mg/m3 in summer happened in the feeding period. When the misting cooling system with droplet diameter of 20-50µ m turned on, the average airborne dust concentration could be reduced by 75%, from 7.94 ±4.67 mg/m3 to 1.98 ±1.80 mg/m3, during the feeding period

Daily Variation of Thyroid Hormones in Broiler Under High-Temperature Conditions

Market-size (61-68 day-old) AA broiler chickens were exposed to simulated high-cyclic summer temperatures of North, Central and South China for 5 continuous days. Blood samples were collected at 0AM, 4AM, 8AM, 0PM, 4PM and 8PM each day, and concentrations of triiodothyronine (T3) and thyroxine (T4) were determined by double-antibody radioimmunoassay (RIA). T3, T4 concentration and T3/T4 ratio had two peaks, but the daily variation patterns of thyroid hormones were different between each other. T3 peaked at 12 AM and 12 PM, while T4 peaked at 8 AM and 12 PM, with the two peaks of T3/T4 ratio showing at 4 AM and 12 AM. The lowest concentrations of both T3 and T4 occurred at 4 PM. According to above results, the blood samples should be collected around the time corresponding to the peak of temperature sinusoid, when thyroid hormones (both T3 and T4 concentrations) are used to evaluate the heat stress status of broilers