Trends and patterns in fatal US motorcycle crashes, 2000–2016

Objective: To investigate trends of motorcyclist fatalities and identify at-risk populations by motorcyclist demographics and crash characteristics.

Methods: We used the Fatality Analysis Reporting System (FARS) database (2000–2016) to track fatality rate trends, which were quantified by using Poisson mixed-effects regression models comparing 2000–2001 and 2007–2008, as well as 2009–2010 and 2015–2016.

Results: The overall fatality rate per 100,000 population increased from 2000 to 2016, defined by two trend lines—before and after the economic recession in 2008–2009. The overall fatality rate ratio between 2000–2001 and 2007–2008 was 1.60 [95% Confidence Interval (CI): 1.51–1.70], and between 2009–2010 and 2015–2016 was 1.09 (95% CI: 1.02–1.18). Fatality rates increased among all age groups, particularly for motorcyclists aged 60 and older. Those aged 18–29 had the highest fatality rates overall. Age-and-sex standardized state fatality rates were consistently highest in Wyoming, South Dakota, and South Carolina and lowest in Massachusetts, New York and New Jersey.

Conclusion: Motorcycle fatality rates increased overall and across all age groups between 2000 and 2016. Fatalities for the oldest riders showed the steadiest increasing trends. Results highlight the continued public health burden of motorcyclist fatalities and, by extension, the importance of improving motorcycle safety.     

Sperm parasitism in ants: selection for interspecific mating and hybridization

Interspecific mating in eusocial Hymenoptera can be favored under certain conditions even if all hybrid offspring are completely infertile. This exploits two key features of the eusocial Hymenoptera: a haplodiploid genetic system and reproductive division of labor in females. Interspecifically mated queens can still produce viable sons that will mate intraspecifically. Apparent reduced fitness resulting from producing infertile daughter gynes can be also offset by advantages conferred by hybrid workers. An important advantage is likely to be superior ability at using marginal habitats. Interspecifically mated queens can nest in sites where intraspecific competition will be low. By mating interspecifically, a queen trades expected reproductive success through female offspring for a higher probability of achieving some reproductive success. Females that mate interspecifically can be considered "sperm parasites" on the males of the other species. I provide evidence that sperm parasitism is responsible for widespread hybridization in North America among two species of the ant subgenus Acanthomyops (genus Lasius), and review evidence for sperm parasitism in other hybridization phenomena in ants. Sperm parasitism in ants represents a novel form of social parasitism in ants and a dispersal polymorphism. It may also act as a precursor to the evolution of some other recently discovered phenomena, such as genetic caste determination.     

Motor vehicle fatalities among Gulf War era veterans: characteristics, mechanisms, and circumstances

OBJECTIVES: Our objective was to describe fatal motor vehicle crashes (MVC) among veterans of the 1991 Gulf War era and to compare the distribution of crash and individual characteristics between those deployed to the Gulf War (GWV) and those not deployed (NDV). METHODS: We compared individual characteristics, crash mechanisms, and crash circumstances between 765 GWV and 553 NDV who died from MVC within the first five years of the war, between May 1991 and December 1995. RESULTS: Overall, GWV and NDV who died from a MVC were more likely to be enlisted males (97%), 21-30 years old (72%), have a high school education or less (91%), drive a passenger car (52%), and not use restraints (60%). The overall annual rate of motor vehicle fatalities for GWV (23.6 per 100,000; 95% confidence interval: 21.9-25.3) was significantly greater than the rate for NDV (15.9, 95% CI: 14.6-17.3). GWV with the highest motor vehicle fatality rates include males (24.8, 95% CI: 23.0-26.6), 17-20 year olds (105.0, 95% CI: 78.2-138.1), and those not married (27.3, 95% CI: 25.1-30.1). Adjusting for differences in age distribution across GWV and NDV did not account for the difference in rates. Characteristics of MVC fatalities that were over-represented among GWV include serving as regular active duty (p = 0.001), having a high school education or less (p = 0.01), being involved in a single-vehicle crash (p = 0.008), and dying within the first hour following the crash (p = 0.004). Also, we identified a greater proportion of alcohol-related crashes among GWV during the late night and early morning hours. CONCLUSIONS: The highest rates of motor vehicle fatality among young, single males in the military mirror the experience of the general population. Further research is necessary to determine modifiable risk factors that can be targeted for specific interventions and whether the elevated late night alcohol-related crash rate among GWV is an effect of deployment or an inherent population bias among those selected for operational deployments.     

Organochlorine concentrations, reproductive physiology, and immune function in unique populations of freshwater Atlantic stingrays (Dasyatis sabina) from Florida's St. Johns River

Within the past decade, reproductive and health disorders have been reported to occur in unique populations of Atlantic stingrays (Dasyatis sabina) inhabiting certain components of Florida's St. Johns River. Since these irregularities are consistent with the alleged effects of organochlorine (OC) contaminant exposure in other Florida wildlife, the goal of this study was to examine possible associations between OC concentrations and reproduction and/or immune function in stingrays from this river system. Liver concentrations of 30 OC pesticides/pesticide metabolites and total polychlorinated biphenyls (PCBs) were measured and compared in D. sabina collected from four central Florida lakes of the St. Johns River: Lake George, Lake Harney, Lake Jesup, and Lake Monroe. Reproductive biology, serum testosterone and 17beta-estradiol concentrations, and circulating white blood cell counts were examined and compared in stingrays from lakes that were determined to contain low (Lake George), intermediate (Lake Monroe), and high (Lake Jesup) levels of pesticide contamination, based on the results of liver OC assessments. Successful breeding occurred in Lake Jesup stingrays, indicating that the degree of OC accumulation in these animals is not high enough to cause reproductive impairment. However, elevated serum steroid concentrations and white blood cell counts were observed in Lake Jesup stingrays, suggesting that endocrine and immune function may be altered in these animals due to OC exposure and/or other, as yet unknown, ecological factors. Inconsistencies in the reproductive success of Lake Monroe stingrays were observed, confirming earlier reports of reproductive complications in this sub-population. Based on these findings, previous occurrences of reproductive failure in St. Johns River stingrays may be due to environmental factors other than OC exposure.     

Carbon-based balanced trophic structure and flows in the offshore Lake Ontario food web before (1987-1991) and after (2001-2005) invasion-induced ecosystem change

Replicate mass-balanced solutions to Ecopath models describing carbon-based trophic structures and flows were developed for the Lake Ontario offshore food web before and after invasion-induced disruption. The food webs link two pathways of energy and matter flow: the grazing chain (phytoplankton-zooplankton-fish) and the microbial loop (bacteria-protozoans) and include 19 species-groups and three detrital groups. Mass-balance was achieved by using constrained optimization techniques to randomly vary initial estimates of biomass and diet composition. After the invasion, production declined for all trophic levels and species-groups except Chinook salmon. The trophic level (TL) increased for smelt, adult sculpin, adult alewife and Chinook salmon. Changes to ecotrophic efficiencies indicate a reduction in phytoplankton grazing, increased predation pressure on Mysis, adult smelt and alewife and decreased predation pressure on protozoans. Specific resource to consumer TTE changed; increasing for protozoans (8.0-11.5%), Mysis (0.6-1.0%), and Chinook salmon (1.0-2.3%) and other salmonines (0.4-0.5%) and decreasing for zooplankton (20.2-15.1%), prey-fish (9.7-8.8%), and benthos (1.7-0.6%). Direct trophic influences of recent invasive species were low. The synchrony of the decline in PP and species-group production indicates strong bottom-up influence. Mass balance required an increase of two to threefold in lower trophic level biomass and production, confirming a previously observed paradoxical deficit in lower trophic level production. Analysis of food web changes suggest hypotheses that may apply to other similar large pelagic systems including, (1) as pelagic primary productivity declines, overgrazing of zooplankton results in an increase in protozoan production and a loss of trophic transfer efficiency, (2) habitat and food web changes increased Mysis predation on Diporeia and contributed to their recent decline, and (3) production of Chinook salmon, the primary piscivore, was uncoupled from pelagic production processes. This study demonstrates the value of food web models to better understand the impact of invasive species and to develop novel hypotheses concerning trophic influences.     

Bias from two analytical laboratories involved in a long-term air monitoring program measuring organic pollutants in the Arctic: a quality assurance/quality control assessment

Initiated in 1992, air monitoring of organic pollutants in the Canadian Arctic provided spatial and temporal trends in support of Canada's participation in the Stockholm Convention of Persistent Organic Pollutants. The specific analytical laboratory charged with this task was changed in 2002 while field sampling protocols remained unchanged. Three rounds of intensive comparison studies were conducted in 2004, 2005, and 2008 to assess data comparability between the two laboratories. Analysis was compared for organochlorine pesticides (OCPs), polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs) in standards, blind samples of mixed standards and extracts of real air samples. Good measurement accuracy was achieved for both laboratories when standards were analyzed. Variation of measurement accuracy over time was found for some OCPs and PCBs in standards on a random and non-systematic manner. Relatively low accuracy in analyzing blind samples was likely related to the process of sample purification. Inter-laboratory measurement differences for standards (<30%) and samples (<70%) were generally less than or comparable to those reported in a previous inter-laboratory study with 21 participating laboratories. Regression analysis showed inconsistent data comparability between the two laboratories during the initial stages of the study. These inter-laboratory differences can complicate abilities to discern long-term trends of pollutants in a given sampling site. It is advisable to maintain long-term measurements with minimal changes in sample analysis.     

Phosphorus runoff losses from subsurface-applied poultry litter on coastal plain soils

The application of poultry litter to soils is a water quality concern on the Delmarva Peninsula, as runoff contributes P to the eutrophic Chesapeake Bay. This study compared a new subsurface applicator for poultry litter with conventional surface application and tillage incorporation of litter on a Coastal Plain soil under no-till management. Monolith lysimeters (61 cm by 61 cm by 61 cm) were collected immediately after litter application and subjected to rainfall simulation (61 mm h(-1) 1 h) 15 and 42 d later. In the first rainfall event, subsurface application of litter significantly lowered total P losses in runoff (1.90 kg ha(-1)) compared with surface application (4.78 kg ha(-1)). Losses of P with subsurface application were not significantly different from disked litter or an unamended control. By the second event, total P losses did not differ significantly between surface and subsurface litter treatments but were at least twofold greater than losses from the disked and control treatments. A rising water table in the second event likely mobilized dissolved forms of P in subsurface-applied litter to the soil surface, enriching runoff water with P. Across both events, subsurface application of litter did not significantly decrease cumulative losses of P relative to surface-applied litter, whereas disking the litter into the soil did. Results confirm the short-term reduction of runoff P losses with subsurface litter application observed elsewhere but highlight the modifying effect of soil hydrology on this technology's ability to minimize P loss in runoff.     

Advanced Electrostatic Stimulation of Fabric Filtration

In advanced electrostatic stimulation of fabric filtration (AESFF), a high voltage electrode is placed coaxially inside a filter bag to establish an electric field between the electrode and the bag surface. The electric field alters the dust deposition pattern within the bag, yielding a much lower pressure drop than that found in a conventional bag. Pilot plant results show that AESFF bags can operate with a rate of pressure loss that is 70 percent below that for conventional bags. The presence of the electric field also affects the aging characteristics of the AESFF bags. On the average, the AESFF bags had residual drags that were 10 percent below those of conventional bags. The results show that AESFF baghouses can yield the same pressure drop performance as conventional baghouses while operating at much higher air-to-cloth ratios. An economic analysis evaluated the capital, operating, and maintenance costs for electric utility plants ranging from 200 to 1,000 MW. For AESFF baghouses the capital cost was found to be 25 to 48 percent below that of a conventional baghouse. A lifetime cost analysis predicts a net present value for an AESFF baghouse that is 10 to 30 percent below that of a conventional baghouse.