Analysis of running child pedestrians impacted by a vehicle using rigid-body models and optimization techniques

Lack of information from vehicle-to-child pedestrian impacts provides considerable challenges when developing vehicle countermeasures for the pediatric population. Crash reconstructions of real-world incidents provide useful information about the vehicle damage and injury outcome but do not permit definitive and quantitative measures of the impact severity given the high level of uncertainty in the initial conditions of the pedestrian and the vehicle prior the impact. This paper develops an advanced methodology for reconstructing child pedestrian–vehicle impacts that combines the crash data with multi-body simulations and optimization techniques for identifying the pedestrian posture and vehicle speed prior to impact. For the child pedestrian posture, a continuous sequence of the running gait was developed based on the literature data and simulations. Using vehicle damage information from an actual child pedestrian crash, an objective function was developed that minimized the difference between vehicle and pedestrian contact points for the simulated child postures, pedestrian, and vehicle speeds. Simulated annealing and genetic optimization algorithms were used to identify sets of potential solutions for the pedestrian and vehicle initial conditions. Local minimums were observed for several response surfaces of the objective function which shows the non-convex nature of the crash reconstruction optimization problem with the chosen objective function. Based on the results of the real-world reconstruction, this study indicates that numerical simulations coupled with heuristic optimization algorithms can be used to reconstruct child pedestrian and vehicle pre-impact conditions.     

Multispecies remote sensing measurements of vehicle emissions on Sherman Way in Van Nuys,California

As part of the 2010 Van Nuys tunnel study, researchers from the University of Denver measured on-road fuel-specific light-duty vehicle emissions from nearly 13,000 vehicles on Sherman Way (0.4 miles west of the tunnel) in Van Nuys, California, with its multispecies Fuel Efficiency Automobile Test (FEAT) remote sensor a week ahead of the tunnel measurements. The remote sensing mean gram per kilogram carbon monoxide (CO), hydrocarbon (HC), and oxide of nitrogen (NO_x) measurements are 8.9% lower, 41% higher, and 24% higher than the tunnel measurements, respectively. The remote sensing CO/NO_x and HC/NO_x mass ratios are 28% lower and 20% higher than the comparable tunnel ratios. Comparisons with the historical tunnel measurements show large reductions in CO, HC, and NO_x over the past 23 yr, but little change in the HC/NO_x mass ratio since 1995. The fleet CO and HC emissions are increasingly dominated by a few gross emitters, with more than a third of the total emissions being contributed by less than 1% of the fleet. An example of this is a 1995 vehicle measured three times with an average HC emission of 419 g/kg fuel (two-stroke snowmobiles average 475 g/kg fuel), responsible for 4% of the total HC emissions. The 2008 economic downturn dramatically reduced the number of new vehicles entering the fleet, leading to an age increase (>1 model year) of the Sherman Way fleet that has increased the fleet's ammonia (NH₃) emissions. The mean NH₃ levels appear little changed from previous measurements collected in the Van Nuys tunnel in 1993. Comparisons between weekday and weekend data show few fleet differences, although the fraction of light-duty diesel vehicles decreased from the weekday (1.7%) to Saturday (1.2%) and Sunday (0.6%).

Implications: On-road remote sensing emission measurements of light-duty vehicles on Sherman Way in Van Nuys, California, show large historical emission reductions for CO and HC emissions despite an older fleet arising from the 2008 economic downturn. Fleet CO and HC emissions are increasingly dominated by a few gross emitters, with a single 1995 vehicle measured being responsible for 4% of the entire fleet's HC emissions. Finding and repairing and/or scrapping as little as 2% of the fleet would reduce on-road tailpipe emissions by as much as 50%. Ammonia emissions have locally increased with the increasing fleet age.     

Alteration of antioxidant enzymes and impairment of DNA in the SiO2 nanoparticles exposed zebra fish (Danio rerio)

The incorporation of nanoparticles in industrial and biomedical applications has increased significantly in recent years, yet their hazardous and toxic effects have not been studied extensively. While standard toxicological test methods are generally capable of detecting the toxic effects, the choice of relevant methods for nanomaterials is still discussed. Among the various oxide nanomaterials, silica nanoparticles are widely used in biological applications that include nano-medicine. But studies on adverse effects of silica nanoparticle exposure to fish remain unclear. Therefore, the present study was designed to investigate the oxidative toxic effects of silicon dioxide nanoparticles using fish model. The size of the SiO₂ nanoparticles was between 68 and 100 nm which was confirmed by X-ray diffractometer, dynamic light scattering, scanning electron microscope and transmission electron microscope. The zebra fish were exposed to sub-lethal concentrations (5 and 2.5 mg/L) of characterized SiO₂ nanoparticles for a period of 7 days. After 7 days, SiO₂ nanoparticle-treated fishes were sacrificed, and tissues such as liver, muscle and gill were dissected out for the analysis of antioxidant enzymes and DNA fragmentation. The DNA profiles were analysed in the tissues of zebra fish that treated with SiO₂ nanoparticles. Tissues of fish from clean water were used as control, and DNA profiles were analysed. It is found that DNA from control tissues was intact, whereas the tissues treated with SiO₂ were all fragmented. SiO₂ nanoparticle-mediated antioxidant enzymes activities, such as catalase, superoxide dismutase, glutathione (GSH)-S-transferase, glutathione reductase and GSH, in the tissues of zebra fish were measured. The results revealed that alteration of antioxidant enzymes due to SiO₂ nanoparticle can be considered as a biomarker to SiO₂-mediated oxidative stress in biological samples.     

Using computational fluid dynamics (CFD) for blast wave predictions

Explosions will, in most cases, generate blast waves. While simple models (e.g., Multi Energy Method) are useful for simple explosion geometries, most practical explosions are far from trivial and require detailed analyses. For a reliable estimate of the blast from a gas explosion it is necessary to know the explosion strength. The source explosion may not be symmetric; the pressure waves will be reflected or deflected when hitting objects, or even worse, the blast waves may propagate inside buildings or tunnels with a very low rate of decay. The use of computational fluid dynamics (CFD) explosion models for near and far field blast wave predictions has many advantages. These include more precise estimates of the energy and resulting pressure of the blast wave, as well as the ability to evaluate non-symmetrical effects caused by realistic geometries, gas cloud variations and ignition locations. This is essential when evaluating the likelihood of a given leak source as cause of an explosion or equally when evaluating the potential risk associated with a given leak source for a consequence analysis.In addition, unlike simple methods, CFD explosion models can also evaluate detailed dynamic effects in the near and far field, which include time dependent pressure loads as well as reflection and focusing of the blast waves. This is particularly valuable when assessing actual near-field blast damage during an explosion investigation or potential near-field damage during a risk analysis for a facility. One main challenge in applying CFD, however, is that these models require more information about the actual facility, including geometry details and process information. Collecting the necessary geometry and process data may be quite time consuming. This paper will show some blast prediction validation examples for the CFD model FLACS. It will also provide examples of how directional effects or interaction with objects can significantly influence the dynamics of the blast wave. Finally, the challenge of obtaining useful predictions with insufficient details regarding the geometry will also be addressed.     

Engineered nanoparticles in wastewater and wastewater sludge – Evidence and impacts

Nanotechnology has widespread application in agricultural, environmental and industrial sectors ranging from fabrication of molecular assemblies to microbial array chips. Despite the booming application of nanotechnology, there have been serious implications which are coming into light in the recent years within different environmental compartments, namely air, water and soil and its likely impact on the human health. Health and environmental effects of common metals and materials are well-known, however, when the metals and materials take the form of nanoparticles – consequential hazards based on shape and size are yet to be explored. The nanoparticles released from different nanomaterials used in our household and industrial commodities find their way through waste disposal routes into the wastewater treatment facilities and end up in wastewater sludge. Further escape of these nanoparticles into the effluent will contaminate the aquatic and soil environment. Hence, an understanding of the presence, behavior and impact of these nanoparticles in wastewater and wastewater sludge is necessary and timely. Despite the lack of sufficient literature, the present review attempts to link various compartmentalization aspects of the nanoparticles, their physical properties and toxicity in wastewater and wastewater sludge through simile drawn from other environmental streams.     

Relationships Between Nitrogen Transformation Rates and Gene Abundance in a Riparian Buffer Soil

Denitrification is a critical biogeochemical process that results in the conversion of nitrate to volatile products, and thus is a major route of nitrogen loss from terrestrial environments. Riparian buffers are an important management tool that is widely utilized to protect water from non-point source pollution. However, riparian buffers vary in their nitrate removal effectiveness, and thus there is a need for mechanistic studies to explore nitrate dynamics in buffer soils. The objectives of this study were to examine the influence of specific types of soluble organic matter on nitrate loss and nitrous oxide production rates, and to elucidate the relationships between these rates and the abundances of functional genes in a riparian buffer soil. Continuous-flow soil column experiments were performed to investigate the effect of three types of soluble organic matter (citric acid, alginic acid, and Suwannee River dissolved organic carbon) on rates of nitrate loss and nitrous oxide production. We found that nitrate loss rates increased as citric acid concentrations increased; however, rates of nitrate loss were weakly affected or not affected by the addition of the other types of organic matter. In all experiments, rates of nitrous oxide production mirrored nitrate loss rates. In addition, quantitative polymerase chain reaction (qPCR) was utilized to quantify the number of genes known to encode enzymes that catalyze nitrite reduction (i.e., nirS and nirK) in soil that was collected at the conclusion of column experiments. Nitrate loss and nitrous oxide production rates trended with copy numbers of both nir and 16s rDNA genes. The results suggest that low-molecular mass organic species are more effective at promoting nitrogen transformations than large biopolymers or humic substances, and also help to link genetic potential to chemical reactivity.     

A Lost Link between a Flightless Parrot and a Parasitic Plant and the Potential Role of Coprolites in Conservation Paleobiology

Late Quaternary extinctions and population fragmentations have severely disrupted animal‐plant interactions globally. Detection of disrupted interactions often relies on anachronistic plant characteristics, such as spines in the absence of large herbivores or large fruit without dispersers. However, obvious anachronisms are relatively uncommon, and it can be difficult to prove a direct link between the anachronism and a particular faunal taxon. Analysis of coprolites (fossil feces) provides a novel way of exposing lost interactions between animals (depositors) and consumed organisms. We analyzed ancient DNA to show that a coprolite from the South Island of New Zealand was deposited by the rare and threatened kakapo (Strigops habroptilus), a large, nocturnal, flightless parrot. When we analyzed the pollen and spore content of the coprolite, we found pollen from the cryptic root‐parasite Dactylanthus taylorii. The relatively high abundance (8.9% of total pollen and spores) of this zoophilous pollen type in the coprolite supports the hypothesis of a former direct feeding interaction between kakapo and D. taylorii. The ranges of both species have contracted substantially since human settlement, and their present distributions no longer overlap. Currently, the lesser short‐tailed bat (Mystacina tuberculata) is the only known native pollinator of D. taylorii, but our finding raises the possibility that birds, and other small fauna, could have once fed on and pollinated the plant. If confirmed, through experimental work and observations, this finding may inform conservation of the plant. For example, it may be possible to translocate D. taylorii to predator‐free offshore islands that lack bats but have thriving populations of endemic nectar‐feeding birds. The study of coprolites of rare or extinct taxonomic groups provides a unique way forward to expand existing knowledge of lost plant and animal interactions and to identify pollination and dispersal syndromes. This approach of linking paleobiology with neoecology offers significant untapped potential to help inform conservation and restoration plans. Un Eslabón Perdido entre un Loro No Volador y una Planta Parásita y el Papel Potencial de Coprolitos en Paleobiología de la Conservación     

Investigating phosphorus limitation in a fixed bed filter with phosphorus and nitrogen profile measurements

In 2000, the European Union adopted the European Water Framework Directive (WFD) (European Commission, 2000). The WFD focuses on increasingly stringent nutrient standards including ultra low nitrogen (< 2.2 mg N-total/L) and phosphorus concentrations (< 0.15 mg total phosphorus/L) in receiving surface waters and in relevant point sources like wastewater treatment plant (WWTP) effluent. Expansion of WWTPs with advanced post-treatment processes, like effluent filtration, is widely proposed to meet possible future effluent discharge standards. When combining biological nitrate-nitrogen and chemical phosphorus removal in one filter, phosphorus limitation in the denitrifying process may occur. This study investigated where in the filter bed and under which conditions phosphorus limitation occurs. Profile measurements for nitrate, nitrite, and orthophosphorus (PO4-P) combined with chemical oxygen demand (COD) and 02 were conducted. Results showed that the required PO4-P/NOx-N ratio is approximately 0.006 mg/mg after phosphorous precipitation and flocculation. Profile measurements have proven to be an applicable and useful tool. It showed how nitrate and orthophosphorus are removed through the filter bed based on the PO4-P/NOx-N ratio. When orthophosphorus is removed more rapidly and efficiently compared to nitrate, the PO4-P/NOx-N ratio decreases. When PO4-P/NOx-N ratio thresholds are approximately 0.006 mg/mg for a certain period of time and water temperatures varied significantly, orthophosphorus limitation may occur. Changing the filter-bed configuration or decreasing the coagulant dosage can prevent limitation of the denitrifying process because of a phosphorous shortage.     

Exploring the Crowding–Satisfaction Relationship in Recreational Boating

Along with the growing boating population and the number of boats in use on limited inland waterways, boater expectations of setting density, safety perceptions, and the associated impacts on their experience (e.g., satisfaction) are becoming increasingly important. The primary purpose of this article was to explore a recreational boating crowding–satisfaction model derived from previous work using safety and enjoyment as mediating variables. We also tested our crowding–satisfaction model among day and overnight users. Our analysis revealed no significant difference between day and overnight users for any of the relationships tested in our model. Our final model indicated as respondents’ expectations for seeing people increased along with their feelings of being crowded, they were more inclined to consider the conditions on the lake as being unsafe. They were also more inclined to indicate that the number of people they had seen on the lake detracted from their boating experience. Respondents’ satisfaction was tied to their perceptions of crowding. Mediating variables illustrated that the relationship was conditioned by perceptions of safety and enjoyment. Analysis of the indirect effect observed in our study illustrate that when the number of people seen on the lake exceed respondents’ expectations, their perceptions of safety and enjoyment both decline, resulting in lower satisfaction. These findings have implications for managing recreational boating use on inland lake systems. Given the role played by expectations in our model, efforts to communicate with boaters about conditions on these waterways is important for helping them plan their boating experience and avoid situations they consider unsafe or unsatisfactory.     

Phytopumping for hydraulic control of an arsenic plume

Phytoremediation, the use of plants for in situ contaminant cleanup, is gaining new appreciation as an aesthetically pleasing, sustainable method that naturally makes use of solar power. Hybrid poplars are widely used because they grow rapidly and have high transpiration rates, making them advantageous for hydraulic control of groundwater. However, the tendency for trees and other vegetation to uptake metals may be a disadvantage in some settings due to potential redistribution of metals from groundwater to the ground surface. Therefore, a pilot test in the upper midwestern United States was implemented to evaluate the applicability of poplars to groundwater withdrawal and metals transport. © 2009 Wiley Periodicals, Inc.