Predictability of clinical assessments for driving performance

PROBLEM: As the number of older drivers grows, it is increasingly important to accurately identify at-risk drivers. This study tested clinical assessments predictive of real-time driving performance. METHOD: Selected assessment tools considered important in the identification of at-risk older drivers represented the domains of vision, cognition, motor performance, and driving knowledge. Participants were administered the battery of assessments followed by an on-road test. A univariate analysis was conducted to identify significant factors (<.05) to be included in a multivariate regression model. RESULTS: Assessments identified as independently associated with driving performance in the regression model included: FACTTM Contrast sensitivity slide-B, Rapid Pace Walk, UFOV rating, and MMSE total score. DISCUSSION: The domains of vision, cognitive, and motor performance were represented in the predictive model. SUMMARY: Due to the dynamic nature of the driving task, it is not likely that a single assessment tool will identify at risk drivers. IMPACT ON INDUSTRY: By standardizing the selection of clinical assessments used in driving evaluations, practitioners should be able to provide services more efficiently, more objectively, and more accurately to identify at-risk drivers.     

Phosphate treatment of firing range soils: lead fixation or phosphorus release?

Phosphate treatment of lead (Pb)-contaminated soils relies on the premise that Pb converts to the thermodynamically stable, insoluble mineral class of pyromorphites. Recent research showed that treatment performance is kinetically controlled and strongly dependent on soil pH; this study employed an acidic phosphate (P) form, monobasic calcium phosphate (MCP), to investigate treatment performance of Pb occurring in an alkaline-buffered and an acidic firing range soil. The results of leaching, X-ray powder diffraction (XRPD), and modeling analyses showed that P and Pb dissolution in the alkaline soil and transformation reactions were kinetically controlled, so that: (i) TCLP (toxicity characteristic leaching procedure) and SPLP (synthetic precipitation leaching procedure) results were poor to marginal even at high MCP dosages; (ii) brushite (Ca(HPO(4)).2H(2)O) and cerussite (PbCO(3)) persisted in XRPD patterns; and, (iii) geochemical modeling failed to predict leaching and phase assemblages. In the acidic soil, Pb-P reactions promoted further soil acidification, improved TCLP performance, and generated better agreement with the equilibrium-based model; however, SPLP and modeling results showed that Pb concentrations could not be reduced below 15 microg/L mainly due to the low soil pH. The marginal or inadequate Pb immobilization was observed in both soils despite the elevated MCP dosages, which were well in excess of the pyromorphite stoichiometric ratio (P/Pb = 0.6). Additionally, P leaching concentrations and rates were extremely high (>300 mg/L), under both SPLP and deionized (DI) water extraction conditions, and as predicted by thermodynamic equilibrium. The performance and sustainability of phosphate-based treatment therefore seem questionable.     

Influence of fipronil compounds and rice-cultivation land-use intensity on macroinvertebrate communities in streams of southwestern Louisiana, USA

Laboratory tests of fipronil and its degradation products have revealed acute lethal toxicity at very low concentrations (LC50) of <0.5 microg/L to selected aquatic macroinvertebrates. In streams draining basins with intensive rice cultivation in southwestern Louisiana, USA, concentrations of fipronil compounds were an order of magnitude larger than the LC50. The abundance (rho=-0.64; p=0.015) and taxa richness (r2=0.515, p<0.005) of macroinvertebrate communities declined significantly with increases in concentrations of fipronil compounds and rice-cultivation land-use intensity. Macroinvertebrate community tolerance scores increased linearly (r2=0.442, p<0.005) with increases in the percentage of rice cultivation in the basins, indicating increasingly degraded stream conditions. Similarly, macroinvertebrate community-tolerance scores increased rapidly as fipronil concentrations approached about 1 microg/L. Pesticide toxicity index determinations indicated that aquatic macroinvertebrates respond to a gradient of fipronil compounds in water although stream size and habitat cannot be ruled out as contributing influences.     

Modeling riverine nutrient transport to the Baltic Sea: a large-scale approach

We developed for the first time a catchment model simulating simultaneously the nutrient land-sea fluxes from all 105 major watersheds within the Baltic Sea drainage area. A consistent modeling approach to all these major watersheds, i.e., a consistent handling of water fluxes (hydrological simulations) and loading functions (emission data), will facilitate a comparison of riverine nutrient transport between Baltic Sea subbasins that differ substantially. Hot spots of riverine emissions, such as from the rivers Vistula, Oder, and Daugava or from the Danish coast, can be easily demonstrated and the comparison between these hot spots, and the relatively unperturbed rivers in the northern catchments show decisionmakers where remedial actions are most effective to improve the environmental state of the Baltic Sea, and, secondly, what percentage reduction of riverine nutrient loads is possible. The relative difference between measured and simulated fluxes during the validation period was generally small. The cumulative deviation (i.e., relative bias) [Sigma(Simulated - Measured)/Sigma Measured x 100 (%)] from monitored water and nutrient fluxes amounted to +8.2% for runoff, to -2.4% for dissolved inorganic nitrogen, to +5.1% for total nitrogen, to +13% for dissolved inorganic phosphorus and to +19% for total phosphorus. Moreover, the model suggests that point sources for total phosphorus compiled by existing pollution load compilations are underestimated because of inconsistencies in calculating effluent loads from municipalities.     

Mining investment in Africa

Since 1985, there has been rapid growth in the presence of Australian exploration and mining companies in Africa. This paper sets out the reasons for the interest of those companies, now 20 in number, in various African mineral opportunities. Australian companies spent about US$16 million in 1992 on African exploration and evaluation, with over US$130 million spent on new mine development or expansion. The 20 Australian companies operate in 16 African countries, with two areas of focus, West Africa and Southern Africa. Using the responses to a survey sent to Australian companies operating in Africa in 1991, and to companies known to be interested in prospects there, the paper identifies and categorizes the policy and regulatory requirements needed by investors. Although a gloomy picture has often been painted of investment in Africa, Australian companies recognize that their risk taking, in the light of a declining investment climate in other mining areas, could promote a renaissance of world-scale mining in Africa.     

Passive vapor monitoring of underground storage tanks for leak detection

Passive vapor monitoring of underground storage tanks (USTs) containing volatile hydrocarbons at locations external to the tank (an external system) is touted as a fast and effective method of leak detection. However, major gaps remain in our knowledge of the physical processes that relate a measured vapor concentration to the leak rate, thus making network design according to a quantitative design criterion nearly impossible, and differentiation between surface spills and a leaking UST requires certain levels of sophistication in the leak detection system and in the analysis that are not usually available. Heavier-than-air vapors from the constituents of stored hydrocarbons could result in a density-driven convective propagation component that complicates the design of leak detection systems, and finally, detection times are highly sensitive to concentration detection threshold levels set by the system. The use of inadequate systems and analyses can lead to either wasted efforts or excessive subsurface contamination. This paper discusses the physical processes involved, explores the above aspects of external passive vapor leak detection design, and suggests some alternatives as they pertain to gasoline service stations.     

Variations in occupant response with seat belt slack and anchor location during moderate frontal impacts

Both seat belt slack and anchor location are known to affect occupant excursion during high-speed frontal collisions, but their effects have not been studied at moderate collision severities. The goal of this study was to quantify how seat belt slack and anchor location affect occupant kinematics and kinetics in moderate severity frontal collisions. A Hybrid III 50th percentile male dummy was seated on a programmable sled and exposed to frontal collisions with a speed change of 17.5 km/h. The seat belt was adjusted either snugly or with 10 cm slack (distributed 60/40 between the shoulder and lap portions) and the anchor location was varied by adjusting the seat position either fully forward or rearward (seat travel = 13 cm). Accelerations and displacements of the head, T1 and pelvis were measured in the sagittal plane. Upper neck loads and knee displacements were also measured. Five trials were performed for each of the four combinations of belt adjustment (snug, slack) and anchor location (seat forward, seat rearward). For each trial, kinematic and kinetic response peaks were determined and then compared across conditions using ANOVAs. Peak displacements, accelerations and loads varied significantly with both seat belt slack and anchor location. Seat belt slack affected more parameters and had a larger effect than anchor location on most peak response parameters. Head displacements increased a similar amount between the snug/slack belt conditions and the rearward/forward anchor locations. Overall, horizontal head displacements increased from 23.8 cm in the snug-belt, rearward-anchor configuration to 33.9 cm in the slack-belt, forward-anchor configuration. These results demonstrated that analyses of occupant displacements, accelerations and loads during moderate frontal impacts should consider potential sources of seat belt slack and account for differences in seat belt anchor locations.     

RESIDUAL POWER AND ECONOMIC FEASIBILITY OF A SOLAR POWERED IRRIGATION SYSTEM1

ABSTRACT: The problem of nonmatching irrigation and solar power production seasons creates the problem of what to do with the surplus power. The economic law of opportunity cost dictates that substitution for currently commercially purchased power is the best use for this power. This law also allows for new power using enterprises that satisfy specific criteria to be used on the farm before sale of the residual to a local public utility can be considered. Economic and Financial Evaluation of the solar powered irrigation system show that the price of commercially purchased power must reach 9.5 cents per Kwh before the system is feasible under the ideal assumption of complete use of the residual power to substitute for commercially purchased power.     

Pressure drop in electrostatic fabric filtration

Fabric filtration systems have been employed in industry for over a century with relatively few technological modifications. However, with the recent substantial increase in energy costs, conservation in energy consumption has become vitally important. As a result, the filtration systems of yesteryear may not be the best approach for future applications. Recently, an external electrical field was considered in fabric filtration of industrial dust with very promising initial results. An increase in the collection efficiency, particularly for fine particulates, and a decrease in the pressure drop was observed. In this paper the further results of an experimental program in the investigation of pressure drop in the electrostatic fabric filtration in industrial dust control are presented. The basic apparatus, a bench-scale electrostatic fabric filtration system, creates a representative dust cake under specific conditions of operating parameters and charge levels. The results clearly indicate that filter and dust cake resistance, or pressure drop, decreases substantially with the increased electrostatic field strength for all industrial dust samples tested, regardless of fabric type and other relevant parameters.