Ontario Ministry of Transportation

About: Ontario Ministry of Transportation is a government organization based out in Toronto, Ontario, Canada. It is known for research contribution in the topics: Poison control & Asphalt. The organization has 4652 authors who have published 3882 publications receiving 59011 citations.

Effects of cannabis and alcohol on automobile driving and psychomotor tracking

Abstract: This paper is a final report on the driving and psychomotor tracking studies conducted by the Canadian Commission of Inquiry into the Non-Medical Use of Drugs (LeDain Commission). Preliminary reports of these studies appeared in the commission’s cannabis report.2s The effects of cannabis on psychomotor performance have been studied for a variety of psychomotor tasks, including skills involved in automobile driving l2 and simulated driving.*% R, 16, 22 Psychomotor abilities that have been shown to be impaired by cannabis under certain conditions include pursuit tracking a c c ~ r a c y , ~ ~ 12. 13, 18, 26 hand and body ~teadiness,~, 9 , braking stop time,l*. l6 and start time.16 Other abilities that are of likely importance in the complex skill of automobile driving that also have been shown to be adversely affected by cannabis at certain doses are short-term memory,I5 vigilance and signal detection,30. 23 and performance on divided attention tasks.* Additional areas of interest regarding driving ability and traffic safety and possible adverse or beneficial effects due to cannabis include judgmental faculties, such as the perception of danger, driver attitudes, risk taking, susceptibility to distraction or stress, and experience in driving while “high,” that is, statedependent learning.’, 10. 2’ The effects of cannabis on psychomotor abilities have frequently been shown to be related to dosage. At low dosages, effects are generally not observed, but with larger dosages, effects become apparent and progressively larger with increased d o ~ a g e . ~ The dosage relationship is complicated by the finding that

Multi-ratio equilibrium passive sampling method to estimate accessible and pore water concentrations of polycyclic aromatic hydrocarbons and polychlorinated biphenyls in sediment.

Abstract: The freely dissolved concentration (Cw,0) in the pore water and the accessible (releasable) concentration in the sediment (Cas,0) are important parameters for risk assessment. These parameters were determined by equilibrating contaminated sediments and passive samplers using largely differing sampler–sediment ratios. This method is based on the principle that incubations at low sampler/sediment ratios yield the concentration in the pore water (minor depletion of the sediment phase) and incubations at high sampler/sediment ratios yield the accessible concentration in the sediment (maximum depletion of the sediment phase). It is shown that equilibration was faster in dense suspensions and at high sampler/sediment ratios when compared to low sampler/sediment ratios. An equilibrium distribution model was used to estimate Cw,0 and Cas,0 by nonlinear least-squares regression. The method was evaluated for three sediments (harbor, estuarine, marine). Accessible concentrations of 13 PAHs were 2 (low Kow) to 10 (hi...

Numerical computation of unsteady incompressible flow in complex geometry using a composite multigrid technique

Abstract: This paper presents a composite multigrid method and its application to a geometrically complex flow. The treatment of the interior boundary conditions within a composite multigrid strategy described in detail for a 1D model equation. For the Navier-Stokes equations a staggered grid technique is adopted for spatial discretisation and a fractional step method is used for the time advance. Lid-driven cavity flows are used to demonstrate the effectiveness of the method.

Effect of oxygen status on pesticide transformation and sorption in undisturbed soil and lake sediment

Abstract: The behavior of four chemically distinctly different pesticides (aldicarb, simazine, mecoprop, and phenoxic acid [MCPA] was investigated under simulated redox conditions that occur at the terrestrial-aqueous interface. Sorption was measured in soil and lake sediment and in pure and combined pesticide solutions to study effects of competition. Transformation was investigated in undisturbed soil microcolumns and in anaerobic lake sediment. Using an air-tight nitrogen incubator, oxygen concentrations were varied from 20.8% (ambient) to less then 0.01 % v/v O 2 , while redox potentials varied from +330 to -120 mV. Aldicarb was transformed more rapidly under anaerobic than under aerobic conditions. Under low oxygen conditions, both reductive and oxidative metabolites were formed. Simazine showed some reductive transformation, but the overall transformation rate decreased with decreasing O 2 concentrations. A pronounced redox effect was shown for both mecoprop and MCPA. With decreasing oxygen concentrations, transformation rates decreased from 0.173 to less than 0.001 d ', monitored over 200 d. These compounds, which are considered improbable leachers based on their short aerobic half lifes, appear to be more persistent in low-oxygenous conditions. It is shown that a period of oxygen inhibition could be survived by the responsible soil microorganisms and was followed by accelerated transformation of the compound when oxygen became abundant again. No relationship was observed between sorption affinity and transformation rate. The effect of redox conditions that occur along the pesticide's emission route appears to be an important screening parameter to assess environmental risks.