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Mallory M.L.,Acadia University | Braune B.M.,Carleton University | Provencher J.F.,Carleton University | Callaghan D.B.,Acadia University | And 5 more authors.
Marine Pollution Bulletin | Year: 2015

Mercury (Hg) concentrations are a concern in the Canadian Arctic, because they are relatively high compared to background levels and to similar species farther south, and are increasing in many wildlife species. Among marine birds breeding in the Canadian Arctic, Hg concentrations have been monitored regularly in eggs and intermittently in livers, but feathers have generally not been used as an indicator of Hg exposure or burden. We examined Hg concentrations in six marine bird species in the Canadian Arctic. Ivory gull Pagophila eburnea, feather Hg was exceptionally high, while glaucous gull Larus hyperboreus feather Hg was unexpectedly low, and ratios of feather THg to egg THg varied across species. The proportion of total Hg that was comprised of methyl Hg in ivory gull feathers was lower than in other species, and may be related to photo-demethylation or keratin breakdown in semi-opaque feather tissue. © 2015 Elsevier Ltd.


Tong H.,U.S. Environmental Protection Agency | Rappold A.G.,U.S. Environmental Protection Agency | Caughey M.,University of North Carolina at Chapel Hill | Hinderliter A.L.,University of North Carolina at Chapel Hill | And 5 more authors.
Inhalation Toxicology | Year: 2014

Context: Epidemiological studies have shown an association between the incidence of adverse cardiovascular effects and exposure to ambient particulate matter (PM). Diesel exhaust (DE) is a major contributor to ambient PM and gaseous emissions in urban areas. Objective: This was a pilot study designed to evaluate concentration-dependent effects of short-term exposure to whole DE on the cardiovascular system in order to identify a threshold concentration that can elicit biological responses in healthy human volunteers. Materials and methods: Six healthy middle-aged participants with glutathione-S-transferase-Mu 1 (GSTM1) null genotype underwent sequential exposures to 100g/m, 200g/m, and 300g/m whole DE generated in real time using an idling diesel truck engine. Exposures were separated by 14d and each was 2h in duration. Results: We report concentration-dependent effects of exposure to DE, with 100g/m concentration causing minimal cardiovascular effects, while exposure to 300g/m DE for 2h resulted in a borderline significant reduction of baseline brachial artery diameter (3.34±0.27mm pre- versus 3.23±0.25mm post-exposure; p=0.08). Exposure to the highest concentration of DE also resulted in increases of 5mmHg in diastolic blood pressure as well as a decrease in indices of the frequency domain of heart rate variability (HRV). Discussion and conclusions: These findings demonstrate that acute exposure to relatively high concentrations of DE produces cardiovascular changes in middle-aged GSTM1 null individuals. This study therefore suggests that arterial vasoconstriction and changes in HRV are responses through which traffic-related air pollution increases the risk of adverse cardiovascular outcomes. © 2014 Informa Healthcare USA, Inc. All rights reserved: reproduction in whole or part not permitted.


Knight A.,U.S. Department of Agriculture | Light D.,U.S. Department of Agriculture | Chebny V.,Trc Inc.
Environmental Entomology | Year: 2012

Polyvinyl chloride polymer (PVC) dispensers loaded with ethyl (E,Z)-2,4-decadienoate (pear ester) plus the sex pheromone, (E,E)-8,10- dodecadien-1-ol (codlemone) of codling moth, Cydia pomonella (L.), were compared with PVC dispensers and a commercial dispenser (Isomate-C Plus) loaded with codlemone. Evaluations were conducted in replicated plots (0.10.2 ha) in apple, Malus domestica (Borkhausen) during both generations of codling moth from 2007 to 2009. Dispensers were applied at 1,000 ha -1 Male captures in traps baited with virgin female moths and codlemone lures were recorded. Residual analysis of field-aged dispensers over both moth generations was conducted. Dispensers exhibited linear declines in release rates of both attractants, and pear ester was released at a significantly higher rate than codlemone during both time periods. The proportion of virgin female-baited traps catching males was significantly lower with combo dispenser TRE24 (45/110, mg codlemone/mg pear ester) during the second generation in 2007 and the combo dispensers TRE144 (45/75) and TRE145 (75/45) during the first generation in 2008 compared with Isomate-C Plus. Similarly, male catches in female-baited traps in plots treated with the combo dispensers TRE144 during the first generation in 2008 and TRE23 (75/110) during the second generation, in 2007 were significantly lower than in plots treated with Isomate-C Plus. No significant differences were found for male catches in codlemone-baited traps in plots treated with Isomate-C Plus and any of the combo dispensers. However, male catches were significantly lower in plots treated with Cidetrak CM (codlemone-only dispenser) than the combo TRE144 dispenser during both generations in 2009. © 2012 Entomological Society of America.


Murray D.R.,TRC Corporation | Newman M.B.,TRC Corporation
Air and Waste Management Association - Guideline on Air Quality Models 2013: The Path Forward | Year: 2013

In order to calculate total concentrations for comparison to ambient air quality standards, monitored background concentrations are often combined with model predicted concentrations. The "Guideline on Air Quality Models" and various memoranda from EPA's Air Quality Modeling Group provide instructions to determine background concentrations and combine those concentrations with model predictions. The Guideline method includes the use of meteorological data to define a downwind sector for exclusion of monitored data and this technique is evaluated. Further, models have low skill in predicting the locations or time series of observed concentrations and adding the quantile-quantile distributions of monitored and predicted concentrations is very conservative and not mathematically correct. Simply adding the 99th percentile predicted to the 99th percentile background will not yield the 99th percentile of the combined distributions. By using the definition of independent variables, the joint probability of the simultaneous occurrence of hourly background and modeled concentrations is investigated and a method for combining modeled and background concentration is proposed. Using a model evaluation database appearing on EPA's SCRAM website, the consequences of combining modeled and background concentrations following Guideline recommendations versus the form of the one-hour National Ambient Air Quality Standards are reported.


Taylor R.,TRC Inc.
2011 64th Annual Conference for Protective Relay Engineers | Year: 2011

Directional Ground Overcurrent Relays have been an essential component in protection of transmission lines for as long as any of us have been around. Their role has been to provide protection for ground faults by applications that have included an instantaneous element in combination with an inverse time overcurrent element. Recent years have seen a rapid evolution in transmission line protective relays to microprocessor based transmission relays that provide a wide variety of functions that include both phase and ground impedance relay elements. The widespread availability of ground distance protection has led many companies to de-emphasize, or even stop using, directional ground overcurrent protection. This evolution has also resulted in a significant portion of existing DGOC relays that have not been regularly evaluated or maintained to assure proper settings and applications. © 2011 IEEE.


Murray D.R.,TRC Corporation | Newman M.B.,TRC Corporation
Journal of the Air and Waste Management Association | Year: 2014

In order to calculate total concentrations for comparison to ambient air quality standards, monitored background concentrations are often combined with model predicted concentrations. Models have low skill in predicting the locations or time series of observed concentrations. Further, adding fixed points on the probability distributions of monitored and predicted concentrations is very conservative and not mathematically correct. Simply adding the 99th percentile predicted to the 99th percentile background will not yield the 99th percentile of the combined distributions. Instead, an appropriate distribution can be created by calculating all possible pairwise combinations of the 1-hr daily maximum observed background and daily maximum predicted concentration, from which a 99th percentile total value can be obtained. This paper reviews some techniques commonly used for determining background concentrations and combining modeled and background concentrations. The paper proposes an approach to determine the joint probabilities of occurrence of modeled and background concentrations. The pairwise combinations approach yields a more realistic prediction of total concentrations than the U.S. Environmental Protection Agency's (EPA) guidance approach and agrees with the probabilistic form of the National Ambient Air Quality Standards. Implications: EPA's current approaches to determining background concentrations for compliance modeling purposes often lead to "double counting" of background concentrations and actual plume impacts and thus lead to overpredictions of total impacts. Further, the current Tier 1 approach of simply adding the top ends of the background and model predicted concentrations (e.g., adding the 99th percentiles of these distributions together) results in design value concentrations at probabilities in excess of the form of the National Ambient Air Quality Standards. © 2014 Copyright 2014 A&WMA.


Trademark
TRC Inc. | Date: 2011-12-05

Scripts, namely, computer software employed and used in robotic devices for operating interactive robots.


Trademark
TRC Inc. | Date: 2011-12-05

Scripts, namely, computer software employed and used in robotic devices for operating interactive robots.

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