Search

This article is the third of a five-part series covering various aspects of occupational thyroid monitoring. This article introduces the basic concepts required to understand the procedure for determining the counting efficiency of a thyroid detector. The B.R.M.D. thyroid-neck phantom is used as the calibration source. A procedure for personnel monitoring is also discussed and the concept of Minimum Detectable Activity (MDA) is introduced. The last two articles in this series discuss energy calibration, counting system optimization based on a single-channel analyzer and placement error minimization.

Efficiency of hydrological models mostly depends on the quality of the calibration performed prior to use. In this paper, an automatic calibration framework for the distributed hydrological model HYDROTEL is proposed. The calibration procedure was performed for three watersheds characterized with different hydroclimatological conditions: the Sassandra located in Ivory Coast, Africa, and the Montmorency and Beaurivage watersheds located in Quebec (Canada). Results of one-a-time (OAT) sensitivity analysis showed that the order of the most sensitive parameters differs for each watershed. Thus, the sensitivity depends on the hydroclimatic and physiographic characteristics of the watersheds. Co-linearity indices showed that all model parameters were identifiable, that is, none of the studied parameters could be explained by a combination of the other parameters. Following these findings, an automatic calibration was run. Results indicated there was good agreement between simulated and measured streamflows at the outlet of each watershed; Nash-Sutcliffe efficiency (NSE) ranging between 0.77 and 0.92 and R2 ranging from 0.87 to 0.97. When comparing NSE and R2 values obtained using a process-oriented, multiple-objective, manual calibration strategy, a slight increase in model efficiency was reached with the automatic calibration procedure (4.15% for NSE and 2.95% for R2) improving predictions of peak flows for the Montmorency and Beaurivage watersheds (temperate climate conditions) and flows beyond the rainfall season in the Sassandra watershed. The proposed automatic calibration procedure introduced in this paper may be applied to other distributed hydrological model. Copyright © 2013 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Copyright of Canadian Water Resources Journal / Revue Canadienne des Ressources Hydriques is the property of Taylor & Francis Ltd and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This is a report on observations of 17 Cepheid variable stars in the Andromeda Galaxy, from Simon Fraser University's Trottier Observatory. The observatory is a teaching and public outreach facility with a 0.7-m aperture telescope under suburban skies. The observations were done as a group project by a team that included students, staff, and faculty at the university, and members of the Vancouver Centre of The Royal Astronomical Society of Canada. The Cepheid periods range from about 7 to 44 days, and observations were made on 26 nights over the course of two years. Images were taken through a luminance filter, and the instrumental magnitudes were converted to the Johnson-Cousins F-band using a calibration procedure whose precision is thoroughly characterized. The mean apparent magnitudes range from about 19.3 to 20.7, and they exhibit a correlation with the period that clearly reproduces the famous period-luminosity relation discovered by Henrietta Leavitt. We estimated the distance modulus m (difference between apparent and absolute magnitudes) using a well-established calibration of the Leavitt relation, along with a correction for interstellar extinction from a professional study of this region of M31. We obtained μ = 24.37 ± 0.21, which is in excellent agreement with the known value, and corresponds to a distance of 2.44 ± 0.25 million light-years. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Small Business & Entrepreneurship is the property of Routledge and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Over the years, structural engineering codes and specifications in Canada and elsewhere have moved from an allowable stress design (ASD) approach to a load and resistance factor design (LRFD) philosophy. LRFD methodology takes better account of the inherent variability in both loading and resistance by providing different factors of safety for loads of distinct natures with regard to their probability of overload, frequency of occurrences and changes in point of application. The method also results in safer structures because it considers the behavior at collapse. While resistance factors for traditional construction materials based on LRFD in the National Building Code (NBC) of Canada are available, they cannot be used for non-conventional ones. This is because the resistance of such materials due to various load effects has unique bias factors (λR) and coefficients of variation (VR), which greatly impact their reliability index (β). In this study, relationships between the resistance factor ϕ and critical load effects from the NBC load combinations at ultimate limit states are developed for a wide range of resistance bias factors and coefficients of variation. The relationships are presented in the form of charts that are useful for researchers and code-writing professionals who have expertise in the various fields of structural engineering but lack proper background in reliability theory. The developed spectra showed that for the same ϕ, β increases with an increase in the live-to-dead load (L/D) ratio until it reaches 1; thereafter, the shape of the relationship will depend on the statistics of the resistance as well as on the magnitude of ϕ. For a small ϕ and VR, β will keep increasing with an increase in the L/D ratio from 1 until 3, albeit at a lesser rate. For L/D > 3, the relationship between the critical β and applied load is just about constant. This finding is also true for load combinations involving snow and wind. Application of the method is illustrated by a practical example involving the shear strength of a corrugated web steel beam. [ABSTRACT FROM AUTHOR]

The Root Zone Water Quality Model (RZWQM) is a one-dimensional process-based model used for simulating major physical, chemical, and biological processes in agricultural systems. To date, the model has not been applied to potato production systems for simulating nitrate leaching. In this study, 35 datasets collected between 2009 and 2016 at a field under a three-year potato (potato–barley–red clover) rotation in Prince Edward Island (PEI), Canada, have been employed for calibrating and validating the water, nitrogen (N) cycling, and plant growth routines of RZWQM and for subsequently estimating nitrate leaching. The model fitness, evaluated using univariate and bivariate indicators, was rated as high for most of the parameters tested. As a result of the combined influence of higher infiltration and reduced plant uptake, the model showed that the highest leaching at the rotation level occurred between September and December. A secondary leaching period occurred in spring, when residual soil nitrate was mobilized by increased percolation due to snowmelt. Most of the nitrate leaching occurred during the potato year (89.9 kg NO3–N ha−1 y−1), while leaching for barley and red clover years had comparable values (28.6 and 29.7 kg NO3–N ha−1 y−1, respectively). The low N use efficiency of the entire rotation (i.e., 30.2%), combined with the high NO3–N concentration in leachate (i.e., 34.9 mg NO3–N L−1 for potato and 16.3 mg NO3–N L−1 for the complete rotation), suggest that significant efforts are required for adapting management practices to ensure sustainability of potato production systems. [ABSTRACT FROM AUTHOR]

Glacier melt provides important contributions to streamflow in many mountainous regions. Hydrologic model calibration in glacier-fed catchments is difficult because errors in modelling snow accumulation can be offset by compensating errors in glacier melt. This problem is particularly severe in catchments with modest glacier cover, where goodness-of-fit statistics such as the Nash-Sutcliffe model efficiency may not be highly sensitive to the streamflow variance associated with glacier melt. While glacier mass balance measurements can be used to aid model calibration, they are absent for most catchments. We introduce the use of glacier volume change determined from repeated glacier mapping in a guided GLUE (generalized likelihood uncertainty estimation) procedure to calibrate a hydrologic model. This approach is applied to the Mica basin in the Canadian portion of the Columbia River Basin using the HBV-EC hydrologic model. Use of glacier volume change in the calibration procedure effectively reduced parameter uncertainty and helped to ensure that the model was accurately predicting glacier mass balance as well as streamflow. The seasonal and inter-annual variations in glacier melt contributions were assessed by running the calibrated model with historic glacier cover and also after converting all glacierized areas to alpine land cover in the model setup. Sensitivity of modelled streamflow to historic changes in glacier cover and to projected glacier changes for a climate warming scenario was assessed by comparing simulations using static glacier cover to simulations that accommodated dynamic changes in glacier area. Although glaciers in the Mica basin only cover 5% of the watershed, glacier ice melt contributes up to 25% and 35% of streamflow in August and September, respectively. The mean annual contribution of ice melt to total streamflow varied between 3 and 9% and averaged 6%. Glacier ice melt is particularly important during warm, dry summers following winters with low snow accumulation and early snowpack depletion. Although the sensitivity of streamflow to historic glacier area changes is small and within parameter uncertainties, our results suggest that glacier area changes have to be accounted for in future projections of late summer streamflow. Our approach provides an effective and widely applicable method to calibrate hydrologic models in glacier fed catchments, as well as to quantify the magnitude and timing of glacier melt contributions to streamflow. [ABSTRACT FROM AUTHOR]

Highlights • Trajectory-based calibration of simulation model parameters for safety analysis is investigated. • Automated computer vision techniques are used to extract vehicle trajectories and traffic conflicts. • High correlation between simulated and field-measured conflicts was found after calibration. • The results show that using simulation to evaluate safety without proper calibration should be avoided. • The calibration parameters varied considerably among different traffic environments. Abstract The primary objective of this study is to investigate the relationship between field-measured conflicts and simulated conflicts estimated from the surrogate safety assessment model (SSAM) for two signalized intersections in Brisbane, Australia. Traffic video data collected from the two signalized intersections (left-hand traffic regulations) were used for analysis. Automated computer vision analysis techniques were used to extract vehicle trajectories and identify field-measured conflicts. Simulated conflicts were obtained using VISSIM and SSAM tool. A two-step calibration procedure was performed to test the correlation between simulated and field-measured conflicts. In addition, the spatial distributions of simulated and field-measured conflicts were compared. Finally, the calibration results for the left-hand traffic environment were compared with results for signalized intersections in Canada and China (right-hand traffic environment). The results indicated a good correlation between simulated and field-measured conflicts, especially at higher TTC thresholds. However, major differences between field-measured and simulated conflict spatial distributions indicate that despite the good correlation obtained via calibration, simulated conflicts do not adequately capture the actual conflict occurrence mechanism. It was also found that there were significant differences between the left-hand and right-hand traffic environments calibration results. [ABSTRACT FROM AUTHOR]

Copyright of Canadian Geotechnical Journal is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Mathematical models in engineering play an important role in understanding and predicting the behavior of a system. A mechanistic coupled liquid water, water vapor and heat transfer model incorporating kinetic phase change accounting for real‐time interfacial area between water and gas phases was developed to predict coupled subsurface processes and evaporation (drying) rates from bare soils. To enhance the model capability to predict evaporation rates, the air resistance associated with the viscous sublayer was implemented in energy and mass exchange across the soil‐air interface (the land‐atmosphere boundary condition [BC]). The atmospheric stability condition was also considered in the calculation of sensible heat and vapor fluxes at the ground surface. This comprehensive model was validated against measured field data from bare soil test plots from a green roof study, during temperate summer conditions in Canada, demonstrating that the model captured the main coupled processes in the subsurface of bare soil during drying periods. A sensitivity analysis was performed to determine the importance of various components of the comprehensive model. Removal of viscous sublayer resistance in the vapor transfer BC resulted in poorer predictions of evaporation (drying) rates. Incorporating the atmospheric stability function accounting for real‐time atmospheric conditions did not improve the predictive capability for the simulated drying events compared to the case when only a neutral atmospheric condition was implemented. Neglecting heat transfer associated with hydrodynamic dispersion of water vapor in the subsurface had limited impact on subsurface temperature predictions. Key Points: The developed non‐equilibrium based model adequately predicted subsurface non‐isothermal processes under various weather conditionsThe inclusion of viscous sublayer resistance in ground surface vapor transfer boundary condition improved the predicted evaporation ratesA lack of incorporation of some subsurface processes in coupled model has limited impact on the simulation of evaporation for bare soils [ABSTRACT FROM AUTHOR]

Copyright of American Journal of Potato Research is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The Saskatchewan River Basin (SRB) of central Canada plays a crucial role in the Canadian Prairies. Yet, climate change and human action constitute a real threat to its hydrological processes. This study aims to evaluate and analyze groundwater spatial and temporal dynamics in the SRB. Groundwater information was derived and compared using two different approaches: (1) a mathematical modeling framework coupling the Soil and Water Assessment Tool (SWAT) and the Modular hydrologic model (MODFLOW) and (2) gravimetric satellite observations from the Gravity Recovery and Climate Experiment (GRACE) mission and its follow-on (GRACE-FO). Both methods show generalized groundwater depletion in the SRB that can reach −1 m during the study period (2002–2019). Maximum depletion appeared especially after 2011. The water balance simulated by SWAT-MODFLOW showed that SRB could be compartmented roughly into three main zones. The mountainous area in the extreme west of the basin is the first zone, which is the most dynamic zone in terms of recharge, reaching +0.5 m. The second zone is the central area, where agricultural and industrial activities predominate, as well as potable water supplies. This zone is the least rechargeable and most intensively exploited area, with depletion ranging from +0.2 to −0.4 m during the 2002 to 2011 period and up to −1 m from 2011 to 2019. Finally, the third zone is the northern area that is dominated by boreal forest. Here, exploitation is average, but the soil does not demonstrate significant storage power. Briefly, the main contribution of this research is the quantification of groundwater depletion in the large basin of the SRB using two different methods: process-oriented and satellite-oriented methods. The next step of this research work will focus on the development of artificial intelligence approaches to estimate groundwater depletion from a combination of GRACE/GRACE-FO and a set of multisource remote sensing data. [ABSTRACT FROM AUTHOR]

Reliable, long-term records of glacier mass change are invaluable to the glaciological and climate-change communities and used to assess the importance of glacier wastage on streamflow. Here we evaluate the in-situ observations of glacier mass change for Place (1982–2020) and Peyto glaciers (1983–2020) in western Canada. We use geodetic mass balance to calibrate a physically-based mass-balance model coupled with an ice dynamics routine. We find large discrepancies between the glaciological and geodetic records for the periods 1987–1993 (Place) and 2001–2006 (Peyto). Over the period of observations, the exclusion of ice dynamics in the model increased simulated cumulative mass change by ~10.6 (24%) and 7.1 (21%) m w.e. for Place and Peyto glacier, respectively. Cumulative mass loss using geodetic, modelled and glaciological approaches are respectively − 30.5 ± 4.5, − 32.0 ± 3.6, − 29.7 ± 3.6 m w.e. for Peyto Glacier (1982–2017) and − 45.9 ± 5.2, − 43.1 ± 3.1, − 38.4 ± 5.1 m w.e. for Place Glacier (1981–2019). Based on discrepancies noted in the mass-balance records for certain decades (e.g. 1990s), we caution the community if these data are to be used for hydrological model development. [ABSTRACT FROM AUTHOR]

This paper overviews our recent results of energy market modeling, including The option pricing formula for a mean-reversion asset, variance and volatility swaps on energy markets, applications of weather derivatives on energy markets, pricing crude oil options using the Lévy processes, energy contracts modeling with delayed and jumped volatilities, applications of mean-reverting processes on Alberta energy markets, and alternatives to the Black-76 model for options valuation of futures contracts. We will also consider the clean renewable energy prospective in Canada, and, in particular, in Alberta and Calgary. [ABSTRACT FROM AUTHOR]

This paper presented a two-dimensional, well-balanced hydrodynamic and sediment transport model based on the solutions of variable-density shallow-water equations (VDSWEs) and the Exner equation for bed change for simulating sediment transport in unsteady flows. Those equations are solved in a coupled way by the first-order Godunov-type finite volume method. The Harten–Lax–van Leer–Contact (HLLC) Riemann solver is extended to find the local Riemann fluxes to maintain the exact balance between the momentum term and the bed slope term. A well-balanced scheme is superior to an unbalanced scheme to minimize numerical dispersion as demonstrated by the synthetic standing contact-discontinuity test case. Following this, the model is employed to simulate two laboratory experiments and a field case, the 1996 Lake Ha! Ha! flood event in Canada. The results of water surface elevations and bed surface profiles agree well with the measurements. The accuracy and robustness of the numerical schemes make the model a good candidate for practical engineering applications. [ABSTRACT FROM AUTHOR]

The paper describes load and resistance factor design (LRFD) calibration for the resistance factor used in the Stiffness Method internal stability soil failure limit state for geogrid mechanically stabilized earth (MSE) walls. The Stiffness Method was recently adopted in the current American Association of State Highway and Transportation Officials LRFD Bridge Design Specifications in the US, and will appear in the next edition of the Canadian Highway Bridge Design Code. The paper describes the details of the calibration of the soil failure limit state which is unique to the Stiffness Method. Calibration outcomes include consideration of the concept of level of understanding in the selection of nominal load and resistance values which is unique to LRFD foundation engineering practice in Canada. A practical conclusion from these calculations is that if product line-specific creep test data are available to estimate the reinforcement secant creep stiffness used for design, then a resistance factor of 1.0 is reasonable for US practice. If only minimum average roll value tensile strength data are available, then a value of 0.95 is recommended for US practice. For Canadian practice, the corresponding values for typical level of understanding are 0.90 and 0.85, respectively. [ABSTRACT FROM AUTHOR]

High-resolution multispectral imaging of agricultural fields is expensive but helpful in detecting subtle variations in plant health and stress symptoms before the appearance of visible indications. To aid precision agriculture (PA) practices, an innovative and inexpensive protocol for robust and timely monitoring of vegetation symptoms has been evaluated. This innovative but inexpensive protocol uses machine vision (MV) and generative adversarial networks (GAN) to translate red-green-blue (RGB) imagery captured with unmanned aerial vehicle (UAV) into a valuable normalized difference vegetation index (NDVI) map. This study used direct translation of RGB imagery in NDVI index, in contrast with similar studies that used GANs in near-infrared (NIR) translation. The protocol was tested by flying a fixed-winged UAV developed by senseFly Inc. (Cheseaux-sur-Lausanne, Switzerland) model Ebee-X, equipped with a RedEdge-MX sensor, to capture images from five different potatoes fields located in Prince Edward Island – Canada, during the growing season of 2021. The images were captured throughout the growing season under vegetation (15–30 DAP; days after plantation), tuber formation (30–45 DAP), tuber bulking (75–110 DAP), and tuber maturation stages (> 110 DAP). The NDVI was calculated from captured UAV aerial surveys using NIR and red bands to develop pairwise datasets for the training of GANs. Five hundred pairwise images were used (80% training, 10% validation, and 10% testing) for training and evaluation of GANs. Two famous GANs, namely Pix2Pix and Pix2PixHD, were tested compared to various training and evaluation indicators. The Pix2PixHD outperformed Pix2Pix GAN by recording lower root mean square error (RMSE) (5.40 to 13.73) and higher structural similarity index matrix (SSIM) score (0.69 to 0.90) during the evaluation of the protocol. The results of this study are breakthroughs to be used for economic vegetation and orchard health monitoring after the training of models. The trained GANs can translate simple RGB domains into useful vegetation indices maps for variable rate PA practices. This innovative protocol can also translate remote sensing imagery of large-scale agricultural fields and commercial orchards into NDVI to extract useful information about plant health indicators. [ABSTRACT FROM AUTHOR]

How much wetland we should protect or restore is not a simple question, such that conservation targets are often set according to political agendas, then standardized globally. However, given their key regulating hydrological functions, wetlands represent nature-based solutions to the anticipated, exacerbating effect of climate change on drought and flood events, which will vary at the regional scale. Here, we propose a science-based approach to establishing regional wetland restoration targets centered on their hydrological functions, using a case study on several sub-watersheds of a northern temperate basin in south-eastern Canada. We posit that restoration targets should minimally mitigate the negative effects of climate change on watershed hydrology, namely peak and low flows. We used a semi-distributed hydrological model, HYDROTEL, to perform a hydroclimatic assessment, including 47 climate projections over the 1979–2099 period, to test the effect of wetland restoration scenarios on peak and low flows. The results showed that hydrological responses to climate change varied among sub-watersheds (even at the scale of a relatively small region), and that, to mitigate these changes, increases in wetland coverage should be between 20% and up to 150%. At low restoration levels, increasing wetland coverage was more effective in attenuating floods than alleviating droughts. This study indicates that a no-net-loss policy is insufficient to maintain current hydrological cycles in the face of climate change; rather, a 'net gain' in wetland cover is needed. [ABSTRACT FROM AUTHOR]

The Red River is one of the largest contributing sources of discharge and nutrients to the world's 10th largest freshwater lake, Lake Winnipeg. Conversion of large areas of annual cropland to perennial forage has been proposed as a strategy to reduce both flooding and nutrient export to Lake Winnipeg. Such reductions could occur either via a reduction in the concentration of nutrients in runoff or through changes in the basin-scale hydrology, resulting in a lower water yield and the concomitant export of nutrients. This study assessed the latter mechanism by using the physically based Cold Regions Hydrological Modelling platform to examine the hydrological impacts of land use conversion from annual crops to perennial forage in a subbasin of the La Salle River basin in Canada. This basin is a typical agricultural subbasin in the Red River Valley, characterised by flat topography, clay soils, and a cold subhumid, continental climate. Long-term simulations (1992–2013) of the major components of water balance were compared between canola and smooth bromegrass, representing a conversion from annual cropping systems to perennial forage. An uncertainty framework was used to represent a range of fall soil saturation status (0 % to 70 %), which governs the infiltration to frozen soil in the subsequent spring. The model simulations indicated that, on average, there was a 36.5 ± 6.6 % (36.5 ± 7.2 mm) reduction in annual cumulative discharge and a 29.9 ± 16.3 % (2.6 ± 1.6 m 3 s -1) reduction in annual peak discharge due to forage conversion over the assessed period. These reductions were driven by reduced overland flow 52.9 ± 12.8 % (28.8 ± 10.1 mm), increased peak snowpack (8.1 ± 1.5 %, 7.8 ± 1.6 mm), and enhanced infiltration to frozen soils (66.7 ± 7.7 %, 141.5 ± 15.2 mm). Higher cumulative evapotranspiration (ET) from perennial forage (34.5 ± 0.9 %, 94.1 ± 2.5 mm) was also predicted by the simulations. Overall, daily soil moisture under perennial forage was 18.0 % (57.2 ± 1.2 mm) higher than that of crop simulation, likely due to the higher snow water equivalent (SWE) and enhanced infiltration. However, the impact of forage conversion on daily soil moisture varied interannually. Soil moisture under perennial forage stands could be either higher or lower than that of annual crops, depending on antecedent spring snowmelt infiltration volumes. [ABSTRACT FROM AUTHOR]

In recent decades, advances in the flexibility and complexity of hydrologic models have enhanced their utility in scientific studies and practice alike. However, the increasing complexity of these tools leads to a number of challenges, including steep learning curves for new users and issues regarding the reproducibility of modelling studies. Here, we present the RavenR package, an R package that leverages the power of scripting to both enhance the usability of the Raven hydrologic modelling framework and provide complementary analyses that are useful for modellers. The RavenR package contains functions that may be useful in each step of the model-building process, particularly for preparing input files and analyzing model outputs. The utility of the RavenR package is demonstrated with the presentation of six use cases for a model of the Liard River basin in Canada. These use cases provide examples of visually reviewing the model configuration, preparing input files for observation and forcing data, simplifying the model discretization, performing realism checks on the model output, and evaluating the performance of the model. All of the use cases are fully reproducible, with additional reproducible examples of RavenR functions included with the package distribution itself. It is anticipated that the RavenR package will continue to evolve with the Raven project and will provide a useful tool to new and experienced users of Raven alike. [ABSTRACT FROM AUTHOR]

Throughout history, pandemics have forced societies to think beyond typical management and control protocols. The main goals of this study were to simulate and understand the spatial dynamics of COVID-19 spread and assess the efficacy of two policy measures in Montreal, Canada, to mitigate the COVID-19 outbreak. We simulated the COVID-19 outbreak using a Geographical Information System (GIS)-based agent-based model (ABM) and two management scenarios as follows: (1) human mobility reduction; and (2) observation of self-isolation. The ABM description followed the ODD (Overview, Design concepts, Details) protocol. Our simulation experiments indicated that the mainstream of COVID-19 transmissions (i.e., approximately 90.34%) occurred in public places. Besides, the results indicated that the rules aiming to reduce population mobility, led to a reduction of about 63 infected people each week, on average. Furthermore, our scenarios revealed that if instead of 42% (i.e., the adjusted value in the calibration), 10%, 20%, and 30% of infectious people had followed the self-isolation measure, the number of infected people would have risen by approximately 259, 207, and 83 more each week, on average, respectively. The map of critical locations of COVID-19 spreading resulted from our modeling and the evaluated effectiveness of two control measures on the COVID-19 outbreak could assist health policymakers to navigate through the pandemic. [ABSTRACT FROM AUTHOR]

Copyright of Canadian Journal of Economics is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The failure process of brittle rocks under compression involves the initiation, accumulation and propagation of tensile fractures before peak stress is reached. This process is influenced by the internal microstructure and the presence of heterogeneities in rock, creating localized concentrations of tensile stresses. A realistic simulation of this process requires an explicit representation of rock heterogeneities. The Voronoi tessellation technique is commonly used in numerical methods to simulate heterogeneities in brittle rocks. In this approach, the model domain is divided into several randomly generated polygonal Voronoi blocks separated by numerical 'joint' elements. This modelling approach is referred to as a Voronoi Tessellated Model (VTM). Discontinuum-based VTMs provide a better representation of the brittle rock failure process compared to conventional continuum methods. However, their higher computational costs may limit their practical applicability. In this study, a continuum-based VTM was developed using a two-dimensional finite element program to simulate the failure of Lac du Bonnet granite under laboratory and field loading conditions. For this purpose, the VTM with inelastic blocks and block boundaries was first calibrated to the intact (undamaged) rock strength obtained from laboratory tests and then to the rock mass strength estimated based on a tri-linear, brittle failure criterion. The calibrated VTMs were then used to simulate the brittle failure around a circular test tunnel at Canada's Underground Research Laboratory (URL). As expected, the model calibrated to the intact rock strength did not capture the observed failure; however, the VTM calibrated to the tri-linear criterion did successfully replicate the observed V-shaped notch failure and damage zone around the test tunnel. Highlights: A heterogeneous continuum model was developed to simulate the brittle failure around a test tunnel at Canada's Underground Research Laboratory. The heterogeneous continuum model calibrated to the laboratory peak strength of Lac du Bonnet granite did not adequately capture the observed V-shaped notch failure. The heterogeneous continuum model calibrated to the tri-linear failure criterion successfully simulated the observed V-shaped notch failure and the excavation damaged zone. The back analysis of the V-shaped notch failure using the calibrated model resulted in a spalling limit (σ1/σ3) of 11.2 for the granite. [ABSTRACT FROM AUTHOR]

The water distribution system hydraulic model for an Ontario, Canada town has been calibrated by engineers familiar with the system. Their calibration procedure was mainly an expert-based approach using judgment and trial-and-error and did not rely on optimization. The purpose of this study is to resolve the corresponding calibration problem with optimization tools and compare the calibration solutions in terms of quality (closeness to measured data) and calibration parameter values. The calibration problem is posed as a multi-objective optimization problem and solved with the PA-DDS algorithm described in [1]. The precise calibration objectives are roughly matched to the manual calibration objectives specified by the engineers who calibrated the model. Multi-objective optimization results are compared with the current solution to determine if the current solution is non-dominated. [ABSTRACT FROM AUTHOR]

Copyright of Hydrogeology Journal is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Atmosphere -- Ocean (Taylor & Francis Ltd) is the property of Taylor & Francis Ltd and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The representation of snow processes in forest growth models is necessary to accurately predict the hydrological cycle in boreal ecosystems and the isotopic signature of soil water extracted by trees, photosynthates and tree-ring cellulose. Yet, most process-based models do not include a snow module; consequently, their simulations may be biased in cold environments. Here, we modified the MAIDENiso model to incorporate a new snow module that simulates snow accumulation, melting and sublimation, as well as thermal exchanges driving freezing and thawing of the snow and the soil. We tested these implementations in two sites in eastern and western Canada for black spruce (Picea mariana (Mill.) B.S.P.) and white spruce (Picea glauca (Moench) Voss) forests, respectively. The new snow module improves the skills of the model to predict components of the hydrological cycle. The MAIDENiso model is now able to reproduce the spring discharge peak and to simulate stable oxygen isotopes in tree-ring cellulose more realistically than in the original snow-free version of the model. The new implementation also results in simulations with a higher contribution from the source water on the oxygen isotopic composition of the simulated cellulose, leading to more accurate estimates of cellulose isotopic composition. Future work may include the development of inverse modelling with this new version of MAIDENiso to produce robust reconstructions of the hydrological cycle and isotope processes in cold environments. [ABSTRACT FROM AUTHOR]

Using a multi‐region heterogeneous‐firm trade model, this paper develops a method to decompose volumes and values of domestic sales, bilateral trade, total production and consumption into their intensive and extensive margins. With the free‐entry condition, the extensive margin is further decomposed into two subcategories: operating‐extensive margin and entrance/exit‐extensive margin. This method can provide ex ante predictions on gains and losses in the margins of member and nonmember countries following a trade agreement. We apply our decomposition methods to quantitatively analyse the impacts of CETA between Canada and the European Union on the world processed food industry. [ABSTRACT FROM AUTHOR]

Changes in climate are altering the historical characteristics of the streamflow regime and affecting the performance of water systems. Here, the role of representing natural streamflow conditions in quantification of water system vulnerability under changing climate is evaluated in the Oldman River Basin, Canada. Four hydrological models are developed using point- and grid-based climate data and considering lumped and semi-distributed representations of the watershed. These hydrological models are then coupled with a reservoir water allocation model. Using an ensemble of climate model projections fed into these integrated models, changes in the water system's behaviour are evaluated. Although intensified and earlier peak flows and more critical water deficits are projected, the estimated risks of failure strongly depend on the considered hydrological model configuration. The divergence among models' projections for water deficit can be as high as 300%. Therefore, usage of all configurations is recommended to revise the reservoir operational policies. [ABSTRACT FROM AUTHOR]

Groundwater recharge (GWR) is a strategic hydrologic variable, and its estimate is necessary to implement sustainable groundwater management. This is especially true in a global warming context that highly impacts key winter conditions in cold and humid climates. For this reason, long-term simulations are particularly useful for understanding past changes in GWR associated with changing climatic conditions. However, GWR simulation at the regional scale and for long-term conditions is challenging, especially due to the limited availability of spatially distributed calibration data and due to generally short observed time series. The objective of this study is to demonstrate the relevance of using a water budget model to understand long-term transient and regional-scale GWR in cold and humid climates where groundwater observations are scarce. The HydroBudget model was specifically developed for regional-scale simulations in cold and humid climate conditions. The model uses commonly available data such as runoff curve numbers to describe the study area, precipitation and temperature time series to run the model, and river flow rates and baseflow estimates for its automatic calibration. A typical case study is presented for the southern portion of the Province of Quebec (Canada, 36 000 km 2). With the model simultaneously calibrated on 51 gauging stations, the first GWR estimate for the region was simulated between 1961 and 2017 with very little uncertainty (≤ 10 mm/yr). The simulated water budget was divided into 41 % runoff (444 mm/yr), 47 % evapotranspiration (501 mm/yr), and 12 % GWR (139 mm/yr), with preferential GWR periods during spring and winter (44 % and 32 % of the annual GWR, respectively), values that are typical of other cold and humid climates. Snowpack evolution and soil frost were shown to be a key feature for GWR simulation in these environments. One of the contributions of the study was to show that the model sensitivity to its parameters was correlated with the average air temperature, with colder watersheds more sensitive to snow-related parameters than warmer watersheds. Interestingly, the results showed that the significant increase in precipitation and temperature since the early 1960s did not lead to significant changes in the annual GWR but resulted in increased runoff and evapotranspiration. In contrast to previous studies of past GWR trends in cold and humid climates, this work has shown that changes in past climatic conditions have not yet produced significant changes in annual GWR. Because of their relative ease of use, water budget models are a useful approach for scientists, modelers, and stakeholders alike to understand regional-scale groundwater renewal rates in cold and humid climates, especially if they can be easily adapted to specific study needs and environments. [ABSTRACT FROM AUTHOR]

Electron density measured at high latitudes by the Swarm satellites is compared with the measurements by the RISR incoherent scatter radars as the satellites fly by the radars' field of views near Resolute Bay, Canada between 2014 and 2019. More than 200 satellite passes crossing multiple radar beams are considered. Overall, the Swarm-based electron densities are smaller than those measured by the radars by ∼30%. The values are closer to one another at electron densities between 3 10 10 and 15 1010 3 m, corresponding to plasma frequencies between 1.5 and 3.5 MHz. Swarm-measured values are getting progressively smaller than those measured by radars at larger electron densities/plasma frequencies. For the entire range of measured electron densities, the slope of the best fit linear line to the data expressed in terms of electron density is ∼0.62 and offset is 2 1010 3 m. Stronger differences between the instruments were found for observations at nighttime and dawn. [ABSTRACT FROM AUTHOR]

The Isotrace CNRS workgroup in collaboration with National Research Council of Canada has characterized a number of trace element mass fractions and isotope ratios currently not certified in AQUA-1 natural drinking water reference material (NRC Canada). This survey further expands the use of this material as a tool for environmental quality control, method validation, and method development tool for the international community. Simultaneously, the SLRS-6 river water was analyzed as quality control and also in order to compare both water characteristics, which were sampled in the same area but having undergone different treatment. Mass fractions for B, Cs, Li, Ga, Ge, Hf, Nb, P, Rb, Rh, Re, S, Sc, Se, Si, Sn, Th, Ti, Tl, W, Y, Zr, REEs, and six isotopic ratios are proposed for Sr and Pb. Measurements were mostly performed using ICP-MS with various calibration approaches. The results are reported as consensus or indicative values depending on the number of available datasets, with their associated uncertainties. [ABSTRACT FROM AUTHOR]

Sparse precipitation information can result in uncertainties in hydrological modeling practices. Precipitation observation network augmentation is one way to reduce the uncertainty. Meanwhile, in basins with snowpack-dominated hydrology, in the absence of a high-density precipitation observation network, assimilation of in situ and remotely sensed measurements of snowpack state variables can also provide the possibility to reduce flow estimation uncertainty. Similarly, assimilation of existing precipitation observations into gridded numerical precipitation products can alleviate the adverse effects of missing information in poorly instrumented basins. In Canada, the Regional Deterministic Precipitation Analysis (RDPA) data from the Canadian Precipitation Analysis (CaPA) system have been increasingly applied for flow estimation in sparsely gauged Nordic basins. Moreover, CaPA-RDPA data have also been applied to establish observational priorities for augmenting precipitation observation networks. However, the accuracy of the assimilated data should be validated before being applicable in observation network assessment. The assimilation of snowpack state variables has proven to significantly improve streamflow estimates, and therefore, it can provide the benchmark against which the impact of assimilated precipitation data on streamflow simulation can be compared. Therefore, this study introduces a parsimonious framework for performing a proxy validation of the precipitation-assimilated products through the application of snow assimilation in physically based hydrologic models. This framework is demonstrated to assess the observation networks in three boreal basins in Yukon, Canada. The results indicate that in most basins, the gridded analysis products generally enjoyed the level of accuracy required for accurate flow simulation and therefore were applied in the meteorological network assessment in those cases. [ABSTRACT FROM AUTHOR]

Several global datasets of glacier thickness exist, but the number of observations from western Canada are sparse and spatially biased. To supplement these limited observations, we measured ice thickness with ice penetrating radar on five glaciers in the Columbia Mountains, Canada. Our radar surveys, when combined with previous surveys for two glaciers in the Rocky Mountains, total 182 km of transects that represent 34 672 point measurements of ice thickness. Our measurements are, on average, 38% thicker than previous surface inversion model estimates of glacier thickness. Using our measurements within a cross-validation scheme, we model ice thickness with the Open Global Glacier Model (OGGM) driven with recent observations of surface mass balance and glacier elevation. We calibrated OGGM ice thickness by optimizing the ice creep parameter in the model. The optimized OGGM yields an ice volume for Columbia Basin of 122.5 ± 22.4 km3 for the year 2000, which is 23% greater than the range of previous estimates. At current rates of glacier mass loss for this region, glaciers would disappear from the basin in about 65–80 years. Disappearance of these glaciers will negatively affect the basin's surface hydrology, freshwater availability and aquatic ecosystems. [ABSTRACT FROM AUTHOR]

Copyright of Canadian Journal of Civil Engineering is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Purpose: Studies have controversially suggested that prostate cancer, the most common cancer among Western men, is less common among those with a high intake of tomato products and lycopene. We examine multivariable associations between the intake of tomatoes and lycopene, and risk of prostate cancer.Methods: In a prospective study of 27,934 Adventist men without prevalent cancer, Cox proportional hazard regression analyses were used to address the objectives. Dietary measurement error was partially corrected with regression calibration.Results: 1226 incident cases of prostate cancer, 355 of them aggressive, were identified during 7.9 years of follow-up. Consumption of canned and cooked tomatoes more than four times a week was associated with a HR = 0.72 (95% CI 0.55, 0.94, P = 0.02) comparing to risk in those never consuming this food. Treating this as a continuous variable, adjusting for confounders, produces a similar result, HR = 0.86 (95% CI 0.75, 0.99), comparing 64 g/day with zero intakes (questionnaire data). Regression calibration, although less precise, suggests a yet stronger and statistically significant inverse relationship, comparing a 24-h dietary recall intake of 71 g/day canned and cooked tomato product, with zero intake. Uncalibrated multivariable-adjusted competing risk analyses do not find differences in tomato associations between aggressive and non-aggressive prostate cancers although power for aggressive cancers is limited.Conclusion: Consumption of canned and cooked tomatoes may reduce the risk of prostate cancer. These products contain more available lycopene. However, an observational study cannot exclude confounding by some unidentified, prostate cancer preventive factor. Clinical Trial Registry: ClinicalTrials.gov Identifier: NCT03615599. [ABSTRACT FROM AUTHOR]

During spring 2011, an extreme flood occurred along the Richelieu River located in southern Quebec, Canada. The Richelieu River is the last section of the complex Richelieu basin, which is composed of the large Lake Champlain located in a valley between two large mountains. Previous attempts in reproducing the Richelieu River flow relied on the use of simplified lumped models and showed mixed results. In order to prepare a tool to assess accurately the change of flood recurrences in the future, a state‐of‐the‐art distributed hydrological model was applied over the Richelieu basin. The model setup comprises several novel methods and data sets such as a very high resolution river network, a modern calibration technique considering the net basin supply of Lake Champlain, a new optimization algorithm, and the use of an up‐to‐date meteorological data set to force the model. The results show that the hydrological model is able to satisfactorily reproduce the multiyear mean annual hydrograph and the 2011 flow time series when compared with the observed river flow and an estimation of the Lake Champlain net basin supply. Many factors, such as the quality of the meteorological forcing data, that are affected by the low density of the station network, the steep terrain, and the lake storage effect challenged the simulation of the river flow. Overall, the satisfactory validation of the hydrological model allows to move to the next step, which consists in assessing the impacts of climate change on the recurrence of Richelieu River floods. Plain Language Summary: In order to study the 2011 Richelieu flood and prepare a tool capable of estimating the effects of climate change on the recurrence of floods, a hydrological model is applied over the Richelieu basin. The application of a distributed hydrological model is useful to simulate the flow of all the tributaries of the Richelieu basin. This new model setup stands out from past models due to its distribution in several hydrological units, its high‐resolution river network, the calibration technique, and the high‐resolution weather forcing data set used to drive the model. The model successfully reproduced the 2011 Richelieu River flood and the annual hydrograph. The simulation of the Richelieu flow was challenging due to the contrasted elevation of the Richelieu basin and the presence of the large Lake Champlain that acts as a reservoir and attenuates short‐term fluctuations. Overall, the application was deemed satisfactory, and the tool is ready to assess the impacts of climate change on the recurrence of Richelieu River floods. Key Points: An advanced high‐resolution distributed hydrological model is applied over a U.S.‐Canada transboundary basinThe simulated net basin supply of Lake Champlain and the Richelieu River discharge are in good agreement with observations of the 2011 floodThe flow simulation is challenging due to the topographic and meteorological complexities of the basin and uncertainties in the observations [ABSTRACT FROM AUTHOR]

Tree-ring archives are one of the main sources of information to reconstruct climate variations over the last millennium with annual resolution. The links between tree-ring proxies and climate have usually been estimated using statistical approaches, assuming linear and stationary relationships. Both assumptions may be inadequate, but this issue can be overcome by ecophysiological modelling based on mechanistic understanding. In this respect, the model MAIDEN (Modeling and Analysis In DENdroecology) simulating tree-ring growth from daily temperature and precipitation, considering carbon assimilation and allocation in forest stands, may constitute a valuable tool. However, the lack of local meteorological data and the limited characterization of tree species traits can complicate the calibration and validation of such a complex model, which may hamper palaeoclimate applications. The goal of this study is to test the applicability of the MAIDEN model in a palaeoclimate context using as a test case tree-ring observations covering the 20th century from 21 Eastern Canadian taiga sites and 3 European sites. More specifically, we investigate the model sensitivity to parameter calibration and to the quality of climatic inputs, and we evaluate the model performance using a validation procedure. We also examine the added value of using MAIDEN in palaeoclimate applications compared to a simpler tree-growth model, i.e. VS-Lite. A Bayesian calibration of the most sensitive model parameters provides good results at most of the selected sites with high correlations between simulated and observed tree growth. Although MAIDEN is found to be sensitive to the quality of the climatic inputs, simple bias correction and downscaling techniques of these data improve significantly the performance of the model. The split-sample validation of MAIDEN gives encouraging results but requires long tree ring and meteorological series to give robust results. We also highlight a risk of overfitting in the calibration of model parameters that increases with short series. Finally, MAIDEN has shown higher calibration and validation correlations in most cases compared to VS-Lite. Nevertheless, this latter model turns out to be more stable over calibration and validation periods. Our results provide a protocol for the application of MAIDEN to potentially any site with tree-ring width data in the extratropical region. [ABSTRACT FROM AUTHOR]

The retention of meltwater in the accumulation area of the Greenland ice sheet and other Arctic ice masses buffers their contribution to sea level change. However, sustained warming also results in impermeable ice layers or 'ice slabs' that seal the underlying pore space. Here, we use a 1-D, physically based, high-resolution model to simulate the surface mass balance (SMB), percolation, refreezing, ice layer formation and runoff from across the high-elevation area of Devon Ice Cap, Canada, from 2001 to 2016. We vary the thickness of the 'impermeable' ice layer at which underlying firn becomes inaccessible to meltwater. Thick near-surface ice layers are established by an initial deep percolation, the formation of decimetre ice layers and the infilling of interleaving pore space. The cumulative SMB increases by 48% by varying impermeable layer thickness between 0.01 and 5 m. Within this range we identify narrower range (0.25–1 m) that can simulate both the temporal variability in SMB and the observed near-surface density structure. Across this range, cumulative SMB variation is limited to 6% and 45–49% of mass retention takes place within the annually replenished snowpack. Our results indicate cooler summers after intense mid-2000s warming have led to a partial replenishment of pore space. [ABSTRACT FROM AUTHOR]

Copyright of Canadian Water Resources Journal / Revue Canadienne des Ressources Hydriques is the property of Taylor & Francis Ltd and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Canadian Journal of Statistics is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Canadian Journal of Economics is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The 13th International Conference on Advances in Quantitative Laryngology, Voice and Speech Research (AQL 2019) will be held in Montreal, Canada, 3–4 June 2019. Pre-conference workshops will be held on 2 June 2019. The conference and workshops provide a unique opportunity for partnership and collaboration in the advancement of quantitative methods for the measurement and modelling of voice and speech. The AQL accomplishes this mandate by facilitating an interprofessional scientific conference and training intended for an international community of otolaryngologists, speech–language pathologists and voice scientists. With a continued drive toward advancements in translational and clinical voice science, the AQL has rapidly expanded over the past 20 years, from a forum of 15 European member laboratories to a globally recognized symposium, connecting over 100 delegates from across the world. [ABSTRACT FROM AUTHOR]

We present δ60Ni values for black shales, determined by double-spike MC-ICP-MS. The samples comprise Paleoproterozoic Talvivaara Ni–Zn–Co–Cu black shales from Finland, Neoproterozoic black shales from the Teplá-Barrandian Unit, Czech Republic, Early Cambrian Ni–Mo-rich black shales from the Yangtze Craton, and Devonian Ni–Zn–PGE black shales from Yukon, Canada. In addition, the sample set includes a black smoker sample from the Logatchev hydrothermal field, Mid-Atlantic Ridge. The δ60Ni values vary from − 0.84 ± 0.09 to + 0.62 ± 0.04‰ (2SD) with a median of − 0.10‰ (n = 28). Ni isotopic compositions were predominantly lighter than those of abiotic terrestrial and extraterrestrial samples (0.15 and 0.27‰), mantle (0.23‰, Gall et al. 2017), present-day seawater (1.44‰, Cameron and Vance 2014), dissolved Ni from riverine input (0.84‰, Cameron and Vance 2014), ferromanganese crusts (0.9–2.5‰, Gall et al. 2013), Devonian/Mississippian organic-rich marine sediments, lower Jurassic organic-rich marine sediments (0.2–2.5‰, average 0.92‰, n = 18, Porter et al. 2014), and euxinic sediments of the Black Sea (0.14–0.51‰, Vance et al. 2016). However, the range of δ60Ni values in our black shale samples was close to that of the weathering products of mafic/ultramafic rocks (ore and soil samples) ranging from − 0.60 to + 0.30‰ (Ratié et al. 2015; Spivak-Birndorf et al. 2018), Ni-sulfide ores hosted by Archean komatiites from Australia and Canada (− 0.10 to − 1.03‰, average − 0.70‰, n = 8, Gueguen et al. 2013), and Archean Ni-rich magmatic sulfides from Zimbabwe (− 0.28 to − 0.47‰, n = 6, Hoffman et al. 2014). Based on our observations and considering the extremely low contribution of direct biological uptake of Ni, and a dominant Ni residence in early Fe/Ni-sulfides, we suggest that our mostly light Ni isotopic compositions in metal-rich black shales result from sulfidization of organic matter and Ni removal into sulfides. [ABSTRACT FROM AUTHOR]

Abstract: To analyze the production impacts of changes made in 2013 to Canada's AgriStability risk management program, we calibrate a crop allocation model using positive mathematical programming (PMP). Because PMP is not straightforward if farmers are assumed to maximize expected utility (as a risk parameter also needs to be calibrated), we consider possible ways to address this issue but settle on a traditional approach used in the EU's Farm System Simulator. We calibrate farm management models for six different Alberta regions and use it to determine how changes in the AgriStability's payment trigger affect production incentives. Results indicate that, although the initial introduction of the AgriStability program in 2008 might have tilted farmers’ planting decisions toward crops with higher returns and greater risk, changes to this program reduce indemnities and farmers’ expected profits, but do not further alter land‐use decisions. Rather, it is increases in farmers’ aversion to risk that lead to the greatest changes in crop allocation. [EconLit citations: Q14, Q18, C61]. [ABSTRACT FROM AUTHOR]

Copyright of Canadian Journal of Civil Engineering is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Background: In Canada, active tuberculosis (TB) disease rates remain disproportionately higher among the Indigenous population, especially among the Inuit in the north. We used mathematical modeling to evaluate how interventions might enhance existing TB control efforts in a region of Nunavut.Methods: We developed a stochastic, agent-based model of TB transmission that captured the unique household and community structure. Evaluated interventions included: (i) rapid treatment of active cases; (ii) rapid contact tracing; (iii) expanded screening programs for latent TB infection (LTBI); and (iv) reduced household density. The outcomes of interest were incident TB infections and total diagnosed active TB disease over a 10- year time period.Results: Model-projected incidence in the absence of additional interventions was highly variable (range: 33-369 cases) over 10 years. Compared to the 'no additional intervention' scenario, reducing the time between onset of active TB disease and initiation of treatment reduced both the number of new TB infections (47% reduction, relative risk of TB = 0.53) and diagnoses of active TB disease (19% reduction, relative risk of TB = 0.81). Expanding general population screening was also projected to reduce the burden of TB, although these findings were sensitive to assumptions around the relative amount of transmission occurring outside of households. Other potential interventions examined in the model (school-based screening, rapid contact tracing, and reduced household density) were found to have limited effectiveness.Conclusions: In a region of northern Canada experiencing a significant TB burden, more rapid treatment initiation in active TB cases was the most impactful intervention evaluated. Mathematical modeling can provide guidance for allocation of limited resources in a way that minimizes disease transmission and protects population health. [ABSTRACT FROM AUTHOR]

A series of time domain nonlinear and frequency domain equivalent-linear ground response analysis was conducted for a representative site in Ottawa, Canada. The objective is to provide insight into the performance of different site response analysis approaches in predicting site amplification factors for the soft soil deposit over a wide range of shear strain. The surficial geology of the site is predominantly composed of the sensitive Leda Clay typical of this region in eastern Canada. A combination of results and observations from monotonic and cyclic laboratory tests, as well as field geophysical experiments, was used to calibrate the dynamic properties of the Leda clay, more specifically, the variation of the clay's shear stiffness (G) with the in situ stress state ( $$\sigma_{vc}^{{\prime }} ,OCR$$ ). The calibrated relation was then successfully validated through material-specific site response analysis using the strong motion recordings from the 2010 Val-des-Bois earthquake and the shear wave velocity profile from borehole data. Comparison of the results with the hazard spectra proposed by NBCC 2010 reveals that the code-based site class E hazard spectra for the Ottawa area can be sufficient for seismic design, except around the natural site period. The results also suggest that the nonlinear analysis using the shear strength-adjusted hyperbola for modulus reduction and best-fitting trend to the laboratorybased damping would provide a reliable estimation of ground motion spectra at the natural site period. The performance of the ground response analysis alternatives for the sensitive clays, over a wide strain range was compared and discussed. [ABSTRACT FROM AUTHOR]

Building performance evaluations (BPEs) were carried out for nine Canadian green buildings using a standardised assessment framework. The aim was to explore and measure the discrepancies between the operational performance of the buildings and their predicted performance, as well as to identify lessons for their owners, design teams and the construction industry. The objective of this paper is not to report individual buildings in detail (we refer the reader to the individual building reports) but to report on some general lessons that came from doing this study. Overall these buildings performed well compared to benchmarks. However, the findings suggest that occupancy is not well understood and often incorrectly predicted during design, and that this affects various aspects of performance, including energy and water use. Also energy and water use modelling is often undertaken principally for building code/green rating compliance purposes and does not necessarily represent an accurate prediction of likely operational use. Combined with variations in occupancy this can lead to considerable discrepancies in performance from the modelled values. This may be understood by experts but is often misleading to building owners and others. Water use is often not well predicted and also not carefully managed in buildings and there is a lack of understanding of what constitutes good water performance. Overall, it is important to recognise that each building has its own individual "story" that provides necessary context for effective management and improvement of the building during its ongoing life. It is proposed that a BPE process allows that context to be better understood, and enables more effective decision making about building management, improvements, occupant satisfaction, energy use, etc. [ABSTRACT FROM AUTHOR]