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Similar to many freshwater ecosystems, the Laurentian Great Lakes of North America have undergone numerous anthropogenic stressors resulting in considerable loss of biodiversity and habitat. Among Great Lakes fishes, the coregonine sub-family has endured the most extensive declines, including extinction of several species (Coregonus johannae, C. alpenae, and C. kiyi orientalis) and at least 10 instances of local extirpations of other species (C. nigripinnis, C. reighardi, C. zenithicus, C. hoyi, and C. artedi) across all 5 lakes, much of which occurred prior to the 1960s owing to overfishing, interactions with non-indigenous species, and habitat loss. Despite these declines, no federal-, provincial-, or state-mandated actions were ever implemented to conserve coregonine diversity, potentially because so much of the coregonine declines occurred prior to the enactment of federal conservation legislation. Possible explanations for inaction since enactment of that legislation include insufficient data on biological vulnerability or threats, unresolved taxonomy, and limited support from the fishery management agencies and their stakeholders prior to the 2000s. In recent decades, however, several fishery management agencies have undertaken efforts to re-introduce coregonine diversity. These efforts helped lead to development of a science-based framework to restore coregonines that was universally endorsed by fishery managers representing eight U.S. states, four U.S. tribal organizations, and the province of ON, Canada, in May 2018. The basin-wide framework is based on principles of conservation biology and adaptive management. We describe details of its key steps, including planning, restoring, and evaluating, while also describing recent implementation efforts to develop methods, improve available resources, and enhance coordination across the basin. Although our paper describes a regional effort to restore native coregonines, our adaptive-management approach could be used by other multi-agency stakeholders seeking to conserve or restore native fishes. [ABSTRACT FROM AUTHOR]

Forest succession is a dynamic process of progressive compositional development of ecological communities of species following natural or anthropogenic disturbance. Despite a rich history of conceptual frameworks, models, and empirical advances, the complex interactions among climatic conditions, disturbances, edaphic factors, and silvicultural treatments still challenge our ability to accurately predict forest succession, hindering application to forest management. Our goal was to improve understanding of forest succession in the managed boreal forests of North America by clarifying advances in knowledge and limitations in our understanding. We reviewed 152 peer-reviewed papers to: (i) document conceptual developments in forest succession; (ii) summarize drivers of North American boreal forest succession, including changes to forest composition and successional trajectories given climate change; and (iii) discuss the implications of the synthesized information for boreal forest management. While the element of stochasticity is expected to increase under climate change, successional dynamics are anticipated to remain predominantly deterministic. Southern boreal forests are at increased risk of mortality due to warming-driven drought and increased fires. Following disturbance, regeneration is likely to favor deciduous hardwoods. In boreal mixedwoods, increased fires would promote jack pine, and also black spruce on hydric and xeric sites. Dynamics of the northern boreal will depend on the balance between precipitation and evapotranspiration. Forest management must carefully select prescriptions to promote forest regeneration and composition that consider the long-term effects of changing climate and disturbance regimes. For instance, combining retention cut with mechanical site preparation would maintain site productivity and reverse open black spruce stand development in northern boreal stands. Our work shows that multiple disturbances have compounding effects on forest development, but further work is needed to better define thresholds for synergistic and buffering interactions. Modeling of boreal forest succession can be improved by incorporating more of the influential factors, but this is often limited by the lack of data. This information will guide the development of forest management strategies by exploring combinations of prescribed fire and variable intensity selection cutting systems to reproduce the effects of multiple interacting natural disturbances under climate change on successional dynamics. [ABSTRACT FROM AUTHOR]

In this paper, we examine the implications of managing for sustained yield in a world characterized by growing risk and uncertainty. We review the history of sustained yield (SY) forestry in North America, with an emphasis on economic benefits and the persistence of the SY paradigm today, despite a publicized shift towards managing for a wider range of forest values called sustainable forest management (SFM). We show that current forest management goals around sustainability as well as SFM indicators are still predicated on maximizing harvest levels and timber flows. We build a simple model to explore the implications of SY under extreme (fat-tailed) risk assumptions to show that maximizing a level of harvest without adequately accounting for risk leads towards the depletion of the forest stock with a corresponding decline in the forest economy. We discuss these results in relation to real-world events such as the increase in catastrophic fires and pest outbreaks like the mountain pine beetle in Western Canada. We then examine the theoretical and practical implications that flow from this model and analysis. [ABSTRACT FROM AUTHOR]

To address the transportation sector's contribution to climate change problems across North America (NA), passenger rail is an attractive solution. However, NA passenger rail traditionally relies on diesel motive power, which has been associated with causing health problems of noise, vibrations, and emissions. High costs of overhead and (or) third rail infrastructure have mostly precluded electrification. This paper examines the impact of battery size on fuel cell stack efficiency for hydrogen fuel cell – battery hybrid (hydrail) railway propulsion systems using dynamic simulations as opposed to existing simulations in the literature that rely on static efficiency values. The journey of the British Rail Class 156 diesel multiple unit is simulated over the round trip from Trehafod to Treherbert (UK) using a series hybrid architecture powertrain. Dynamic simulations at incremental battery masses were used to assess fuel cell efficiency, maximum power, and overall hydrogen consumption. Battery mass is employed as a proxy for power and energy capability of the battery. Results suggest that hydrail passenger railway systems work well, with hydrogen fuel cells handling most load dynamics. Hybridization with batteries works best and reduces fuel cell stack size and hydrogen consumption, with overall 64% stack efficiency. [ABSTRACT FROM AUTHOR]

Culverts are important components of highway infrastructure. They are structurally designed to support earth and live traffic loads. Corrugated steel pipes (CSPs) are widely used as culverts in North America in different geometries. However, due to the corrosive nature of the stormwater passing through the culverts, it is common to find CSPs with partially or entirely lost inverts. Dependent on site, depth of cover and embedment conditions, invert deterioration would not necessarily result in culvert failure. This paper presents the results of a laboratory testing campaign that evaluates the structural capacity of two circular CSPs and their equivalent arch CSP through the application of a vertical static loading. The circular pipe samples had a length of 6 ft (1.82 m) and a diameter of 60 in. (1.52 m). The same length arch pipe sample had a span of 71 in. (1.8 m) and a rise of 47 in. (1.19 m). The invert of the arch and one of the circular CSPs were cut to simulate heavily corroded culverts in service. The pipe samples were embedded under two feet (0.6 m) of cover using one foot (0.3 m) of sand and one foot (0.3 m) of coarse aggregates on top, simulating a base course layer of pavement. The results of testing showed that the invert-cut circular CSP was highly dependent on its ring stiffness. While, the invert-cut arch CSP took advantage of its arch geometry and was able to resist the applied load without significant loss in the sample pipe's horizontal dimension. [ABSTRACT FROM AUTHOR]

Freshwater unionid mussels are among the most imperiled fauna in North America, and their decline has been partially attributed to sediment from anthropogenic activities. However, there remains a debate regarding the role played by sediment in mussel declines due to a lack of field and laboratory evidence. If sediment is responsible for mussel declines, then a lack of information will likely impede efforts to mitigate species declines and protect remaining habitat. However, if the impacts of sediment are overstated, time and resources may be wasted on a threat that has little bearing on mussel declines or habitat loss. Given this knowledge gap, the purpose of this paper is to review the literature focused on the potential impact of suspended sediment and sedimentation on freshwater mussels. We focused our search on suspended sediment, expressed either as suspended sediment concentration (SSC) or total suspended solids (TSS), and sediment deposition and scour. We found increases in suspended solids could impact mussels by decreasing food availability, physically interfering with filter feeding and respiration, and impeding various aspects of the mussel–host relationship. We also found mussel–sediment thresholds, wherein certain concentrations of sediment caused significant declines in population performance, which could serve as reference points for ecological research and management. Specifically, we found clearance rates (a measure of feeding) were negatively impacted by TSS concentrations >8 mg/L, and respiratory stress occurred at ∼600 mg/L. Declines in fertilization success and glochidial (i.e., mussel larvae) development were observed at TSS values of 15 mg/L, and reproductive failure occurred at 20 mg/L. Impacts on host fish attachment and glochidial encystment occurred at TSS concentrations of 1250–5000 mg/L. Impacts on fish varied depending on the biological endpoint but typically occurred at TSS values ranging from 20 to 5000 mg/L. We also found mussels were sensitive to smothering and mortality occurred at depths as low as 0.6–2.5 cm of substrate. Finally, we found relative shear stress (RSS) values >1, which is a measure of substrate stability in response to scour and entrainment, resulted in significant declines in mussel biodiversity. [ABSTRACT FROM AUTHOR]

Resilient design requires information about a structure's response to a variety of exposures such that systems can be implemented to prevent unacceptable losses. For the case of critical infrastructure like bridges, losses associated with structural damage and traffic closures from fire events can be substantial. Despite this, there are no specific code requirements for bridge fire safety in different national jurisdictions, particularly in North America and Europe, and only minimal guidance available for establishing the fire resistance requirements of bridges. Research into the fire safety of bridges is ongoing but knowledge gaps persist that limit practitioners' ability to conduct performance-based fire designs using the latest state of existing research. This paper provides a first-stage state of the art review of bridge fire research conducted to date in effort to summarize key findings and make available the most relevant information for researcher and practitioner use. The key research themes considered as subdivisions are fire hazard and risk assessment, bridge fire scenario modelling, and the structural response of steel and composite steel-concrete, cable-supported, concrete, and fiber reinforced polymer bridges to fire. The authors conclude the study with identified knowledge gaps and priority research areas. [ABSTRACT FROM AUTHOR]

Dromiceiomimus brevitertius is a North American ornithomimid diagnosed primarily by the ratio of tibia length to femur length. It has recently, and perhaps incorrectly, been considered synonymous with Ornithomimus edmontonicus, with several authors questioning the utility of limb ratios in diagnosing taxa. While isolated ornithomimosaur material is common, specimens with sufficient diagnostic material to explore the question of synonymy are comparatively rare. The putative Dromiceiomimus specimen UALVP 16182 represents one of the few specimens in which diagnostic elements are available. It is therefore an important specimen for assessing the validity of Dromiceiomimus and for examining the utility of using limb proportions to diagnose ornithomimid taxa. In this paper, UALVP 16182 is described, the tibia/femur ratio is examined in closely related ornithomimid taxa, and the ratio is found to distinguish Dromiceiomimus from Gallimimus, Ornithomimus, and Struthiomimus. A phylogenetic analysis recovered Anserimimus and Ornithomimus as sister taxa with Dromiceiomimus as an outgroup. Comparison of the manus revealed differences in the morphology of metacarpal I and the flexor tubercle of manual ungual II-3. Differences also appear in the surangular and scapula. An examination of stratigraphic positions of various specimens indicates that Dromiceiomimus is generally higher in section than Ornithomimus, although there are too few specimens to be statistically significant. This study agrees with other studies in concluding that limb proportions are roughly isometric in small theropods like ornithomimids and that the tibia/femur ratio may therefore be useful for diagnosing certain small taxa. These findings suggest that Dromiceiomimus may indeed be a valid taxon. [ABSTRACT FROM AUTHOR]

Physiological performance in fish peaks within a well-defined range of temperatures, which is distinct for each species. Species-specific thermal responses for growth, survival, and reproduction are most commonly quantified directly through laboratory experiment or field observation, with a focus on six specific metrics: optimum growth temperature and final temperature preferendum (growth), upper incipient lethal temperature and critical thermal maximum (survival), and optimum spawning temperature and optimum egg development temperature (reproduction). These values remain unknown for many North American freshwater fish species. In this paper, we present a new statistical method (Bayesian phylogenetic regression) that uses relationships between these metrics and phenetic relatedness to estimate unknown metric values. The reliability of these estimates was compared with those derived from models incorporating taxonomic family and models without any taxonomic information. Overall, incorporating taxonomic family relatedness improved estimation accuracy across all metrics. For Salmonidae and Cyprinidae, estimates derived from Bayesian phylogenetic regression typically had the highest expected reliability. We used our methods to generate 274 estimates of unknown metric values for over 100 North American freshwater fish species. [ABSTRACT FROM AUTHOR]

The circumpolar boreal zone is one of the world’s major biogeoclimatic zones, covering much of North America and Eurasia with forests, woodlands, wetlands, and lakes. It regulates climate, acts as a reservoir for biological and genetic diversity, plays a key role in biogeochemical cycles, and provides renewable resources, habitat, and recreational opportunities. Poor agreement exists amongst scientists regarding this zone’s delimitation and the areal extent of boreal forests, even though the zone has been well-studied. This paper reviews the literature on the phytogeography of the zone and makes use of a geographic information system (GIS) and published maps to delineate a current map of the North American boreal zone and the hemiboreal subzone, which is a transitional area lying immediately to the south of the boreal zone that is usually included in the boreal zone by Europeans but excluded by North Americans. On the basis of the map described here, the boreal zone covers about 627 million ha, or 29% of the North American continent north of Mexico. If the hemiboreal subzone, at 116 million ha, is included, then 34% of the same area is covered. Forests and other wooded land (362 million ha) cover 58% of the North American boreal zone on the basis of current forest inventory data. With forests and other wooded land of the hemiboreal subzone (68 million ha) factored in, this percentage remains basically unchanged. Values reported in this paper are compared with other published statistics. Important sources of error contributing to differences in areal statistics are discussed. [ABSTRACT FROM AUTHOR]

This paper provides a brief history of the development of poplar research in Canada within the broader North American context, as background to the present collection of papers on current Canadian poplar research. After the earliest times and European settlement, a few individual scientists played a pioneering role in early selection and breeding of poplars. The development of farm shelterbelts in the prairies over the last 100 years, including the widespread distribution of adapted poplars, has had a significant impact on the landscape. In the last 30 years, industrial strategies for the development and use of poplars have been the most important driver for poplar research. All of these components have in some way foreshadowed the present dramatic leading-edge research in poplar genomics. With the increasing diversity and sophistication of poplar research, particularly in recent years, a need is seen for identification of research priorities and coordination of research activities by disparate parties. [ABSTRACT FROM AUTHOR]

Recent surveys have indicated that between 30% and 40% of all bridges in North America are in various states of deterioration. Funding is limited owing to the existence of other deficient components of the transportation infrastructure. It is clear, therefore, that the return on the available funding needs to be maximized. This paper presents a review of publications on cost optimization of concrete bridge components and systems and then continues with a review of the state-of-the-art in life-cycle cost (LCC) analysis and design of concrete bridges. The main objective of the paper is to encourage bridge engineers to move towards the increased use of advanced analysis and design optimization methods. [ABSTRACT FROM AUTHOR]

Novel ecosystems occur when new combinations of species appear within a particular biome. They typically result from direct human activity, environmental change, or the impacts of introduced species. In this paper, we argue that considering commercial tree plantations as novel ecosystems has the potential to help policy makers, resource managers, and conservation biologists better deal with the challenges and opportunities associated with managing plantations for multiple purposes at both the stand and landscape scales. We outline five inter-related issues associated with managing tree plantations, which are arguably the largest form of terrestrial novel ecosystem worldwide. This is to ensure that these areas contribute significantly to critical ecosystem services, including biodiversity conservation, in addition to their wood production role. We suggest that viewing tree plantations as novel socioecological systems may free managers from a narrow stand-based perspective and having to compare them with natural forest stands. This can help promote the development of management principles that better integrate plantations into the larger landscape so that their benefits are maximized and their potential negative ecological effects are minimized. [ABSTRACT FROM AUTHOR]

Incomplete knowledge of the ecological functions of small streams and their riparian zones, particularly their roles in larger watershed and landscape contexts, contributes to confusion and debate about the levels of riparian vegetation retention required along small streams for the purpose of protecting aquatic ecosystems, riparian wildlife, and water quality. As a consequence, there are marked differences in riparian forestry practices and management among jurisdictions throughout North America. To aid in resolving these issues, a symposium on small streams and their riparian zones was held at The University of British Columbia from 19 to 21 February 2002, which brought together scientists, managers, and practitioners and provided a forum for the presentation and discussion of emerging research results. This special issue includes a selection of papers presented at that symposium as well as one solicited paper. [ABSTRACT FROM AUTHOR]

This paper synthesizes information obtained from a comprehensive literature review and agency surveys on the state of the practice of fixed automated spray technology (FAST) systems. Experience with FAST systems in North America and Europe has revealed a mixed picture. On the one hand, several studies have indicated reductions in mobile operation costs and significant reductions in crash frequency, resulting in favorable benefit-cost ratios. On the other hand, there have been a variety of problems related to activation frequency, system maintenance and training. Installing a FAST system is complex and the challenges are often site specific. However, the evaluations cited show that FAST systems can be cost-beneficial if their locations are carefully chosen and if the system is supported with reliable environmental sensors. Finally, it was found that application of FAST systems in North America have recently increased. [ABSTRACT FROM AUTHOR]

Many hiking trails traverse the forests and public lands across North America. It has therefore become important for federal management to gain an understanding of total use on these trails. However, there has never been a formal attempt to estimate hiking on these long, backcountry trails. This paper presents an approach that utilizes two survey instruments (exit-site tallies and a trail-user questionnaire) and two primary estimation components (standard and augmented sites) to estimate hikers over a spatial and temporal span. For illustrative purposes, the methodology is applied to a 175 km segment of the Appalachian Trail from 1 June through 14 August 2007. Two alternative estimation methodologies are presented and compared. The model-based approach may be preferred to the design-based approach when sample size is small because it smoothes erratic strata estimates and yields smaller standard errors. However, the design-based approach relaxes an assumption and is more appropriate as sample size increases. In our survey of the Appalachian Trail, there was a 5.6% difference between the visitation estimates based on these two approaches, and such stability reinforces confidence in the methodology. [ABSTRACT FROM AUTHOR]

The clay plains of the Saint Lawrence Lowlands of eastern North America are subject to large landslides in sensitive clay. These landslides occur relatively infrequently, but can have very significant consequences. This type of risk (low frequency, high consequence) can be difficult to manage, as the return period is long enough that the most recent major event tends to be forgotten by the time the next major event occurs. This paper examines characteristics of large landslides in sensitive clay with the purpose of understanding the nature of the hazard, and this work is extended to develop a high level appreciation of risk to a network of linear infrastructure, using railways as an example. The analysis considers the characteristics of a number of large landslides documented in the literature, as well as statistical characteristics of a digital inventory of large landslides, including: surface area, debris travel distance, retrogression length, proximity to other landslides, crater shape, landslide mechanism, temporal frequency, and documented effects. A linear network with between 100 and 1000 river crossings in the sensitive clay deposits in eastern Canada is expected to suffer a major disruption once every 10 to 100 years. [ABSTRACT FROM AUTHOR]

Prediction of forest composition and structure over multiple generations of trees is often hampered by limited data on understory tree dynamics and the highly variable process of canopy recruitment in forest openings. In this paper, we describe a model of sapling dynamics and overstory recruitment for CANOPY, a spatially explicit, crown-based, individual-tree model of gap dynamics. The model incorporates gap size as a predictor of sapling recruitment and height growth, and it mimics the processes of sapling release, gap capture, and lateral gap closure. Calibration data were derived from 12 data sets with a wide range of stand ages and disturbance history in northern hardwood stands in the Great Lakes region, USA. The model accounted for 30%-62% of the variation in sapling density, composition, and growth rates. Predicted effects of increasing gap size on growth rate were similar to observed trends. Growth equations that included gap size as an independent variable generally gave better predictions of sapling density, species composition, and growth rates than equations based on conventional plot-level competition metrics. Long-term, 1000-year simulations produced estimates of stand basal areas and tree density in each size class that are close to the mean observed values for old-growth stands in the region. [ABSTRACT FROM AUTHOR]

Windstorms are common events in midlatitude west coast climates yet little is known about their long-term history and influence on regional forests. In this paper, we present a procedure that detects the timing and frequency of these high-wind events (HWEs) along the Pacific Northwest coast of North America using crossdated tree-ring measurements and detrended tree-ring chronologies derived from windsnapped trees. Our results show that abrupt changes in ring width patterns closely match dates of known HWEs and can serve as a nonclimatic basis for crossdating. Experimentation with different growth suppression and release criteria revealed that either a 50% decrease or a 50% increase in radial growth relative to the mean index value provided the best criterion for detecting windstorm-related growth anomalies. Comparing these results with the known occurrence of windstorms during the past century successfully identified all known major wind events during the study period. Low correlations between tree growth and climatic variables further imply that HWEs are the principal cause of interannual growth variations. Accordingly, we discuss the application of our procedure toward the development of a multicentury reconstruction of HWEs, a long-term analysis of decadal climate variability and HWEs, and the ecological role of HWEs in Pacific Northwest and other west coast forests. [ABSTRACT FROM AUTHOR]

The Fire and Fire Surrogates (FFS) network is composed of 12 forest sites that span the continental United States, all of which historically had frequent low-severity fire. The goal of the FFS study was to assess the efficacy of three management treatments (prescribed fire, mechanical thinning, and their combination) in reducing wildfire hazard and increasing ecosystem sustainability. This paper describes the impact of the FFS treatments on nitrogen (N) storage and distribution. At the network scale, total ecosystem N averaged 4480 kg·ha–1, with ~9% in vegetation, ~9% in forest floor, ~2% in deadwood, and ~80% in soil. The loss of vegetation N to fire averaged (±SE) 25 ±11 kg·ha–1, whereas the mechanical and combined mechanical and fire treatments resulted in N losses of 133 ±21 and 145 ±19 kg·ha–1, respectively. Western coniferous forests lost more N from each treatment than did eastern forests. None of the manipulative FFS treatments impacted >10%–15% of total N of these ecosystems. Management strategies that maximize ecosystem carbon (C) gain by minimizing loss of N should be a focus in western forests, where C and N cycling are tightly linked, but perhaps not in those eastern forests where atmospheric N deposition has decoupled C and N cycles. [ABSTRACT FROM AUTHOR]

Concrete pavements are well known for long structural life. The major challenge, however, is to provide a durable surface with adequate skid resistance for economy and safety. This paper examines the long-term frictional performance of eight different surface textures on 197 sections of concrete pavements within the long-term pavement performance (LTPP) program database. Analysis shows that tined and (or) grooved textures maintain consistently higher skid resistance over time and the surface friction of concrete pavements is less sensitive to ambient temperature. Cumulative traffic passes are more sensitive to longevity of friction than the cumulative axle loads. Five alternative models have also been successfully developed for prediction of the long-term skid resistance of concrete pavements as a function of texture type, cumulative traffic passes, speed, and concrete compressive strength. These models were shown to be statistically significant at 95% confidence levels with reasonable prediction accuracy. Les chaussées en béton sont reconnues pour leur longue durée de vie structurale. Le principal défi est toutefois de fournir une surface durable présentant une antidérapance adéquate pour la sécurité et l’économie. Le présent article examine le comportement au frottement de huit différentes textures de surface sur 197 sections de chaussées en béton dans la base de données du programme « long-term pavement performance (LTPP) ». L’analyse montre que des textures crantées et (ou) rainurées conservent de façon constante une meilleure antidérapance dans le temps et le frottement à la surface des chaussées en béton est moins sensible à la température ambiante. Le cumulatif des passages de la circulation est plus sensible à la longévité du frottement que le cumulatif des charges par essieu. Cinq autres modèles ont été développés avec succès pour prédire l’antidérapance à long terme des chaussées en béton en fonction du type de texture, du cumulatif des passages de la circulation, de la vitesse et de la résistance en compression du béton. Ces modèles se sont avérés statistiquement significatifs avec des coefficients de confiance de 95 % et une précision raisonnable de prévision. [ABSTRACT FROM AUTHOR]

Residential construction has changed little in decades. In North America, houses are constructed predominantly with cast-in-place (CIP) concrete basement foundations and “custom-built” wood platform - framing structures. To improve the productivity of residential construction, a precast concrete foundation (PCF) system was developed by the University of Alberta and its industrial partners. Although the PCF system can be built much faster and better than conventional CIP foundations, it has not been considered a viable alternative in residential construction due to the belief that it is costly and less flexible. To overcome this perception, special research efforts were made to address issues of manufacturability, constructability, and standardization. This paper proposes an innovative design of the PCF system that satisfies functional requirements, while obtaining a minimum total cost and achieving flexibility. The unique features include a modularized rib structure, external insulation, and simplified bolted connections. A comparative analysis between PCF and traditional CIP concrete foundation systems is also presented. [ABSTRACT FROM AUTHOR]

Ethnographic literature documents the pervasiveness of plant-management strategies, such as prescribed burning and other kinds of cultivation, among Northwest Peoples after European contact. In contrast, definitive evidence of precontact plant management has been elusive. Documenting the nature and extent of precontact plant-management strategies has relevance to historians, archaeologists, managers, conservationists, forest ecologists, and First Nations. In this paper, we summarize the various lines of evidence that have been, or could be, used to document ancient cultivation in the northwest of North America. We organize this discussion by the ecological consequences of ancient plant-management practices and their documented or potential visibility in the paleo-, neo-ecological, and archaeological records. Our review demonstrates that while finding evidence of ancient plant management can be difficult, such evidence can be found when innovative research methods are applied. Further, when various independent lines of evidence are compiled, reconstructions of past plant-management strategies are strengthened considerably. [ABSTRACT FROM AUTHOR]

In North America, the rapid movement away from the direct discharge of water treatment plant (WTP) residual streams to receiving environments has resulted in considerable benefits to the drinking water industry in terms of enhancing environmental stewardship practices and supporting source water protection strategies. Over the past 20 years, application based research on appropriate technologies to treat residual streams such as filter backwash water (FBWW) has promoted the development of integrated process design that presents recycling as a viable residual management option. However, as utilities continue to develop and expand their main process lines to comply with more stringent government regulations encompassing both water quality and residual disposal practices, the development of sustainable residual management practices is expected to become a more prominent issue for this industry. The purpose of this paper is to present, from a critical point of view, the matrix of issues that currently exist regarding WTP residual streams and strategic pathways that would enhance future decision making processes for achieving long-term residual management solutions for the drinking water industry. En Amérique du Nord, l’abandon rapide de la décharge directe des effluents des usines de traitement des eaux dans les milieux récepteurs a grandement profité à l’industrie de l’eau potable en termes d’amélioration des pratiques de gérance environnementale et de soutien des stratégies de protection des sources d’eau. La recherche des 20 dernières années, appliquée aux technologies appropriées de traiter les effluents, tels que l’eau de lavage des filtres à contre-courant, a favorisé le développement d’une conception de procédé intégrée qui présente le recyclage comme une option viable de gestion des matières résiduelles. Toutefois, à mesure que les services publics continuent de développer et d’étendre leurs chaînes de procédé principales pour rencontrer les règlements gouvernementaux plus sévères touchant la qualité des eaux et les pratiques d’élimination des matières résiduelles, le développement de pratiques de gestion durable des matières résiduelles devrait revêtir plus d’importance pour cette industrie. L’objectif de cet article est de présenter de manière critique la matrice des enjeux existants dans les effluents des usines de traitement des eaux et les chemins stratégiques qui pourraient améliorer les prises de décisions futures pour arriver à des solutions de gestion des matières résiduelles à long terme pour l’industrie de l’eau potable. [ABSTRACT FROM AUTHOR]

The Dietary Reference Intakes (DRIs) are the North American reference standards for nutrients in the diets of healthy individuals. The macronutrient DRI report includes the standards for energy, fat and fatty acids, carbohydrate and fiber, and protein and amino acids. Equations used to identify the Estimated Energy Requirement (EER) were also developed based on individual characteristics including levels of physical activity. The DRIs for the macronutrients are presented as Recommended Dietary Allowances (RDAs) or Adequate Intakes (AIs), as well as Acceptable Macronutrient Distribution Ranges (AMDRs), and were arrived at by considering both nutrient inadequacies and excesses. In addition, recommendations are made that would reduce the risk of chronic diseases, such as setting intake limits for added sugar; reducing cholesterol, saturated, and trans fatty acids consumption; and increasing levels of physical activity. As healthy individuals include those engaged in various levels of physical activity, the DRIs should apply to the athlete and address their macronutrient and energy needs. This paper summarizes the macronutrient DRI report as applied to the adult, with discussion of the dietary needs of those engaged in various levels of physical activity, including the athlete. [ABSTRACT FROM AUTHOR]

The North American Central Plains (NACP) anomaly in enhanced electric conductivity and its relationship with the Paleoproterozoic Trans-Hudson orogen (THO) has been studied under the auspices of Lithoprobe for over a decade. The NACP anomaly was the first geophysical evidence of the existence of the THO beneath the Phanerozoic sediments of the Central Plains. This anomaly, detected geomagnetically in the late 1960s, has been the subject of a number magnetotelluric studies from the early 1980s. The PanCanadian and Geological Survey of Canada experiments in the 1980s and the Lithoprobe experiments in the 1990s together comprise four east–west and one north–south regional-scale profiles in Saskatchewan perpendicular to the strike of the orogen. In this paper, data from the northernmost line, coincident with seismic line S2B, are analysed and interpreted, and are shown to be key in determining the northern extension of the NACP anomaly. Dimensionality analysis confirms the rotation of deep crustal structures eastward to Hudson Bay, as earlier proposed on the basis of broad-scale geomagnetic studies. On this profile, as with the profile at the edge of the Paleozoic sediments, the NACP anomaly is imaged as lying within the La Ronge domain, in contact with the Rottenstone domain, and structurally above the Guncoat thrust, a late compressional feature. The location of the anomaly together with the surface geology suggests that the anomaly is caused either by sulphide mineralization concentrated in the hinges of folds, by graphite, or by a combination of both. Our interpretation of the data is consistent with that from other profiles, and suggests that the NACP anomaly was formed as a consequence of subduction and collisional processes involving northward subduction of the internides of the THO beneath the Hearne craton. On the southern part of this profile, a resistive structure is identified as the Sask craton, suggesting that Proterozoic rocks are above Archean rocks in the THO. [ABSTRACT FROM AUTHOR]

Sudden dieback and deterioration of mature aspen stands is commonly observed throughout North America. This dieback process has tremendous ecological and economic importance, yet remains poorly understood. This paper summarizes our understanding of aspen dieback in North America, identifies potential processes that contribute to reduced vigour and dieback of aspen stands, and examines the scales (stand, ecosite, regional) at which these processes operate. Many factors including pathogens, nutrition, or successional changes may be involved in the decline of aspen vigour and thereby contribute to the dieback process. However, insect defoliation, drought, and thaw–freeze events appear to be the most likely factors initiating dieback in mature aspen stands. Further study is clearly needed to elucidate the mechanisms and landscape patterns of dieback. Information needs related to identifying processes and modeling landscape patterns of dieback are indicated. [ABSTRACT FROM AUTHOR]

Road and highway maintenance is vital for the safety of citizens and for enabling emergency and security services to perform their essential functions. Accumulation of snow and (or) ice on the pavement surface during the wintertime substantially increases the risk of road crashes and can have negative impact on the economy of the region. Recently, road maintenance engineers have used pavement surface temperature as a guide to the application of deicers. Stations for road weather information systems (RWIS) have been installed across Europe and North America to collect data that can be used to predict weather conditions such as air temperature. Modelling pavement surface temperature as a function of such weather conditions (air temperature, dew point, relative humidity, and wind speed) can provide an additional component that is essential for winter maintenance operations. This paper uses data collected by RWIS stations at the City of Ottawa to device a procedure that maximizes the use of a data batch containing complete, partially complete, and unusable data and to study the relationship between the pavement surface temperature and weather variables. Statistical models were developed, where stepwise regression was first applied to eliminate those variables whose estimated coefficients are not statistically significant. The remaining variables were further examined according to their contribution to the criterion of best fit and their physical relationships to each other to eliminate multicollinearities. The models were further corrected for the autocorrelation in their error structures. The final version of the developed models may then be used as a part of the decision-making process for winter maintenance operations. [ABSTRACT FROM AUTHOR]

The condition of sewer pipes in North America has severely deteriorated, over the last few decades, creating a need for rehabilitation. Sewer rehabilitation methods are numerous and are constantly being developed, benefiting from emerging technologies. The implementation of these methods is driven by the need to improve quality and to reduce cost and project duration. One of the rapidly expanding fields in the sewer rehabilitation industry is trenchless technology. Due to the large number of methods associated with emerging new technologies in this field, selecting the most suitable method can be a challenging task. Selection in this environment, without a computerized tool, may also suffer from the limited knowledge and (or) experience of the decision-maker and could result in overlooking some of the suitable methods that could do the job at less cost. This paper describes a recently developed system for rehabilitation of concrete and clay sewer pipes and focuses primarily on two of its components: (i) the database management system (DBMS) and (ii) the decision support system (DSS). The system can assist municipal engineers and contractors in selecting the most suitable trenchless rehabilitation technique that specifies job conditions and user requirements. An example application is presented to demonstrate the use and capabilities of the developed system.Key words: pipe defects, rehabilitation, sewer pipes, database management systems, decision support systems, multi-attribute utility theory.Les conditions des conduites d'égout en Amérique du Nord se sont déteriorées sévèrement durant les dernières décennies, créant un besoin pour une remise en état. Les méthodes de remise en état de systèmes d'égout sont nombreuses et en développement constant, bénéficiant de technologies émergentes. L'utilisation de ces méthodes est motivée par le besoin d'améliorer la qualité, la réduction des coûts et la durée du projet. Un des domaines en expansion rapide dans l'industrie de la remise en état de systèmes d'égout est la technologie sans tranchée. À cause du large nombre de méthodes associées aux nouvelles technologies émergentes dans ce domaine, la sélection de la méthode la plus appropriée peut être une tâche difficile. La sélection dans cet environnement, sans outil informatique, peut aussi souffrir des connaissances et/ou expériences limitées du preneur de décisions, et peut conduire à l'omission de méthodes appropriées qui pourraient accomplir le travail à moindre coût. Cet article décrit un système récemment développé pour la remise en état de conduites d'égout en béton et en argile, et se concentre principalement sur deux de ses composantes: (i) le système de gestion de bases de données « database management system (DBMS) » et (ii) le système d'aide à la décision « decision support system (DSS) ». Le système peut assister les ingénieurs municipaux et les contracteurs dans la sélection de la technique de remise en état sans tranchée la plus appropriée selon les conditions de travail et les exigences de l'usager. Un example d'application est présenté afin de démontrer l'usage et les capacités du système développé.Mots clés : défauts de conduites, remise en état, conduites d'égout, système de gestion de bases de données, système d'aide à la décision, theorie de services à attributs multiples.[Traduit par la Rédaction] [ABSTRACT FROM AUTHOR]