To assess the North American high-latitude vegetation response to the rising temperature, we derived NDVI trend for 91.2% of the non-water, non-snow land area of Canada and Alaska using the ...peak-summer Landsat surface reflectance data of 1984–2012. Our analysis indicated that 29.4% and 2.9% of the land area of Canada and Alaska showed statistically significant positive (greening) and negative (browning) trends respectively, at significance level p<0.01, after burned forest areas were masked out. The area with greening trend dominated over that with browning trend for all land cover types. The greening occurred primarily in the tundra of western Alaska, along the north coast of Canada and in northeastern Canada; the most intensive and extensive greening occurred in Quebec and Labrador. The browning occurred mostly in the boreal forests of eastern Alaska. The Landsat-based greenness trend is broadly similar to the 8-km GIMMS AVHRR-based trend for all vegetation zones. However, for tundra, the Landsat data indicated much less extensive greening in Alaska North Slope and much more extensive greening in Quebec and Labrador, and substantially less extensive browning trend in the boreal forests that were free of fire disturbances. These differences call for further validation of the Landsat reflectance and the AVHRR NDVI datasets. Correlation study with local environmental factors, such as topography, glacial history and soil condition, will be needed to understand the heterogeneous greenness change at the Landsat scale.
•Discrepancy between Landsat 5 & 7 NDVI was corrected.•Wall-to-wall mapping of Landsat NDVI trend (1984–2012) across northern North America•Landsat data well capture the fire disturbances in boreal forests.•Landsat reveals more extensive greening in northeastern Canada compared to AVHRR.•But much less extensive greening in northern Alaska compared to AVHRR
An increasing number of studies since 2010 have examined bike sharing from diverse perspectives to provide the best travel practices of “the last mile”. However, few studies have attempted to ...comprehensively review existing literature over the past decade. The present study aims to map bike sharing research published between 2010 and 2018. A total of 208 relevant articles were collected to conduct scientometric analysis. The results revealed that the most significant contributions in bike sharing research primarily originated from the US, China, Canada, England and Australia. Critical institutions, publications and articles were also identified. The knowledge domains of bike sharing research focus mainly on topic categories of factors & barrier, system optimization, behavior & impact, safety & health, and sharing economy. Evolutionary trends in bike sharing research tend to move from the safety and benefits of bike usage to more complex external impacts, system optimization, design and integration with public transit. Furthermore, increasing interests and outputs in the new generation of dockless bike sharing programs were observed from the research community for the past two years. The present study contributes to the existing body of knowledge on bike sharing by presenting a new, integrated and holistic knowledge map. This study offers valuable guidance and in-depth understanding to researchers, operators and policy makers who wish to promote bike sharing sustainability, as well as for follow-up studies, updates and management.
•A scientometric review of 208 bike-sharing-related articles is conducted.•Key countries/regions and institutions, journals and articles are identified.•Keyword co-occurrence, timezone view and cluster analysis are used to help understand the overall research status.•As a result, a comprehensive knowledge map on bike sharing research is constructed.
Newcomers contribute to organizational innovation by bringing in new knowledge and ideas, on the one hand, and by collaborating and exchanging with incumbents, on the other. We propose that an ...organization's ability to use these contributions is influenced by hiring rate, hiring rate change, and hiring rate dispersion, which affect both the flow of new ideas into the organization and the level of collaboration between newcomers and incumbents. Using four years of data from a large, multi-industry sample, we find that hiring rate and hiring rate dispersion increase organizational innovation. We also find that increases in hiring rates from year to year are positively related to innovation for organizations with more collaborative work practices, while the relationship between hiring rate dispersion and innovation is less positive when organizations have more collaborative work practices. This study highlights how temporal patterns of hiring influence human capital acquisition and development.
The influence of human resource management on innovation has attracted considerable research attention over the last decade. However, existing studies have primarily focused on the macro-level human ...resource management architecture, limiting our understanding about the cross-level origin of innovation. Developing an emergence-based human resource management framework, we propose that an employee-experienced high-involvement work system (HIWS) promotes innovation by eliciting collective interactions for knowledge exchange and aggregation. Further, we investigate the emergence-enabling process that facilitates an employee-experienced HIWS to give rise to organization-level innovation. Specifically, we probe three distinct emergence enablers that amplify the positive influence of HIWS on innovation by shaping the concertedness, direction, and adaptability of collective interactions: (1) the homogeneity of HIWS experiences as the internal mechanism, (2) the strategic importance of innovation as the external mechanism, and (3) the churn in human resources as the temporal mechanism. We tested our theoretical model using data from a nationally representative sample of workplaces in Canada (n = 2,639). Our results suggest that an employee-experienced HIWS was positively related to innovation. In addition, this positive effect was amplified by all three emergence enablers (i.e., the homogeneity of HIWS experiences, the strategic importance of innovation, and the churn in human resources).
Coyotes (Canis latrans) are highly adaptable, medium-sized carnivores that now inhabit nearly every large city in the United States and Canada. To help understand how coyotes have adapted to living ...in urban environments, we compared two ecologically and evolutionarily important behavioral traits (i.e., bold-shy and exploration-avoidance behavior) in two contrasting environments (i.e., rural and urban). Boldness is an individual's reaction to a risky situation and exploration is an individual's willingness to explore novel situations. Our results from both tests indicate that urban coyotes are bolder and more exploratory than rural coyotes and that within both populations there are individuals that vary across both spectrums. Bolder behavior in urban coyotes emerged over several decades and we speculate on possible processes (e.g., learning and selection) and site differences that could be playing a role in this behavioral adaptation. We hypothesize that an important factor is how people treat coyotes; in the rural area coyotes were regularly persecuted whereas in the urban area coyotes were rarely persecuted and sometimes positively rewarded to be in close proximity of people. Negative consequences of this behavioral adaptation are coyotes that become bold enough to occasionally prey on pets or attack humans.
Methane emissions were measured at 6650 sites across six major oil and gas producing regions in Canada to examine regional emission trends, and to derive an inventory estimate for Canada's upstream ...oil and gas sector. Emissions varied by fluid type and geographic region, with the heavy oil region of Lloydminster ranking highest on both absolute and intensity-based scales. Emission intensities varied widely for natural gas production, where older, low-producing developments such as Medicine Hat, Alberta showed high emission intensities, and newer developments in Montney, British Columbia showed emission intensities that are amongst the lowest in North America. Overall, we estimate that the Canadian upstream oil and gas methane inventory is underestimated by a factor of 1.5, which is consistent with previous studies of individual regions.
•Models for predicting municipal solid waste (MSW) were developed.•Municipal level prediction was performed.•Socio-economic and demographic parameters were used.•Application of neural networks and ...decision tree algorithms were successful.•MSW generation was predicted with 16–23% prediction error.
The main objective of this study was to develop models for accurate prediction of municipal solid waste (MSW) generation and diversion based on demographic and socio-economic variables, with planned application of generating Canada-wide MSW inventories. Models were generated by mapping residential MSW quantities with socio-economic and demographic parameters of 220 municipalities in the province of Ontario, Canada. Two machine learning algorithms, namely decision trees and neural networks, were applied to build the models. Socio-economic variables were derived from Canadian Census data at regional and municipal levels. A data pre-processing and integration framework was developed in Matlab® computing software to generate datasets with sufficient data quantity and quality for modeling. Results showed that machine learning algorithms can be successfully used to generate waste models with good prediction performance. Neural network models had the best performance, describing 72% of variation in the data. The approach proposed in this study demonstrates the feasibility of creating tools that helps in regional waste planning by means of sourcing, pre-processing, integrating and modeling of publically available data from various sources.
The use of alternative fuels, particularly bio-based fuels, has been an important strategy to achieve greenhouse gas (GHG) emission reductions compared to petroleum-based fuels. However, ...discrepancies between results obtained by using different attributional life-cycle assessment (LCA) tools have challenged the credibility of the individual assessments, and as result, the progress towards or compliance with GHG mitigation targets. The objective of this study was to identify the main differences and commonalities in methodological structures, calculation procedures, and assumptions for the major commercial biofuel, ethanol, across three public LCA tools, BioGrace (EU), GHGenius (Canada), and GREET (U.S.), and a research-oriented fourth, the Virtual Sugarcane Biorefinery (VSB), a Brazilian platform for sugarcane ethanol assessments.
The calculated emissions across models ranged from 16 to 45 for sugarcane, 43–62 for corn, and 45–68 g CO2eq MJ−1 for wheat ethanol. Harmonizing the three public models with VSB assumptions for sugarcane ethanol produced in Brazil, the range was reduced to 16–17 g CO2eq MJ−1 for sugarcane ethanol. Agricultural production (e.g., N2O emissions from fertilizers; energy and fuel use; straw field-burning; and limestone application) and ethanol shipping were found to be the major causes for variations for differences calculated for sugarcane ethanol. Similarly, harmonizing BioGrace and GHGenius calculations using GREET assumptions for U.S. corn ethanol generated nearly identical results (models varied within a 3% range). The coproduct treatment method was found to be the most influential parameter in the variations calculated for both corn and wheat ethanol. The application of the tools as part of GHG emissions accounting requirements is often defined via regulations and differences and/or conflicting assumptions set-forth in these models lead to most differences observed. Our study provides recommendations for promoting transparency in LCA calculations and assumptions across the tools used in research and development or for regulatory tools regarding biofuels.
•Emissions ranged from 16 to 45 for sugarcane and 43–62 g CO2eq MJ−1 for corn ethanol.•LCA tools produce similar results when harmonized to the maximum possible extent.•Models are sensitive to methodology, which is a risk factor in policy arena.•We recommend strengthened efforts to strive for transparency in LCA.
•Local CO2 emission factors of China’s coal chemical products are published.•The total CO2 emission from China's coal chemical industry was 607 Mt in 2015.•The spatial disparity of CO2 emission from ...China's coal chemical industry is great.•CO2 emission from modern coal chemical industry is predicted to be 417 Mt in 2020.•Carbon capture, utilization, and storage has great potential to reduce its emission.
As the largest producer of coal chemical products in the world, China faces tremendous pressure to reduce its carbon emission. An accurate quantification of the carbon dioxide (CO2) emission of coal chemical industry in China is therefore necessary. However, due to the variety of coal chemical products and limitations of CO2 emission factors, the total CO2 emission of coal chemical industry has yet to be determined. In this study, local CO2 emission factors of coal chemical products in China are published based on first hand data from twenty-three coal chemical enterprises and the total CO2 emission of China's coal chemical industry is extrapolated. The provincial-level spatial distribution of the CO2 emission of coal chemical industry is presented to assist the government in identifying key emission reduction areas. Additionally, scenario analysis of CO2 emission for China’s modern coal chemical industry in 2020 is conducted to determine whether the development of the modern coal chemical industry will have a significant impact on future CO2 emission, as well as the effect of carbon capture, utilization and storage technologies on the reduction in carbon emission. The estimate shows that the total CO2 emission of the coal chemical industry in 2015 was 607 million tonnes (Mt), accounting for approximately 5.71% of China’s total CO2 emission. The figure is higher than the total annual CO2 emission of a country such as Canada (555 Mt) or Brazil (486 Mt). Quantifying the emission of the coal chemical industry is therefore critical to understand the global carbon budget. The spatial distribution shows that Shandong, Inner Mongolia and Shanxi release one-third of the coal chemical industry’s total CO2 emission. Considering the development of the modern coal chemical industry, its CO2 emission is predicted to be as high as 416.52 million tonnes in 2020. However, the CO2 emission could be reduced by 317.98 million tonnes when carbon capture, utilization and storage are applied to process and energy systems simultaneously. This paper quantifies the CO2 emission of the coal chemical industry in China for the first time, identifies key chemical products and the provinces in which they are produced, explores the carbon reduction potential by scenario analysis, and provides specific data to support the assessment of effective CO2 reduction policy.
We provide a framework for empirical analysis of negotiated-price markets. Using mortgage market data and a search and negotiation model, we characterize the welfare impact of search frictions and ...quantify the role of search costs and brand loyalty for market power. Search frictions reduce consumer surplus by $12/month/consumer, 28 percent of which can be associated with discrimination, 22 percent with inefficient matching, and 50 percent with search costs. Banks with large consumer bases have margins 70 percent higher than those with small consumer bases. The main source of this incumbency advantage is brand loyalty; however, price discrimination based on search frictions accounts for almost a third.
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