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81.
Trends of summer precipitation and summer temperature and their influence on trends in summer drought and area burned in British Columbia (BC) were investigated for the period 1920–2000. The complexity imposed by topography was taken into account by incorporating high spatial resolution climate and fire data. Considerable regional variation in trends and in climate–fire relationships was observed. A weak but significant increase in summer temperature was detected in northeastern and coastal BC, whereas summer precipitation increased significantly in all regions—by up to 45.9 %. A significant decrease in province-wide area burned and at the level of sub-units was strongly related to increasing precipitation, more so than to changing temperature or drought severity. A stronger dependence of area burned on precipitation, a variable difficult to predict, implies that projected changes in future area burned in this region may yield higher uncertainties than in regions where temperature is predominantly the limiting factor for fire activity. We argue that analyses of fire–climate relationships must be undertaken at a sufficiently high resolution such that spatial variability in limiting factors on area burned like precipitation, temperature, and drought is captured within units.  相似文献   
82.
Coe KK  Belnap J  Sparks JP 《Ecology》2012,93(7):1626-1636
Precipitation patterns including the magnitude, timing, and seasonality of rainfall are predicted to undergo substantial alterations in arid regions in the future, and desert organisms may be more responsive to such changes than to shifts in only mean annual rainfall. Soil biocrust communities (consisting of cyanobacteria, lichen, and mosses) are ubiquitous to desert ecosystems, play an array of ecological roles, and display a strong sensitivity to environmental changes. Crust mosses are particularly responsive to changes in precipitation and exhibit rapid declines in biomass and mortality following the addition of small rainfall events. Further, loss of the moss component in biocrusts leads to declines in crust structure and function. In this study, we sought to understand the physiological responses of the widespread and often dominant biocrust moss Syntrichia caninervis to alterations in rainfall. Moss samples were collected during all four seasons and exposed to two rainfall event sizes and three desiccation period (DP) lengths. A carbon balance approach based on single precipitation events was used to define the carbon gain or loss during a particular hydration period. Rainfall event size was the strongest predictor of carbon balance, and the largest carbon gains were associated with the largest precipitation events. In contrast, small precipitation events resulted in carbon deficits for S. caninervis. Increasing the length of the DP prior to an event resulted in reductions in carbon balance, probably because of the increased energetic cost of hydration following more intense bouts of desiccation. The season of collection (i.e., physiological status of the moss) modulated these responses, and the effects of DP and rainfall on carbon balance were different in magnitude (and often in sign) for different seasons. In particular, S. caninervis displayed higher carbon balances in the winter than in the summer, even for events of identical size. Overall, our results suggest that annual carbon balance and survivorship in biocrust mosses are largely driven by precipitation, and because of the role mosses play in biocrusts, changes in intra-annual precipitation patterns can have implications for hydrology, soil stability, and nutrient cycling in dryland systems.  相似文献   
83.
This article proposes a hierarchical multivariate conditional autoregressive model applied to a compositional response vector. We particularly focus on situations when the composition is discrete occurring when observations are based on small multinomial counts. We address drawbacks that exist in current modeling approaches for such data. Our hierarchical model will be demonstrated with data used to help manage a commercial sockeye salmon fishery in the Fraser River of British Columbia.  相似文献   
84.
Aim and Background Currently, the protection from hazardous substances occurring in consumer articles is often insufficient. In this paper, we discuss whether this situation will improve relevantly in the course of the implementation of the new European regulation on chemical substances (REACH). Changes under REACH may be heterogeneous. Therefore, differential effects depending on the tonnage as placed on the market, on the amount of substances contained in an article, and depending on timelines and exemptions for meeting the legal requirements, are discussed in this paper, together with a presentation of some uses of substances serving as examples. Discussion and Conclusions If substances are adequately registered, all identified and supported uses including their use in articles should be assessed. Therefore, where the full implementation of the registration conditions applies a substantial improvement may be expected due to REACH. Usually, producers or importers of articles are not required to register substances contained in these articles. Instead, the manufacturer or importer of the respective substance is usually responsible for registration, if exposure to the substance cannot be excluded and emission of the substance from an article is not the intended purpose. This may differ for substances intentionally released from articles. Additional obligations for substances not intentionally released mainly apply to substances of very high concern (SVHC). For the latter, the producer or importer of articles has to notify the European Chemicals Agency (ECHA) on the occurrence of the respective SVHC in articles. This information is important, especially because substances in imported articles may not be registered in advance. Authorisation within REACH is a very far reaching and effective tool of the legislation. However, authorisation is not required for SVHC imported as components of articles. Therefore, one main effect intended by REACH, i.?e. the substitution of SVHC, may possibly be undermined by importers of SVHC in articles. Restrictions, as specified in Annex XVII of REACH, offer a powerful opportunity to improve health and environmental safety with respect to hazardous substances. We support an extended understanding of what is defined as a “substance of concern” in the context of restrictions. This definition should be broader than just what is currently covered by the term SVHC. Consequences of restrictions may equally apply to European producers and importers of articles from outside of Europe, which contain such substances of concern. Another instrument currently closely linked to SVHC (in its more restricted definition), is the obligation of the producer or importer of articles to provide information according to article 33 (REACH). The downstream recipient of an article has to be informed on the content of SVHC in this article and how its safe use is ensured. Warehouses, wholesalers and other traders may therefore be aware of the SVHC contained in articles and may look for substitutes without such ingredients. Also, consumers may request this information on SVHC (just provided on demand) and are thus enabled to decide to buy other articles with less hazardous properties.  相似文献   
85.
Experiencing uncivil customers is a frequent reality for many people working in the service industry. Past research has established that dealing with uncivil customers can be distressing for employees and can sometimes lead them to engage in reciprocal, discourteous behavior. The purpose of our research is to delve deeper into the experience of customer incivility from the perspective of service employees in order to better understand the various ways in which they respond to customer incivility. We conducted 64 interviews with service employees across an array of occupations and developed a typology of responses to customer incivility. These responses fell into four categories based on the extent to which service employees' actions were intended to promote social harmony (and therefore could broadly be considered civil or uncivil), as well as their perceived agency in the situation. We describe how each response was associated with different interpersonal and intrapersonal consequences and explain the implications of our typology for management theory and practice.  相似文献   
86.
The paper addresses the wear particles released from commercially available “low-metallic” automotive brake pads subjected to brake dynamometer tests. Particle size distribution was measured in situ and the generated particles were collected. The collected fractions and the original bulk material were analyzed using several chemical and microscopic techniques. The experiments demonstrated that airborne wear particles with sizes between 10 nm and 20 μm were released into the air. The numbers of nanoparticles (<100 nm) were by three orders of magnitude larger when compared to the microparticles. A significant release of nanoparticles was measured when the average temperature of the rotor reached 300 °C, the combustion initiation temperature of organics present in brakes. In contrast to particle size distribution data, the microscopic analysis revealed the presence of nanoparticles, mostly in the form of agglomerates, in all captured fractions. The majority of elements present in the bulk material were also detected in the ultra-fine fraction of the wear particles.  相似文献   
87.
The group of elements known as the rare earth elements (REEs) is comprised of the 15 lanthanides. REEs are used in a number of technologies including catalysts for automobiles and petroleum refining, magnets for wind turbines and defense technologies, and phosphors in lighting and computer and TV screens. REEs are actually quite abundant in the earth′s crust. The elements are deemed “rare” because they are found in low concentrations and are difficult to extract economically. China holds 48% of the global REE reserves, and until 2012, production of REEs was almost exclusive to China. Over the past decade, China has been steadily decreasing its REE export quotas, reducing the supply of REEs available to the rest of the world. REEs are considered critical materials according to the National Science and Technology Council, which defines critical elements as those serving an essential function in the manufacture of a product, the absence of which would cause significant social consequence. Thus, it is extremely important for consumers of REEs to be aware of and understand the risks facing the supply REEs, as awareness is the first and most important step in developing strategies to mitigate risk. This report presents a mechanism for identifying the risks present in a supply–demand scenario and determining the criticality of an individual rare earth element under specific circumstances.  相似文献   
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