We studied correlation between crown conditions and tree-ring widths in 260 trees of pedunculate oak (Quercus robur L.) growing on 33 sites in southern Sweden. The tree-ring increment over 1998-2002 was highest in trees with healthy crowns, intermediate in trees with moderately declined crowns, and lowest in trees with heavily declining crowns. The time period with significant correlation between crown status and tree-ring increment varied between 10 years (given autocorrelation in tree-ring chronologies preserved) and 4 years (autocorrelation removed). In pairwise comparisons of three crown classes, differences in tree-ring increment between trees with healthy crowns and trees with heavily declining crowns were the most pronounced, Fisher LSD P value staying below 0.05 over 13 years (autocorrelation preserved ) or 4 years (autocorrelation removed). Over two 5-year periods (1993-1997 vs. 1998-2002) the cumulative increment increased significantly for trees with healthy crowns, did not change in trees with moderately declining crowns, and significantly decreased in trees with heavily declining crowns. For trees with healthy crowns, this dynamics may represent growth recovery after 1992 drought. Instead, oaks with defoliation above 60% appear to reach a threshold in their ability to recover growth. At sites on nutrient-poor soils cumulative increments over 1998-2002 differed significantly among trees with different crown condition and no differences were observed at sites on nutrient-rich soils. Analyses and interpretation of the oak growth trends as recovered from tree-ring chronologies may be improved by controlling for the crown status of the trees sampled, e.g., by using sampling strategy that would represent the average crown and growth conditions of the sites. 相似文献
Environmental Science and Pollution Research - Obesity and physical inactivity threaten human health, and both could be solved with exercise. However, a higher amount of pollutants is inhaled... 相似文献
The activity of fish monooxygenases has been extensively used as a monitoring tool to detect contamination of water bodies by cytochrome P450-inducing agents. In this study we evaluated the activities of ethoxy- (EROD), methoxy- (MROD) and pentoxy- (PROD) resorufin-O-dealkylases in the liver of Nile tilapias (Oreochromis niloticus) collected at the Guandu river, at a reference clean site (Lake 1) and at two other sampling sites (Lakes 2 and 3) in Rio de Janeiro state, Brazil. Alkoxyresorufin-O-dealkylases were measured fluorimetrically in the hepatic S9 fraction. EROD (17.7-fold), MROD (14.2-fold) as well as PROD activities were considerably higher in tilapias from Guandu river. A moderate increase of EROD (5.0-fold) and MROD (5.4-fold) was also found in tilapias from Lake 3. These findings suggest that Guandu river watershed, the main source of urban drinking water supply in Rio de Janeiro, is polluted with CYP1A-inducing xenobiotics. Furthermore, we also found a good linear relationship between EROD and MROD, a finding that agrees with the hypothesis that the two reactions are catalysed by the same CYP1A isoform in O. niloticus. 相似文献
Objective: The objective of this study was to discuss the challenges in estimating bicycle helmet effectiveness from case–control studies of injured cyclists and to estimate helmet effectiveness from cases and available exposure data.
Methods: Data were extracted from studies of cyclists in Seattle; Victoria and New South Wales, Australia; and The Netherlands. Estimates of helmet use were used as exposure to compute relative risks for Seattle and Victorian data. Cycling distance data are routinely collected in The Netherlands; however, these data cannot be disaggregated by helmet use, which makes it unsuitable for estimating helmet effectiveness. Alternative controls were identified from larger cohorts for the Seattle and New South Wales cases.
Results: Estimates of helmet effectiveness were similar from odds ratios (ORs) using hospital controls or from relative risks (RRs) using helmet use estimates (Seattle: OR = 0.339, RR = 0.444; Victoria: OR = 0.500, RR = 0.353). Additionally, the odds ratios using hospital controls were similar when controls were taken from a larger cohort for head injury of any severity (Seattle: OR = 0.250, alt OR = 0.257; NSW: OR = 0.446, alt OR = 0.411) and for serious head injury (Seattle: OR = 0.135, alt OR = 0.139; NSW: OR = 0.335, alt OR = 0.308). Although relevant exposure data were unavailable for The Netherlands, the odds ratio for helmet effectiveness of those using racing, mountain, or hybrid bikes was similar to other estimates (OR = 0.371).
Conclusions: Despite potential weaknesses with case–control study designs, the best available evidence suggests that helmet use is an effective measure of reducing cycling head injury. 相似文献
In the domain of environmental protection, multi-criteria evaluation is used in cases where multiple alternatives, on the
bases of multiple parameters, need to be evaluated. Depending on the particular goal of investigation, various approaches
have been developed and applied. This various multi-criteria approaches differ in parameter weighting method, in data normalization
method as well as in the method for assessment of alternatives. According to the applied multi-criteria methodology, the result,
i.e., the rank of alternatives may differ to some extent. In this context, parameter weighting bears special significance
in multi-criteria evaluation, while the choice of method is crucial for final result. The specificity of parameter weighting
process in environment protection is directly related to pronounced interdisciplinary character of this area, as well as the
large number of influential parameters. With this in mind, this paper presents an approach to multi-criteria evaluation which—through
integration of three specific methods for parameter weighting—allows more flexible and multi-purpose application. Based on
the established concept, a software application was developed. Besides automated parameter weighting, it also provides graphical
interpretation of results. The developed approach and software have been verified on the case study related to evaluation
of environmental loadings at six locations in the city of Novi Sad. 相似文献
The US government has focused considerable attention on enhancing our society’s ability to protect critical systems and services from disruptive events. Over the past decade, federal agencies have bolstered their efforts to identify and minimize threats using traditional risk-based approaches such as continuity of operations and disaster risk reduction processes. However, these valuable risk identification and management tools are limited because they rely upon foreseeable factor analyses of steady-state systems with predictable hazard frequencies and severities. In assessing the capability of complex adaptive systems to cope with disruptions, an overemphasis upon engineering resilience through risk management and planning for what is predictable may cloud or detract from our efforts to better understand a system’s emergent capabilities to withstand disruptions that are unforeseeable. This article contends that augmenting traditional risk approaches through the incorporation of methodologies grounded in socio-ecological system (SES) resilience principles offers a potential avenue for improving our agencies’ abilities to assess and manage both known and unknown risks. We offer a notional rationale for broadening our examination of system vulnerabilities and present a conceptual model that combines engineering and SES resilience paradigms to facilitate the identification, assessment, and management of system vulnerabilities. The Military Installation Resilience Assessment model described herein applies risk and resilience principles to evaluate whole systems, focusing on interconnections and their functionality in facilitating response and adaptation. 相似文献
Italy is a country highly vulnerable to floods and landslides. The present study aims to investigate disaster preparedness and perception of flood risk in a group of people living in an alpine valley in the north of Italy. Four hundred seven adult residents in nine communities exposed to hydrogeological risk were interviewed by using a structured questionnaire. Participants were asked about the adoption of a set of protective behaviors that can prevent negative consequences of floods. Perception of flood risk was assessed by means of a one-dimensional scale that was developed and validated by the authors. Items included in this scale asked participants to estimate likelihood of occurrence of different flood consequences and to express feelings of worry associated to them. Socio-demographic and experiential information on respondents were also collected. Overall, results showed that most of respondents were fairly well prepared to deal with a future flood disaster. Correlational and regression analyses indicated that disaster preparedness was positively associated with risk perception. In accordance with literature, there was not a significant relation between likelihood judgments and adoption of protective behaviors, while feelings of worry were associated with disaster preparedness. Authors interpret their results in relation to the socio-environmental characteristics of the studied communities. Theoretical, empirical and practical implications of the findings are also discussed. 相似文献