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31.
A. H. Fullerton D. Jensen E. A. Steel D. Miller P. McElhany 《Environmental Modeling and Assessment》2010,15(1):13-26
Complex relationships between landscape and aquatic habitat conditions and salmon (Oncorhynchus spp.) populations make science-based management decisions both difficult and essential. Due to a paucity of empirical data,
models characterizing these relationships are often used to forecast future conditions. We evaluated uncertainties in a suite
of models that predict possible future habitat conditions and fish responses in the Lewis River Basin, Washington, USA. We
evaluated sensitivities of predictions to uncertainty in model parameters. Results were sensitive to 60% of model parameters
but substantially so (|partial regression coefficients| >0.5) to <10%. We also estimated accuracy of several predictions using
field surveys. Observations mostly fell within predicted ranges for riparian shade and fine-sediment deposition, but large
woody debris estimates matched only half the time. We provide suggestions to modelers for improving model accountability,
and describe how managers can incorporate prediction uncertainty into decision-making, thereby improving the odds of successful
salmon habitat recovery. 相似文献
32.
Debbie Eraly Frederik Hendrickx Lieven Bervoets 《Environmental pollution (Barking, Essex : 1987)》2010,158(6):2124-2131
Both local adaptation and acclimation in tolerance mechanisms may allow populations to persist under metal pollution. However, both mechanisms are presumed to incur (energetic) costs and to trade-off with other life-history traits. To test this hypothesis, we exposed Pardosa saltans (Lycosidae) spiderlings originating from metal-polluted and unpolluted sites to a controlled cadmium (Cd) treatment, and compared contents of metal-binding metallothionein-like proteins (MTLPs), internal metal concentrations, and individual survival and growth rates with a reference treatment. While increased MTLP concentrations in offspring originating from both polluted and unpolluted populations upon exposure indicates a plastic tolerance mechanism, survival and growth rates remain largely unaffected, independent of the population of origin. However, MTLP and Cd concentrations were not significantly correlated. We suggest that MTLP production may be an important mechanism enabling P. saltans populations to persist in ecosystems polluted with heavy metals above a certain level. 相似文献
33.
Anthony E. Held Daniel P.Y. Chang Debbie A. Niemeier 《Journal of the Air & Waste Management Association (1995)》2013,63(1):121-132
ABSTRACT A series of twelve intensively monitored 1-hr CO dispersion studies were conducted near Davis, CA, in winter 1996. The experimental equipment included twelve CO sampling ports at elevations up to 50 m, three sonic anemometers, a tethersonde station, aircraft measurements of wind and temperature profile aloft, and a variety of conventional meteorological equipment. The study was designed to explore the role of vehicular exhaust buoyancy during worst-case meteorological conditions, such as low winds oriented in near-parallel alignment with the road during a surface-based nocturnal inversion. From the study, field estimates of the CO emission factor (EF) from a California vehicle fleet were computed using two different methods. The analysis suggests that the CT-EMFAC/ EMFAC (EMission FACtor) models currently used to conduct federal conformity modeling significantly overpredict CO emissions for high-speed, free-flowing traffic on California highways. 相似文献
34.
此文对T10钢经线切割加工的开裂模具进行了金相分析、应力分析和断裂分析,从而提出了减少变形和开裂的措施。列举了生产实例,供模具制造者参考。 相似文献
35.
Steel E. Ashley Kelsey Kathryn A. Morita June 《Environmental and Ecological Statistics》2004,11(1):21-29
The Truth About Science is a 40-lesson middle school curriculum module that teaches the process of scientific research, integrating mathematics and science concepts and skills. The goal of the curriculum is to teach students to think systematically and statistically about science inquiry. Students participate in each step of the scientific inquiry process, from asking testable research questions, designing unbiased experiments, and collecting their own data, to analyzing these data via graphical representations and statistical summaries, and communicating their research results as both poster and oral presentations. While the necessary statistical skills depend on difficult and abstract mathematical concepts, middle school students have been successful in applying them to their own research projects. The curriculum meets local and national standards in science and mathematics education and fills a gap in available educational materials. It has been piloted and revised through multiple iterations and published by the National Science Teachers Association Press. Feedback from teachers and students has been extremely positive. 相似文献
36.
Random denominators and the analysis of ratio data 总被引:2,自引:0,他引:2
Liermann Martin Steel Ashley Rosing Michael Guttorp Peter 《Environmental and Ecological Statistics》2004,11(1):55-71
Ratio data, observations in which one random value is divided by another random value, present unique analytical challenges. The best statistical technique varies depending on the unit on which the inference is based. We present three environmental case studies where ratios are used to compare two groups, and we provide three parametric models from which to simulate ratio data. The models describe situations in which (1) the numerator variance and mean are proportional to the denominator, (2) the numerator mean is proportional to the denominator but its variance is proportional to a quadratic function of the denominator and (3) the numerator and denominator are independent. We compared standard approaches for drawing inference about differences between two distributions of ratios: t-tests, t-tests with transformations, permutation tests, the Wilcoxon rank test, and ANCOVA-based tests. Comparisons between tests were based both on achieving the specified alpha-level and on statistical power. The tests performed comparably with a few notable exceptions. We developed simple guidelines for choosing a test based on the unit of inference and relationship between the numerator and denominator. 相似文献
37.
Perceived safety from crime in the urban environment 总被引:1,自引:0,他引:1
Two studies were conducted to test various aspects of Appleton's Prospect-Refuge Theory. Hypotheses derived from the theory predicted that observers would rate how safe from crime they would feel in specific urban environments on the basis of whether the environments offered visibility (light), prospect (open spaces) and unambiguous refuge (a place where a criminal would not see the intended victim, or where other, non-threatening people were likely to to be present). It was further hypothesized that women in general would feel less safe from crime than men. In Study 1, University students generated lists of environmental features relevant to safety. Light was the most frequently mentioned factor, followed by open space and unambiguous refuge. In Study 2, slides were presented in which these three characteristics were independently varied. The results supported all of the hypotheses. 相似文献
38.
39.
Amy C. Dolan Michael T. Murphy Lucas J. Redmond Debbie Duffield 《Behavioral ecology and sociobiology》2009,63(10):1527-1537
Sex allocation theory predicts that if variance in reproductive success differs between the sexes, females who are able to
produce high-quality young should bias offspring sex ratio towards the sex with the higher potential reproductive success.
We tested the hypothesis that high-quality (i.e., heavy) female eastern kingbirds (Tyrannus tyrannus) that bred early in the breeding season would produce male-biased clutches. A significant opportunity for sexual selection
also exists in this socially monogamous but cryptically polygamous species, and we predicted that successful extra-pair (EP)
sires would be associated with an excess of male offspring. Although population brood sex ratio did not differ from parity,
it increased significantly with female body mass and declined with female breeding date, but was independent of the morphology
and display (song) behavior (correlates of reproductive success) of social males and EP sires. Male offspring were significantly
heavier than female offspring at fledging. Moreover, the probability that male offspring were resighted in subsequent years
declined with breeding date, and was greater in replacement clutches, but lower when clutch size was large. Probability of
resighting female offspring varied annually, but was independent of all other variables. Given that variance in reproductive
success of male kingbirds is much greater than that of females, and that male offspring are more expensive to produce and
have a higher probability of recruitment if fledged early in the season, our results support predictions of sex allocation
theory: high-quality (heavy) females breeding when conditions were optimal for male recruitment produced an excess of sons. 相似文献
40.