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81.
John A. Robertson Alex W. Thomas Julien Modolo Jodi Miller Nicole Juen Alexandre Legros Frank S. Prato 《The Environmentalist》2011,31(2):134-139
The field of bioelectromagnetics, consisting of the study of the interaction between electromagnetic fields and biological
systems, has been rapidly expanding in the recent years. One important factor that contributes importantly to the development
of this field is the continuing advances in technology allowing researchers to investigate different endpoints, or to more
precisely measure changes, if any. Hybrid functional imaging is a rapidly maturing field that opens new, important horizons
for bioelectromagnetics research. Indeed, unraveling the interaction mechanisms of electromagnetic fields on biological systems
(with an emphasis on the brain) requires a monitoring of electrical, functional, and metabolic activity of living tissue at
different temporal and spatial scales. Individual tools (e.g., electroencephalography, EEG; functional magnetic resonance
imaging, fMRI) are limited in their ability to detect the effects of electromagnetic interaction at specific temporal and
spatial scales, so combining these imaging methods offers a unique opportunity to provide a more comprehensive view of effects
in living tissue. In this paper, we will present the different imaging techniques that are available to bioelectromagnetics
researchers, including their capabilities and how they are complemented by simultaneous hybrid imaging. Future possibilities
of hybrid imaging technologies are discussed. 相似文献
82.
Road-killed mammals, birds, and reptiles were collected weekly from highways in southern Brazil in 2002 and 2005. The objective
was to assess variation in estimates of road-kill impacts on species richness produced by different sampling efforts, and
to provide information to aid in the experimental design of future sampling. Richness observed in weekly samples was compared
with sampling for different periods. In each period, the list of road-killed species was evaluated based on estimates the
community structure derived from weekly samplings, and by the presence of the ten species most subject to road mortality,
and also of threatened species. Weekly samples were sufficient only for reptiles and mammals, considered separately. Richness
estimated from the biweekly samples was equal to that found in the weekly samples, and gave satisfactory results for sampling
the most abundant and threatened species. The ten most affected species showed constant road-mortality rates, independent
of sampling interval, and also maintained their dominance structure. Birds required greater sampling effort. When the composition
of road-killed species varies seasonally, it is necessary to take biweekly samples for a minimum of one year. Weekly or more-frequent
sampling for periods longer than two years is necessary to provide a reliable estimate of total species richness. 相似文献
83.
The coming century is predicted to feature enhanced climatic variability, including increased frequency, intensity, and duration of extreme climatic events. Ecologists are faced with the critical challenge of anticipating potentially nonlinear ecosystem responses to these changes. High-resolution paleoecological data sets that capture past ecosystem responses to climate variability provide valuable long-term perspectives on the sensitivity of ecosystems to climate-forced state shifts. We used a suite of paleoecological analyses at Titus Bog in northwestern Pennsylvania, USA, to test the hypothesis that the development and expansion of floating peatlands in kettlehole basins represents a threshold response to hydroclimate variability. In contrast with expectations of gradual autogenic peat mat expansion, our results indicate that peat mat expansion at Titus Bog was highly episodic and occurred in three distinct pulses centered on 800, 650, and 400 cal yr BP. Each of these expansion events coincided with or immediately followed decadal-to-mutlidecadal droughts recorded in regional paleoclimate reconstructions. These patterns indicate that peatland development in kettlehole basins can follow nonlinear trajectories, with episodes of rapid advancement triggered by climatic forcing. Future climate changes may increase the likelihood of peatland expansion in kettlehole basins, potentially leading to abrupt changes in adjacent lake ecosystems. 相似文献
84.
Michael Lockwood 《Journal of Environmental Planning and Management》1996,39(3):357-370
The contingent valuation method (CVM) can be useful for assessing the non-market economic values associated with government land use decisions. A particular variant of CVM, which is based on dichotomous choice responses, has become widely used. Previous studies have employed a variety of techniques for analysing dichotomous choice CVM data to produce estimates of economic welfare changes. This paper summarizes these analytical options, and illustrates their application in a case study concerning cattle grazing on the Bogong High Plains in the Australian Alps. This case study is one of the few to assess the non-market economic value of cultural heritage conservation using contingent valuation, and is also unusual in that the competing values are both non-market in character. Nature conservation and heritage values were separately measured using two independent surveys. Mean willingness to pay for nature conservation and cultural heritage were estimated using a range of parametric and nonparametric methods. 相似文献
85.
Kamala Kanta Sahu Thomas C Alex Devabrata Mishra Archana Agrawal 《Waste management & research》2006,24(1):74-79
To recover pigment grade TiO2, operating plants all over the world use chemical processes. Slag-based technology is considered to be attractive because of low waste generation and low chemical cost due to high titanium content and is poised to replace the conventional technology. This paper provides a review of the slag-based technology with the specific aim to produce leachable slag and achieving high titania yield from recovered wastes. Leachable oxides of the lower oxidation state, such as TiO and Ti2O3, facilitate the leaching process. However, during smelting these oxides increase the viscosity of the slag. Formation of titanium carbide or carbonitride is also not desirable as it leads to resistance to the leaching of titanium. This report highlights the problems and their possible solutions to obtain leachable slag. 相似文献
86.
Emily Boyd Nate Hultman J. Timmons Roberts Esteve Corbera John Cole Alex Bozmoski Johannes Ebeling Robert Tippman Philip Mann Katrina Brown Diana M. Liverman 《Environmental Science & Policy》2009,12(7):820-831
The Clean Development Mechanism (CDM) has successfully demonstrated that market-based mechanisms can achieve some cost effective emissions reductions in developing countries. However the distribution of CDM projects has been extremely uneven across countries and regions, and a few technologies and sectors have dominated the early stages of CDM experience. This has caused some to question whether the CDM has fallen short of its potential in contributing to sustainable development. We review the broad patterns of CDM project approvals and evaluate 10 CDM projects according to their sustainability benefits. The difficulty of defining “sustainable development” and the process of defining criteria by individual non-Annex 1 governments has meant that sustainable development concerns have been marginalized in some countries. Given these observed limitations, we present possible CDM policy futures, focusing on the main proposals for a post-2012 climate regime. Five options for enhancing the sustainable development benefits in the CDM are discussed, including proactive approaches to favour eligibility of emission reduction projects which ensure such co-benefits. 相似文献
87.
气象模拟误差对异戊二烯排放估算的影响 总被引:3,自引:3,他引:0
利用MEGAN模式估算了珠三角地区2006年异戊二烯的排放情况,并设计了两组敏感性实验深入探讨了气象模拟误差对异戊二烯排放的影响.估算结果显示,2006年珠三角地区异戊二烯的排放量为95.56×106kg(以C计),且主要分布在珠三角地区周边植被覆盖较高的地方;受气象条件季节变化的影响,异戊二烯的排放表现出显著的季节和日变化特征,最大异戊二烯排放通量季节出现在夏季,为0.920t·km-2(以C计),最大排放速率均出现在13:00.敏感性实验结果显示,气象模拟误差能显著影响异戊二烯的排放,升高(降低)太阳辐射的输入,异戊二烯的排放量增加(减小)36.20%~50.70%(30.73%~41.88%),大于温度改变引起的排放量变化;升高(降低)气象输入并不会改变异戊二烯排放的日变化特征,但能显著影响排放速率的大小.上午8:00或下午17:00,异戊二烯排放速率的改变最为明显. 相似文献
88.
Kol-Maimon H Levi-Zada A Franco JC Dunkelblum E Protasov A Eliyaho M Mendel Z 《Die Naturwissenschaften》2010,97(12):1047-1057
The vine mealybug (VM) females collected in Israel produce two sex pheromone compounds: lavandulyl senecioate (LS) and (S)-lavandulyl isovalerate (LI). The males display ambiguous behavior to LI: repulsion in the vineyard and attraction of laboratory-reared
males. We addressed the question of individual male behavior, i.e., do males respond to both LS and LI, or might they display
a distinct response to each of the two pheromone compounds. We compared male pherotype frequencies between wild-caught and
laboratory-reared populations. Then, we examined the relationship between pherotype composition and male capture rates in
pheromone traps. Finally, we addressed the heredity of the pherotypes. The Israeli VM populations contain nine different male
pherotypes, as defined according to the male behavior to pheromone compounds. The studied Portuguese populations included
five of the nine pherotypes; none of the Portuguese males were attracted to LI. It seems that the high frequency of males
that were attracted to LI is related to dense VM populations. It is hypothesized that selection for the male pherotypes, I
males, those that respond to LI, occur under high-density rearing conditions. This may result from shorter development times
of males and females that produce more I male pherotypes. The lower relative frequency of trapping of males in LI-baited traps
than expected from the percentage determined in a Petri dish arena suggests that males that respond solely to LS (S males)
are better fliers. The results also suggest that the pherotype trait is inherited by both sexes of the VM. 相似文献
89.
A hybrid process for manufacturing surgical-grade knife blade cutting edges from bulk metallic glass
Alex J. Krejcie Shiv G. Kapoor Richard E. DeVor 《Journal of Manufacturing Processes》2012,14(1):26-34
The demand for precision surgical knives is enormous. Currently, diamond knives have been the preferred choice among surgeons for use in precision surgeries, owing to the extreme hardness of diamond and the sharpness that can be achieved in single crystal diamond blades, but material and processing costs are high. Bulk metallic glass (BMG) has the potential to be an economically viable material of similar performance for use in precision surgical knives. To this end, a novel hybrid manufacturing process integrating thermally assisted micro-molding and micro-drawing has been developed for producing BMG surgical-grade knife blade cutting edges with edge radii <50 nm. A hybrid process testbed was designed and used to successfully run tests over a range of the key process variables. Through this testing the deformation of BMG under different strain rates and temperatures was studied in terms of the quality of edge formation. The hybrid process was shown to be capable of producing cutting edges of radius at or below 100 nm. 相似文献
90.
Surfactant-enhanced aquifer remediation (SEAR) involves the injection of surfactant solutions into aquifers contaminated with nonaqueous phase liquids (NAPL). Batch and column experiments were used to assess the effect of surfactant formulation on the rate of NAPL solubilization. The experimental variables were surfactant type, surfactant concentration, electrolyte concentration, and cosolvent concentration. Model equations were proposed and solved to describe solubilization under the conditions of each type of experiment. Using these models, a solubilization rate constant, kappa(b), and an overall mass transfer rate coefficient, kappa, were estimated from the batch and column experiments, respectively. The solubilization rate constant was consistently sensitive to surfactant type, surfactant concentration, and electrolyte concentration. The estimated solubilization rate constants varied over two orders of magnitude. The results of the column experiments also were sensitive to the surfactant formulation. Variations in the fitted mass transfer rate coefficient parameter, beta(0), were related to variations in the surfactant formulations. A comparison between the results of the batch and column experiments yields an apparent relationship between beta(0) and kappa(b). This relationship suggests that the mass transfer rate coefficient is directly related to the formulation of the surfactant solution. 相似文献