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111.
Environmental Science and Pollution Research - The new coronavirus SARS-CoV-2 has infected more than 14 million people worldwide so far. Brazil is currently the second leading country in number of...  相似文献   
112.
Simulations using global coupled climate models predict a climate change due to the increasing concentration of greenhouse gases and aerosols in the atmosphere. Both are associated with the burning of fossil fuels. There has been considerable debate if this postulated human influence is already evident. This paper gives an overview on some recent material on this question. One particular study using optimal fingerprints (Hegerl et al., 1996) is explained in more detail. In this study, an optimal fingerprint analysis is applied to temperature trend patterns over several decades. The results show the probability being less than 5% that the most recently observed 30 year trend is due to naturally occurring climate fluctuations. This result suggests that the present warming is caused by some external influence on climate, e.g. by the increasing concentrations of greenhouse gases and aerosols. More work is needed to address the uncertainties in the magnitude of naturally occurring climate fluctuations. Also, other external influences on climate need to be investigated to uniquely attribute the present climate change to the human influence.  相似文献   
113.
人工神经网络在沿海区域环境复杂系统预测中的应用   总被引:6,自引:0,他引:6  
针对复杂系统的非线性特征,分析了应用人工神经网络技术实现可持续发展复杂系统预测的可能性,并以上海市和崇明县为例建立沿海区域预测模型,取得了较好的预测结果,为可持续发展复杂系统的预测研究探索了一种新的可能方法。  相似文献   
114.
Polychlorinated biphenyls (PCBs), a group of 209 congeners that differ in the number and position of chlorines on the biphenyl ring, are anthropogenic chemicals that belong to the persistent organic pollutants (POPs). For many years, PCBs have been a topic of interest because of their biomagnification in the food chain and their environmental persistence. PCBs with fewer chlorine atoms, however, are less persistent and more susceptible to metabolic attack, giving rise to chemicals characterized by the addition of one or more hydroxyl groups to the chlorinated biphenyl skeleton, collectively known as hydroxylated PCBs (OH-PCBs). In animals and plants, this biotransformation of PCBs to OH-PCBs is primarily carried out by cytochrome P-450-dependent monooxygenases. One of the reasons for infrequent detection of lower chlorinated PCBs in serum and other biological matrices is their shorter half-lives, and their metabolic transformation, resulting in OH-PCBs or their conjugates, such as sulfates and glucuronides, or macromolecule adducts. Recent biomonitoring studies have reported the presence of OH-PCBs in human serum. The occurrence of OH-PCBs, the size of this group (there are 837 mono-hydroxyl PCBs alone), and their wide spectra of physical characteristics (pKa’s and log P’s ranging over 5 to 6 orders of magnitude) give rise to a multiplicity of biological effects. Among those are bioactivation to electrophilic metabolites that can form covalent adducts with DNA and other macromolecules, interference with hormonal signaling, inhibition of enzymes that regulate cellular concentrations of active hormones, and interference with the transport of hormones. This new information creates an urgent need for a new perspective on these often overlooked metabolites.  相似文献   
115.
Effective support of inherent safety implementation in process design requires a quantitative metric for monitoring and communicating the expected safety performance of alternative design options. The Inherent Safety Key Performance Indicators (IS-KPIs) methodology was developed to provide both a flexible procedure for the identification of the hazards, and a sound consequence-based quantification of the safety performance. The integration of different hazard identification techniques yields the relevant accident scenarios for each unit in the plant. The calculation of credible damage distances by consolidate consequence simulation models provides a sound basis for the definition of the KPIs based on worst case effects. Specific indicators were devoted to hazards from external actions, as natural events and intentional malicious acts. The methodology was demonstrated by the comparison of alternative technological options for LNG regasification. The application evidenced the potential of the IS-KPI method in pinpointing the critical issues related to each alternative configuration.  相似文献   
116.
Urban MC 《Ecology》2007,88(10):2587-2597
Growth is a critical ecological trait because it can determine population demography, evolution, and community interactions. Predation risk frequently induces decreased foraging and slow growth in prey. However, such strategies may not always be favored when prey can outgrow a predator's hunting ability. At the same time, a growing gape-limited predator broadens its hunting ability through time by expanding its gape and thereby creates a moving size refuge for susceptible prey. Here, I explore the ramifications of growing gape-limited predators for adaptive prey growth. A discrete demographic model for optimal foraging/growth strategies was derived under the realistic scenario of gape-limited and gape-unconstrained predation threats. Analytic and numerical results demonstrate a novel fitness minimum just above the growth rate of the gape-limited predator. This local fitness minimum separates a slow growth strategy that forages infrequently and accumulates low but constant predation risk from a fast growth strategy that forages frequently and experiences a high early predation risk in return for lower future predation risk and enhanced fecundity. Slow strategies generally were advantageous in communities dominated by gape-unconstrained predators whereas fast strategies were advantageous in gape-limited predator communities. Results were sensitive to the assumed relationships between prey size and fecundity and between prey growth and predation risk. Predator growth increased the parameter space favoring fast prey strategies. The model makes the testable predictions that prey should not grow at the same rate as their gape-limited predator and generally should grow faster than the fastest growing gape-limited predator. By focusing on predator constraints on prey capture, these results integrate the ecological and evolutionary implications of prey growth in diverse predator communities and offer an explanation for empirical growth patterns previously viewed to be anomalies.  相似文献   
117.
Soil samples from the area of Hanau (Hessen, Germany) were analyzed for anthropogenic platinum-group elements (PGE). The results confirm the existence of two different sources for anthropogenic PGE: 1. automotive catalysts, and 2. PGE-processing plants. Both sources emit qualitatively and quantitatively different PGE spectra and PGE interelemental ratios (especially the Pt/Rh ratio). Elevated PGE values which are due to automotive catalysts are restricted to a narrow-range along roadside soil, whereas those due to PGE-processing plants display a large-area dispersion. The emitted PGE-containing particles in the case of automotive catalysts are subject to transport by wind and water, whereas those from PGE-processing plants are preferably transported by wind. This points to a different aerodynamic particle size. Pt, Pd, and Rh concentrations along motorways are dependent on the amount of traffic and the driving characteristics.  相似文献   
118.
The present study was done to assess the sources and the major processes controlling the trace metal distribution in sediments of Buckingham Canal. Based on the observed geochemical variations, the sediments are grouped as South Buckingham Canal and North Buckingham Canal sediments (SBC and NBC, respectively). SBC sediments show enrichment in Fe, Ti, Mn, Cr, V, Mo, and As concentrations, while NBC sediments show enrichment in Sn, Cu, Pb, Zn, Ni, and Hg. The calculated Chemical Index of Alteration and Chemical Index of Weathering values for all the sediments are relatively higher than the North American Shale Composite and Upper Continental Crust but similar to Post-Archaean Average Shale, and suggest a source area with moderate weathering. Overall, SBC sediments are highly enriched in Mo, Zn, Cu, and Hg (geoaccumulation index (Igeo) class 4–6), whereas NBC sediments are enriched in Sn, Cu, Zn, and Hg (Igeo class 4–6). Cu, Ni, and Cr show higher than Effects-Range Median values and hence the biological adverse effect of these metals is 20%; Zn, which accounts for 50%, in the NBC sediments, has a more biological adverse effect than other metals found in these sediments. The calculated Igeo, Enrichment Factor, and Contamination Factor values indicate that Mo, Hg, Sn, Cu, and Zn are highly enriched in the Buckingham Canal sediments, suggesting the rapid urban and industrial development of Chennai Metropolitan City have negatively influenced on the surrounding aquatic ecosystem.  相似文献   
119.
Sperm competition is a potent driving force in evolution leading to a remarkable variety of male adaptations that prevent or reduce fertilization by rivals. An extraordinary defensive strategy against sperm competition has evolved in a number of web spiders where males break off parts of their paired genitalia in order to obstruct the copulatory openings of females (mating plug). A recent comparative analysis on the family level reports that genital damage is most frequent in species with sexual cannibalism although, as yet, a functional association between sexual cannibalism and genital damage has not been found. Using the moderately sexually cannibalistic orb-web spider Argiope lobata, we show for the first time that males cannibalized during their first copulation damaged their pedipalps with significantly higher probability (74%) than males that escaped (15%). Of all males that damaged their genitalia, 44% were able to place a genital fragment inside the copulatory opening of the female, resulting in a relatively low total plugging rate of 14%. Successful obstruction of the female copulatory opening reduced the share of paternity of subsequent males (P 2 = 0.06%), thus, indicating that genital damage may have evolved as a response to sperm competition in this species as well. However, the low incidence of successful plugging and the strong relationship between sexual cannibalism and genital damage suggest that apart from paternity protection, the nature of genital damage in A. lobata is further shaped by sexual conflict or cryptic female choice.  相似文献   
120.
The fundamental way of satisfying the basic needs of human development is to secure the basic needs,limit luxurious and wasteful emissions,and ensure the fulfillment of climate targets,so as to achieve intra-and intergenerational equity.In this paper,the author discusses and analyzes a series of challenges that the development has to face,such as poverty elimination,urbanization,and industrialization,and the problems of increased consumption that is brought about by the improvement of living standards;the author distinguishes the stock emission,which does not need annual updating,and the flow emission of regular consumption;the author also defines the standards of energy consumption and carbon emissions that can meet the basic needs.On this basis,the author proposes the concept and method of carbon budget,compares this method with other means,and in particular,studies and analyzes the implications of international equity and sustainability of carbon budget as part of the international climate regime design.  相似文献   
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