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The chemical composition of the troposphere is controlled by various biogeochemical cycles that couple the atmosphere with the oceans, the solid Earth and the biosphere, and by atmospheric photochemical/chemical reactions. These cycles and reactions are discussed and a number of key questions concerning tropospheric composition and chemistry for the carbon, nitrogen, oxygen and sulfur species are identified. Next, we review various remote sensing techniques and instruments capable of measuring and monitoring tropospheric species from the ground, aircraft and space to address some of these key questions. We also consider future thrusts in remote sensing of the troposphere. 相似文献
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Deana M. Crumbling Joel S. Hayworth Bradley A. Call William M. Davis Robert Howe David S. Miller Robert Johnson 《补救:环境净化治理成本、技术与工艺杂志》2004,14(4):81-96
Misunderstandings and misconceptions have arisen as the Triad approach has gained wider application. The Triad initiative's ability to catalyze second‐generation cleanup practices will be hampered if inaccurate or incomplete assumptions create persistent confusion about what Triad is or how it works. This article has been prepared by the multi‐agency workgroup responsible for articulating the Triad approach and coordinating national Triad efforts. It serves to address some misunderstandings about key Triad concepts. As an aid to those wishing to learn more, a new Web site (the Triad Resource Center, http://www.triadcentral.org) and a new Triad reference document from the Interstate Technology and Regulatory Council (ITRC) are introduced as sources of explanatory information supporting the Triad approach. © 2004 Wiley Periodicals, Inc. 相似文献
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Biesmeijer JC Giurfa M Koedam D Potts SG Joel DM Dafni A 《Die Naturwissenschaften》2005,92(9):444-450
Several recent hypotheses, including sensory drive and sensory exploitation, suggest that receiver biases may drive selection
of biological signals in the context of sexual selection. Here we suggest that a similar mechanism may have led to convergence
of patterns in flowers, stingless bee nest entrances, and pitchers of insectivorous plants. A survey of these non-related
visual stimuli shows that they share features such as stripes, dark centre, and peripheral dots. Next, we experimentally show
that in stingless bees the close-up approach to a flower is guided by dark centre preference. Moreover, in the approach towards
their nest entrance, they have a spontaneous preference for entrance patterns containing a dark centre and disrupted ornamentation.
Together with existing empirical evidence on the honeybee's and other insects’ orientation to flowers, this suggests that
the signal receivers of the natural patterns we examined, mainly Hymenoptera, have spontaneous preferences for radiating stripes,
dark centres, and peripheral dots. These receiver biases may have evolved in other behavioural contexts in the ancestors of
Hymenoptera, but our findings suggest that they have triggered the convergent evolution of visual stimuli in floral guides,
stingless bee nest entrances, and insectivorous pitchers. 相似文献