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331.
A current model suggests that magnetoreception of compass information starts with light-dependent primary processes. Light-dependency of magnetoreception is supported by behavioral experiments with homing pigeons and caged migratory birds. Three passerine species showed normal orientation under dim monochromatic light from the blue-green range of the spectrum, while they were disoriented under yellow and red light. A sevenfold increase in intensity and pre-exposure to specific wavelengths caused changes in behavior. The behavioral data indicate a complex relationship between the wavelength of light and magnetoreception, suggesting the involvement of more than one type of receptors. Extracellular recordings from the nucleus of the basal optic root and the tectum opticum identified units that responded to changes in magnetic North. Each unit showed a peak in a distinct spatial direction, so that the input of these units, processed collectively and integrated, would indicate compass directions. 相似文献
332.
European robins tested under monochromatic green light with a peak wavelength of 565 nm at an intensity of 2.1 mW m-2 in the local geomagnetic field preferred their migratory direction, heading southward in autumn and northward in spring. Inverting of the vertical component of the magnetic field caused the robins to reverse their headings, indicating that the birds used a magnetic inclination compass to locate their migratory direction. The behavior recorded under green light at an intensity of 2.1 mW m-2 is thus not different from that previously recorded under "white" light; it represents normal migratory orientation. 相似文献
333.
Effects of ignitors and turbulence on dust explosions 总被引:1,自引:0,他引:1
Guangping Zhen Wolfgang Leuckel 《Journal of Loss Prevention in the Process Industries》1997,10(5-6):317-324
The aim of this work is in an attempt to increase the understanding of the acting behaviour of pyrotechnic ignitors and their effects on confined dust explosions. Flame visualization has shown that pyrotechnic ignitors can initiate an explosion by instantaneous jet-like volumetric and/or multipoint ignition. Hence, the rate of pressure rise and also the apparent burning velocity will be increased to some extent, depending on the ignitor energy and the reactivity of the mixtures. The ignitor effect is more important for the early stages of flame propagation and would be more significant in small explosion chambers. Thus, for dust explosion tests with various purposes, use of pyrotechnic ignitors should be made carefully, and the ignitor effect must be accounted for in the data interpretation. Turbulence induced by dust dispersion is a dominant factor in affecting dust explosions. At different ignition delays, however, the turbulence influence will be coupled with that of ignitors. This complicates further the interpretation of explosion data measured under turbulent conditions. 相似文献
334.
Lignite mining and processing has caused a pronounced impact both directly and indirectly on soils and ecosystems across large
areas of the former GDR. We studied soils of pine forest ecosystems at sites affected by severe alkaline dust and sulphur
deposition, stemming from lignite fired power plant emission, and at dumped sites from lignite mining. In this paper we summarize
our main results and evaluate the long-term impact of lignite mining and combustion on the environment.
The pine ecosystems on naturally developed soils show a clear effect of deposition history along a former deposition gradient
with distinct changes in chemical properties of organic surface layers and mineral soil as well as in element turnover and
cycling rates.
Afforested sites on mining dumps are directly affected by the composition of the dumped substrates. Over a large area (800
km2) these substrates are dominated by Tertiary sediments with varying amounts of lignitic particles and pyrite that result in
phytotoxic site conditions (pH < 3, high salt and metal contents). High amelioration doses of liming material (up to 200 t
ha−1) were applied for restoration purposes. We studied the development of these sites over a period of 60 years using a false-time
series approach. Beside the extreme soil conditions, element budgets of these sites are characterized by very high element
release rates over decades caused by pyrite oxidation and primary mineral weathering. 相似文献
335.
Wolfgang Schaaf Reinhard F. Hüttl John Scullion 《Water, Air, & Soil Pollution: Focus》2006,6(3-4):233-234
336.
Wolfgang Sterk Ralf Schüle 《Mitigation and Adaptation Strategies for Global Change》2009,14(5):409-431
More and more countries are incorporating the instrument of emissions trading into their national climate policies. This emerging
mosaic of emissions trading schemes (ETS) raises the question of whether they should be linked with each other. From an economic
point of view, linking of domestic schemes is supposed to increase the economic efficiency of carbon markets. In addition,
linking is also expected by some to yield substantial political benefits in terms of the evolution of the UNFCCC/Kyoto regime.
However, these optimistic prospects are based on a best-case scenario where all major countries establish environmentally
effective emissions trading systems and then link them with each other. Real-life politics might develop rather differently.
This paper therefore examines to what extent the current status of emissions trading in industrialised countries provides
a basis for reinforcing and moving forward the international climate regime through linking domestic ETS. After comparing
emerging emissions trading schemes from an institutional perspective, it emerges that not only emissions trading is at a very
early stage in most countries, in addition the emerging systems are probably going to be designed very differently from the
EU ETS. While for some design features such as the coverage design differences do not matter, there are some areas where the
plans in many non-EU countries look crucially different from the EU system. The outlook for a linked international ETS is
therefore currently still very uncertain. Given this state of affairs, the EU should pro-actively engage with the non-EU countries
to try to harmonise their developing national emissions trading schemes with the EU ETS, widely disseminate the lessons it
has learned from the EU ETS, strongly make the case for environmental integrity and at the same time make clear that systems
that want to link to the EU ETS will need to meet certain quality criteria.
相似文献
Ralf SchüleEmail: |
337.
Thomas S. Muenz Alban Maisonnasse Erika Plettner Yves Le Conte Wolfgang R?ssler 《Die Naturwissenschaften》2012,99(5):421-425
Social work force distribution in honeybee colonies critically depends on subtle adjustments of an age-related polyethism. Pheromones play a crucial role in adjusting physiological and behavioral maturation of nurse bees to foragers. In addition to primer effects of brood pheromone and queen mandibular pheromone—both were shown to influence onset of foraging—direct worker–worker interactions influence adult behavioral maturation. These interactions were narrowed down to the primer pheromone ethyl oleate, which is present at high concentrations in foragers, almost absent in young bees and was shown to delay the onset of foraging. Based on chemical analyses, physiological recordings from the antenna (electroantennograms) and the antennal lobe (calcium imaging), and behavioral assays (associative conditioning of the proboscis extension response), we present evidence that ethyl oleate is most abundant on the cuticle, received by olfactory receptors on the antenna, processed in glomeruli of the antennal lobe, and learned in olfactory centers of the brain. The results are highly suggestive that the primer pheromone ethyl oleate is transmitted and perceived between individuals via olfaction at close range. 相似文献
338.
339.
340.
Recent measurements at different locations suggest that the emission of mercury from soils may play a more pronounced role in the global mercury cycle as suggested by global emission inventories and global mercury cycling models. For up scaling and modelling of mercury emissions from soils a comprehensive assessment of the processes controlling the emission of mercury from soils is imperative. We have developed a laboratory flux measurement system (LFMS) to study the effect of major environmental variables on the emission of mercury under controlled conditions. We have investigated the effects of turbulent mixing, soil temperature and solar radiation on the emission of mercury from soils. The emission of mercury from soils is constant over time under constant experimental conditions. The response of the mercury emission flux to variations of the atmospheric transfer parameters such as turbulence requires a rapid adjustment of the equilibrium that controls the Hg(o) concentration in the soil air. It has been shown that the light-induced flux is independent of the soil temperature and shows a strong spectral response to UV-B. 相似文献