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211.
Die Kenntnis biochemischer Veränderungen von lipophilen körperfremden Stoffen ist hinsichtlich deren Elimination aus dem Organismus, sowie bei Überlegungen zur Voraussage toxischer, insbesondere carcinogener Wirkungen von vorrangiger Bedeutung 相似文献
212.
The hypotheses on the de novo syntheses of polychlorinated dibenzofurans (PCDFs) and polychlorinated dibenzo‐p‐dioxins (PCDDs), based on known literature, are presented. Polychlorinated benzenes and polychlorinated phenols are probably key intermediates. In the present article, hypotheses that may account for the presence of polychlorinated dibenzofurans (PCDFs) and dibenzo‐p‐dioxins (PCDDs) in the effluents from municipal and industrial incinerators are put forward. These hypotheses are based on the previously surveyed literature (Ref. 203–206) and experimental results on laboratory scale and thermodynamic calculations are considered. The interconnections of various reaction steps are speculative and no technological information was added to account for conditions in real incinerators. Conclusion of the discussions on the related subject matter, presented in the Parts I‐IV (Ref. 203–206), are also described in this paper. 相似文献
213.
SUMMARY Regional business concepts are said to have huge potential to support sustainable development in industrialised countries (e.g. Stransfeld, 1999). However, whereas efforts have been made to implement regional concepts within agriculture and forestry, empirical findings show that regional concepts are only of minor importance to managers within industrial production (Rentz et al., 2000). Considering this situation, the aim of the present article is to explain why regional business concepts have rarely been implemented in the field of industrial production. Therefore, in the course of the present article, a raster for the identification of relevant barriers on a personal, enterprise, inter-firm and macroeconomic level will be developed and applied. Subsequently, suggestions for a set of measures to overcome these barriers to regionalisation will be given. The results have been identified in the framework of a questionnaire to about 30 decision makers of industrial companies within research, a project promoted by the German Ministry of Education and Research. 相似文献
214.
Ricardo A. Rodríguez Ada M. HerreraRüdiger Otto Juan D. DelgadoJosé M. Fernández-Palacios José R. Arévalo 《Ecological modelling》2012,224(1):18-24
The direct equivalence between ecology and thermodynamics has not been attained despite accepted thermodynamic features of the ecosystem. This article explores the homeomorphism between ecology and statistical mechanics by analysis of ruderal vegetation. In conventional thermostatistical algorithm, the pro-kinetic effect of temperature on molecules was replaced by the anti-kinetic effect of species diversity on biological individuals. The existence of an ecological equivalent of the thermodynamic Boltzmann constant was empirically verified. From the relationship of this constant with biocenological variables, we derived a probable ecological equation of state under stationary and quasi-stationary conditions. This equation of state is homeomorphic with regard to the ideal gas state equation, and it is useful to infer the value of some biocenological parameters whose direct measurement is difficult, as biomass, energy and dispersal. According to these results, ecosystem assessment from conventional thermostatistics is plausible and empirically verifiable. This approach offers useful analytical tools for the conservation and restoration of ecosystems. 相似文献
215.
Christopher N. Templeton ?a?lar Ak?ay S. Elizabeth Campbell Michael D. Beecher 《Behavioral ecology and sociobiology》2012,66(11):1503-1509
Animals frequently use signals to modulate aggressive interactions. Establishing that a signal is aggressive or threatening requires demonstrating that it is more commonly used in agonistic contexts, that it predicts subsequent aggressive behaviors by the sender, and that receivers respond differently to this signal. Like many birds, song sparrows (Melospiza melodia) produce a low-amplitude “soft song” vocalization that has been hypothesized to be an aggressive signal. Soft song meets the first two criteria, but previous research has failed to demonstrate that soft song provokes aggression or that receivers even perceive soft song differently from normal loud song. We used a playback experiment with taxidermic mount presentation to test whether territorial male song sparrows respond differently to loud and soft song playbacks. Subjects reacted more strongly to the soft song playback by approaching the mount more closely, increasing wing wave displays, and increasing the proportion of their own songs that were soft songs, with further trends toward increasing the number of flights and attacks. These results confirm that soft song is a conventional signal of aggression in song sparrows and that increased receiver retaliation maintains its reliability. 相似文献
216.
Cleland EE Allen JM Crimmins TM Dunne JA Pau S Travers SE Zavaleta ES Wolkovich EM 《Ecology》2012,93(8):1765-1771
Earlier spring phenology observed in many plant species in recent decades provides compelling evidence that species are already responding to the rising global temperatures associated with anthropogenic climate change. There is great variability among species, however, in their phenological sensitivity to temperature. Species that do not phenologically "track" climate change may be at a disadvantage if their growth becomes limited by missed interactions with mutualists, or a shorter growing season relative to earlier-active competitors. Here, we set out to test the hypothesis that phenological sensitivity could be used to predict species performance in a warming climate, by synthesizing results across terrestrial warming experiments. We assembled data for 57 species across 24 studies where flowering or vegetative phenology was matched with a measure of species performance. Performance metrics included biomass, percent cover, number of flowers, or individual growth. We found that species that advanced their phenology with warming also increased their performance, whereas those that did not advance tended to decline in performance with warming. This indicates that species that cannot phenologically "track" climate may be at increased risk with future climate change, and it suggests that phenological monitoring may provide an important tool for setting future conservation priorities. 相似文献
217.
Sylvia Moenickes Marieke Frassl Jeanette Schlief Moritz Kupisch Michael Mutz Frank Suhling Otto Richter 《Marine Biology》2012,159(11):2605-2620
In this paper, we present an approach for describing the environmentally induced temporal pattern of structured populations by partial integro-differential equations. Populations are structured according to size or stage. Growth, energy allocation and stage transitions are affected by environmental conditions of which temperature, photoperiod, water depth and food supply were taken into account. The resulting modelling framework was applied to describe, analyse and predict alterations in populations with continuous development, populations with distinct state structures and interacting populations. Our exemplary applications consider populations of freshwater Amphipoda, Isopoda and Odonata. The model was capable of simulating life cycle alterations in dependence on temperature in interaction with other environmental factors: (1) population dynamics, (2) seasonal regulation, (3) water depth-dependent dispersal, (4) intraguild predation and (5) consumer-resource dynamics. 相似文献
218.
Quantitative polymerase chain reaction (qPCR) for the identification and quantification of microbes has become a common tool
for the study of harmful algal blooms (HABs). We developed a qPCR method for the diatom genus Pseudo-nitzschia. Several species of this genus form toxic blooms through the production of the neurotoxin domoic acid (DA). Outbreaks of
toxicity attributed to DA along the US west coast have caused sickness and death of marine mammals and seabirds through food
web contamination. The method developed here quantifies Pseudo-nitzschia spp. at low abundances in natural samples, thereby, providing a method to improve our understanding of the environmental
conditions leading to blooms of these species. This has been accomplished previously by techniques for identification and
quantification that are slow and laborious compared to qPCR. The approach was successfully tested and validated using eight
species of Pseudo-nitzschia and 33 non-target organisms and employed to follow local bloom dynamics. 相似文献
219.
The indirect, ecosystem-level consequences of ocean fishing, and particularly the mechanisms driving them, are poorly understood. Most studies focus on density-mediated trophic cascades, where removal of predators alternately causes increases and decreases in abundances of lower trophic levels. However, cascades could also be driven by where and when prey forage rather than solely by prey abundance. Over a large gradient of fishing intensity in the central Pacific's remote northern Line Islands, including a nearly pristine, baseline coral reef system, we found that changes in predation risk elicit strong behavioral responses in foraging patterns across multiple prey fish species. These responses were observed as a function of both short-term ("acute") risk and longer-term ("chronic") risk, as well as when prey were exposed to model predators to isolate the effect of perceived predation risk from other potentially confounding factors. Compared to numerical prey responses, antipredator behavioral responses such as these can potentially have far greater net impacts (by occurring over entire assemblages) and operate over shorter temporal scales (with potentially instantaneous response times) in transmitting top-down effects. A rich body of literature exists on both the direct effects of human removal of predators from ecosystems and predators' effects on prey behavior. Our results draw together these lines of research and provide the first empirical evidence that large-scale human removal of predators from a natural ecosystem indirectly alters prey behavior. These behavioral changes may, in turn, drive previously unsuspected alterations in reef food webs. 相似文献
220.
Many species of marine fish are typified by large population sizes, strong migratory behavior, high fecundity, and pelagic
eggs and larvae that are passively transported by ocean currents, all features that tend to increase gene flow, and hence
reduce genetic partitioning, among localized populations. The plaice, Pleuronectes platessa, is a commercially important demersal species that exhibits all of these characteristics. We analyzed genetic variation at
eight microsatellite loci in samples of spawning adults (N = 348) from the coasts of Ireland, Iceland, and, for the first time, from the Baltic Sea. Significant differentiation was
observed between Iceland and Irish and Baltic Sea samples. However, there were no genetic differences between Irish and Baltic
Sea samples, which contrast with the significant differentiation reported between Baltic Sea and North Sea/Atlantic populations
of other flatfish species. To increase the data set, we carried out a cross-calibration exercise, allowing us to perform a
joint analysis of data with an earlier study on adult and juvenile plaice (N = 480) collected over a broad geographic range, using six microsatellite loci in common to the two studies. Significant differentiation
was observed between fish collected at the northern (Iceland, Faeroes, Norway) and southern (Bay of Biscay) parts of the species
range. In contrast, the results showed little evidence of genetic structuring over much of the continental shelf of Europe.
We believe that bathymetric and hydrographic barriers are the major factors shaping genetic structure, while lack of structure
over much of the European continental shelf may be explained by a combination of past historical events, population structure,
and dynamics of the species. 相似文献