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191.
The microhabitat of Symbion pandora (Cycliophora) was described by recording the prevalence and distribution of two life cycle stages, namely feeding individuals
and chordoid cysts on the mouth appendages of 65 Norway lobsters. The commensals infested lobsters with a carapace length
>35 mm, while the intensity of the commensals increased with host size up to more than 1,100 feeding individuals and 173 chordoid
cysts. Feeding individuals and chordoid cysts were found on all six pairs of mouth appendages, but were rare on Mxp3. A Kruskal–Wallis
analysis of variance showed that the distribution of the two stages over individual segments deviated significantly from random
expectations (P<0.001). Feeding individuals densely aggregated on a few medial segments, generally those that are pervaded by suspended food
particles during host feeding. Chordoid cysts, which arise from non-feeding females occurred in low numbers and were more
evenly distributed over the segments, often aggregating on the lateral parts and in the articulations of the segments. Based
on these findings we suggest that the feeding activity of S. pandora is synchronized with that of the host. 相似文献
192.
193.
谈起善于利用媒体的政客,德国前总理施罗德一定名列前茅.就在2002年德国大选数周前,面临连任的他在民调中仍然大幅落后.然而一场百年不遇的洪灾过后,施罗德赢得了国民以及以刁钻刻薄闻名的德国媒体的一片好评,最终在大选中成功实现大逆反.这一成功很大程度上取决于施罗德的危机公关处理能力. 相似文献
194.
195.
Michael P. Harris Doug Beare Reidar Toresen Leif Nøttestad Matthias Kloppmann Hendrik Dörner Kevin Peach Derek R. A. Rushton Judy Foster-Smith Sarah Wanless 《Marine Biology》2007,151(3):973-983
Since the early 2000s routine fish surveys have recorded increasing numbers of snake pipefish, Entelurus aequoreus, in the northeast Atlantic. Fishermen and divers have also commented on this increase and pipefish have started to appear
in the diet of seabirds and other marine predators. This paper collates information from these diverse sources and assesses
the current status of snake pipefish. We found compelling evidence of a dramatic increase in the abundance of snake pipefish
starting around 2003 and continuing up to the present (2006) and a range expansion northwards to Spitzbergen and the Barents
Sea. Since 2004 snake pipefish have been increasingly recorded in the diet of many species of seabird breeding in colonies
around the coast of the UK, and in Norway, Iceland and the Faeroe Islands. Information on the nutrient value of snake pipefish
is currently lacking but their rigid, bony structure makes them difficult for young seabirds to swallow and there are numerous
records of chicks choking to death. Thus, in the case of avian predators during the breeding season, it appears unlikely that
increased abundance of snake pipefish will provide a useful alternative prey. The reason for the rapid and dramatic increase
in numbers of snake pipefish is currently unclear but such events are characteristic of marine ecosystems and will almost
certainly have an effect on food web dynamics. 相似文献
196.
PD Dr. Rolf Altenburger Dr. Dana Kühnel Martin Bittens Dr. Birgit Daus Dr. Werner Brack Dr. Florian Centler Prof. Dr. Hauke Harms Dr. Martin Thullner Dr. Lukas Y. Wick Prof. Dr. Kai-Uwe Goss Prof. Dr. Frank-Dieter Kopinke Dr. Katrin Mackenzie Dr. Anja Miltner PD Dr. Matthias Liess Dr. Rainer Wennrich Dr. Anne E. Berns PD Dr. Peter Burauel 《Environmental Sciences Europe》2010,22(4):502-506
197.
Diana Reckien Klaus Eisenack Matthias K. B. Lüdeke 《Environmental Modeling and Assessment》2011,16(5):465-477
A new modelling approach to urban sprawl dynamics is introduced which allows representing qualitative knowledge on relations
between moving actor populations and properties of locations. The results of this Qualitative Attractiveness Migration (QuAM)
Model are scenario-like sets of possible future developments of the urban system, much in contrast to quantitative forecasts
gained by traditional modelling approaches. QuAM models allow for the interaction between internal dynamics and external influences.
The application of the new approach is exemplified by the case of urban sprawl in Leipzig since 1990. It was possible to reproduce
the observed qualitative development and to calculate future scenarios. The scenario runs project a new wave of middle class
driven residential sprawl and suggest implications for sprawl reducing policy interventions. 相似文献
198.
Transition to sustainability is a search for ways to improve the social capacity to guide interactions between nature and society toward a more sustainable future and, thus, a process of social learning in its broadest sense. Accordingly, it is not only learning that is at issue but education and educational science, of which the latter is about exploring the preconditions of and opportunities for learning and education—whether individual or social, in formal or informal settings. Analyzing how educational science deals with the challenge of sustainability leads to two complementary approaches: the ‘outside-in’ approach sees the idea of sustainability influencing educational practice and the way the relationship of learning and teaching is reviewed, theoretically as well as within the social context. In an ‘inside-out’ approach, an overview is given of how educational science can contribute to the field of sustainability science. An examination of the literature on education and sustainability shows that, while sustainability features prominently in one form or another across all sectors, only little work can be found dealing with the contributions of educational science within sustainability science. However, as sustainability is a concept that not only influences educational practices but also invites disciplinary contributions to foster inter- and transdisciplinary research within the sustainability discourse, the question remains as to how and to what extent educational science in particular can contribute to sustainability science in terms of an ‘inside-out’ approach. In this paper, we reconstruct the emergence of education for sustainable development as a distinctive field of educational science and introduce and discuss three areas of sustainability research and throw into relief the unique contribution that educational science can make to individual action and behavior change, to organizational change and social learning, and, finally, to inter- and transdisciplinary collaboration. 相似文献
199.
Zhiyuan Zhong Stefan Schneiderbauer Pieter J. Dijkstra Matthias Westerhausen Jan Feijen 《Journal of Polymers and the Environment》2001,9(1):31-38
The ring-opening polymerization of l-lactide with calcium alkoxides generated in-situ from bis(tetrahydrofuran)calcium bis[bis(trimethylsilyl)amide] and 2-propanol are presented. The polymerization in THF at room temperature proceeds rapidly and in a living manner, giving poly(l-lactide)s of controlled molecular weight, low polydispersity, and tailored end-functionalities. Kinetic studies show the absence of an induction period and a pseudo-first order rate constant of 6.41 L mol–1 min–1, which is significantly higher than for related Y5(-O)(O
i
Pr)13– or aluminum alkoxide-initiated polymerizations. The initiation involves a two-step process: (1) alcoholysis of bis(tetrahydrofuran)calcium bis[bis(trimethylsilyl)amide] to give the corresponding calcium alkoxide and (2) ring-opening of l-lactide via acyl-oxygen cleavage and insertion into the calcium-alkoxide bond. In the presence of excess alcohol, fast and reversible exchange between free alcohol molecules and coordinated alkoxide ligands takes place. This allows tuning of the poly(l-lactide) molecular weight over a wide range. 相似文献
200.
Oughton D Forsberg EM Bay I Kaiser M Howard B 《Journal of environmental radioactivity》2004,74(1-3):171-183
Experience after the Chernobyl accident has shown that restoration strategies need to consider a wide range of different issues to ensure the long-term sustainability of large and varied contaminated areas. Thus, the criteria by which we evaluate countermeasures need to be extended from simple cost-benefit effectiveness and radiological protection standards to a more integrated, holistic approach, including social and ethical aspects. Within the STRATEGY project, the applicability of many countermeasures is being critically assessed using a wide range of criteria. Attention is being given to issues such as practicability, feasibility, capacity and environmental side-effects, as well as social factors such as public perceptions of risk, communication of information and the need for dialogue and consultation with affected communities, and ethical aspects such as informed consent and the fair distribution of costs and doses. Although such socio-ethical factors are now the subject of a substantial field of research, there has been little attempt to integrate them in a practical context for decision makers. Within this paper, we specifically consider the ethical aspects of restoration strategies and suggest practical means by which these can be taken into account in the decision making process, introducing a value matrix. The paper covers two critical areas: evaluation of individual countermeasures, and use of the matrix to ensure transparent and systematic consideration of values in selection of a restoration strategy. 相似文献