Navigation mit Duftkarte und Sonnenkompaß: Das Heimfindevermögen der Brieftauben

Pigeon homing, investigated as a paradigmatic example of bird navigation, appears to be based on two mechanisms of orientation whose functions correspond to those of map and compass. Tasks of the latter are usually accomplished by a sun compass, taking into account the sun's movement and time of day. Under overcast skies, the magnetic field of the earth may be used for compass orientation. The "map" part of the system, responsible for site localization, makes use of olfactory perception of atmospheric trace compounds, which must be concluded to contain positional information in unfamiliar areas up to several hundreds of kilometers from home.     

Managing environmental quality at the enterprise: the role of project management

An exploratory field study conducted in Europe and the U.S. examines the challenges of managing environmental quality at the enterprise level. The results show that effective environmental quality management depend to a considerable degree on the ability to deal with the multidisciplinary organizational, technical, social, and cultural issues involved in the integration of environmental cost accounting at the enterprise level. The study suggests that the tools and techniques of modern project management can provide an important framework for developing and implementing environmental quality control systems. The recommendations put considerable emphasis on the human side, focusing on the criteria under which environmental quality is best achievable. Strong senior management leadership, people skills, organizational linkages, and alliances, all are critical for dealing with the complexities of managing responsibly toward sustained developments in today’s organizations.     

Biochemistry of lignification

The complete set of enzymes that catalyze the reactions from l-phenylalanine to substituted cinnamyl alcohols is now known. The latter compounds are the primary building stones of lignin. The individual reactions and the possible modes of regulation of this pathway are discussed. The polymerization of cinnamyl alcohols to lignin is mediated by peroxidase. The significance of cell-wall-bound peroxidases in this process and the origin of hydrogen peroxide are reviewed. Finally, the possible role of lignification in relation to disease resistance is discussed.     

Social Rank, Stress, Fitness, and Life Expectancy in Wild Rabbits

 Wild rabbits of the two sexes have separate linear rank orders, which are established and maintained by intensive fights. The social rank of individuals strongly influence their fitness: males and females that gain a high social rank, at least at the outset of their second breeding season, have a much higher lifetime fitness than subordinate individuals. This is because of two separate factors: a much higher fecundity and annual reproductive success and a 50% longer reproductive life span. These results are in contrast to the view in evolutionary biology that current reproduction can be increased only at the expense of future survival and/or fecundity. These concepts entail higher physiological costs in high-ranking mammals, which is not supported by our data: In wild rabbits the physiological costs of social positions are caused predominantly by differential psychosocial stress responses that are much lower in high-ranking than in low-ranking individuals. Received: 23 February 1999 / Accepted: 17 March 1999     

Specific floater home ranges and prospective behaviour in the European starling,<Emphasis Type="Italic"> Sturnus vulgaris</Emphasis>

In many bird species, floaters are present on the breeding grounds in one or more years before they breed. There is increasing evidence that they have specific home ranges in which they search for information about current and future breeding opportunities. We investigated the role of prospecting in a migratory European starling (Sturnus vulgaris) population. Radio-tracking showed that male starling floaters use specific home range areas during the breeding period. Nest-box observations demonstrated that non-parental nest intrusion is common in the starling and that it is significantly more frequent during the nestling than during the incubation period. In addition, small groups of nest boxes were more likely to be occupied by starlings if they had been put up during the preceding breeding season. The results suggest that floaters try to acquire information about local breeding communities. One specific type of information may be the location of potential breeding sites.     

波罗的海的有害物质管理:成果与挑战

能够在生物体内累积的、具有持续性和毒性的有害物质流入波罗的海是一个重要的涉及环境和人类健康的问题.为解决这一问题,主要在赫尔辛基委员会(HELCOM)之下进行了多方努力.本文对HELCOM在有害物质方面所作的努力进行了考查,并讨论了将来在有害物质管理方面面临的挑战.本文认为,尽管还有一些遗留问题和困难需要解决,但过去在控制有害物质方面所做的工作已在改善波罗的海环境质量和减少影响人类健康的风险方面起到了积极的作用.特别是确定了今后HELCOM在对有害物质的管理中面临的四个挑战并对其进行了论述,它们是[1]需要进一步执行并加强公、私部门的能力;[2]需要提高该地区及国际论坛中资料的可用性、质量和可比性;[3]需要巩固现有法规并编入新的问题;[4]需要有效协调HELCOM的活动与其它国际论坛为控制有害物质所做的努力之间的关系.