Die Nervenleitung als Wechselwirkungseffekt

The Science of Nature -     

Eine Bemerkung zu den Quadrupolmomenten der Atomkerne

The Science of Nature -     

Recycling von Straßenkehricht

Waste recycling is provided by law, e.g. the German ‘Kreislaufwirtschafts- und Abfallgesetz’. Even street sweepings can be recycled, e.g. as winter grit. But if street sweepings are repeatedly brought back on street, toxic agents as heavy metals can accumulate. What is the amount of heavy metal load? Regarding this, is it possible to recycle street sweepings? Is it possible to reduce heavy metal load with the smallest size fraction (the highest load being assumed in) is treated as disposal? Are these fractions actually highest loaded? These questions have been the framework of two studies elaborated at Schleswig-Holstein’s State Authority of Nature Protection and Environment (LANU) based on samples from cities in German state Schleswig-Holstein, particularly from its capital city Kiel. Threshold values for that very purpose do not exist in Germany. But a working group of all German states (called LAGA) suggested some approximate values for recycling of waste and other remainder0materials; the values have been fixed in state of law in Schleswig-Holstein. Our evaluation is oriented towards them. The samples taken in autumn 1998 and winter 1999 were devided in three fractions, the amount of heavy metal measured for each fraction with an ICP-AES. Normal disintegration for that purpose is aqua regia. In this case study nitric acid had been used dissolving just a part of heavy metal concentration although it is not a standard method. It is assumed that it better simulates the natural solubility, and additionally, it is less costly. Therefore we insistently recommend to discuss the application of this method. Samples taken in autumn were higher loaded than those taken in winter. It is worth of special remark that there are high values for zinc, copper, and lead in autumn samples. Regarding above mentioned approximate values samples taken in winter can be assessed for recycling, whereas samples taken in autumn were loaded too high. The finest fraction (<0.5 mm) of samples taken in winter were highest loaded as expected. Therefore the heavy metal concentration could be reduced if this fraction would be treated as disposal. The same can not be assumed for samples taken in autumn, probably due to the higher amount of organic matter.     

Pup guarding by greater spear-nosed bats

Alloparental care poses an evolutionary dilemma because effort is expended on non-filial offspring. Thus, instances of alloparental care have been attributed to either mistaken identity, (i.e., recognition errors) or active cooperation. In greater spear-nosed bats (Phyllostomus hastatus), reproductive females roost together in stable long-term social groups in cave ceilings. Non-volant pups frequently fall from roost sites to the cave floor where they can die unless retrieved by an adult. In this study, we examined the function of adult female visits to non-filial young and tested whether visits were attributable to recognition errors or to cooperation. We found that females visited non-filial pups from their own social group more than expected. Females from different social groups attacked and sometimes killed pups, and male pups were attacked more frequently than female pups. Visits by group mates benefited fallen pups by reducing the likelihood of attack by females from other groups. In contrast to the mistaken identity hypothesis, we found that some females leave their own pups to approach and remain with group mates’ pups. We used microsatellite markers to estimate relatedness and test whether kinship could explain this alloparental care and found that females were unrelated to the pups they guard. We conclude that females who reside in highly stable social groups exhibit cooperative behavior that cannot be explained by kinship and is unlikely to be due to direct or generalized reciprocity. Instead, our data suggest that alloparental care likely involves a complex interplay between group membership and cooperative foraging.     

Predicting constant decay rates of coarse woody debris—A meta-analysis approach with a mixed model

The aim of the study is the estimation of decay rates for coarse woody debris in large forest regions. These rates, together with estimations of the amount of deadwood, can be used to calculate the release of carbon from that pool into the atmosphere. The model can be used for predictions of decomposition rate constants in a wide range of forest areas (e.g. in process based ecological models, reporting of GHG-emissions), as only easily available predictor variables were used in the regression.Based on an intensive literature research a meta-analysis on influencing factors controlling the constant decay rate of coarse woody debris was set up. The included studies differed significantly in the survey methods as well as in the geographical origin. 39 studies were collected, 30 appeared in North America and nine in Europe. Based on these studies 291 observations of the remaining fraction of coarse woody debris were collected.To quantify the effects that influence the decomposition rates a nonlinear mixed effects model was constructed. Only physiologically interpretable variables were included. With this approach it was possible to determine influencing effects from mean temperature in July, annual rainfall (as quadratic term), diameter of woody material and grouping into hardwoods or conifers and mass- or density loss were significant variables. The mixed effects model also allowed an estimation of the species-specific effects on the decomposition process. These random effects are given for 42 tree species. The degrees of freedom were used efficiently. The model explains 79.6% of the variance and is superior to a comparable multiple regression model.     

Public mosquito abatement

Mosquito abatement is a public good for which there is a long history of operating expenditures and measured performance. A simultaneous model of mosquito abundance and abatement response is developed. Parameters are estimated using time-series, cross-section data from 30 districts. Both insecticides and ditching have contributed to reduced mosquito populations. There is evidence that district managers may have invested in excess permanent control (ditching) relative to use of insecticides, and that present abatement expenditures for the average district are excessive.     

Stakeholder perspectives on the value proposition of enterprise-level natural capital accounting for three primary industries

Environment Systems and Decisions - Globally we are experiencing a decline in aggregate natural capital. Many primary industries and enterprises are highly dependent on renewable and non-renewable...     

From metamorphosis to maturity in complex life cycles: equal performance of different juvenile life history pathways

Performance in one stage of a complex life cycle may affect performance in the subsequent stage. Animals that start a new stage at a smaller size than conspecifics may either always remain smaller or they may be able to "catch up" through plasticity, usually elevated growth rates. We study how size at and date of metamorphosis affected subsequent performance in the terrestrial juvenile stage and lifetime fitness of spadefoot toads (Pelobates fuscus). We analyzed capture-recapture data of > 3000 individuals sampled during nine years with mark-recapture models to estimate first-year juvenile survival probabilities and age-specific first-time breeding probabilities of toads, followed by model selection to assess whether these probabilities were correlated with size at and date of metamorphosis. Males attained maturity after two years, whereas females reached maturity 2-4 years after metamorphosis. Age at maturity was weakly correlated with metamorphic traits. In both sexes, first-year juvenile survival depended positively on date of metamorphosis and, in males, also negatively on size at metamorphosis. In males, toads that metamorphosed early at a small size had the highest probability to reach maturity. However, because very few toadlets metamorphosed early, the vast majority of male metamorphs had a very similar probability to reach maturity. A matrix projection model constructed for females showed that different juvenile life history pathways resulted in similar lifetime fitness. We found that the effects of date of and size at metamorphosis on different juvenile traits cancelled each other out such that toads that were small or large at metamorphosis had equal performance. Because the costs and benefits of juvenile life history pathways may also depend on population fluctuations, ample phenotypic variation in life history traits may be maintained.