Accuracy, reproducibility and vertical resolution of data from radiosondes

In a comparison of three radiosonde-systems typical data deviations as well as their reproducibility could be determined. Basic considerations regarding a possible vertical resolution are followed by a suggestion as to how the ascent velocity of the balloon could be utilized to determine vertical winds

Effects of increased begging and vitamin E supplements on oxidative stress and fledging probability

Offspring often use begging displays to demand food from parents. Begging is supposed to be a costly behavior, and oxidative stress is one potential cost of begging. We experimentally manipulated the begging intensity of great tit nestlings and the availability of vitamin E, an important antioxidant. The results suggest that oxidative stress is rather a minor cost of begging. However, nestlings supplemented with vitamin E were more likely to fledg

managing switchgrass for biomass production and summer grazing

"July 2013.""A Thesis presented to the Faculty of the Graduate School at the University of Missouri--Columbia In Partial Fulfillment of the Requirements for the Degree Master of Science."Thesis supervisor: Dr. Robert Kallenbach.Two studies were conducted on established switchgrass plots at Columbia and Mount Vernon, Missouri. The Columbia site was located on Mexico silt loam, and the Mount Vernon site on Viraton silt loam. The first study examined the feasibility of harvesting switchgrass for biomass and summer forage within a season. Yields and forage quality were compared between four harvest management treatments: a single post-frost harvest for biomass, a forage harvest at boot stage followed by a post-frost biomass harvest, biomass harvest at post-anthesis with summer regrowth harvested as forage, and biomass harvest at pre-anthesis with summer regrowth harvested as forage. Summer regrowth was minimal at Mount Vernon due to a fragipan and shallower rooting depth at that site. Regrowth had greater lignin content and as a result, was less digestible. The second study attempted to determine the effect of switchgrass maturity on efficiency of conversion to glucose through enzymatic hydrolysis. These maturity stages included boot stage, pre-anthesis, post-anthesis, full seed, and post-frost. Lignin was not shown to negatively affect efficiency of enzymatic hydrolysis. Rather, hemicellulose was shown to negatively impact conversion efficiency, possibly because acid pretreatment was incomplete and thus some hemicellulose remained in the digested material.Includes bibliographical references

Ultraviolet reflectance of plumage for parent-offspring communication in the great tit (Parus major)

Ultraviolet (UV) reflectance has been implicated in mate selection. Yet, in some bird species the plumage of young varies in UV reflectance already in the nest and long before mate choice and sexual selection come into play. Most birds molt the juvenile body plumage before reaching sexual maturity, and thus, some conspicuous traits of the juvenile body plumage may rather have evolved by natural selection, possibly via predation or parental preference. This second hypothesis is largely untested and predicts a differential allocation of food between fledging and total independence, which is a time period of 2-3 weeks where offspring mortality is also highest. Here, we test the prediction that parents use the individual variation in UV reflectance among fledglings for differential food allocation. We manipulated UV reflectance of the plumage of fledgling great tits Parus major by treating chest and cheek feathers with a lotion that either did or did not contain UV blockers and then recorded food allocation by parents in an outdoor design simulating postfledging conditions. The visible spectrum was minimally affected by this treatment. Females were found to feed UV-reflecting offspring preferentially, whereas males had no preference. It is the first evidence showing that the UV reflectance of the feathers of young birds has a signaling function in parent-offspring communication and suggests that the UV traits evolved via parental preferenc

Partial incubation and its function in great tits (Parus major)—an experimental test

In many bird species, females incubate the eggs for short periods before clutch completion. The role of such partial incubation and the effective egg temperatures attained are controversial. Possible functions depend on whether temperatures reach the critical values required for embryogenesis and include the protection of the clutch from predators, brood parasites, and environmental factors; inhibition of bacterial growth on eggs; control of hatching asynchrony; or energy saving by parents. In this study, in a natural population of great tits, we first investigated the occurrence and extent of partial incubation, and second, we evaluated some potential functions by experimental simulation of the observed patterns of partial incubation. We found that egg temperatures during partial incubation were clearly raised above the physiological zero temperature for embryo development. Simulation of partial incubation did not affect any breeding parameters or nestling morphological traits compared with controls. It suggests that partial incubation with temperatures above the minimum temperature for embryo development does not serve to increase the variation in nestling morphology and thus competitiveness, in particular, does not increase hatching asynchrony within brood as one of its currently most discussed function

Environmental Risk Assessment of Chemical Substances

According to the OECD, it is estimated that some 70000 synthetic chemicals are in daily use. This number is still growing. Some of these products (e.g. polychlorinated biphenyls or chlorofluorocarbons) have gained great public attention due to their unexpected undesirable long-term impact on the ecosystem. The industrialized nations have therefore implemented and enforced stringent laws, in order to control the use of potentially harmful substances.It is an almost impossible task to have the EU Base Set available for all existing substances. The EU and other organizations like OECD have therefore put together priority lists of potentially harmful high-volume chemicals which are assessed by experts. The last couple of years, a tremendous amount of work has been done to develop computer-based modeling systems to predict the environmental behavior and distribution of chemical substances.There are models around (e.g. Mackay, USES, TGD EU, and others) to describe environmental distribution (Predicted Environmental Concentration (PEC)) of nonionic and nonpolar substances. For a first assessment, only a few physical properties (MP, BP, SOL, and possibly pKa) are needed. For ionic and/or polar substances, expert know-how is required.For environmental toxicity (Predicted No Effect Concentration (PNEC)), however, the situation is far more complex. There are different modes of action for each trophic level (algae, crustacea, fish). Computer models with Quantitative Structure-Activity Relationship (QSAR) offer a scientifically attractive tool to predict aquatic toxicity and biodegradation. There are no models that are applicable to heterogeneous chemical classes without expert know-how. Further progress can therefore be expected.The result of an ERA for perchloroethylene with USES is presented, and the problems of the adequacy of the model parameters explained. Here too, a further improvement is addressed.QSARs are attractive tools to design products with improved environmental compatibility at the research stage even before the first synthesis. In order to achieve such an ambitious aim, QSAR models that also include expert rules and evaluated results and their dependence on molecular structures will have to be further developed