Photo-Akustik-Spektroskopie an festen Stoffen

A short historic introduction into the subject and the basics of the generation of a photoacoustic signal with the emphasis upon the particularities of solid samples are given. The set-up of a two-beam photoacoustic spectrometer is described. For a better understanding of the investigations of solid samples the basic theory is presented. Specially treated subjects are: the saturation effect and how to overcome it; depth profiles of thin layers as a nondestructive method used in the investigation of a green leaf and a sheet of color reversal paper; the investigation of solid solutions in a polymer matrix with the determination of the thermic data of the matrix itself, and the fluorescence quantum yield of organic dyes solved therein. Finally a summary of numerous other applications of the PAS is given.     

The influence of chlordecone and oestrogen on the secretion of proteinaceous molecules of the mouse uterus

Ovariectomised mice were treated with sesame seed oil, oestradiol, or one of three different levels of the insecticide chlordecone (1, 1a, 3, 3a, 4, 5, 5a, 6-decachloro-octahydro-1, 3, 4-metheno-2H-cyclobuta[cd] pentalen-2-one). After 9 days of treatment, the uteri were injected with (35)S-methionine and radiolabelled proteins were flushed from uteri 4 h later. Reproductive tract weights and the total amount of radioactivity in uterine flushings were measured. Reproductive tract weights increased significantly only in animals treated with the highest dose of chlordecone tested and oestradiol-treated animals. Trichloroacetic acid (TCA) precipitated radioactivity was increased by all doses of insecticide chlordecone tested but increases were significant only at one level. The greatest stimulation of (35)S-methionine incorporation occurred in ovariectomised animals treated with oestradiol. Radioactive proteins were analysed by fluorography of two-dimensional gels. The fluorograms showed that the proteinaceous uterine secretions, as influenced by chlordecone, were greatly reduced in number as compared with those secreted under the influence of oestradiol. Chlordecone appears to cause the secretion of proteinaceous material from the uteri of mice in a qualitatively different manner than does oestradiol.     

Testing the evolution of increased competitive ability (EICA) hypothesis in a novel framework

The "evolution of increased competitive ability" (EICA) hypothesis proposes that escape from natural enemies, e.g., after transcontinental introductions, alters the selection regime because costly defenses no longer enhance fitness. Such an evolutionary loss of defenses enables resources to be directed toward growth or other traits improving performance. We tested the EICA hypothesis in a novel framework in which the natural enemy is the traveler that follows its widespread host by accidental or deliberate (biocontrol) introductions. In a greenhouse experiment we used populations of Senecio vulgaris from North America, Europe, and Australia that differ in the history of exposure to the rust fungus Puccinia lagenophorae. Contrary to what is predicted by EICA, we found no evidence for increased levels of resistance to the rust fungus in plant populations with a longer history of rust exposure (Australia). Similarly, there was no evidence for reduced fecundity in these populations, although vegetative vigor, measured as secondary branching and growth rate, was lower. The maintenance of high rust resistance in populations with no (North America) or only a short history (Europe) of rust exposure is surprising given that resistance seems to incur considerable fitness costs, as indicated by the negative association between family mean resistance and fitness in the absence of disease observed for all three continents. The comparison of population differentiation in quantitative traits with estimates of differentiation in amplified fragment length polymorphic (AFLP) markers suggests that a number of fitness-related traits are under divergent selection among the studied populations. The proposed framework to test changes in the evolutionary trajectory underlying EICA can be employed in an expanded range of systems. These may include investigations on a cosmopolitan weed or crop when an antagonist is expanding its geographic range (such as our study), studies along a chronosequence of introduction time with expected increasing accumulation of natural enemies over time, or comparisons between introduced plant populations that differ in exposure time to biocontrol organisms.     

Walking in “wild” and “tended” urban forests: The impact on psychological well-being

The positive effect of natural compared to urban environment on human restoration and well-being has been proved in various studies. To go one step further in analyzing the influence of physical environments, we question if this positive effect is consistent in different natural conditions namely wild and tended urban forests. In an experimental field setting, participants were randomly assigned to either a walk through wild or tended forests for 30 min. Multidimensional scales in a pre-post-treatment-setting measured well-being. Results indicate a stronger change in “positive affect” and “negative affect” in the tended forest condition. Well-being factors “activation” and “arousal” changed after solitary walks, too. However, there were no differences between the treatment conditions, indicating a stronger influence of physical activity than the forest condition wild and tended on these well-being factors. Perceived attractiveness of the natural area did not effect the change in well-being, thus questioning the close relation between perceived attractiveness and the effect on well-being suggested in prior research. Furthermore, more and less fatigued persons did not profit differently concerning well-being changes. The results give important advice to design natural areas serving restoration and public health, especially for people living in urban environments.