Zur Ökologie des Brachsen (Abramis brama (L.)) im Bodensee

The reactions of the bream,Abramis brama, to the ecological changes due to man-made eutrophication of Lake Constance were investigated. It could be demonstrated that the bream adapted only to a negligible amount. Likely due to its largeness, structure of the body and population composition the bream is more conservative than perch, roach and whitefish. The only reactions to the changed environment are modificated vertical and horizontal distribution and partly plancton feeding in summer.      

Natural analogues for the transuranic actinide elements: An investigation in Minas Gerais,Brazil

A highly weathered deposit of thorium and rare earth elements located near the summit of a hill in the state of Minas Gerais, Brazil, is being studied as an analogue for a radioactive waste repository that sometime in the distant future may be eroded to the surface or intruded by groundwater Thorium serves as an analogue for Pu⁴⁺, and La³⁺ as an analogue for Cm³⁺ and Am³⁺ The mobilization rate constants of the analogue elements by groundwater are so slow (of the order of 10⁻⁹ per year) as to suggest that essentially complete radioactive decay of the transuranic actinides would occur in place even under the relatively unfavorable conditions that exist at a site such as this     

New active galactic nuclei science cases with interferometry

Infrared (IR) interferometry has made widely recognised contributions to the way we look at the dusty environment of supermassive black holes on parsec scales. It finally provided direct evidence for orientation-dependent unification of active galaxies, however it also showed that the classical “torus” picture is oversimplified. New scientific opportunities for AGN have been suggested, and will soon be carried out, focusing on the dynamical aspects of spectrally and spatially resolved interferometry, as well as the potential to employ interferometry for cosmology. This will open interferometry to new scientific communities.     

On singularities in electrodynamics and gravitational theory

The singularity and particle problems in electrodynamics and gravitational theory are discussed. Comparing different modifications of MAXWELL 's electrodynamics and general theory of relativity, arguments are given which show possibilities of solving these problems by a modification that replaces EINSTEIN 's equations by those of the EINSTEIN -BACH -WEYL -type.     

Electromagnetic induction fields in the deep ocean north-east of Hawaii: implications for mantle conductivity and source fields

Summary. We have analysed a thirty-six day recording of the natural electric and magnetic field variations obtained on the deep ocean floor north-east of Hawaii. The electromagnetic fields are dominated by tides which have an appreciable oceanic component, especially in the east electric and north magnetic components. The techniques of data analysis included singular value decomposition (SVD) to remove uncorrelated noise. There are three degrees of freedom in the data set for periods longer than five hours, indicating a correlation of the vertical magnetic field and the horizontal components, suggesting source field inhomogeneity. Tensor response functions were calculated using spectral band averaging with both SVD and least squares techniques and rotated to the principal direction. One diagonal component, determined mainly by the north electric and east magnetic fields, is not interpretable as a one-dimensional induction phenomenon. The other diagonal term of the response function indicates a rapid rise in conductivity to 0.05 mho m⁻¹ near 160 km. No decrease in conductivity below this depth is resolvable. Polarization analysis of the magnetic field indicates moving source fields with a wavelength near 5000 km. Model studies suggest that the two dimensionality in the response function may be caused by motion in the ionospheric current system.     

Sulfur dioxide and other cloud-related gases as the source of the microwave opacity of the middle atmosphere of Venus

Spacecraft radio occultation measurements imply the presence of a nonuniformly mixed gaseous absorber within, but mostly below, the main cloud layer of sulfuric acid—water droplets measured by Pioneer-Venus. Preliminary considerations of the amount, distribution, and effects of sulfur dioxide and other gases, which apparently are associated with and produce the cloud, indicate that they constitute an important, and probably the predominant, source of the observed microwave opacity of the middle atmosphere of Venus.     

Seasonal dynamics of CO2 profiles across a soil chronosequence,Santa Cruz,California

Concentrations of CO₂ in soil atmosphere and CO₂ efflux were measured across a marine terrace soil chronosequence near Santa Cruz, California. Soil development, specifically the formation of an argillic horizon, has created a two-tier soil gas profile in the older terrace soils. The soil above the argillic horizon has seasonal variations in soil CO₂ associated with plant respiration. The older soils with dense argillic horizons maintain a year round ～1%CO₂ below the argillic horizon. The CO₂efflux during the growing season is higher on the older terraces.     

Deriving Star Formation Histories: Evolutionary or Population Synthesis Codes versus Color-Magnitude Diagrams

The goal of this project is to analyze the integrated-light spectrum of a region in the LMC bar, for which HST images are already available yielding color-magnitude diagrams reaching the oldest main-sequence turnoff. Then, we can derive the star formation history in this field through evolutionary/population synthesis of the integrated light from 330 to 990 nm by a variety of independent methods and compare the results with the - in principle - more reliable results derived from the analysis of the color-magnitude diagram (CMD). This confrontation is the key ‘truth-test’ needed for the understanding of the abilities and the limitations of the evolutionary/population synthesis methods that must be applied of necessity to unresolved nearby and far-away galaxies. We report here on the observational part of the project. This revised version was published online in September 2006 with corrections to the Cover Date.