Periodic orbits in strong bars

The aim of the present investigation has been to investigate numerically the orbits of particles in the gravitational field of barred galaxies for different models of such formations; with special attention to the families of direct periodic orbits in the co-rotating frame.     

Buchbesprechungen

Ohne Zusammenfassung     

The Würmian Late-glacial in Iowland Switzerland

A synthesis is provided of Late-glacial (14-9 ka BP) environmental changes in lowland Switzerland (the ‘Swiss Plateau’). The chronology of deglaciation and subsequent developments in vegetation cover in the area are summarised. The sequence of climatic variations experienced in the region during the Late-glacial is then described and a curve representing the main palaeotemperature variations is presented.     

Ergebnisse bisheriger Abklärungen über die systematische Beziehung zwischen Sommeralbeli und Winteralbeli (Coregonus lavaretus (L.)) im Walensee

A whitefish population considered to consist of two morphologically similar subpopulations is analyzed. Since a reproductive barrier existing earlier between the two subpopulations has lost its effectiveness, only one population exists today, having a very long reproductive period.      

Two new methods for solving large scale least squares in geodetic surveying computations

This paper considers the solution of linear least squares problems arising in space geodesy, with a special application to multi-station adjustment by a short arc method based on Doppler observations. We recall briefly the widely used second-order regression algorithm due to Brown for reducing the normal equations system. Then we propose two algorithms which avoid the use of the normal equations. The first one is a direct method that applies orthogonal transformations to the observation matrix directly, in order to reduce it to upper triangular form. The solution is then obtained by backsubstitution. The second method is iterative and uses a preconditioned conjugate gradient technique. A comparison of the three procedures is provided on data of the second European Doppler Observation Campaign (EDOC-2).     

Etude pedogenetique et isotopique des neoformations de calcite dans un sol sur craie: Caracteristiques et origines

Cryoturbated facies are found at the boundary between soil horizons and Cretaceous chalk. Several types of secondary calcite appear in soil horizons: orange coloured and rounded (partially dissolved) nodules, deeply coloured angular aggregates, transparent isolated rhombs and polycrystalline nodules, needles. The carbon and oxygen isotope compositions of these calcites are correlated: δ¹³C = 4.9δ¹⁸O_PDB + 15.9End members of this correlation are the orange rounded nodules (δ¹³C ? + 8%., $\text{δ}{}^{18}\text{O ? ?1.5‰}$) and the transparent angular polycrystalline nodules (δ¹³C ? ?13; δ¹⁸O ? ?6).Partially dissolved nodules have formed under periglacial climatic conditions. Crystallisation would have occurred under the following (equilibrium) environmental conditions: δ¹⁸O_SMOW (soil solution) ?7, δ¹³C (gaseousCO₂) ? ?5.2, t ? ?2°C. Soil solution was enriched in ¹⁸O by evaporation and atmospheric CO₂ was enriched in ¹³C as compared to present day. Transparent polycrystalline nodules are compatible with present day environmental conditions: δ¹⁸O (soil solution) ranging from ?9 to ?4 and δ¹³C (soil CO₂) ranging from ?24.5 to ?23. These nodules crystallize between May and October at soil temperatures ranging from 10 to 25°C, from evaporated soil solutions. Angular coloured aggregates may form under present day winter conditions for temperatures between 0 and 10°C. However they may also result from present accretion of fragments of periglacial nodules.All recent secondary calcite results from CO₂ degassing and evaporation of soil solutions. Degassing is controlled by the gradient of CO₂ partial pressure within the soil profile. During winter this gradient is low and the resulting calcite precipitation is not significant. During summer a large difference in pCO₂ appears between the root zone and deep soil horizons. The degassing accounts for an increase of about 2‰ in δ¹³C of the total dissolved inorganic carbon and of the related solid carbonate. Evaporation is the main driving force for secondary calcite precipitation.     

Six years of regular ozone soundings over Switzerland

Summary The mean vertical ozone distribution as a function of season is computed from almost 6 years of regular soundings (three times per week) over Switzerland. By comparing the concurrent mean values of the total amount with the 35-year average at Arosa, and by using the correlation between ozone concentration at different levels with the total amount, adjusted values for the seasonal variation of the vertical ozone distribution are obtained which are thought to give a better representation of the long-term climatological mean. The data show a prominent biennial variation of the ozone content around the level of the maximum concentration which does not, however, show up in the total amount because it is missing in the lower stratosphere.