Recurrent variations of anomalous oxygen in association with a corotating interaction region

The fluxes of anomalous oxygen (E ranging from 3.5-6.8 MeV/amu), as measured by the EPAC instrument on ULYSSES, show a recurrent variation with the solar rotation period, which is anticorrelated with the fluxes of particles accelerated at the shocks of a corotating interaction region (CIR), and correlated with the fluxes of galactic cosmic rays known to be modulated by the CIR. The amplitude of this variation is much higher than expected for galactic cosmic rays of the same rigidity.     

Reflectance spectroscopy and geochemical analyses of Lake Hoare sediments, Antarctica: implications for remote sensing of the Earth and Mars

Visible to infrared reflectance spectroscopic analyses (0.3-25 micromoles) have been performed on sediments from the Dry Valleys region of Antarctica. Sample characterization for these sediments includes extensive geochemical analyses and X-ray diffraction (XRD). The reflectance spectra and XRD indicate major amounts of quartz, feldspar, and pyroxene in these samples and lesser amounts of carbonate, mica, chlorite, amphibole, illite, smectite, and organic matter. Calcite is the primary form of carbonate present in these Lake Hoare sediments based on the elemental abundances and spectroscopic features. The particle size distribution of the major and secondary components influences their detection in mixtures and this sensitivity to particle size is manifested differently in the "volume scattering" and "surface scattering" infrared regions. The Christiansen feature lies between these two spectral regimes and is influenced by the spectral properties of both regions. For these mixtures the Christiansen feature was found to be dependent on physical parameters, such as particle size and sample texture, as well as the mineralogy. Semiquantitative spectroscopic detection of calcite and organic material has been tested in these quartz- and feldspar-rich sediments. The relative spectral band depths due to organics and calcite correlate in general with the wt% C from organic matter and carbonate. The amounts of organic matter and carbonate present correlate with high Br and U abundances and high Ca and Sr abundances, respectively. Variation in the elemental abundances was overall minimal, which is consistent with a common sedimentary origin for the forty-two samples studied here from Lake Hoare.     

The role of physical-biological coupling in the benthic boundary layer under megatidal conditions: The case of the dominant species of theAbra alba community in the Eastern Baie de Seine (English Channel)

Recent evidence has shown that postlarvae and juveniles of the most dominant species of theAbra alba community of the eastern Baie de Seine are able to re-enter the water column after larval settlement and undergo active and/or passive redistribution. However, few subtidal studies have been conducted to investigate and quantify the processes controlling the abundance of drifting postlarvae and juveniles. The purpose of this study was to verify the reproducibility or the variability of this phenomenon and to assess coupling between the intensity of drifting and that of bed shear stress, which is dependent on tidal currents, wave characteristics, and sediment features. This study was conducted in June and July 1995 at two sites in the bay, one located at the center of the muddy fine-sediment community and the other at its external border with the fine clean sands of theOphelia borealis community. At each site, suprabenthic sledge samples were taken during specific tidal conditions (low tide, slack water, and flood and ebb peaks) during a neap and a spring tide. Physical data (current velocity, turbidity, and suspended matter content) and meiobenthic samples were taken at the same time. Under megatidal conditions, drifting was a quantitatively important dispersal mechanism for at least 15 of the fine-sediment dominant species belonging to various groups such as polychaetes, molluscs (gastropods and bivalves), and echinoderms. The fluctuation in abundance of drifters was related to tidal range, tidal period, location of the site, and the recruitment dynamics. However, species differed strongly in theri response to hydrodynamical parameters. Three types of drifting species were observed: species that were only present in the water column (‘undet. cardiids’ and Mytilidae); species that were both drifting and present at the seaded (Abra alba, Phaxas pellucidus, Eteone picta, Mysella bidentata, Ophiura texturata, Owenia fusiformis, Pholoe minuta, Phyllodoce lineata, Pectinaria koreni, andSpisula subtruncata); species that were present at the seabed but did not drift during the sampling period (Acrocnida brachiata, Eteone longa, Eumida sanguinea, Glycinde normanni, Magelona mirabilis, Nemertean sp1,Nephtys sp.,Spiophanes bombyx, andTubulanus polymorphus). Each drifting pattern is related to eco-ethological species characteristics and may have very different consequences on population dynamics.     

Studies on reaction kinetics in magnetic oxide minerals

Summary Reactions within spinel-type oxides are examined by consideration of (i) the law of mass-action and its limits, (ii) the structural field situation (Mössbaufr) and the (high- or low-) spin state, (iii) the cation site preferences. The conditions for electron transport, cation and vacancy diffusion during oxidation are determined. Effects of defect diffusion on domain-wall mobility and ordering processes during thermal influences are discussed.     

Some results of laboratory investigations of magnetic rock samples (Serpentinites)

Summary In this paper the results ofLauterbach, Jubelt & Others are completed by photomicrographic, thermomagnetic and X-ray investigations. The rock samples consists of antigoritisated serpentinite containing veins. The material of the veins consists of magnetite and -Fe₂O₃. Some crystal physical considerations concerning the process of antigoritisation are represented.

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Zusammenfassung In vorliegender Arbeit wird über ergänzende photomikrographische, thermomagnetische und röntgenanalytische Untersuchungen zu den Ergebnissen vonLauterbach, Jubelt & Mitarbeitern berichtet. Es handelt sich hierbei um antigoritisierten Serpentinit mit eisenoxydhaltigen Zerrklüften. Einige strukturphysikalische Betrachtungen gelten den Antigoritisierungsvorgängen.

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Paper presented at the XII. General Assembly IUGG, Helsinki, 1960, Comitee on Secular Variation and Paleomagnetism.     

Alexander von Humboldts Isothermen

Ohne Zusammenfassung     

Abschätzungen über einige Quellen des atmosphärischen Aerosols

Zusammenfassung Die vonLettau berechnete Produktion von Aitkenkernen durch Großstädte und die Abschätzung über die weltweite Wirkung von Vegetationsbränden und anderen Trübungsquellen werden diskutiert.-Nach gleichzeitigen Sonnenstrahlungsmessungen in und ausserhalb von Großstädten nimmt in der über den Städten befindlichen Luft der TrübungsfaktorT um 4 . 10^–4 sec^–1 zu. Durch Vergleich der Bevölkerungsdichten wird dieser Wert der anthropogenen Trübungsproduktion auf die Trübungszunahme der Luft über grösseren Gebieten umgerechnet. Für drei günstige Hochdrucklagen mit schwachen Winden über Mitteleuropa werden die Strahlungsmessungen von vier Stationen bearbeitet; die beobachtete Trübungszunahme (dT=0.15 bis 0.4 pro Tag) stimmt mit der errechneten gut überein. Die Rauchtrübung durch Vegetationsbrände dürfte im Mittel der Nordhalbkugel etwas geringere Wirksamkeit als Industrietrübung haben. Auf die Wichtigkeit einer Abschätzung der Trübungsproduktion aus der Gasphase, die in wolkenreichen Luftmassen eine wesentliche Rolle spielen dürfte, wird hingewiesen.

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Summary A discussion is given ofLettau's calculation of the Aitken nuclei production by towns and the estimations of the world wide effect of vegetation fires and of other nuclei sources. Sunradiation measurements, made simultanously inside and outside from cities, show that the turbidity factor of the air over towns increases by 4 . 10^–4 per sec. From consideration of the population densities, the value of anthropogeneous turbidity production is calculated for greater areas. Radiation measurements of four stations at high pressure weather situations with weak winds over Europe show a good agreement with the calculations. It seems that the mean turdidity over the northern hemisphere produced by smokes from vegetation fires has not so great effect as anthropogeneous aerosol. The attention is made to the importance of an estimation of the turbidity production from the gaseous phase, that may play an essential role in cloudy air masses.