Reply to discussion of “The Azuara impact structure (Spain): new insights from geophysical and geological investigations” by K. Ernstson and J. Fiebag     

Kord Ernstson  Johannes Fiebag 《International Journal of Earth Sciences》1993,82(4):756-759

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Blockage of regional seismic waves by the Teisseyre-Tornquist zone   总被引：1，自引：0，他引：1  

Johannes Schweitzer 《Geophysical Journal International》1995,123(1):260-276

During the Group of Scientific Experts Technical Test (GSETT, second experiment, 22 April-2 June 1991), several hundred seismic events were located in Europe. Associating these events with the detecting stations-altogether 28 European stations including seven arrays participated in the GSETT-2 experiment-clearly shows that the Teisseyre-Tornquist Zone (TTZ) influences the propagation of regional seismic phases. Large explosions in the Bay of Gdańsk, for example, were observed by the well-established Scandinavian arrays'NORSAR (Δ 830km) and ARCESS (Δ 1650km), but not by the Polish station KSP (Δ 470km) nor by the new highly sensitive GERESS array (Δ 750km), both situated south-west of the TTZ. For events in central Europe with comparable magnitudes, we observe a similar increase of the detection threshold at stations located north-east of the TTZ in Scandinavia. to explain these observations, the wave propagation of P_n and P_g perpendicular to the TTZ was modelled for a profile from the Estonian/Russian border region to GERESS with Gaussian-beam seismograms. Published crustal and uppermost mantle models for Poland and for Europe were used as a starting point for developing a model of the TTZ. the observations cannot be explained only by a graben-like crustal structure with a jump in Moho depth from 30km to 50km. to defocus the seismic energy, the TTZ as a structural anomaly between eastern and western Europe must reach down into the upper mantle to a depth of at least about 200 km. the proposed model has such a deep-reaching root of the TTZ.  相似文献   

Hydrophobic and electrostatic parameters in bacterial adhesion   总被引：5，自引：0，他引：5  

Mark C. M. van Loosdrecht  Willem Norde  Johannes Lyklema  Alexander J. B. Zehnder 《Aquatic Sciences - Research Across Boundaries》1990,52(1):103-114

Recently it has been shown that the initial stages of bacterial adhesion to a model-surface of sulphated polystyrene can best be described using hydrophobic and electrostatic parameters. In the present study it is tested whether these parameters can generally be applied to predict bacterial adhesion by using (i) glass, as a model for hydrophilic and natural surfaces of silicates and oxides, (ii) polystyrene coated with proteins, as a model for a surface coated with an organic layer, and (iii) river Rhine sediment, as an example of a natural surface. Adhesion to glass was dominated by electrostatic interaction, whereas adhesion to polystyrene coated with various types of proteins depended on the surface characteristics of the bacteria and the type of protein. By relating Van der Waals interactions to hydrophobicity of the interacting species, the adhesion of bacteria to the various surfaces including the river Rhine sediments could be interpreted in terms of the DLVO-theory. It is therefore concluded that the conceptual principles of the DLVO-theory (interplay of Van der Waals and electrostatic interactions) are suitable to describe, at least qualitatively, the initial processes of bacterial adhesion to a wide range of surfaces.  相似文献   

The system CaO-Al2O3-SiO2-H2O: new phase equilibria data,some calculated phase relations,and their petrological applications     

Niranjan D. Chatterjee  Wilhelm Johannes  Hans Leistner 《Contributions to Mineralogy and Petrology》1984,88(1-2):1-13

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Nitrogen isotopes in the solar system     

Johannes Geiss  Peter Bochsler 《Geochimica et cosmochimica acta》1982,46(4):529-548

Measurements of the isotopic composition of nitrogen in the solar system are summarized. We show that the 30% change, during the last 3 to 4 billion years, of ${}^{15}\text{N}{}^{14}\text{N}$ in solar-wind-bearing lunar soils and breccias probably does not reflect changes in this ratio at the solar surface. Such changes, whether by spallation or thermonuclear reactions are ruled out by comparing the yields of ¹⁵N with those of other rare isotopes such as ⁹Be, ¹¹B, ³He or ¹³C, even if an arbitrary degree of solar mixing is introduced. Moreover, we calculate that the solar activity required for producing significant amounts of ¹⁵N by spallation at the solar surface should have resulted in a particle bombardment of the Moon of an intensity that would have produced amounts of spallation isotopes (e.g.¹⁵N, ²¹Ne, ³⁸Ar, ¹³¹Xe) several orders of magnitude in excess of what is actually found in the whole regolith.We argue that accretion of interstellar matter also does not work as a cause for a significant change of the photospheric ${}^{15}\text{N}{}^{14}\text{N}$ ratio. Evidence is presented that the mixing depth at the solar surface on a time scale of ?10⁹ years is (10^?2 ?10^?1) M_⊙ Mixing to this depth renders accretion of interstellar matter as a source of compositional changes at the solar surface inefficient, even if allowance is made for the expected large difference in the accretion rates of condensed and gaseous matter. A quantitative treatment of several alternatives of solar accretion leads to serious contradictions (e.g. with the low Ne abundances in planetary atmospheres or with the amounts of nitrogen that should have been directly accreted by the Moon), and we conclude that accretion during the main sequence life of the Sun is an unlikely source of changes in ${}^{15}\text{N}{}^{14}\text{N}$ at the solar surface.A ratio of ${}^{15}\text{N}{}^{14}\text{N}\text{= (4.0 ± 0.3) × 10}{}^{\mathrm{?3}}$ is our best estimate for average solar system material and for the Sun. We propose that a rare, very light nitrogen component (called LPN) is admixed in varying amounts to planetary matter. Undiluted LPN has not been found in meteorites or planetary atmospheres, but we show that the combined effects of LPN admixture and isotope fractionation can in principle account for the variability of ${}^{15}\text{N}{}^{14}\text{N}$ observed in the planetary system. Determination of the Jovian ${}^{15}\text{N}{}^{14}\text{N}$ ratio with an accuracy of ~10% would crucially test our interpretation of the nitrogen isotope observations.  相似文献   

The radio frequency dielectric properties of the stratified UG1–UG2 geological unit in the Bushveld Complex     

Marc Rütschlin  Johannes H. Cloete  Iain M. Mason  Keith D. Palmer   《Journal of Applied Geophysics》2007,62(4):354-360

A new measurement technique enables the complex dielectric properties of the geological strata comprising the UG1–UG2 (Upper Group 1–Upper Group 2) unit of the Bushveld Complex in South Africa to be determined with unprecedented detail at radio frequencies (RF). Results of non-destructive laboratory measurements of representative diamond drill core samples from the UG1–UG2 unit are presented at 25 MHz. These data establish that the UG1 and UG2 chromitite layers are embedded in rock strata (norite, pyroxenite and anorthosite) which are translucent in the HF spectral band, whereas the chromitite layers themselves exhibit significant velocity contrast, making them good radar reflectors. The data presented here is useful for calibration of the radar system, and for predicting the range and resolution performance of borehole radars operating in both the hanging and footwalls of the economically important platiniferous UG2 reef.  相似文献   

Variability in fluxes of nutrients (N,P, Si) into the North Sea from the Atlantic Ocean and skagerrak caused by variability in water flow     

Remi W. P. M. Laane  Einar Svendsen  Günther Radach  Gerard Groeneveld  Peter Damm  Johannes PÄtsch  D. S. Danielssen  Lars FØyn  Martin Skogen  Marek Ostrowski  Kees J. M. Kramer 《Ocean Dynamics》1996,48(3-4):401-419

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Die Kattegat-Rinne. Erläuterungen zu einer neuen Tiefenkarte     

Dr. Johannes Ulrich  Alfred Eisele 《Ocean Dynamics》1993,45(1):15-29

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Determination of magnitude by use of seismographs recording ground velocity     

Christian Teupser  Johannes Stelzner 《Pure and Applied Geophysics》1969,72(1):72-75

Summary Two electromagnetic seismographs HSJ-I, which are coupled with short-period galvanometers, record the velocity of the ground motion in the range of periods from 0.3 to 20 s in the seismological station Moxa. In this way the magnitude of an earthquake can be calculated without respect to the period of the ground motion. The results of such a determination of magnitudes are compared with those reached in the usual manner from short and long-period seismographs recording the ground displacement.Publication No. 45 of the Institut für Geodynamik, 69 Jena (DDR), Burgweg 11, der Deutschen Akademie der Wissenschaften zu Berlin, Forschungsgemeinschaft. Presented at the IUGG-Assembly, Zurich 1967.  相似文献   

Georg von Neumayer (1826 bis 1909) und das 1. Internationale Polarjahr 1882/1883     

Johannes Georgi 《Ocean Dynamics》1964,17(6):249-272

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