Stability properties for encounterless self-gravitational stellar gas and plasma     

M. R. Feix  J. P. Doremus  G. Baumann 《Astrophysics and Space Science》1971,13(2):478-495

The stability properties of the collisionless plasma and encounterless stellar gas described by the Vlasov equations are studied. The introduction of the multiple Water Bag model allows, for one-dimensional plane geometry, a treatment of the general case and removes some of the difficulties connected with the formulation of the energy variation. From this last result it can be deduced that both plasma and stellar systems steady state described by a monotonically decreasing distributionF() are stable. The demonstration is extended to the spherically symmetric case for self-gravitating gas. Next the constraint of a monotonically decreasingF() is relaxed and it is supposed that the instability appears through the point =0. This is known to be true for some type of plasma instabilities (two streams) but is a simple working hypothesis in the gravitational case. For this marginal mode theN bags equations degenerate into a single wave equation and the stability of the system is given by the sign of the eigenvalues of a Schroedinger type operator. A simple physical picture is obtained for the plasma case where the quantitity (dF/d) dV (the square of the local maximum wavenumber of instability) is introduced. A virtual variation of this quantity indicates if the initial steady state was stable or unstable.  相似文献   

Environmental heterogeneity predicts species richness of freshwater mollusks in sub-Saharan Africa     

T. Hauffe  R. Schultheiß  B. Van Bocxlaer  K. Prömmel  C. Albrecht 《International Journal of Earth Sciences》2016,105(6):1795-1810

Species diversity and how it is structured on a continental scale is influenced by stochastic, ecological, and evolutionary driving forces, but hypotheses on determining factors have been mainly examined for terrestrial and marine organisms. The extant diversity of African freshwater mollusks is in general well assessed to facilitate conservation strategies and because of the medical importance of several taxa as intermediate hosts for tropical parasites. This historical accumulation of knowledge has, however, not resulted in substantial macroecological studies on the spatial distribution of freshwater mollusks. Here, we use continental distribution data and a recently developed method of random and cohesive allocation of species distribution ranges to test the relative importance of various factors in shaping species richness of Bivalvia and Gastropoda. We show that the mid-domain effect, that is, a hump-shaped richness gradient in a geographically bounded system despite the absence of environmental gradients, plays a minor role in determining species richness of freshwater mollusks in sub-Saharan Africa. The western branch of the East African Rift System was included as dispersal barrier in richness models, but these simulation results did not fit observed diversity patterns significantly better than models where this effect was not included, which suggests that the rift has played a more complex role in generating diversity patterns. Present-day precipitation and temperature explain richness patterns better than Eemian climatic condition. Therefore, the availability of water and energy for primary productivity during the past does not influence current species richness patterns much, and observed diversity patterns appear to be in equilibrium with contemporary climate. The availability of surface waters was the best predictor of bivalve and gastropod richness. Our data indicate that habitat diversity causes the observed species–area relationship, and hence, that environmental heterogeneity is a principal driver of freshwater mollusk richness on a continental scale.  相似文献   

Large slope deformations detection and monitoring along shores of the Potrerillos dam reservoir,Argentina, based on a small-baseline InSAR approach   总被引：1，自引：0，他引：1  

Clément Michoud  Valérie Baumann  Tom Rune Lauknes  Ivanna Penna  Marc-Henri Derron  Michel Jaboyedoff 《Landslides》2016,13(3):451-465

The Argentina National Road 7 that crosses the Andes Cordillera within the Mendoza province to connect Santiago de Chile and Buenos Aires is particularly affected by natural hazards requiring risk management. Integrated in a research plan that intends to produce landslide susceptibility maps, we aimed in this study to detect large slope movements by applying a satellite radar interferometric analysis using Envisat data, acquired between 2005 and 2010. We were finally able to identify two large slope deformations in sandstone and clay deposits along gentle shores of the Potrerillos dam reservoir, with cumulated displacements higher than 25 mm in 5 years and towards the reservoir. There is also a body of evidences that these large slope deformations are actually influenced by the seasonal reservoir level variations. This study shows that very detailed information, such as surface displacements and above all water level variation, can be extracted from spaceborne remote sensing techniques; nevertheless, the limitations of InSAR for the present dataset are discussed here. Such analysis can then lead to further field investigations to understand more precisely the destabilising processes acting on these slope deformations.  相似文献   

Sedimentation of long-lasting wind-affected volcanic plumes: the example of the 2011 rhyolitic Cordón Caulle eruption,Chile     

Costanza Bonadonna  Raffaello Cioni  Marco Pistolesi  Manuela Elissondo  Valerie Baumann 《Bulletin of Volcanology》2015,77(2):1-19

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Hospital Laundry Wastewater Disinfection with Catalytic Photoozonation     

Lourdes Teresinha Kist  Caroline Albrecht  Ênio Leandro Machado 《洁净——土壤、空气、水》2008,36(9):775-780

Wastewater production in a hospital laundry and the treatment of the most critical wastewater stream, are assessed. Hospital laundry wastewaters are hazardous to the environment due to their high pollutant concentrations and the chemicals added during the clothes washing process. Heterogeneous photocatalysis with UV, O₃ and TiO₂ and their possible combinations were used for disinfection purposes. A ramp‐type reactor was used for TiO₂ (P25 Degussa) fixation and for photochemical diffusion of the ozonized air. After assessing 5‐day biological oxygen demand, chemical oxygen demand, pH, turbidity, and surfactant content, and checking for the presence of thermotolerant coliforms and Escherichia coli, it was concluded that UV/O₃/TiO₂ was the best process/combination, yielding a 100% disinfection rate and a microbiological inactivation of 0.5070 min^–1 for E. coli and of 0.5505 min^–1 for thermotolerant coliforms.  相似文献   

New Observing Opportunities in the Far‐Infrared and Submillimeter Range     

Albrecht Poglitsch  Eckard Sturm  Jürgen Stutzki 《Astronomische Nachrichten》2005,326(7):575-588

F01 CONDOR – 1.4 THz Hetrodyne Receiver for APEX and for GREAT on SOFIA F02 FLASH – a First Light APEX Submillimeter Heterodyne instrument F03 GREAT – The German first light heterodyne instrument for SOFIA F04 CHAMP+ – A powerfull submillimeter array for the APEX telescope F05 The JamesWebb Space Telescope (JWST) and its Mid Infrared Instrument (MIRI) F06 CHARM – a Compact Heterodyne Array Receiver Module for KOSMA with Scalable Fully Reflective Focal Plane Array Optics F07 Science with Herschel‐PACS F08 CI/CO Mapping of IC 348 & Cepheus B using SMART on KOSMA F09 The warm and dense interstellar medium observed with Herschel F10 Intelligent Detectors – On‐Board Data Reduction for Future Missions F11 The Herschel Photodetector Array Camera & Spectrometer PACS F12 Why Astromineralogy Should Care about the Far‐infrared Range F13 ESI: A European Imaging Far‐Infrared Spectrometer for the Japanese SPICA space observatory F14 STAR – A 16 Pixel Terahertz Array Receiver for SOFIA F15 FIFI LS, a Field‐Imaging Far‐Infrared Line‐Spectrometer for SOFIA F16 Characterization of high‐ and low‐stressed Ge:Ga array cameras for Herschel's PACS instrument F17 Herschel / PACS Guaranteed Time Programs at MPIA F18 NANTEN2: CI and mid‐J CO surveys of clouds and galaxies of the southern sky  相似文献   

The Far‐Infrared Emission of Galaxies     

Carsten Kramer  Albrecht Poglitsch  Jürgen Stutzki  Andreas Eckart 《Astronomische Nachrichten》2005,326(7):523-534

C01 Study of local infrared bright galaxies with HERSHCEL‐PACS C02 PDR modeling of the COBE Far‐Infrared data of the Milky Way C03 MAMBO observations of BzK‐selected vigorous starburst galaxies at z ∼ 2 C04 Starburst galaxies in the far‐infrared. Modelling the line, PAH and dust continuum emission C05 The SED from isothermal clouds C06 PDRs in M83 and M51: The road to HIFI/Herschel and SOFIA C07 Large Scale Mapping of Molecular Gas in the Vicinity of 30 Doradus in the Large Magellanic Cloud C08 Modelling far‐infrared emission from dust in gas‐rich galaxies C09 [CII]/CO(1‐0) Line Ratio at low Metallicities C10 Gas, Stars and Dust in the Spiral Arms of M51 C11 The ISOPHOT 170 micron Serendipity Survey (ISOSS) catalog of optically identified galaxies C12 Spitzer Images of M33: A Probe to Radio‐FIR Correlation C13 Observations of far‐infrared emission from dust in gas‐rich galaxies C14 Dust and Gas in Nearby Galaxies: First Results from SINGS and THINGS C15 Sequential Starburst in Arp220?  相似文献   

Sensitivity study of pulsed neutron-gamma saturation monitoring at the Altmark site in the context of CO2 storage     

Gunther Baumann  Jan Henninges 《Environmental Earth Sciences》2012,67(2):463-471

The injection of CO₂ into depleted natural gas reservoirs has been proposed as a promising new technology for combining enhanced gas recovery and geological storage of CO₂. During the injection, application of suitable techniques for monitoring of the induced changes in the subsurface is required. Observing the movement and the changes in saturation of the fluids contained in the reservoir and the confining strata is among the primary aims here. It is shown that under conditions similar to the Altmark site, Germany, pulsed neutron-gamma logging can be applied with limitations. The pulsed neutron-gamma method can be applied for detection and quantification of changes in brine saturation and water content, whereas changes in the gas composition are below the detection limit. A method to account for the effects of salt precipitation resulting from evaporation of residual brine is presented.  相似文献   

The impact of diagenetic fluid–rock reactions on Rotliegend sandstone composition and petrophysical properties (Altmark area, central Germany)     

Dieter Pudlo  Viktor Reitenbach  Daniel Albrecht  Leonhard Ganzer  Ulrich Gernert  Joachim Wienand  Bernd Kohlhepp  Reinhard Gaupp 《Environmental Earth Sciences》2012,67(2):369-384

In the framework of the German R&D joint project CLEAN (CO₂ large-scale enhanced gas recovery in the Altmark natural gas field), Rotliegend reservoir sandstones of the Altensalzwedel block in the Altmark area (Saxony-Anhalt, central Germany) have been studied to characterise litho- and diagenetic facies, mineral content, geochemical composition, and petrophysical properties. These sands have been deposited in a playa environment dominated by aeolian dunes, dry to wet sand flats and fluvial channel fills. The sediments exhibit distinct mineralogical, geochemical, and petrophysical features related to litho- and diagenetic facies types. In sandstones of the damp to wet sandflats, their pristine red colours are preserved and porosity and permeability are only low. Rocks of the aeolian environment and most of the channel fill deposits are preferentially bleached and exhibit moderate to high porosity and permeability. Although geochemical element whole rock content in these rocks is very similar, element correlations are different. Variations in porosity and permeability are mainly due to calcite and anhydrite dissolution and differences in clay coatings with Fe-bearing illitic-chloritic composition exposed to the pore space. Moreover, mineral dissolution patterns as well as compositions (of clays and carbonate) and morphotypes of authigenic minerals (chlorite, illite) are different in red and bleached rocks. Comparison of the geochemical composition and mineralogical features of diagenetically altered sandstones and samples exposed to CO₂-bearing fluids in laboratory batch experiments exhibit similar character. Experiments prove an increase in wettability and water binding capacity during CO₂ impact.  相似文献   

The flood in the Oder River 1997 — impact on water quality     

Albrecht Müller 《Ocean Dynamics》1998,50(2-3):245-251

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