A calibration system for superconducting gravimeters     

Vladimiro Achilli  Paolo Baldi  Giuseppe Casula  Mario Errani  Sergio Focardi  Marco Guerzoni  Federico Palmonari  Giuseppe Raguní 《Journal of Geodesy》1995,69(2):73-80

A new method for the calibration of a superconducting gravity meter is described, in which a 273 Kg annular mass is placed around the meter and is moved up and down. The geometry of the apparatus is easy to model and the accuracy in the computation of the gravity variation induced by the mass, 6.7µgal, is limited only by the accuracy in the knowledge of value of the gravitational constant. Measurements done in 91 and 92 for the calibration of the instrument GWR-T015 are described. The calibration factor has been determined with a precision of about 0.3%.  相似文献   

The compton effect in the chromosphere,III     

Marco Missana 《Astrophysics and Space Science》1982,85(1-2):137-157

It is shown that in the solar spectrum at the centre of the disc there is evidence of a red shift due to generalized Compton effect and Thomson scattering in the chrosmophere. It is also shown that there is no proof of the Einstein effect.The analysis of the emission lines of the limb spectrum confirms this point of view and is in accord with the previous results obtained from the study of the ultraviolet limb spectrum.At last a study of the spectra of Orionis suggests the possibility that a quite large Compton red shift is present in the spectrum of the star.  相似文献   

Strain partitioning and stress rotation at the North Anatolian fault zone from aftershock focal mechanisms of the 1999 Izmit M_w= 7.4 earthquake     

Marco Bohnhoff  Helmut Grosser  Georg Dresen 《Geophysical Journal International》2006,166(1):373-385

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Validation through HVSR measurements of a method for the quick detection of site amplification effects from intensity data: an application to a seismic area in Northern Italy     

Vera D'Amico  Marco Mucciarelli   《Soil Dynamics and Earthquake Engineering》2002,22(6)

An instrumental validation is attempted of an innovative approach devoted to the quick individuation, from macroseismic data, of site amplification phenomena able to significantly modify seismic hazard levels expected on the basis of average propagation effects only. According to this methodology, two evaluations of hazard are performed at each investigated locality: the former, obtained by epicentral intensity data ‘reduced’ at the site through a probabilistic attenuation function and, the latter, computed by integrating such data with seismic effects actually observed at the site during past earthquakes. The comparison, for each locality, between these two hazard estimates allow to orientate the identification of those sites where local amplifications of earthquake ground motion could be significant. In order to check such methodology, indications obtained in this way from macroseismic data are compared with the estimates of transfer functions performed through the HVSR technique applied to microtremors. Results concerning municipalities located in a seismic area of Northern Italy indicate a good agreement between macroseismic and instrumental estimates.  相似文献   

The BEAM-project: prediction and assessment of mixture toxicities in the aquatic environment     

Thomas Backhaus  Rolf Altenburger  sa Arrhenius  Hans Blanck  Michael Faust  Antonio Finizio  Paola Gramatica  Matthias Grote  Marion Junghans  Wiebke Meyer  Manuela Pavan  Tobias Porsbring  Martin Scholze  Roberto Todeschini  Marco Vighi  Helge Walter  L. Horst Grimme 《Continental Shelf Research》2003,23(17-19):1757

Freshwater and marine ecosystems are exposed to various multi-component mixtures of pollutants. Nevertheless, most ecotoxicological research and chemicals regulation focus on hazard and exposure assessment of individual substances only, the problem of chemical mixtures in the environment is ignored to a large extent. In contrast, the assessment of combination effects has a long tradition in pharmacology, where mixtures of chemicals are specifically designed to develop new products, e.g. human and veterinary drugs or agricultural and non-agricultural pesticides. In this area, two concepts are frequently used and are thought to describe fundamental relationships between single substance and mixture effects: Independent Action (Response Addition) and Concentration Addition. The question, to what extent these concepts may also be applied in an ecotoxicological and regulatory context may be considered a research topic of major importance, as the concepts would allow to make use of already existing single substance toxicity data for the predictive assessment of mixture toxicities. Two critical knowledge gaps are identified: (a) There is a lack of environmental realism, as a huge part of our current knowledge about the applicability of the concepts is restricted to artificial situations with respect to mixture composition or biological effect assessment. (b) The knowledge on what exactly is needed for using the concepts as tools for the predictive mixture toxicity assessment is insufficient. Both gaps seriously hamper the necessary, scientifically sound consideration of mixture toxicities in a regulatory context.In this paper, the two concepts will be briefly introduced, the necessity of considering the toxicities of chemical mixtures in the environment will be demonstrated and the applicability of Independent Action and Concentration Addition as tools for the prediction and assessment of mixture toxicities will be discussed. An overview of the specific aims and approaches of the BEAM project to fill in the identified knowledge gaps is given and first results are outlined.  相似文献   

Magnetobiostratigraphy of the Spathian to Anisian (Lower to Middle Triassic) Kçira section, Albania     

Giovanni Muttoni  Dennis V. Kent  Selam Meço  Alda Nicora  Maurizio Gaetani  Marco Balini  Daniela Germani  Roberto Rettori 《Geophysical Journal International》1996,127(2):503-514

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Quantifying uncertainty in reservoir performance using streamtubes   总被引：1，自引：0，他引：1  

Marco R. Thiele  Srinivas E. Rao  Martin J. Blunt 《Mathematical Geology》1996,28(7):843-856

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Greenhouse Gas Emissions from Hydroelectric Reservoirs in Tropical Regions   总被引：2，自引：1，他引：2  

Luiz Pinguelli Rosa  Marco Aurelio dos Santos  Bohdan Matvienko  Ednaldo Oliveira dos Santos  Elizabeth Sikar 《Climatic change》2004,66(1-2):9-21

This paper discusses emissions by power-dams in the tropics. Greenhouse gas emissions from tropical power-dams are produced underwater through biomass decomposition by bacteria. The gases produced in these dams are mainly nitrogen, carbon dioxide and methane. A methodology was established for measuring greenhouse gases emitted by various power-dams in Brazil. Experimental measurements of gas emissions by dams were made to determine accurately their emissions of methane (CH₄) and carbon dioxide (CO₂) gases through bubbles formed on the lake bottom by decomposing organic matter, as well as rising up the lake gradient by molecular diffusion.The main source of gas in power-dams reservoirs is the bacterial decomposition (aerobic and anaerobic) of autochthonous and allochthonous organic matter that basically produces CO₂ and CH₄. The types and modes of gas production and release in the tropics are reviewed.  相似文献   

Structural controls on gold mineralisation and the nature of related fluids of the Paiol gold deposit, Almas Greenstone Belt, Brazil     

Mrcio Anselmo Duarte Ferrari  Asit Choudhuri 《Ore Geology Reviews》2004,24(3-4):173

Chemical analyses suggest that the metavolcanic rocks of the Almas Greenstone Belt (AGB), Tocantins State, Brazil have a continental affinity, possibly related to a continental rift environment. They were metamorphosed to amphibolite facies during a regional tectono-metamorphic event (D_n), retrogressed to greenschist facies assemblages and then hydrothermally altered within dextral strike–slip shear zones (D_n+1). Fracture sets related to D_n+2 intersect S_n+1.The Paiol Gold Mine is one of several mineralised zones within metabasic and meta-intermediate rocks of the AGB. It exploits shoots of sulphide–Au–quartz mineralisation that occupy dilational zones approximately perpendicular to an elongation lineation (L_n+1) within mylonitic foliation S_n+1 (S_n+1=S within the S–C fabric). The dilational zones probably formed due to dextral displacement on sinistrally en echelon C surfaces. Minor amounts of gold may have been introduced or remobilised during D_n+2.Coexisting primary and pseudosecondary fluid inclusions in mineralised quartz veins from ore shoots comprise a high-salinity three-phase type (Type II) and a lower salinity two-phase type (Type I). Homogenisation temperatures for Type II inclusions range from 200 to 410 °C and Type I from 90 to 320 °C. The inclusions and their temperature ranges are believed to reflect heat exchange and some mixing between the two fluid types under relatively constant ambient temperatures, but variable (though broadly declining) fluid temperatures. This took place late in D_n+1 in conjunction with greenschist facies retrogression and localised hydrothermally induced metasomatism.  相似文献   

L'archivage des activités humaines par les neiges et glaces polaires : le cas du plomb     

Claude Boutron  Kevin Rosman  Carlo Barbante  Michael Bolshov  Freddy Adams  Sungmin Hong  Christophe Ferrari 《Comptes Rendus Geoscience》2004,336(10):847-867

The investigation of the occurrence of lead in dated snow and ice from Greenland and Antarctica has played a major role in our understanding of the history of the pollution of the atmosphere of our planet by this metal. Such studies have however proved to be very demanding, mainly because of the extreme purity of polar snow and ice. Reliable measurements can be obtained only if ultra-clean and highly sensitive procedures are used, as pioneered by Clair Patterson. The Greenland data show evidence of large-scale pollution of the atmosphere of the Northern Hemisphere for lead as early as two millennia ago during Greco–Roman times, especially because of mining and smelting activities in southern Spain. It peaked at the end of the 1960s, with lead concentrations in snow about 200 times higher than natural values, before declining during recent times because of the fall in the use of leaded gasoline. Lead pollution in Antarctica was already significant at the end of the 19th century as a consequence of whaling activities, the traffic of coal-powered ships crossing the Cape Horn, and mining activities in South America, South Africa and Australia. After declining because of the opening of the Panama Canal, the great economic depression and World War II, it reached a maximum during the 1980s, with lead concentrations 20 times higher than natural values. Other studies focus on past natural variations of lead in ancient ice dated from the last climatic cycles. To cite this article: C. Boutron et al., C. R. Geoscience 336 (2004).  相似文献