Direct observation of cosmic strings via their strong gravitational lensing effect – I. Predictions for high-resolution imaging surveys     

M. Alice Gasparini  Phil Marshall  Tommaso Treu  Eric Morganson  Florian Dubath 《Monthly notices of the Royal Astronomical Society》2008,385(4):1959-1964

We use present theoretical estimates for the density of long cosmic strings to predict the number of strong gravitational lensing events in astronomical imaging surveys as a function of the angular resolution and survey area. We show that angular resolution is the single most important factor, and that interesting limits on the dimensionless string tension   G μ/ c ²  can be obtained by existing and planned surveys. At the resolution of the Hubble Space Telescope ( HST ) (0.14 arcsec), it is sufficient to survey of the order of a few square degrees – well within reach of the current HST archive – to probe the regime   G μ/ c ²∼ 10⁻⁷  . If lensing by cosmic strings is not detected, such a survey would improve the limit on the string tension by a factor of two over that available from the cosmic microwave background. Future high resolution imaging surveys, covering a few hundred square degrees or more, either from space in the optical or from large-format radio telescopes on the ground, would be able to further lower this limit to   G μ/ c ²∼ 10⁻⁸  . These limits will not be improved significantly by increasing the solid angle of the survey.  相似文献   

Toroidal,Counter-Toroidal,and Upwelling Flow in the Mantle Wedge of the Rivera and Cocos Plates: Implications for IOB Geochemistry in the Trans-Mexican Volcanic Belt     

Florian Neumann  Alberto Vásquez-Serrano  Gustavo Tolson  Raquel Negrete-Aranda  Juan Contreras 《Pure and Applied Geophysics》2016,173(10-11):3395-3417

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Energy balance closure for the LITFASS-2003 experiment   总被引：2，自引：1，他引：1  

Thomas Foken  Matthias Mauder  Claudia Liebethal  Florian Wimmer  Frank Beyrich  Jens-Peter Leps  Siegfried Raasch  Henk A. R. DeBruin  Wouter M. L. Meijninger  Jens Bange 《Theoretical and Applied Climatology》2010,101(1-2):149-160

In the first part, this paper synthesises the main results from a series of previous studies on the closure of the local energy balance at low-vegetation sites during the LITFASS-2003 experiment. A residual of up to 25% of the available energy has been found which cannot be fully explained either by the measurement uncertainty of the single components of the surface energy balance or by the length of the flux-averaging period. In the second part, secondary circulations due to heterogeneities in the surface characteristics (roughness, thermal and moisture properties) are discussed as a possible cause for the observed energy balance non-closure. This hypothesis seems to be supported from the fluxes derived from area-averaging measurement techniques (scintillometers, aircraft).  相似文献   

Origin of light volatile hydrocarbon gases in mud volcano fluids, Gulf of Cadiz — Evidence for multiple sources and transport mechanisms in active sedimentary wedges     

Marianne Nuzzo  Edward R.C. Hornibrook  Fiona Gill  Christian Hensen  Richard D. Pancost  Matthias Haeckel  Anja Reitz  Florian Scholz  Vitor H. Magalhes  Warner Brückmann  Luis M. Pinheiro 《Chemical Geology》2009,266(3-4):359-372

Widespread mud volcanism across the thick (≤ 14 km) seismically active sedimentary prism of the Gulf of Cadiz is driven by tectonic activity along extensive strike–slip faults and thrusts associated with the accommodation of the Africa–Eurasia convergence and building of the Arc of Gibraltar, respectively. An investigation of eleven active sites located on the Moroccan Margin and in deeper waters across the wedge showed that light volatile hydrocarbon gases vented at the mud volcanoes (MVs) have distinct, mainly thermogenic, origins. Gases of higher and lower thermal maturities are mixed at Ginsburg and Mercator MVs on the Moroccan Margin, probably because high maturity gases that are trapped beneath evaporite deposits are transported upwards at the MVs and mixed with shallower, less mature, thermogenic gases during migration. At all other sites except for the westernmost Porto MV, δ¹³C–CH₄ and δ²H–CH₄ values of ~ − 50‰ and − 200‰, respectively, suggest a common origin for methane; however, the ratio of CH₄/(C₂H₆ + C₃H₈) varies from ~ 10 to > 7000 between sites. Mixing of shallow biogenic and deep thermogenic gases cannot account for the observed compositions which instead result mainly from extensive migration of thermogenic gases in the deeply-buried sediments, possibly associated with biodegradation of C₂₊ homologues and secondary methane production at Captain Arutyunov and Carlos Ribeiro MVs. At the deep-water Bonjardim, Olenin and Carlos Ribeiro MVs, generation of C₂₊-enriched gases is probably promoted by high heat flux anomalies which have been measured in the western area of the wedge. At Porto MV, gases are highly enriched in CH₄ having δ¹³C–CH₄ ~ − 50‰, as at most sites, but markedly lower δ²H–CH₄ values < − 250‰, suggesting that it is not generated by thermal cracking of n-alkanes but rather that it has a deep Archaeal origin. The presence of petroleum-type hydrocarbons is consistent with a thermogenic origin, and at sites where CH₄ is predominant support the suggestion that gases have experienced extensive transport during which they mobilized oil from sediments ~ 2–4 km deep. These fluids then migrate into shallower, thermally immature muds, driving their mobilization and extrusion at the seafloor. At Porto MV, the limited presence of petroleum in mud breccia sediments further supports the hypothesis of a predominantly deep microbial origin of CH₄.  相似文献   

Erratum to M. Mangalo, F. Einsiedl, R. U. Meckenstock and W. Stichler (2008) “Influence of the enzyme dissimilatory sulfite reductase on stable isotope fractionation during sulfate reduction”, Geochimica et Cosmochimica Acta 72, 1513-1520     

Florian Einsiedl 《Geochimica et cosmochimica acta》2009,73(9):2692

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Calcium Isotopes (δ^44/40Ca) in MPI-DING Reference Glasses, USGS Rock Powders and Various Rocks: Evidence for Ca Isotope Fractionation in Terrestrial Silicates     

Marghaleray Amini  Anton Eisenhauer  Florian Böhm  Chris Holmden  Katharina Kreissig  Folkmar Hauff  Klaus Peter Jochum 《Geostandards and Geoanalytical Research》2009,33(2):231-247

We report δ^44/40Ca_{(SRM 915a)} values for eight fused MPI‐DING glasses and the respective original powders, six USGS igneous rock reference materials, the U‐Th disequilibria reference material TML, IAEA‐CO1 (Carrara marble) and several igneous rocks (komatiites and carbonatites). Sample selection was guided by three considerations: (1) to address the need for information values on reference materials that are widely available in support of interlaboratory comparison studies; (2) support the development of in situ laser ablation and ion microprobe techniques, which require isotopically homogenous reference samples for ablation; and (3) provide Ca isotope values on a wider range of igneous and metamorphic rock types than is currently available in the scientific literature. Calcium isotope ratios were measured by thermal ionisation mass spectrometry in two laboratories (IFM‐GEOMAR and Saskatchewan Isotope Laboratory) using ⁴³Ca/⁴⁸Ca‐ and ⁴²Ca/⁴³Ca‐double spike techniques and reported relative to the calcium carbonate reference material NIST SRM 915a. The measurement uncertainty in both laboratories was better than 0.2‰ at the 95% confidence level. The impact of different preparation methods on the δ^44/40Ca_{(SRM 915a)} values was found to be negligible. Except for ML3‐B, the original powders and the respective MPI‐DING glasses showed identical δ^44/40Ca_{(SRM 915a)} values; therefore, possible variations in the Ca isotope compositions resulting from the fusion process are excluded. Individual analyses of different glass fragments indicated that the glasses are well homogenised on the mm scale with respect to Ca. The range of δ^44/40Ca_{(SRM 915a)} values in the igneous rocks studied was larger than previously observed, mostly owing to the inclusion of ultramafic rocks from ophiolite sections. In particular, the dunite DTS‐1 (1.49 ± 0.06‰) and the peridotite PCC‐1 (1.14 ± 0.07‰) are enriched in ⁴⁴Ca relative to volcanic rocks (0.8 ± 0.1‰). The Carrara marble (1.32 ± 0.06‰) was also found to be enriched in ⁴⁴Ca relative to the values of assumed precursor carbonates (< 0.8‰). These findings suggest that the isotopes of Ca are susceptible to fractionation at high temperatures by, as yet, unidentified igneous and metamorphic processes.  相似文献   

Influence of Mediterranean sea-level changes on the Dacic Basin (Eastern Paratethys) during the late Neogene: the Mediterranean Lago Mare facies deciphered   总被引：2，自引：0，他引：2  

Georges Clauzon  Jean-Pierre Suc†  Speranta-Maria Popescu†  Mariana Marunteanu‡  Jean-Loup Rubino¶  Florian Marinescu‡  Mihaela Carmen Melinte§ 《Basin Research》2005,17(3):437-462

A recently published scenario viewing the Messinian salinity crisis as two evaporitic steps rather than one has led to a search for new indices of the crisis in the Eastern Paratethys. Fluvial processes characterized the southwestern Dacic Basin (Southern Romania, i.e. the Carpathian foredeep) whereas brackish sediments were continuously deposited in its northern part. This is consistent with previously evidenced responses of the Black Sea to the Messinian salinity crisis. High sea‐level exchanges between the Mediterranean Sea and Eastern Paratethys are considered to have occurred just before and just after desiccation of the Mediterranean. This accounts for two successive Mediterranean nannoplankton‐dinocyst influxes into the Eastern Paratethys that, respectively, belong to zones NN 11 and NN 12. Meanwhile, two separate events that gave rise to Lago Mare facies (with Paratethyan Congeria, ostracods and/or dinoflagellate cysts) arose in the Mediterranean Basin in response to these high sea‐level exchanges and located 5.52 and 5.33 Ma (isotopic stages TG 11 and TG 5, respectively), i.e. just before and just after the almost complete desiccation of the Mediterranean). These Lago Mare facies formed independently of lakes with ostracods of the Cyprideis group that developed in the central basins during the final stages of desiccation. The gateway faciliting these water exchanges is not completely identified. A proto‐Bosphorus strait seems unlikely. A plausible alternative route extends from the northern part of the Thessaloniki region up to the Dacic Basin and through Macedonia and the Sofia Basin. The expression ‘Lago Mare’ is chronostratigraphically ambiguous and should be discontinued for this purpose, although it might remain useful as a palaeoenvironmental term.  相似文献   

Magnetic interaction analysis of basaltic samples and pre-selection for absolute palaeointensity measurements     

Florian Wehland  Roman Leonhardt  Fabienne Vadeboin  Erwin Appel 《Geophysical Journal International》2005,162(2):315-320

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Implications of EU-Water Framework Directive for the East German Postmining Landscape Lausitz: Coping with a sparse knowledge of the underground   总被引：1，自引：0，他引：1  

Bastian Johannes Graupner  Friedrich-Carl Benthaus  Stephan Bürger  Florian Werner 《Limnologica》2005,35(3):199-205

Mining dumps are major sources of pollutants within the mining area of Lausitz, especially sulphate and iron. Their existence in catchment areas comprising groundwater bodies or lakes often imposes negative effects on the water quality. The European Union Water Framework Directive [EU-WFD, 2000. Directive 2000/60/EC of the European Parliament and of the Council of 23 October 2000 establishing a framework for Community action in the field of water policy. The European Parliament and Council, L327/1, p. 72] aims to achieve ‘good quality’ status for all water bodies across Europe by 2015. Consequently, predicting the development of ground and lake water quality is necessary and must be based on the geochemical composition of the mining dumps. Therefore, the dumps need to be quantified as pollutant sources.A method to calculate the amount of sulphate in mine dumps is presented. It is based on historic geological and geochemical data characterising the pre-mining situation. Additional information on the dump body, derived from the vertical extension of mining activities and the current Digital Elevation Model (DEM), allows the composition of the dump to be determined. This procedure is demonstrated for the Bärwalde site. An average total sulphur content of 0.62% (5.9 million tonnes) was calculated for the Bärwalde dump. About 40% of it is estimated to be pyrite sulphur. Applying an average pyrite oxidation rate for the whole dump body of 7% led to an additional water-soluble mass of 0.18 million tonnes of sulphate sulphur.Applying this technique to all mine dumps managed by the postmining administration company LMBV, will improve our knowledge of the catchment area for the different lakes of Lausitz and will form an essential basis for reactive transport calculations.  相似文献   

Scheme for development of monitoring networks for springs in Bavaria, Germany     

Steffen Bender  Florian Einsiedl  Stefan Wohnlich 《Hydrogeology Journal》2001,9(2):208-216

The present groundwater monitoring network in Bavaria consists mostly of wells and only a small number of natural groundwater springs, all of which are analyzed for mainly the common physical and chemical constituents in groundwater. In order to develop a long-term groundwater management plan for all the groundwater resources of Bavaria, the Bavarian State Office for Water Management intends to establish a separate spring-monitoring network throughout the 11 groundwater provinces of the state. As a first step, significant physicochemical parameters that show considerable annual fluctuation (after monitoring 1–3 years) were determined at 21 springs or spring systems to create a basic data set to guide future monitoring. A selection procedure was developed around four parameters: (1) geological units, which includes the principal aquifers; (2) rate of spring discharge; (3) land utilization within a catchment; and (4) approximate size of the subterranean catchment. However, in the initial phase of the study, only the first three parameters were investigated. These parameters established a matrix for evaluating each groundwater region of Bavaria to aid in the selection of additional springs for the proposed monitoring network. Electronic Publication  相似文献