Dynamical mass estimates of young massive clusters in NGC1140 and M83     

Sarah L. Moll  Richard de Grijs  Sabine Mengel  Linda J. Smith  Paul A. Crowther 《Astrophysics and Space Science》2009,324(2-4):177-182

We present virial mass estimates of young massive clusters (YMCs) in the starburst galaxies NGC1140 and M83, determined from high spectral resolution VLT echelle spectroscopy and high spatial resolution Hubble Space Telescope imaging. The survivability of such clusters is important in testing the scenario that YMCs are potentially proto-globular clusters. As young clusters, they lie in the domain in which dynamical masses appear to overestimate true cluster masses, most likely due to the clusters not being virialised. We find that the dynamical mass of NGC1140-1 is approximately ten times greater than its photometric mass. We propose that the most likely explanation for this disparity is the crowded environment of NGC1140-1, rather than this being solely due to a lack of virial equilibrium.  相似文献   

Multiple disadvantage of older migrants and native Dutch older adults in deprived neighbourhoods in Amsterdam,the Netherlands: a life course perspective     

Sabine van der Greft  Joos Droogleever Fortuijn 《GeoJournal》2017,82(3):415-432

It is commonly suggested that older non-Western migrants have a higher risk of experiencing multiple forms of disadvantage than native older adults. However, few researchers have studied the life situation and urban conditions of older migrants in relation to each other and in comparison to native older adults with a similar socioeconomic status. This paper investigates whether different groups of older non-Western migrants (of Surinamese, Moroccan and Turkish origin) in deprived neighbourhoods in Amsterdam experience similar or different levels of multiple disadvantage compared to socioeconomically similar native Dutch older residents living in the same neighbourhoods, and explores how multiple disadvantage can be explained in relation to life and residential histories and neighbourhood changes. Analysis of 85 in-depth interviews indicates that all categories of low-income older adults experienced certain levels of disadvantage, although they evaluated their circumstances using different frames of reference. Regarding health, both native-born and migrant older people experienced chronic illness. However, the results of this study suggest that those in the latter group (especially Moroccans and Turks) experienced health problems and related functional limitations at a younger age. Native Dutch older adults were somewhat better off with respect to the availability of household resources, but compared to older non-Western migrants were more likely to experience the negative effects of neighbourhood deprivation. In summary, this study refines common assertions that older migrants are more disadvantaged than native older adults. Differences in experiences of advantage and disadvantage have their origin in differences in life and residential histories and neighbourhood change.  相似文献   

Evaluating the sulfur isotopic composition of biodegraded petroleum: The case of the Western Canada Sedimentary Basin     

Sabine Méhay  Pierre Adam  Isabelle Kowalewski  Pierre Albrecht 《Organic Geochemistry》2009,40(4):531-545

The sulfur isotopic composition (δ³⁴S) of petroleum is believed to be affected mainly by sulfur incorporation reactions into the sedimentary organic matter during the early diagenesis. However, secondary processes could affect the original δ³⁴S of oil under the effect of thermal maturity or of the microbial activity of biodegraded reservoirs. In this study, the different processes that may affect the δ³⁴S of in-reservoir oils were assessed based on the sulfur content and isotopes of a series of oil and core samples coming from various reservoirs of the Lower Cretaceous Mannville Group, Western Canada Sedimentary Basin (WCSB). Based on the molecular study, these samples appear to have reached various levels of maturity and biodegradation, ranging from 0 to 6.5 on the biodegradation scale of Peters and Moldowan. In addition, mixing of organic matter coming from different source rocks was identified based on the comparison with extensive correlation studies performed in the WCSB.Investigation of the δ³⁴S shows a trend that seems a priori correlated to the level of biodegradation. However, a careful interpretation of molecular and sulfur isotope data leads to the conclusion that the observed δ³⁴S variations have rather to be ascribed to contributions of oils generated by various source rocks. Alternatively, variations of δ³⁴S could neither be related to maturity differences nor to kinetic effects during organic sulfur compounds biodegradation. In the case of some specific core samples showing a common origin based on biomarker study, δ³⁴S variations might not be related to different sources but to secondary sulfur incorporation/exchange processes occurring within the reservoir. These processes would involve reduced sulfur species from bacterial sulfate reduction formed in situ or migrated into Mannville reservoirs. This hypothesis is supported by laboratory experiments showing sulfur exchange/incorporation under plausible conditions for shallow reservoirs.  相似文献   

Reply to comments on “Intrusive rocks and tectono-metamorphic evolution of the Mako Paleoproterozoic belt (Eastern Senegal, West Africa)”     

Mamadou Gueye  Papa Malick Ngom  Mouhamadane Dine  Yaouba Thiam  Siegfried Siegesmund  Klaus Wemmer  Sabine Pawlig 《Journal of African Earth Sciences》2009,55(5):269-270

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A thermodynamic investigation of barium and calcium sulfate stability in sediments at an oceanic ridge axis (Juan de Fuca, ODP legs 139 and 169)     

Christophe Monnin  Sabine Balleur  Bruno Goffe 《Geochimica et cosmochimica acta》2003,67(16):2965-2976

We have used a new thermodynamic model of barium and calcium sulfate solubilities in multicomponent electrolyte solutions (Monnin, 1999) to investigate the stabilities of barite and anhydrite in seawater or in marine sediment porewaters at high temperature and pressure. As a further test supplementing those previously carried out during model development, we have calculated the temperature at which standard seawater becomes saturated with respect to anhydrite. The model predicts that, upon heating at 500 bars, standard seawater becomes saturated with respect to anhydrite at 147 ± 5°C, which compares well with the literature value of 150°C (Bishoff and Seyfried, 1978). At 20 bars the calculated saturation temperature is 117 ± 3°C. This points to a non negligible pressure effect even at moderate pressures.We have calculated the barite and anhydrite saturation indices for the in situ temperatures and pressures, from the composition of porewaters collected at ODP Sites 855, 856, 857, 858, 1035 and 1036 during ODP Legs 139 and 169 (Juan de Fuca and Gorda ridges, NE Pacific). Calculated saturation indices for porewater samples collected at depths corresponding to temperatures between 70° and 110-120°C at an in situ pressure of about 260 bars yield equilibrium values for anhydrite and barite. Saturation indices of samples collected at depths where the temperature exceeds 110-120°C, however, yield values indicating supersaturation with respect to anhydrite and undersaturation with respect to barite. This result is consistent with the redissolution of anhydrite during cooling, leading to the well documented sampling artifact affecting porewater compositions in high temperature marine sediments: anhydrite dissolution increases the porewater sulfate content, which in turn induces a loss of barium from solution through barite precipitation (the common ion effect). We postulate that this redissolution occurs in sediment samples for which the in situ temperature exceeds 110-120°C: below this limit anhydrite remains at equilibrium or does not have time to significantly dissolve before porewaters are sampled.  相似文献   

Determination of the bulk temperature from NOAA/AVHRR satellite data in a midlatitude lake     

Sabine Thiemann  Helmut Schiller   《International Journal of Applied Earth Observation and Geoinformation》2003,4(4):339-349

The spatial and temporal variability of the bulk temperature gives important insights into biological and hydrodynamic processes. However, standard algorithms for satellite data only provide information of the surface temperature. The comparison of current and new split-window coefficients applied on NOAA-14/AVHRR brightness temperatures of Lake Constance showed that a regional adaption was most promising. To derive the bulk temperature information, a priori progression from a weather station was included into the AVHRR analysis. Among the weather is data, the mean temperature of the three preceding days and the day of the year were the most relevant additional information. By a multiple regression approach the bulk temperature in the upper 4 m of Lake Constance could be determined with an accuracy of ±1.20 °C. The training of a neural network improved the determination of the bulk temperature to ±1.04 °C.An extended field campaign demonstrated that the algorithm is also applicable to other sensors with the same spectral band settings (in this case NOAA-16/AVHRR) with an acceptable error and that it is equally accurate over the entire lake.  相似文献   

3D Geographic Reconstruction and Visualization Techniques Applied to Land Resource Management   总被引：1，自引：0，他引：1  

Sabine Grunwald  & Phillip Barak 《Transactions in GIS》2003,7(2):231-241

Optimized land resource management depends on reliable and detailed information describing the spatial distribution of soils, geology, topography, and land use. Soil–landscapes are three–dimensional (3D) systems commonly represented using 2D maps utilizing geographic information systems. Addressing 3D soil–landscape reality is crucial for land resource management in terms of crop growth and transport processes (e.g. nitrate leaching) that are driving soil and water quality. Our objective was to investigate the usefulness of 3D geographic information technology (GIT) applied to land resource management. Our approach is based on 2D and 3D ordinary kriging interpolating surface and subsurface attributes to reconstruct soil–landscapes. We used Virtual Reality Modeling Language, which is a web–based 3D graphics language, to visualize objects (e.g. voxels, polyhedrons) representing soil and landscape attributes. We produced a 3D block model showing the spatial distribution of bulk densities and relief for a site in southern Wisconsin and a 3D stratigraphic model showing the spatial distribution of soil horizons and relief for a site in northern Florida. Emerging GIT was used to develop 3D soil–landscape models describing continuous changes of soil and landscape attributes. Combining multimedia elements (e.g. WWW, 3D visualization, and interactivity) can produce insight that would not arise from use of the elements alone. Three–dimensional scientific visualization is a powerful tool to help us see what is invisible from above the ground.  相似文献   

Cooperite and braggite from the Bushveld Complex: implications for the miscibility gap and identification     

Merkle  Roland K. W.  Verryn  Sabine M. C. 《Mineralium Deposita》2003,38(3):381-388

Analyses of the Pt-Pd-Ni sulphides cooperite, braggite, and vysotskite reported from worldwide occurrences seem to imply a continuum of compositions between vysotskite and cooperite, with no obvious miscibility gap. This is contrary to the experimentally confirmed miscibility gap between cooperite and braggite, and the established compositional gap between co-existing cooperite and braggite from the Merensky Reef. Although the only unambiguous way of distinguishing between cooperite and braggite is to obtain structural information through X-ray diffraction or equivalent techniques, most identification of Pt-Pd-Ni sulphides is based on microanalytical techniques due to the small grain size of most platinum-group minerals. Ni contents also have to be considered because a classification based on the Pt/Pd ratio alone can be very misleading. Naming of Pt-Pd-Ni sulphide compositions with high Pt contents based on qualitative or semi-quantitative analyses should be avoided. Natural Pt-Pd-Ni sulphides which project into the compositional gap (established by experimental work) cannot be named without supporting structural information. Compositions of grains, which plot inside the gap, are considered to be metastable and to result from the loss of Pd through interaction with hydrothermal fluids.  相似文献   

Genetic sequence stratigraphy of cool water slope carbonates (Pleistocene Eucla Shelf, southern Australia)     

Sabine Saxena  Christian Betzler 《International Journal of Earth Sciences》2003,92(4):482-493

The south Australian Eucla Shelf belongs to the world's largest cool-water carbonate sedimentary system. During the Pleistocene, it exported large amounts of sediment to the shelf edge and upper slope resulting in an expanded sedimentary wedge. Wedge-internal clinoforming seismic reflectors suggest a stacking of the deposits into genetic sequences. High-resolution stable oxygen and carbon isotope, point counting, grain size, and carbonate mineralogical XRD analyses were carried out to characterize these genetic sequences along a dip-parallel transect of three ODP Leg 182 drill holes located between the shelf edge and upper slope. Oxygen and carbon isotope fluctuations show that the genetic sequences formed as a response to sea level fluctuations. Within the genetic sequences, facies differentiation and sediment volume partitioning occur along the transect. Lowstand deposits are fine grained and contain more sponge spicules and micrite. Highstand deposits are coarse grained with tunicate spicules, brown bioclasts, as well as bryozoan and corallinacean debris. Boundaries separating highstand and lowstand deposits are triggered by sea level fall, and are expressed as abrupt grain size changes or as turning points in grain-size trends. Analyzed components vary in abundance along the transect. Genetic sequences show dip-parallel variations in thickness combined with changing relative proportions of lowstand versus highstand deposits.  相似文献   

Volcanisme de l'ı̂le aux Pingouins,archipel Crozet,témoin de l'hétérogénéité du manteau fertile au sud de l'océan IndienPenguins Island,Crozet archipelago,volcanic evidence for a heterogeneous mantle in the southern Indian Ocean     

André Giret  Sylvie Tourpin  Sabine Marc  Olivier Verdier  Jean-Yves Cottin 《Comptes Rendus Geoscience》2002,334(7):481-488

Despite its small area (5.6 km²), the Penguins Island brings magmatic information concerning mantle geochemical heterogeneities in southwestern Indian Ocean. The volcanism that built the island was firstly associated with marine deposits, and secondly with aerial, giving then abundant volcanic breccias and lava flows. The rocks are weakly differentiated and result of magmatic fractionation from picritic to tephritic types. KAr ages are near 1.1 Ma. The magmatic source may be related to a HIMU reservoir or to EMI ± EMII ones, depending on the geochemical evidences that are taken into account. However, comparisons with the Marion Island, on the same oceanic plateau and far to the west, as well as with Kerguelen Islands, far to the east, suggest a very heterogeneous mantle source. To cite this article: A. Giret et al., C. R. Geoscience 334 (2002) 481–488.  相似文献