A high-velocity ionized outflow and XUV photosphere in the narrow emission line quasar PG1211+143   总被引：1，自引：0，他引：1  

K. A. Pounds  J. N. Reeves  A. R. King  K. L. Page  P. T. O'Brien  M. J. L. Turner 《Monthly notices of the Royal Astronomical Society》2003,345(3):705-713

We report on the analysis of a ∼60-ks XMM–Newton observation of the bright, narrow emission line quasar PG1211+143. Absorption lines are seen in both European Photon Imaging Camera and Reflection Grating Spectrometer spectra corresponding to H- and He-like ions of Fe, S, Mg, Ne, O, N and C. The observed line energies indicate an ionized outflow velocity of ∼24 000 km s⁻¹. The highest energy lines require a column density of   N _H∼ 5 × 10²³ cm⁻²  , at an ionization parameter of  log ξ∼ 3.4  . If the origin of this high-velocity outflow lies in matter being driven from the inner disc, then the flow is likely to be optically thick within a radius of ∼130 Schwarzschild radii, providing a natural explanation for the big blue bump (and strong soft X-ray) emission in PG1211+143.  相似文献   

Assessment of North Sea industrial fish stocks with incomplete catch-at-age data     

Cook  R. M.; Reeves  S. A. 《ICES Journal of Marine Science》1993,50(4):425-434

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European species of Thlaspi L. (Cruciferae) as indicators of nickel and zinc     

R.D. Reeves  R.R. Brooks 《Journal of Geochemical Exploration》1983,18(3):275-283

The analysis of herbarium specimens has shown that unusual metal uptake by European species of Thlaspi (Cruciferae, mustard family) is not confined to the well-known accumulation of zinc from calaminiferous soils. At least twelve species show unusual accumulation of nickel, to levels of 1000–30,000 μg/g (dry-mass basis), from serpentine or other nickel-rich substrates. In addition, accumulation of zinc to levels above 1000 μg/g in the dry mass of the plant is widespread; about three-quarters of the European species, from a wide variety of soil types, have been found to exhibit this behaviour in the natural state. These observations are significant in many fields, including taxonomy, plant physiology and phytochemistry, but are particularly important in extending the potential of biogeochemical methods of mineral exploration.  相似文献   

Subterranean Natural Brines Produce Sodium Sulphate in West Texas     

C. C. Reeves  Jr. 《Ground water》1963,1(3):35-36

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Recharge and pollution of the english chalk: Some possible mechanisms     

M.J. Reeves 《Engineering Geology》1979,14(4):231-240

Pore water in the Chalk is likely to remain essentially static under the influence of environmental forces with the exception of evapotranspiration. A process of piston displacement of water through networks of microfissures provides a possible mechanism for downward percolation through the unsaturated Chalk.

Maintenance of continuous diffusion equilibrium between fissure and pore water throughout downward migration allows the explanation of the observed rates of movement for thermonuclear tritium in the unsaturated zone. Activation of increasingly large fissures with increasing infiltration rates explains observed rapid water-table response under conditions of sustained high inflow, and is consistent with the behaviour of water quality parameters in the saturated aquifer. Whereas in the unsaturated zone it is suggested that 80 to 90% of total flow passes through microfissures, in the saturated aquifer fluid transport is essentially through macrofissures. Diffusion equilibrium between pore water and fissure water in the saturated zone is not therefore expected.

Individual macrofissures occasionally are enlarged by solution, making it possible for a large proportion of saturated flow to take place through relatively few preferential flow channels. Although the macrofissures, and particularly enlarged macrofissures, are largely responsible for aquifer transmissivity, microfissure storage may often be highly significant in terms of specific yield.  相似文献   

Teleseismic delay times,Bouguer anomalies and inferred thickness of the African lithosphere     

J.D. Fairhead  C.V. Reeves 《Earth and Planetary Science Letters》1977,36(1):63-76

Teleseismic P-wave travel time residuals (delay times) have been determined for 38 African seismograph stations using a total of 104 presumed Russian underground nuclear explosions. The delay times (T) for seismograph stations situated on Precambrian crust within the interior of Africa, where surface erosion is minimal, appear to be linearly related to both the station elevation (E) and Bouguer anomaly (B) such that: T=(1.12±0.32)E?(1.81±0.44)(1) T=?(0.013±0.005)B?(1.81±0.60)(2) where T is in seconds,E in kilometres and B in milligals. Equation 2 has been used to predict delay times more generally using the smoothed Bouguer anomaly map of Africa. The delay time map is tentatively used to derive a map of lithosphere thickness which takes into account lateral variations of velocity within both the lithosphere and asthenosphere. The lithospheric thickness model indicates a major zone of thin lithosphere (or thick asthenosphere) is associated with the East African Rift system and its continuation into southern Africa. Concomitant seismicity and volcanism further suggest that incipient separation of the continental plate is taking place along the axis of this zone.  相似文献   

Botswana gravity reference net     

R. M. Carruthers  C. V. Reeves 《Journal of Geodesy》1974,48(4):409-418

Gravity reference stations for the National Gravity Survey of Botswana have been established at twenty-three sites throughout the country in a net linked to existing bases in South Africa, Kenya and Zambia with an internal accuracy of better than 0.5 gravity units (one gravity unit, gu, equals an acceleration of 10⁻⁶ m.s⁻²). The field procedure and reduction of data are explained and a list is given of the gravity values.  相似文献   

The fate of terrestrial organic matter in two Scottish sea lochs     

P.S. Loh  A.D. Reeves  S.M. Harvey  J. Overnell  A.E.J. Miller 《Estuarine, Coastal and Shelf Science》2008

Sea lochs are zones of rapid organic matter (OM) turnover. Most of this OM is of allochthonous origin, being introduced into the lochs via freshwater input. In this study the behaviour of terrestrially derived OM was elucidated using a combination of parameters which indicate OM diagenesis in the near surface sediments from two Scottish sea lochs, Loch Creran and Loch Etive. Alkaline CuO oxidation was used to determine lignin phenols which serve as biomarkers for terrestrial OM in sediments. Stable carbon isotope, total carbon and nitrogen and total OM (including the labile and refractory fractions) compositions were also determined.  相似文献   

Erratum: Discriminant analysis for estimation of groundwater age from hydrochemistry and well construction: application to New Zealand aquifers     

Christopher J. Daughney  Uwe Morgenstern  Rob van der Raaij  Robert R. Reeves 《Hydrogeology Journal》2010,18(2):541-541

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EMPLOYMENT DATA AND THE CLASSIFICATION OF URBAN SETTLEMENTS     

Gordon F. Mulligan  Richard W. Reeves 《The Professional geographer》1986,38(4):349-358

Classifications of urban settlements have traditionally used total employment data in place of basic (export-oriented) employment data. While urban analysis agree upon the superiority of basic employment data for these classifications, usually only total employment data are available. This paper uses the Arizona Community Data Set, a unique survey-generated body of information that describes the major economic characteristics of numerous Southwestern communities and includes both basic and total employment data, to explore the extent to which misclassification results when using total employment data.  相似文献