The influence of both process descriptions and runoff patterns on predictions from a spatially distributed soil erosion model     

Ingrid Takken  Gerard Govers  Victor Jetten  Jeroen Nachtergaele  An Steegen  Jean Poesen 《地球表面变化过程与地形》2005,30(2):213-229

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Orbital Evolution of Impact Ejecta from Ganymede     

Jose Luis AlvarellosKevin J. Zahnle  Anthony R. DobrovolskisPatrick Hamill 《Icarus》2002,160(1):108-123

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HST imaging of the globular clusters in the Fornax cluster: NGC 1379     

Rebecca A. W.Elson  Carl J.Grillmair  Duncan A.Forbes  MikeRabban  Gerard M.Williger  Jean P.Brodie 《Monthly notices of the Royal Astronomical Society》1998,295(1):240-250

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The binary star population of the young cluster NGC 1818 in the Large Magellanic Cloud     

Rebecca A. W. Elson  Steinn Sigurdsson  Melvyn Davies  Jarrod Hurley  & Gerard Gilmore 《Monthly notices of the Royal Astronomical Society》1998,300(3):857-862

We determine the binary star fraction as a function of radius in NGC 1818, a young rich cluster in the Large Magellanic Cloud, using Hubble Space Telescope images in bands F336W (∼ U ) and F555W (∼ V ). Our sample includes binaries with M _primary ∼ 2–5.5 M_⊙ and M _secondary ≳ 0.7 M_primary. The binary fraction increases towards the cluster centre, from ∼ 20 ± 5 per cent in the outer parts, to ∼ 35 ± 5 per cent inside the core. This increase is consistent with dynamical mass segregation and need not be primordial. We compare our results with expectations from N -body models, and discuss the implications for the formation and early evolution of such clusters.  相似文献   

Convective scaling of the average dissipation rate of temperature variance in the atmospheric surface layer     

Gerard Kiely  John D. Albertson  Marc B. Parlance  William E. Eichinger 《Boundary-Layer Meteorology》1996,77(3-4):267-284

The flux of sensible heat from the land surface is related to the average rate of dissipation of temperature fluctuations in the atmospheric surface layer through the temperature variance budget equation. In many cases it is desirable to estimate the heat flux from measurement or inference of the dissipation rate. Here we study how the dissipation rate scales with atmospheric stability, using three inertial range methods to calculate the dissipation rate: power spectra, second order structure functions, and third order structure functions. Experimental data are analyzed from a pair of field experiments, during which turbulent fluctuations of velocity and temperature were measured over a broad range of neutral and unstable atmospheric flows. It is shown that the temperature dissipation rate scales with a single convective power law continuously from near-neutral to strongly unstable stratification. The dissipation scaling is found to nearly match production in the near-neutral region, but to be consistently lower than production in the more convective regimes. The convective scaling is shown to offer a simplified means of computing sensible heat flux from the dissipation rate of temperature variance.Also at Johns Hopkins University, Baltimore, MarylandAlso at Los Alamos National Laboratory, Los Alamos, New Mexico.  相似文献   

Causes of low-frequency ground motion amplification in the Salt Lake Basin: the case of the vertically incident P wave     

Kim B. Olsen  Gerard T. Schuster 《Geophysical Journal International》1995,122(3):1045-1061

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Oxygen-containing functional groups in land-derived humic acids—I. Evaluation by derivatization methods     

J.M. Portal  P. Pillon  P. Jeanson  B. Gerard 《Organic Geochemistry》1986,9(6)

Determinations of reactive oxygen-containing functional groups were performed by usual chemical derivatization methods of four humic acids isolated from soils and deltaic sediments. Statistical tests and calculations based on elemental analysis demonstrated the validity and limits of these techniques and allowed us to identify from 60 to 71% of the total humic oxygen. Oxygen budgets of humic acids are discussed.  相似文献   

Oxygen-containing functional groups in land-derived humic acids—II. Changes in the oxygen distribution of humic acids during early diagenesis as revealed by derivatization methods     

P. Pillon  J.M. Portal  B. Gerard  P. Jeanson  L. Jocteur-Monrozier   《Organic Geochemistry》1986,9(6)

Extensive functional group analyses were performed on humic acids representative of eight increasing depth levels from a core drilled in the Mahakam delta (East Kalimantan, Indonesia). Oxygen amounts decrease observed during early diagenesis was related chiefly to loss of hydroxyl (lignol?) groups. Comparison between upper and deeper levels shows the following variations: hydroxyl group abundances go from 19 to 6% of humic oxygen. Identified functional groups amounts represent 47 to 32% of weight of moisture- and ash-free humic acids. No evidence of decarboxylation of humic material was detected.  相似文献   

Asbestos in lake and reservoir waters of Staten Island,New York: Source,concentration, mineralogy,and size distribution     

Gerard P. Maresca  John H. Puffer  Mark Germine 《Environmental Geology》1984,6(4):201-210

There is strong evidence indicating that the six commonly recognized varieties of asbestos are cancer-producing agents Epidemiological and experimental data indicate that, although response to inhalation exposure is most marked, exposure by ingestion probably also entails a risk of excess tumor incidence. The toxicity of mineral fibers can be related to fiber dimensions, mineralogy, chemistry, and surface-active properties. In the Silver Lake Reservoir in Staten Island, New York, where chrysotile from serpentinite bedrock exposures is a potential source of contamination, chrysotile asbestos levels of 15 to 86 million fibers per liter (MFL) were measured, with an average of 53 MFL Much lower levels (average 0 3 MFL) were observed in small lakes and ponds with clayey bottoms on the Staten Island Serpentinite.  相似文献   

Hydromagnetic stability of coronal arcade structures: The effects of photospheric line tying     

Alak Ray  Gerard Van Hoven 《Solar physics》1982,79(2):353-364

A model is given of the magnetic-field equilibrium and possible dynamic excitations of a solar coronal arcade. Such structures are well observed in the spectral range from H to X-rays and often give rise to two-ribbon flares. However, the preflare state must be stable to ideal magnetohydrodynamic disturbances, and we treat this problem with particular attention to the necessary foot-point boundary conditions. Having devised a reasonably general perturbation set, we use an energy-principle analysis to show the strong stabilizing influence of inertial field-line tying at the photosphere.Address from October 1981: Tata Institute of Fundamental Research, Homi Bhabha Road, Bombay 400005, India.  相似文献