Comparison of changes in the annual variability of the seasonal cycles of chlorophyll,nutrients and zooplankton at eight locations on the northwest european continental shelf (1960–1994)     

P. V. M. Bot  W. van Raaphorst  S. Batten  R. W. P. M. Laane  K. Philippart  G. Radach  A. Frohse  H. Schultz  D. van den Eynde  F. Colijn 《Ocean Dynamics》1996,48(3-4):349-364

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Fortschritte der Fischereiwissenschaft 3 (1984), 167 S. Hrsg.: Institut für Binnenfischerei,Berlin-Friedrichshagen - DDR     

H. Schultz 《洁净——土壤、空气、水》1987,15(1):105-106

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Constraints on hydraulic parameters and implications for groundwater flux across the upland–estuary interface     

G. Schultz  C. Ruppel 《Journal of Hydrology》2002,260(1-4):255-269

Analyses of independent laboratory- and field-scale measurements from two sites on Sapelo Island, Georgia reveal heterogeneity in hydraulic parameters across the upland–estuary interface. Regardless of the method used (short-duration pumping tests, amplitude attenuation of tidal pumping data, sediment grain size distributions, and falling head permeameter tests), we obtain hydraulic conductivity of 10⁻⁴ m s⁻¹ for the fine-grained, well-sorted, clean sands that make up the upland areas. Proximal to the upland–estuary boundary, the tidal pumping analyses and permeameter tests suggest that hydraulic conductivities decrease by more than two orders of magnitude, a result consistent with the presence of a clogging layer. Such a clogging layer may arise due to a variety of physical, chemical, or biological processes. The extent and orientation of the layers of reduced hydraulic conductivity near the upland–estuary boundary influence the nature of the aquifer's response to tidal forcing. Where the lower conductivity layer forms a relatively flat creek bank, tidal pumping produces a primarily mechanical response in the adjacent aquifer. Where the creek bank is nearly vertical, there is a more direct hydraulic connection between the tidal creek and the adjacent aquifer. The clogging layer likely contributes to the development of complicated flow pathways across the upland–estuary boundary. Effective flow paths calculated from tidal pumping data terminate within the marsh, beyond the boundary of the upland aquifer, suggesting a diffuse regime of groundwater discharge in the marsh. We postulate that, in many settings, submarsh flow may be as important as seepage faces for groundwater discharge into the marsh–estuary complex.  相似文献   

The 3D electromagnetic response of the Earth to ring current and auroral oval excitation   总被引：4，自引：0，他引：4  

Ikuko Fujii  Adam Schultz 《Geophysical Journal International》2002,151(3):689-709

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Gaseous electron multiplier gain characteristics using low-pressure Ar/CO<Subscript>2</Subscript>     

T. Rogers  R. McEntaffer  T. Schultz  J. McCoy  D. Miles  J. Tutt 《Experimental Astronomy》2017,43(2):201-210

Gaseous Electron Multiplier detectors, or GEMs, show promise for use on space-based X-ray missions. Operating pressure strongly affects the gain of the detector and must be optimized for best performance. We have measured the gain characteristics of a GEM detector at various pressures below atmosphere using a mixture of Ar:CO₂ with the goal of maximizing gain to push GEM capabilities to the lowest energies possible. This paper discusses our tests, results, and their implications for choosing a detector pressure. We found that at any operating pressure the detector voltage can be adjusted to achieve roughly the same maximum gain prior to the onset of electrical discharges. We also find that the gain varies substantially by spatial location across the detector, but this variation is insensitive to changes in pressure allowing it to be calibrated and corrected if necessary. The detector pressure can therefore be optimized in the interest of other performance parameters such as leak rate, window stress, power requirements, or quantum efficiency without concern for negatively affecting the gain. These results can inform the choice of operating pressure and voltage for GEMs used onboard future space missions.  相似文献   

The stratorotational instability of Taylor-Couette flows with moderate Reynolds numbers     

G. Rüdiger  T. Seelig  M. Schultz  M. Gellert  Ch. Egbers 《地球物理与天体物理流体动力学》2017,111(6):429-447

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Heavy metal toxicity of kidney and bone tissues in South Australian adult bottlenose dolphins (Tursiops aduncus)     

Trish J. Lavery  Catherine M. Kemper  Ken Sanderson  Christopher G. Schultz  Peter Coyle  James G. Mitchell  Laurent Seuront 《Marine environmental research》2009,67(1):1-7

Metallothioneins (MT) concentration, renal damage, and bone malformations were investigated in 38 adult Tursiops aduncus carcasses to determine any associations with cadmium, copper, zinc, mercury, lead and selenium. Significantly higher concentrations of cadmium, copper, and zinc in the liver were observed in dolphins showing evidence of more advanced renal damage. No significant differences in metal or selenium concentrations in the liver were observed between groups differing in level of bone malformations. Some dolphins displayed evidence of toxicity and knowledge of metal toxicity pathways were used to elucidate the cause of these abnormalities. Two dolphins had high metal burdens, high MT concentrations, renal damage, and evidence of bone malformations, indicating possible severe and prolonged metal toxicity. One dolphin showed evidence of renal damage, but the lack of any other symptoms suggests that this was unlikely to be caused by metal toxicity. We recommend examining a range of metal toxicity symptoms simultaneously to aid in distinguishing metal toxicity from unrelated aetiologies.  相似文献   

Floor-fractured lunar craters   总被引：1，自引：0，他引：1  

Peter H. Schultz 《Earth, Moon, and Planets》1976,15(3-4):241-273

Numerous lunar craters (206 examples, mean diameter = 40km) contain pronounced floor rilles (fractures) and evidence for volcanic processes. Seven morphologic classes have been defined according to floor depth and the appearance of the floor, wall, and rim zones. Such craters containing central peaks exhibit peak heights (approximately 1km) comparable to those within well-preserved impact craters but exhibit smaller rim-peak elevation differences (generally 0–1.5km) than those (2.4km) within impact craters. In addition, the morphology, spatial distribution, and floor elevation data reveal a probable genetic association with the maria and suggest that a large number of floor-fractured craters represent pre-mare impact craters whose floors have been lifted tectonically and modified volcanically during the epochs of mare flooding. Floor uplift is envisioned as floating on an intruded sill, and estimates of the buoyed floor thickness are consistent with the inferred depth of brecciation beneath impact craters, a zone interpreted as a trap for the intruding magma. The derived model of crater modification accounts for (1) the large differences in affected crater size and age; (2) the small peak-rim elevation differences; (3) remnant central peaks within mare-flooded craters and ringed plains; (4) ridged and flat-topped rim profiles of heavily modified craters and ringed plains; and (5) the absence of positive gravity anomalies in most floor-fractured craters and some large mare-filled craters. One of the seven morphologic classes, however, displays a significantly smaller mean size, larger distances from the maria, and distinctive morphology relative to the other six classes. The distinctive morphology is attributed, in part, to the relatively small size of the affected crater, but certain members of this class represent a style of volcanism unrelated to the maria - perhaps triggered by the last major basin-forming impacts.  相似文献   

Katharina Lodders and Bruce Fegley, Jr.: The Planetary Scientist's Companion     

Ludolf Schultz 《Journal of Atmospheric Chemistry》2000,37(2):211-212

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Geoelectromagnetic induction in a heterogeneous sphere:a new three-dimensional forward solver using a conservative staggered-grid finite difference method   总被引：2，自引：0，他引：2  

M. Uyeshima  & A. Schultz 《Geophysical Journal International》2000,140(3):636-650

A conservative staggered-grid finite difference method is presented for computing the electromagnetic induction response of an arbitrary heterogeneous conducting sphere by external current excitation. This method is appropriate as the forward solution for the problem of determining the electrical conductivity of the Earth's deep interior. This solution in spherical geometry is derived from that originally presented by Mackie et al. (1994 ) for Cartesian geometry. The difference equations that we solve are second order in the magnetic field H , and are derived from the integral form of Maxwell's equations on a staggered grid in spherical coordinates. The resulting matrix system of equations is sparse, symmetric, real everywhere except along the diagonal and ill-conditioned. The system is solved using the minimum residual conjugate gradient method with preconditioning by incomplete Cholesky decomposition of the diagonal sub-blocks of the coefficient matrix. In order to ensure there is zero H divergence in the solution, corrections are made to the H field every few iterations. In order to validate the code, we compare our results against an integral equation solution for an azimuthally symmetric, buried thin spherical shell model ( Kuvshinov & Pankratov 1994 ), and against a quasi-analytic solution for an azimuthally asymmetric configuration of eccentrically nested spheres ( Martinec 1998 ).  相似文献