<正>Dear JEEEV Contributors, Readers and Friends,This first issue of the Journal of Earthquake Engineering and Engineering Vibration was born in June 2002 at the 相似文献
A three-dimensional numerical model with a prognostic salinity field is used to investigate the effect of a partial slip bottom boundary condition on lateral flow and sediment distribution in a transect of a tidally dominated channel. The transect has a symmetrical Gaussian cross-channel bottom profile. For a deep, well-mixed, tidally dominated channel, partial slip decreases the relative importance of Coriolis deflection on the generation of cross-channel flow patterns. This has profound implications for the lateral distribution of residual salinity that drives the cross-channel residual circulation pattern. Transverse sediment transport, however, is always found to be governed by a balance between advection of residual sediment concentration by residual lateral flow on the one hand and cross-channel diffusion on the other hand. Hence, the changes in the cross-channel distribution of residual salinity modify the lateral sediment distribution. For no slip, a single turbidity maximum occurs. In contrast, partial slip gives a gradual transition to a symmetrical density distribution with a turbidity maximum near each bank. For a more shallow, partially mixed tidal channel that represents the James River, a single turbidity maximum at the left bank is found irrespective of the near-bed slip condition. In this case, semi-diurnal contributions to sediment distribution and lateral flow play an important role in cross-channel sediment transport. As vertical viscosity and diffusivity are increased, a second maximum at the right bank again exists for partial slip. 相似文献
The estimation of geographical attributes is a crucial matter for many real-world problems,and the issue of accuracy stands out when the estimation is used for between-regions comparison.In this work,our concern is area attribute estimation in a GIS environment.We estimate the area attribute value with a mean Kriging technique,and the probability distribution of the estimate is derived.This is the best linear unbiased observed spatial population mean estimate and can be used in more relaxed situations than ... 相似文献
The solubility and solution mechanisms of reduced COH volatiles in Na2OSiO2 melts in equilibrium with a (H2 + CH4) fluid at the hydrogen fugacity defined by the iron-wüstite + H2O buffer [fH2(IW)] have been determined as a function of pressure (1-2.5 GPa) and silicate melt polymerization (NBO/Si: nonbridging oxygen per silicon) at 1400 °C. The solubility, calculated as CH4, increases from ∼0.2 wt% to ∼0.5 wt% in the melt NBO/Si-range ∼0.4 to ∼1.0. The solubility is not significantly pressure-dependent, probably because fH2(IW) in the 1-2.5 GPa range does not vary greatly with pressure. Carbon isotope fractionation between methane-saturated melts and (H2 + CH4) fluid varied by ∼14‰ in the NBO/Si-range of these melts.The (C..H) and (O..H) speciation in the quenched melts was determined with Raman and 1H MAS NMR spectroscopy. The dominant (C..H)-bearing complexes are molecular methane, CH4, and a complex or functional group that includes entities with CCH bonding. Minor abundance of complexes that include SiOCH3 bonding is tentatively identified in some melts. There is no spectroscopic evidence for SiC or SiCH3. Raman spectra indicate silicate melt depolymerization (increasing NBO/Si). The [CH4/CCH]melt abundance ratio is positively correlated with NBO/Si, which is interpreted to suggest that the (CCH)-containing structural entity is bonded to the silicate melt network structure via its nonbridging oxygen. The ∼14‰ carbon isotope fractionation change between fluid and melt is because of the speciation changes of carbon in the melt. 相似文献
The behaviour under seismic loading of inclined piles embedded in two idealized soil profiles, a homogeneous and a non-homogenous
“Gibson” soil, is analysed with 3D finite elements. Two structures, modeled as single-degree-of-freedom oscillators, are studied:
(1) a tall slender superstructure (Hst = 12 m) whose crucial loading is the overturning moment, and (2) a short structure (Hst = 1 m) whose crucial loading is the shear force. Three simple two-pile group are studied: (a) one comprising a vertical pile
and a pile inclined at 25°, (b) one consisting of two piles symmetrically inclined at 25°, and (c) a group of two vertical
piles. The influence of key parameters is analysed and non-dimensional diagrams are presented to illustrate the role of raked
piles on pile and structure response. It is shown that this role can be beneficial or detrimental depending on a number of
factors, including the slenderness of the superstructure and the type of pile-to-cap connection. 相似文献
High-precision in-situ ion microprobe (SIMS) oxygen isotope analysis of zircons from two diorite intrusions associated with the late Caledonian Lochnagar pluton in Scotland has revealed large differences in the degree of heterogeneity in zircon δ18O between the diorites. Zircon crystals from the Cul nan Gad diorite (CnG) show a unimodal distribution of oxygen isotope values (δ18O = 6.0 ± 0.6‰ (2σ)) and no or only minor grain-scale variation. Those from the Allt Darrarie diorite (AD1) show a large range in δ18O and an apparent bimodal distribution with modes of 6.6 ± 0.4‰ and 7.3 ± 0.4‰. Variations of up to 1.2‰ occur between and within grains; both an increase and decrease in δ18O with zircon growth has been observed. The δ18O composition of growing zircon can only change if open-system processes affect the magma composition, i.e. if material of contrasting δ18O composition is added to the magma. The variability in AD1 is interpreted to represent a cryptic record of magma mixing. A ‘deep crustal hot zone’ is a likely site for generation of the dioritic magmas which developed by mixing of residual melts and crustal partial melts or by melting of mafic lower crustal rocks. The overall small number of zircons with mantle-like δ18O values (5.3 ± 0.6‰ (2σ)) in the Lochnagar diorites is largely the product of crustal differentiation rather than crustal growth.
The δ18O of quartz from the CnG and AD1 diorites shows only minor variation (CnG: 10.9 ± 0.5‰ (2σ), AD1: 11.7 ± 0.6‰ (2σ)) within single populations, with no evidence of mixing. Quartz–zircon isotopic disequilibrium is consistent with later crystallisation of quartz from late magmatic fluids, and in case of the AD1 diorite after the inferred magma mixing from a homogenised, higher δ18O melt.
High-precision SIMS oxygen isotope analysis of zircon provides a new approach to identifying and resolving previously undetected early-stage magma mixing and constraining the compositions and origins of the component magmas. A combination of zircon, quartz and whole-rock data has proven to be a powerful tool in reconstructing the petrogenetic evolution of diorite from early crystallisation to late alteration. 相似文献
Along the deformation front of the North Ecuador–South Colombia (NESC) margin, both surface heat flow and trench sediment thickness show prominent along-strike variations, indicating significant spatial variations in sedimentation rate. Investigating these variations helps us address the important question of how trench sedimentation influences the temperature distribution along the interplate contact and the extent of the megathrust seismogenic zone. We examine this issue by analysing 1/ a new dense reflection data set, 2/ pre-stack depth migration of selected multichannel seismic reflection lines, 3/ numerous newly-identified bottom-simulating reflectors and 4/ the first heat probe measurements in the region. We develop thermal models that include sediment deposition and compaction on the cooling oceanic plate as well as viscous corner flow in the mantle wedge. We estimate that the temperature from 60–150 °C to 350–450 °C, commonly associated with the updip and downdip limits of the seismogenic zone, extends along the plate interface over a downdip distance of 160 to 190 ± 20 km. We conclude that the updip limit of the seismogenic zone for the great megathrust earthquake of 1979 is associated with low-temperature (60–70 °C) processes. Our models also suggest that 60–70% of the two-fold decrease in measured heat flow from 3°N to 2.8°N is related to an abrupt southward increase in sedimentation rate in the trench. Such a change may potentially induce a landward shift of the 60–150 °C isotherms, and thus the updip limit of the seismogenic zone, by 10 to 20 km. 相似文献
Progression from eosinophilic foci to persistent basophilic foci and carcinomas was observed in pollution-induced hepatocellular carcinogenesis in European flounder (Platichthys flesus L.) in a similar sequence as in chemically induced liver cancer in mammals. Image analysis was used to quantify enzyme activity and protein expression as visualised by enzyme and immunohistochemistry in various stages of toxipathic lesions and carcinogenesis. In eosinophilic foci, growth advantage was achieved by increased production of NADPH and pentoses for biosynthesis and cell proliferation due to increased G6PDH capacity during the first steps of clonal adaptation. Simultaneously, oxyradical production by CYP450, phase I was reduced. Overexpression of P-gp mediating multi-xenobiotic resistance was noted in basophilic cell types which persisted during progression towards carcinomas. This was accompanied by increased protein levels of oxyradical scavenging GST-A. These changes are consistent with adaptation and phenotypic expression of the multidrug or xenobiotic resistance (MDR/MXR) type in hepatocarcinomas of European flounder. 相似文献
A partial length cDNA coding for the putative PAH-inducible phenol-conjugating UDP-glucururonosyltransferases (UGT) isoform of plaice was used to isolate overlapping clones from a plaice genomic library. Sequence analysis revealed the presence of a complete gene spanning 4.1 kb for a plaice UGT which showed a strong conservation in exon structure, amino acid character and amino acid sequence with mammalian UGT1 family genes, although additional alternative upstream exon 1s were not identified in the present study. Southern blot analysis revealed a low copy number for the gene and some degree of structural polymorphism in gene structure between individuals. This was also reflected in the finding that there were significant variations between the nucleotide sequences of the plaice gene and the cDNA previously isolated from a different individual fish. Future studies will investigate the possibility that there may be phenotypic variations which could lead to alterations in susceptibility to pollutant toxicity. 相似文献
A cDNA clone for glutathione S-transferaseA (GSTA) from plaice (Pleuronectes platessa) was expressed in Eschericia coli (E. coli) and purified to homogeneity by S-hexylglutathione affinity chromatography. When compared to literature values for a variety of purified mammalian GSTs, the heterologously expressed purified plaice enzyme had moderate activity towards the model substrate 1,2-chloro-2,4-dinitrobenzene (CDNB) and exhibited a Km of 2.5 ± 2 mM and Vmax of 30.9 ± 2.3 μmol min−1 mg−1. It had little or no activity towards several other model GST substrates including 1,2-dinitrochloro-4-benzene (DCNB), ethacrynic acid (EA), and p-nitrobenzylchloride (NBC). However plaice GSTA was a relatively efficient catalyst for the conjugation of a series of alk-2-enals and alk-2,4-dienals and also 4-hydroxynonenal. The highest activity observed with this series of substrates was with trans-non-2-enal with a Km of 17.9 ± 2.2 μM and a Vmax of 3.01 ± 0.57 μmol min−1 mg−1. These unsaturated alkenals have been identified in cells and cell extracts as highly toxic products arising from peroxidation of unsaturated fatty acids particularly during periods of oxidative stress. Fish are relatively rich in polyunsaturated fatty acids and thus GSTA mediated conjugation may be an important mechanism for detoxifying peroxidised lipid breakdown products. 相似文献