Diurnal variation of urban structure in terms of time distance: A spatio-temporal analysis of an urban area

The purpose of this paper is to clarify the diurnal variations in structure of an urban area from the viewpoint of time distance. To accomplish this, for one entire day, and for the morning, noon, and evening periods, time maps are delineated by using MDS; also, the indices of accessibility and circuity are computed from the time distances. As a result, the difference in shape between the time and actual maps becomes clear especially in the morning and also in the evening. Both the accessibility and circuity measured from the time distance show a concentrically shaped pattern where the regional disparity is especially distinct within the morning and evening periods. The diurnal variations as described above are thought to occur against the backdrop of the topological traffic conditions within the study area. This revised version was published online in July 2006 with corrections to the Cover Date.     

Diffusivity anisotropy in a rhyolite and its relation to pore structure

The diffusivity anisotropy of ions through rock pore water was evaluated quantitatively by through-diffusion experiments on a rhyolite rock having anisotropic pore structure. The rhyolite has planar flow structure with elongated pore shapes to the flow direction (X–Y plane). Diffusion coefficients of K⁺ ions for the direction perpendicular to this flow structure (Z-direction) were about 5–9 times smaller than those for the orthogonal parallel directions (X- and Y-direction). Pore geometrical analyses on backscattered electron microscopic images indicated that the pore length ratios among the X-, Y-, and Z-direction were roughly 2 : 2 : 1. This shorter pore length for the Z-direction appears to reduce pore connectivity, causing larger tortuosity and smaller diffusivity for this direction. This diffusivity anisotropy needs to be taken into account for precise modeling of diffusion-limited geological processes such as contaminant transport and rock deformation.     

Variability in the Relative Penetration of Ultraviolet Radiation to Photosynthetically Available Radiation in Temperate Coastal Waters, Japan

UVR and PAR wavelengths are attenuated to different extents within the water column, causing variations in spectral composition with depth. The present investigation (a) describes the variability of UVR and PAR penetration at a station in the temperate coastal waters of Sagami Bay and determines (b) the characteristics of relative UVR penetration to the euphotic zone. Examination of the seasonal irradiance profile measurements indicated eight measurements displaying two distinct attenuation coefficients (K _d) for specific UVR wavelengths and PAR. The two attenuation coefficients observed from specific wavelengths in the water column may be caused not only by chlorophyll pigments, but also by dissolved organic material in the upper layer. The 1% depth of surface UVR at 305, 320, 340, and 380 nm averaged 10.8 ± 5.7, 14.9 ± 9.5, 19.8 ± 12.1, and 30.4 ± 17.6 m, respectively. The depth of euphotic layer displayed less variability averaging 62 ± 15 m throughout the entire study. Relative UVR penetration within the euphotic zone averaged 17.8 ± 8.1, 22.9 ± 10, 30.5 ± 13.8, and 46 ± 46.9% for 305, 320, 340, and 380 nm, respectively. A large variation of the relative transmission of UVR within the euphotic zone was found although the spectral composition was relatively stable in the air throughout the study.     

Two Se-bearing Ag–Bi Sulphosalts, Benjaminite and Matildite from the Ikuno Deposits, Hyogo Prefecture, Japan –Au–Ag Mineralization in Polymetallic Zone

Abstract: Se-bearing benjaminite and matildite are described from the polymetallic zone of the Ikuno deposits, Japan. The former is the first occurrence in Japan, and is from two separate veins, the Nanten and Daimaru, while the locality of the latter could not be specified. The empirical formulae of two benjaminites based on 22 atoms are (Ag_{2. 74}Cu_{0. 24})_{Σ2. 98}(Bi_{7. 00}Sb_{0. 01})_{Σ7. 01}(S_{10. 89}Se_{1. 12})_{Σ12. 01} (Nanten) and (Ag_{2. 90}Cu_{0. 10})_{Σ3. 00}(Bi_{6. 74}Pb_{0. 18}Sb_{0. 07})_{Σ6. 99}(S_{11. 68}Se_{0.33)Σ12. 01} (Daimaru), leading to the validation of the formula Ag₃Bi₇S₁₂ as the ideal one for benjaminite, and that of matildite based on 4 atoms is Ag_{1. 00}Bi_{1. 00}(S_{1. 78}Se_{0. 22})Σ_{2. 00}. These designate the substitution of Se for S in all of them, where Se is preferentially incorporated into these Ag-Bi sulphosalts. The unit-cell parameters of them and matildite are: a 13. 272, b 4. 037, c 20. 185 Å, and β 103. 16° (Daimaru), a 13. 270, b 4. 040, c 20. 273 Å, and β103. 17° (Nanten); and a 4. 0670, c 18. 996 Å, respectively. The products of Au-Ag mineralization in the Ikuno polymetallic vein-type deposits also occur as such Ag-Bi sulfosalts as benjaminite and matildite, in addition to pavonite, “treasurite derivative” and “electrum” with cassiterite in the polymetallic zone, and also do as “electrum”, acanthite, and pyrargyrite-proustite in the Au-Ag zone. The significant quantity of the Ag-Bi sulfosalts does not violate the zoning occupying the outermost part of the zonal distribution of ores in the deposits.     

Geological relationship between Anyui Metamorphic Complex and Samarka terrane,Far East Russia

The Anyui Metamorphic Complex (AMC) of Cretaceous age is composed of metachert, schist, gneiss, migmatite and ultramafic rocks, and forms a dome structure within the northernmost part of the Jurassic accretionary complex of the Samarka terrane. The two adjacent geological units are bounded by a fault, but the gradual changes of grain size and crystallinity index of quartz in chert and metachert of the Samarka terrane and the AMC, together with the gradual lithological change, indicate that at least parts of the AMC are metamorphic equivalents of the Samarka rocks. Radiolarian fossils from siliceous mudstone of the Samarka terrane indicates Tithonian age (uppermost Jurassic), and hence, form a slightly later accretion. This signifies that the accretionary complex in the study area is one of the youngest tectonostratigraphic units of the Samarka terrane. The relationship between the Samarka terrane and AMC, as well as their ages and lithologies, are similar to those of the Tamba–Mino–Ashio terrane and Ryoke Metamorphic Complex in southwest Japan. In both areas the lower (younger) part of the Jurassic accretionary complexes were intruded and metamorphosed by Late Cretaceous granitic magma. Crustal development of the Pacific‐type orogen has been achieved by the cycle of: (i) accretion of oceanic materials and turbidites derived from the continent; and (ii) granitic intrusion by the next subduction and accretion events, accompanied by formation of high T/P metamorphic complexes.     

Short-Term Stability Evaluation of an Embankment Constructed on Marine Clay Foundation at Kobe Airport

This article introduces the application of a stability analysis method that accounts for strength anisotropy on the embankment constructed at the Kobe airport. Shear strength anisotropy is induced by the in-situ state of stress along a potential slip surface of the embankment. In addition, the effects of the shearing rate on the undrained shear strength of the marine clay are examined in detail based on the results of a series of constant-volume direct shear box (DSB), triaxial compression (TC), and triaxial extension (TE) tests varying shearing rates. The most critical slip surface was selected from the deterministic slope stability analysis using unconfined compression tests of undisturbed clay samples from the field. For the most critical slip surface, the potential factor of safety of the embankment is estimated to be within the range of 1.21 to 1.28, as indicated by the results of the stability analyses using the strengths obtained from the DSB, TC, and TE tests and varying shearing rates.     

Heavy oil exposure increases viral production in natural marine bacterial populations

This study examined whether heavy oil (HO) increases viral production and how that change may affect the marine bacterial community. The addition of a relatively low concentration (10 μg/mL) of HO to seawater resulted in the highest degree of viral lysis. Although the composition of the bacterial community did not change upon the viral lysis in terms of the taxa present, the relative abundance of the γ-Proteobacteria family Alteromonadaceae decreased (by 10 %) after the HO exposure, implying that the selective lysis by viruses and induced prophages may be responsible for changes in the composition of the bacterial community.     

Examination of drag coefficient with special reference to the windsea Reynolds number: Conditions with counter and mixed swell

The effect of swell on the drag coefficient, C _D, observed at the Hiratsuka Tower Station, presented by Suzuki et al. (1998, 2002), has been investigated. C _D increases sharply with the windsea Reynolds number, R _B, when there is a counter swell against the windsea direction, and only gradually when the swell comes from a mixture of directions. In cases where 2-D wave spectra were unavailable (1998, and others), swells showed a scattering effect compared with the pure windsea case on the C _D-R _B Diagram. R _B is a useful parameter for investigating the effect of swells and further systematic accumulation of appropriate data is needed.     

High Ash Content in Net-Plankton Samples from Shallow Coastal Water: Possible Source of Error in Dry Weight Measurement of Zooplankton Biomass

Annual examination of net-plankton biomass in dry weight, ash-free dry weight, organic carbon, and nitrogen weight at the Manazuru harbor, central Japan revealed that net-plankton samples from shallow coastal water contained considerable amount of ash (53±13% of dry weight) which would be caused by contamination of inorganic materials from re-suspendion of sediments, terrestrial runoff and chain-forming diatoms. Therefore, in coastal water, dry weight is inadequate fro determination of zooplankton biomass in volving the possibility of over-estimation. Practical estimation of net-plankton biomass in shallow coastal waters, ash-free dry weight, organic carbon, and/or nitrogen are more adequate.