Effect of surface wave propagation in a four-layered oceanic crust model

Dispersion of Rayleigh type surface wave propagation has been discussed in four-layered oceanic crust. It includes a sandy layer over a crystalline elastic half-space and over it there are two more layers—on the top inhomogeneous liquid layer and under it a liquid-saturated porous layer. Frequency equation is obtained in the form of determinant. The effects of the width of different layers as well as the inhomogeneity of liquid layer, sandiness of sandy layer on surface waves are depicted and shown graphically by considering all possible case of the particular model. Some special cases have been deduced, few special cases give the dispersion equation of Scholte wave and Stoneley wave, some of which have already been discussed elsewhere.     

Polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans in sediments from Hong Kong

Concentrations of 2,3,7,8-substituted polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) were determined in 14 sediment samples collected from four sites in the Mai Po Marshes Nature Reserve (within a RAMSAR Site) and from another six sites in Victoria Harbour and along the Hong Kong coastline. Elevated levels of PCDDs, and particularly OCDD, were detectable in all samples collected from the Mai Po Marshes and five of the six sites. In contrast to PCDDs, PCDFs were mainly found in sediment samples collected from industrial areas (Kwun Tong and To Kwa Wan) in Victoria Harbour. PCDD/F levels and congener profiles in the samples from the Mai Po Marshes Nature Reserve in particular show strong similarities to those reported in studies which have attributed similar elevated PCDD concentrations to nonanthropogenic PCDD sources.     

English Jurassic Limestone Country: Stroud,Central Cotswolds

The area around Stroud, a small English market town perched on the steep west‐facing Cotswold escarpment, offers some of the most dramatic outcrops of Jurassic limestone in the UK. From sweeping vistas of the Severn Vale, to the deeply wooded river valleys that indent the escarpment, its landscape is undeniably one of the area's greatest assets. Recently, the geology and physiography of the landscape has been drawn into close focus by several notable UK media stories: protests against hydraulic fracturing (fracking) in the underlying Lias clays; landslides causing weeks of repeated disruption across the Cotswold road and railway networks; and the recent death of a local engineer in a pit collapse of Fuller's Earth. In order to understand these stories in greater depth, it is useful to consider the story of Stroud's unique physical setting.     

Terrestrial age measurements using natural thermoluminescence of a drained zone under the fusion crust of Antarctic ordinary chondrites

Abstract— Miono et al. (1990) and Miono and Nakanishi (1994) have proposed that the build‐up of natural thermoluminescence (TL) in a drained layer directly below the meteorite fusion crust can be used to determine terrestrial ages of meteorites in the 40 to 200 ka range. We have measured the natural TL of the drained layer of 15 meteorites. The data indicate that this technique could be used to determine terrestrial ages of meteorites with ages <200 ka, after which TL equilibrium is reached. Comparison of TL build‐up with terrestrial ages for a suite of Antarctic meteorites suggests that the meteorites have been exposed to temperatures of 0 to 5 °C. The close correspondence between natural TL levels and surface exposure TL growth curves suggest that Allan Hills meteorites with ages <200 ka have spent a significant portion of their terrestrial history exposed on the ice surface, rather than being buried in the ice sheet. The technique is, however, sensitive to thermal history; and, for Antarctic meteorites with terrestrial ages <200 ka, natural TL of the drained zone largely reflects exposure on the ice surface.     

Effects of cloud types on cloud-radiation interaction over the Asian monsoon region

This paper quantifies the sensitivity of radiation budget quantities to different cloud types over the Asian monsoon region using the International Satellite Cloud Climatology Project. Multiple regression was used to estimate the radiative effects of individual cloud type. It was observed that the regression performed better when the solution was constrained with clear sky fluxes, which is evident by an improvement in R ² statistics. The sensitivity coefficients calculated for the Asian monsoon region reveal that, while the LWCRCF and SWCRF will be most vulnerable to changes in cloud cover of deep convective clouds, NETCRF will be susceptible to changes in the nimbostratus clouds. Although the cloud radiative forcing of individual cloud types are found to be similar in sign to previous global findings, their magnitudes are found to vary. It is seen that cirrus clouds play an important role in governing the radiative behavior of this region.     

A SPATIALLY-VARYING PARAMETER MODEL OF AFDC PARTICIPATION: EMPIRICAL ANALYSIS USING THE EXPANSION METHOD*

Spatial variation in the importance of determinants of participation in the Aid to Families with Dependent Children program (AFDC) is investigated for the U.S. Casetti's Expansion Method is applied to the two-dimensional space domain by making the model's parameters a function of state x–y centroids. The spatially-varying parameter model suggests that the black population's association with participation is lowest in the Southeast and Northwest and greatest in the Southwest and Northeast.     

Evaluating Natural Attentuation with Spreadsheet Analytical Fate and Transport Models

Superposition techniques can extend the capabilities of relatively simple analytical fate and transport models. Complex source geometries, simple aquifer boundaries, and electron acceptor limited biodegradation can be simulated by using superposition techniques in computer spreadsheets. Spreadsheet models are an easily used tool for interpreting sampling results and for estimating attenuation and degradation rates in relatively homogeneous aquifers. Analytical spreadsheet models are based on the Domenico analytical model and can provide results that are in close agreement with the numerical model UIOPLUMH II.