This paper presents a stochastic differential equation approach to multiphase flow, a typical example of which is flow in the unsaturated domain. Specifically, a two phase problem is studied which consists of a wetting phase and a nonwetting phase. The approach given results in a nonlinear stochastic differential equation describing the position of the non-wetting phase fluid particle. The nonl...

Chlorinated solvents in the subsurface are a widespread problem with thousands of impacted sites in the United States. A large body of literature exists that evaluates treatment of chlorinated solvents using granular zero valent iron, which has been shown to treat chlorinated solvents via reductive dechlorination. Much of this literature is conducted within the context of permeable reactive bar...

458 Small-scale physical models have been used for almost two centuries to investigate a wide range of large-scale subsurface processes (Hall, 1815; Daubrée, 1879; Cadell, 1888). In most cases, the experiments were not analyzed quantitatively, and the purported similarities between the model system and the fullscale system of interest are based on qualitative and/or visual characteristics alone...

With rapid new technological development during the past 50 years, aerial photos have been increasingly and commonly used not only in geographic information systems but also in various spatially related applications. Many municipalities and government agencies have constructed aerial photo databases all over the world. Keeping these databases up to date is the most important part of making them...

the same mathematical form, regardless of the nature and number of fluid components and phases. MULNumerical simulation has become a widely practiced and accepted KOM was a research code that served as a test bed for technique for studying flow and transport processes in the vadose developing much of the approaches and methodology zone and other subsurface flow systems. This article discusses a...

Heterogeneous granular sediments—sands and gravels —form the most important water-supply aquifers in many areas of North America. In the past 60 years many such aquifers have become contaminated with nonaqueous phase liquids (NAPLs) and the dissolved phases associated with them. These include glacial outwash deposits in New England, Ohio, and Ontario, the floodplain alluvium along the Columbia ...

Occurrence of diarrhea following initially successful treatment l i i s a major shortcoming in the treatment of Clostridium difficile-associated diarrhea (CDAD). Sustained response is a clinical endpoint proposed to account for differences among treatment agents with respect to a combination of initial response/cure and recurrence. Until recently, vancomycin was the only FDA-approved treatment ...

One of the main problems associated with remediation of chlorinated solvent groundwater contamination is the presence of NAPLs in the source zone. NAPLs are often better treated through solvent extraction, surfactant washing, or vapor extraction than through bioremediation. Removal of NAPL through solvent extraction would likely leave a substantial residual of both the extraction solvent and th...

S. A. Tishkoff et al. (1) provide an intriguing analysis of human genetic variation at the CD4 locus. We are concerned, however, that their data do not provide significant support for the estimate that modern humans first emerged from Africa in the last 100,000 years. It appears that a robust estimate of this migration time will require the use of numerous loci. The estimate, which is predicate...