With the growing number of fatalities resulting from the 100 or so cancer-related diseases, new enabling tools are required to provide extensive molecular profiles of patients to guide the clinician in making viable diagnosis and prognosis. Unfortunately with cancer-related diseases, there is not one molecular marker that can provide sufficient information to assist the clinician in making effective prognoses or even diagnoses. Indeed, large panels of markers must typically be evaluated that cut across several different classes (mutations in certain gene fragments--DNA; over/under-expression of gene activity as monitored by messenger RNAs; the amount of proteins present in serum or circulating tumor cells). The classical biosensor format (dipstick approach for monitoring the presence of a single element) is viewed as a valuable tool in many bioassays, but possesses numerous limitations in cancer due primarily to the single element nature of these sensing platforms. As such, if biosensors are to become valuable tools in the arsenal of the clinician to manage cancer patients, new formats are required. This review seeks to provide an overview of the current thinking on molecular profiling for diagnosis and prognosis of cancers and also, provide insight into the current state-of-the-art in the biosensor field and new strategies that must be considered to bring this important technology into the cancer field.

[1] Using transparent microfluidic cells to study the twophase properties of a synthetic porous medium, we establish that the interfacial area per volume between nonwetting and wetting fluids lifts the ambiguity associated with the hysteretic relationship between capillary pressure and saturation in porous media. The interface between the nonwetting and wetting phases is composed of two subsets: one with a unique curvature determined by the capillary pressure, and the other with a distribution of curvatures dominated by disjoining pressure. This work provides experimental support for recent theoretical predictions that the capillary-dominated subset plays a role analogous to a state variable. Any comprehensive description of multiphase flow properties must include this interfacial area with the traditional variables of pressure and fluid saturation.

A goal of subsurface geophysical monitoring is the detection and characterization of fracture alterations that affect the hydraulic integrity of a site. Achievement of this goal requires a link between the mechanical and hydraulic properties of a fracture. Here we present a scaling relationship between fluid flow and fracture-specific stiffness that approaches universality. Fracture-specific stiffness is a mechanical property dependent on fracture geometry that can be monitored remotely using seismic techniques. A Monte Carlo numerical approach demonstrates that a scaling relationship exists between flow and stiffness for fractures with strongly correlated aperture distributions, and continues to hold for fractures deformed by applied stress and by chemical erosion as well. This new scaling relationship provides a foundation for simulating changes in fracture behaviour as a function of stress or depth in the Earth and will aid risk assessment of the hydraulic integrity of subsurface sites.

The photorefractive properties of semi-insulating AlGaAs-GaAs multiple quantum wells are described for the transverse Franz-Keldysh geometry with the electric field in the plane of the quantum wells. Combining the strong electroabsorption of quantum-confined excitons with the high resistivity of semi-insulating quantum wells yields large nonlinear optical sensitivities. The photorefractive quantum wells have effective nonlinear optical sensitivities of n2 103 cm 2 /W and a2/ao =: 10 4 cm 2 /W for applied fields of 10 kV/cm. Photorefractive gains approaching 1000 cm-' have been observed in two-wave mixing under dc electric fields and stationary fringes. The transverse Franz-Keldysh geometry retains the general transport properties and behavior of conventional bulk photorefractive materials. The resonant excitation of free electrons and holes in the quantum wells leads to novel behavior associated with electron-hole competition. We demonstrate that under resonant excitation of electrons and holes the device resolution is fundamentally limited by diffusion lengths but is insensitive to long drift lengths.

MEL LOCH ET AL quality single crystals. These materials are arsenides such as GaAs, AIGaAs, and InGaAs containing arsenic clusters. The composites are formed by incorporating excess arsenic in the semiconductor, which per cipitates in the anneal. The incorporation of the excess arsenic is accomplished by molecular beam epitaxy at low substrate temperatures. The cluster density can be controlled with the coarsening annealing. The positioning of the clusters can be controlled with heterojunctions and doping. These composites exhibit several interesting properties, including high-resistivity, appreciable optical absorption below the band gap of the semiconductor matrix material, a large electro-optic effect, and very short carrier lifetimes.