Fluid flow experiments are being conducted on core specimens of quartz monzonite retrieved from depths of about 1 km at the Desert Peak East EGS site in Churchill County, Nevada. Our immediate goal is to observe permeability evolution in fractures at pressure and temperature conditions appropriate to the Desert Peak geothermal site. Longer term, we aim to evaluate mechanisms that control the evolution of fracture permeability. In the experiments saline water is flowed through an artificial fracture at a constant rate of 0.02 ml/min over a period of several weeks. The constant flow tests are interrupted at selected times for shorter tests in which flow is either stopped or varied between 0 and 2.0 ml/min. The experiments to date were conducted at a confining pressure of 5.5 MPa, pore pressures of 1.38 MPa or 2.07 MPa and temperatures of 167- 169 C. Measurements include differential pressure and electrical resistance across the specimen. The short-term variable flow rate experiments allow us to calculate the effective hydraulic aperture of the fracture at various times during the experiment. Changes in electrical resistivity provide indirect evidence of ongoing mineral dissolution and precipitation processes that are expected to change fracture permeability over time. The early …

We assess how well next generation neutrinoless double beta decay and normal neutrino beta decay experiments can answer four fundamental questions. 1) If neutrinoless double beta decay searches do not detect a signal, and if the spectrum is known to be inverted hierarchy, can we conclude that neutrinos are Dirac particles? 2) If neutrinoless double beta decay searches are negative and a next generation ordinary beta decay experiment detects the neutrino mass scale, can we conclude that neutrinos are Dirac particles? 3) If neutrinoless double beta decay is observed with a large neutrino mass element, what is the total mass in neutrinos? 4) If neutrinoless double beta decay is observed but next generation beta decay searches for a neutrino mass only set a mass upper limit, can we establish whether the mass hierarchy is normal or inverted? We base our answers on the expected performance of next generation neutrinoless double beta decay experiments and on simulations of the accuracy of calculations of nuclear matrix elements.

Livermore Computing is an early and aggressive adopter of parallel file systems including, for example, GPFS from IBM and Lustre for our present Linux systems. As such, we have acquired more than our share of battle scars from encountering bugs in 'bleeding edge' file systems that we have pressed into production to serve our customers' massive I/O requirements. A major role of the Scalable I/O Project is to detect errors before our end users do. In order to do this, we have developed highly parallel test codes to stress and probe potentially weak areas of file system behavior. This paper describes those test programs and how we make use of them.

Effects of W on the creep resistance of two nearly fully lamellar TiAl alloys with 1.0 and 2.0 at.%W have been investigated. In the low stress regime (LS) a nearly quadratic (1.5<n<2) creep behavior was observed. It is found that the addition of W can improve the creep resistance; however, the addition of excess W can result in the formation of {beta} phase, which produces an adverse effect on the creep strength.

Exposure to environmental radiation and the application of new clinical modalities, such as radioimmunotherapy, have heightened the need to understand cellular responses to low dose and low-dose rate ionizing radiation. Many tumor cell lines have been observed to exhibit a hypersensitivity to radiation doses below 50 cGy, which manifests as a significant deviation from the clonogenic survival response predicted by a linear-quadratic fit to higher doses. However, the underlying processes for this phenomenon remain unclear. Using a gel microdrop/flow cytometry assay to monitor single cell proliferation at early times post irradiation, we examined the response of human A549 lung carcinoma, T98G glioma and MCF7 breast carcinoma cell lines exposed to gamma radiation doses from 0 to 200 cGy delivered at 0.18 and 22 cGy/min. The A549 and T98G cells, but not MCF7 cells, showed the marked hypersensitivity at doses <50 cGy. To further characterize the low-dose hypersensitivity, we examined the influence of low-dose radiation on cell cycle status and apoptosis by assays for active caspase-3 and phosphatidylserine translocation (annexin-V binding). We observed that caspase-3 activation and annexin-V binding mirrored the proliferation curves for the cell lines. Furthermore, the low-dose hypersensitivity and annexin-V binding to irradiated A549 and T98G cells were …

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We investigate the impact of water, a polar solvent, on the optical absorption of prototypical silicon clusters with oxygen passivation. We approach this complex problem by assessing the contributions of three factors: chemical reactivity; thermal equilibration and dielectric screening. We find that the silanone (Si=O) functional group is not chemically stable in the presence of water and exclude this as a source of significant red shift in absorption in aqueous environments. We perform first principles molecular dynamics simulations of the solvation of an oxygenated silicon cluster with explicit water molecules at 300 K. We find a systematic 0.7 eV red shift in the absorption gap of this cluster, which we attribute to thermal strain of the molecular structure. Surprisingly, we find no observable screening impact of the solvent, in contrast with consistent blue shifts observed for similarly sized organic molecules in polar solvents. The predicted red shift is expected to be significantly smaller for larger Si quantum dots produced experimentally, guaranteeing that their vacuum optical properties are preserved even in aqueous environments.