We investigate the observed correlation between the 2-10 keV X-ray luminosity (in unit of the Eddington luminosity; l(X) L-X/L-Edd) and the photon index (Gamma) of the X-ray spectrum for both black hole X-ray binaries (BHBs) and active galactic nuclei (AGNs). We construct a large sample, with 10(-9) less than or similar to l(X) less than or similar to 10(-1). We find that Gamma is positively and negatively correlated with l(X) when l(X) greater than or similar to 10(-3) and 10(-65) less than or similar to l(X) less than or similar to 10(-3), respectively, while Gamma is nearly a constant when l(X) less than or similar to 10(-6.5). We explain the above correlation in the framework of a coupled hot accretion flow-jet model. The radio emission always comes from the jet while the X-ray emission comes from the accretion flow and jet when l(X) is above and below 10(-6.5), respectively. More specifically, we assume that with the increase of mass accretion rate, the hot accretion flow develops into a clumpy and further a disc-corona two-phase structure because of thermal instability. We argue that such kind of two-phase accretion flow can explain the observed positive correlation.

A new diamond cell with extreme apertures is described. It is tailored for a large variety of neutron scattering techniques such as inelastic neutron scattering and single-crystal diffraction both at the Spallation Neutron Source (SNS) and the High Flux Isotope Reactor at the Oak Ridge National Laboratory. Simple springs enable forces of over 10 metric tons to be clamped in for low-temperature measurements. At present, low-cost polycrystalline diamond (Versimax((R))) pressure anvils are used. We predict a routine pressure regime up to 20GPa with sample volumes of approximate to 0.5mm(3). Future use of large CVD single-crystal diamond anvils will significantly expand this pressure range. We show examples for measurements at the SNAP, VISION and CORELLI beamlines of the SNS.

A diamond cell optimized for single-crystal neutron diffraction is described. It is adapted for work at several of the single-crystal diffractometers of the Spallation Neutron Source and the High Flux Isotope Reactor at the Oak Ridge National Laboratory (ORNL). A simple spring design improves portability across the facilities and affords load maintenance from offline pressurization and during temperature cycling. Compared to earlier prototypes, pressure stability of polycrystalline diamond (Versimax (R)) has been increased through double-conical designs and ease of use has been improved through changes to seat and piston setups. These anvils allow similar to 30%-40% taller samples than possible with comparable single-crystal anvils. Hydrostaticity and the important absence of shear pressure gradients have been established with the use of glycerin as a pressure medium. Large single-crystal synthetic diamonds have also been used for the first time with such a clamp-diamond anvil cell for pressures close to 20 GPa. The cell is made from a copper beryllium alloy and sized to fit into ORNL's magnets for future ultra-low temperature and high-field studies. We show examples from the Spallation Neutron Source's SNAP and CORELLI beamlines and the High Flux Isotope Reactor's HB-3A and IMAGINE beamlines. Published by AIP Publishing.

Gmsh for Python Copyright: Open Access

Gmsh for Python Copyright: Open Access

Gmsh for Python Copyright: Open Access

Gmsh for Python Copyright: Open Access

Gmsh for Python Copyright: Open Access

Gmsh for Python Copyright: Open Access

The validation of numerical models for large lakes is difficult because of sparse field observations. In this study, a Froude-Rossby scaled physical model of Lake Ontario, North America, is used to support numerical simulations. Experimental data are consistent with available field observations and provide a more comprehensive view of lake-wide features that include, in the absence of wind, strong eastward flows along both northern and southern shorelines, a large cyclonic gyre in the Rochester basin, and smaller midlake cyclonic eddies. With a west wind (most common direction), a well-defined westward flow in the middle of the lake separates an anticyclonic gyre in the north from a cyclonic gyre in the south. A review of numerical models shows that most models can capture general features of these observed patterns but do not always reproduce all details, especially in nearshore regions. A numerical model based on the Environmental Fluid Dynamics Code (EFDC), with a 200-m resolution in nearshore regions, is developed.