On the threshold of transport of sand-sized sediment under the combined influence of unidirectional and oscillatory flow

Swansea Bay may be taken as an example of an embayment which has a complex and variable hydrodynamic regime resulting from the interaction of its bathymetry and configuration with an adjacent rectilinear, semidiurnal tidal system and with superimposed oceanic swell and more locally generated seas.Eulerian tidal current observations in Swansea Bay indicated a coastal tidal current pattern which has developed from the main currents along the northern Bristol Channel. The observed pattern consists of an anticlockwise eddy in the western part of the embayment and a zone of divergence on the eastern side, between the eddy and the main offshore flow. Wave data, as represented by refraction diagrams and the distribution of sea bed orbital velocities, have demonstrated that high energy wave conditions prevail over the area. Sediment distribution and transport in Swansea Bay are controlled by tidally and wave-induced current patterns, but are also related to bathymetry and the exposure of relict deposits. However, evidence is presented to suggest that local dredging activities influence the sedimentation processes

High-pT jets in p¯p collisions at s=630 and 1800 GeV

Results are presented from analyses of jet data produced in pp̅ collisions at √s=630 and 1800 GeV collected with the DØ detector during the 1994–1995 Fermilab Tevatron Collider run. We discuss the details of detector calibration, and jet selection criteria in measurements of various jet production cross sections at √s=630 and 1800 GeV. The inclusive jet cross sections, the dijet mass spectrum, the dijet angular distributions, and the ratio of inclusive jet cross sections at √s=630 and 1800 GeV are compared to next-to-leading-order QCD predictions. The order αs3 calculations are in good agreement with the data. We also use the data at √s=1800 GeV to rule out models of quark compositeness with a contact interaction scale less than 2.2 TeV at the 95% confidence level