P B Stephens

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[1] Objective quantification of model performance based on metrics helps us evaluate the current state of space physicsmodeling capability, address differences among variousmodeling approaches, and track model improvements over time. The Coupling, Energetics, and Dynamics of Atmospheric Regions (CEDAR) Electrodynamics Thermosphere Ionosphere (ETI) Challenge(More)
A multipass optical parametric amplif ier is pumped by a 250-kHz microjoule-level Ti:sapphire regenerative amplif ier system. Tuning each pass of the amplif ier to provide gain for slightly different spectral regions of a white-light continuum source produces broadband pulses that may be compressed to less than 30 fs.
Three spacecraft for the UK, Turkey and Nigeria were launched together in September 2003, to join Algeria's satellite, AlSat-1, in the Disaster Monitoring Constellation (DMC). Surrey Satellite Technology Ltd. has designed, built and launched the world's first constellation to provide daily global Earth observation coverage at moderate resolution in three(More)
This paper is concerned with on-board intelligent imaging targeted at the Disaster Monitoring Constellation small satellite platform. An Automatic Change Detection System is proposed and its application to the process of flood monitoring and mitigation is outlined. The aim is to provide near real-time information of the changes in flood-affected areas and(More)
The structure of the thermoelectric Zn/sub 4/Sb/sub 3/ is refined using synchrotron X-ray powder diffraction data collected at wavelengths both near to and relatively far from the Zn adsorption edge. In agreement with earlier studies, the compound crystallized in a trigonal structure, space group R~3c with a = 12.2406(3)/spl Aring/, c = 12.4361(3)/spl(More)
An understanding of the mechanical properties of different suture materials is valuable when selecting the most appropriate suture and repair technique. Sutures should be strong, easy to handle and have high knot security. The introduction of suture anchors adds an additional variable regarding the effect of stress risers over the eyelet. Improving the(More)
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