Abstract: We develop three-dimensional electromagnetic inverse scattering methods to reconstruct buried objects in layered media. The nonlinear inverse problem is solved iteratively via conjugate gradient approach; within each iteration, the problem is linearized by Born and Distorted Born approximations. The forward solution for layered media is provided by the stabilized biconjugate-gradient ...

Multi-level transactions are a variant of open nested transactions in which the subtransactions correspond to operations at different levels of a layered system architecture. The point of multi-level transactions is that the semantics of high-level operations can be exploited in order to increase concurrency. As a consequence, undoing a transaction requires compensation of completed subtransact...

OBJECTIVE Many changes have been initiated in the Dutch hospital sector to optimize health-care delivery: national agenda-setting, increased competition and transparency, a new system of hospital reimbursement based on diagnosis-treatment combinations, intensified monitoring of quality and a multi-layered organizational development programme based on quality improvement collaboratives. The obje...