Inverse elastic-wave scattering problems are shown to be ill-posed in general. Standard simplifying assumptions--the first Born approximation, the physical optics approximation, and the stopping power approximation of tomography--are shown to reduce to the same ill-posed mathematical problem, that of inverting a Fourier transform. Practical implications of this fact are illustrated with examples.

We describe the salient features of precise predictions for the processes e + e − → WW → 4f (γ) as obtained with the Monte Carlo generator RacoonWW ‡ , including the complete O(α) electroweak radiative corrections in the double-pole approximation. Numerical results for some distributions are given at the typical linear-collider energy √ s = 500 GeV. Moreover, we study the impact of the non-univ...

Generalized Born (GB) models provide, for many applications, an accurate and computationally facile estimate of the electrostatic contribution to aqueous solvation. The GB models involve two main types of approximations relative to the Poisson equation (PE) theory on which they are based. First, the self-energy contributions of individual atoms are estimated and expressed as "effective Born rad...

Ž . We compute complete including both body and surface waves synthetic seismograms for laterally and vertically Ž . heterogeneous Earth models using the Direct Solution Method DSM . We use the optimally accurate modified operators w derived by Geller and Takeuchi Geller, R.J., Takeuchi, N., 1995. A new method for computing highly accurate DSM x w synthetic seismograms. Geophys. J. Int. 123, 44...

Born-Oppenheimer dynamics is shown to provide an accurate approximation of time-independent Schrödinger observables for a molecular system with an electron spectral gap, in the limit of large ratio of nuclei and electron masses, without assuming that the nuclei are localized to vanishing domains. The derivation, based on a Hamiltonian system interpretation of the Schrödinger equation and stabil...