In the usual formulation of the Kirchhoff diffraction integral, a scalar field with harmonic time dependence at frequency ω is deduced at the interior of a charge-free volume from knowledge of the field (or its normal derivative) on the bounding surface. In particular, the field is propagated forwards in time from the boundary to the desired observation point. Construct a time-reversed version ...

We examine words w satisfying the following property: if x is a subword of w and |x| is at least k for some fixed k, then the reversal of x is not a subword of w.

1. Universidade Federal Fluminense, Niterói (RJ) Brasil. 2. Universidade Federal do Rio de Janeiro, Rio de Janeiro (RJ) Brasil. 3. Faculdade de Medicina de Petrópolis, Petrópolis (RJ) Brasil. 4. Santa Casa de Misericórdia de Porto Alegre, Porto Alegre (RS) Brasil. 5. Universidade Federal de Ciências da Saúde de Porto Alegre, Porto Alegre (RS) Brasil. A 35-year-old man presented to the emergency...

Introduction: To prevention the healthy tissues from irreversible damages, monitoring the temperature variation of healthy tissues is critical parameter during thermal therapies. Electrical impedance tomography (EIT) is considered as a real time imaging modality for monitoring the temperature but researches show that it suffers from low temperature resolution. In this study usi...

pregabalin (prg) is a new antiepileptic drug and aceclofenac (ace) is a potent non-steroidal anti-inflammatory drug. these drugs in combination are used for treatment of partial seizures and neuropathic pains. a simple and precise assay method by rp-hplc was developed and validated for estimation of prg and ace in acenac-n tablet. analyses of commercial tablet, acenac-n were performed using jas...

a precise and feasible reversed-phase high-performance liquid chromatographic method for the determination of an antipsychotic drug quetiapine fumarate (qtf) in pharmaceuticals and spiked human urine sample has been developed and validated. the analysis was carried out using a ods (250 mm × 4.6 mm i.d., 5 µm particle size) chromatopack column. mobile phase containing a mixture of acetonitrile a...

The aim of this paper is to introduce the time reversed absorbing conditions (TRAC) in time reversal methods. These new boundary conditions enable one to “recreate the past” without knowing the source which has emitted the signals that are back-propagated. This new method does not rely on any a priori knowledge of the physical properties of the inclusion. We prove an energy estimate for the res...

There is mounting evidence that there are three parallel streams of visual motion computation—firstand second-order systems that are primarily monocular and a third-order binocular system (Lu & Sperling, 1995a, 1995b, 1996c). The first-order system extracts motion from drifting luminance modulations, and the secondorder system extracts motion from drifting texture contrast modulations. These pr...