In this paper, the inverse problem of resistivity retrieval is addressed in the frame of electrical resistance tomography (ERT). The ERT data is a set of measurements of the dc resistances between pairs of electrodes in contact with the conductor under investigation. This paper is focused on a non-iterative inversion method based on the monotonicity of the resistance matrix (and of its numerical approximations). The main features of the proposed inversion method are its low computational cost requiring the solution of O(n) direct problems, where n is the number of parameters used to represent the unknown resistivity, and its very simple numerical implementation.

In the present Letter, we demonstrate how the design of metallic nanoparticle arrays with large electric field enhancement can be performed using the basic paradigm of engineering, namely the optimization of a well-defined objective function. Such optimization is carried out by coupling a genetic algorithm with the analytical multiparticle Mie theory. General design criteria for best enhancement of electric fields are obtained, unveiling the fundamental interplay between the near-field plasmonic and radiative photonic coupling. Our optimization approach is experimentally validated by surface-enhanced Raman scattering measurements, which demonstrate how genetically optimized arrays, fabricated using electron beam lithography, lead to order of ten improvement of Raman enhancement over nanoparticle dimer antennas, and order of one hundred improvement over optimal nanoparticle gratings. A rigorous design of nanoparticle arrays with optimal field enhancement is essential to the engineering of numerous nanoscale optical devices such as plasmon-enhanced biosensors, photodetectors, light sources and more efficient nonlinear optical elements for on chip integration.

The early morphologic involvement of the GCL+IPL and INL+OPL layers in ARM eyes, as revealed by the ASA, could be related to early anatomic changes described in the inner retina of ARM eyes. This finding may represent a morphologic correlation to the deficits in postreceptoral retinal function in ARM eyes.

Eddy current-based techniques have been investigated for the inspection of embedded cracks under fastener heads in riveted structures. However, these techniques are limited in their ability to detect cracks that are not perpendicular to induced current flows. Further, the presence of a steel fastener of high permeability produces a strong signal that masks relatively smaller indication from a crack. In this paper, a rotating electromagnetic field is designed to rotate the applied magnetic fields and related eddy currents electrically so that the sensor shows uniform sensitivity in detecting cracks in all radial directions around fastener sites. Giant magnetoresistive sensors are employed to image the normal component of this rotating field, to detect different crack orientations at aluminum and ferromagnetic fastener sites. Numerical model-based studies and experimental validation are presented.Index Terms-Eddy current, giant magnetoresistive sensor, rotating electromagnetic field, fastener hole inspection, NDE.