Area and length minimizing flows for shape segmentation

To Appear in the IEEE Transactions on Image Processing. Anumber of active contour models have been proposed which unify the curve evolution framework with classical energy minimization techniques for segmentation, such as snakes. The essential idea is to evolve a curve (in 2D) or a surface (in 3D) under constraints from image forces so that it clings to features of interest in an intensity image. Recently the evolution equation has been derived from rst principles as the gradient ow that minimizes a modi ed length functional, tailored to features such as edges. However, because the ow may be slow toconverge in practice, a constant (hyperbolic) term is added to keep the curve/surface moving in the desired direction. In this paper, we derive a modi cation of this term based on the gradient ow derived from a weighted area functional, with image dependent weighting factor. When combined with the earlier modi ed length gradient ow we obtain a pde which o ers a number of advantages, as illustrated by several examples of shape segmentation on medical images. In many cases the weighted area ow may be used on its own, with signi cant computational savings

Determination of reference values for optical properties of liquid phantoms based on Intralipid and India ink

A multi-center study has been set up to accurately characterize the optical properties of diffusive liquid phantoms based on Intralipid and India ink at near-infrared (NIR) wavelengths. Nine research laboratories from six countries adopting different measurement techniques, instrumental set-ups, and data analysis methods determined at their best the optical properties and relative uncertainties of diffusive dilutions prepared with common samples of the two compounds. By exploiting a suitable statistical model, comprehensive reference values at three NIR wavelengths for the intrinsic absorption coefficient of India ink and the intrinsic reduced scattering coefficient of Intralipid-20% were determined with an uncertainty of about 2% or better, depending on the wavelength considered, and 1%, respectively. Even if in this study we focused on particular batches of India ink and Intralipid, the reference values determined here represent a solid and useful starting point for preparing diffusive liquid phantoms with accurately defined optical properties. Furthermore, due to the ready availability, low cost, long-term stability and batch-to-batch reproducibility of these compounds, they provide a unique fundamental tool for the calibration and performance assessment of diffuse optical spectroscopy instrumentation intended to be used in laboratory or clinical environment. Finally, the collaborative work presented here demonstrates that the accuracy level attained in this work for optical properties of diffusive phantoms is reliable. (C) 2014 Optical Society of Americ

Coherent and Squeezed States: Introductory Review of Basic Notions, Properties, and Generalizations

A short review of the main properties of coherent and squeezed states is given in introductory form. The efforts are addressed to clarify concepts and notions, including some passages of the history of science, with the aim of facilitating the subject for nonspecialists. In this sense, the present work is intended to be complementary to other papers of the same nature and subject in current circulation.Comment: 50 pages, misprints corrected, some new references included. To appear in "Integrability, Supersymmetry and Coherent States. A Volume in Honor of Professor Veronique Hussin