Comparison of exit time moment spectra for extrinsic metric balls

We prove explicit upper and lower bounds for the L1-moment spectra for the Brownian motion exit time from extrinsic metric balls of submanifolds Pm in ambient Riemannian spaces Nn. We assume that P and N both have controlled radial curvatures (mean curvature and sectional curvature, respectively) as viewed from a pole in N. The bounds for the exit moment spectra are given in terms of the corresponding spectra for geodesic metric balls in suitably warped product model spaces. The bounds are sharp in the sense that equalities are obtained in characteristic cases. As a corollary we also obtain new intrinsic comparison results for the exit time spectra for metric balls in the ambient manifolds Nn themselves

Robust 3D pose estimation and efficient 2D region-based segmentation from a 3D shape prior

©2008 Springer-Verlag Berlin Heidelberg. The original publication is available at www.springerlink.com.Presented at the 10th European Conference on Computer Vision, Marseille, France, October 12-18, 2008.DOI: 10.1007/978-3-540-88688-4_13In this work, we present an approach to jointly segment a rigid object in a 2D image and estimate its 3D pose, using the knowledge of a 3D model. We naturally couple the two processes together into a unique energy functional that is minimized through a variational approach. Our methodology differs from the standard monocular 3D pose estimation algorithms since it does not rely on local image features. Instead, we use global image statistics to drive the pose estimation process. This confers a satisfying level of robustness to noise and initialization for our algorithm, and bypasses the need to establish correspondences between image and object features. Moreover, our methodology possesses the typical qualities of region-based active contour techniques with shape priors, such as robustness to occlusions or missing information, without the need to evolve an infinite dimensional curve. Another novelty of the proposed contribution is to use a unique 3D model surface of the object, instead of learning a large collection of 2D shapes to accommodate for the diverse aspects that a 3D object can take when imaged by a camera. Experimental results on both synthetic and real images are provided, which highlight the robust performance of the technique on challenging tracking and segmentation applications

PHOTOLUMINESCENCE OF LIFNAF FILMS AT ROOM-TEMPERATURE

In this paper we present the results of the photoluminescence spectra of multilayer LiF:NaF films colored by low energy (3 keV) electron beams. We show that dielectric multilayered films can be used in the design of new materials with optical properties that cannot be matched by bulk materials

CRYSTALLINE PROPERTIES AND COLOR-CENTERS IN ALKALI-HALIDE THIN-FILMS

Thin films of KCl, KBr, RbCl have been obtained by thermal evaporation on amorphous substrates with different deposition parameters. The crystalline structure and orientation have been determined, and the films resulted to be policrystals with high uniformity of orientation. Production of colour centres, achieved by irradiation with low-energy electrons, leads to F center concentrations barely observed in large crystals. The colouration kinetics is similar to that in the bulk, and shows after a maximum an exponential decay at high doses because of centre aggregation coupled to thermal effects. The films exhibit a bleaching process of the colour centres at room temperature, whose kinetics depends on the irradiation damage

NaF films: Growth properties and electron beam induced defects

Polycrystalline NaF films were grown by e-beam assisted physical evaporation on amorphous silica substrates kept, during film growth, at constant temperatures ranging from 40 degrees C to 400 degrees C. The structural characterization of the films was performed by X-ray diffraction and by scanning electron microscopy. Irradiating the films with a 15 keV electron beam induced the formation of F and F-aggregate colour centres stable at room temperature. Absorption and photoemission measurements were performed and indicated a dependence of coloration on the deposition conditions