Bronchopulmonary Dysplasia

Hospitalizations for respiratory syncytial virus bronchioliti

Hierarchical Hidden Markov Model in Detecting Activities of Daily Living in Wearable Videos for Studies of Dementia

International audienceThis paper presents a method for indexing activities of daily living in videos obtained from wearable cameras. In the context of dementia diagnosis by doctors, the videos are recorded at patients' houses and later visualized by the medical practitioners. The videos may last up to two hours, therefore a tool for an efficient navigation in terms of activities of interest is crucial for the doctors. The specific recording mode provides video data which are really difficult, being a single sequence shot where strong motion and sharp lighting changes often appear. Our work introduces an automatic motion based segmentation of the video and a video structuring approach in terms of activities by a hierarchical two-level Hidden Markov Model. We define our description space over motion and visual characteristics of video and audio channels. Experiments on real data obtained from the recording at home of several patients show the difficulty of the task and the promising results of our approach

Raman scattering by the longitudinal optical phonon in InN: Wave-vector nonconserving mechanisms

We have studied plasmon-longitudinal optical (LO) phonon coupled modes by means of Raman scattering in n-type InN layers grown by metalorganic vapor phase epitaxy, for carrier densities in the range of 10(19) cm(-3). A strong mode is observed near the frequency of the A(1)(LO) phonon, despite the high conductivity of the films. It is suggested that the main origin which can be invoked for an effective decoupling of the LO phonon from the plasmon is the participation to the scattering of phonons with wave vectors larger than the Thomas-Fermi wave vector. The line shape of the LO mode is calculated using the Lindhard-Mermin dielectric function taking into account finite wave-vectors, for various light scattering processes. We find that the charge density fluctuations mechanism is involved as the main scattering mechanism in n-type InN, at least for the investigated excitation energies in the 2.54-1.89 eV range. The breakdown of the wave-vector conservation is assigned to electron elastic scattering by impurities

Strain-induced correlations between the phonon frequencies of indium nitride

International audienceUsing measurements of phonons frequencies in large size InN quantum dots deposited by Metal-organic vapor phase epitaxy, we found these frequencies to experience a blue shift with increasing compression. Next we show that all the phonon frequencies reported in the literature are correlated to the strain state of InN and are, within the experimental uncertainty, consistent with each other. (C) 2004 WILEY-VCH Verlag GmbH & Co. KGaA. Weinheim

Absorption and Raman scattering processes in InN films and dots

International audienceWe demonstrate that the phonon frequencies that are reported in the literature for indium nitride (InN), films are all consistently correlated to the strain state of the material. Raman spectroscopy measurements and X-ray investigations of large size InN quantum dots grown on c-plane GaN are combined, which show these frequencies to experience a blue shift with increasing compression. The InN dots are weakly strained, most probably due to the formation of dislocations at the InN/GaN interface. We report the observation of a broad absorption in the 1.25 eV region that is typical of thin InN films. Such a feature we attribute to light absorption at the energy of the fundamental direct band gap of InN, while we attribute the low energy 650-800 meV photoluminescence to an extrinsic recombination process analogous to the processes that produce the blue band in AlN and the yellow band in GaN. (C) 2004 Elsevier B.V. All rights reserved