Photorefractive incoherent-to-coherent optical converter

Photorefractive materials have been extensively used in recent years as real-time recording media for optical holography.(^1,2) One prospective application of real-time holography is in the area of optical information processing; for example, the correlation between two mutually incoherent images has recently been demonstrated in real time in a four-wave mixing geometry. (^3) Often, however, the information to be processed exists only in incoherent form. High performance spatial light modulators(^4) are thus necessary in many optical information processing systems to convert incoherent images to coherent replicas for subsequent processing. We report in this Communication the successful demonstration of real-time incoherent-to-coherent images transduction through the use of holographic recording in photorefractive crystals. Several possible configurations and experimental results are presented

Nonperturbative Analysis of the Harmonic Oscillator with a Time-Dependent Frequency

We apply the Floquet theorem and the resonating averages method to solve the Schrödinger equation of the harmonic oscillator whose frequency varies periodically with time. We determine its Floquet states and its corresponding wave functions. The formalism provides an efficiency tool for analyzing the various transition probabilities as well as the uncertainty relation of the system. The effect of a periodic external force on the Floquet states and the two-photon algebra realization are shortly discussed.We apply the Floquet theorem and the resonating averages method to solve the Schrödinger equation of the harmonic oscillator whose frequency varies periodically with time. We determine its Floquet states and its corresponding wave functions. The formalism provides an efficiency tool for analyzing the various transition probabilities as well as the uncertainty relation of the system. The effect of a periodic external force on the Floquet states and the two-photon algebra realization are shortly discussed

Adaptive Heterodyne Interferometer for Ultrasonic NDE

For NDE applications, the remote generation and detection of ultrasound by laser present many advantages over traditional piezo-electric based methods. They provide nonintrusive, point generation and detection with a large frequency bandwidth. For example, it can be used on surfaces of complex geometry and elevated temperature on a production line. Ultrasound generation using absorption of pulse laser energy is well known. Various interferometers for optical detection of ultrasound have been described in the literature [1]. In order for the interferometer to be attractive for NDE applications, the interferometer must also be able to operate, without loss of sensitivity, in an environment where large amplitude low frequency vibrations are generally present. Furthermore, the interferometer must be able to achieve a good sensitivity on rough surfaces. The laser light reflected on a rough surface is characterized by speckles. The random intensity and phase distributions of these speckles require the use of interferometer with large étendue. In addition, the possibility of using an optical fiber in the path of the probe beam without loss in the interferometer sensitivity is highly desirable for applications where access to the specimen is limited. The confocal Fabry-Pérot interferometer [1] has been shown to be well adapted for NDE applications. Unfortunately, since the elimination of the optical side-bands is based on the optical filtering action of the confocal cavity, it is sensitive mostly to high frequencies for a reasonable cavity size, typically above 1MHz for a 1 meter cavity length

Angiodysplasies des maxillaires de l’enfant

Les angiodysplasies des maxillaires sont des affections rares et graves. Leur mauvais pronostic est surtout lié aux complications hémorragiques redoutables, dues le plus souvent à des extractions dentaires abusives sans examens radiologiques préalables. L’angio-IRM a permis d’une manière non invasive une meilleure connaissance de ces lésions en étudiant leur angio-architecture et leur hémodynamique. Jadis, le seul traitement efficace consistait en une exérèse chirurgicale mutilante entraînant des complications esthétiques et fonctionnelles sévères avec une morbidité importante. Actuellement, la radiologie interventionnelle a révolutionné la prise en charge grâce à l’artériographie hypersélective et àla découverte de nouveaux matériaux d’obturation plus faciles à manier. L’embolisation hypersélective est devenue l’arme de première intention en raison de son caractère conservateur et de son faible taux de  complications. Le but de ce travail est de rappeler les différents aspects étiopathogéniques, cliniques et para cliniques des angiodysplasieset de définir l’attitude thérapeutique.Mots clefs : angiodysplasie, embolisation, chirurgie

Analysis of Tunisian date palm germplasm using simple sequence repeat primers

Inter Simple Sequence Repeat (ISSR) markers involve polymerase chain reaction (PCR) amplification of DNA using a single primer composed of a microsatellite sequence. ISSR technology rapidly reveals high polymorphic fingerprints and determines genetic diversity. We used genetic markers generated from selected ISSR primers to assess genetic diversity among a set of Tunisian date palm varieties. Seven primers were used to cluster 12 date palm varieties and 77 polymorphic markers were sufficient to identify all of the varieties. These discrete molecular markers were used to estimate genetic distances among the 12 accessions and to examine their genetic relationships. Data analysis identified phenetic groups that were in agreement with those obtained according to agronomic traits and random amplified polymorphic DNA (RAPD) markers. Among the 12 simple sequence repeat (SSR) motifs tested, the most abundant were AG. Key Words: Genetic diversity; ISSR polymorphisms; date palm; Pheonix dactylifera. African Journal of Biotechnology Vol. 3 (4), 2004: 215-21

Fibrome nasopharyngien

Le fibrome nasopharyngien (FNP) est une tumeur bénigne rare, richement vascularisée, touchant presque exclusivement l’adolescent de sexe masculin. Sa gravité est liée à son potentiel hémorragique et à son agressivité locale.objectif : Rappeler cette entité rare et revoir ses indications thérapeutiques.observation : Nous rapportons une observation d’un FNP avec extension au niveau de la fosse infratemporale (stade iiC de la classification de Radkowski) traité par chirurgie après embolisation ce qui a permis de diminuer le saignement peropératoire, permettant une exérèse totale de la tumeur. Les suites opératoires étaient simples. Les contrôles cliniqueet scannographique à un mois postopératoire n’ont pas montré de récidive.Conclusion : La prise en charge des FNP est essentiellement chirurgicale. elle a largement bénéficié du développement de la chirurgie endonasale et de l’artériographie interventionnelle. d’autres moyens thérapeutiques: radiothérapie, chimiothérapie, sclérothérapie et hormonothérapie ont leurs indications et leurs adeptes.Mots clés : Fibrome nasopharyngien, Chirurgie, embolisation , Chimiothérapie, Radiothérapie

Supersymmetric hybrid inflation in the braneworld scenario

In this paper we reconsider the supersymmetric hybrid inflation in the context of the braneworld scenario . The observational bounds are satisfied with an inflationary energy scale $\mu\simeq 4\times 10^{-4}M_p$, without any fine-tuning of the coupling parameter, provided that the five-dimensional Planck scale is $M_5\stackrel{<}{\sim} 2\times 10^{-3}M_p$ . We have also obtained an upper bound on the the brane tension .Comment: 8 pages (Latex