Unidirectional light emission from high-Q modes in optical microcavities

We introduce a new scheme to design optical microcavities supporting high-Q modes with unidirectional light emission. This is achieved by coupling a low-Q mode with unidirectional emission to a high-Q mode. The coupling is due to enhanced dynamical tunneling near an avoided resonance crossing. Numerical results for a microdisk with a suitably positioned air hole demonstrate the feasibility and the potential of this concept.Comment: 4 pages, 6 figures (in reduced resolution

GePEToS : A Geant4 Monte Carlo simulation package for Positron Emission Tomography

GePEToS is a simulation framework developed over the last few years for assessing the instrumental performance of future PET scanners. It is based on Geant4, written in Object-Oriented C++ and runs on Linux platforms. The validity of GePEToS has been tested on the well-known Siemens ECAT EXACT HR+ camera. The results of two application examples are presented : the design optimization of a liquid Xe micro-PET camera dedicated to small animal imaging as well as the evaluation of the effect of a strong axial magnetic field on the image resolution of a Concorde P4 micro-PET camera.Comment: 5 pages, 12 figures, submitted to IEEE Transactions on Nuclear Scienc

Optical microsphere resonators: optimal coupling to high-Q whispering gallery modes

A general model is presented for coupling of high-$Q$ whispering-gallery modes in optical microsphere resonators with coupler devices possessing discrete and continuous spectrum of propagating modes. By contrast to conventional high-Q optical cavities, in microspheres independence of high intrinsic quality-factor and controllable parameters of coupling via evanescent field offer variety of regimes earlier available in RF devices. The theory is applied to the earlier-reported data on different types of couplers to microsphere resonators and complemented by experimental demonstration of enhanced coupling efficiency (about 80%) and variable loading regimes with Q>10^8 fused silica microspheres.Comment: 14 pages, 4 figure

Experimental study of a liquid Xenon PET prototype module

A detector using liquid Xenon in the scintillation mode is studied for Positron Emission Tomography (PET). The specific design aims at taking full advantage of the liquid Xenon properties. It does feature a promising insensitive to any parallax effect. This work reports on the performances of the first LXe prototype module, equipped with a position sensitive PMT operating in the VUV range (178 nm).Comment: Proc. of the 7th International Workshops on Radiation Imaging Detectors (IWORID-7), Grenoble, France 4-7 July 200

Prevention of atherosclerosis in patients living with HIV

Ferruccio De Lorenzo1, Marta Boffito1, Sophie Collot-Teixeira2, Brian Gazzard1, John L McGregor2,3, Kevin Shotliff2, Han Xiao41General Medicine and Prevention of Vascular Disorders, Beta Cell Diabetes Centre and St Stephen’s AIDS Trust, Chelsea and Westminster Hospital NHS Foundation Trust, London, UK; 2Kings College London, Cardiovascular Division, London, UK; 3INSERM U970, PARC Hôpital Européen George Pompidou, Paris, France; 4Cardiology Department, Homerton University Hospital NHS, London, UKInvestigational product: Rosuvastatin (Crestor®; Astra Zeneca).Active ingredients: Rosuvastatin (5 mg).Study title: Prevention of Atherosclerosis in Patients Living with HIV.Phase of study: Phase III.Aims: Primary aim:• To assess whether rosuvastatin therapy could slow the progression of the carotid intima-media thickness (C-IMT; as measured by the change in the mean IMT of the near and far walls of the distal common carotid arteries) over 2 years in HIV-infected patients (HIV-IP).Secondary aims:• To assess whether rosuvastatin therapy could reduce highly sensitive C reactive protein (hs-CRP) inflammatory marker that is increased in HIV-IP.• To assess the effect of rosuvastatin therapy on serum lipid levels (total cholesterol [TC], low-density lipoprotein [LDL] cholesterol, high-density lipoprotein [HDL] cholesterol and triglycerides [TG]) and apolipoproteins (APO A1, APO B and APO B/A1).• To assess the safety of rosuvastatin in HIV-IP through the evaluation of clinical laboratory analyses (liver function tests and creatine kinase) and adverse events (AEs).Study design: Two-year randomized, double-blind, placebo-controlled, parallel group study.Planned sample size: 320 HIV-IP.Summary of eligibility criteria: HIV-IP who are aged between 30 and 60 years, with a CD4 count. greater than 200 cells/mm3. Patients must be stable on combination antiretroviral therapy (cART) for at least 12 months and have a 10-year CVD risk of less than 20% (using the Framingham risk score).Number of study centers: One.Duration of treatment: Two years (5 mg rosuvastatin or placebo once daily).Dose and route of administration: Oral rosuvastatin (5 mg) once daily.The incidence of cardiovascular disease (CVD) in HIV-IP is at least three times higher than in the general population and further increases each year with combination anti-retroviral therapy (cART). The carotid atherosclerosis progression rate is 10 times higher in HIV-IP than in uninfected individuals. The aim of this study is to assess whether therapy with 5 mg rosuvastatin could:1) Slow the progression in the mean IMT of the distal common carotid arteries over two years in HIV-IP.2) Change the concentration in the inflammatory marker – hs-CRP, which is increased in HIV-IP.3) Change the concentrations of TC, LDL cholesterol, HDL cholesterol, TG, apolipoproteins (APO) B, APO A1 and APO B/A1.4) Be administered safely in the study population.Pharmacological intervention with rosuvastatin will be evaluated in a double-blind, placebo-controlled, randomized clinical trial in HIV-IP treated with cART not matching the published selection criteria for lipid-lowering therapy. For the first time, this study will investigate anti-inflammatory and anti-atherogenic effects of a pharmacological lipid-lowering agent in HIV-IP that may lead to the reduction of CVD.Keywords: rosuvastatin, atherosclerosis, cardiovascular disease, HIV, clinical trial protoco

A liquid Xenon Positron Emission Tomograph for small animal imaging : first experimental results of a prototype cell

A detector using liquid Xenon (LXe) in the scintillation mode is studied for Positron Emission Tomography (PET) of small animals. Its specific design aims at taking full advantage of the Liquid Xenon scintillation properties. This paper reports on energy, time and spatial resolution capabilities of the first LXe prototype module equipped with a Position Sensitive Photo- Multiplier tube (PSPMT) operating in the VUV range (178 nm) and at 165 K. The experimental results show that such a LXe PET configuration might be a promising solution insensitive to any parallax effect.Comment: 34 pages, 18 pages, to appear in NIM

34. HIGH-RESOLUTION ELECTRICAL IMAGING IN THE NEW HEBRIDES ISLAND ARC: STRUCTURAL ANALYSIS AND STRESS STUDIES

ABSTRACT Electrical images recorded with the Formation MicroScanner in three of seven holes drilled during Leg 134 were analyzed to study the effect of the collision of the d'Entrecasteaux Ridge with the central New Hebrides Island Arc. Structural features such as bedding, faults, fractures, folds, and shear zones, automatically detected and interactively mapped from the images, were interpreted to document the deformation processes caused by the collision. At Site 829 the images show the imbricated structure of the thrust sheets in the accretionary complex. At Sites 832 and 833 the structural features observed and the compressional-stress information inferred from breakout analyses and hydraulic fractures indicate that the intra-arc North Aoba Basin is still subject to a east-northeast-west-southwest compression. This compression, which is associated with the uplift of the eastern part of the basin, is not older than latest Pliocene

Mode structure and ray dynamics of a parabolic dome microcavity

We consider the wave and ray dynamics of the electromagnetic field in a parabolic dome microcavity. The structure of the fundamental s-wave involves a main lobe in which the electromagnetic field is confined around the focal point in an effective volume of the order of a cubic wavelength, while the modes with finite angular momentum have a structure that avoids the focal area and have correspondingly larger effective volume. The ray dynamics indicates that the fundamental s-wave is robust with respect to small geometrical deformations of the cavity, while the higher order modes are associated with ray chaos and short-lived. We discuss the incidence of these results on the modification of the spontaneous emission dynamics of an emitter placed in such a parabolic dome microcavity.Comment: 50 pages, 17 figure

Evidence for sinistral strike-slip deformation in the Solomon Island arc

6 pages, 4 figuresDuring the SOPACMAPS 2 crusie carried out by IFREMER (Institut Français de Recherche pour l'Exploitation de la Mer) and ORSTOM (Institut Français de Recherche Scientifique pour le dévelopement en Coopération) on theR/V L'Atalante, in the Central Solomon Arc area, multibeam bathymetric and imagery data and single-channel seismic reflection profiles were collected from an area of about 3500 km2, to evaluate regional tectonics. Structural data geophysical profiles interpretation provide evidence for left-lateral transtensional tectonics on the southern edge of the Central Solomon Trough. This transtensional deformation is represented by faulting, block tilting, and rhombohedral deformation. The regional geology and the analysis of the sedimentary cover allow us to demonstrate that this tectonic occurred in two different phases during Oligocene to Miocene and Pliocene to Pleistocene timesPeer reviewe