Photon-avalanche upconversion of red light into blue light in a thulium-doped fluorozirconate fibre

We report the investigation of the photon-avalanche effect in heavily thulium-doped fluorozirconate fibre. Pumping at red wavelengths, which are not resonant with the ground-state absorption, gives blue emission at 450nm and 480nm

Blue avalanche upconversion in Tm:ZBLAN fibre

We report the investigation of the photon avalanche effect in heavily doped Tm:ZBLAN fibre at room temperature. Pumping at 630nm to 650nm, which is not resonant with the ground state absorption, gives intense blue emissions at 450nm and 480nm. The time evolution of the absorption and emission show a slow decaying oscillation before steady state is reached

Consistency checks of results from a Monte Carlo code intercomparison for emitted electron spectra and energy deposition around a single gold nanoparticle irradiated by X-rays

Organized by the European Radiation Dosimetry Group (EURADOS), a Monte Carlo code intercomparison exercise was conducted where participants simulated the emitted electron spectra and energy deposition around a single gold nanoparticle (GNP) irradiated by X-rays. In the exercise, the participants scored energy imparted in concentric spherical shells around a spherical volume filled with gold or water as well as the spectral distribution of electrons leaving the GNP. Initially, only the ratio of energy deposition with and without GNP was to be reported. During the evaluation of the exercise, however, the data for energy deposition in the presence and absence of the GNP were also requested. A GNP size of 50 nm and 100 nm diameter was considered as well as two different X-ray spectra (50 kVp and 100 kVp). This introduced a redundancy that can be used to cross-validate the internal consistency of the simulation results. In this work, evaluation of the reported results is presented in terms of integral quantities that can be benchmarked against values obtained from physical properties of the radiation spectra and materials involved. The impact of different interaction cross-section datasets and their implementation in the different Monte Carlo codes is also discussed

Individual and environmental determinants associated with longer times to access pediatric rheumatology centers for patients with juvenile idiopathic arthritis, a JIR cohort study.

Despite guidelines, poor access to appropriate care for juvenile idiopathic arthritis (JIA) patients remains a global issue. Prompt referral to a pediatric rheumatology (PR) center and effective care is known to be critical for changing the natural history of the disease and improving long-term prognosis. This project assesses socio-economic factors of delayed referral to a pediatric rheumatologist (PRst) for JIA patients in France and Switzerland within the Juvenile Inflammatory Rheumatism (JIR) Cohort. All patients diagnosed with JIA, presenting at one center of the JIRcohort in France or Switzerland with additional data on referral pathway were included. Patient characteristics at first visit to the PR center, dates of visits to healthcare providers during referral, and parent characteristics were extracted from the JIRcohort database. Two hundred fifty children were included. The overall median time to first PR assessment was 2.4 months [1.3; 6.9] and ranged widely across the JIA subtypes, from 1.4 months [0.6; 3.8] for children with systemic juvenile idiopathic arthritis (sJIA) to 5.3 months [2.0; 19.1] for children with enthesitis-related arthritis (ERA). A diagnosis of ERA and an appointment with an orthopedist during the referral pathway were significantly associated with a longer time before the first PR visit (hazard ratio HR 0.50 [95% CI: 0.29; 0.84]) and HR 0.68 [95% CI: 0.49; 0.93], respectively) in multivariable analysis. Having a mother with a post-graduate educational attainment level was tendentially associated with a shorter time before the first PR visit, (HR 1.32 [95% CI: 0.99; 1.78]). Time to first PRst visit was most often short compared to other studies and close to the British recommendations. However, this time remained too long for many patients. We observed no social inequities in access to a PRst, but we show the need to improve effective pathway and access to a PR center for JIA patients

Photon avalanche upconversion in heavily thulium-doped ZBLAN fibre

Photon avalanche mechanism results from a cross relaxation energy transfer induced build up of population in an intermediate metastable level without resonant Ground State Absorption (GSA). From this level a resonant absorption occurs to populate a higher level The main characteristics of such process is a power threshold which corresponds to a sudden increase of the fluorescence arising from the upper excited state as well as a slowing and a change of the rise shape of the transient signals

Echocardiographie chez le footballeur professionnel : comparaison entre les décennies 1980 et 2000

Etude de la morphologie cardiaque chez des footballeurs d'élite suivant un entraînement moderne sollicitant les métabolismes aérobie et anaérobie et soumis à un rythme intense de compétition; comparaison avec les résultats recueillis chez des joueurs de même niveau 20 ans auparavant

Design of Grating-Based Fiber Lasers : Power and Spectral Behaviors

The spectral and power characteristics of Nd$^{3+}$ doped silica-based fiber lasers utilizing two intracore Bragg grating reflectors have been investigated. The operation of low-threshold, high efficiency Nd$^{3+}$ doped fiber lasers are reported. The frequency of these lasers can be tuned to resonance with several absorption lines of atomic or molecular species. Coupled cavity effects have been used to reduce the linewidth of the laser emission and to carry out a single model Nd$^{3+}$ fiber laser. The influence of the medium birefringence on the laser emission in a low and in a Hi-Bi fiber is presented. Recently, a new photorefractive effect occurring in cerium doped fluorozirconate fibers has been demonstrated in our laboratories. To demonstrate the potentiality of Bragg gratings to fluorozirconate fiber technology, a fiber laser using a Bragg reflector written in a Ce-Er codoped ZBLALi fiber is reported

Rare Earth Doped Fluoride Fibre Lasers Using Direct-Coated Dielectric Mirrors

In this letter, we report on the realisation of fluoride fibre lasers. Mirrors were directly deposited on fibre endfaces. Using this technique, we have fabricated stable fibre lasers. Then, we present our recent results on fluoride fibre lasers