Partial cricotracheal resection for pediatric subglottic stenosis: a single institution's experience in 60 cases

Abstract.: In our study, 60 infants and children, each with a severe subglottic stenosis (SGS), underwent partial cricotracheal resection (PCTR) with primary thyrotracheal anastomosis. According to the Myer-Cotton classification, two were grade II, 41 were grade III and 17 were grade IV stenoses. Of the 60 patients, 57 (95%) are presently decannulated, and one patient sustained a complete restenosis. Two patients with better than 80% subglottic airways still are waiting for decannulation: one because of bilateral cricoarytenoid joint fixation and the second because of temporary stenting of the subglottis with a Montgomery T-tube. The rate of decannulation is 97% (36 of 37 cases) in primary PCTRs, 100% (13 of 13 cases) in salvage PCTRs for failed laryngotracheal reconstructions (LTR) and 70% (7 of 10 cases) in extended PCTRs (i.e., PCTR associated with an additional open-airway procedure

Definitive Evidence for Order-by-Quantum-Disorder in Er2Ti2O7

Here we establish the systematic existence of a U(1) degeneracy of all symmetry-allowed Hamiltonians quadratic in the spins on the pyrochlore lattice, at the mean-field level. By extracting the Hamiltonian of Er2Ti2O7 from inelastic neutron scattering measurements, we then show that the U(1)-degenerate states of Er2Ti2O7 are its classical ground states, and unambiguously show that quantum fluctuations break the degeneracy in a way which is confirmed by experiment. This is the first definitive observation of order-by-disorder in any material. We provide further verifiable consequences of this phenomenon, and several additional comparisons between theory and experiment.Comment: 4.5 pages, 3 figures, 7.5 pages of Supplemental Material, 8 supplemental figure

Simultaneous Determination of Human Plasma Levels of Citalopram, Paroxetine, Sertraline, and Their Metabolites by Gas Chromatography—Mass Spectrometry

A gas chromatography—mass spectrometry method is presented which allows the simultaneous determination of the plasma concentrations of the selective serotonin reuptake inhibitors citalopram, paroxetine, sertraline, and their pharmacologically active N-demethylated metabolites (desmethylcitalopram, didesmethylcitalopram, and desmethylsertraline) after derivatization with the reagent N-methyl-bis(trifluoroacetamide). No interferences from endogenous compounds are observed following the extraction of plasma samples from six different human subjects. The standard curves are linear over a working range of 10-500 ng/mL for citalopram, 10-300 ng/mL for desmethylcitalopram, 5-60 ng/mL for didesmethylcitalopram, 20-400 ng/mL for sertraline and desmethylsertraline, and 10-200 ng/mL for paroxetine. Recoveries measured at three concentrations range from 81 to 118% for the tertiary amines (citalopram and the internal standard methylmaprotiline), 73 to 95% for the secondary amines (desmethylcitalopram, paroxetine and sertraline), and 39 to 66% for the primary amines (didesmethylcitalopram and desmethylsertraline). Intra- and interday coefficients of variation determined at three concentrations range from 3 to 11 % for citalopram and its metabolites, 4 to 15% for paroxetine, and 5 to 13% for sertraline and desmethylsertraline. The limits of quantitation of the method are 2 ng/mL for citalopram and paroxetine, 1 ng/mL for sertraline, and 0.5 ng/mL for desmethylcitalopram, didesmethylcitalopram, and desmethylsertraline. No interferences are noted from 20 other psychotropic drugs. This sensitive and specific method can be used for single-dose pharmacokinetics. It is also useful for therapeutic drug monitoring of these three drugs and could possibly be adapted for the quantitation of the two other selective serotonin reuptake inhibitors on the market, namely fluoxetine and fluvoxamin

Modélisation de l'évolution du couvert nival, sur le sous-bassin LG4 de la rivière La Grande dans le nord du Québec, à l'aide du modèle français CROCUS

Au Québec, l'accumulation de la neige au sol prend une grande importance dans bon nombre d'activités humaines comme la production d'hydroélectricité. Face à cette importance de la neige, il devient fort intéressant de faire appel à des outils de modélisation dans le but de faire le suivi complet du manteau neigeux par la simulation des différents processus physiques agissant sur le couvert nival. En ce sens, la présente recherche vise à évaluer la capacité d'adaptation aux conditions environnementales du Québec, du modèle français multicouches CROCUS de suivi et de fonte du couvert nival, en vue de son utilisation ultérieure. Le choix du site d'étude s'accorde avec la présence de stations d'acquisition de données sur le couvert nival et la disponibilité d'un large éventail de données météorologiques essentielles aux modélisations.Suite au prétraitement des données d'entrée, le modèle CROCUS a pu être étalonné dans le but d'évaluer ses aptitudes à simuler l'évolution de l'épaisseur et de l'équivalent en eau du couvert nival, de même que les profils de densité et de température de ce couvert. Compte tenu des données disponibles, les résultats des périodes d'étalonnage et de vérification peuvent être considérés comme très bons et très encourageants pour des applications ultérieures de CROCUS au Québec.In Québec, snow accumulation on the ground is important for a large number of activities, including hydroelectric production. Snow being an important environmental aspect to look at for operations in cold regions, making use of adequate models able to simulate the various physical processes affecting the characteristics of the snowpack throughout the entire snow season becomes also quite important. So, the present project aims to evaluate the ability of the CROCUS French multilayer snow model to be adapted to Northern Quebec environmental conditions. The choice of the study area has been done on the basis of data availability on both the temporal evolution the snowpack at three automatic stations and the meteorological variables necessary as input to the model. Following preprocessing of input data, the CROCUS model has been calibrated in order to evaluate his capability to simulate the temporal evolution not only of the thickness and water equivalent of the snowpack, but also of the density and temperature profiles within the pack. Given the available data, the results for both the calibration and verification periods can be considered as good and very encouraging for future applications of the CROCUS model in Québec

LHC Superconducting Dipole Production Follow-up: Results of Audit on QA Aspects in Industry

The manufacturing of the 1232 Superconducting Main Dipoles for LHC is under way at three European Contractors: Alstom-Jeumont (Consortium), Ansaldo Superconduttori Genova and Babcock Noell Nuclear. The manufacturing is proceeding in a very satisfactory way and in March 2005 the mid production was achieved. To intercept eventually âﾜweak pointsâ of the production process still present and in order to make a check of the Quality Assurance and Control in place for the series production, an Audit action was launched by CERN during summer-fall 2004. Aspects like: completion of Production and Quality Assurance documentation, structure of QC Teams, traceability, calibration and maintenance for tooling, incoming components inspections, were checked during a total of seven visits at the five different production sites. The results of the Audit in terms of analysis of âﾜsystematicâ and âﾜrandomâ problems encountered as well as corrective actions requested are presented

Quality Control Techniques Applied to the Large Scale Production of Superconducting Dipole Magnets for LHC

The LHC accelerator, under construction at CERN, is characterized by the use on a large scale of high field superconducting dipoles: the 27-km ring requires 1232 15-m long dipole magnets designed for a peak field of 9 T. The coils are wound with Rutherford-type cable based on copper-stabilized Nb-Ti superconductors and will be operated at 1.9 K in pressurized superfluid helium. The challenge that had to be faced has been an efficient, cost-effective and reproducible mass production to very tight tolerances: the field quality must be better than 10-4 and the geometry of the cold bore tube and magnet controlled to 0.1 mm over the whole length, any deviation being liable to induce delays and significant cost increase. This paper presents the main methods and tools chosen to face successfully this challenge: some methods were foreseen in the technical specification, others were implemented based on the experience gained in several years of fabrication

Performance of the LHC Final Prototype and First Pre-series Superconducting Dipole Magnets

Within the LHC cryo-dipole program, six full-scale superconducting prototypes of final design were built in collaboration between Industry and CERN, followed by launching the manufacture of pre-series magnets. Five prototypes and the first of the pre-series magnets were tested at CERN. This paper reviews the main features and the performance of the cryo-dipoles tested at 4.2 K and 1.8 K. The results of the quench training, conductor performance, magnet protection, sensitivity to ramp rate and field characteristics are presented and discussed in terms of the design parameters

The Quality Control of the LHC Continuous Cryostat Interconnections

The interconnections between the Large Hadron Collider (LHC) magnets have required some 40 000 TIG welded joints and 65 000 electrical splices. At the level of single joints and splices, non-destructive techniques find limited application: quality control is based on the qualification of the process and of operators, on the recording of production parameters and on production samples. Visual inspection and process audits were the main techniques used. At the level of an extended chain of joints and splices - from a 53.5 m half-cell to a complete 2.7 km arc sector - quality control is based on vacuum leak tests, electrical tests and RF microwave reflectometry that progressively validated the work performed. Subsequent pressure tests, cryogenic circuits flushing with high pressure helium and cool-downs revealed a few unseen or new defects. This paper presents an overview of the quality control techniques used, seeking lessons applicable to similar large, complex projects

Final Prototypes, First Pre-series Units and Steps Towards Series Production of the LHC Main Dipoles

The LHC, a 7 TeV proton collider presently under construction at CERN, requires 1232 superconducting dipole magnets, featuring a nominal field of 8.33 T inside a cold bore tube of 50 mm inner diameter and a magnetic length of 14.3 m. This paper summarises the results of the program of the six LHC main dipole final prototypes and presents the performance measurements of the first magnets of the 90 pre-series units currently under manufacture by industry. Results of geometric and magnetic measurements are given and discussed. Finally, the major milestones towards the dipole magnets series manufacture are given and commented

Electrical Integrity Tests during Production of the LHC Dipoles

For the LHC dipoles, mandatory electrical integrity tests are performed to qualify the cold mass (CM) at four production stages: individual pole, collared coil, CM before end cover welding and final CM. A description of the measurement equipment and its recent development are presented. After passing the demands set out in the specification, the results of the tests are transmitted to CERN where they are further analyzed. The paper presents the most important results of these measurements. We also report a review of the electrical non-conformities encountered e.g. interturn shorts and quench heater failure, their diagnostic and the cures