Accretion disc outbursts: a new version of an old model

We have developed 1D time-dependent numerical models of accretion discs, using an adaptive grid technique and an implicit numerical scheme, in which the disc size is allowed to vary with time. The code fully resolves the cooling and heating fronts propagating in the disc. We show that models in which the radius of the outer edge of the disc is fixed produce incorrect results, from which probably incorrect conclusions about the viscosity law have been inferred. In particular we show that outside-in outbursts are possible when a standard bimodal behaviour of the Shakura-Sunyaev viscosity parameter alpha is used. We also discuss to what extent insufficient grid resolutions have limited the predictive power of previous models. We find that the global properties (magnitudes, etc. ...) of transient discs can be addressed by codes using a high, but reasonable, number of fixed grid points. However, the study of the detailed physical properties of the transition fronts generally requires resolutions which are out of reach of fixed grid codes. It appears that most time-dependent models of accretion discs published in the literature have been limited by resolution effects, improper outer boundary conditions, or both.Comment: 13 pages, 12 figures; accepted for publication in MNRA

Identification of a 7-phase claw-pole starter-alternator for a micro-hybrid automotive application

This paper deals with the identification of a new high power starter-alternator system, using both: a Finite Element Method (FEM) modeling and an experimental vector control. The drive is composed of a synchronous 7-phase claw-pole machine supplied with a low voltage / high current Voltage Source Inverter (VSI). This structure needs specific approaches to plan its electrical and mechanical behaviors and to identify the parameters needed for control purpose. At first, a Finite Element Method (FEM) modeling of the machine is presented. It is used for the predetermination of the electromotive forces and of the torque. Experimental results are in good accordance with numerical results. In a second part, resistive and inductive parameters of the drive are determined by an original experimental approach that takes into account each component of the drive: the battery, the VSI and the machine.Futurelec IV (Region Nord Pas de Calais

Modeling and Control of a 7-phase Claw-pole Starter-alternator for a Micro-hybrid Automotive Application

This paper deals with the modeling and the control of a new high power 12V Integrated Starter Alternator (ISA). This system is used to bring micro-hybrid functions to standard Internal Combustion Engine (ICE) vehicles. The drive is composed of a seven-phase synchronous claw-pole machine with separate excitation, supplied with a seven-leg Voltage Source Inverter (VSI) designed for low voltage and high current. The system is modeled in a generalized Concordia frame and a graphical description is used to highlight energetic properties of such a complex system. A control scheme is then deduced from this graphical description. Two controls are achieved in generator mode and compared: one is using the VSI in a square-wave mode, the other in a Pulse Width Modulation (PWM) mode. Experimental results are provided.This work was supported by the French car supplier Valeoand the regional council of France Region-Nord-Pas-De-Calais

Design and Experimental Investigation of a Hybrid Rotor Permanent Magnet Modular Machine with 3D Flux Paths Accounting for Recyclability of Permanent Magnet Material

Rare-earth metals used for manufacturing Permanent Magnets (PMs) remain classified as critical raw materials by the European Commission. In order to secure the supply of electrical machines due to the increasing demand of Hybrid and Full Electrical Vehicles ((H)EVs), recycling has emerged as a valuable alternative. Hence, this paper presents the concept of a modular PM machine with a hybrid rotor and 3D flux paths, for application in ((H)EVs). The proposed machine topology is intended to facilitate the extraction of PM material towards a recycling process. The selection of a machine for prototyping is carried out by investigating the effect of the variation of the number of rotor teeth and stator modules on various parameters, with models developed in Finite Element (FE). Finally, the models developed of the selected combination were validated with a detailed experimental evaluation of the prototype

Outbreak of Corynebacterium pseudodiphtheriticum Infection in Cystic Fibrosis Patients, France

Respiratory tract colonization with these bacteria may be common in this population

Genomic analysis of an emerging multiresistant Staphylococcus aureus strain rapidly spreading in cystic fibrosis patients revealed the presence of an antibiotic inducible bacteriophage

BACKGROUND: Staphylococcus aureus is a major human pathogen responsible for a variety of nosocomial and community-acquired infections. Recent reports show that the prevalence of Methicillin-Resistant S. aureus (MRSA) infections in cystic fibrosis (CF) patients is increasing. In 2006 in Marseille, France, we have detected an atypical MRSA strain with a specific antibiotic susceptibility profile and a unique growth phenotype. Because of the clinical importance of the spread of such strain among CF patients we decided to sequence the genome of one representative isolate (strain CF-Marseille) to compare this to the published genome sequences. We also conducted a retrospective epidemiological analysis on all S. aureus isolated from 2002 to 2007 in CF patients from our institution. RESULTS: CF-Marseille is multidrug resistant, has a hetero-Glycopeptide-Intermediate resistance S. aureus phenotype, grows on Cepacia agar with intense orange pigmentation and has a thickened cell wall. Phylogenetic analyses using Complete Genome Hybridization and Multi Locus VNTR Assay showed that CF-Marseille was closely related to strain Mu50, representing vancomycin-resistant S. aureus. Analysis of CF-Marseille shows a similar core genome to that of previously sequenced MRSA strains but with a different genomic organization due to the presence of specific mobile genetic elements i.e. a new SCCmec type IV mosaic cassette that has integrated the pUB110 plasmid, and a new phage closely related to phiETA3. Moreover this phage could be seen by electron microscopy when mobilized with several antibiotics commonly used in CF patients including, tobramycin, ciprofloxacin, cotrimoxazole, or imipenem. Phylogenetic analysis of phenotypically similar h-GISA in our study also suggests that CF patients are colonized by polyclonal populations of MRSA that represents an incredible reservoir for lateral gene transfer. CONCLUSION: In conclusion, we demonstrated the emergence and spreading of a new isolate of MRSA in CF patients in Marseille, France, that has probably been selected in the airways by antibiotic pressure. Antibiotic-mediated phage induction may result in high-frequency transfer and the unintended consequence of promoting the spread of virulence and/or antibiotic resistance determinants. The emergence of well-adapted MRSA is worrying in such population chronically colonized and receiving many antibiotics and represents a model for emergence of uncontrollable super bugs in a specific niche. REVIEWERS: This article was reviewed by Eric Bapteste, Pierre Pontarotti, and Igor Zhulin. For the full reviews, please go to the Reviewers' comments section

Inquilinus limosus and Cystic Fibrosis

International audienc

Mycobacterium chimaera pulmonary infection complicating cystic fibrosis: a case report

<p>Abstract</p> <p>Background</p> <p><it>Mycobacterium chimaera </it>is a recently described species within the <it>Mycobacterium avium </it>complex. Its pathogenicity in respiratory tract infection remains disputed. It has never been isolated during cystic fibrosis respiratory tract infection.</p> <p>Case presentation</p> <p>An 11-year-old boy of Asian ethnicity who was born on Réunion Island presented to our hospital with cystic fibrosis after a decline in his respiratory function over the course of seven years. We found that the decline in his respiratory function was correlated with the persistent presence of a <it>Mycobacterium avium </it>complex organism further identified as <it>M. chimaera</it>.</p> <p>Conclusion</p> <p>Using sequencing-based methods of identification, we observed that <it>M. chimaera </it>organisms contributed equally to respiratory tract infections in patients with cystic fibrosis when compared with <it>M. avium </it>subsp. <it>hominissuis </it>isolates. We believe that <it>M. chimaera </it>should be regarded as an emerging opportunistic respiratory pathogen in patients with cystic fibrosis, including young children, and that its detection warrants long-lasting appropriate anti-mycobacterial treatment to eradicate it.</p

First isolation of two colistin-resistant emerging pathogens, Brevundimonas diminuta and Ochrobactrum anthropi, in a woman with cystic fibrosis: a case report

<p>Abstract</p> <p>Introduction</p> <p>Cystic fibrosis afflicted lungs support the growth of many bacteria rarely implicated in other cases of human infections.</p> <p>Case presentation</p> <p>We report the isolation and identification, by 16S rRNA amplification and sequencing, of two emerging pathogens resistant to colistin, <it>Brevundimonas diminuta </it>and <it>Ochrobactrum anthropi</it>, in a 17-year-old woman with cystic fibrosis and pneumonia. The patient eventually responded well to a 2-week regime of imipenem and tobramycin.</p> <p>Conclusion</p> <p>Our results clearly re-emphasize the emergence of new colistin-resistant pathogens in patients with cystic fibrosis.</p

Nocardia farcinica lung infection in a patient with cystic fibrosis: a case report

<p>Abstract</p> <p>Introduction</p> <p>Respiratory tract infections are the major causes of morbidity and mortality in patients with cystic fibrosis. <it>Nocardia </it>are rarely implicated in these infections and few reports of the involvement of this species are found in the literature.</p> <p>Case presentation</p> <p>We describe a case of lung infection followed by chronic colonization of trimethoprim and sulfamethoxazole resistant <it>Nocardia farcinica </it>in a patient with cystic fibrosis. The chronic colonization of this uncommon bacterium in patients with cystic fibrosis was proved using a newly developed real-time polymerase chain reaction assay, which indicates that this bacterium, despite treatment, is difficult to eradicate.</p> <p>Conclusion</p> <p>Our case report confirms that this organism can be recovered in persons with cystic fibrosis. Its eradication is necessary especially if the patient is to undergo lung transplantation.</p