55 research outputs found
Frequency parametrization to numerically predict flutter in turbomachinery
In the quest for performance, modern turbomachinery designs are increasingly
proner to flutter hazards. Unfortunately, their prediction is currently too expensive and
inaccurate for industrial purpose. A significant step towards faster methods would consist
in substituting a sequential algorithm to the classical iterative ones encountered in loose
coupling strategies. The approach proposed here makes it possible through the use of
a meta-model taking into account the sensitivity to design variables. This parametrized
method is evaluated on a standard well referenced turbine configuration
Nasal Carriage of Staphylococcus Aureus and Cross-Contamination in a Surgical Intensive Care Unit: Efficacy of Mupirocin Ointment
A six month prospective study was carried out in a surgical intensive care unit (SICU) of a university hospital to assess the incidence and routes of exogenous colonization by Staphylococcus aureus. A total of 157 patients were included in the study. One thousand one hundred and eleven specimens (nasal, surgical wound swabs, tracheal secretions obtained on admission and once a week thereafter, and all clinical specimens) were collected over a four month period from patients without nasal decontamination (A). They were compared with 729 specimens collected over a two month period from patients treated with nasal mupirocin ointment (B). All S. aureus strains were typed by restriction fragment length polymorphism (RFLP) pulsed-field gel electrophoresis after SmaI macrorestriction. The nasal colonization rates on admission were 25.5 and 32.7% in groups A and B, respectively. Thirty-one untreated patients (31.3%) and three patients (5.1%) treated with nasal ointment, acquired the nasal S. aureus in the SICU (P = 0.00027). Nasal carriers were more frequently colonized in the bronchopulmonary tract (Bp) and surgical wound (Sw) (62%) than patients who were not nasal carriers (14%) (P < 0.00001). The patterns were identical for nasal, Bp and Sw strains from the same patient. RFLP analysis characterized seven epidemic strains of methicillin-resistant S. aureus (MRSA) which colonized 60% of group A and 9% of group B patients (P < 0.00001). The bronchopulmonary tract infection rate was reduced in group B (P = 0.032). In conclusion, in an SICU, nasal carriage of S. aureus appeared to be the source of endogenous and cross- colonization. The use of nasal mupirocin ointment reduced the incidence of Bp and Sw colonization, as well as the MRSA infection rate
Experimental and Numerical Investigations of a Dual-Shaft Test Rig with Intershaft Bearing
This paper deals with an experimental study of a dual rotor test rig. This
machine, which was developed and built at the Laboratoire de
Tribologie et Dynamique des Systèmes, Ecole Centrale de Lyon, will
be first presented. It is composed of two coaxial shafts that are connected by
an intershaft bearing and rotate independently, each one driven by its own
motor. Their lateral vibrations and whirling motion are coupled by the intershaft
bearing. The experimental tests consisting in run-ups and the associated
measured unbalance response of the dual rotor will be investigated. The
influence of the rotation of each rotor on the critical speeds and the associated
amplitudes will be discussed. Moreover, this paper presents a numerical model
of the dual rotor. Correlations between the experimental and numerical tests will
be investigated. The objective is to be able to predict phenomena observed in
experiments, starting from a rather fine numerical model
Microbiological and epidemiological features of clinical respiratory isolates of Burkholderia gladioli
The role of water fittings in intensive care rooms as reservoirs for the colonization of patients with Pseudomonas aeruginosa
International audienceOBJECTIVE: To assess the role of the water environment in the Pseudomonas aeruginosa colonization of patients in intensive care units in the absence of a recognized outbreak. DESIGN AND SETTING: Prospective, single-centre study over an 8-week period in two adult ICUs at a university hospital. Environmental samples were taken from the water fittings of rooms once per week, during a 8-week period. Patients were screened weekly for P. aeruginosa carriage. Environmental and humans isolates were genotyped by using pulsed-field gel electrophoresis. RESULTS: P. aeruginosa was detected in 193 (86.2%) of the 224 U-bend samples and 10 of the 224 samples taken from the tap (4.5%). Seventeen of the 123 patients admitted were colonized with P. aeruginosa. Only one of the 14 patients we were able to evaluate was colonized by a clone present in the water environment of his room before the patient's first positive sample was obtained. CONCLUSION: The role of the water environment in the acquisition of P. aeruginosa by intensive care patients remains unclear, but water fittings seem to play a smaller role in non-epidemic situations than expected by many operational hospital hygiene teams
Risk Factors for Colonization with Extended-Spectrum β-Lactamase–producing Bacteria and Intensive Care Unit Admission
Coexisting conditions and previous antimicrobial drug exposure predict colonization
Evidence for Induction of Integron-Based Antibiotic Resistance by the SOS Response in a Clinical Setting
Bacterial resistance to β-lactams may rely on acquired β-lactamases encoded by class 1 integron-borne genes. Rearrangement of integron cassette arrays is mediated by the integrase IntI1. It has been previously established that integrase expression can be activated by the SOS response in vitro, leading to speculation that this is an important clinical mechanism of acquiring resistance. Here we report the first in vivo evidence of the impact of SOS response activated by the antibiotic treatment given to a patient and its output in terms of resistance development. We identified a new mechanism of modulation of antibiotic resistance in integrons, based on the insertion of a genetic element, the gcuF1 cassette, upstream of the integron-borne cassette blaOXA-28 encoding an extended spectrum β-lactamase. This insertion creates the fused protein GCUF1-OXA-28 and modulates the transcription, the translation, and the secretion of the β-lactamase in a Pseudomonas aeruginosa isolate (S-Pae) susceptible to the third generation cephalosporin ceftazidime. We found that the metronidazole, not an anti-pseudomonal antibiotic given to the first patient infected with S-Pae, triggered the SOS response that subsequently activated the integrase IntI1 expression. This resulted in the rearrangement of the integron gene cassette array, through excision of the gcuF1 cassette, and the full expression the β-lactamase in an isolate (R-Pae) highly resistant to ceftazidime, which further spread to other patients within our hospital. Our results demonstrate that in human hosts, the antibiotic-induced SOS response in pathogens could play a pivotal role in adaptation process of the bacteria
Limits of patient isolation measures to control extended-spectrum beta-lactamase–producing Enterobacteriaceae: model-based analysis of clinical data in a pediatric ward
Infectious diseases in allogeneic haematopoietic stem cell transplantation: prevention and prophylaxis strategy guidelines 2016
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