High resolution cw laser beam preamplified in a multipass cavity pumped by a CuHBr (HyBrID) laser

International audienceThe amplification of a cw high resolution (1 MHz) single-mode dye laser in a single-stage, multipass preamplifier based on a free flowing dye jet as amplifying medium is reported. The device is pumped by a homemade CuHBr laser (HyBrID laser) (18 kHz repetition rate, 30 ns pulse duration at half-maximum and 80 ns at its base) and yields pulses of duration of 10 ns (at half-maximum). In the studied pump energy domain, the gain is a linear function of pump energy and the maximum value obtained so far with pump energy of 400 μJ is 25 μJ per pulse for an input beam power of 30 mW. The corresponding gain is of the order of 10 4. We assume that a higher gain can be reached using better quality elements. The output beam is a high quality TM 00 mode. The pulse shapes of the pump beam and the output beam are compared and a phenomenological model ("switched photon lifetime") is introduced that reproduces our observations with a good agreement

Refined Orientation of the Optical Axes as a Function of Wavelength in Monoclinic Double Tungstates

We measured the rotation of the dielectric frame and determined the orientation of the optical axes in KRE(WO4)2 (RE = Gd, Y, Lu) crystals, as a function of wavelength in the 0.4-1.6 μm range

Burkholderia anthina sp. nov. and Burkholderia pyrrocinia , two additional Burkholderia cepacia complex bacteria, may confound results of new molecular diagnostic tools

Nineteen Burkholderia cepacia -like isolates of human and environmental origin could not be assigned to one of the seven currently established genomovars using recently developed molecular diagnostic tools for B. cepacia complex bacteria. Various genotypic and phenotypic characteristics were examined. The results of this polyphasic study allowed classification of the 19 isolates as an eighth B. cepacia complex genomovar ( Burkholderia anthina sp. nov.) and to design tools for its identification in the diagnostic laboratory. In addition, new and published data for Burkholderia pyrrocinia indicated that this soil bacterium is also a member of the B. cepacia complex. This highlights another potential source for diagnostic problems with B. cepacia -like bacteria.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/71564/1/j.1574-695X.2002.tb00584.x.pd

Epidemiology of Burkholderia cepacia Complex in Patients with Cystic Fibrosis, Canada

The Burkholderia cepacia complex is an important group of pathogens in patients with cystic fibrosis (CF). Although evidence for patient-to-patient spread is clear, microbial factors facilitating transmission are poorly understood. To identify microbial clones with enhanced transmissibility, we evaluated B. cepacia complex isolates from patients with CF from throughout Canada. A total of 905 isolates from the B. cepacia complex were recovered from 447 patients in 8 of the 10 provinces; 369 (83%) of these patients had genomovar III and 43 (9.6%) had B. multivorans (genomovar II). Infection prevalence differed substantially by region (22% of patients in Ontario vs. 5% in Quebec). Results of typing by random amplified polymorphic DNA analysis or pulsed-field gel electrophoresis indicated that strains of B. cepacia complex from genomovar III are the most potentially transmissible and that the B. cepacia epidemic strain marker is a robust marker for transmissibility

Decrease in antibiotic resistance among invasive pneumococcal disease (IPD) isolates in France from 2003 to 2007; On-going survey of the French Pneumococcus network (ORP)

Date du colloque&nbsp;: 10/2008</p

Epidemiology and Antimicrobial Resistance of Streptococcus pneumoniae in France in 2007: Data from the Pneumococcus Surveillance Network

Antimicrobial resistance of Streptococcus pneumoniae in France is closely monitored by the pneumococcus surveillance network, founded in 1995, which collects data from regional observatories (Observatoire Régionaux du Pneumocoque [ORP]). In 2007, 23 ORPs analyzed the antibiotic susceptibility of 5,302 isolates of S. pneumoniae recovered in France from cerebrospinal fluid, blood, middle ear fluid, and pleural fluid, as well as from adult respiratory samples. The study showed that 38.2% of the strains were nonsusceptible to penicillin, 19.3% nonsusceptible to amoxicillin, and 10.5% nonsusceptible to cefotaxime. The percentage of pneumococcus nonsusceptible to penicillin varied according to both the sample and the age of the patient (child/adult): blood (27.8%/32.5%), cerebrospinal fluid (33.7%/34.6%), middle ear fluid (60.2%/27.5%), and pleural fluid (50.0%/31.0%). Between 2003 and 2007, the frequency of penicillin resistance in invasive pneumococcal disease gradually decreased from 46.4% to 29.0% in children and from 43.8% to 32.7% in adults. This decrease coincided with the introduction of a seven-valent pneumococcal conjugate vaccine into immunization programs and with a general reduction in levels of antibiotic consumption in France