80 research outputs found
Natural Haemophilus influenzae type b capsular polysaccharide antibodies in 412 infants and children from West Africa (Burkina-Faso) and France: a cross-sectional serosurvey.
Prior to possible introduction of large-scale vaccination programmes, an estimation and comparison of naturally acquired immunity against Haemophilus influenzae type b (Hib) was carried out in two populations of age-stratified infants and children (from birth to 14 years old) in Burkina-Faso (West Africa) (n = 206) and France (n = 206). Hib capsular polysaccharide antibodies were detected by an ELISA method. The difference in the percentages of minimum protective levels for the two populations were not significant (0.15 microg/ml) for newborns (0-1 month) but became significant as early as 2 to 3 months of age (p < 0.01) when lower levels were found among infants from Burkina-Faso. Subsequently, the percentages in both countries remained low until 11 months of age and showed no significant differences. For children between 12 and 35 months, the results > or = 0.15 microg/ml were significantly higher in France (p < or = 0.05). From 36 months, the percentage of minimum seropositivity increased in Burkina-Faso, so that the difference was no longer significant. In each country, the percentage of children with the minimum protective level varied significantly (p < or = 0.05) according to age (0-47 months). None of the children from Burkina-Faso or France had antibody levels > 1.0 microg/ml before one year of age. Thereafter, only 9.51% of French children in the 12- to 17-month age stratum and 19.2% over 4 years of age had antibody levels > 1.0 microg/ml. There were no non-detectable results for children over 4 years of age, and the means for natural detectable Hib CP antibodies were > 0.15 microg/ml for both populations. Hib invasive infections depend on climate, socioeconomic status and ethnic and genetic factors. In Burkina-Faso, the large number of infants and children under 4 years of age susceptible to Hib infections suggests that large scale vaccination programmes are needed soon after birth. However, it would first be necessary to evaluate such factors as the frequency of Hib diseases in this population
Mise en place dâoutils dâaide Ă la prescription des antibiotiques dans les Ă©tablissements de santĂ© (ES) des Pays de la Loire : crĂ©ation dâun thĂ©saurus rĂ©gional de protocoles dâantibiothĂ©rapie
Date du colloque : 2008</p
Simulation of Laser Propagation in a Plasma with a Frequency Wave Equation
The aim of this work is to perform numerical simulations of the propagation
of a laser in a plasma. At each time step, one has to solve a Helmholtz
equation in a domain which consists in some hundreds of millions of cells. To
solve this huge linear system, one uses a iterative Krylov method with a
preconditioning by a separable matrix. The corresponding linear system is
solved with a block cyclic reduction method. Some enlightments on the parallel
implementation are also given. Lastly, numerical results are presented
including some features concerning the scalability of the numerical method on a
parallel architecture
A 10-hour period revealed in optical spectra of the highly variable WN8 Wolf-Rayet star WR 123
Aims. What is the origin of the large-amplitude variability in Wolf-Rayet WN8
stars in general and WR123 in particular? A dedicated spectroscopic campaign
targets the ten-hour period previously found in the high-precision photometric
data obtained by the MOST satellite. Methods. In June-August 2003 we obtained a
series of high signal-to-noise, mid-resolution spectra from several sites in
the {\lambda}{\lambda} 4000 - 6940 A^{\circ} domain. We also followed the star
with occasional broadband (Johnson V) photometry. The acquired spectroscopy
allowed a detailed study of spectral variability on timescales from \sim 5
minutes to months. Results. We find that all observed spectral lines of a given
chemical element tend to show similar variations and that there is a good
correlation between the lines of different elements, without any significant
time delays, save the strong absorption components of the Hei lines, which tend
to vary differently from the emission parts. We find a single sustained
periodicity, P \sim 9.8 h, which is likely related to the relatively stable
pulsations found in MOST photometry obtained one year later. In addition,
seemingly stochastic, large-amplitude variations are also seen in all spectral
lines on timescales of several hours to several days.Comment: 6 pages, 4 figures, 2 tables, data available on-line, accepted in A&A
Research Note
The Seroepidemiology of Haemophilus influenzae Type B Prior to Introduction of an Immunization Programme in Kathmandu, Nepal.
Haemophilus influenzae type b (Hib) is now recognized as an important pathogen in Asia. To evaluate disease susceptibility, and as a marker of Hib transmission before routine immunization was introduced in Kathmandu, 71 participants aged 7 months-77 years were recruited and 15 cord blood samples were collected for analysis of anti-polyribosylribitol phosphate antibody levels by enzyme-linked immunosorbent assay. Only 20% of children under 5 years old had levels considered protective (>0.15 ”g/ml), rising to 83% of 15-54 year-olds. Prior to introduction of Hib vaccine in Kathmandu, the majority of young children were susceptible to disease
The spinning-top Be star Achernar from VLTI-VINCI
We report here the first observations of a rapidly rotating Be star,
Eridani, using Earth-rotation synthesis on the Very Large Telescope (VLT)
Interferometer. Our measures correspond to a apparent
oblate star, and being the equivalent uniform disc angular diameters
in the equatorial and polar direction. Considering the presence of a
circumstellar envelope (CSE) we argue that our measurement corresponds to a
truly distorted star since Eridani exhibited negligible H
emission during the interferometric observations. In this framework we conclude
that the commonly adopted Roche approximation (uniform rotation and centrally
condensed mass) should not apply to Eridani. This result opens new
perspectives to basic astrophysical problems, such as rotationally enhanced
mass loss and internal angular momentum distribution. In addition to its
intimate relation with magnetism and pulsation, rapid rotation thus provides a
key to the Be phenomenon: one of the outstanding non-resolved problems in
stellar physics.Comment: 5 pages, 3 figures, Accepted for Publication in A&A Lette
Using honey to heal diabetic foot ulcers
Diabetic ulcers seem to be arrested in the inflammatory/proliferative stage of the healing process, allowing infection and inflammation to preclude healing. Antibiotic-resistant bacteria have become a major cause of infections, including diabetic foot infections. It is proposed here that the modern developments of an ancient and traditional treatment for wounds, dressing them with honey, provide the solution to the problem of getting diabetic ulcers to move on from the arrested state of healing. Honeys selected to have a high level of antibacterial activity have been shown to be very effective against antibiotic-resistant strains of bacteria in laboratory and clinical studies. The potent anti-inflammatory action of honey is also likely to play an important part in overcoming the impediment to healing that inflammation causes in diabetic ulcers, as is the antioxidant activity of honey. The action of honey in promotion of tissue regeneration through stimulation of angiogenesis and the growth of fibroblasts and epithelial cells, and its insulin-mimetic effect, would also be of benefit in stimulating the healing of diabetic ulcers. The availability of honey-impregnated dressings which conveniently hold honey in place on ulcers has provided a means of rapidly debriding ulcers and removing the bacterial burden so that good healing rates can be achieved with neuropathic ulcers. With ischemic ulcers, where healing cannot occur because of lack of tissue viability, these honey dressings keep the ulcers clean and prevent infection occurring
Abundance analysis of targets for the COROT / MONS asteroseimology missions I. Semi-automatic abundance analysis of the gamma Dor star HD 49434
One of the goals of the ground-based support program for the COROT and
MONS/Roemer satellite missions is to select and characterise suitable target
stars for the part of the missions dedicated to asteroseismology. While the
global atmospheric parameters may be determined with good accuracy from the
Stromgren indices, careful abundance analysis must be made for the proposed
main targets. This is a time consuming process considering the long list of
primary and secondary targets. We have therefore developed new software called
VWA for this task. The VWA automatically selects the least blended lines from
the atomic line database VALD, and consequently adjusts the abundance in order
to find the best match between the calculated and observed spectra. The
variability of HD 49434 was discovered as part of COROT ground-based support
observations. Here we present a detailed abundance analysis of HD 49434 using
VWA. For most elements we find abundances somewhat below the Solar values, in
particular we find [Fe/H] = -0.13(14). We also present the results from the
study of the variability that is seen in spectroscopic and photometric time
series observations. From the characteristics of the variation seen in
photometry and in the line profiles we propose that HD 49434 is a variable star
of the gamma Doradus type.Comment: 10 pages, 6 figure
Preparing the COROT space mission: incidence and characterisation of pulsation in the Lower Instability Strip
By pursuing the goal to find new variables in the COROT field-of-view we
characterised a sample of stars located in the lower part of the instability
strip. Our sample is composed of stars belonging to the disk population in the
solar neighbourhood. We found that 23% of the stars display multiperiodic light
variability up to few mmag of amplitude. uvbyBeta photometry fixed most of the
variables in the middle of the instability strip and high-resolution
spectroscopy established that they have vsin i>100 km/s. The comparison with
delta Sct stars in the whole Galaxy shows slightly different features, i.e.,
most delta Sct stars have a 0.05-mag redder (b-y)_0 index and lower vsin i
values. Additional investigation in the open cluster NGC 6633 confirms the same
incidence of variability, i.e., around 20%. The wide variety of pulsational
behaviours of delta Sct stars (including unusual objects such as a variable
beyond the blue edge or a rapidly rotating high-amplitude pulsator) makes them
very powerful asteroseismic tools to be used by COROT. Being quite common among
bright stars, delta Sct stars are suitable targets for optical observations
from space.Comment: 9 pages, 9 figures Accepted for publication in Astronomy &
Astrophysics, Main Journa
Abundance analysis of targets for the COROT/MONS asteroseismology missions II. Abundance analysis of the COROT main targets
One of the goals of the ground-based support program for the COROT and MONS/RĂMER satellite missions is to characterize suitable target stars for the part of the missions dedicated to asteroseismology. We present the detailed abundance analysis of nine of the potential COROT main targets using the semi-automatic software VWA. For two additional COROT targets we could not perform the analysis due to the high rotational velocity of these stars. For five stars with low rotational velocity we have also performed abundance analysis by a classical equivalent width method in order to test the reliability of the VWA software. The agreement between the different methods is good. We find that it is necessary to measure abundances extracted from each line relative to the abundances found from a spectrum of the Sun in order to remove systematic errors. We have constrained the global atmospheric parameters Teff log g, and [Fe/H] to within 70-100 K, 0.1-0.2 dex, and 0.1 dex for five stars which are slow rotators (Îœ sin i 60 km s-1) it is not possible to constrain the atmospheric parameters
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