80 research outputs found
Exploring the barriers and facilitators to the acceptability of donor human milk in eastern Uganda - a qualitative study
Effect on nasopharyngeal pneumococcal carriage of replacing PCV7 with PCV13 in the Expanded Programme of Immunization in The Gambia.
INTRODUCTION: In 2011, two years after the introduction of 7-valent Pneumococcal conjugate vaccine (PCV7), the Gambian immunization programme replaced PVC7 with PCV13 (13-valent). Our objective was to assess the additional impact of PCV13 on prevalence of pneumococcal nasopharyngeal carriage. METHODS: We recruited healthy Gambian infants who had received three PCV doses. Nasopharyngeal swabs were collected from infants and their mothers during two cross-sectional surveys (CSS) conducted in infants vaccinated with PCV7 (CSS1) and vaccinated with PCV13 (CSS2). Pneumococci were isolated and serotyped following standardized methods. Whole genome sequencing was performed on non-typable pneumococcus isolated in CSS1 and CSS2. RESULTS: 339 and 350 infants and their mothers were recruited in CSS1 and CSS2, respectively. Overall prevalence of pneumococcal carriage was 85.4% in infants. Among infants, prevalence of vaccine type (VT) carriage was lower in CSS2 [9.4% versus 4.9% (p=0.025) for PCV7-VT; 33.3% versus 18.3% (p<0.001) for PCV13-VT and 23.9% versus 13.7% (p=0.001) for the 6 additional serotypes included in PCV13]. At CSS2, there was a decrease of serotypes 6A (from 15.3% to 5.7%, p<0.001) and 19F (from 5.6% to 1.7%, p=0.007), and an increase of non-typable pneumococci (0.3-6.0%, p<0.001), most of which (82.4%) were from typable serotype backgrounds that had lost the ability to express a capsule. Prevalence of overall and VT carriage in mothers was similar in CSS1 and CSS2. CONCLUSIONS: Replacing PCV7 for PCV13 rapidly decreased prevalence of VT carriage among vaccinated Gambian infants. An indirect effect in mothers was not observed yet. Vaccine-driven selection pressure may have been responsible for the increase of non-typable isolates
Mass drug administration with azithromycin for trachoma elimination and the population structure of Streptococcus pneumoniae in the nasopharynx
ABSTRACTBackgroundMass drug administration (MDA) with azithromycin for trachoma elimination reduces nasopharyngeal carriage of Streptococcus pneumoniae in the short term. We evaluated S. pneumoniae carried in the nasopharynx before and after a round of azithromycin MDA to determine whether MDA was associated with changes in pneumococcal population structure.MethodsWe analysed 514 pneumococcal isolates cultured from nasopharyngeal samples collected in Gambian villages that received MDA for trachoma elimination. The samples were collected during three cross-sectional surveys conducted before the third round of MDA (CSS-1) and at one (CSS-2) and six (CSS-3) months after MDA. Whole genome sequencing was conducted on randomly selected isolates. Bayesian Analysis of Population Structure (BAPS) was used to cluster related isolates by capturing variation in the core genome. Serotype and multi-locus sequence type were inferred from the genotype. The Antimicrobial Resistance Identification by Assembly (ARIBA) tool was used to identify macrolide resistance genes.ResultsTwenty-seven BAPS clusters were assigned. These consisted of 81 sequence types (STs), 15 of which were novel additions to pubMLST. Two BAPS clusters, BAPS20 (p-value<=0.016) and BAPS22 (p-value<=0.032) showed an increase in frequency at CSS-3 not associated with antimicrobial resistance. Macrolide resistance within BASP17 increased after treatment (p<0.05) and was carried on a mobile transposable element that also conferred resistance to tetracycline.ConclusionsLimited changes in pneumococcal population structure were observed after the third round of MDA suggesting treatment had little effect on the circulating lineages. An increase in macrolide resistance within one BAPS highlights the need for antimicrobial resistance surveillance in treated villages.</jats:sec
The complex behavior of the satellite footprints at Jupiter: the result of universal processes?
At Jupiter, some auroral emissions are directly related to the electromagnetic interaction between the moons Io, Europa and Ganymede on one hand and the rapidly rotating magnetospheric plasma on the other hand. Out of the three, the Io footprint is the brightest and the most studied. Present in each hemisphere, it is made of at least three different spots and an extended trailing tail. The variability of the brightness of the spots as well as their relative location has been tentatively explained with a combination of AlfvĂ©n wavesâ partial reflections on density gradients and bi-directional electron acceleration at high latitude. Should this scenario be correct, then the other footprints should also show the same behavior.
Here we show that all footprints are, at least occasionally, made of several spots and they all display a tail. We also show that these spots share many characteristics with those of the Io footprint (i.e. some significant variability on timescales of 2-3 minutes). Additionally, we present some Monte-Carlo simulations indicating that the tails are also due to Alfvén waves electron acceleration rather than quasi-static electron acceleration. Even if some details still need clarification, these observations strengthen the scenario proposed for the Io footprint and thus indicate that these processes are universal.
In addition, we will present some early results from Juno-UVS concerning the location and morphology of the footprints during the first low-altitude observations of the polar aurorae. These observations, carried out in previously unexplored longitude ranges, should either confirm or contradict our understanding of the footprints
The Deep Water Abundance on Jupiter: New Constraints from Thermochemical Kinetics and Diffusion Modeling
We have developed a one-dimensional thermochemical kinetics and diffusion
model for Jupiter's atmosphere that accurately describes the transition from
the thermochemical regime in the deep troposphere (where chemical equilibrium
is established) to the quenched regime in the upper troposphere (where chemical
equilibrium is disrupted). The model is used to calculate chemical abundances
of tropospheric constituents and to identify important chemical pathways for
CO-CH4 interconversion in hydrogen-dominated atmospheres. In particular, the
observed mole fraction and chemical behavior of CO is used to indirectly
constrain the Jovian water inventory. Our model can reproduce the observed
tropospheric CO abundance provided that the water mole fraction lies in the
range (0.25-6.0) x 10^-3 in Jupiter's deep troposphere, corresponding to an
enrichment of 0.3 to 7.3 times the protosolar abundance (assumed to be H2O/H2 =
9.61 x 10^-4). Our results suggest that Jupiter's oxygen enrichment is roughly
similar to that for carbon, nitrogen, and other heavy elements, and we conclude
that formation scenarios that require very large (>8 times solar) enrichments
in water can be ruled out. We also evaluate and refine the simple time-constant
arguments currently used to predict the quenched CO abundance on Jupiter, other
giant planets, and brown dwarfs.Comment: 42 pages, 7 figures, 4 tables, with note added in proof. Accepted for
publication in Icarus [in press
Jupiter's X-ray Emission During Solar Minimum
The 2007â2009 solar minimum was the longest of the space age. We present the first of two companion papers on Chandra and XMMâNewton Xâray campaigns of Jupiter through FebruaryâMarch 2007. We find that low solar Xâray flux during solar minimum causes Jupiter's equatorial regions to be exceptionally Xâray dim (0.21 GW at minimum; 0.76 GW at maximum). While the Jovian equatorial emission varies with solar cycle, the aurorae have comparably bright intervals at solar minimum and maximum. We apply atomic charge exchange models to auroral spectra and find that iogenic plasma of sulphur and oxygen ions provides excellent fits for XMMâNewton observations. The fitted spectral S:O ratios of 0.4â1.3 are in good agreement with in situ magnetospheric S:O measurements of 0.3â1.5, suggesting that the ions that produce Jupiter's Xâray aurora predominantly originate inside the magnetosphere. The aurorae were particularly bright on 24â25 February and 8â9 March, but these two observations exhibit very different spatial, spectral, and temporal behavior; 24â25 February was the only observation in this campaign with significant hard Xâray bremsstrahlung from precipitating electrons, suggesting this may be rare. For 8â9 March, a bremsstrahlung component was absent, but bright oxygen O6+ lines and bestâfit models containing carbon, point to contributions from solar wind ions. This contribution is absent in the other observations. Comparing simultaneous Chandra ACIS and XMMâNewton EPIC spectra showed that ACIS systematically underreported 0.45â to 0.6âkeV Jovian emission, suggesting quenching may be less important for Jupiter's atmosphere than previously thought. We therefore recommend XMMâNewton for spectral analyses and quantifying opacity/quenching effects
Jupiter's X-ray Emission 2007 Part 2:Comparisons with UV and Radio Emissions and In-Situ Solar Wind Measurements
We compare Chandra and XMMâNewton Xâray observations of Jupiter during 2007 with a rich multiâinstrument dataset including: upstream inâsitu solar wind measurements from the New Horizons spacecraft, radio emissions from the Nançay Decametric Array and Wind/Waves, and UV observations from the Hubble Space Telescope. New Horizons data revealed two corotating interaction regions (CIRs) impacted Jupiter during these observations. NonâIo decametric bursts and UV emissions brightened together and varied in phase with the CIRs. We characterise 3 types of Xâray aurorae: hard Xâray bremsstrahlung main emission, pulsed/flared soft Xâray emissions and a newly identified dim flickering (varying on shortâtimescales, but quasiâcontinuously present) aurora. For most observations, the Xâray aurorae were dominated by pulsed/flaring emissions, with ion spectral lines that were best fit by Iogenic plasma. However, the brightest Xâray aurora was coincident with a magnetosphere expansion. For this observation, the aurorae were produced by both flickering emission and erratic pulses/flares. Auroral spectral models for this observation required the addition of solar wind ions to attain good fits, suggesting solar wind entry into the outer magnetosphere or directly into the pole for this particularly bright observation. Xâray bremsstrahlung from high energy electrons was only bright for one observation, which was during a forward shock. This bremsstrahlung was spatially coincident with bright UV main emission (power> 1TW) and Xâray ion spectral line dusk emission, suggesting closening of upward and downward current systems during the shock. Otherwise, the bremsstrahlung was dim and UV main emission power was also lower(<700 GW), suggesting their power scaled together
Improved Neurodevelopment After Initiation of Antiretroviral Therapy in Human Immunodeficiency Virus-infected Children
Post-neonatal Mortality, Morbidity, and Developmental Outcome after Ultrasound-Dated Preterm Birth in Rural Malawi: A Community-Based Cohort Study
Using data collected as a follow-up to a randomized trial, Melissa Gladstone and colleagues show that during the first two years of life, infants born preterm in southern Malawi are disadvantaged in terms of mortality, growth, and development
Jupiterâs auroras during the Juno approach phase as observed by the Hubble Space Telescope
We present movies of the Hubble Space Telescope (HST) observations of Jupiterâs FUV auroras observed during the Juno approach phase and first capture orbit, and compare with Juno observations of the interplanetary medium near Jupiter and inside the magnetosphere. Jupiterâs FUV auroras indicate the nature of the dynamic processes occurring in Jupiterâs magnetosphere, and the approach phase provided a unique opportunity to obtain a full set of interplanetary data near to Jupiter at the time of a program of HST observations, along with the first simultaneous with Juno observations inside the magnetosphere. The overall goal was to determine the nature of the solar wind effect on Jupiterâs magnetosphere. HST observations were obtained with typically 1 orbit per day over three intervals: 16 May â 7 June, 22-30 June and 11-18 July, i.e. while Juno was in the solar wind, around the bow shock and magnetosphere crossings, and in the mid-latitude middle-outer magnetospheres. We show that these intervals are characterised by particularly dynamic polar auroras, and significant variations in the auroral power output caused by e.g. dawn storms, intense main emission and poleward forms. We compare the variation of these features with Juno observations of interplanetary compression regions and the magnetospheric environment during the intervals of these observations
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