312 research outputs found
Biochemical reference values in elderly black subjects
Biochemical reference values for the black age group of â„ 65 years were determined from the black urban population of the Orange Free State. Biochemical investigations performed were those included in the Sequential Multiple Analyser Computer profile because it includes the 20 most requested clinical chemistry investigations. Most of the reference values corresponded to values for the same age groups in the Western world. There was no age-related rise in the alkaline phosphatase values, which suggested absence of occult Paget's disease. Reference values for serum total protein and globulin were found to be higher than values derived from elderly white groups
The effect of current Schistosoma mansoni infection on the immunogenicity of a candidate TB vaccine, MVA85A, in BCG-vaccinated adolescents: An open-label trial.
INTRODUCTION: Helminth infection may affect vaccine immunogenicity and efficacy. Adolescents, a target population for tuberculosis booster vaccines, often have a high helminth burden. We investigated effects of Schistosoma mansoni (Sm) on the immunogenicity and safety of MVA85A, a model candidate tuberculosis vaccine, in BCG-vaccinated Ugandan adolescents. METHODS: In this phase II open label trial we enrolled 36 healthy, previously BCG-vaccinated adolescents, 18 with no helminth infection detected, 18 with Sm only. The primary outcome was immunogenicity measured by Ag85A-specific interferon gamma ELISpot assay. Tuberculosis and schistosome-specific responses were also assessed by whole-blood stimulation and multiplex cytokine assay, and by antibody ELISAs. RESULTS: Ag85A-specific cellular responses increased significantly following immunisation but with no differences between the two groups. Sm infection was associated with higher pre-immunisation Ag85A-specific IgG4 but with no change in antibody levels following immunisation. There were no serious adverse events. Most reactogenicity events were of mild or moderate severity and resolved quickly. CONCLUSIONS: The significant Ag85A-specific T cell responses and lack of difference between Sm-infected and uninfected participants is encouraging for tuberculosis vaccine development. The implications of pre-existing Ag85A-specific IgG4 antibodies for protective immunity against tuberculosis among those infected with Sm are not known. MVA85A was safe in this population. TRIAL REGISTRATION: ClinicalTrials.gov NCT02178748
Limits on Stellar and Planetary Companions in Microlensing Event OGLE-1998-BUL-14
We present the PLANET photometric data set for \ob14, a high magnification
() event alerted by the OGLE collaboration toward the
Galactic bulge in 1998. The PLANET data set consists a total of 461 I-band and
139 band points, the majority of which was taken over a three month period.
The median sampling interval during this period is about 1 hour, and the
scatter over the peak of the event is 1.5%. The excellent data
quality and high maximum magnification of this event make it a prime candidate
to search for the short duration, low amplitude perturbations that are
signatures of a planetary companion orbiting the primary lens. The observed
light curve for \ob14 is consistent with a single lens (no companion) within
photometric uncertainties. We calculate the detection efficiency of the light
curve to lensing companions as a function of the mass ratio and angular
separation of the two components. We find that companions of mass ratio are ruled out at the 95% confidence level for projected separations
between 0.4-2.4 \re, where \re is the Einstein ring radius of the primary
lens. Assuming that the primary is a G-dwarf with \re\sim3 {\rm AU} our
detection efficiency for this event is for a companion with the mass
and separation of Jupiter and for a companion with the mass and
separation of Saturn. Our efficiencies for planets like those around Upsilon
And and 14 Her are > 75%.Comment: Data available at http://www.astro.rug.nl/~planet/planetpapers.html
20 pages, 10 figures. Minor changes. ApJ, accepte
An investigation into the use of <â38 ”m fraction as a proxy for <â10 ”m road dust particles
It is well documented that a large portion of urban particulate matters is derived from road dust. Isolating particles of RD which are small enough to be inhaled, however, is a difficult process. In this study, it is shown for the first time that the <â38 ”m fraction of road dust particles can be used as a proxy for road dust particles <â10 ”m in bioaccessibility studies. This study probed similarities between the <â10 andâ<â38”m fractions of urban road dust to show that the larger of the two can be used for analysis for which larger sample masses are required, as is the case with in vitro analysis. Road dust, initially segregated to size <â38 ”m using sieves, was again size segregated to <â10 ”m using water deposition. Both the original <â38 ”m and the separated <â10 ”m fractions were then subject to single particle analysis by SEMâEDX and bulk analysis by ICP-OES for its elemental composition. Dissolution tests in artificial lysosomal fluid, representative of lung fluid, were carried out on both samples to determine % bioaccessibility of selected potentially harmful elements and thus probe similarities/differences in in vitro behaviour between the two fractions. The separation technique achieved 94.3% of particles <â10 ”m in terms of number of particles (the original sample contained 90.4% as determined by SEMâEDX). Acid-soluble metal concentration results indicated differences between the samples. However, when manipulated to negate the input of Si, SEMâEDX data showed general similarities in metal concentrations. Dissolution testing results indicated similar behaviour between the two samples in a simulated biological fluid
A Complete Set of Solutions For Caustic-Crossing Binary Microlensing Events
We present a method to analyze binary-lens microlensing light curves with one
well-sampled fold caustic crossing. In general, the surface of chi^2 shows
extremely complicated behavior over the 9-parameter space that characterizes
binary lenses. This makes it difficult to systematically search the space and
verify that a given local minimum is a global minimum. We show that for events
with well-monitored caustics, the caustic-crossing region can be isolated from
the rest of the light curve and easily fit to a 5-parameter function. Four of
these caustic-crossing parameters can then be used to constrain the search in
the larger 9-parameter space. This allows a systematic search for all solutions
and thus identification of all local minima. We illustrate this technique using
the PLANET data for MACHO 98-SMC-1, an excellent and publicly available
caustic-crossing data set. We show that a very broad range of parameter
combinations are compatible with the PLANET data set, demonstrating that
observations of binary-lens lightcurves with sampling of only one caustic
crossing do not yield unique solutions. The corollary to this is that the time
of the second caustic crossing cannot be reliably predicted on the basis of
early data including the first caustic crossing alone. We investigate the
requirements for determination of a unique solution and find that occasional
observations of the first caustic crossing may be sufficient to derive a
complete solution.Comment: 31 pages + 8 figures + 2 table
A scoping study of component-specific toxicity of mercury in urban road dusts from three international locations
This scoping study presents an investigation of the total and bioaccessible mercury concentrations in road dust (RD) from three international urban sites, where a one-off sampling campaign was conducted at each. This was done to address the hypothesis that the matrix in which mercury is found influences its ability to become accessible to the body once inhaled. For that purpose, the samples were analysed for total and pulmonary bioaccessible mercury and the data compared to the chemical structure of individual particles by SEM. The results obtained from this study suggest that a high mercury content does not necessarily equate to high bioaccessibility, a phenomenon which could be ascribed to the chemical character of the individual particles. It was found that the Manchester samples contained more pulmonary soluble mercury species (as determined by elemental associations of Hg and Cl) in comparison to the other two samples, Curitiba, Brazil, and Johannesburg, South Africa. This finding ultimately underlines the necessity to conduct a site-specific in-depth analysis of RD, to determine the concentration, chemical structure and molecular speciation of the materials within the complex matrix of RD. Therefore, rather than simply assuming that higher bulk concentrations equate to more significant potential human health concerns, the leaching potential of the metal/element in its specific form (for example as a mineral) should be ascertained. The importance of individual particle behaviour in the determination of human health risk is therefore highlighted
Sub-threshold resonances in few-neutron systems
Three- and four-neutron systems are studied within the framework of the
hyperspherical approach with a local S-wave nn-potential. Possible bound and
resonant states of these systems are sought as zeros of three- and four-body
Jost functions in the complex momentum plane. It is found that zeros closest to
the origin correspond to sub-threshold (nnn) (1/2-) and (nnnn) (0+) resonant
states. The positions of these zeros turned out to be sensitive to the choice
of the --potential. For the Malfliet- Tjon potential they are
E(nnn)=-4.9-i6.9 (MeV) and E(nnnn)=-2.6-i9.0 (MeV). Movement of the zeros with
an artificial increase of the potential strength also shows an extreme
sensitivity to the choice of potential. Thus, to generate ^3n and ^4n bound
states, the Yukawa potential needs to be multiplied by 2.67 and 2.32
respectively, while for the Malfliet-Tjon potential the required multiplicative
factors are 4.04 and 3.59.Comment: Latex, 22 pages, no PS-figures, submitted to J.Phys.
Limb-Darkening of a K Giant in the Galactic Bulge: PLANET Photometry of MACHO 97-BLG-28
We present the PLANET photometric dataset for the binary-lens microlensing
event MACHO 97-BLG-28 consisting of 696 I and V-band measurements, and analyze
it to determine the radial surface brightness profile of the Galactic bulge
source star. The microlensed source, demonstrated to be a K giant by our
independent spectroscopy, crossed the central isolated cusp of the lensing
binary, generating a sharp peak in the light curve that was well-resolved by
dense (3 - 30 minute) and continuous monitoring from PLANET sites in Chile,
South Africa, and Australia. Our modeling of these data has produced stellar
profiles for the source star in the I and V bands that are in excellent
agreement with those predicted by stellar atmospheric models for K giants. The
limb-darkening coefficients presented here are the first derived from
microlensing, among the first for normal giants by any technique, and the first
for any star as distant as the Galactic bulge. Modeling indicates that the
lensing binary has a mass ratio q = 0.23 and an (instantaneous) separation in
units of the angular Einstein ring radius of d = 0.69 . For a lens in the
Galactic bulge, this corresponds to a typical stellar binary with a projected
separation between 1 and 2 AU. If the lens lies closer, the separation is
smaller, and one or both of the lens objects is in the brown dwarf regime.
Assuming that the source is a bulge K2 giant at 8 kpc, the relative lens-source
proper motion is mu = 19.4 +/- 2.6 km/s /kpc, consistent with a disk or bulge
lens. If the non-lensed blended light is due to a single star, it is likely to
be a young white dwarf in the bulge, consistent with the blended light coming
from the lens itself.Comment: 32 Pages, including 1 table and 9 postscript figures. (Revised
version has slightly modified text, corrected typo, and 1 new figure.)
Accepted for publication in 1999 Astrophysical Journal; data are now
available at http://www.astro.rug.nl/~plane
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