547 research outputs found
Antiretroviral Therapy outcomes among adolescents and youth in rural Zimbabwe
Around 2 million adolescents and 3 million youth are estimated to be living with HIV worldwide. Antiretroviral outcomes for this group appear to be worse compared to adults. We report antiretroviral therapy outcomes from a rural setting in Zimbabwe among patients aged 10-30 years who were initiated on ART between 2005 and 2008. The cohort was stratified into four age groups: 10-15 (young adolescents) 15.1-19 years (adolescents), 19.1-24 years (young adults) and 24.1-29.9 years (older adults). Survival analysis was used to estimate rates of deaths and loss to follow-up stratified by age group. Endpoints were time from ART initiation to death or loss to follow-up. Follow-up of patients on continuous therapy was censored at date of transfer, or study end (31 December 2008). Sex-adjusted Cox proportional hazards models were used to estimate hazard ratios for different age groups. 898 patients were included in the analysis; median duration on ART was 468 days. The risk of death were highest in adults compared to young adolescents (aHR 2.25, 95%CI 1.17-4.35). Young adults and adolescents had a 2-3 times higher risk of loss to follow-up compared to young adolescents. When estimating the risk of attrition combining loss to follow-up and death, young adults had the highest risk (aHR 2.70, 95%CI 1.62-4.52). This study highlights the need for adapted adherence support and service delivery models for both adolescents and young adults
Fenestration of the vertebrobasilar junction detected with multidetector computed tomography angiography
The complex embryonic origin of the vertebrobasilar system may result in a wide range of anatomical variations. It has been hypothesized that the formation of fenestrations are likely to occur due to the failure of regression of the bridging arteries that connect the longitudinal neural arteries during embryogenesis. Fenestration of the vertebrobasilar system is a rare anatomical variation that involves a luminal division of the artery, that has a single origin into two separate and parallel channels which are rejoined distally. Fenestrations are important anatomical variants in patients undergoing endovascular and invasive intracranial interventions. Vascular fenestration has been associated with aneurysms, arteriovenous malformations, neuralgia, and vertebrobasilar ischaemia. We report on 3 cases of fenestration at the vertebrobasilar junction in 1 female and 2 male patients, respectively, using multidetector computed tomography angiography. The length of the fenestrated segment of the artery measured 4.41 mm, 3.90 mm, and 5.90 mm, respectively in the patients. Our report is clinically important as the presence of this anatomical variation may influence the management of cervical and intracranial pathologies. Increased awareness of the prevalence of anatomic variations contributes to the advancement of noninvasive imaging capabilities
Remarkable thermal conductivity enhancement in Ag—decorated graphene nanocomposites based nanofluid by laser liquid solid interaction in ethylene glycol
We report on the synthesis and enhanced thermal conductivity of stable Ag-decorated 2-D graphene nanocomposite in ethylene glycol based nanofluid by laser liquid solid interaction. A surfactant free nanofluid of Ag nanoparticles anchored onto the 2-D graphene sheets were synthesized using a two-step laser liquid solid interaction approach. In order to understand a pulsed Nd:YAG laser at the fundamental frequency (λ = 1,064 nm) to ablate Ag and graphite composite target submerged in ethylene glycol (EG) to form AgNPs decorated 2-D GNs-EG based nanofluid. From a heat transfer point of view, it was observed that the thermal conductivity of this stable Ag-graphene/EG is significantly enhanced by a factor of about 32.3%; this is highest reported value for a graphene based nanofluid
MeerTime - the MeerKAT Key Science Program on Pulsar Timing
The MeerKAT telescope represents an outstanding opportunity for radio pulsar
timing science with its unique combination of a large collecting area and
aperture efficiency (effective area 7500 m), system temperature
(K), high slew speeds (1-2 deg/s), large bandwidths (770 MHz at 20cm
wavelengths), southern hemisphere location (latitude ) and
ability to form up to four sub-arrays. The MeerTime project is a five-year
program on the MeerKAT array by an international consortium that will regularly
time over 1000 radio pulsars to perform tests of relativistic gravity, search
for the gravitational wave signature induced by supermassive black hole
binaries in the timing residuals of millisecond pulsars, explore the interiors
of neutron stars through a pulsar glitch monitoring programme, explore the
origin and evolution of binary pulsars, monitor the swarms of pulsars that
inhabit globular clusters and monitor radio magnetars. In addition to these
primary programmes, over 1000 pulsars will have their arrival times monitored
and the data made immediately public. The MeerTime pulsar backend comprises two
server-class machines each of which possess four Graphics Processing Units. Up
to four pulsars can be coherently dedispersed simultaneously up to dispersion
measures of over 1000 pc cm. All data will be provided in psrfits
format. The MeerTime backend will be capable of producing coherently
dedispersed filterbank data for timing multiple pulsars in the cores of
globular clusters that is useful for pulsar searches of tied array beams. All
MeerTime data will ultimately be made available for public use, and any
published results will include the arrival times and profiles used in the
results.Comment: 15 pages, MeerKAT Science: On the Pathway to the SKA, 25-27 May,
2016, Stellenbosch, South Africa, available at:
https://pos.sissa.it/277/011/pd
MeerKLASS: MeerKAT Large Area Synoptic Survey
We discuss the ground-breaking science that will be possible with a wide area
survey, using the MeerKAT telescope, known as MeerKLASS (MeerKAT Large Area
Synoptic Survey). The current specifications of MeerKAT make it a great fit for
science applications that require large survey speeds but not necessarily high
angular resolutions. In particular, for cosmology, a large survey over for hours will potentially provide the first
ever measurements of the baryon acoustic oscillations using the 21cm intensity
mapping technique, with enough accuracy to impose constraints on the nature of
dark energy. The combination with multi-wavelength data will give unique
additional information, such as exquisite constraints on primordial
non-Gaussianity using the multi-tracer technique, as well as a better handle on
foregrounds and systematics. Such a wide survey with MeerKAT is also a great
match for HI galaxy studies, providing unrivalled statistics in the pre-SKA era
for galaxies resolved in the HI emission line beyond local structures at z >
0.01. It will also produce a large continuum galaxy sample down to a depth of
about 5\,Jy in L-band, which is quite unique over such large areas and
will allow studies of the large-scale structure of the Universe out to high
redshifts, complementing the galaxy HI survey to form a transformational
multi-wavelength approach to study galaxy dynamics and evolution. Finally, the
same survey will supply unique information for a range of other science
applications, including a large statistical investigation of galaxy clusters as
well as produce a rotation measure map across a huge swathe of the sky. The
MeerKLASS survey will be a crucial step on the road to using SKA1-MID for
cosmological applications and other commensal surveys, as described in the top
priority SKA key science projects (abridged).Comment: Larger version of the paper submitted to the Proceedings of Science,
"MeerKAT Science: On the Pathway to the SKA", Stellenbosch, 25-27 May 201
Corrections to the Gell-Mann-Oakes-Renner relation and chiral couplings and
Next to leading order corrections to the
Gell-Mann-Oakes-Renner relation (GMOR) are obtained using weighted QCD Finite
Energy Sum Rules (FESR) involving the pseudoscalar current correlator. Two
types of integration kernels in the FESR are used to suppress the contribution
of the kaon radial excitations to the hadronic spectral function, one with
local and the other with global constraints. The result for the pseudoscalar
current correlator at zero momentum is , leading to the chiral corrections to GMOR: . The resulting uncertainties are mostly due to variations in the upper
limit of integration in the FESR, within the stability regions, and to a much
lesser extent due to the uncertainties in the strong coupling and the strange
quark mass. Higher order quark mass corrections, vacuum condensates, and the
hadronic resonance sector play a negligible role in this determination. These
results confirm an independent determination from chiral perturbation theory
giving also very large corrections, i.e. roughly an order of magnitude larger
than the corresponding corrections in chiral . Combining
these results with our previous determination of the corrections to GMOR in
chiral , , we are able to determine two low
energy constants of chiral perturbation theory, i.e. , and , both at the
scale of the -meson mass.Comment: Revised version with minor correction
Anaerobe-enriched gut microbiota predicts pro-inflammatory responses in pulmonary tuberculosis
BACKGROUND: The relationship between tuberculosis (TB), one of the leading infectious causes of death worldwide, and the microbiome, which is critical for health, is poorly understood. METHODS: To identify potential microbiome-host interactions, profiling of the oral, sputum and stool microbiota [n = 58 cases, n = 47 culture-negative symptomatic controls (SCs)] and whole blood transcriptome were done in pre-treatment presumptive pulmonary TB patients. This was a cross-sectional study. Microbiota were also characterised in close contacts of cases (CCCs, n = 73) and close contacts of SCs (CCSCs, n = 82) without active TB. FINDINGS: Cases and SCs each had similar α- and β-diversities in oral washes and sputum, however, β-diversity differed in stool (PERMANOVA p = 0•035). Cases were enriched with anaerobes in oral washes, sputum (Paludibacter, Lautropia in both) and stool (Erysipelotrichaceae, Blautia, Anaerostipes) and their stools enriched in microbial genes annotated as amino acid and carbohydrate metabolic pathways. In pairwise comparisons with their CCCs, cases had Megasphaera-enriched oral and sputum microbiota and Bifidobacterium-, Roseburia-, and Dorea-depleted stools. Compared to their CCSCs, SCs had reduced α-diversities and many differential taxa per specimen type. Cases differed transcriptionally from SCs in peripheral blood (PERMANOVA p = 0•001). A co-occurrence network analysis showed stool taxa, Erysipelotrichaceae and Blautia, to negatively co-correlate with enriched "death receptor" and "EIF2 signalling" pathways whereas Anaerostipes positively correlated with enriched "interferon signalling", "Nur77 signalling" and "inflammasome" pathways; all of which are host pathways associated with disease severity. In contrast, none of the taxa enriched in SCs correlated with host pathways. INTERPRETATION: TB-specific microbial relationships were identified in oral washes, induced sputum, and stool from cases before the confounding effects of antibiotics. Specific anaerobes in cases' stool predict upregulation of pro-inflammatory immunological pathways, supporting the gut microbiota's role in TB. FUNDING: European & Developing Countries Clinical Trials Partnership, South African-Medical Research Council, National Institute of Allergy and Infectious Diseases
A Large Sky Survey with MeerKAT
We discuss the ground-breaking science that will be possible with a wide area survey, using
the MeerKAT telescope, known as MeerKLASS (MeerKAT Large Area Synoptic Survey). The
current specifications of MeerKAT make it a great fit for cosmological applications, which require
large volumes. In particular, a large survey over ~4,000 deg^2 for ~4,000 hours will potentially
provide the first ever measurements of the baryon acoustic oscillations using the 21cm intensity
mapping technique, with enough accuracy to impose constraints on the nature of dark energy. The
combination with multi-wavelength data will give unique additional information, such as the first
constraints on primordial non-Gaussianity using the multi-tracer technique, as well as a better
handle on foregrounds and systematics. The survey will also produce a large continuum galaxy
sample down to a depth of 5 µJy in L-band, unmatched by any other concurrent telescope, which
will allow to study the large-scale structure of the Universe out to high redshifts. Finally, the same
survey will supply unique information for a range of other science applications, including a large
statistical investigation of galaxy clusters, and the discovery of rare high-redshift AGN that can be
used to probe the epoch of reionization as well as produce a rotation measure map across a huge
swathe of the sky. The MeerKLASS survey will be a crucial step on the road to using SKA1-MID
for cosmological applications, as described in the top priority SKA key science projects
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