21,147 research outputs found
Research Gaps in Neonatal HIV-Related Care
The South African prevention of mother to child transmission programme has made excellent progress in reducing vertical HIV transmission, and paediatric antiretroviral therapy programmes have demonstrated good outcomes with increasing treatment initiation in younger children and infants. However, both in South Africa and across sub-Saharan African, lack of boosted peri-partum prophylaxis for high-risk vertical transmission, loss to followup, and failure to initiate HIV-infected infants on antiretroviral therapy (ART) before disease progression are key remaining gaps in neonatal HIV-related care. In this issue of the Southern African Journal of HIV Medicine, experts provide valuable recommendations for addressing these gaps. The present article highlights a number of areas where evidence is lacking to inform guidelines and programme development for optimal neonatal HIV-related care
Tartramide ligands for copper-catalyzed N-Arylation at room temperature
Abstract. A novel class of readily accessible tartramide ligands has been demonstrated to promote copper-catalysed N-arylation under mild conditions. In addition, the coupling protocol employs cheap and readily available pre-catalyst, ligand, and base (NaOH), and overcomes many current limitations often associated with Ullmann coupling: it can be run with low catalyst loadings, does not require the use of excess amine, gives excellent conversions at room temperature, is fully homogeneous, and displays improved tolerance to air and moisture. Detailed kinetic studies using reaction progress kinetic analysis (RPKA) methods have provided insight into the factors influencing the reaction rate in terms of impact of ligand structure, reactant / catalyst dependence and catalyst (in)stability. These kinetic insights have been used in a quality-by-design approach for further optimization of the reaction protocol. The reaction scope was extended to 22 examples, showing broad applicability for a wide range of substituted aryl iodides with both primary and secondary amines
The androgen receptor and signal-transduction pathways in hormone-refractory prostate cancer. Part 1: modifications to the androgen receptor
Prostate cancer is the second most common male malignancy in the western world an increasing incidence in an ageing population. Treatment of advanced prostate cancer relies on androgen deprivation. Although the majority of patients initially respond favourably to androgen deprivation therapy, the mean time to relapse is 12-18 months. Currently there are few treatments available for men who
have developed resistance to hormone therapy, due to the lack of understanding of the molecular mechanisms underlying development of this disease. Recently, however, major advances have been made in understanding both
androgen receptor (AR) dependent and independent pathways which promote development of hormone resistant prostate cancer. This review will focus on modifications to the AR and associated pathways. Molecular modifications to the
androgen receptor itself, e.g. mutations and/or amplification, although involved in the development of hormone resistance cannot explain all cases. Phosphorylation of AR, via either Ras/MAP kinase or PI3K/Akt signal transduction pathways, have been shown to activate AR in both a ligand (androgen) dependent and independent fashion. During this review we will discuss the clinical evidence to support AR dependent pathways as mediators of hormone resistance
Food additives and their health implications on children in Africa: a systematic review
Objective: The safety of processed foods is an issue of public health importance, especially in Africa
where there is unchecked rate at which many food industries turn out novel 'chemicals' aimed at increasing
the acceptability of their products. This is particularly true for processed foods targeted at children, who
remain the most vulnerable group. The aim of this review was to identify health implications of food
additives on children in Africa based on findings from original research works.
Methods: We conducted a parallel search of Medline, EMBASE and Global Health for relevant studies
from 1970 to 2014. We included studies conducted among African populations reporting effects of food
additives among children (under age 17 years). Data on health implications of food additives were
extracted and reviewed.
Results: Our search returned 479 studies, with only 4 studies meeting the selection criteria. Five countries
were represented, namely Libya, Nigeria, Uganda, Tanzania and Sudan The total study population was
3326. All the studies were cross-sectional, and focused essentially on sugar as an important risk factor for
the development of dental caries and/or erosion in children.
Conclusions: Studies on important food additives such as preservatives, colouring agents, sweeteners,
anti-caking agents and their effects on health of children are largely unavailable in Africa, although
anecdotal reports are suggestive of their deleterious effects. To ensure evidenced-based decision making
and public policies in this regard, there is a need for original research works
Update Frequency and Background Corpus Selection in Dynamic TF-IDF Models for First Story Detection
First Story Detection (FSD) requires a system to detect the very first story that mentions an event from a stream of stories. Nearest neighbour-based models, using the traditional term vector document representations like TF-IDF, currently achieve the state of the art in FSD. Because of its online nature, a dynamic term vector model that is incrementally updated during the detection process is usually adopted for FSD instead of a static model. However, very little research has investigated the selection of hyper-parameters and the background corpora for a dynamic model. In this paper, we analyse how a dynamic term vector model works for FSD, and investigate the impact of different update frequencies and background corpora on FSD performance. Our results show that dynamic models with high update frequencies outperform static model and dynamic models with low update frequencies; and that the FSD performance of dynamic models does not always increase with higher update frequencies, but instead reaches steady state after some update frequency threshold is reached. In addition, we demonstrate that different background corpora have very limited influence on the dynamic models with high update frequencies in terms of FSD performance
A Study of Gluon Propagator on Coarse Lattice
We study gluon propagator in Landau gauge with lattice QCD, where we use an
improved lattice action. The calculation of gluon propagator is performed on
lattices with the lattice spacing from 0.40 fm to 0.24 fm and with the lattice
volume from to . We try to fit our results by two
different ways, in the first one we interpret the calculated gluon propagators
as a function of the continuum momentum, while in the second we interpret the
propagators as a function of the lattice momentum. In the both we use models
which are the same in continuum limit. A qualitative agreement between two
fittings is found.Comment: Revtex 14pages, 11 figure
easySTORM: a robust, lower-cost approach to localisation and TIRF microscopy
TIRF and STORM microscopy are super-resolving fluorescence imaging modalities for which current implementations on standard microscopes can present significant complexity and cost. We present a straightforward and low-cost approach to implement STORM and TIRF taking advantage of multimode optical fibres and multimode diode lasers to provide the required excitation light. Combined with open source software and relatively simple protocols to prepare samples for STORM, including the use of Vectashield for non-TIRF imaging, this approach enables TIRF and STORM imaging of cells labelled with appropriate dyes or expressing suitable fluorescent proteins to become widely accessible at low cost
Structure of the clean Ta(100) surface
The clean Ta(100) surface and some aspects of hydrogen adsorption have been studied by LEED and AES. The thorough examination of LEED patterns did not provide any evidence for an atomic reconstruction of the clean surface over the entire temperature range investigated, 150–600 K. The r-factor analysis used for comparison between measured and calculated I–V spectra yields a contraction of the topmost layer spacing of about 11% and an expansion of the second layer spacing of about 1% compared to the bulk value. The hydrogen adsorption does not induce any superstructures, but small hydrogen exposures lass then 1 L influence I–V spectra substantially
Numerical evaluation of shear strength of CFS shear wall panels for different height-to-width ratios
This paper presents a numerical evaluation of the shear strength of Cold Formed Steel Shear Wall Panels (CFS-SWPs) having 1.33:1 and 1:1 height-to-width aspect ratios with 0.76 mm steel plate sheathing thickness and 1:4, 1.33:1 and 1:1 height-to-width aspect ratios with 0.46 mm steel plate sheathing thickness, which are not provided by AISI S400. For this purpose, shell finite element (FE) models, validated with test results, are completed in ABAQUS v2018 with nonlinear geometry, material and connection. A good agreement is achieved between experimental and numerical results in terms of shear strength-lateral displacement and failure modes.It is concluded that, for a fixed height-to-width aspect ratio, the shear strength of SWPs having different screws spacing varying from 50.4 mm up to 152.4 can be assessed by interpolation using this FE method. However, by interloping the shear strength from 4:1 to 1:1 height-to-width aspect ratio, the shear strength can be underestimated; hence, it is more economical for practicing engineers to use the shear strength assessed by this proposed FE method for 1.33:1 and 1:1 height-to-width aspect ratios. Moreover, the effect of the sheathing thickness having 0.46 mm is evaluated and proposed as it lacks in data provided by the code (i.e., AISI S400)
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