2,535 research outputs found
Impact and Cost-Effectiveness of Point-Of-Care CD4 Testing on the HIV Epidemic in South Africa.
Rapid diagnostic tools have been shown to improve linkage of patients to care. In the context of infectious diseases, assessing the impact and cost-effectiveness of such tools at the population level, accounting for both direct and indirect effects, is key to informing adoption of these tools. Point-of-care (POC) CD4 testing has been shown to be highly effective in increasing the proportion of HIV positive patients who initiate ART. We assess the impact and cost-effectiveness of introducing POC CD4 testing at the population level in South Africa in a range of care contexts, using a dynamic compartmental model of HIV transmission, calibrated to the South African HIV epidemic. We performed a meta-analysis to quantify the differences between POC and laboratory CD4 testing on the proportion linking to care following CD4 testing. Cumulative infections averted and incremental cost-effectiveness ratios (ICERs) were estimated over one and three years. We estimated that POC CD4 testing introduced in the current South African care context can prevent 1.7% (95% CI: 0.4% - 4.3%) of new HIV infections over 1 year. In that context, POC CD4 testing was cost-effective 99.8% of the time after 1 year with a median estimated ICER of US$4,468/DALY averted. In healthcare contexts with expanded HIV testing and improved retention in care, POC CD4 testing only became cost-effective after 3 years. The results were similar when, in addition, ART was offered irrespective of CD4 count, and CD4 testing was used for clinical assessment. Our findings suggest that even if ART is expanded to all HIV positive individuals and HIV testing efforts are increased in the near future, POC CD4 testing is a cost-effective tool, even within a short time horizon. Our study also illustrates the importance of evaluating the potential impact of such diagnostic technologies at the population level, so that indirect benefits and costs can be incorporated into estimations of cost-effectiveness
Nielsen-Olesen strings in Supersymmetric models
We investigate the behaviour of a model with two oppositely charged scalar
fields. In the Bogomol'nyi limit this may be seen as the scalar sector of N=1
supersymmetric QED, and it has been shown that cosmic strings form. We examine
numerically the model out of the Bogomol'nyi limit, and show that this remains
the case. We then add supersymmetry-breaking mass terms to the supersymmetric
model, and show that strings still survive.
Finally we consider the extension to N=2 supersymmetry with
supersymmetry-breaking mass terms, and show that this leads to the formation of
stable cosmic strings, unlike in the unbroken case.Comment: 7 pages, 2 figues, uses revtex4; minor typos corrected; references
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Primary goals, information-giving and men\u27s understanding: A qualitative study of Australian and UK doctors\u27 varied communication about PSA screening
Objectives: (1) To characterise variation in general practitionersâ (GPsâ) accounts of communicating with men about prostate cancer screening using the prostate-specific antigen (PSA) test, (2) to characterise GPsâ reasons for communicating as they do and (3) to explain why and under what conditions GP communication approaches vary.
Study design and setting: A grounded theory study. We interviewed 69 GPs consulting in primary care practices in Australia (n=40) and the UK (n=29).
Results: GPs explained their communication practices in relation to their primary goals. In Australia, three different communication goals were reported: to encourage asymptomatic men to either have a PSA test, or not test, or alternatively, to support men to make their own decision. As well as having different primary goals, GPs aimed to provide different information (from comprehensive to strongly filtered) and to support men to develop different kinds of understanding, from population-level to âgistâ understanding. Taking into account these three dimensions (goals, information, understanding) and building on Entwistle et alâs Consider an Offer framework, we derived four overarching approaches to communication: Be screened, Do not be screened, Analyse and choose, and As you wish. We also describe ways in which situational and relational factors influenced GPsâ preferred communication approach.
Conclusion: GPsâ reported approach to communicating about prostate cancer screening varies according to three dimensionsâtheir primary goal, information provision preference and understanding soughtâand in response to specific practice situations. If GP communication about PSA screening is to become more standardized in Australia, it is likely that each of these dimensions will require attention in policy and practice support interventions
Critical phenomena in a highly constrained classical spin system: Neel ordering from the Coulomb phase
Many classical, geometrically frustrated antiferromagnets have
macroscopically degenerate ground states. In a class of three-dimensional
systems, the set of degenerate ground states has power-law correlations and is
an example of a Coulomb phase. We investigate Neel ordering from such a Coulomb
phase, induced by weak additional interactions that lift the degeneracy. We
show that the critical point belongs to a universality class that is different
from the one for the equivalent transition out of the paramagnetic phase, and
that it is characterised by effective long-range interactions; alternatively,
ordering may be discontinuous. We suggest that a transition of this type may be
realised by applying uniaxial stress to a pyrochlore antiferromagnet.Comment: 4 pages, 3 figure
Fermion zero modes in N=2 supervortices
We study the fermionic zero modes of BPS semilocal magnetic vortices in N=2
supersymmetric QED with a Fayet-Iliopoulos term and two matter hypermultiplets
of opposite charge. There is a one-parameter family of vortices with
arbitrarily wide magnetic cores. Contrary to the situation in pure
Nielsen-Olesen vortices, new zero modes are found which get their masses from
Yukawa couplings to scalar fields that do not wind and are non-zero at the
core. We clarify the relation between fermion mass and zero modes. The new zero
modes have opposite chiralities and therefore do not affect the net counting
(left minus right) of zero modes coming from index theorems but manage to evade
other index theorems in the literature that count the total number (left plus
right) of zero modes in simpler systems.Comment: 9 pages, 1 figure. Uses Revtex4. Revised version includes discussion
about the back-reaction of the fermions on the background vortex. Version to
be published in Phys. Rev.
Infrared identification of IGR J09026-4812 as a Seyfert 1 galaxy
IGR J09026-4812 was discovered by INTEGRAL in 2006 as a new hard X-ray
source. Thereafter, an observation with Chandra pinpointed a single X-ray
source within the ISGRI error circle, showing a hard spectrum, and improving
its high-energy localisation to a subarcsecond accuracy. Thus, the X-ray source
was associated to the infrared counterpart 2MASS J09023731-4813339 whose JHKs
photometry indicated a highly reddened source. The high-energy properties and
the counterpart photometry suggested a high-mass X-ray binary with a main
sequence companion star located 6.3-8.1 kpc away and with a 0.3-10 keV
luminosity of 8e34 erg/s. New optical and infrared observations were needed to
confirm the counterpart and to reveal the nature of IGR J09026-4812. We
performed optical and near infrared observations on the counterpart 2MASS
J09023731-4813339 with the ESO/NTT telescope on March 2007. We achieved
photometry and spectroscopy in near infrared wavelengths and photometry in
optical wavelengths. The accurate astrometry at both optical and near infrared
wavelengths confirmed 2MASS J09023731-4813339 to be the counterpart of IGR
J09026-4812. However, the near infrared images show that the source is
extended, thus excluding any Galactic compact source possibility. The source
spectrum shows three main emission lines identified as the HeI lambda 1.0830
micron line, and the HI Pa_beta and Pa_alpha lines, typical in galaxies with an
active galactic nucleus. The broadness of these lines reached values as large
as 4000 km/s pointing towards a type 1 Seyfert galaxy. The redshift of the
source is z=0.0391(4). Thus, the near infrared photometry and spectroscopy
allowed us to classify IGR J09026-4812 as a Seyfert galaxy of type 1.Comment: 4 pages, 3 figures, Astronomy and Astrophysics in pres
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