818 research outputs found
Global equity gauge alliance: reflections on early experiences
The paper traces the evolution and working of the Global Equity Gauge Alliance (GEGA) and its efforts to promote health equity. GEGA places health equity squarely within a larger framework of social justice, linking findings on socioeconomic and health inequalities with differentials in power, wealth, and prestige in society. The Alliance's 11 country-level partners, called Equity Gauges, share a common action-based vision and framework called the Equity Gauge Strategy. An Equity Gauge seeks to reduce health inequities through three broad spheres of action, referred to as the 'pillars' of the Equity Gauge Strategy, which define a set of interconnected and overlapping actions. Measuring and tracking the inequalities and interpreting their ethical import are pursued through the Assessment and Monitoring pillar. This information provides an evidence base that can be used in strategic ways for influencing policy-makers through actions in the Advocacy pillar and for supporting grassroots groups and civil society through actions in the Community Empowerment pillar. The paper provides examples of strategies for promoting pro-equity policy and social change and reviews experiences and lessons, both in terms of technical success of interventions and in relation to the conceptual development and refinement of the Equity Gauge Strategy and overall direction of the Alliance. To become most effective in furthering health equity at both national and global levels, the Alliance must now reach out to and involve a wider range of organizations, groups, and actors at both national and international levels. Sustainability of this promising experiment depends, in part, on adequate resources but also on the ability to attract and develop talented leadership.0000-0001-7305-85940000-0003-3258-28370000-0003-1094-7655650742145
Localization transitions in non-Hermitian quantum mechanics
We study the localization transitions which arise in both one and two
dimensions when quantum mechanical particles described by a random
Schr\"odinger equation are subjected to a constant imaginary vector potential.
A path-integral formulation relates the transition to flux lines depinned from
columnar defects by a transverse magnetic field in superconductors. The theory
predicts that the transverse Meissner effect is accompanied by stretched
exponential relaxation of the field into the bulk and a diverging penetration
depth at the transition.Comment: 4 pages (latex) with 3 figures (epsf) embedded in the text using the
style file epsf.st
Vortex Pinning and Non-Hermitian Quantum Mechanics
A delocalization phenomenon is studied in a class of non-Hermitian random
quantum-mechanical problems. Delocalization arises in response to a
sufficiently large constant imaginary vector potential. The transition is
related to depinning of flux lines from extended defects in type-II
superconductors subject to a tilted external magnetic field. The physical
meaning of the complex eigenvalues and currents of the non-Hermitian system is
elucidated in terms of properties of tilted vortex lines. The singular behavior
of the penetration length describing stretched exponential screening of a
perpendicular magnetic field (transverse Meissner effect), the surface
transverse magnetization, and the trapping length are determined near the
flux-line depinning point.Comment: 2-column 27-pages RevTex file with 35 eps figure files embedded.
Minor errors amended. To be published in Phys. Rev.
A gp41 MPER-specific llama VHH requires a hydrophobic CDR3 for neutralization but not for antigen recognition
The membrane proximal external region (MPER) of the HIV-1 glycoprotein gp41 is targeted by the broadly neutralizing antibodies 2F5 and 4E10. To date, no immunization regimen in animals or humans has produced HIV-1 neutralizing MPER-specific antibodies. We immunized llamas with gp41-MPER proteoliposomes and selected a MPER-specific single chain antibody (VHH), 2H10, whose epitope overlaps with that of mAb 2F5. Bi-2H10, a bivalent form of 2H10, which displayed an approximately 20-fold increased affinity compared to the monovalent 2H10, neutralized various sensitive and resistant HIV-1 strains, as well as SHIV strains in TZM-bl cells. X-ray and NMR analyses combined with mutagenesis and modeling revealed that 2H10 recognizes its gp41 epitope in a helical conformation. Notably, tryptophan 100 at the tip of the long CDR3 is not required for gp41 interaction but essential for neutralization. Thus bi-2H10 is an anti-MPER antibody generated by immunization that requires hydrophobic CDR3 determinants in addition to epitope recognition for neutralization similar to the mode of neutralization employed by mAbs 2F5 and 4E10
Discovery and Identification of Dimethylsilanediol as a Contaminant in ISS Potable Water
In September 2010, analysis of ISS potable water samples was undertaken to determine the contaminant(s) responsible for a rise of total organic carbon (TOC) in the Water Processor Assembly (WPA) product water. As analysis of the routine target list of organic compounds did not reveal the contaminant, efforts to look for unknown compounds were initiated, resulting in discovery of an unknown peak in the gas chromatography/mass spectrometry (GC/MS) analysis for glycols. A mass spectrum of the contaminant was then generated by concentrating one of the samples and analyzing it by GC/MS in full-scan mode. Although a computer match of the compound identity could not be obtained with the instrument database, a search with a more up-to-date mass spectral library yielded a good match with dimethylsilanediol (DMSD). Inductively coupled plasma/mass spectrometry (ICP/MS) analyses showed abnormally high silicon levels in the samples, confirming that the unknown compound(s) contained silicon. DMSD was then synthesized to confirm the identification and provide a standard to develop a calibration curve. Further confirmation was provided by external direct analysis in real time time of flight (DART TOF) mass spectrometry. To routinely test for DMSD in the future, a quantitative method was needed. A preliminary GC/MS method was developed and archived samples from various locations on ISS were analyzed to determine the extent of the contamination and provide data for troubleshooting. This paper describes these events in more detail as well as problems encountered in routine GC/MS analyses and the subsequent development of high performance liquid chromatography and LC/MS/MS methods for measuring DMSD
A new perspective on matter coupling in 2d quantum gravity
We provide compelling evidence that a previously introduced model of
non-perturbative 2d Lorentzian quantum gravity exhibits (two-dimensional)
flat-space behaviour when coupled to Ising spins. The evidence comes from both
a high-temperature expansion and from Monte Carlo simulations of the combined
gravity-matter system. This weak-coupling behaviour lends further support to
the conclusion that the Lorentzian model is a genuine alternative to Liouville
quantum gravity in two dimensions, with a different, and much `smoother'
critical behaviour.Comment: 24 pages, 7 figures (postscript
Postcode Lotteries in Public Health - The NHS Health Checks Programme in North West London
<p>Abstract</p> <p>Background</p> <p>Postcode lotteries in health refer to differences in health care between different geographic areas. These have been previously associated with clinical services. However there has been little documentation of postcode lotteries relating to preventative health care services. This paper describes a postcode lottery effect in relation to the NHS Health Checks Programme (a national cardiovascular screening programme in England) in eight PCTs in the North West sector of London.</p> <p>Methods</p> <p>A descriptive cross-sectional analysis of the Health Checks Programme was carried out in eight PCTs in North West London using a structured data-collecting instrument.</p> <p>Results</p> <p>The analysis found variation in the implementation of the national Health Checks Programme in terms of: the screening approach taken; the allocated budget (which varied from £69,000 to £1.4 million per 100,000 eligible population); payment rates made to providers of Health Checks; tools used to identify and measure risk of cardiovascular disease and diabetes; monitoring and evaluation; and preventative services available following the health check.</p> <p>Conclusions</p> <p>This study identifies a postcode lottery effect related to a national public health programme. Although it is important to allow enough flexibility in the design of the Health Checks Programme so that it fits in with local factors, aspects of the programme may benefit from greater standardisation or stronger national guidance.</p
Discovery and Identification of Dimethylsilanediol as a Contaminant in ISS Potable Water
In September of 2010, analysis of ISS potable water samples was undertaken to determine the contaminant responsible for a rise in total organic carbon (TOC). As analysis of the routine target list of organic compounds did not reveal the contaminant, efforts to look for unknown compounds was initiated, resulting in an unknown peak being discovered in the gas chromatography/mass spectrometry (GC/MS) analysis for glycols. A mass spectrum of the contaminant was then generated by concentrating one of the samples by evaporation and analyzing by GC/MS in full-scan mode. Although a computer match of the compound s identity could not be obtained with the instrument s database, a search with a more up to date mass spectral library yielded a good match with dimethylsilanediol (DMSD). Inductively Coupled Plasma/Mass Spectrometry (ICP/MS) analyses showed abnormally high silicon levels in the samples, confirming that the unknown contained silicon. DMSD was then synthesized to confirm the identification and provide a standard to develop a calibration curve. Further confirmation was provided by external Direct Analysis in Real Time (DART) GC/MS analysis. A preliminary GC/MS method was then developed and archived samples from various locations on ISS were analyzed to determine the extent of the contamination and provide data for troubleshooting. This paper describes these events in more detail as well as problems encountered in routine GC/MS analyses and the subsequent development of high performance liquid chromatography and LC/MS/MS methods for quantitation of DMSD
How far will we need to go to reach HIV-infected people in rural South Africa?
Background: The South African Government has outlined detailed plans for antiretroviral (ART) rollout in KwaZulu-Natal Province, but has not created a plan to address treatment accessibility in rural areas in KwaZulu-Natal. Here, we calculate the distance that People Living With HIV/AIDS (PLWHA) in rural areas in KwaZulu-Natal would have to travel to receive ART. Specifically, we address the health policy question 'How far will we need to go to reach PLWHA in rural KwaZulu-Natal?'. Methods: We developed a model to quantify treatment accessibility in rural areas; the model incorporates heterogeneity in spatial location of HCFs and patient population. We defined treatment accessibility in terms of the number of PLWHA that have access to an HCF. We modeled the treatment-accessibility region (i.e. catchment area) around an HCF by using a two-dimensional function, and assumed that treatment accessibility decreases as distance from an HCF increases. Specifically, we used a distance-discounting measure of ART accessibility based upon a modified form of a two-dimensional gravity-type model. We calculated the effect on treatment accessibility of: (1) distance from an HCF, and (2) the number of HCFs. Results: In rural areas in KwaZulu-Natal even substantially increasing the size of a small catchment area (e.g. from 1 km to 20 km) around an HCF would have a negligible impact (~2%) on increasing treatment accessibility. The percentage of PLWHA who can receive ART in rural areas in this province could be as low as ~16%. Even if individuals were willing (and able) to travel 50 km to receive ART, only ~50% of those in need would be able to access treatment. Surprisingly, we show that increasing the number of available HCFs for ART distribution ~ threefold does not lead to a threefold increase in treatment accessibility in rural KwaZulu-Natal. Conclusion: Our results show that many PLWHA in rural KwaZulu-Natal are unlikely to have access to ART, and that the impact of an additional 37 HCFs on treatment accessibility in rural areas would be less substantial than might be expected. There is a great length to go before we will be able to reach many PLWHA in rural areas in South Africa, and specifically in KwaZulu-Natal.David P Wilson and Sally Blowe
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