3,659 research outputs found
What are the essential components of HIV treatment and care services in low and middle-income countries: an overview by settings and levels of the health system?
OBJECTIVES: To review and summarize the essential components of HIV treatment and care services in low and middle-income countries (LMICs). METHODS: Literature review and reflection on programmatic experience. FINDINGS: There is increasing recognition that the essential 'package' of HIV care must include early identification of HIV-positive people in need of care, appropriate initial and continued counselling, assessment of HIV disease stage, treatment with HAART for those who need it, monitoring while on treatment for efficacy, adherence and side-effects, detection and management of other complications of HIV infection, provision of sexual and reproductive health services as well as careful record-keeping. The impressive scale-up of HIV treatment and care services has required decentralization of service provision linked to task-shifting. But the future holds even greater challenges, as the number of people in need of HIV care continues to rise at a time when many traditional donors and governments in the most-affected regions have reduced budgets. CONCLUSION: In the long-term, the increased demand for HIV-care services can only be satisfied through increased decentralisation to peripheral health units, with the role of each type of unit being appropriate to the human and material resources available to it.HIV-care services can also naturally integrate with the care of chronic noncommunicable diseases and with closely related services like mother and child health, and thus should promote a shift from vertical to integrated programming. Staff training and support around a set of evidence-based policies and guidelines and a reliable supply of essential medicines and supplies are further essential components for a successful programme
Heat flow in InAs/InP heterostructure nanowires
The transfer of heat between electrons and phonons plays a key role for
thermal management in future nanowire-based devices, but only a few
experimental measurements of electron-phonon (e-ph) coupling in nanowires are
available. Here, we combine experimental temperature measurements on an
InAs/InP heterostructure nanowire system with finite element modeling (FEM) to
extract information on heat flow mediated by e-ph coupling. We find that the
electron and phonon temperatures in our system are highly coupled even at
temperatures as low as 2 K. Additionally, we find evidence that the usual
power-law temperature dependence of electron-phonon coupling may not correctly
describe the coupling in nanowires and show that this result is consistent with
previous research on similar one-dimensional electron systems. We also compare
the strength of the observed e-ph coupling to a theoretical analysis of e-ph
interaction in InAs nanowires, which predicts a significantly weaker coupling
strength than observed experimentally.Comment: 9 pages, 6 figure
Non-equilibrium dynamics of a system with Quantum Frustration
Using flow equations, equilibrium and non-equilibrium dynamics of a two-level
system are investigated, which couples via non-commuting components to two
independent oscillator baths. In equilibrium the two-level energy splitting is
protected when the TLS is coupled symmetrically to both bath. A critical
asymmetry angle separates the localized from the delocalized phase.
On the other hand, real-time decoherence of a non-equilibrium initial state
is for a generic initial state faster for a coupling to two baths than for a
single bath.Comment: 22 pages, 9 figure
Characterization of hemodialysis membranes by inverse size exclusion chromatography
Inverse size exclusion chromatography (i-SEC) was used to characterize three different cellulosic hollow fiber hemodialysis membranes, i.e. low-flux cuprophan and hemophan and high-flux RC-HP400A. With the i-SEC technique the pore size distribution and porosity of a membrane can be determined and adsorption phenomena can be studied. The membranes showed clear differences in pore size and porosity, the high-flux RC-HP400A membrane has a larger pore size as well as a higher porosity. For all the membranes it was found that the elution curves were best described by a homoporous pore volume distribution. It appeared that the bound or non-freezing water in the membranes was at least partly accessible to solutes. The test molecules creatinine and vitamin B 12 both adsorbed to the cellulosic membranes. The adsorption behavior of creatinine was strongly dependent on the NaCl concentration present. The observations could be explained by assuming that cuprophan and RC-HP400A are negatively charged whereas hemophan is positively charged due to the modification with N,N-diethylaminoethyl ether. The net charge of the hemophan is smaller
Non-Gaussianity Consistency Relation for Multi-field Inflation
While detection of the "local form" bispectrum of primordial perturbations
would rule out all single-field inflation models, multi-field models would
still be allowed. We show that multi-field models described by the
formalism obey an inequality between and one of the local-form
{\it trispectrum} amplitudes, , such that with a possible logarithmic scale dependence,
provided that 2-loop terms are small. Detection of a violation of this
inequality would rule out most of multi-field models, challenging inflation as
a mechanism for generating the primoridal perturbations.Comment: 5 pages. Accepted for publication in Physical Review Letter
A quantum-dot heat engine operating close to the thermodynamic efficiency limits
Cyclical heat engines are a paradigm of classical thermodynamics, but are
impractical for miniaturization because they rely on moving parts. A more
recent concept is particle-exchange (PE) heat engines, which uses energy
filtering to control a thermally driven particle flow between two heat
reservoirs. As they do not require moving parts and can be realized in
solid-state materials, they are suitable for low-power applications and
miniaturization. It was predicted that PE engines could reach the same
thermodynamically ideal efficiency limits as those accessible to cyclical
engines, but this prediction has not been verified experimentally. Here, we
demonstrate a PE heat engine based on a quantum dot (QD) embedded into a
semiconductor nanowire. We directly measure the engine's steady-state electric
power output and combine it with the calculated electronic heat flow to
determine the electronic efficiency . We find that at the maximum power
conditions, is in agreement with the Curzon-Ahlborn efficiency and that
the overall maximum is in excess of 70 of the Carnot efficiency
while maintaining a finite power output. Our results demonstrate that
thermoelectric power conversion can, in principle, be achieved close to the
thermodynamic limits, with direct relevance for future hot-carrier
photovoltaics, on-chip coolers or energy harvesters for quantum technologies
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