Predictors of linkage to care following community-based HIV counseling and testing in rural Kenya

Despite innovations in HIV counseling and testing (HCT), important gaps remain in understanding linkage to care. We followed a cohort diagnosed with HIV through a community-based HCT campaign that trained persons living with HIV/AIDS (PLHA) as navigators. Individual, interpersonal, and institutional predictors of linkage were assessed using survival analysis of self-reported time to enrollment. Of 483 persons consenting to follow-up, 305 (63.2%) enrolled in HIV care within 3 months. Proportions linking to care were similar across sexes, barring a sub-sample of men aged 18–25 years who were highly unlikely to enroll. Men were more likely to enroll if they had disclosed to their spouse, and women if they had disclosed to family. Women who anticipated violence or relationship breakup were less likely to link to care. Enrolment rates were significantly higher among participants receiving a PLHA visit, suggesting that a navigator approach may improve linkage from community-based HCT campaigns.Vestergaard Frandse

Progress towards high-performance, steady-state spherical torus

Research on the spherical torus (or spherical tokamak) (ST) is being pursued to explore the scientific benefits of modifying the field line structue fro that in more moderate aspect ratio devices. The ST experiments are being conducted in various US research facilities. The area of power and particle handling is expected to be challenging because of the higher power density expected in the ST relative to that in conventional aspect-ratio tokamaks

Recent D-T results on TFTR

Routine tritium operation in TFTR has permitted investigations of alpha particle physics in parameter ranges resembling those of a reactor core. ICRF wave physics in a DT plasma and the influence of isotopic mass on supershot confinement have also been studied. Continued progress has been made in optimizing fusion power production in TFTR, using extended machine capability and Li wall conditioning. Performance is currently limited by MHD stability. A new reversed magnetic shear regime is being investigated with reduced core transport and a higher predicted stability limit

Relating the L-H power threshold scaling to edge turbulence dynamics

Understanding the physics of the L-H transition power threshold scaling dependencies on toroidal field and density is critical to operating and optimizing the performance of ITER. Measurements of long-wavelength (k ρI < 1) turbulent eddy dynamics, characteristics, flows, and flow shear in the near edge region of DIIID plasmas have been obtained during an ion gyroradius scan (varying toroidal field and current) and density scan in a favourable geometry (ion ∇B drifts towards the X-point), in order to determine the underlying mechanisms that influence the macroscopic L-H power threshold scaling relations. It is found that the normalized integrated long wavelength density fluctuation amplitudes (ñ/n) in the pedestal increases with ρ* approaching the L-H transition. The turbulence poloidal flow spectrum evolves from geodesic acoustic mode dominant at lower power to low-frequency zonal flow (LFZF) dominant near the L-H transition, and the effective shearing rate correspondingly increases. An inferred Reynolds stress, , from BES velocimetry (inferring velocity field from imaging) measurements is found to significantly increase near the L-H transition. At lower electron density, a clear increase of the LFZF is observed prior to the L-H transition, which is not evident at higher density. Taken together, these results are qualitatively consistent with the electron density and toroidal field scaling of the L-H transition power threshold. © 2013 IAEA, Vienna

Spectroscopy of Divertor Plasmas

The requirements for divertor spectroscopy are treated with respect to instrumentation and observations on present machines. Emphasis is placed on quantitative measurements.of impurity concentrations from the interpretation of spectral line intensities. The possible influence of non-Maxwellian electron distributions on spectral line excitation in the divertor is discussed. Finally the use of spectroscopy for determining plasma temperature, density, and flows is examined

Characteristics of low-q disruptions in PBX

At low q (2.3 ≤ q ≤ 4.5), in the Princeton Beta Experiment, the discharges are limited by a hard disruption following the growth and sawtooth-like 'crash' of a ≤25 kHz precursor oscillation. The disruption, which occurs even in discharges with ⟨ ⟨ well below the first stability regime boundary (2.5 μ I aB ), follows the crash of this precursor mode either immediately or with a delay of several milliseconds, with the immediate disruptions primarily occurring in the discharges with ⟨ ⟩ close to the first regime limit. The highest ⟨ ⟩ discharges also exhibit the fastest growth times and the highest level of edge MHD activity. Associated with the precursor mode crash is a loss of up to 30% of the plasma energy; thus, for non-zero delay shots, it is the crash and not the actual disruption that is the ⟨ ⟩ limiting process. The delay period is interpreted as a period during which a locked mode, consisting of several toroidal components of comparable amplitude, grows. Because of the energy loss associated with the crash, the plasma goes vertically unstable during the delay period. The results of this study indicate that even within the relatively narrow low-q operating space, there is a continuum in the characteristics of the low-q^ disruptions with a primary dependence on the value of ⟨ ⟩. While the ideal external kink instability may give rise to the growing oscillations that lead up to the ultimate disruption, the instabilities are weighted towards the edge only at the lowest q (≤3) and highest ⟨ ⟩. The results of this study indicate that effects outside the scope of ideal MHD theory may play a significant role in low-q disruptions. © 1988 IOP Publishing Ltd. ψ ψ t 0 p t t t t ψ t ψ t

Initial results from the scoop limiter experiment in PDX

A particle scoop limiter with a graphite face backed by a 50 liter volume for collecting particles was used in PDX. Experiments were performed to test its particle control and power handling capabilities with up to 5 MW of D° power injected into D+ plasmas. Line average plasma densities of up to 8 × 1013 cm-3 and currents up to 450 kA were obtained. Plasma densities in the scoop channels greater than 2 × 1013 cm-3 and neutral densities in the scoop volume greater than 5 × 1014 cm-3 were observed. There is evidence that recycling may have occurred in the scoop channels for several discharges with large line-averaged plasma density. At beam powers up to 2.5 MW, energy confinement times above 40 ms were deduced from magnetics measurements and from transport analysis. Pressures in the vacuum vessel were in the 10 -5 Torr range, and recycling source neutral densities in the central plasma were low. © 1984

High-temperature plasmas in a tokamak fusion test reactor.

Neutral-beam heating of plasmas in the Tokamak Fusion Test Reactor at low preinjection densities [ne(0)1019 m-3] were characterized by Te(0)=6.5 keV, Ti(0)=20 keV, ne(0)=7×1019 m-3, E=170 msec, theta=2, and a d(d,n)3He neutron emission rate of 1016 sec-1. The ion temperature and the deuterium-fusion neutron yields were significantly higher than for previous tokamak experiments. The low initial densities were achieved by operation of the Tokamak Fusion Test Reactor with low plasma currents (1 MA) and by extensive limiter conditioning. © 1987 The American Physical Society