Patient and provider perceptions of a peer-delivered intervention ('Khanya') to improve anti-retroviral adherence and substance use in South Africa: a mixed methods analysis

BACKGROUND: Despite a high prevalence of problematic substance use among people living with HIV in South Africa, there remains limited access to substance use services within the HIV care system. To address this gap, our team previously developed and adapted a six-session, peer-delivered problem-solving and behavioral activation-based intervention (Khanya) to improve HIV medication adherence and reduce substance use in Cape Town. This study evaluated patient and provider perspectives on the intervention to inform implementation and future adaptation. METHODS: Following intervention completion, we conducted semi-structured individual interviews with patients (n = 23) and providers (n = 9) to understand perspectives on the feasibility, acceptability, and appropriateness of Khanya and its implementation by a peer. Patients also quantitatively ranked the usefulness of individual intervention components (problem solving for medication adherence 'Life-Steps', behavioral activation, mindfulness training, and relapse prevention) at post-treatment and six months follow-up, which we triangulated with qualitative feedback to examine convergence and divergence across methods. RESULTS: Patients and providers reported high overall acceptability, feasibility, and appropriateness of Khanya, although there were several feasibility challenges. Mindfulness and Life-Steps were identified as particularly acceptable, feasible, and appropriate components by patients across methods, whereas relapse prevention strategies were less salient. Behavioral activation results were less consistent across methods. CONCLUSIONS: Findings underscore the importance of examining patients' perspectives on specific intervention components within intervention packages. While mindfulness training and peer delivery models were positively perceived by consumers, they are rarely used within task-shared behavioral interventions in low- and middle-income countries

Habitable Zones in the Universe

Habitability varies dramatically with location and time in the universe. This was recognized centuries ago, but it was only in the last few decades that astronomers began to systematize the study of habitability. The introduction of the concept of the habitable zone was key to progress in this area. The habitable zone concept was first applied to the space around a star, now called the Circumstellar Habitable Zone. Recently, other, vastly broader, habitable zones have been proposed. We review the historical development of the concept of habitable zones and the present state of the research. We also suggest ways to make progress on each of the habitable zones and to unify them into a single concept encompassing the entire universe.Comment: 71 pages, 3 figures, 1 table; to be published in Origins of Life and Evolution of Biospheres; table slightly revise

The dynamics of multiscale, multiphysics faults: Part I - The long-term behaviour of the lithosphere

Here we used a physics-based geomechanics approach to show that the long-term strength of the lithosphere is controlled by multiple steady states that arise as a function of significant material weakening at and above a critical value of local dissipation. Ultimately, the long-term strength of the lithosphere is governed by whether it can reach this critical value to form plate boundaries and intraplate lithosphere scale fault zones. We identify two different regimes: (1) post-yield steady state creep strength, (2) post-yield localization strength. Accordingly, in regime (1) the plate tectonic loading is insufficiently large to breach the critical local dissipation needed to reduce the overall long-term strength of the lithosphere. This regime is described in classical thermal-mechanical geodynamic models based on material values derived from laboratory experiments. The approach leads to the “jelly-sandwich” model of long term lithosphere strength. The constitutive models predict that the strongest portion of the lithosphere is the upper mantle followed by the upper crust; both can support mountain ranges for long geological times and lead to large effective elastic flexural rigidities. For regime (2) we identify two possible responses. One in which the plate strength is reduced by chemical and thermal feedback processes. And the other one where crystal plastic deformation causes micron scale Fick diffusion controlled micro-shears, that in turn release fluid to feed millimetre-metre scale hydraulic subshears (Darcy diffusion controlled) to finally drive kilometre scale Fourier diffusion controlled plate boundary shears. Under these special conditions the mantle can become extremely weak such as in the “crème brûlée” model. We conclude that both models have their validity. They reveal two different end members of dynamic thermodynamic feedbacks at different critical dynamic loadings and chemical composition

Shear heating in creeping faults changes the onset of convection

The interaction between mechanical deformation of creeping faults and fluid flow in porous media has an important influence on the heat and mass transfer processes in Earth sciences. Creeping faults can act as heat sources due to the effect of shear heating and as such could be expected to alter the conditions for hydrothermal convection. In this work, we provide a finite element-based numerical framework developed to resolve the problem of heat and mass transfer in the presence of creeping faults. This framework extends the analytical approach of the linear stability analysis (LSA) frequently used to determine the bifurcation criterion for onset of convection, allowing us to study compressible cases with the option of complex geometry and/or material inhomogeneities. We demonstrate the impact of creeping faults on the onset of convection and show that shear heating-expressed through its dimensionless group the Gruntfest number Gr-has exponential influence on the critical value of the Lewis number Le (inversely proportional to the Rayleigh number Ra) required for convection: Lec ~ Lec0 eGr. In this expression, Lec0 is the critical value of Le in the absence of shear heating. This exponential scaling shows that shear heating increases the critical Lewis number and triggers hydrothermal convection at lower permeability than in situations without it. We also show that the effect of shear heating in a fault significantly alters the pattern of convection in and around the fault zone