Oral abstracts of the 21st International AIDS Conference 18-22 July 2016, Durban, South Africa

The rate at which HIV-1 infected individuals progress to AIDS is highly variable and impacted by T cell immunity. CD8 T cell inhibitory molecules are up-regulated in HIV-1 infection and associate with immune dysfunction. We evaluated participants (n=122) recruited to the SPARTAC randomised clinical trial to determine whether CD8 T cell exhaustion markers PD-1, Lag-3 and Tim-3 were associated with immune activation and disease progression.Expression of PD-1, Tim-3, Lag-3 and CD38 on CD8 T cells from the closest pre-therapy time-point to seroconversion was measured by flow cytometry, and correlated with surrogate markers of HIV-1 disease (HIV-1 plasma viral load (pVL) and CD4 T cell count) and the trial endpoint (time to CD4 count <350 cells/μl or initiation of antiretroviral therapy). To explore the functional significance of these markers, co-expression of Eomes, T-bet and CD39 was assessed.Expression of PD-1 on CD8 and CD38 CD8 T cells correlated with pVL and CD4 count at baseline, and predicted time to the trial endpoint. Lag-3 expression was associated with pVL but not CD4 count. For all exhaustion markers, expression of CD38 on CD8 T cells increased the strength of associations. In Cox models, progression to the trial endpoint was most marked for PD-1/CD38 co-expressing cells, with evidence for a stronger effect within 12 weeks from confirmed diagnosis of PHI. The effect of PD-1 and Lag-3 expression on CD8 T cells retained statistical significance in Cox proportional hazards models including antiretroviral therapy and CD4 count, but not pVL as co-variants.Expression of ‘exhaustion’ or ‘immune checkpoint’ markers in early HIV-1 infection is associated with clinical progression and is impacted by immune activation and the duration of infection. New markers to identify exhausted T cells and novel interventions to reverse exhaustion may inform the development of novel immunotherapeutic approaches

Coral health in the Miocene of the Coral Triangle using X-Ray Micro-computed Tomography

Imperial Users onl

Transitional shock wave/boundary-layer interaction unsteadiness on a cone-flare in hypersonic flow

The causes of unsteadiness in hypersonic, axisymmetric, and transitional shock wave/boundary-layer interactions (SWBLIs) are investigated experimentally using a cone-flare model in the Oxford High Density Tunnel (HDT). The motivation of this research was to provide accurate measurements of the unsteadiness of transitional SWBLIs and provide a technique for studying such unsteadiness experimentally and numerically. Increasing the field’s understanding of these interactions will improve our ability to predict the large thermal and aerodynamic loading caused by transitional SWBLIs, i.e., SWBLIs in which the boundary layer is transitional. In turn, the design of the thermal protection systems and aerodynamic surfaces of hypersonic vehicles, which inevitably come in contact with SWBLIs in this flight regime, can be refined. Although the time-averaged characteristics of hypersonic SWBLIs have been studied in detail, transient measurements of transitional SWBLIs are rare in the literature. Similarly, recent studies at hypersonic Mach numbers have considered the boundary-layer and shear-layer disturbances which are amplified within the separation region of transitional SWBLIs. They found that a disturbance was amplified in the shear layers of these interactions which was distinct from the disturbance which dominates the transition process in axisymmetric, hypersonic boundary layers, the second-mode instability. However, there are gaps in the literature between the amplification of shear-layer instabilities, their breakdown to turbulent spots within the interaction region, and the resulting effects on the flowfields of these SWBLIs. The present thesis aims to bridge these gaps by linking the measurement of shear-layer instabilities, observations of turbulent spot formation, and movement of the separation region. A technique was also developed and implemented experimentally to confirm the link between turbulent spot formation and SWBLI unsteadiness. This technique can be used in future numerical work to reproduce such results without needing computationally-expensive simulations of the shear-layer transition process

Concept mapping : does it promote meaningful learning in science?

Concept mapping is a learning strategy based on constructivist theory that students leam by incorporating new knowledge into pre-existing frameworks, or constructs. This study attempts to determine whether on-going use of concept mapping by Biology 11 students facilitates meaningful learning. The study utilizes both qualitative (student interviews) and quantitative (statistical analysis of unit test scores) methodologies. For the quantitative analysis, the control and experimental groups consist of four classes of Biology 11 students where two blocks were exposed to concept mapping, while two were not (n=67; 33 concept mappers, 34 non-concept mappers). The findings are that although no statistically significant difference is found between the experimental and control groups, the statistical analysis suggests a trend of increasing test performance by concept mappers over non-concept mappers. The degree of difference increases the longer students have been exposed to concept mapping. Additionally, students provide insights into how concept mapping should be introduced, and shed light on common problems encountered while they learn the technique. Overall, students find concept mapping to be a valuable learning tool that most feel they will continue to utilize. Implications for teaching strategies are examined in light of students' experiences. A further study over a longer time frame could confirm the suggestion that with a longer exposure to concept mapping, a significant difference could be found between the experimental and control groups.Education, Faculty ofCurriculum and Pedagogy (EDCP), Department ofGraduat