Publications

The effect of nitrogen doping on the structural, electronic and optical properties of hexagonal and cubic Ge₂Sb₂Te₅ (GST) has been investigated from first principles. The nitrogen content was set to 10 at.% and 25 at.%, in which it was found that the hexagonal phase becomes more stable, whereas the cubic phase becomes more unstable with increasing nitrogen content. A difference in optical reflectivity of about 8% was calculated for pure hexagonal and cubic phases. Pure GST was found to possess a higher reflectivity contrast in the infrared spectral range, whereas doped GST had a higher reflectivity contrast, which increased with rising nitrogen content, in the visible and ultraviolet spectral range. The optical conductivity was found to fall with increasing nitrogen content, in agreement with experiment and other theoretical studies.

Research suggests a burden of HIV among street-connected youth (SCY) in Kenya. We piloted the use of peer navigators (PNs), individuals of mixed HIV serostatus and with direct experience of being street-connected, to link SCY to HIV testing and care. From January 2015 to October 2017, PNs engaged 781 SCY (585 male, 196 female), median age 16 (IQR 13–20). At initial encounter, 52 (6.6{%}) were known HIV-positive and 647 (88.8{%}) agreed to HIV testing. Overall, 63/781 (8.1{%}) SCY engaged in this program were HIV-positive; 4.6{%} males and 18.4{%} females (p < 0.001). Of those HIV-positive, 48 (82.8{%}) initiated ART. As of October 2017, 35 (60.3{%}) of the HIV-positive SCY were alive and in care. The pilot suggests that PNs were successful in promoting HIV testing, linkage to care and ART initiation. More research is needed to evaluate how to improve ART adherence, viral suppression and retention in care in this population.