Understanding experiences of potential harm among MSM (cis and trans) using HIV self-testing in the SELPHI randomised controlled trial in England and Wales: a mixed-methods study.

BACKGROUND: The potential of HIV self-testing (HIVST) to cause harm is a concern hindering widespread implementation. The aim of this paper is to understand the relationship between HIVST and harm in SELPHI (An HIV Self-testing Public Health Intervention), the largest randomised trial of HIVST in a high-income country to date. METHODS: 10 111 cis and trans men who have sex with men (MSM) recruited online (geolocation social/sexual networking apps, social media), aged 16+, reporting previous anal intercourse and resident in England or Wales were first randomised 60/40 to baseline HIVST (baseline testing, BT) or not (no baseline testing, nBT) (randomisation A). BT participants reporting negative baseline test, sexual risk at 3 months and interest in further HIVST were randomised to three-monthly HIVST (repeat testing, RT) or not (no repeat testing, nRT) (randomisation B). All received an exit survey collecting data on harms (to relationships, well-being, false results or being pressured/persuaded to test). Nine participants reporting harm were interviewed in-depth about their experiences in an exploratory substudy; qualitative data were analysed narratively. RESULTS: Baseline: predominantly cis MSM, 90% white, 88% gay, 47% university educated and 7% current/former pre-exposure prophylaxis (PrEP) users. Final survey response rate was: nBT=26% (1056/4062), BT=45% (1674/3741), nRT=41% (471/1147), RT=50% (581/1161).Harms were rare and reported by 4% (n=138/3691) in exit surveys, with an additional two false positive results captured in other study surveys. 1% reported harm to relationships and to well-being in BT, nRT and RT combined. In all arms combined, being pressured or persuaded to test was reported by 1% (n=54/3678) and false positive results in 0.7% (n=34/4665).Qualitative analysis revealed harms arose from the kit itself (technological harms), the intervention (intervention harms) or from the social context of the participant (socially emergent harms). Intervention and socially emergent harms did not reduce HIVST acceptability, whereas technological harms did. DISCUSSION: HIVST harms were rare but strategies to link individuals experiencing harms with psychosocial support should be considered for HIVST scale-up. TRIAL REGISTRATION NUMBER: ISRCTN20312003.

Pilot phase of an internet-based RCT of HIVST targeting MSM and transgender people in England and Wales: advertising strategies and acceptability of the intervention.

BACKGROUND: The SELPHI study (An HIV Self-Testing Public Health Intervention) is an online randomised controlled trial (RCT) of HIV self-testing (HIVST). The aim of this study was to assess the feasibility of recruiting UK men who have sex with men (cis and trans) and trans women who have sex with men to the SELPHI pilot, and the acceptability of the HIVST intervention used among those randomised to receive a kit. METHODS: A mixed-methods approach to assessing trial feasibility and intervention acceptability was taken, using quantitative data from advertising sources and RCT surveys alongside qualitative data from a nested sub-study. RESULTS: Online recruitment and intervention delivery was feasible. The recruitment strategy led to the registration of 1370 participants of whom 76% (1035) successfully enrolled and were randomised 60/40 to baseline testing vs no baseline testing. Advertising platforms performed variably. Reported HIVST kit use increased from 83% at two weeks to 96% at three months. Acceptability was very high across all quantitative measures. Participants described the instructions as easy to use, and the testing process as simple. The support structures in SELPHI were felt to be adequate. Described emotional responses to HIVST varied. CONCLUSIONS: Recruiting to a modest sized HIVST pilot RCT is feasible, and the recruitment, intervention and HIVST kit were acceptable. Research on support needs of individuals with reactive results is warranted.

Protocol, rationale and design of SELPHI: a randomised controlled trial assessing whether offering free HIV self-testing kits via the internet increases the rate of HIV diagnosis.

BACKGROUND: Among men who have sex with men (MSM) in the UK, an estimated 28% have never tested for HIV and only 27% of those at higher risk test at least every 6 months. HIV self-testing (HIVST), where the person takes their own blood/saliva sample and processes it themselves, offers the opportunity to remove many structural and social barriers to testing. Although several randomised controlled trials are assessing the impact of providing HIVST on rates of HIV testing, none are addressing whether this results in increased rates of HIV diagnoses that link to clinical care. Linking to care is the critical outcome because it is the only way to access antiretroviral treatment (ART). We describe here the design of a large, internet-based randomised controlled trial of HIVST, called SELPHI, which aims to inform this key question. METHODS/DESIGN: The SELPHI study, which is ongoing is promoted via social networking website and app advertising, and aims to enroll HIV negative men, trans men and trans women, aged over 16 years, who are living in England and Wales. Apart from the physical delivery of the test kits, all trial processes, including recruitment, take place online. In a two-stage randomisation, participants are first randomised (3:2) to receive a free baseline HIVST or no free baseline HIVST. At 3 months, participants allocated to receive a baseline HIVST (and meeting further eligibility criteria) are subsequently randomised (1:1) to receive the offer of regular (every 3 months) free HIVST, with testing reminders, versus no such offer. The primary outcome from both randomisations is a laboratory-confirmed HIV diagnosis, ascertained via linkage to a national HIV surveillance database. DISCUSSION: SELPHI will provide the first reliable evidence on whether offering free HIVST via the internet increases rates of confirmed HIV diagnoses and linkage to clinical care. The two randomisations reflect the dual objectives of detecting prevalent infections (possibly long-standing) and the more rapid diagnosis of incident HIV infections. It is anticipated that the results of SELPHI will inform future access to HIV self-testing provision in the UK. TRIAL REGISTRATION: DOI 10.1186/ISRCTN20312003 registered 24/10/2016.

Imaging Spatial Variations in the Dissipation and Transport of Thermal Energy within Individual Silicon Nanowires Using Ultrafast Microscopy.

Thermal management is an important consideration for most nanoelectronic devices, and an understanding of the thermal conductivity of individual device components is critical for the design of thermally efficient systems. However, it can be difficult to directly probe local changes in thermal conductivity within a nanoscale system. Here, we utilize the time-resolved and diffraction-limited imaging capabilities of ultrafast pump-probe microscopy to determine, in a contact-free configuration, the local thermal conductivity in individual Si nanowires (NWs). By suspending single NWs across microfabricated trenches in a quartz substrate, the properties of the same NW both on and off the substrate are directly compared. We find the substrate has no effect on the recombination lifetime or diffusion length of photogenerated charge carriers; however, it significantly impacts the thermal relaxation properties of the NW. In substrate-supported regions, thermal energy deposited into the lattice by the ultrafast laser pulse dissipates within ∼10 ns through thermal diffusion and coupling to the substrate. In suspended regions, the thermal energy persists for over 100 ns, and we directly image the time-resolved spatial motion of the thermal signal. Quantitative analysis of the transient images permits direct determination of the NW's local thermal conductivity, which we find to be a factor of ∼4 smaller than in bulk Si. Our results point to the strong potential of pump-probe microscopy to be used as an all-optical method to quantify the effects of localized environment and morphology on the thermal transport characteristics of individual nanostructured components.

Reversible strain-induced electron-hole recombination in silicon nanowires observed with femtosecond pump-probe microscopy.

Strain-induced changes to the electronic structure of nanoscale materials provide a promising avenue for expanding the optoelectronic functionality of semiconductor nanostructures in device applications. Here we use pump-probe microscopy with femtosecond temporal resolution and submicron spatial resolution to characterize charge-carrier recombination and transport dynamics in silicon nanowires (NWs) locally strained by bending deformation. The electron-hole recombination rate increases with strain for values above a threshold of ∼1% and, in highly strained (∼5%) regions of the NW, increases 6-fold. The changes in recombination rate are independent of NW diameter and reversible upon reduction of the applied strain, indicating the effect originates from alterations to the NW bulk electronic structure rather than introduction of defects. The results highlight the strong relationship between strain, electronic structure, and charge-carrier dynamics in low-dimensional semiconductor systems, and we anticipate the results will assist the development of strain-enabled optoelectronic devices with indirect-bandgap materials such as silicon.

Imaging charge separation and carrier recombination in nanowire p-i-n junctions using ultrafast microscopy.

Silicon nanowires incorporating p-type/n-type (p-n) junctions have been introduced as basic building blocks for future nanoscale electronic components. Controlling charge flow through these doped nanostructures is central to their function, yet our understanding of this process is inferred from measurements that average over entire structures or integrate over long times. Here, we have used femtosecond pump-probe microscopy to directly image the dynamics of photogenerated charge carriers in silicon nanowires encoded with p-n junctions along the growth axis. Initially, motion is dictated by carrier-carrier interactions, resulting in diffusive spreading of the neutral electron-hole cloud. Charge separation occurs at longer times as the carrier distribution reaches the edges of the depletion region, leading to a persistent electron population in the n-type region. Time-resolved visualization of the carrier dynamics yields clear, direct information on fundamental drift, diffusion, and recombination processes in these systems, providing a powerful tool for understanding and improving materials for nanotechnology.

Direct imaging of free carrier and trap carrier motion in silicon nanowires by spatially-separated femtosecond pump-probe microscopy.

We have developed a pump-probe microscope capable of exciting a single semiconductor nanostructure in one location and probing it in another with both high spatial and temporal resolution. Experiments performed on Si nanowires enable a direct visualization of the charge cloud produced by photoexcitation at a localized spot as it spreads along the nanowire axis. The time-resolved images show clear evidence of rapid diffusional spreading and recombination of the free carriers, which is consistent with ambipolar diffusion and a surface recombination velocity of ∼10(4) cm/s. The free carrier dynamics are followed by trap carrier migration on slower time scales.

Impact and acceptability of HIV self-testing for trans men and trans women: A mixed-methods subgroup analysis of the SELPHI randomised controlled trial and process evaluation in England and Wales.

BACKGROUND: Globally, trans people are disproportionately affected by HIV, but research on strategies to increase testing are limited. SELPHI is a randomised-controlled-trial (RCT) of 10,135 cis men, trans men, and trans women reporting lifetime anal intercourse with male partners (cis or trans), evaluating whether the offer of free HIV self-testing (HIVST) increases diagnosis. This subgroup analysis from the SELPHI RCT aims to describe key HIVST outcomes and HIVST acceptability for trans people. METHODS: SELPHI recruited using social networking and trans focused social media. Participants were randomised 60/40 to baseline HIVST (Biosure™) (BT) vs no baseline HIVST (nBT); and at 3-months (if completed the survey and reported recent CAI) 50/50 to 3-monthly HIVST (RT) vs no repeat HIVST (nRT). Outcomes were self-reported through online surveys. We conducted a qualitative study of semi-structured peer-led participant interviews (n = 20) exploring HIVST motivations and experiences. These were analysed using a framework approach. FINDINGS: SELPHI recruited and randomised 118 trans men and trans women (94 trans men, 24 trans women), of whom 20 (16 trans men, 4 trans women) underwent the second randomisation. Median age at baseline was 29 (IQR: 22, 37), 79% were white, 79% were UK born, 37% had degree level education, and 31% had never tested for HIV. 62% (n = 59) of trans men completed the 3-month survey, but survey completion by trans women in nBT was too low (1/11) for randomised comparison. In trans men HIV testing uptake by 3 months was significantly higher in BT (95% 36/38) vs nBT (29%, 6/21) (RR=3.32 (1.68, 6.55) p<0.001). Trans people randomised to RT reported 3 times higher rate of HIV testing compared to nRT during the two-year follow-up (IRR 3.66 (1.86, 8.01) p<0.0001). STI testing frequency (mean number of tests during each 13 week period/ 2-year follow-up) was not significantly different across interventions: RT (0.03) and nRT (0.01) (IRR=1.86 95%CI; 0.77, 5.15; p = 0.15). Social harms were rare. Acceptability was very high in BT: 97% (38/39) found instructions easy to understand, 97% (37/38) found the HIVST simple to use and 100% (39/39) reported good overall experience. In interviews, reported HIVST benefits included increased autonomy, privacy, convenience and avoidance of health care providers perceived to be discriminatory and services that increased dysphoria. Minor lancet and test processing issues were reported. INTERPRETATION: HIVST significantly increased testing uptake and frequency in trans men and trans people overall, although recruitment and retention of trans women was low. HIVST acceptability was high and indicates easy access to this novel technology may increase HIV testing access for this key population.

Exploring Mechanisms of Action: Using a Testing Typology to Understand Intervention Performance in an HIV Self-Testing RCT in England and Wales.

SELPHI involves two interventions: (A) It provides one HIV self-testing (HIVST) kit; (B) It offers 3-monthly repeat HIVST kits if participants report ongoing risk. A logic model underpinned by the Behaviour Change Wheel informed the design of the intervention. SELPHI recruited 10,135 cis-men and trans people in England and Wales, all reporting anal sex with a man. This paper explores how the interventions were experienced and the pathways to impact for different groups of trial participants. In-depth interviews with 37 cis-men who have sex with men (MSM) were used to inductively categorise participants based on sexual and HIV testing histories. Themes relating to intervention experiences and impacts were mapped onto SELPHI-hypothesised intermediate outcomes to consider intervention impacts. Three groups were identified: 'Inexperienced testers' engaged with SELPHI to overcome motivational and social and physical opportunity testing barriers. For 'pro self-testers', testing frequency was constrained by psychological and social barriers and lack of opportunity. 'Opportunistic adopters' engaged in HIVST for novelty and convenience. Perceived impacts for inexperienced testers were most closely aligned with the logic model, but for opportunistic adopters there was little evidence of impact. Distinctive groups were discernible with divergent intervention experiences. Using COM-B as a model for understanding behaviour change in relation to HIVST, our results indicate how HIVST interventions could be adapted to respond to different needs based on the target population's demographic and behavioural features.

Pump-probe microscopy: spatially resolved carrier dynamics in ZnO rods and the influence of optical cavity resonator modes.

Femtosecond pump-probe microscopy is used to investigate the charge recombination dynamics at different points within a single needle-shaped ZnO rod. Recombination in the tips of the rod occurs through an excitonic or electron-hole plasma state, taking place on a picosecond time scale. Photoexcitation in the larger diameter sections of the interior exhibit dramatically slower recombination that occurs primarily through defects sites, i.e., trap mediated recombination. Transient absorption imaging shows that the spatial variation in the dynamics is also influenced by the cavity resonances supported within the hexagonal cross section of the rod. Finite element simulations suggest that these optical resonator modes produce qualitatively different intensity patterns in the two different locations. Near the end of the rod, the intensity pattern has significant standing-wave character, which leads to the creation of photoexcited carriers in the core of the structure. The larger diameter regions, on the other hand, exhibit intensity distributions in which the whispering gallery (WG) mode character dominates. At these locations, the photoexcited carriers are produced in subsurface depletion zone, where the internal fields separate the electrons and holes and lead to a greater degree of trap recombination on longer time scales.