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The estimation of bed shear stress plays a pivotal role in understanding the complexities of flow dynamics in both natural and engineered channels. The commonly employed log law formula offers a mechanism to compute the bed shear stress in open channel flows. However, its applicability in flow transition remains relatively unexplored. In this thesis, an in-depth investigation into the behavior of the velocity profiles and bed shear stress during the transition from Rough to Smooth (RTS) and Smooth to Rough (STR) beds is undertaken. Experiments were conducted on smooth-to-rough (STR) and rough-to-smooth (RTS) transitions in an open channel flume under different composite water surface profiles. The velocity field was measured at the channel centerline using a Particle Image Velocimetry (PIV) system. The bed shear stress was determined from the measured velocity profile and water depth using several methods. The primary objective was to investigate the effects of bed roughness and water surface profile on bed shear stress in gradually varied flow. This study found that in gradually varied flow through a roughness transition the evolution of bed shear stress was related to both the water surface profile and bed roughness. In both RTS and STR transitions, the bed shear stress adjusted to the new bed condition almost immediately even though the velocity profile away from the bed was still evolving. Unlike external and close-conduit flows, however, the bed shear stress in free-surface flow is also affected by the local water depth, and thus the composite water surface profile created by the channel transition. The bed shear stress development closely followed the variation in local water depth, ultimately reaching equilibrium when the flow depth became uniform. It was also found that the choice of the displacement height of the mean velocity profile played an important role in determining the bed shear stress on a rough bed using the logarithmic law, and thus the development of bed shear stress in smooth-to-rough transition.

Gay and bisexual men (GBM) account for the majority of new HIV infections in Australia. Regular testing provides a pathway to prevention and treatment; however testing remains suboptimal in some GBM. One aim of this thesis was to understand in more detail the HIV testing practices among a retrospective cohort of 25,000 HIV-negative GBM attending 32 sexual health clinics (SHCs) in New South Wales (NSW) between 2009 and 2015. The analysis was conducted at a time when a range of clinic-based initiatives were introduced to promote HIV testing and showed a significant annual increase in HIV tests conducted (23–31%) and testing frequency (4–6%) in high-risk GBM, yet 54% did not meet the minimum recommended frequency. HIV self-testing, an appealing new technology, has the potential to improve testing uptake and frequency by reducing barriers to clinic attendance. At the commencement of this PhD, no trial evidence on effectiveness of self-testing in increasing HIV testing existed. To address these gaps, a randomised controlled trial (FORTH) was conducted; 362 high-risk GBM from NSW, Victoria and Queensland were randomised (1:1) to the intervention (free oral fluid self-tests) or standard care alone. A chapter in this thesis describes the rationale and design of the FORTH trial. At baseline, a survey was conducted among FORTH trial participants to examine the factors, including self-efficacy, associated with past HIV testing frequency and the future likelihood of self-testing. In multivariate analyses, self-efficacy was independently associated with both outcomes assessed: ≥3 HIV tests in the past year and the future likelihood of self-testing, suggesting improvement in self-efficacy and enhancement of knowledge and testing skills may facilitate frequent testing. The FORTH trial intention-to-treat results showed that HIV testing frequency increased two-fold in recently tested (past two years) GBM and nearly four-fold in non-recent testers (not tested in the past two years or never-tested) over 12 months (both significant), without a decline in facility-based HIV or STI testing frequency. Follow-up surveys conducted during the trial showed that HIV self-testing was acceptable and did not increase sexual risk behaviour. Together, these results highlight the improved targeting of HIV testing to high-risk GBM in NSW and support wider availability of HIV self-testing in Australia to improve testing uptake.

In the Near East the first five centuries after the Hijra (622-1106 A.D.) were dominated by the spread of Islam and the growth of Muslim states, and both developments were dependent on writing materials. This dissertation traces the history of writing materials and related crafts, craftsmen, and procedures during that period. From rough beginnings in the time of Muhammad (PBUH) through an efflorescence in the first century of ('c)Abbasid rule, the stationer's trade touched on a wide variety of technological developments and was involved in a similarly wide range of intellectual and administrative changes. The craft of wiraqah, 'stationery' in the broadest sense, was an institution which came to exercise significant political, social, and economic influence. Its initial growth, however, was due to the central role of the Qur'an in Islam, and it continued to be closely tied to spiritual and intellectual life in the prosperous ('c)Abbasid capital of Baghdad. The dissertation treats both the religious-intellectual and administrative aspects of the growing use of paper; it also touches on the writing materials used among the Arabs before the advent of paper, and the complex route by which that invention came from China via Samarq and into the world of Islam. Paper-manufacturing centers are surveyed, and the trade in stationery, the traders, and their trading places are treated, along with auxiliary crafts, notably copying and bookbinding. The processes of writing books and selling them are also explored, with attention to the public character of much composition in the medieval period. The dissertation draws largely on Arabic annalistic and belletristic sources, notably Ibn al-Nad(')im and Yaqut, modern papyrological, bibliographical, and codicological studies, though they are few in number, are also drawn on to supplement the literary sources.