Background: Many countries instituted lockdown rules as the COVID-19 pandemic progressed, however, the effects of COVID-19 on transportation safety vary widely across countries and regions. In several situations, it has been shown that although the COVID-19 closure has decreased average traffic flow, it has also led to an increase in speeding, which will indeed increase the severity of crashes and the number of fatalities and serious injuries.

Methods: At the local level, Generalized linear Mixed (GLM) modelling is used to look at how often road crashes changed in the Adelaide metropolitan area before and after the COVID-19 pandemic. The Geographically Weighted Generalized Linear Model (GWGLM) is also used to explore how the association between the number of crashes and the factors that explain them varies across census blocks. Using both no-spatial and spatial models, the effects of urban structure elements like land use mix, road network design, distance to CBD, and proximity to public transit on the frequency of crashes at the local level were studied.

Results: This research showed that lockdown orders led to a mild reduction (approximately 7%) in crash frequency. However, this decrease, which has occurred mostly during the first three months of the lockdown, has not systematically alleviated traffic safety risks in the Greater Adelaide Metropolitan Area. Crash hotspots shifted from areas adjacent to workplaces and education centres to green spaces and city fringes, while crash incidence periods switched from weekdays to weekends and winter to summer.

Implications: The outcomes of this research provided insights into the impact of shifting driving behaviour on safety during disorderly catastrophes such as COVID-19.

The health concerns of marginalized social groups are frequently overlooked. The PhD project employs a mixed-method approach encompassing an examination of the health-seeking behavior of female sex workers by exploring their health vulnerabilities, and the influencing factors in South-western region of Bangladesh. A systematic review on the study topic was conducted to identify knowledge gaps in this field first. The findings of the systematic review indicated concerns regarding sexual and reproductive health (SRH) issues, lack of access and awareness, social stigma, non-SRH matters, and drugs, violence and abuse. The data collection for this explanatory mixed-method study comprised a survey of 384 female sex workers and in-depth interviews with 20 participants for data triangulation purposes. The data were gathered from four categories of female sex workers i.e. those operating in brothels, hotels, home locations, and on the streets, from designated regions in the Khulna, Jessore, and Satkhira districts of southwestern Bangladesh. The quantitative component of the study, involving a survey, was conducted initially, collecting data exclusively from female sex workers. Subsequently, six key sector workers were interviewed alongside 14 female sex workers during the qualitative phase of the study. The findings were integrated to build discussion, implications and conclusion of the research in the final stage. Our integrated findings reveal that female sex workers exhibited diverse healthcare-seeking behaviors shaped by socioeconomic, familial, and societal influences in Bangladesh. We noted that around one-third of the participants favoured government services, while two-thirds (64.1%) reported of recent health check-ups. However, factors like higher income, joint family structures, and experiences of abuse were associated with lower service utilization (p < 0.001). Female sex workers shared experiences of encountering substantial obstacles such as stigma, harassment, insufficient infrastructure, and a scarcity of affordable specialized care, which calls for the pressing necessity for targeted interventions, health system accountability, and customized services to meet their physical, mental, and reproductive health need. Findings of this study will aid researchers, program planners, and policymakers in developing or enhancing strategic interventions for this marginalized group. The results have been shared with the target audience such as female sex workers, pertinent NGOs, research communities and local health professionals. Two qualitative papers have been published from the primary data, while the other papers are currently under review for publication. Additionally, the research findings have been presented in five national and international conferences.

Despite the widespread use of live attenuated vaccines, infectious laryngotracheitis (ILT) remains a persistent global threat to the poultry industry. Challenges in controlling this disease in Australia are partially related to the use of vaccines that provide imperfect immunity. The overarching aim of this thesis was to advance the understanding of ILTV vaccine-mediated protection in chickens. Specific objectives of this dissertation were to 1) optimise cryopreservation protocols for systemic and mucosal lymphoid tissues in chickens to enable reproducible immunophenotyping of cryopreserved samples by flow cytometry, 2) compare immune responses and protective efficacy induced by a ILTV vaccine when administered via eye drop (ED) or vent brush (VB) route to the cloaca, and 3) evaluate the durability of ILTV vaccine-mediated immunity in commercial laying hens.

To achieve the first objective, the study presented in Chapter Two evaluated the effect of cryopreservation on chicken lymphoid tissues, including peripheral blood lymphocytes (PBLs), spleen, Harderian gland, conjunctiva, caecal tonsil, and larynx-trachea. Fresh and cryopreserved samples were analysed by flow cytometry using major immune cell markers to assess cell viability and marker stability. For the second objective, outlined in Chapter Three, a challenge model was used to compare vaccine-mediated protection conferred by an ILTV vaccine, administered via ED or VB to 4-week-old layer chicks, against virulent Class 9 challenge 14 days after vaccination. The third objective, which is addressed in Chapter Four, evaluated the duration of clinical protection of commercial layer hens in three age groups (22, 49, and 62 weeks) that had received multiple doses of ILTV vaccine, in response to challenge with virulent class 9 ILTV.

The main findings of the studies in this thesis were: Objective 1) Cryopreservation of chicken lymphoid tissues showed that lymphocytes extracted from cryopreserved systemic tissues such as PBLs and spleen maintained acceptable cell viability and stable immune marker expression, demonstrating reliable preservation for later immunophenotyping. In contrast, lymphocyte extraction from cryopreserved mucosal tissues was inconsistent with loss of several cell markers, indicating the need for further optimisation. To ensure reliable immunophenotyping, fresh processing of mucosal tissues is recommended.

Objective 2) VB and ED vaccination provided equivalent clinical protection reflected by high protection indices against clinical signs after challenge (VB, 99%; ED, 90%) and pathological lesion scores in conjunctiva (VB, 83%; ED, 74%) and trachea (VB, 78%; ED, 69%). Both routes induced immune responses and gene expression profiles following challenge similar to vaccinated, non-challenged chickens, indicating comparable immunological efficacy. Findings indicated that vaccine-mediated protection was achieved through efficient recall and innate antiviral responses independent of vaccination route. Rapid activation of antiviral mechanisms, facilitated by the transient over-expression of MX1 and STAT1 in the absence of inflammatory markers of vaccinated and challenged chickens, suggests an efficient recall response with rapid viral clearance. The negative association of TLR3 expression with ILTV genome copies and clinical signs, with no increase in CD8A or CD4, further suggests that immunity relied on mucosal effector recall responses rather than T cell proliferation.

Objective 3) Substantial viral load was detected in 82% of hens on arrival. Surprisingly, a vaccine-like recombinant strain (class 7b) associated with recent outbreaks in Australia was detected in 41.7% of 49 weeks old (wo) and 25% of 62 wo hens. The silent circulation of field ILTV strains in commercial flocks is of epidemiological significance for the potential emergence of strains with increased virulence. Following challenge with class 9 ILTV, chickens showed no clinical signs, although 53.8%, 15.4%, and 0% of choanal swab samples tested positive in the 22, 49, and 62 wo groups respectively. Collectively, the results highlight the inability of the current Australian industry ILT vaccination protocols to prevent infection with field strains as early as 12 weeks post-vaccination.

This thesis advances understanding of avian immune responses and ILTV vaccine efficacy by revealing novel insights into mucosal immunity, identifying mucosal recall responses as a key mechanism of protection while demonstrating that existing vaccination protocols fail to prevent infection and circulation of field ILTV strains. It further illustrates that effective cryopreservation of mucosal tissues requires approaches beyond rapid freezing and warrants methodological refinement.

Recent and historical High Court of Australia jurisprudence has identified the ability to legislate in regard to the ‘defence’ head of power (under s 51(vi)) without significant restriction. This has allowed the executive a particular freedom to create statutory provisions that enable Defence a wide mandate to defend Australia and its national interests. While this projection of power provides an excellent foundation for external projection of forces, significant weaknesses in legislative development are identified internally, specifically surrounding the Defence Force Discipline Act 1982 (Cth) (DFDA) and its investigative powers. This thesis offers a critical analysis and legislative framework for reform of Pts V and VI of the DFDA and how best to meet not only Defence expectations of the investigative powers of discipline agencies (specifically the Australian Defence Force Military Police), but also those of the civilian and Defence communities they serve.

The first part of the study is a doctrinal analysis of the historical and current investigative powers of defence. It identifies how the legislation came from imperial acts to the current discipline system. The second part of the study analyses a peer discipline system, being that of the United Kingdom, and compares the investigative powers to Australia’s current discipline system. The study incorporates a second analysis of the powers of the Australian Federal Police (AFP), who provide investigative capacity to the Australian Capital Territory and Commonwealth. The systems of the UK Armed Forces and AFP were considered due to their contemporary legislative frameworks, as well as their legislative principles being easily adopted into the DFDA. Finally, the study concludes with a recommendation for contemporary legislative reform that can be considered for adoption into Pts V and VI of the DFDA. The study finds that the current DFDA investigative powers are ineffective in their present state to meet modern criminal investigative challenges, and that separate parts of the DFDA will be required to differentiate discipline officer investigations from Military Police investigations.