637 research outputs found

    To DGC or not to DGC: oxygen guarding in the termite Zootermopsis nevadensis (Isoptera: Termopsidae)

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    The ability of some insects to engage in complex orchestrations of tracheal gas exchange has been well demonstrated, but its evolutionary origin remains obscure. According to a recently proposed hypothesis, insects may employ spiracular control of gas exchange to guard tissues against long-term oxidative damage by using the discontinuous gas-exchange cycle (DGC) to limit internal oxygen partial pressure (P_(O_2)). This manuscript describes a different approach to oxygen guarding in the lower termite Zootermopsis nevadensis. These insects do not display a DGC but respond to elevated oxygen concentrations by restricting spiracular area, resulting in a transient decline in CO_2 emission. High internal CO_2 concentrations are then maintained; restoring normoxia results in a transient reciprocal increase in CO_2 emission caused by release of excess endotracheal CO_2. These changes in spiracular area reflect active guarding of low internal O_2 concentrations and demonstrate that regulation of endotracheal hypoxia takes physiological priority over prevention of CO_2 build-up. This adaptation may reflect the need to protect oxygen-sensitive symbionts (or, gut bug guarding). Termites may eschew the DGC because periodic flushing of the tracheal system with air may harm the obligate anaerobes upon which the lower termites depend for survival on their native diet of chewed wood

    A Multi-Faceted Multi-Stakeholder Approach for Increased Visibility of ETDs in Zambia

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    The University of Zambia has had a functional Institutional Repository (IR) since 2012. However, while Electronic Theses and Dissertations (ETD) are routinely deposited into the IR, the ingestion is not timely, with significantly large time gaps existing between ETD submission dates and ETD IR ingestion dates. We propose a multi-faceted approach that is aimed at providing a potentially viable solution to the problems through the use of effective workflows and automatic classification of IR objects. Preliminary results demonstrate the potential of the proposed approach is feasible. It is anticipated that the proposed approach will facilitate the implementation of a National ETD portal for storing up-to-date and consistent metadata records from Higher Education Institutions across Zambia

    Metabolic rate scaling, ventilation patterns and respiratory water loss in red wood ants: activity drives ventilation changes, metabolic rate drives water loss

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    Metabolic rate and its relationship with body size is a fundamental determinant of many life history traits and potentially of organismal fitness. Alongside various environmental and physiological factors, the metabolic rate of insects is linked to distinct ventilation patterns. Despite significant attention, however, the precise role of these ventilation patterns remains uncertain. Here, we determined the allometric scaling of metabolic rate and respiratory water loss in the red wood ant, as well as assessing the effect of movement upon metabolic rate and ventilation pattern. Metabolic rate and respiratory water loss are both negatively allometric. We observed both continuous and cyclic ventilation associated with relatively higher and lower metabolic rates, respectively. In wood ants, however, movement not metabolic rate is the primary determinant of which ventilation pattern is performed. Conversely, metabolic rate not ventilation pattern is the primary determinant of respiratory water loss. Our statistical models produced a range of relatively shallow intraspecific scaling exponents between 0.40 and 0.59, emphasising the dependency upon model structure. Previous investigations have revealed substantial variation in morphological allometry among wood ant workers from different nests within a population. Metabolic rate scaling does not exhibit the same variability, suggesting that these two forms of scaling respond to environmental factors in different ways

    Oxygen Reperfusion Damage in an Insect

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    The deleterious effects of anoxia followed by reperfusion with oxygen in higher animals including mammals are well known. A convenient and genetically well characterized small-animal model that exhibits reproducible, quantifiable oxygen reperfusion damage is currently lacking. Here we describe the dynamics of whole-organism metabolic recovery from anoxia in an insect, Drosophila melanogaster, and report that damage caused by oxygen reperfusion can be quantified in a novel but straightforward way. We monitored CO2 emission (an index of mitochondrial activity) and water vapor output (an index of neuromuscular control of the spiracles, which are valves between the outside air and the insect's tracheal system) during entry into, and recovery from, rapid-onset anoxia exposure with durations ranging from 7.5 to 120 minutes. Anoxia caused a brief peak of CO2 output followed by knock-out. Mitochondrial respiration ceased and the spiracle constrictor muscles relaxed, but then re-contracted, presumably powered by anaerobic processes. Reperfusion to sustained normoxia caused a bimodal re-activation of mitochondrial respiration, and in the case of the spiracle constrictor muscles, slow inactivation followed by re-activation. After long anoxia durations, both the bimodality of mitochondrial reactivation and the recovery of spiracular control were impaired. Repeated reperfusion followed by episodes of anoxia depressed mitochondrial respiratory flux rates and damaged the integrity of the spiracular control system in a dose-dependent fashion. This is the first time that physiological evidence of oxygen reperfusion damage has been described in an insect or any invertebrate. We suggest that some of the traditional approaches of insect respiratory biology, such as quantifying respiratory water loss, may facilitate using D. melanogaster as a convenient, well-characterized experimental model for studying the underlying biology and mechanisms of ischemia and reperfusion damage and its possible mitigation

    Incarcerated aboriginal women's experiences of accessing healthcare and the limitations of the 'equal treatment' principle.

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    BACKGROUND:Colonization continues in Australia, sustained through institutional and systemic racism. Targeted discrimination and intergenerational trauma have undermined the health and wellbeing of Australia's Aboriginal and Torres Strait Islander population, leading to significantly poorer health status, social impoverishment and inequity resulting in the over-representation of Aboriginal people in Australian prisons. Despite adoption of the 'equal treatment' principle, on entering prison in Australia entitlements to the national universal healthcare system are revoked and Aboriginal people lose access to health services modelled on Aboriginal concepts of culturally safe healthcare available in the community. Incarcerated Aboriginal women experience poorer health outcomes than incarcerated non-Indigenous women and Aboriginal men, yet little is known about their experiences of accessing healthcare. We report the findings of the largest qualitative study with incarcerated Aboriginal women in New South Wales (NSW) Australia in over 15 years. METHODS:We employed a decolonizing research methodology, 'community collaborative participatory action research', involving consultation with Aboriginal communities prior to the study and establishment of a Project Advisory Group (PAG) of community expert Aboriginal women to guide the project. Forty-three semi-structured interviews were conducted in 2013 with Aboriginal women in urban and regional prisons in NSW. We applied a grounded theory approach for the data analysis with guidance from the PAG. RESULTS:Whilst Aboriginal women reported positive and negative experiences of prison healthcare, the custodial system created numerous barriers to accessing healthcare. Aboriginal women experienced institutional racism and discrimination in the form of not being listened to, stereotyping, and inequitable healthcare compared with non-Indigenous women in prison and the community. CONCLUSIONS:'Equal treatment' is an inappropriate strategy for providing equitable healthcare, which is required because incarcerated Aboriginal women experience significantly poorer health. Taking a decolonizing approach, we unpack and demonstrate the systems level changes needed to make health and justice agencies culturally relevant and safe. This requires further acknowledgment of the oppressive transgenerational effects of ongoing colonial policy, a true embracing of diversity of worldviews, and critically the integration of Aboriginal concepts of health at all organizational levels to uphold Aboriginal women's rights to culturally safe healthcare in prison and the community

    Investigating the Impact of Organised Technology-driven Orchestration on Teaching

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    Orchestration of learning involves the real-time management of activities performed by educators in learning environments, with a particular focus on the effective use of technology. While different educational settings present unique problems, the common challenges have been noted to primarily be as a result of multiple heterogeneous activities and their associated intrinsic and extrinsic constraints. In addition to these challenges, this thesis argues that the complexities of orchestration are further amplified due to the ad hoc nature of the approaches and techniques used to orchestrate learning activities. The thesis proposes a streamlined approach to technology-driven orchestration of learning, in order to address these challenges and complexities. Specifically, the thesis proposes an organised approach that focuses on three core aspects of orchestration: activity management, resource management and sequencing of learning activities. Orchestration was comprehensively explored in order to identify the core aspects essential for streamlining technology-driven orchestration. Proof-of-concept orchestration toolkits, based on the proposed orchestration approach, were implemented and evaluated in order to assess the feasibility of the approach, its effectiveness and its potential impact on the teaching experience. Comparative analysis and guided orchestration controlled studies were conducted to compare the effectiveness of ad hoc orchestration with streamlined orchestration and to measure the orchestration load, respectively. In addition, a case study of a course that employed a flipped classroom strategy was conducted to assess the feasibility of the proposed approach. The feasibility was further assessed by integrating a workflow, based on the proposed approach, that facilitates the sharing of reusable orchestration packages. The results from the studies suggest that the streamlined approach is more effective when compared to ad hoc orchestration and has a potential to provide a positive user experience. The results also indicate that the approach imposes acceptable orchestration load during scripting of learning activities. Case studies conducted in authentic educational settings suggest that the approach is feasible, and potentially applicable to useful practical usage scenarios. The long-term implications are that streamlining of technology-driven orchestration could potentially improve the effectiveness of educators when orchestrating learning activities
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