Nanodiamond arrays on glass for quantification and fluorescence characterisation

Quantifying the variation in emission properties of fluorescent nanodiamonds is important for developing their wide-ranging applicability. Directed self-assembly techniques show promise for positioning nanodiamonds precisely enabling such quantification. Here we show an approach for depositing nanodiamonds in pre-determined arrays which are used to gather statistical information about fluorescent lifetimes. The arrays were created via a layer of photoresist patterned with grids of apertures using electron beam lithography and then drop-cast with nanodiamonds. Electron microscopy revealed a 90% average deposition yield across 3,376 populated array sites, with an average of 20 nanodiamonds per site. Confocal microscopy, optimised for nitrogen vacancy fluorescence collection, revealed a broad distribution of fluorescent lifetimes in agreement with literature. This method for statistically quantifying fluorescent nanoparticles provides a step towards fabrication of hybrid photonic devices for applications from quantum cryptography to sensing

Development and evaluation of methods to control rabies in Goa state, India

Rabies represents a tragic modern-day paradox; effective methods for its elimination have been available for a century, and yet thousands of children living in low resource settings die of the disease in abject suffering every year. Countries across Latin America eliminated the dog rabies virus through coordinated mass vaccination campaigns targeting the reservoir dog population, but large-scale control efforts have failed to progress in much of Africa and Asia. An estimated 20,000 people die of rabies each year in India, representing one third of the global total. Recent innovations in human medicine have improved access to life-saving post-exposure prophylaxis, however the close relationship between people and an ever-increasing dog population make a One Health approach axiomatic to rabies elimination. Without effective strategies to monitor and control the disease in dogs, the issue of dog transmitted rabies will continue ad infinitum. The work presented in this thesis explores operational approaches to rabies control in Goa State, India from 2013 to 2022 through a collaboration between Mission Rabies and the Government of Goa. A novel smartphone app developed during nascent campaigns formed the foundation of programme management and evaluation. The technology leveraged the enhanced data-capture and transmission capabilities of smartphones to improve the efficiency, efficacy, and political potency of mass dog vaccination campaigns in Goa and at project sites globally. Two-way data transfer between programme managers and the remote vaccination workforce within the platform revolutionised efficient spatial deployment of resource and aggregated the details of over 600,000 individual dog vaccination events in near-real time. Analysis of this high-resolution programmatic data garnered new insights into dog distribution, population composition, and parenteral vaccination accessibility across the urban-rural continuum that informed data-driven optimisation of the vaccination strategy. Concurrent advancement of state-level rabies surveillance systems enabled monitoring of the impact of vaccination and education activities. Human rabies deaths declined to zero and the dog rabies virus was eliminated from large areas of the state, with persistence in regions bordering endemic populations. Goa became the first state in India to become a ‘Rabies Controlled Area’ in 2021 and the programme was found to be ‘very cost-effective’ by WHO criteria for public health interventions. In recognising the operational and logistical constraints of existing mass dog vaccination methods, the potential incorporation of oral rabies vaccination of dogs was explored. A pilot study identified methods that could cost-effectively increase vaccination coverage in difficult to access dog populations, whilst also reducing human resource requirements. The results of a second study supported the use of baits made of an egg-based construct which met requirements of being widely palatable to dogs, culturally acceptable, and potentially mass producible. The findings of this thesis provide insights for advancing feasible and politically attractive solutions for the elimination of rabies at scale through the lens of One Health. Mobile technology, developed through field experience, drove a step-change in the spatial coordination of remote vaccination resource and data quality. Detailed understanding of reservoir population dynamics offers new opportunities for resource prioritisation and efficiency-savings through modelling of rabies transmission and intervention design. The iterative process of operational learning and refinement will need to continue as campaigns progress to new geographies and scales, however the work in Goa demonstrates that dog rabies control in many parts of India is within reach. By advancing approaches to mass dog vaccination, our generation has an opportunity to change the trajectory of a disease which inflicts profound suffering on people and animals already disadvantaged by circumstance

Proprioceptive perception of phase variability

Previous work has established that judgments of relative phase variability of 2 visually presented oscillators covary with mean relative phase. Ninety degrees is judged to be more variable than 0° or 180°, independently of the actual level of phase variability. Judged levels of variability also increase at 180°. This pattern of judgments matches the pattern of movement coordination results. Here, participants judged the phase variability of their own finger movements, which they generated by actively tracking a manipulandum moving at 0°, 90°, or 180°, and with 1 of 4 levels of Phase Variability. Judgments covaried as an inverted U-shaped function of mean relative phase. With an increase in frequency, 180° was judged more variable whereas 0° was not. Higher frequency also reduced discrimination of the levels of Phase Variability. This matching of the proprioceptive and visual results, and of both to movement results, supports the hypothesized role of online perception in the coupling of limb movements. Differences in the 2 cases are discussed as due primarily to the different sensitivities of the systems to the information

An Exploration of Fairness in the Assessment and Process of Student Group Work

This project was driven by a motivation to be as fair as possible in the assessment of students\u27 group work. Achieving fairness in assessment is a recurrent them in group project assessment literature (Nordberg, 2009). All authors of this report teach modules with group projects, and acknowledged that discrepancies often exist between a mark assigned to a group and an individual\u27s contribution. Our aims were to (a) collectively enhance our understanding of the issues that need to be considered when assessing a group work project and (b) collectively build our confidence in approaches chosen to overcome these challenges. The findings of a literature review on group work assessment informed the creation of a methodology to develop a toolkit which can be referred to when planning and setting group work assignments. An intermediary stage of this process was the development of an algorithm which incorporated user perspectives to assign associated values to assignment outputs and how they are assessed. This subjective user input, whether it is generated within a School, a subject matter or from a large sample of educators, can then be applied by associated users. An intended output of these potential processes is that the tailored toolkits can assist educators and/or programmes regardless of their teaching philosophy. Flash-cards were developed as a prototype of how the toolkit information can be visualised

Heterocyst placement strategies to maximize growth of cyanobacterial filaments

Under conditions of limited fixed-nitrogen, some filamentous cyanobacteria develop a regular pattern of heterocyst cells that fix nitrogen for the remaining vegetative cells. We examine three different heterocyst placement strategies by quantitatively modelling filament growth while varying both external fixed-nitrogen and leakage from the filament. We find that there is an optimum heterocyst frequency which maximizes the growth rate of the filament; the optimum frequency decreases as the external fixed-nitrogen concentration increases but increases as the leakage increases. In the presence of leakage, filaments implementing a local heterocyst placement strategy grow significantly faster than filaments implementing random heterocyst placement strategies. With no extracellular fixed-nitrogen, consistent with recent experimental studies of Anabaena sp. PCC 7120, the modelled heterocyst spacing distribution using our local heterocyst placement strategy is qualitatively similar to experimentally observed patterns. As external fixed-nitrogen is increased, the spacing distribution for our local placement strategy retains the same shape while the average spacing between heterocysts continuously increases.Comment: This is an author-created, un-copyedited version of an article accepted for publication in Physical Biology. IOP Publishing Ltd is not responsible for any errors or omissions in this version of the manuscript or any version derived from it. The definitive publisher-authenticated version will be available onlin

Does What Goes up Also Come Down? Using a Recruitment Model to Balance Alewife Nutrient Import and Export

Migrating adult Alewives Alosa pseudoharengus are a source of marine-derived nutrients on the East Coast of North America, importing nitrogen and phosphorus into freshwater habitats. Juvenile migrants subsequently transport freshwater-derived nutrients into the ocean. We developed a deterministic model to explore the theoretical nutrient dynamics of Alewife migrations at differing spawner abundances. Net nutrient balance was calculated relative to these abundances along the spawner–recruit curve. The ecological consequences of these subsidies in a particular watershed depend on the magnitude of adult escapement relative to the habitat\u27s carrying capacity for juveniles. At low escapement levels and assuming complete habitat access, the number of recruits produced per spawner was high and juvenile nutrient export dominated. At high escapement levels, fewer recruits were produced per spawner because recruitment is density dependent. As a result, adult nutrient import dominated. At varying levels of freshwater productivity and fisheries mortality for upstream spawners, this trend remained the same while the magnitude of the endpoints changed. Productivity level was the major determinant of export, while fisheries mortality had the strongest effect on adult import. The dynamics of this nutrient trade-off are important for managers to consider as a recovering population will likely shift from net export to net import as escapement increases. This transition will be sensitive to both harvest rates and to fish passage efficacy at dams and other barriers

Spectroscopy of a Cooper-Pair box in the Autler-Townes configuration

A theoretical spectroscopic analysis of a microwave driven superconducting charge qubit (Cooper-pair box coupled) to an RLC oscillator model is performed. By treating the oscillator as a probe through the backreaction effect of the qubit on the oscillator circuit, we extract frequency splitting features analogous to the Autler-Townes effect from quantum optics, thereby extending the analogies between superconducting and quantum optical phenomenology. These features are found in a frequency band that avoids the need for high frequency measurement systems and therefore may be of use in qubit characterization and coupling schemes. In addition we find this frequency band can be adjusted to suit an experimental frequency regime by changing the oscillator frequency.Comment: 13 pages, 7 figures. v2: Revised version after referee comments. Accepted for publication by Physical Review