Flame hydrolysis deposition of photosensitive silicate layers suitable for the definition of waveguiding structures through direct ultraviolet writing

This thesis presents the construction of equipment suitable for the fabrication of doped silicate layers through use of the Flame Hydrolysis Deposition technique. The subsequent optimisation of equipment and deposition processes has seen the realisation of fully dense amorphous silica layers doped with Phosphorus, Boron and Germanium. Accurate control of dopant inclusion has allowed the independent control of processing properties and optical characteristics, while maintaining the tolerances imposed by waveguiding. The Flame Hydrolysis Deposition Technique has been applied to the fabrication of three layer nominally index matched planar waveguiding structures, consisting of low photosensitivity cladding layers and high photosensitivity core layers. Application of the direct UV writing technique to planar structures has been investigated, and the induced physical and optical effects characterised. The additional application of the Deuterium loading process has been used to further enhance photosensitivity and has resulted in the production of channel waveguides with propagation losses of ~0.2dB/cm and relative core refractive indices of the order 1x10

Screening for familial hypercholesterolaemia in primary care: Time for general practice to play its part

Fifty per cent of first-degree relatives of index cases with familial hypercholesterolemia (FH) inherit the disorder. Despite cascade screening being the most cost-effective method for detecting new cases, only a minority of individuals with FH are currently identified. Primary care is a key target area to increase identification of new index cases and initiate cascade screening, thereby finding close relatives of all probands. Increasing public and health professional awareness about FH is essential. In the United Kingdom and in Australia, most of the population are reviewed by a General Practitioner (GP) at least once over a three-year period, offering opportunities to check for FH as part of routine clinical consultations. Such opportunistic approaches can be supplemented by systematically searching electronic health records with information technology tools that identify high risk patients. GPs can help investigate and implement results of this data retrieval. Current evidence suggests that early detection of FH and cascade testing meet most of the criteria for a worthwhile screening program. Among heterozygous patients the long latent period before the expected onset of coronary artery disease provides an opportunity for initiating effective drug and lifestyle changes. The greatest challenge for primary care is to implement an efficacious model of care that incorporates sustainable identification and management pathways

(Anti)viral Material Design Guided by Scattering Methods

Viruses are nature’s own nanoparticles that are highly symmetric and monodisperse in size and shape with well-defined surface chemistry. They have evolved for optimal cell interactions, genetic information delivery and replication by the host cell over millions of years. These features render them into very efficient pathogens that place a severe burden onto the health of our society. At the same time, they are highly interesting objects for colloidal studies and building blocks for advanced bio-inspired materials for health applications. Their characterisation requires sophisticated experimental techniques such as scattering of X-rays, neutrons, and light to probe structures and interactions from the nanometre to the micrometre length-scale in solution. This contribution summarizes the recent progress in the field of virus self-assembly and virus-based biopolymer composites for advanced material design. It discusses the advances and highlights some of the challenges in the characterization of structure and dynamics in these materials with a focus on scattering techniques. It further demonstrates selected applications in the field of food and water purification

Unsupervised learning for text-to-speech synthesis

This thesis introduces a general method for incorporating the distributional analysis of textual and linguistic objects into text-to-speech (TTS) conversion systems. Conventional TTS conversion uses intermediate layers of representation to bridge the gap between text and speech. Collecting the annotated data needed to produce these intermediate layers is a far from trivial task, possibly prohibitively so for languages in which no such resources are in existence. Distributional analysis, in contrast, proceeds in an unsupervised manner, and so enables the creation of systems using textual data that are not annotated. The method therefore aids the building of systems for languages in which conventional linguistic resources are scarce, but is not restricted to these languages. The distributional analysis proposed here places the textual objects analysed in a continuous-valued space, rather than specifying a hard categorisation of those objects. This space is then partitioned during the training of acoustic models for synthesis, so that the models generalise over objects' surface forms in a way that is acoustically relevant. The method is applied to three levels of textual analysis: to the characterisation of sub-syllabic units, word units and utterances. Entire systems for three languages (English, Finnish and Romanian) are built with no reliance on manually labelled data or language-specific expertise. Results of a subjective evaluation are presented

Evaluation of resistive-plate-chamber-based TOF-PET applied to in-beam particle therapy monitoring

Particle therapy is a highly conformal radiotherapy technique which reduces the dose deposited to the surrounding normal tissues. In order to fully exploit its advantages, treatment monitoring is necessary to minimize uncertainties related to the dose delivery. Up to now, the only clinically feasible technique for the monitoring of therapeutic irradiation with particle beams is Positron Emission Tomography (PET). In this work we have compared a Resistive Plate Chamber (RPC)-based PET scanner with a scintillation-crystal-based PET scanner for this application. In general, the main advantages of the RPC-PET system are its excellent timing resolution, low cost, and the possibility of building large area systems. We simulated a partial-ring scannerbeam monitoring, which has an intrinsically low positron yield compared to diagnostic PET. In addition, for in-beam PET there is a further data loss due to the partial ring configuration. In order to improve the performance of the RPC-based scanner, an improved version of the RPC detector (modifying the thickness of the gas and glass layers), providing a larger sensitivity, has been simulated and compared with an axially extended version of the crystal-based device. The improved version of the RPC shows better performance than the prototype, but the extended version of the crystal-based PET outperforms all other options. based on an RPC prototype under construction within the Fondazione per Adroterapia Oncologica (TERA). For comparison with the crystal-based PET scanner we have chosen the geometry of a commercially available PET scanner, the Philips Gemini TF. The coincidence time resolution used in the simulations takes into account the current achievable values as well as expected improvements of both technologies. Several scenarios (including patient data) have been simulated to evaluate the performance of different scanners. Initial results have shown that the low sensitivity of the RPC hampers its application to hadro

COVID-19 in Africa : rethinking the tools to manage future pandemics

Corona virus disease 2019 (COVID-19) remains an incurable, progressive pneumonia-like illness characterized by fever, dry cough, fatigue, and headache during its early stages. COVID-19 has ultimately resulted in mortality in at least 2 million people worldwide. Millions of people globally have already been affected by this disease, and the numbers are expected to increase, perhaps until an effective cure or vaccine is identified. Although Africa was initially purported by the World Health Organization (WHO) to be severely hit by the pandemic, Africa recorded the least number of cases during the first wave, with lowest rates of infections, compared to Asia, Europe, and the Americas. This statistic might be attributed to the low testing capacity, existing public health awareness and lessons learnt during Ebola epidemic. Nonetheless, the relatively low rate of infection should be an opportunity for Africa to be better prepared to overcome this and future epidemics. In this paper, the authors provide insights into the dynamics and transmission of the severe acute respiratory syndrome corona virus (SARS-CoV-2) during the first wave of the pandemic; possible explanations into the relatively low rates of infection recorded in Africa; with recommendations for Africa to continue to fight Covid-19; and position itself to effectively manage future pandemics. © 2021 Emahi I et al

The diminishing state of shared reality on US television news

The potential for a large, diverse population to coexist peacefully is thought to depend on the existence of a ``shared reality:'' a public sphere in which participants are exposed to similar facts about similar topics. A generation ago, broadcast television news was widely considered to serve this function; however, since the rise of cable news in the 1990s, critics and scholars have worried that the corresponding fragmentation and segregation of audiences along partisan lines has caused this shared reality to be lost. Here we examine this concern using a unique combination of data sets tracking the production (since 2012) and consumption (since 2016) of television news content on the three largest cable and broadcast networks respectively. With regard to production, we find strong evidence for the ``loss of shared reality hypothesis:'' while broadcast continues to cover similar topics with similar language, cable news networks have become increasingly distinct, both from broadcast news and each other, diverging both in terms of content and language. With regard to consumption, we find more mixed evidence: while broadcast news has indeed declined in popularity, it remains the dominant source of news for roughly 50\% more Americans than does cable; moreover, its decline, while somewhat attributable to cable, appears driven more by a shift away from news consumption altogether than a growth in cable consumption. We conclude that shared reality on US television news is indeed diminishing, but is more robust than previously thought and is declining for somewhat different reasons

pH driven colloidal transformation of MS2 virus particles for water purification

Viral infection due to contaminated drinking water is the main cause of infantile death by diarrheal disease [1]. Viruses are difficult to remove by common gravity driven filters due to their nanometer scale size. With the global goal of improving virus removal in drinking water treatments, the colloidal structure of a virus model, MS2 bacteriophage, has been investigated; the effects of pH and Suwannee River natural organic matter in water have been studied [2]. Dynamic light scattering, small angle X-ray scattering and cryogenic transmission electron microscopy were used to characterize the colloidal structure of MS2 in water. The results show that the bacteriophage MS2 is a spherical particle with a core-shell type structure and a total diameter of 27nm. The RNA core has a radius of about 8nm and the protein shell forming the virus capsid is about 6nm thick. The water pH was discovered to have a major influence on the colloidal structure of the virus: at pH above 5, interparticle repulsions stabilize the virus solution. A decrease in pH to 3 led to diminishing of the repulsion forces and micrometer sized virus aggregates. This aggregation process was reversible upon circulating the water pH. In addition, the presence of Suwannee River natural organic matter that simulates the organic components in surface water was found to sterically stabilize the virus particles, reducing aggregates size and promoting disaggregation with pH increase. These findings will allow a better understanding of virus interactions and can guide the design of advanced water filtration processes for virus removal. Please click Additional Files below to see the full abstract