Enhanced frequency management for automatic HF radio communication systems

The work described in this thesis aims to enhance the frequency management of automatic high frequency (HF) radio communication systems. During the research programme two new frequency management tools were developed; a chirpsounder monitoring tool to provide accuracy enhancement information for propagation prediction programs and an algorithm designed to allow optimisation of signal formats, so that in-band interference is avoided and the overall system throughput rate is increased. Two new HF communication system architectures are presented, which use system design and programming methodologies derived from the fields of artificial intelligence and computer networks.The characteristics of the HF band are presented from a communicator's viewpoint, rather than the generalised, technical approach normally associated with such reviews. The methods employed by current HF communication systems to overcome the inherent time and frequency variability of HF channels are presented in the form of reviews of propagation, natural noise and co-channel interference prediction methods, embedded real-time channel evaluation algorithms and HF communications system architectures. The inadequacies of these current techniques are analysed. The eradication of their shortcomings is the main objective of the work described in the thesis.The short-term inaccuracies associated with current propagation analysis procedures can limit the performance of automatic HF communication systems. An accuracy enhancement methodology is proposed which makes use of measurements made on oblique chirpsounder transmitters. In order to provide accuracy enhancement data, a chirpsounder-based, propagation monitor was constructed. Its implementation and trials are described and methods of using its output to enhance prediction model accuracy are discussed. Ways in which its performance may be improved are detailed.The theory of a technique, termed "template correlation", which provides automatic HF communication systems with signal format adaptation data in order to enable them to avoid in-band interference, is presented. The objective of this work is to enhance the error-free capacity of a channel via adaptation of the signal. The results of computer simulations and laboratory bench trials of template correlation are presented. Enhancements of the technique in the light of the trials results are included.Two proposed design methodologies for automatic HF communication systems are described. The first uses many of the frequency management tools associated with current automatic systems and it combines the information from these using a blackboard-based expert system architecture. The second proposed design is more conceptual than the first. An inductive expert system is employed to produce rules describing the ways in which an automatic HF system should respond to certain path conditions. Examples of how such a system might function are given.The single, most important factor which has enabled the techniques described in this thesis to be feasible is the availability of cheap but powerful microprocessors. Thus the overall philosophy of the work is to improve the performance of automatic HF communication systems via the incorporation of processing power and "intelligent software" into the communication system's terminals

A Study of Metal Speciation Using a Two-Stage Electrothermal Atomizer. Laser Infrared Fluorescence as a Gc Detector.

A. A two-stage atomic absorption atomizer has been designed and built. It consisted of a molybdenum tube atomizer maintained at high temperatures (2200(DEGREES)C for example) and a molybdenum tube vaporizer which was gradually heated from room temperature up to high temperatures. A sample was placed within the latter section when it was cool, and while the former was heated. Subsequently, the vaporization section was gradually heated and the evolved gases were entrained by the carrier gas through the atomization section and into the optical lightpath. Atomic absorption versus temperature curves were obtained for Pb, Zn and Cd compounds. The resultant data were similar in many respects to those obtained by conventional thermal analysis but at much lower concentrations (or about 10(\u27-8) g). Low temperature peaks were observed using the two-stage atomizer indicating atomization of salts volatilized at low temperatures. A similar study with a PE(.)403 graphite furnace revealed no low temperature peaks, presumably because atomization of low temperatures was not achieved. Solutions of lead halides gave peaks corresponding to the vaporized lead halide as well as to the oxide. Similar results were also observed with cadmium solutions. These gave an indication of the form of the metal compounds that was being volatilized from each solution. Lead in air particulates appeared to be present as the oxide and other unidentified forms. This preliminary study indicated that the technique shows high potential for speciation of metal salts at low concentrations. B. Following encouraging work on remote sensing of atmospheric pollutants using laser induced IR fluorescence, the phenomenon was studied as an in situ GC detector. Results showed that collision deactivation on the walls of the detector greatly reduced fluorescence intensity. This essentially vitiated the uses of this technique as a sensitive, continuous flow GC detector

Reconsultation, self-reported health status and costs following treatment at a musculoskeletal Clinical Assessment and Treatment Service (CATS): a 12-month prospective cohort study

Objectives To determine (1) reconsultation frequency, (2) change in self-reported health status, (3) baseline factors associated with reconsultation and change in health status and (4) associated healthcare costs and quality-adjusted life-years (QALYs), following assessment at a musculoskeletal Clinical and Assessment Treatment Service (CATS). Design Prospective cohort study. Setting Single musculoskeletal CATS at the primary–secondary care interface. Participants 2166 CATS attenders followed-up by postal questionnaires at 6 and 12 months and review of medical records. Outcome measures Primary outcome was consultation in primary care with the same musculoskeletal problem within 12 months. Secondary outcome measures were consultation at the CATS with the same musculoskeletal problem within 12 months, physical function and pain (Short Form-36), anxiety and depression (Hospital Anxiety and Depression Scale), time off work, healthcare costs and QALYs. Results Over 12 months, 507 (38%) reconsulted for the same problem in primary care and 345 (26%) at the CATS. Primary care reconsultation in the first 3 months was associated with baseline pain interference (relative risk ratio 5.33; 95% CI 3.23 to 8.80) and spinal pain (1.75; 1.09 to 2.82), and after 3–6 months with baseline assessment by a hospital specialist (2.06; 1.13 to 3.75). Small mean improvements were seen in physical function (1.88; 95% CI 1.44 to 2.32) and body pain (3.86; 3.38 to 4.34) at 6 months. Poor physical function at 6 months was associated with obesity, chronic pain and poor baseline physical function. Mean (SD) 6-month cost and QALYs per patient were £422.40 (660.11) and 0.257 (0.144), respectively. Conclusions While most patients are appropriate for a ‘one-stop shop’ model, those with troublesome, disabling pain and spinal pain commonly reconsult and have ongoing problems. Services should be configured to identify and address such clinical complexity

The application of predictive modelling for determining bio-environmental factors affecting the distribution of blackflies (Diptera: Simuliidae) in the Gilgel Gibe watershed in Southwest Ethiopia

Blackflies are important macroinvertebrate groups from a public health as well as ecological point of view. Determining the biological and environmental factors favouring or inhibiting the existence of blackflies could facilitate biomonitoring of rivers as well as control of disease vectors. The combined use of different predictive modelling techniques is known to improve identification of presence/absence and abundance of taxa in a given habitat. This approach enables better identification of the suitable habitat conditions or environmental constraints of a given taxon. Simuliidae larvae are important biological indicators as they are abundant in tropical aquatic ecosystems. Some of the blackfly groups are also important disease vectors in poor tropical countries. Our investigations aim to establish a combination of models able to identify the environmental factors and macroinvertebrate organisms that are favourable or inhibiting blackfly larvae existence in aquatic ecosystems. The models developed using macroinvertebrate predictors showed better performance than those based on environmental predictors. The identified environmental and macroinvertebrate parameters can be used to determine the distribution of blackflies, which in turn can help control river blindness in endemic tropical places. Through a combination of modelling techniques, a reliable method has been developed that explains environmental and biological relationships with the target organism, and, thus, can serve as a decision support tool for ecological management strategies

Self management of patients with mild COPD in primary care: randomised controlled trial

Objective: To evaluate the effectiveness of nurse-led telephone health coaching to encourage self-management in a primary care population with mild symptoms of COPD. Design: Pragmatic, multi-centre randomised controlled trial. Setting: 71 general practices in four areas of England. Participants: 577 people, with MRC dyspnoea grade 1 or 2, recruited from primary care COPD registers with spirometry confirmed diagnosis, were randomised to the intervention (n=289) or usual care (n=288). Interventions: Nurse-delivered telephone health coaching intervention, underpinned by Social Cognitive Theory, promoting: accessing smoking cessation services, increasing physical activity, medication management and action planning (4 sessions over 11 weeks; postal information at weeks 16 and 24). Nurses received two days of training. The usual care group received a leaflet about COPD. Main outcome measures: The primary outcome was health related quality of life at 12 months using the short version of the St Georges Respiratory Questionnaire (SGRQ-C). Results: The intervention was delivered with good fidelity: 86% of scheduled calls were delivered; 75% of participants received all four calls. 92% participants were followed-up at six months and 89% at 12 months. There was no difference in SGRQ-C total score at 12 months (mean difference -1.3, 95%CI -3.6 to 0.9; p=0.2). Compared to usual care participants, at six months follow-up, the intervention group reported significantly greater physical activity, more had received a care plan (44% v 30%), rescue packs of antibiotics (37% v 29%) and inhaler technique check (68% v 55%). There were no differences in other secondary outcomes (dyspnoea, smoking cessation, anxiety, depression, self-efficacy, objectively measured physical activity). Conclusions A novel telephone health coaching intervention to promote behaviour change in primary care patients with mild symptoms of dyspnoea did lead to changes in self-management activities, but did not improve health related quality of life. Trial registration Current controlled trials ISRCTN 0671039

Study protocol for a Randomised controlled trial of EArly transjugular intrahepatiC porTosystemic stent–shunt in Acute Variceal Bleeding (REACT-AVB trial)

Introduction: In liver cirrhosis, acute variceal bleeding (AVB) is associated with a 1-year mortality rate of up to 40%. Data on early or pre-emptive transjugular intrahepatic portosystemic stent–shunt (TIPSS) in AVB is inconclusive and may not reflect current management strategies. Randomised controlled trial of EArly transjugular intrahepatiC porTosystemic stent–shunt in AVB (REACT-AVB) aims to investigate the clinical and cost-effectiveness of early TIPSS in patients with cirrhosis and AVB after initial bleeding control.Methods and analysis: REACT-AVB is a multicentre, randomised controlled, open-label, superiority, two-arm, parallel-group trial with an internal pilot. The two interventions allocated randomly 1:1 are early TIPSS within 4 days of diagnostic endoscopy or secondary prophylaxis with endoscopic therapy in combination with non-selective beta blockers. Patients aged ≥18 years with cirrhosis and Child-Pugh Score 7–13 presenting with AVB with endoscopic haemostasis are eligible for inclusion. The primary outcome is transplant-free survival at 1 year post randomisation. Secondary endpoints include transplant-free survival at 6 weeks, rebleeding, serious adverse events, other complications of cirrhosis, Child-Pugh and Model For End-Stage Liver Disease (MELD) scores at 6 and 12 months, health-related quality of life, use of healthcare resources, cost-effectiveness and use of cross-over therapies. The sample size is 294 patients over a 4-year recruitment period, across 30 hospitals in the UK.Ethics and dissemination: Research ethics committee of National Health Service has approved REACT-AVB (reference number: 23/WM/0085). The results will be submitted for publication in a peer-reviewed journal. A lay summary will also be emailed or posted to participants before publication.Trial registration number: ISRCTN85274829; protocol version 3.0, 1 July 2023

Microparticles: major transport vehicles for distinct microRNAs in circulation

AIMS: Circulating microRNAs (miRNAs) have attracted major interest as biomarkers for cardiovascular diseases. Since RNases are abundant in circulating blood, there needs to be a mechanism protecting miRNAs from degradation. We hypothesized that microparticles (MP) represent protective transport vehicles for miRNAs and that these are specifically packaged by their maternal cells. METHODS AND RESULTS: Conventional plasma preparations, such as the ones used for biomarker detection, are shown to contain substantial numbers of platelet-, leucocyte-, and endothelial cell-derived MP. To analyse the widest spectrum of miRNAs, Next Generation Sequencing was used to assess miRNA profiles of MP and their corresponding stimulated and non-stimulated cells of origin. THP-1 (monocytic origin) and human umbilical vein endothelial cell (HUVEC) MP were used for representing circulating MP at a high purity. miRNA profiles of MP differed significantly from those of stimulated and non-stimulated maternal THP-1 cells and HUVECs, respectively. Quantitative reverse transcription-polymerase chain reaction of miRNAs which have been associated with cardiovascular diseases also demonstrated significant differences in miRNA profiles between platelets and their MP. Notably, the main fraction of miRNA in plasma was localized in MP. Furthermore, miRNA profiles of MP differed significantly between patients with stable and unstable coronary artery disease. CONCLUSION: Circulating MP represent transport vehicles for large numbers of specific miRNAs, which have been associated with cardiovascular diseases. miRNA profiles of MP are significantly different from their maternal cells, indicating an active mechanism of selective 'packaging' from cells into MP. These findings describe an interesting mechanism for transferring gene-regulatory function from MP-releasing cells to target cells via MP circulating in blood

Jowett’s Thucydides: A corpus-based analysis of translation as political intervention

Thucydides’ History of the Peloponnesian War is a key text in the classical Greek canon and an important source of insights into the structures and tensions at the heart of ancient Athenian democracy. Consequently, modern interpretations of his analysis have repeatedly played a major role in shaping debates on the viability and desirability of democratic rule. This paper aims to build on previous discussion of Benjamin Jowett's 1881 translation of Thucydides by applying a comparative corpus-based methodology to explore how this translator's own personal politics shaped his re-presentation of this text. The analysis reveals a striking emphasis on the position and activity of democratic leaders throughout Jowett’s version, strongly consistent with the ideology of leadership that he developed during his career as Master of Balliol College, Oxford