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Development of rapid screening assays for the detection of foodborne pathogens in food
Get PDFFast and simple detection methods of bacteria and viruses in foodsamples have become a basic requirement in many fields, such as food production. Most rapid methods depend on immunological techniques and bio-sensing rather than the traditional culture based techniques. The purpose of this study was to develop numerous fast, simple and cheap assays to detect pathogenic bacteria and viruses in food samples and food processing plants, the methods are based on different scientific principles, such as immunological techniques with specific binding elements (antibodies and aptamers) or general capturing elements (lactoferrin), in addition to molecular methods, such as loop mediated isothermal amplification (LAMP), in the first approach, a simple and reliable colorimetric immune sensor using specific antibodies was developed and evaluated as a novel and rapid detection platform for foodborne pathogenic bacteria on surfaces of poultry processing plants, cotton swabs were activated by aldehyde groups to be used as a substrate and pre-concentration matrix for pathogens. The assay was tested on artificially contaminated surfaces with different concentrations 10[1]-10[8] CFU/ml of Salmonella typhimurium, Salmonella entritidis, Staphylococcus aureus and Campylobacter jejuni. In the second approach, the rapid detection of S. Typhimurium, S. entritidis, S. aureus,C. jejuni in addition to Norovirus was achieved using a colorimetric immune sensor, this method can be used for the on-site detection of pathogenic bacteria on the surfaces of chicken meat. In this assay, activated cotton swabs coupled with lactoferrin were used for preconcentrating pathogenic bacteria from the contaminated chicken surfaces, the color intensity of the cotton surfaces increased with the increasing concentration of the pathogenic bacteria. The detection limit was found to be as low as 10 CFU/ml for S. entritidis, 100 CFU/ml for S. entirica serovar typhimurium and C. jejuni and 1000 CFU/ml for S. aureus. This method is highly specific and was further confirmed by the LAMPmethod, the same technique was used to detect Norovirus in food samples. In the third approach, a combination of the LAMP technique and nanotechnology was used for the detection of Salmonella, E. coli. 0157H and C. jejuni in poultry processing plants. Lactoferrin was used as a cross linker between the amplified DNA sequences and with less than 50 nm containing carboxylic acid functional groups, stainless-steel surfaces were artificially contaminated with different concentrations of bacterial cultures in the range 10 to 108 CFU. Positive samples were visually detected by observing the aggregation of dyed nanospheres forming a disc near the top of solution. Conversely, negative samples were characterised by dispersed dye in the solution. This assay showed very good sensitivity, ranging between 10 CFU in both Salmonella and E.coli, and 100 CFU in the case of C. jejuni. The last approach was a fluorescence-based study for mapping the highest affinity truncated aptamers from the full-length sequence and its integration in a graphene oxide platform for the detection of S. enteritis to identify the best truncated sequence. Molecular beacons were used as well as a displacement assay design. The detection limit of the aptasensors fabricated using the truncated aptamer was lower than the full-length aptamer. Moreover, the aptasensors did not show significant cross reactivity with other related bacteria such as S. typhimurium, S. aureusand E. coli. The fluorescent/graphene oxide aptasensors also demonstrated good recovery for the detection of S. entirica serovar enteritidis from spiked milk samples.Fast and simple detection methods of bacteria and viruses in foodsamples have become a basic requirement in many fields, such as food production. Most rapid methods depend on immunological techniques and bio-sensing rather than the traditional culture based techniques. The purpose of this study was to develop numerous fast, simple and cheap assays to detect pathogenic bacteria and viruses in food samples and food processing plants, the methods are based on different scientific principles, such as immunological techniques with specific binding elements (antibodies and aptamers) or general capturing elements (lactoferrin), in addition to molecular methods, such as loop mediated isothermal amplification (LAMP), in the first approach, a simple and reliable colorimetric immune sensor using specific antibodies was developed and evaluated as a novel and rapid detection platform for foodborne pathogenic bacteria on surfaces of poultry processing plants, cotton swabs were activated by aldehyde groups to be used as a substrate and pre-concentration matrix for pathogens. The assay was tested on artificially contaminated surfaces with different concentrations 10[1]-10[8] CFU/ml of Salmonella typhimurium, Salmonella entritidis, Staphylococcus aureus and Campylobacter jejuni. In the second approach, the rapid detection of S. Typhimurium, S. entritidis, S. aureus,C. jejuni in addition to Norovirus was achieved using a colorimetric immune sensor, this method can be used for the on-site detection of pathogenic bacteria on the surfaces of chicken meat. In this assay, activated cotton swabs coupled with lactoferrin were used for preconcentrating pathogenic bacteria from the contaminated chicken surfaces, the color intensity of the cotton surfaces increased with the increasing concentration of the pathogenic bacteria. The detection limit was found to be as low as 10 CFU/ml for S. entritidis, 100 CFU/ml for S. entirica serovar typhimurium and C. jejuni and 1000 CFU/ml for S. aureus. This method is highly specific and was further confirmed by the LAMPmethod, the same technique was used to detect Norovirus in food samples. In the third approach, a combination of the LAMP technique and nanotechnology was used for the detection of Salmonella, E. coli. 0157H and C. jejuni in poultry processing plants. Lactoferrin was used as a cross linker between the amplified DNA sequences and with less than 50 nm containing carboxylic acid functional groups, stainless-steel surfaces were artificially contaminated with different concentrations of bacterial cultures in the range 10 to 108 CFU. Positive samples were visually detected by observing the aggregation of dyed nanospheres forming a disc near the top of solution. Conversely, negative samples were characterised by dispersed dye in the solution. This assay showed very good sensitivity, ranging between 10 CFU in both Salmonella and E.coli, and 100 CFU in the case of C. jejuni. The last approach was a fluorescence-based study for mapping the highest affinity truncated aptamers from the full-length sequence and its integration in a graphene oxide platform for the detection of S. enteritis to identify the best truncated sequence. Molecular beacons were used as well as a displacement assay design. The detection limit of the aptasensors fabricated using the truncated aptamer was lower than the full-length aptamer. Moreover, the aptasensors did not show significant cross reactivity with other related bacteria such as S. typhimurium, S. aureusand E. coli. The fluorescent/graphene oxide aptasensors also demonstrated good recovery for the detection of S. entirica serovar enteritidis from spiked milk samples
Fatigue measurement in renal cancer patients and preclinical evaluation of combination therapy in RCC
Get PDFIn the United Kingdom, although only 3% of all new cancer diagnoses among men and even less for women are of kidney cancer, reports have also shown that the incidence of kidney cancer has increased not only in the United Kingdom, but also worldwide. In fact, in the United Kingdom, kidney cancer mortality rates have increased by 71% since the early 1970s. In response, the treatment and management of kidney cancer depends on whether the disease is clinically localised or metastasised at initial diagnosis.;In metastatic patients, molecularly targeted therapies, including those using tyrosine kinase inhibitors (TKI) sunitinib and pazopanib, have largely replaced therapies with immunotherapy agents, which are less efficacious and more toxic than TKI. However, fatigue remains a commonly reported side effect of kidney cancer treatment involving TKI, which might make them intolerable. Accordingly, accurately measuring fatigue and identifying possible reasons for its onset and increase are vital to its early management.;In chapter 2, we measured fatigue in kidney cancer patients received sunitinib or pazopanib by using the Functional Assessment Chronic Illness Therapy for Fatigue (FACIT-F) tool. We also evaluated cancer symptoms and the impact of sunitinib and pazopanib on the quality of life of patients according to core items on the M. D. Anderson Symptom Inventory in four consecutive cycles. Among the 65 recruited patients receiving treatment at Beatson West of Scotland Cancer Centre in Glasgow, who participated in the study, 47 completed all four treatment cycles.;Our results showed that the mean fatigue score range, based on the FACIT-F tool, in participants was 29.5-31.8, which considered diagnostic fatigue of < 34 based on the cutoff point of FACIT-F. Furthermore, we found that the severity of fatigue score increased when cancer symptoms increased in those patients.;Such results encouraged us to investigate a combination therapy proposed in the literature to minimise the incidence of side effects with a combination of reduced dose of TKI, sunitinib or pazopanib, and radiotherapy. In chapter 3, we report a preclinical laboratory study that we conducted to examine the efficacy of sunitinib and pazopanib in killing renal cancer cells in vitro when used as single agents, as well as their potential use in combination studies.;Our results demonstrated that combination therapy was superior to monotherapy and that both sunitinib and pazopanib as single agents and in combination therapy with radiotherapy could induce apoptosis in both renal cell lines, 786-O and ACHN. Furthermore, we report our investigation into the cytotoxic effects of disulfiram, an anti-alcoholism drug not previously interrogated, in renal cell cancer alone and in combination with radiotherapy. Disulfiram demonstrated a cytotoxic effect, but not in a dose-dependent manner.;Our results additionally demonstrated that copper could enhance the cytotoxicity of disulfiram in renal cell lines only with a low dose of disulfiram ≤ 10 μM. By contrast, radiotherapy combined with disulfiram ± copper did not decrease cell viability, and disulfiram alone could induce apoptosis in renal cell lines.;In sum, our results reveal that fatigue is a significant issue for most kidney cancer patients receiving sunitinib or pazopanib. TKI agents could improve the radiosensitivity of the renal cancer cell line and constitute an interesting option for managing kidney cancer in the hopes of discovering a novel combination regimen with the same efficacy and with less toxicity. In short, disulfiram exhibits potential anticancer properties in renal cancer cell lines.In the United Kingdom, although only 3% of all new cancer diagnoses among men and even less for women are of kidney cancer, reports have also shown that the incidence of kidney cancer has increased not only in the United Kingdom, but also worldwide. In fact, in the United Kingdom, kidney cancer mortality rates have increased by 71% since the early 1970s. In response, the treatment and management of kidney cancer depends on whether the disease is clinically localised or metastasised at initial diagnosis.;In metastatic patients, molecularly targeted therapies, including those using tyrosine kinase inhibitors (TKI) sunitinib and pazopanib, have largely replaced therapies with immunotherapy agents, which are less efficacious and more toxic than TKI. However, fatigue remains a commonly reported side effect of kidney cancer treatment involving TKI, which might make them intolerable. Accordingly, accurately measuring fatigue and identifying possible reasons for its onset and increase are vital to its early management.;In chapter 2, we measured fatigue in kidney cancer patients received sunitinib or pazopanib by using the Functional Assessment Chronic Illness Therapy for Fatigue (FACIT-F) tool. We also evaluated cancer symptoms and the impact of sunitinib and pazopanib on the quality of life of patients according to core items on the M. D. Anderson Symptom Inventory in four consecutive cycles. Among the 65 recruited patients receiving treatment at Beatson West of Scotland Cancer Centre in Glasgow, who participated in the study, 47 completed all four treatment cycles.;Our results showed that the mean fatigue score range, based on the FACIT-F tool, in participants was 29.5-31.8, which considered diagnostic fatigue of < 34 based on the cutoff point of FACIT-F. Furthermore, we found that the severity of fatigue score increased when cancer symptoms increased in those patients.;Such results encouraged us to investigate a combination therapy proposed in the literature to minimise the incidence of side effects with a combination of reduced dose of TKI, sunitinib or pazopanib, and radiotherapy. In chapter 3, we report a preclinical laboratory study that we conducted to examine the efficacy of sunitinib and pazopanib in killing renal cancer cells in vitro when used as single agents, as well as their potential use in combination studies.;Our results demonstrated that combination therapy was superior to monotherapy and that both sunitinib and pazopanib as single agents and in combination therapy with radiotherapy could induce apoptosis in both renal cell lines, 786-O and ACHN. Furthermore, we report our investigation into the cytotoxic effects of disulfiram, an anti-alcoholism drug not previously interrogated, in renal cell cancer alone and in combination with radiotherapy. Disulfiram demonstrated a cytotoxic effect, but not in a dose-dependent manner.;Our results additionally demonstrated that copper could enhance the cytotoxicity of disulfiram in renal cell lines only with a low dose of disulfiram ≤ 10 μM. By contrast, radiotherapy combined with disulfiram ± copper did not decrease cell viability, and disulfiram alone could induce apoptosis in renal cell lines.;In sum, our results reveal that fatigue is a significant issue for most kidney cancer patients receiving sunitinib or pazopanib. TKI agents could improve the radiosensitivity of the renal cancer cell line and constitute an interesting option for managing kidney cancer in the hopes of discovering a novel combination regimen with the same efficacy and with less toxicity. In short, disulfiram exhibits potential anticancer properties in renal cancer cell lines
Spatially and angularly resolved diffuse reflectance spectroscopy for in-situ monitoring of suspension polymerisation reactions
No full textDespite the widespread use of optical spectroscopy for monitoring polymerisation processes, significant challenges remain for its successful application on suspension polymerisation reactions. The high heterogeneity and viscosity of such reaction media make sampling a challenging task and deteriorates the accuracy of reference and spectroscopic measurements. In this thesis, this problem is tackled by taking advantage of the stronger scattering susceptibility of the visible spectral range and the deeper penetration depth offered by the near infrared region. An investigation is carried out to evaluate whether the predictive capability of multivariate calibration models could be improved by introducing new variations in measurement configuration, in particular, spatially and angularly resolved illumination. An empirical approach based on multivariate calibration methods and chemometrics is also proposed for the extraction, pre-processing, fusing and modelling of such multidimensional information. How well these different measurements are integrated and how accurate the multivariate models can be, are one of the main questions of this thesis. They are first studied through a two-component system composed of polystyrene and water, followed by full suspension polymerisation reactions.The results suggest that the accuracy of multivariate calibration models can be improved by (i) including angularly orientated fibres, (ii) fusing information from two or more source-detector separations, (iii) by how data is fused or manipulated,and (iv) by the quality of the measurements. To the best of my knowledge, this work is the first attempt to employ spatially and angularly resolved diffuse reflectance spectroscopy as a Process Analytical Technology (PAT) tool for monitoring suspension polymerisation reactions, and also the first in which a data fusion approach based on Multiblock Partial Least Squares regression (MB-PLS) is evaluated for this purpose.Despite the widespread use of optical spectroscopy for monitoring polymerisation processes, significant challenges remain for its successful application on suspension polymerisation reactions. The high heterogeneity and viscosity of such reaction media make sampling a challenging task and deteriorates the accuracy of reference and spectroscopic measurements. In this thesis, this problem is tackled by taking advantage of the stronger scattering susceptibility of the visible spectral range and the deeper penetration depth offered by the near infrared region. An investigation is carried out to evaluate whether the predictive capability of multivariate calibration models could be improved by introducing new variations in measurement configuration, in particular, spatially and angularly resolved illumination. An empirical approach based on multivariate calibration methods and chemometrics is also proposed for the extraction, pre-processing, fusing and modelling of such multidimensional information. How well these different measurements are integrated and how accurate the multivariate models can be, are one of the main questions of this thesis. They are first studied through a two-component system composed of polystyrene and water, followed by full suspension polymerisation reactions.The results suggest that the accuracy of multivariate calibration models can be improved by (i) including angularly orientated fibres, (ii) fusing information from two or more source-detector separations, (iii) by how data is fused or manipulated,and (iv) by the quality of the measurements. To the best of my knowledge, this work is the first attempt to employ spatially and angularly resolved diffuse reflectance spectroscopy as a Process Analytical Technology (PAT) tool for monitoring suspension polymerisation reactions, and also the first in which a data fusion approach based on Multiblock Partial Least Squares regression (MB-PLS) is evaluated for this purpose
Optimal wireless technologies for the Internet of Things (IoT)
Get PDFThe Internet of Things (IoT) - connection of small smart sensors, actuators and other devices to the Internet - is a key concept within the smart home. To ease deployment, such devices are often wireless and battery powered. An important question is the wireless interface used. As these small sensors are increasing in number, the need to implement these with much more capable and ubiquitous transmission technology is necessary.;The ubiquity of Wi-Fi in homes today makes this an attractive option, but the relatively high power requirements of Wi-Fi conflict with the requirement for long battery life and low maintenance. Lower power alternatives, such as Bluetooth and Zigbee, have been proposed, but these have a much smaller installed base. In addition, many Smart Home products are currently available using 433MHz technology.;This thesis considers whether it is possible to reduce Wi-Fi power usage to the point where cheap Wi-Fi based products can be used instead of other protocols. A low cost Wi-Fi inbuilt IoT prototype was developed and tested for the purpose of the experiment carried out for this thesis, part of Treegreen project. The work in this thesis undertakes power analysis of a wireless sensor with a System on Chip (SoC) Wi-Fi module, with and without a separate microcontroller, optimized for low power usage which can be used to control the Wi-Fi module.;The Wi-Fi chip used within the prototype is the ESP8266- ESP03. Based on the results, in order to optimize the power consumption of the Wi-Fi chip, an MSP430 microcontroller was added onto the existing device. Finally, the IoT data in LTE network is investigated and compared with the real world IoT data.The Internet of Things (IoT) - connection of small smart sensors, actuators and other devices to the Internet - is a key concept within the smart home. To ease deployment, such devices are often wireless and battery powered. An important question is the wireless interface used. As these small sensors are increasing in number, the need to implement these with much more capable and ubiquitous transmission technology is necessary.;The ubiquity of Wi-Fi in homes today makes this an attractive option, but the relatively high power requirements of Wi-Fi conflict with the requirement for long battery life and low maintenance. Lower power alternatives, such as Bluetooth and Zigbee, have been proposed, but these have a much smaller installed base. In addition, many Smart Home products are currently available using 433MHz technology.;This thesis considers whether it is possible to reduce Wi-Fi power usage to the point where cheap Wi-Fi based products can be used instead of other protocols. A low cost Wi-Fi inbuilt IoT prototype was developed and tested for the purpose of the experiment carried out for this thesis, part of Treegreen project. The work in this thesis undertakes power analysis of a wireless sensor with a System on Chip (SoC) Wi-Fi module, with and without a separate microcontroller, optimized for low power usage which can be used to control the Wi-Fi module.;The Wi-Fi chip used within the prototype is the ESP8266- ESP03. Based on the results, in order to optimize the power consumption of the Wi-Fi chip, an MSP430 microcontroller was added onto the existing device. Finally, the IoT data in LTE network is investigated and compared with the real world IoT data
Condition monitoring of wind turbines using micro-doppler information
Get PDFWith the development of modern science technology and awareness of environmental protection, new wnergy technologies have emerged and developed rapidly. Wind power, as a renewable energy source, has played a pivotal role in society which has been deeply researched and promoted around the world in recent years. As wind turbin capacity is gowing, wind turbine blade maintenance test and diagnosis have gradually drawn people's attention, also have become hot points in new energy technologies. Therefore, exploring the development of wind turbine blade detaction and diagnosis is necessary.;This thesis will adopt radar technology to monitor and diagnose the operation of the wind turbine blade, with a simple and effective way to solve the working condition of wind turbine blades. This study focuses on the design of a running model of wind turbine, within-depth analysis of micro-doppler of radar back scattering signals from wind turbine blades to determine the health of the wind turbine blades, providing the basic data for the maintenance of the wind turbine blades.;Monitor and diagnosis of the whole process is devided into four parts - Theory Analysis, Mathematical Modeling, Algorithm Development and Experimental Design. The thesis will focus on the wind turbine blade daily operation problems -- vibration, corrosion, and other problems, through the data model analysis, to give a more efficient and accurate detection and diagnosis, to provide a remote and online protection for the safe operation of wind turbine blades.With the development of modern science technology and awareness of environmental protection, new wnergy technologies have emerged and developed rapidly. Wind power, as a renewable energy source, has played a pivotal role in society which has been deeply researched and promoted around the world in recent years. As wind turbin capacity is gowing, wind turbine blade maintenance test and diagnosis have gradually drawn people's attention, also have become hot points in new energy technologies. Therefore, exploring the development of wind turbine blade detaction and diagnosis is necessary.;This thesis will adopt radar technology to monitor and diagnose the operation of the wind turbine blade, with a simple and effective way to solve the working condition of wind turbine blades. This study focuses on the design of a running model of wind turbine, within-depth analysis of micro-doppler of radar back scattering signals from wind turbine blades to determine the health of the wind turbine blades, providing the basic data for the maintenance of the wind turbine blades.;Monitor and diagnosis of the whole process is devided into four parts - Theory Analysis, Mathematical Modeling, Algorithm Development and Experimental Design. The thesis will focus on the wind turbine blade daily operation problems -- vibration, corrosion, and other problems, through the data model analysis, to give a more efficient and accurate detection and diagnosis, to provide a remote and online protection for the safe operation of wind turbine blades
Open innovation in new drug research : the case of the Indian pharmaceutical sector
Get PDFThe legislative environment in India underwent changes in 2005 leading to product patentprotection for pharmaceuticals. Equipped with superior process capabilities acquired forgeneric manufacturing, the pharmaceutical sector embarked on a journey to undertake radicalinnovation. The aim of the research is to explore how changes in the national environmentand asset profile of firms have influenced openness for research of novel drugs. The reviewof literature, synthesis of conceptual framework and data analysis is shaped by the theoreticalapproaches of national innovation systems (NIS), dynamic capabilities and open innovation.The theoretical lens of national innovation systems enables our understanding of what shapesinnovation behaviour of a firm, open innovation approach provides a description of howfirms adopt open innovation and dynamic capabilities concept supports the interpretation ofwhy firms differ in opening up their boundaries. The answers are examined through ninecases of established and start-up pharmaceutical firms in India.New drug research is challenging and requires collaborative effort predominantly at the drugdiscovery stage. However, in the Indian setting, research networks are minimal and there islittle cohesion within the ecosystem among firms, research institutes and universities. Firmsare opening up their R&D innovation process to foreign partners through open innovationstrategies; in-licensing, out-licensing and collaborative innovation that vary by stage of drugresearch. The open innovation pathways adopted by firms are influenced by four 4Rs -resource supplementation and risk mitigation that initiate open innovation, retention ofcontrol and revenue maximization that impel closed innovation. The insights into the strategictrends of these firms unveil an open innovation framework that is relevant to the openinnovation theory and praxis.The legislative environment in India underwent changes in 2005 leading to product patentprotection for pharmaceuticals. Equipped with superior process capabilities acquired forgeneric manufacturing, the pharmaceutical sector embarked on a journey to undertake radicalinnovation. The aim of the research is to explore how changes in the national environmentand asset profile of firms have influenced openness for research of novel drugs. The reviewof literature, synthesis of conceptual framework and data analysis is shaped by the theoreticalapproaches of national innovation systems (NIS), dynamic capabilities and open innovation.The theoretical lens of national innovation systems enables our understanding of what shapesinnovation behaviour of a firm, open innovation approach provides a description of howfirms adopt open innovation and dynamic capabilities concept supports the interpretation ofwhy firms differ in opening up their boundaries. The answers are examined through ninecases of established and start-up pharmaceutical firms in India.New drug research is challenging and requires collaborative effort predominantly at the drugdiscovery stage. However, in the Indian setting, research networks are minimal and there islittle cohesion within the ecosystem among firms, research institutes and universities. Firmsare opening up their R&D innovation process to foreign partners through open innovationstrategies; in-licensing, out-licensing and collaborative innovation that vary by stage of drugresearch. The open innovation pathways adopted by firms are influenced by four 4Rs -resource supplementation and risk mitigation that initiate open innovation, retention ofcontrol and revenue maximization that impel closed innovation. The insights into the strategictrends of these firms unveil an open innovation framework that is relevant to the openinnovation theory and praxis
Measuring risk perception and risk-taking behaviour when driven by automatic cognitive processing : the development of new methods
Get PDFRisk perception and risk-taking behaviour, are often driven by automatic (implicit) thinking, either in isolation or in combination with reasoned, deliberative thinking. This presents research challenges as measuring automatic thinking requires the use of specialized methods. The main original contributions of this thesis are the development of novel methods that aim to measure risk perception and risk-taking behaviour when driven by automatic thought processing.Drawing on the MODE model and dual process theories of thinking, the thesis presents the development and demonstration of a risk version of the Evaluative Priming Task. This provides an implicit risk attitude measure that can be used as a novel research tool.In order to measure risk-taking behaviour a modification of a current risk behaviour method (the Balloon Analogue Risk Task) was developed. This version includes a priming component, thus allowing for measurement of changes in risk-taking behaviour based on automatic thought processing. This is the first method that can fulfil this aim.The final main contribution of this thesis is a demonstration of the 'affect heuristic' at an automatic (implicit) level of processing. This was achieved by using the new methods. Using these methods facilitated such investigation in a more direct manner than has previously been possible.The development of both methods provides novel research tools for investigation in implicit risk perception and behaviour. Currently, there are limited options for such investigation. The utility of the methods is discussed, including how they could be used in various contexts, such as recruitment or work evaluation. Limitations of the research, suggestions for future research, and the next steps for the further refinement of the methods are discussed.Risk perception and risk-taking behaviour, are often driven by automatic (implicit) thinking, either in isolation or in combination with reasoned, deliberative thinking. This presents research challenges as measuring automatic thinking requires the use of specialized methods. The main original contributions of this thesis are the development of novel methods that aim to measure risk perception and risk-taking behaviour when driven by automatic thought processing.Drawing on the MODE model and dual process theories of thinking, the thesis presents the development and demonstration of a risk version of the Evaluative Priming Task. This provides an implicit risk attitude measure that can be used as a novel research tool.In order to measure risk-taking behaviour a modification of a current risk behaviour method (the Balloon Analogue Risk Task) was developed. This version includes a priming component, thus allowing for measurement of changes in risk-taking behaviour based on automatic thought processing. This is the first method that can fulfil this aim.The final main contribution of this thesis is a demonstration of the 'affect heuristic' at an automatic (implicit) level of processing. This was achieved by using the new methods. Using these methods facilitated such investigation in a more direct manner than has previously been possible.The development of both methods provides novel research tools for investigation in implicit risk perception and behaviour. Currently, there are limited options for such investigation. The utility of the methods is discussed, including how they could be used in various contexts, such as recruitment or work evaluation. Limitations of the research, suggestions for future research, and the next steps for the further refinement of the methods are discussed
Novel diode laser absorption techniques for combustion diagnostics
Get PDFIn-situ optical techniques offer one of the most attractive options for measuring species concentration and spatial distribution profiles in reacting environments, such as flames. The generally non-intrusive nature and spatial resolution of these techniques are now preferred over on extractive sampling, followed by analysis using techniques such as gas chromatography. In this thesis two laser absorption measurement techniques are applied to measure the soot distribution, and acetylene concentration profiles in a flat-flame burner. The in-situ measurement of the distribution of particulate matter in flames is a key step in understanding the mechanism of its formation. Most in-situ measurement systems for this purpose are based on laser induced incandescence where particles are heated using high power laser sources and the increased incandescence emission of the soot particles is detected. However as the soot cools by heat transfer to the surrounding gas, following laser heating, the pressure of the gas is increased creating an acoustic effect. Photoacoustic detection has been applied to quantify low concentrations of particulate matter in ambient air but there have been few applications of photoacoustic detection to the in-situ measurement of particulate matter formation in combustion processes. A novel simple approach using a modulated continuous wave diode laser is presented in this thesis. The measurements taken using this new technique are compared to measurements of the visible emission from the flame, and previous soot distribution measurements using laser induced incandescence. Absorption spectroscopy using near-infrared tunable diode lasers has been applied to measure species in several harsh environments such as aero-engine exhaust plumes, flames, and other industrial processes. Simple single pass absorption techniques are not always suitable for this purpose due to the low absorption of the target species, either due to low concentration or weak absorption line-strength at high temperatures. One method to increase the sensitivity of such techniques is by using cavity enhanced methods which increase the effective path length of the laser through the absorbing medium. One such cavity enhanced method is Cavity Ring-Down Spectroscopy (CRDS). CRDS uses a cavity constructed of highly reflecting mirrors, laser light is then coupled into this cavity and absorption measurements can be evaluated from the decay rate of light from the cavity. The design and, novel application of continuous wave CRDS to measure the concentration profile of acetylene in the flat-flame burner is presented. Difficulties in deriving an absolute acetylene concentration from the measured ringdown times were encountered due to the large number of interfering features. Serveral fitting and extraction techniques are applied and compared to attempt to overcome these difficulties.In-situ optical techniques offer one of the most attractive options for measuring species concentration and spatial distribution profiles in reacting environments, such as flames. The generally non-intrusive nature and spatial resolution of these techniques are now preferred over on extractive sampling, followed by analysis using techniques such as gas chromatography. In this thesis two laser absorption measurement techniques are applied to measure the soot distribution, and acetylene concentration profiles in a flat-flame burner. The in-situ measurement of the distribution of particulate matter in flames is a key step in understanding the mechanism of its formation. Most in-situ measurement systems for this purpose are based on laser induced incandescence where particles are heated using high power laser sources and the increased incandescence emission of the soot particles is detected. However as the soot cools by heat transfer to the surrounding gas, following laser heating, the pressure of the gas is increased creating an acoustic effect. Photoacoustic detection has been applied to quantify low concentrations of particulate matter in ambient air but there have been few applications of photoacoustic detection to the in-situ measurement of particulate matter formation in combustion processes. A novel simple approach using a modulated continuous wave diode laser is presented in this thesis. The measurements taken using this new technique are compared to measurements of the visible emission from the flame, and previous soot distribution measurements using laser induced incandescence. Absorption spectroscopy using near-infrared tunable diode lasers has been applied to measure species in several harsh environments such as aero-engine exhaust plumes, flames, and other industrial processes. Simple single pass absorption techniques are not always suitable for this purpose due to the low absorption of the target species, either due to low concentration or weak absorption line-strength at high temperatures. One method to increase the sensitivity of such techniques is by using cavity enhanced methods which increase the effective path length of the laser through the absorbing medium. One such cavity enhanced method is Cavity Ring-Down Spectroscopy (CRDS). CRDS uses a cavity constructed of highly reflecting mirrors, laser light is then coupled into this cavity and absorption measurements can be evaluated from the decay rate of light from the cavity. The design and, novel application of continuous wave CRDS to measure the concentration profile of acetylene in the flat-flame burner is presented. Difficulties in deriving an absolute acetylene concentration from the measured ringdown times were encountered due to the large number of interfering features. Serveral fitting and extraction techniques are applied and compared to attempt to overcome these difficulties
Empirical analyses on international investments
Get PDFThis thesis draws motivation from the stylized fact that investors do not diversify their investments well enough to reap the benefits of international diversification. Hence, it empirically examines and provides new insights into three different aspects related to suboptimal international investments: determinants of suboptimal foreign allocation, the impact of such suboptimal allocation on the cost of debt, and a possible avenue to enhance the level of foreign investment. The first empirical chapter identifies that though both economic and non-economic factors are important in driving foreign bias in bond investments, it is the non-economic factors that are more important in influencing the bias. This chapter further shows that the importance of non-economic factors gets augmented during periods of debt crisis whereas that of economic factors remain unchanged. The second empirical chapter demonstrates that foreign bond bias has a positive impact on the cost of debt: higher level of foreign bias in a market leads to a lower cost of debt in that market. The third empirical chapter provides evidence that enforcement of existing corporate governance regulations in firms leads to higher foreign ownership in firms. The findings presented in this thesis are robust to various checks and are of interest to policymakers, academics, and firm owners. Being aware of the costs associated with suboptimal foreign investment and being cognizant of the various economic and non-economic factors that can influence foreign allocation can help formulate appropriate policies to enhance foreign investments closer towards the prescribed optimal level. The findings that better corporate governance is associated with higher level of foreign investment is of particular interest to firm owners, especially in emerging markets. This thesis also provides avenues for further research and this can be beneficial to academics.This thesis draws motivation from the stylized fact that investors do not diversify their investments well enough to reap the benefits of international diversification. Hence, it empirically examines and provides new insights into three different aspects related to suboptimal international investments: determinants of suboptimal foreign allocation, the impact of such suboptimal allocation on the cost of debt, and a possible avenue to enhance the level of foreign investment. The first empirical chapter identifies that though both economic and non-economic factors are important in driving foreign bias in bond investments, it is the non-economic factors that are more important in influencing the bias. This chapter further shows that the importance of non-economic factors gets augmented during periods of debt crisis whereas that of economic factors remain unchanged. The second empirical chapter demonstrates that foreign bond bias has a positive impact on the cost of debt: higher level of foreign bias in a market leads to a lower cost of debt in that market. The third empirical chapter provides evidence that enforcement of existing corporate governance regulations in firms leads to higher foreign ownership in firms. The findings presented in this thesis are robust to various checks and are of interest to policymakers, academics, and firm owners. Being aware of the costs associated with suboptimal foreign investment and being cognizant of the various economic and non-economic factors that can influence foreign allocation can help formulate appropriate policies to enhance foreign investments closer towards the prescribed optimal level. The findings that better corporate governance is associated with higher level of foreign investment is of particular interest to firm owners, especially in emerging markets. This thesis also provides avenues for further research and this can be beneficial to academics
Peak-ratio analysis method for enhancement of LOM protection using M class PMUs
Get PDFLoss of Mains (LOM) occurs when part of the utility network containing distributed generation (DG) is disconnected from the remainder of the system. Detecting LOM will become more important in the future as higher amounts of DG will be connected to increase the use of renewable energy sources, to reduce emissions and to reduce power transmission losses. In some cases, DG can be capable of supplying loads within an island and the islanded system can remain stable.;However, safety issues arise if LOM persists and, accordingly, islanded operation is not permitted in the majority of utility systems throughout the world. Wide area monitoring systems, using synchronised phasor measurements, which are beginning to play an increasing role in monitoring and control in transmission networks, may offer opportunities to improve the performance of LOM protection in distribution networks, but may require some form of communications.;A novel technique for LOM detection, using Phasor Measurement Unit (PMU) data, is described in this thesis. The technique, known as the Peak Ratio Analysis Method (PRAM), is shown to improve both the sensitivity and stability of LOM protection when compared to prevailing techniques.;The technique is based on a Rate of Change of Frequency (ROCOF) measurement from M-class PMUs, but the key novelty of the method lies in the fact that it employs a new 'peak-ratio' analysis of the measured ROCOF waveform during any frequency disturbance to determine whether the potentially-islanded element of the network remains connected to the main system or not (i.e. it detects when islanding, or loss of mains, has occurred).;The proposed technique is described and several examples of its operation are compared with three competing LOM protection methods that have all been widely used by industry and/or reported in the literature: standard ROCOF, Phase Offset Relay (POR) and Phase Angle Difference (PAD) methods. It is shown that the PRAM technique exhibits comparable performance to the others, and in many cases improves upon their abilities; in particular for systems where the inertia of the main power system is reduced, which may be the case in future systems with increased penetrations of renewable generation and HVDC infeeds.Loss of Mains (LOM) occurs when part of the utility network containing distributed generation (DG) is disconnected from the remainder of the system. Detecting LOM will become more important in the future as higher amounts of DG will be connected to increase the use of renewable energy sources, to reduce emissions and to reduce power transmission losses. In some cases, DG can be capable of supplying loads within an island and the islanded system can remain stable.;However, safety issues arise if LOM persists and, accordingly, islanded operation is not permitted in the majority of utility systems throughout the world. Wide area monitoring systems, using synchronised phasor measurements, which are beginning to play an increasing role in monitoring and control in transmission networks, may offer opportunities to improve the performance of LOM protection in distribution networks, but may require some form of communications.;A novel technique for LOM detection, using Phasor Measurement Unit (PMU) data, is described in this thesis. The technique, known as the Peak Ratio Analysis Method (PRAM), is shown to improve both the sensitivity and stability of LOM protection when compared to prevailing techniques.;The technique is based on a Rate of Change of Frequency (ROCOF) measurement from M-class PMUs, but the key novelty of the method lies in the fact that it employs a new 'peak-ratio' analysis of the measured ROCOF waveform during any frequency disturbance to determine whether the potentially-islanded element of the network remains connected to the main system or not (i.e. it detects when islanding, or loss of mains, has occurred).;The proposed technique is described and several examples of its operation are compared with three competing LOM protection methods that have all been widely used by industry and/or reported in the literature: standard ROCOF, Phase Offset Relay (POR) and Phase Angle Difference (PAD) methods. It is shown that the PRAM technique exhibits comparable performance to the others, and in many cases improves upon their abilities; in particular for systems where the inertia of the main power system is reduced, which may be the case in future systems with increased penetrations of renewable generation and HVDC infeeds
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