Diffusive optical tomography in the Bayesian framework

Many naturally-occuring models in the sciences are well-approximated by simplified models, using multiscale techniques. In such settings it is natural to ask about the relationship between inverse problems defined by the original problem and by the multiscale approximation. We develop an approach to this problem and exemplify it in the context of optical tomographic imaging. Optical tomographic imaging is a technique for infering the properties of biological tissue via measurements of the incoming and outgoing light intensity; it may be used as a medical imaging methodology. Mathematically, light propagation is modeled by the radiative transfer equation (RTE), and optical tomography amounts to reconstructing the scattering and the absorption coefficients in the RTE from boundary measurements. We study this problem in the Bayesian framework, focussing on the strong scattering regime. In this regime the forward RTE is close to the diffusion equation (DE). We study the RTE in the asymptotic regime where the forward problem approaches the DE, and prove convergence of the inverse RTE to the inverse DE in both nonlinear and linear settings. Convergence is proved by studying the distance between the two posterior distributions using the Hellinger metric, and using Kullback-Leibler divergence

Interstitial crime analysis

Crime on public transport can be very difficult to analyse. 'Stealth crimes' like pick-pocketing present a particular challenge because victims often have an imprecise knowledge of the location and time of the offence. In this scenario crime has typically been recorded as happening at the reporting station (often at the ‘end of line’) which skews any analysis of the collective crime locations. Interstitial crime analysis (ICA) is a technique which overcomes this problem and improves the estimation of the spatial distribution of crime on networks when the exact location of offences is unknown. Based on the aoristic analysis technique (devised to estimate the temporal distribution of crime when only a time period is known), ICA is used to estimate the location of crimes in the interstices – the intervening spaces - of a network when the location is unknown

Ambulance Service 2030: the Future of Paramedics

Some innovations are termed ‘disruptive’, a designation that is normally applied to technology; examples include computers, digital cameras, and mobile phones. The term can also be applied to groups of workers, particularly if they are able to offer specific technical capabilities within a market at lower cost, but broadly equal and effective to that offered by traditional products or services. Paramedics could be described in this way and are a newly professionalised group, with distinctive capabilities in terms of responding to the needs of not just the acutely ill and injured, but increasingly those patients with undifferentiated non-life- threatening conditions, which increasingly make up the bulk of 999 call demand. The key to their transition from an artisan, skilled worker to professional status is the acquisition of certain ‘hallmarks’. Perhaps the most important of these is the completion of more prolonged education that affords the opportunity to graduate with enhanced decision-making and other clinical skills in order to meet the needs of the full spectrum of patients in the pre-hospital setting. Paramedics were surveyed to determine how they rated their ‘traditional’ preparation and to establish what their attitudes were to a more educationally based approach. Paramedics themselves proved to be realistic regarding shortcomings in established training and education systems, while also being strongly motivated to learn more within a higher education setting, particularly if this additional effort would result in being able to offer a wider range of care to their patients. During the study, major changes in the health care environment and the role of the Ambulance Service took place, leading to a requirement to undertake a second phase of research. This took the form of ‘Horizon Scanning’ in an attempt to detect ‘signals’, themes and trends in relation to newly emerging ‘competitors’ to the paramedic role. These included nursing, new practitioners and most critically, the rapidly emerging medical sub-speciality of pre-hospital care, staffed by medical personnel on a pattern found specifically in some European countries, sometimes termed the ‘Franco-German’ model/System (FGM/S). Hitherto, the model of provision in the UK had followed the ‘Anglo-American’ model/System (AAM/S), approach, with paramedics providing direct patient care in the field and medical staff largely involved in medical oversight, teaching, clinical governance and other higher level roles. As part of this research, the evidence base for change was examined and consideration given to the factors that might help clarify what the likely situation could be in 2030 in respect of ambulance services, pre-hospital care and paramedics. This future is uncertain, but factors have been identified that would militate in favour of one or other model prevailing, with close links established between educational preparation, system design, career structure and the continuance of the professionalisation process favouring paramedic progression. However, other factors, most specifically professional power, the absence of a clear evidence base and an apparent reluctance to clearly acknowledge this in some respects, lead to the conclusion that the future of pre-hospital care remains uncertain and contested, but also potentially amenable to a well-directed influencing strategy

Why we shouldn’t dismiss the idea of women-only carriages

After Labour Party leadership candidate Jeremy Corbyn raised the idea of women-only carriages on trains the idea has been variously described as a “backward step for women”, or “another form of victim blaming”, and even compared to apartheid. The harassment women experience in public spaces and what to do about it is a highly emotive subject, so why dismiss the idea outright

Book Review: Multimodal transport security: Frameworks and policy applications in freight and passenger transport: Joseph Syzliowicz, Luca Zampari, Genserik Reniers and Dawna Rhoades (editors) Edward Elger Publishing, Chelterhan, Uk and Northampton, MA, USA, ISBN 978 1 78347 481 3

This edited collection is part of the series ‘Comparative Perspectives on Transportation Security’, also edited by Syzliowicz and Zampari. The previous book in this series (2014) focussed on maritime security. This edited collection attempts to address multimodal transportation and consists of 19 chapters, predominantly split into two sections: multimodal freight transportation security, and multimodal passenger transportation security. Each of these sections is then subdivided into two further subcomponents. For firstly freight, and secondly passenger security, the book repeats the same structure. A series of chapters are presented that examine themes and frameworks, and then a second set of chapters examine policy applications from the perspective of different international countries. This is a highly ambitions collection, and indeed as the editors asked themselves; ‘can we adequately cover multimodal transport for both passenger and freight transport in a single volume?’ (p292). That they managed to achieve this is a feat in itself, although as they acknowledge ‘this necessarily limited coverage’ although I would argue not to the book’s detriment

Investigations into the kinetics of nitrification

Abstract unavailable please refer to PDF

Optimisation of a moving platform vehicle simulator for vehicle handling experiments

This thesis discusses the optimisation of motion platform simulators and was motivated by Loughborough University's acquisition of a low cost six strut moving platform vehicle simulator. Historically, we see that automotive vehicle simulators are more generally used for human factors experiments that examine driver behaviour during low severity manoeuvres or short events e.g. obstacle avoidance. The purpose of this thesis is to examine the potential for the simulator to be used for vehicle handling experiments where the vehicle is free to explore the limits of the vehicle for sustained periods of time. This research has a significant emphasis on vehicle handling models. In particular, we examine data acquisition systems and testing methods before investigating potential optimisation and identification techniques for estimating vehicle model parameters that have the potential to be implemented on the simulator. Here we examine the possibility of producing high quality vehicle models within a short space of time with a view to rapid identification of different types of vehicle directly from vehicle testing. This includes the data acquisition process and addresses the significance of the sensors and equipment used to measure the vehicle states and the importance of the recorded vehicle manoeuvres and test track characteristics. The second phase was carried out once the simulator was installed and functional. Clearly, the simulator is a piece of experimental equipment and as with any engineering experiment, the equipment should be well understood. Consequently, the accuracy to which it adheres to the real world, i.e. its fidelity, is assessed by investigating the simulators capabilities and limitations and is achieved by analysing the raw performance of the motion platform and conducting driver-in-the-Ioop experiments; this work proves valuable as it is used to optimise how the motion platform responds to vehicle dynamics and provides the motivation behind conducting a driver-in-the-Ioop handling experiment for the final section of this thesis. Here, the simulators potential to be used as a tool to assess race car driver skill is investigated. After conducting various tests in the simulated and real world, the correlation between the subjects simulated and real world performances are used to critically assess the simulators performance and draw conclusions concerning its future potential for handling based research. This thesis shows it possible to use an Inertial GPS Navigation System for capturing vehicle data to good effect and describes how a comprehensive set of new vehicle dynamics measurements can be collected and used for model tuning and optimisation within a relatively short space of time (approximately one day). The work presents substantial evidence that shows how dominant the influence of steer ratio and toe compliance is on the accuracy of the handling models and that they are a likely source of modelling errors. The importance of vehicle slip angle measurement is a particular point if of interest and is examined concurrently with the driving manoeuvres, where some guidelines for test methodology and data collection are established. A novel identification process is also presented with the Identifying Extended KaIman Filter. It has been shown possible to identify separate front and rear tyre models as well as a single tyre model. The thesis also describes the relative importance of motion for vehicle simulators that are to be used for handling based experiments. It appears more valuable to emulate only those vehicle motions that are within the platforms capabilities and limitations in a quest for quality over quantity. Finally, this work demonstrates the simulators potential to be used as tool to evaluate race car driver skill, which also fundamentally assesses the fidelity of the simulator. This is achieved by examining the correlation between a simulated and real world experiment, where we see a positive correlation which indicates high fidelity. Further analysis shows the importance that adequate driver training is being administered before beginning experimentation

An empirical calibration to estimate cool dwarf fundamental parameters from H-band spectra

Interferometric radius measurements provide a direct probe of the fundamental parameters of M dwarfs, but is within reach for only a limited sample of nearby, bright stars. We use interferometrically-measured radii, bolometric luminosities, and effective temperatures to develop new empirical calibrations based on low-resolution, near-infrared spectra. We use H-band Mg and Al features to derive calibrations for effective temperature, radius and log luminosity; the standard deviations in the residuals of our best fits are, respectively, 73K, 0.027Rsun, and 0.049 dex (11% error on luminosity). These relationships are valid for mid K to mid M dwarf stars, roughly corresponding to temperatures between 3100 and 4800K. We apply our calibrations to M dwarfs targeted by the MEarth transiting planet survey and to the cool Kepler Objects of Interest (KOIs). We independently validate our calibrations by demonstrating a clear relationship between our inferred parameters and the absolute K magnitudes of the MEarth stars, and we identify objects with magnitudes too bright for their estimated luminosities as candidate multiple systems. We also use our inferred luminosities to address the applicability of near-infrared metallicity calibrations to mid and late M dwarfs. The temperatures we infer for the KOIs agree remarkably well with those from the literature; however, our stellar radii are systematically larger than those presented in previous works that derive radii from model isochrones. This results in a mean planet radius that is 15% larger than one would infer using the stellar properties from recent catalogs. Our results confirm those of previous in-depth studies of Kepler-42, Kepler-45, and Kepler-186.Comment: Accepted to ApJ. Tables 4 and 5, and machine readable versions of Tables 5 and 7 are available in the ApJ journal articl

Resonance enhanced turbulent transport

The effect of oscillatory shear flows on turbulent transport of passive scalar fields is studied by numerical computations based on the results provided by E. Kim [Physics of Plasmas 13, 022308 (2006)] . Turbulent diffusion is found to depend crucially on the competition between suppression due to shearing and enhancement due to resonances, depending on the characteristic time and length scales of shear flow and turbulence. Enhancements in transport occur for turbulence with finite memory time either due to Doppler or parametric resonances. Scalings of turbulence amplitude and transport are provided in different parameter spaces. The results suggest that oscillatory shear flows are not only less efficient in regulating turbulence, but also can enhance the value of turbulent diffusion, accelerating turbulent transport