2,104 research outputs found
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 āend of lineā) 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 ā the intervening spaces - of a network when the location is unknown
Ambulance Service 2030: the Future of Paramedics
Some innovations are termed ādisruptiveā, 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 āhallmarksā. 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 ātraditionalā 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 āHorizon Scanningā in an attempt to detect āsignalsā, themes and trends in relation to newly emerging ācompetitorsā 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 āFranco-Germanā model/System (FGM/S). Hitherto, the model of provision in the UK had followed the āAnglo-Americanā 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 shouldnāt 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 ābackward step for womenā, or āanother form of victim blamingā, 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 āComparative Perspectives on Transportation Securityā, 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; ācan we adequately cover multimodal transport for both passenger and freight transport in a single volume?ā (p292). That they managed to achieve this is a feat in itself, although as they acknowledge āthis necessarily limited coverageā although I would argue not to the bookās 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
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