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A handy project : owning, perceiving, and experiencing hands
Get PDFThe purpose of this thesis is to explore the mental representation of hands in the context
of owning, perceiving, and experiencing hands. The theoretical knowledge of the thesis
is discussed in the first chapter, considering the wider concept of body representation.
The second chapter reports the data from a study exploring the relationship between the
sense of ownership of hands and motor control. The kinematic features of participants’
hands' movements were recorded using a motion analysis capture system and the
associated brain activity was recorded using a near-infrared-spectroscopy device.
Thirty-two healthy individuals participated in the study. The data show that the
embodiment of a rubber hand through touch without vision does not influence the
planning and execution of grasping actions (kinematic and brain imaging data). The
third chapter presents a study exploring the influence of disgust on the mental
representation of hands and feet in action, or motor imagery (MI). Thirty-six healthy
individuals were enrolled (different participants from the study in chapter two). The
data show that disgust enhances performance on MI tasks. The fourth chapter further
expands the knowledge of hands-related MI abilities by comparing hand-based and
foot-based MI tasks on a more implicit and explicit level (i.e. action monitoring
required to solve the task). Fifty-five healthy participants participated in the data
collection (different participants from the study in chapter three). Data show how
differences in the mental representation of hands and feet in action imagery are specific
to the degree of monitoring required, occurring only when the task is implicit; in other
words, when the degree of action monitoring decreases. In the fifth chapter, a
comparison between the data obtained in MI tasks executed in laboratory-based and
online-based settings is presented, as the pandemic led to the opportunity to explore this
aspect. This comparison shows comparable results between settings. Finally, in the sixth
chapter, a general discussion of the thesis is presented, reasoning on the limitations of
the various experiments and their impact. With the current thesis, I further expand the
knowledge on the mental representation of hands, also considering feet as opposite body
districts to hands. More in detail, my findings highlight i) that the application of the
somatic RHI does not influence motion planning and execution (i.e. maximum GA)
(owning hands), ii) that disgust influences our ability to mentally rotate hands and feet
(perceiving hands), iii) and that the mental representation of hands and feet in action
presents differences specific to the degree of action monitoring involved in solving the task (experiencing hands). The mental representation of hands is dynamic and can be
influenced differently by different factors
Street begging : a capabilities-based exploration of causal pathways, conduct, and consequences
Get PDFBegging has been a feature of towns and cities across the globe for millennia and yet
has been the explicit focus of surprisingly little scholarship. Limited understanding
regarding the reasons people beg and the impact that begging has on them has impeded
the development of effective policy responses. This study set out to add to the evidence
base regarding the causes, conduct, and consequences of begging. It has done this by,
firstly, moving beyond a focus on immediate triggers to explore factors over the life
course that contribute to begging behaviour. Secondly, the techniques and strategies
adopted by individuals when begging, and factors influencing these, were critically
examined. Finally, the research considered the consequences of engaging in begging
for the individuals who engage in it, specifically in terms of how begging enhances or
diminishes their capabilities. Employing a qualitative design that used semi-structured
interviews as the data collection method, this research analysed the insights of 26
professional stakeholders and 22 people with experience of begging across two case
study sites in England, Leeds and Lincoln. Drawing from critical realism as a
metatheoretical framework to guide the research process, the study was primarily
framed using the capabilities approach and enhanced by theoretical contributions from
scholarship on stigma. These theories highlight how the opportunities that people have
and the choices that they make in life are influenced by their experiences and the
context in which they are located.
The findings demonstrated how routes into begging lie in the clustered experiences of
compound disadvantage that can often extend back to childhood. Certain
disadvantages had a particularly corrosive effect on the capability sets of some
individuals, such as a history of insecure housing, experiences of trauma, and
problematic substance use. At the point when begging was first engaged in, individuals
were typically experiencing financial pressures from their problematic substance use
but significantly had a highly constrained capability set which limited the
opportunities available to meet their proximate needs. Begging was therefore an
activity engaged in by people because it was viewed as the least worst option to meet
these needs given the lack of viable alternatives. My analysis found that the reasons to
continue begging were at times different from the motives first driving the decision to
beg. Different people experienced unanticipated outcomes of begging such as having
a daily routine or self-reliance which made begging difficult to desist from. I devised
a new tripartite typology of begging conduct (survivalist, occupationalist, and
opportunist) to conceptualise different patterns that were influenced by different
primary motivations and had different temporal and spatial characteristics. The
patterns were also affected by the balance between the risk of negative outcomes (e.g.
abuse) and positive elements (e.g. maximising income). In addition, performative
elements were found in begging conduct with people using different props or verbal
techniques to engage with passers-by and elicit donations.
This study considered the consequences of begging concerning the six different
capabilities that were found to be impacted most, including: planning for the future;
valued social interactions and relationships; physical security; access to public and
private space; good physical health; and good mental health. Notably, the
consequences of begging were often extremely negative across all the capabilities that
were analysed, with physical health, mental health, and physical security amongst the
areas most detrimentally affected. Where positive experiences did emerge through
certain interactions or reducing isolation, they were fleeting and had no lasting or
significant impact on capabilities. Moreover, in many instances, these outcomes
fostered the continuation of begging which produced feedback loops whereby begging
further degenerated individuals’ existing and already highly constrained capabilities.
These findings have several implications for policy and practice, especially as regards
prevention through early intervention and identifying people at-risk of begging;
addressing the needs of people who beg to remove the need to begging; and
influencing public perception through less stigmatising communications campaigns
Applications of response theory to excited electronic states : metal oxide clusters and non-linear absorption in squaraine dyes
Get PDFOver the past one hundred years, an incredible range of electronic structure methods have been developed providing great insight into the quantum chemistry involved in chemical processes, including reaction pathways, structure and dynamics. The quantum mechanics of excited states provides a challenge for electronic
structure methods. Initially, this thesis inspects the ability of coupled cluster methods and time dependent density functional theory (TD-DFT) to accurately characterize the excitation energies and properties of titanium oxide clusters. By utilizing
a hierarchy of coupled cluster methods, the convergence of excited state properties in terms of systematic electron correlation has been presented along with an
examination of convergence towards the complete basis set limit. Major deficiencies were seen in second order CC2 for the clusters, attributed to a large singles
amplitudes in the Hartree-Fock orbitals. TD-DFT allowed for the study of larger
clusters, too demanding for CC. Chromium oxide clusters yielded similar results.
Having established the successes and limitations of electronic structure methods to
calculate excited state properties of transition metal oxide clusters, attention was
directed towards organic molecular systems - squaraine dyes. Squaraines, which
have an application in photodynamic therapy, exhibit interesting photochemistry
which was explored using linear and quadratic response functions in TD-DFT. The
one-photon and two-photon absorption spectra were determined in this way, while
the a posteriori Tamm-Dancoff Approximation (ATDA) was also utilized to determine two photon absorption cross sections using a three state model. Vertical
excited states from the first excited state geometry gave rise to the ESA spectra
determined by ATDA TD-DFT. To summarise, the power, scope and limitations
of electronic structure methods has been explored in two very different chemical
systems - transition metal oxide clusters and organic molecular squaraines, with
interesting results
Pore-scale modelling of low salinity/polymer enhanced oil recovery synergies
Get PDFThe study in this thesis helps to elucidate the key mechanisms affecting low salinity
waterflooding and polymer injection at the pore scale and provides insights into how these
enhanced oil recovery techniques can act synergistically to yield additional oil recovery. New
developments have been implemented in numSCAL (numerical Special Core Analysis
Laboratory) to model polymer rheology, adsorption, film flow, time-dependent wettability
alteration, snap-off mechanism etc., in addition to the existing capabilities of numSCAL.
An unsteady-state drainage model is used to study high salinity water flooding in porous media,
with results showing that the emergent flow regime is strongly influenced by several
parameters, including mobility ratio (viscosity ratio), frontal advance velocity, capillary forces,
and film flow potential, inter alia. The dynamic model is extended to study low salinity (LS)
brine flooding, polymer injection, and their various synergies. An optimal reaction rate is
identified during LS brine flooding that maximises oil recovery by shifting the flow regime
from viscous fingering to frontal advance. Polymer flooding results show that shear-thinning
polymers can lose their stabilizing effect in systems that are not strongly wetting, even at typical
reservoir flow rates. Variations in recovery due to shear-thinning are far less marked when
capillary forces are significant.
Polymer adsorption results demonstrate how polymer retention can shift a polymer flood from
a favourable displacement regime towards an unfavourable capillary fingered pattern, yielding
a loss in recovery. We also observe that the presence of initial water, while helping to provide
access for an injected phase to a larger proportion of the network, can also serve as an obstacle
to oil displacement once it exceeds a certain critical value, especially at high mobility ratios.
Positive synergy is observed when both polymer and LS brine are injected simultaneously in
secondary mode. Results show that both LS brine and polymer mechanisms can be affected by
several parameters, and a change in flow regime is found to be a key mechanism by which
these EOR methods can affect additional oil recovery. The timing of injection is found to have
a large impact on the level of success of polymer and LS brine synergies. Simulations also
demonstrate how polymer rheology and delayed LS brine wettability alteration can change the
dynamics of the polymer and LS brine synergy, determining its success as an EOR technique.
The research presented here demonstrates how several different rock/fluid properties interact
in a rather complex fashion during LS and polymer flooding and clearly shows how pore-scale simulation can increase our understanding of this complexity
Visualising fluid transport efficiency in rough fractures : towards predicting subsurface fracture flow
Get PDFSuccessful geological storage, ranging from anthropogenic waste (e.g. Carbon
Dioxide & nuclear materials) to energy (e.g. Hydrogen) storage, relies not only
upon fluid transport efficiency within geological formations but also on the ability
of overlying formations to contain injected fluids over years to millennia.
Interconnected fault and fracture systems may compromise these low-permeability geological seals, enabling fluid escape from storage reservoirs.
Identifying the degree to which faults and fractures present realistic leakage
geometries is key information for accurate risk assessment of any prospective
storage site. This thesis presents a systematic investigation into the properties
that impact single- and two-phase fluid flow in single rough fractures. We utilise
micrometre-scale imaging techniques, primarily laboratory- and synchrotron-based X-ray micro-computed tomography, to visualise and quantify the internal
geometries of 3D-printed and natural geological fractures. Fracture aperture
measurements in both materials demonstrate single fracture distributions to be
lognormal, which facilitates significant flow complexities. For two-phase flow, we
observe deviation from typical invasion percolation behaviour under capillary-dominated conditions. Quantification of the relative roughness (aperture standard
deviation/aperture mean) reveals that connected fluid invasion occurs in aperture
regions where the relative roughness ≤ 0.56. These results can inform numerical
modelling and forecasting of flow in rough fractures
Using nanopublications as a distributed ledger of digital truth
Get PDFWith the increase in volume of research publications, it is very difficult for researchers to keep abreast of all work in their area. Additionally, the claims in
classical publications are not machine-readable making it challenging to retrieve,
integrate, and link prior work. Several semantic publishing approaches have been
proposed to address these challenges, including Research Object, Executable Paper,
Micropublications, and Nanopublications.
Nanopublications are a granular way of publishing research-based claims, their
associated provenance, and publication information (metadata of the nanopublication) in a machine-readable form. To date, over 10 million nanopublications have
been published, covering a wide range of topics, predominantly in the life sciences.
Nanopublications are immutable, decentralised/distributed, uniformly structured,
granular level, and authentic. These features of nanopublications allow them to
be used as a Distributed Ledger of Digital Truth. Such a ledger enables detecting
conflicting claims and generating the timeline of discussion on a particular topic.
However, the inability to identify all nanopublications related to a given topic prevent existing nanopublications forming a ledger.
In this dissertation, we make the following contributions: (i) Identify quality
issues regarding misuse of authorship properties and linkrot which impact on the
quality of the digital ledger. We argue that the Nanopub community needs to be
developed a set of guidelines for publishing nanopublications. (ii) Provide a framework for generating a timeline of discourse over a collection of nanopublications by
retrieving and combining nanopublications on a particular topic to provide interoperability between them. (iii) Detect contradictory claims between nanopublications
automatically highlighting the conflicts and provide explanations based on the provenance information in the nanopublications. Through these contributions, we show
that nanopublications can form a distributed ledger of digital truth, providing key
benefits such as citability, timelines of discourse, and conflict detection, to users of
the ledger
Visualising fluid transport efficiency in rough fractures : towards predicting subsurface fracture flow
Get PDFSuccessful geological storage, ranging from anthropogenic waste (e.g. Carbon
Dioxide & nuclear materials) to energy (e.g. Hydrogen) storage, relies not only
upon fluid transport efficiency within geological formations but also on the ability
of overlying formations to contain injected fluids over years to millennia.
Interconnected fault and fracture systems may compromise these low-permeability geological seals, enabling fluid escape from storage reservoirs.
Identifying the degree to which faults and fractures present realistic leakage
geometries is key information for accurate risk assessment of any prospective
storage site. This thesis presents a systematic investigation into the properties
that impact single- and two-phase fluid flow in single rough fractures. We utilise
micrometre-scale imaging techniques, primarily laboratory- and synchrotron-based X-ray micro-computed tomography, to visualise and quantify the internal
geometries of 3D-printed and natural geological fractures. Fracture aperture
measurements in both materials demonstrate single fracture distributions to be
lognormal, which facilitates significant flow complexities. For two-phase flow, we
observe deviation from typical invasion percolation behaviour under capillary-dominated conditions. Quantification of the relative roughness (aperture standard
deviation/aperture mean) reveals that connected fluid invasion occurs in aperture
regions where the relative roughness ≤ 0.56. These results can inform numerical
modelling and forecasting of flow in rough fractures
Investigating the self-assembly process in supramolecular hydrogels
Get PDFSupramolecular hydrogel materials, which form via the assembly of low molecular
weight gelators, have represented a developing field of research that is showing signs of
maturing into an impactful research subject. However, a thorough understanding of the
assembly process is crucial for a more wide-spread use. Within this work, control over
the assembly mechanism in multicomponent gels and the exploration of the
thermodynamics surrounding the assembly of a light-triggered hydrogel are explored.
The assembly mechanisms operating in four multicomponent triformylphloroglucinol
based hydrogels was confirmed primarily by using small-angle neutron scattering but
with support from rheological experiments, wide angle x-ray diffraction and molecular
dynamics simulations. The effect of using different aromatic substituents was
investigated and their electronic nature was found to greatly influence the assembly.
Furthermore, two distinct gelation routes were probed which allowed the synthesis of two
different gels from the same initial components by controlling the assembly mechanism
with dynamic covalent chemistry. Distinguishing the underlying causes for changes in
the mechanisms allows for the elucidation of design principles which can, in future, be
applied to similar systems.
Control over the assembly mechanism allows for the tailoring of the gels for specific
applications with photooxidation being explored within this work. Seven visible-light
harvesting gelators were synthesised by attachment of different organic photosensitisers
and their efficiency in the production of singlet oxygen was probed using the oxidation
of methionine as a test reaction.
Taking cues from Nature, synthetic systems which operate out-of-equilibrium have
become an active area of research. This work aims to further advance this field with the
incorporation of photochemistry, employing singlet oxygen mediated reactions as a
trigger for assembly. Such reactions require only oxygen from air, light of the appropriate
wavelength and a photosensitiser, which in great part circumvents the need for toxic
reagents whilst also avoiding the build-up of waste. A meta-stable gel was formed by
designing a gelator with a singlet oxygen sensitive moiety which can be used to trigger
gelation. The equilibrium between the gel and solution state was subsequently controlled
by altering the pH and salt concentration of the system
Novel ultrafast pulse propagation dynamics in hollow-core fibres
Get PDFIn this thesis, I describe experimental and numerical work on understanding the complex nonlinear dynamics of the propagation of high-intensity laser pulses in gas-filled
hollow-core fibres (HCFs). The long interaction length and the ability to control the
dispersion and nonlinearity make HCF a great platform for exploring a wide variety of
nonlinear optical phenomena.
By employing high-order soliton dynamics, I experimentally demonstrated compression of µJ-level pulses directly from a 220 fs commercial pump laser to ∼ 13 fs in a single
stage without the need for external elements such as chirped mirrors. Moreover, I demonstrated the generation of wavelength-tunable sub-15 fs pulses through soliton-plasma interactions using the same commercial pump source. I temporally characterized the output
pulses using sum-frequency generation (SFG) cross-correlation frequency-resolved optical gating (XFROG).
Using extreme modulation instability (MI) dynamics, I demonstrated the generation
of a linearly flat supercontinuum (SC) extending from 350 nm up to 2 µm in argon-filled
broadband-guiding HCF. Moreover, I investigated the role of the Raman response on such
dynamics by using nitrogen-filled HCF. I found that due to the close rotational lines in N2,
gain suppression in the fundamental mode causes the pulse to be coupled into higher-order
modes (HOMs), which reduces the energy density of the SC.
Molecules can dissociate due to the high optical intensity of the propagating pulse, as
has been previously observed in filamentation experiments. By using molecular gases, I
was able to observe, for the first time, evidence indicating the dissociation of molecular
gases inside HCF. In particular, I observed the formation of ozone molecules inside the
fibre which is a result of the chemical reactions between the dissociated oxygen molecules
due to the high intensity of the propagating pulse. I studied the effect of such chemical
reactions on pulse propagation dynamics assisted by numerical modeling. In addition, by
using a gas mixture of molecular gases, I observed a novel phenomenon caused by the
chemical reaction between the different gas constituents
An empirical study of the temporal coherence properties of sunlight in the context of photosynthesis
Get PDFA thorough understanding of the coherence properties of sunlight will benefit both
the modelling of natural photosynthetic processes and the endeavour to design optimally performing artificial light-harvesting systems. In this thesis, we will empirically study the temporal coherence properties of sunlight in the context of photosynthesis, with a focus on the first-order and second-order degrees of temporal
coherence. We will revisit the historic calculations of sunlight coherence starting
with the black-body spectrum and then proceed to provide values for the more realistic case of atmospherically filtered light. We corroborate these values with the first
ever (to the best of our knowledge) interferometric measurements of the complex degree of temporal coherence for sunlight, from which we calculate the coherence time
of atmospherically filtered sunlight as 1.12±0.04 fs, as well as the coherence time in
a chlorophyll analogous filtered case as 4.87 ± 0.21 fs [1]. Then, we will discuss how
the photon statistics of a light beam can give us insight into the nature of the source
itself and propose a series of experiments to develop and characterize a novel light
source: an ultrafast sunlight emulator capable of reproducing the first and second-order degrees of temporal coherence of sunlight with ultrafast, broadband pulses.
Finally, we will model partially coherent optical excitations of two-level systems and
study the role that the phase of the driving field plays in the population dynamics
of the two-level system and coherence time of the excitation source. The results
of this thesis will act as a useful reference for the community when discussing the
temporal coherence of sunlight, as well as a guide toward the development of an
ultrafast sunlight emulator for quantum biology
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