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Electron transport through organic molecules is a process fundamental to life and plays a central role in the emerging field of molecular electronics. This thesis presents an investigation of electron transport through molecular systems from the perspective of full counting statistics. An extension of a Markovian counting statistics framework to a non-perturbative setting is presented which allows for an exact treatment of the phonon bath. This framework is applied to a theoretical photocell device inspired by the photosystem II reaction centre. It is demonstrated that the asymmetric coupling of excitation and charge transfer states to a structured spectral density rather than a smooth low energy background has the effect of reducing the output current along with an associated reduction in the current fluctuations. The insights gained from this are discussed in terms of design principles for pigmentprotein complexes used in nano-electronic devices and their relevance for biological function in vivo. Finally, the asymmetric coupling of excitation and charge transfer states to their vibrational environment is investigated more closely through the dynamics of a dimer model and the effect of the output current statistics of a prototype photocell.

This thesis concerns quasi-two-dimensional (quasi-2D) ultracold Fermi systems with short range interactions. Here, quasi-2D geometries are those that lie between two- and three-dimensions. We study few- and many-body systems composed of two or three distinguishable species of fermions. Of principle interest are the bound states that form in these systems and how these bound states are affected by the quasi-2D geometries. In the first research chapter, we focus on the two-dimensional (2D) regime of quasi- 2D. We begin by developing an effective 2D model of this 2D-like geometry. We use this model to analyse a Fermi system consisting of three fermionic species with equal interactions between all distinguishable pairs. Starting with the few-body problem, we show that there is always a three-body bound state (trimer) in the effective 2D model and that these 2D trimers are stable. This is notably different from the extremely unstable ‘Efimov’ trimers found in three-dimensional (3D) systems. Using a low-density expansion and a variational approach, we investigate the fate of the 2D trimers as the system’s density is increased from the three-body limit to the many-body limit. We find that remnants of trimers can persist in the form of strong three-body correlations in the many-body system. In the second research chapter, we analyse a realistic experimental system of three distinguishable fermions confined to quasi-2D. We develop a model that goes beyond the previous chapter in two regards. Firstly, we allow for unequal interactions between the pairs of fermions. Secondly, we use a full quasi-2D model that is not specific to the 2D-like regime. With this general model, we use the scattering and confinement parameters from experiments on ultracold 6Li atoms to calculate the trimer spectrum across the dimensional crossover from 2D to 3D. We show that one state smoothly evolves from an unstable 3D-like trimer to a 2D-like trimer as the attractive interactions are decreased. We furthermore compute the trimer wave function and quantify the stability of the trimer with respect to three-body recombination by determining the probability that three fermions approach each other at short distances. Our results indicate that the lifetime of the trimer can be enhanced by at least an order of magnitude in the quasi-2D geometry. This opens the door to realising long-lifetime trimers in ultracold gas experiments and furthermore, the many-body state of trimers predicted in the preceding chapter. vii In the final research chapter, we examine an alternative approach to accessing quasi-2D geometries by using a system of coupled 2D planes. We study the two-component Fermi gas in this geometry, as a preliminary to studying the three-component gas. We find that the interplanar coupling can be tuned to drive a dimensional crossover from 2D to 3D. We study the effect of this dimensional crossover on the two- and many-body systems. In general, we find that two-body correlations are strengthened by weakening the coupling between 2D planes. In the many-body system, we use mean-field theory to find that the critical temperature of pairing is increased by weakening the coupling between 2D planes. This represents a first step towards a more general representation of quasi-2D geometries, namely: A system of coupled quasi-2D planes.

Methane is one of the most important greenhouse gases in the Earth’s atmosphere. The global growth of methane therefore presents a significant challenge for the scientific community. Global measurements currently provide high quality regional estimates of methane concentration, but little information on the origins of atmospheric methane. This thesis presents a range of studies aimed at determining the capability of current Earth Observation (EO) satellites for identifying methane sources and their origins on a global scale. Two key areas are studied: 1) source and seep detection using high spatial and temporal resolution measurements; and 2) identification of the origins of these sources through the measurement of the ratio of the main methane isotopologues 12CH4 and 13CH4. This ratio, otherwise known as δ13C, can be employed to identify the nature of a methane source, whether it originates from a biogenic source (e.g. marshlands) or abiogenic (industrial bi-products). The application of residual radiance and information content analysis techniques show that total column measurements of δ13C are feasible using the GOSAT-TANSO-FTS. Initial synthetic studies suggest total column retrieval errors of < 20% or up to 3 ppbv can be anticipated on 13CH4. High spatial and temporal resolution data products from the satellites GOSAT and the Infrared Atmospheric Sounding Interferometer (IASI) are used to identify point sources of high methane output on the Earth’s surface. Measurements are focused on three known emissions points, and both instruments show significant capability for “hot-spot” detection, albeit with significant bias between the instruments. One of the previously published sources with SCIAMACHY is found to be missing in the GOSAT and IASI retrievals. Assessments are made into the potential error sources of these instruments, which show that although the current EO satellite IASI and GOSAT can potentially be powerful tools, careful error analysis must be made before making any definitive conclusions.

The complexity of multidisciplinary projects requires that many specialities and disciplines work together. In rail infrastructure projects, the term 'systems engineering (SE)' is being widely used, yet it is still loosely defined. This PhD thesis proposes the use of a Disciplinary Breakdown Structure (DBS), an approach that better integrates SE as it is currently understood with traditional project management (PM) to make PM more efficient. A review of PM, SE and their relationship, particularly in the rail sector, identified gaps in performance, the most significant of which is a lack of integration between the SE and PM activities. Case study material was examined and a survey was conducted. The results highlighted the lack of consensus and consistency of the definition of SE and its application by project practitioners at various levels. Interface management (IM) was identified as a key factor contributing in project failure or success. IM was reviewed in the context of SE and PM, and existing methods and solutions were examined. The DBS as a new solution, was developed and introduced to improve the IM life cycle from definition to closure. This solution is based on industry discipline sectors (in this case, the rail sector) and therefore it is independent from project specific requirement. Exploring more detail of the DBS revealed its capability in integrating SE and PM more generally. The DBS is a modular solution (with a potential to become an industry standard) that provides a basis for the rapid development of project-bespoke management systems, improving PM efficiency by saving time and resources. The approach has been tested in two major rail project case studies in the UK and one in Canada and the results, benefits, constraints and the areas of improvements are discussed in more detail.

In this thesis I show how large galaxy surveys, in particular the study of the properties of galaxies, can shed light on gravitational wave sources and dark matter. This is achieved using the latest data from the Dark Energy Survey, an on-going 5000 deg2 optical survey. Galaxy properties such as photometric redshifts and stellar masses are derived through spectral energy distribution fitting methods. The results are used to study host galaxies of gravitational wave events and how light traces dark matter in galaxy clusters. Gravita- tional wave (GW) science, and particularly the electromagnetic follow up of these events, is transforming what had never been seen into a new astronomical field able to unveil the nature of cataclysmic events. Identifying the galaxies that host these events, and es- timating their redshift, stellar mass, and star–formation rate, is crucial for cosmological analysis with gravitational waves, for follow up studies and to understand the formation of the binary systems that are thought to produce observable gravitational wave signals. This thesis describes how the host matching is implemented within the DES–GW pipeline and how observations of NGC 4993, the galaxy host of the event GW170817, provide important information about possible formation scenarios for binary neutron stars. In particular, we find that NGC 4993 presents shell structures and we relate their formation to the binary formation. The same galaxy properties are used to derive an observable mass proxy for galaxy clusters. I show that this mass observable correlates well with the total mass of clusters, which is mainly composed of dark matter. It can therefore be used for cosmological studies with galaxy clusters. The measurement of stellar–to–halo mass relations in clusters provides insights on the connection between the star content and the total matter content in clusters, and how this evolves over cosmic time.

This thesis sets out to examine the ways in which actors sitting within local infrastructure organisations (LIOs) consider, construct and respond to ideas of legitimacy against the backdrop of a shifting institutional environment that increasingly favours charging front line organisations (FLOs) for support services that were previously provided free at the point of use. It employs an institutional lens to explore the linkages between actors, legitimacy and a shifting institutional narrative from an actor level perspective, providing insight into the ways in which actors' worldviews of what is - and what is not - legitimate are shaped, and how such worldviews then play out in practice. At a theoretical level, the research advances knowledge in respect of bringing about an understanding of the contemporary changes happening within LIOs in relation to charging for services, particularly from an actor level perspective. At a practical level, the research serves to inform practitioners both within LIOs, and within organisations more broadly, of the frames through which actors consider whether a change (such as a new policy or new strategic direction) may or may not be legitimate, and the ways that those actor worldviews then shape the behaviours of actors, or groups of actors, in practice. The thesis presents information drawn from a multi-sited ethnography, conducted across four LIOs over a six month period, with six weeks spent at each site. The findings are presented through a typology of thirteen distinct actor worldviews of legitimacy, which are informed by the dominant value set of each actor type, and played out through the employment of ten separate rhetorical strategies, used to argue for their preferred worldview. The typology serves to underpin an eight stage process of actor legitimacy formation and influencing, which shows the stages through which actors consider, construct and respond to ideas of legitimacy at times of institutional shift. The key contribution to knowledge arising from the research is embedded in how considerations of legitimacy play out at an actor level across LIO settings, in specific relation to actor consideration of and responses to contemporary changes with respect to institutional shifts towards the favouring of chargeable support services. The eight stage process underpinning this contribution also contributes to understandings of how legitimacy plays out at the actor level per se, and how actors seek to shape their institutional environment at times of shifting institutional narratives. It does this by developing understanding of the ways in which actors use their worldviews of legitimacy in a bid to further the interests that they believe to be legitimate within their institutional environment. This in turn contributes to debates surrounding how legitimacy plays out at the actor level and how actors consider, construct and respond to ideas of legitimacy. Further, the typology of actor worldviews underpinning the eight stage process contributes to current understandings of legitimacy both by adding an actor level perspective to the currently available typologies of legitimacy, and by contributing four legitimacy types that are not believed to exist in current literature. These four legitimacy types focus on legitimacy as viewed through a focus on strategy; legitimacy that is opportunistic in nature; legitimacy relating to leadership of the sector or industry, and legitimacy that relates to advancing practice.

Controlling atmospheric levels of greenhouse gases is required to mitigate the effects of anthropogenic climate change. A promising solution to reduce emissions of carbon dioxide (CO2) to the atmosphere is carbon capture and storage (CCS). These technologies comprise methods to isolate CO2 at its point of production, and inject it underground into a suitable geological formation for long-term storage. While CCS has been demonstrated at a number of sites across the world, there are challenges involved in monitoring the fate of CO2 in the subsurface after its injection. Muon tomography has been suggested as a monitoring technique that can compliment other methods such as repeat seismic surveys. It is proposed that muon detectors, which can be deployed in underground boreholes beneath a storage site, will measure changes in muon intensity caused by variations in the density distribution of the overburden due to the presence of CO2. In this thesis, muon simulations of a geological repository are presented to determine the feasibility of muon tomography for monitoring carbon storage sites. In addition, simulations of the local radioactive backgrounds for borehole detectors have been developed to understand their setup and operating conditions. It is found that the constant injection of CO2 into a typical storage formation leads to changes in density that are observable as a statistically significant change in muon intensity within 50 days of data taking. While cosmic-ray muons provide a signal for muon tomography, they are an unwanted background for underground experiments searching for rare physics events. Backgrounds from radioactivity in the vicinity of a sensitive detector may also obscure potential signals and limit sensitivity. Using the models developed for muon tomography simulations, the muon-induced and laboratory backgrounds for the LUX-ZEPLIN (LZ) dark matter experiment have been characterised. It is found that the rate from these sources is subdominant to internal detector backgrounds.

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Presented herein are results of optical studies with emphasis on the Raman response, providing significant contribution to the knowledge of the field. In Mox W(1−x) S2 , confirmation of the behaviour of the excitonic properties is made. Raman measurements performed in this system allow investigation with unprecedented resolution, highlighting deviations in the high frequency A1g optical phonon mode from theoretical predictions, and previous experimental studies. In the low frequency, data confirms the trends in the shear and breathing interlayer modes in alloys between WS2 and MoS2 are well described by the modification in the square density. Resonant excitation for [Mo] < 0.4, highlights new evidence for the understanding of the hitherto unexplained ‘Peak X’ resonant feature. Diverse indium-selenium compounds isolated by novel means are studied. The ULF Raman modes of PDMS exfoliated InSe are documented for the first time, demonstrating the ε-phase with ABA stacking, with flake of thickness N manifesting (N − 1) shear modes owing to resonant excitation of few layer samples. InSe flakes encapsulated in hexagonal boron nitride manifest different stacking orders to those of PDMS exfoliated InSe, and were found to have significant contamination, with crystalline degradation of the monolayer flake, and peaks corresponding N2 & O2 rotational modes present. In2Se3 films grown epitaxially on GaSe display substrate-selective polymorphism, where α-, β-, & γ- phases are identified, in addition to regions of InSe. Laser photo-annealing is shown to drive a phase change from the groundstate β → α phase, which is against the thermodynamic gradient. MoSe2/WS2 twisted hetero-bi-layer structures are studied, where shear modes showing a linear softening from AA′ stacking towards the AB at 60° indicating reduced interlayer coupling, as expected from the difference in interlayer spacing of AA′ and AB ordering. High frequency modes in the heterobilayer also demonstrate some sensitivity in the relative angle, and are analysed in detail.