The ANtarctic Impulsive Transient Antenna (ANITA) experiment is a balloon-borne array of radio antennas designed to search for ultra-high energy neutrinos by observing the Antarctic ice sheet for radio emission that is expected to arise as a result of the neutrinos’ interaction. ANITA is further able to detect radio emission that arises when ultra-high energy cosmic-rays interact in the Earth’s atmosphere. The second flight of the experiment, ANITA-2, took place in 2008-09 over 31 days. This thesis describes an analysis of the ANITA-2 dataset and presents results from searches for ultra-high energy neutrinos and cosmic-rays. No statistical evidence of emission from neutrino interactions is observed, with two candidate events discovered on a background of 1:13 \pm 0:27. A limit on the diffuse flux of ultra-high energy neutrinos is presented, further model-independent and model-dependent flux limits on selected active galactic nuclei are calculated. Four isolated and one non-isolated cosmic-ray candidates are discovered. The identity of the isolated candidates as cosmic-ray-induced radio emission is confirmed through correlation between observed and expected emission polarisation.

At the outset of this study, we implemented a series of axisymmetric, time-invariant Galactic potential models, by coding these numerically. With these potentials, we carried out a series of investigations in Galactic dynamics, related to Globular Cluster disk impacts, Open Cluster birth scenarios, and Planetary Nebula trajectories. The first of these studies relates to the crossing of the Galactic disk by a Globular Cluster to examine whether these could produce star formation due to gravitational focussing or compression of disk material. We report on simulations of the effect on disk material which reveal that the crossing can sometimes cause local gravitational focussing of disk material. This adds to the strong compression that can result from the shock wave generated by a GC disk crossing examined by Levy (2000). The main thrust of this first study is a search for any remnants of disk crossings by Globular Clusters. Using the gravitational potential of the Galaxy to locate the position of the most recent crossings of a subset of fifty-four Globular Clusters reveals that systematic errors and uncertainties in initial conditions limit the scope for unequivocal identification. From the subset of fifty-four, six possible search sites with the best constraints are retained for further scrutiny. Three of the six potentially promising search areas in the disk relate to Globular Clusters NGC 3201, 6397 and NGC 6838, for which we cannot rule out some observed star associations observed nearby as being remnants. The three other of the six areas are too large to provide meaningful identification of remnants. Also, a possible remnant (Open Cluster NGC6231) is shown not to be due to Globular Cluster impact, contrary to a previous report. In a more wide-ranging screening of one hundred and fifty-five Globular Clusters we identify which Globular Clusters are compatible with being responsible for the formation of any of the Galaxy’s five most prominent Star Super Clusters. For the second study, we considered six mechanisms so far proposed to account for the Galactic disk heating. Of these, the most important appear to be a combination of scattering of stars by molecular clouds and by spiral arms. We study a further mechanism, namely the repeated disk impact of the original Galactic Globular Cluster population up to the present. We find that Globular Clusters could have contributed a small fraction of the current vertical energy of the disk, as they could heat the whole disk to σz = 5.5kms−1 (c.f. the observed 18 and 39 kms−1 for the thin and thick disks respectively). We find that the rate of rise of disk heat (α=0.22 in σz ∼ tα with t being time) from GC heating, is close to that found for scattering by molecular clouds. Our third investigation relates to the Galactic population of Open Clusters which provides an insight into star formation in the Galaxy. The Open Cluster catalogue by Dias et al.(2002b) is a rich source of data, including kinematic information. Using this large sample we carry out a systematic analysis of 481 Open Cluster orbits, using parameters based on orbit eccentricity and separation from the Galactic plane. These two parameters may be indicative of cluster origin, and we find them to be correlated. We also find them to be correlated with metallicity, another parameter suggested elsewhere to be a marker for origin, in that high values of any of these two parameters generally indicate a low metallicity ([Fe/H] Solar< −0.2 dex). The resulting analysis points to four Open Clusters in the catalogue potentially being of extra-Galactic origin by impact of high velocity clouds on the disk: Berkeley21, 32, 99, and Melotte66, with a possible further four due to this origin (NGC2158, 2420, 7789, IC1311). A further three may be due to Galactic Globular Cluster impact on the disk i.e. of internal Galactic origin (NGC6791, 1817, and 7044). We show that clusters with highly eccentric orbits and thus low metallicity move in and out radially in the disk, thus transporting low metallicity radially across the disk. This led us to undertake observations at the WHT (November 2010), to assess the metallicity of the top six candidates with the most eccentric orbits. In a fourth study, we use the orbit sizes to constrain parameters related to the core star of Planetary Nebulae. Firstly, we map the orbit of the core of Sh-2-216 and observe from its vertical extent, that this is a thin disk object. Secondly, we plot the orbits of the core of Sh-2-68 for various values of its current distance, this being a parameter affected by a large uncertainty, and we fix the maximum current distance to at most 600pc; any larger value would lead to an unbound orbit. In a final study we examine cases where the Galactic potential is not axisymmetric (due to spirals), and cases where the axisymmetric potential varies in time, due to Galactic evolution (due to mass increase). The non-axisymmetric features allow us to examine the extent of radial stellar mixing in the disk, and we find that stars can be ejected from their Keplerian disk orbit up to an altitude of several kpc, and this may contribute to disk heating discussed above. This underlines the role of non-axisymmetric features in Galactic evolution. Lastly, we investigate the impact on stellar orbits of a Galaxy whose mass increases with time, and find that large effects can be expected, but not for orbits occurring within the last ∼10 Myr or ∼1 Gyr. We conclude the work by suggesting further model improvements and their applications.

NEMO 3 is a double beta decay experiment situated in the Fréjus tunnel which runs between France and Italy. If neutrinoless double beta decay is observed it will prove the neutrino is a Majorana particle and may potentially become the most sensitive method of measuring the absolute neutrino mass. It would also have huge implications for not only particle physics, but also nuclear physics, astrophysics and cosmology. The study of two-neutrino double beta decay gives us a better understanding of the nuclear models used to calculate the nuclear matrix elements, which are so important in extracting new physics parameters from the neutrinoless double beta decay search. The purpose of this thesis is primarily to report on the measurement of the two neutrino double beta decay of two isotopes, ^{100}Mo and ^{48}Ca, currently inside the NEMO 3 detector. The double decay of ^{100}Mo to the O^{+}_{1} excited state of ^{100}Ru is studied as well as the double beta decay of ^{48}Ca to the ground state of ^{48}Ti. The two neutrino half-life measurement for ^{100}Mo is found to be T^{2\upsilon}_{1/2}(O^+\rightarrow O^{+}_1}) = 5.70^{+1.15}_{-0.82} (stat) \pm 0.77 (syst.) \times 10^{20} yrs. This being the first result where all the final states have been measured. For ^{48}Ca, the two neutrino half-life is T^{2\upsilon}_{1/2}(g.s. \rightarrow g.s.) = 4.44^{+0.49}_{-0.40}(stat.) \pm 0.29 (syst.) \times 10^{19} yrs, which is the worlds most accurate measurement of this decay process. A limit on the neutrinoless double beta decay of ^{48}Ca has also been obtained.

The formation of a cancer is an evolutionary process. A somatic cell may acquire an (epi)-mutation that gives it a growth advantage relative to its neighbours. Progression to cancer occurs as cells in the resulting mutant clone acquire additional mutations, which may also confer a selective advantage. This thesis investigated the expansion of mutant clones both prior to, and during, tumour growth. First, the clonal expansion of a mutant lineage within a stem cell niche was considered. The behaviour of mutant germline stem cells in the Drosophila testis, a remarkably well-characterised niche, was investigated. A model was developed which identified stem cell phenotypes that were selectively advantageous in the niche. Crypt fission is thought to be the primary mechanism of clonal expansion in the gut. A model of crypt fission was developed, which was used to estimate the frequency of fission events in the normal human colon. Crypts were found to divide infrequently, and fission was predicted to decrease the likelihood that a mutant clone would be lost from the gut. Next, the expansion of mutant clones during the initial growth of colorectal adenomas was considered. Individual crypts were micro-dissected from small adenomas, and the mutation status of the APC and K-ras genes in each crypt was determined. Combining this information revealed how the adenoma had formed. It was found that K-ras mutations may have occurred earlier in tumorigenesis than had been previously established. Last, the effect of clonal expansion on the genetic heterogeneity in a cancer was examined. A model of microsatellite slippage during cancer growth was developed. The model showed that clonal expansion during cancer growth, coupled with a low rate of somatic mutation, can generate non-negligible amounts of genetic diversity. This suggested that there was little evidence for a low-level microsatellite mutator phenotype in colorectal cancers.

In the short evolutionary time since the human-chimpanzee divergence, approximately 6.6 million years ago, humans have acquired a range of traits that are unique among primates. These include tripling brain size, enhanced cognitive abilities, complex culture, descended larynx structure that enables spoken language, longevity, specific diseases, inferior olfaction, and (in some human populations) adult lactase persistence. These traits were likely to have evolved through various genomic mechanisms, among them gene duplications and gene-culture co-evolution. Several studies have estimated the dates for some of these human lineage genomic events. However, no study to date has performed a genomewide estimate of the dates of all human gene duplications. Moreover, as many of these traits were likely to have evolved via gene-culture coevolutionary mechanisms, investigating the evolution of one of these human-specific traits – lactase persistence – provides a model example for in-depth future investigations of specific human phenotypes. In this study I have investigated an important class of human-specific genomic events – gene duplications (otherwise known as human inparalogues). I have developed a new bioinformatics approach for detecting human lineage-specific inparalogues and the duplication dates for those genes. I show that human-specific inparalogues are non-randomly distributed among biological function classes, and their duplication event dates are non-randomly distributed on a timeline between the date of the human-chimpanzee split and the present. I have also investigated the evolution of the human-specific polymorphic trait – lactase persistence. I have performed a worldwide correlation analysis comparing frequency data on all currently known lactase persistence-associated alleles and the distribution of the lactase persistence phenotype in different human populations. I have also performed a gene-culture co-evolution analysis, employing spatially explicit simulation and Approximate Bayesian Computation to condition simulations on genetic and archaeological data, in order to make inferences on the evolution of lactase persistence and dairying in Europe.

This thesis investigates the properties of entanglement in strongly correlated quantum systems, more specifically that between regions of a many-body system which may be separated spatially giving rise to a part of the system which is disregarded. The focus of the first part of this thesis is the response of a collection of spins, arranged on a one dimensional lattice, to a global quench, i.e. a rapid change in the interaction characteristics. Such a quench is seen to produce a significant amount of entanglement between distant spins. The robustness of the scheme towards random disorder is detailed and it is shown that the entanglement is sufficiently high to be distilled into almost pure Bell pairs. In a similar model system, it is explored how a von Neumann measurement with post-selection (i.e., discarding certain measurements based on the outcome) performed locally on two possibly well separated regions of spins, may give rise to a pure and entangled state of these regions, assuming the system is in its ground state. Later chapters are concerned with entanglement between noncomplementary groups of spins at quantum critical points, a situation where at zero temperature quantum fluctuations become pronounced. For spin chain models it is observed that this entanglement (as measured by negativity) assumes a finite value depending only on the ratio of the size of the regions to their separation and is further seen to be universal, i.e. independent of the microscopic details of the interaction. Universality of this form of entanglement is finally explored in a collective spin model. By casting the problem into the language of a few bosonic modes a closed form expression for the negativity in the thermodynamic limit for the entire phase diagram of the model is derived. At the quantum critical point this measure is explicitly universal in the aforementioned sense.

A sample of W \rightarrow ev (W \rightarrow \mu v) and Z^0 \rightarrow e^+e^- (Z^0 \rightarrow \mu^+\mu^-) events recorded by the CDF detector for pp- collisions at \sqrt(s-hat) = 1:96 TeV with a total integrated luminosity of 2.3 fb^-1 are used to evaluate the systematic uncertainty in the determination of the W boson mass arising from uncertainties in the parton distribution functions and higher-order QCD effects. The systematic contribution of PDFs is determined to be 10 MeV for MSTW2008 NLO and 12 MeV for CTEQ6.6. The total systematic contribution arising from higher-order QCD eects in 9 MeV. The unfolded Z0 transverse momentum distribution is presented, and estimates of parameters in a phenomenological model describing low transverse momentum Z^0 events are extracted.

Density functional theory (DFT) is the work–horse of modern materials modeling techniques, but scattered evidence indicates it often fails for important surface properties. This thesis investigates how DFT estimates of the surface energy (σ) and molecular adsorption energies of ionic systems are affected by the choice of exchange–correlation (xc) functional. Accurate diffusion Monte–Carlo (DMC) and quantum chemistry (QC) calculations are presented for these quantities showing marked improvement over DFT and agreement of much better than chemical accuracy. DFT estimates of σ are presented for the (001) surfaces of LiH, LiF, NaF and MgO. Five xc functionals, LDA, PBE, RPBE, Wu–Cohen and PW91 are used. A clear xc functional bias is demonstrated with σLDA > σWC > σPBE > σPW91 > σRPBE. To improve the picture detailed pseudopotential DMC calculations are presented for LiH and LiF. The lattice parameters and cohesive energies agree with experiment to better than 0.2 % and 30 meV respectively. For LiH novel all–electron DMC calculations are also presented showing significant improvement over pseudopotential DMC. Accurate all–electron Hartree–Fock calculations of σ for LiH(001) and LiF(001) are presented along with calculations of the LiF bulk using specially adapted Gaussian basis–sets. Combined with existing QC correlation estimates the bulk and surface properties of LiH and LiF show excellent agreement to both experiment and DMC and allow a longstanding disagreement between two experimental estimates for σLiF to be resolved. Finally the adsorption energy curve for water on LiH(001) is obtained by both DMC and incremental QC techniques leading to agreement of better than 10 meV. DFT and dispersion corrected DFT estimates are also presented highlighting the large xc functional dependence. Thus we demonstrate that is possible and necessary to obtain agreement between higher levels of theory and produce benchmark values beyond DFT.

Multiferroic materials (in which electric and magnetic order coexist) that also display magneto-electric coupling have recently raised considerable interest as candidate compounds for advanced applications in electronics and data storage. In particular, the magneto-electric coupling is relevant in those materials such as TbMnO3 and Ni3V2O8 in which the onset of a cycloidal magnetic order drives the formation of a ferroelectric state. A key feature in these compounds is the possibility to control the population of magnetic domains (defined by the handedness of the cycloids) by an in situ electric field. The combination of magnetic non-resonant diffraction by circularly polarised X-rays with the full linear polarimetry of the scattered beam opens the way to a new class of experiments, in which the magnetic order of complex magnetic materials under applied electric and magnetic fields is probed. This technique brings a strong experimental sensitivity to the imbalance in the domain populations, since the handedness of the circular polarisation naturally couples to the sense of rotation of the magnetic moments, leading to an accurate description of the domain state and to the refinement of the magnetic structure. The results shed more light on the complex magnetic structure of TbMnO3, a challenging test case due to its two magnetic sublattices on the Mn and Tb sites, by identifying components of the ordering on the Tb sublattice and phase shifts that earlier neutron diffraction experiments could not resolve. In the case of Ni3V2O8, the method not only facilitated the refinement of the magnetic structure, but also allowed real space images of the magnetic cycloidal domains to be obtained. Their evolution is followed as they are controlled via magneto-electric coupling by the applied electric field and cycled through a hysteresis loop, thus collecting valuable information on domain formation, inhomogeneities and domain wall movement.

Carbon, along with nitrogen and oxygen, is produced by stars of differing mass and metallicity throughout the evolutionary history of galaxies. The production of oxygen and nitrogen is believed to be dominated by stars of high and low mass respectively, while the origin of carbon is less settled, as it can be produced by both low and high mass stars. An observational approach to determining whether low or high mass stars dominate carbon production is desirable, via studies of the nebulae that such stars produce during their advanced evolutionary stages. However, ionized carbon does not have forbidden emission lines in the optical range, making optical carbon abundance measurements reliant on the use of carbon recombination lines or neutral carbon forbidden lines. Carbonaceous dust is inferred to exist in many nebulae, though the amount of carbon in such dust can be difficult to determine. This thesis presents observations and numerical modelling results aimed at tracing the origins of carbon in galaxies. The contribution of individual stars is probed, focusing first on nebulae around massive Wolf-Rayet (WR) stars, particularly those with C-rich WC stars. The properties of the population of Galactic and LMC circumstellar nebulae around WR stars are examined, followed by a spectroscopic investigation of abundances in nebulae around both WN and WC stars. Carbon production rates by low and intermediate mass stars are inferred from published carbon abundance measurements for planetary nebulae. The second approach used to trace the origin and evolution of carbon is through numerical modelling of the chemical histories of galaxies. Using various formulations for the inputs of C, N and O by low and high mass stars, models are constructed which trace the overall abundances of these elements over the history of a galaxy, from their birth to the present day. By tuning the input data for stellar elemental yields to best match observed abundance patterns, the mass and metallicity ranges which are responsible for creating carbon can potentially be diagnosed. Finally, these models are adapted to investigate the evolution of the dust content of galaxies, including galaxies at high redshifts.