Upper Tropospheric Humidity (UTH) has a strong control on clear-sky Outgoing Longwave Radiation (OLR). Moisture from the boundary layer is transported to the drier upper troposphere by convective ascent in the tropics and realised in the form of deep convective clouds. The spatial and temporal response of UTH and the corresponding OLR are cause for debate. This study uses geostationary satellite imagery from the Spinning Enhanced Visible and InfraRed Imager (SEVIRI) to estimate UTH using water vapour channel radiances. Deep convection over Tropical Africa is detected using the difference between 6.2 mm and 7.3 mm brightness temperatures. The sensitivity of TOA brightness temperatures to cloud properties including cloud top height and optical depth are modelled using the Santa Barbara Disort Atmospheric Radiative Transfer model with thresholds developed using colocated matchups with CloudSat and CALIPSO cloud classifications. The most appropriate thresholds are determined using probability statistics and receiver operating characteristic curves. Deep convective clouds are tracked over their lifetime in June and December 2010 using a cloud tracking algorithm, based on an area overlap method. A general robust pattern in the UTH response emerges. A stronger response of UTH is found in the spatial domain than that over the temporal domain. UTH decreases with distance from the cloud edge, whilst a small increase is seen over the cloud lifetime. This was found to be controlled by cloud size and cloud lifetime, with larger and longer lived clouds causing a stronger perturbation in UTH. The UTH response was found to be stronger in June than in December. A strong negative correlation is found between UTH and OLR perturbations, with OLR measured using the Geostationary Earth Radiation Budget (GERB) instrument. This pattern is stronger in December than June.

Periodically driven quantum systems offer an exceptional platform for quantum simulations due to the possibility to approximate their dynamics in terms of time-independent effective Hamiltonians. This, together with the recent experimental advances, has situated driven systems at center stage of engineered quantum-mechanical devices. The aim of this thesis is to develop theoretical methods in order to design optimal quantum simulations with driven systems. By applying the derived tools to experimentally relevant models, the applicability and significance of the methods are furthermore demonstrated. First, we introduce a method to derive accurate effective Hamiltonians by merging two seemingly unrelated tools: Floquet theory and flow equations. With this, the required analytical identification of the effective Hamiltonian in terms of the system's parameters is achieved. Second, we identify structural properties that determine the accessible effective dynamics of a system of particles on shaken optical lattices, which is arguably one of the most remarkable systems for many-body quantum simulations. In particular, we identify fundamental symmetries of the underlying lattice geometry that determine the emergence of new tunneling processes. Third, we develop an optimal control scheme to design polychromatic driving protocols that optimally simulate specifically targeted dynamics. We apply this scheme to demonstrate an optimal realization of Raman transitions with a Lambda system, a building block in many quantum simulations. Then, we employ it to implement a topological Chern insulator through suitably engineering the geometry-dependent tunneling of particles on a shaken hexagonal lattice. Hereby, a realistic route to experimentally test strongly-correlated topological phases of matter is provided. By determining structural properties of driven systems and suitable driving protocols, the methods described in this thesis open substantial possibilities for the development of optimal quantum simulations and, ultimately, reliable quantum technologies.

Ocean circulation and storm surge models have neglected mass contributions from precipitation and can have a systematic bias in sea surface height (SSH). Here, a new rainfall scheme has been set up in the ocean circulation model Regional Ocean Modelling System (ROMS) to incorporate the effects of precipitation mass. When precipitation is added to the sea surface, it spreads out via surface gravity waves that increase in propagation speed with increasing water depth. Over several days, the increase in SSH due to the precipitation mass added created a geostrophic adjustment, generating clockwise-rotating geostrophic currents around the SSH increase. The transfer of momentum from precipitation to the sea surface, or rain stress, is investigated in ROMS. An error in the existing implementation of rain stress has been uncovered and corrected. The existing ROMS code generated an error in the direction of rain stress by up to 45° and systematically overestimated its magnitude by 41%. The SSH response to wind stress is examined. Positive and negative surges are generally generated by onshore and offshore winds respectively. While positive surges are widely studied, negative surges are less well understood. Negative surges are larger in magnitude and extend further across the coastline than positive surges. It is shown for the first time that the alongshore component of the wind stress is the main contributor to the asymmetrical surge response. Without this component, the ratio of negative to positive surge can decrease by more than half. This asymmetry also increases with increasing latitude and decreasing depth. In the case study of a real tropical cyclone, Monica, the effect of incorporating precipitation mass is compared with other processes affecting storm surge: surface wind, inverse barometer effect and rain stress. The maximum SSH response is 170.6 cm for the wind effect, 61.5 cm for the inverse barometer effect, 7.5 cm for the effect of rain stress and 6.4 cm for the effect of rain mass. Each process has been shown to have different spatial influences. The effect of rain mass has a strong remote influence compared to the inverse barometer effect and the effect of rain stress. This is particularly seen in semi-enclosed bays.

In this thesis, I will discuss two separate topics which are related to gravitational wave production in the early universe. The first part will focus on the tensor power spectrum from inflation, derived using the Ashtekar variables of loop quantum gravity. This formalism is different from the ordinary approach in that it uses a complex connection as the central gravitational variable instead of the metric. Although the choice of variables should not affect any classical results, it becomes vital when considering quantum mechanical quantities like vacuum fluctuations. We will find that in this formalism, the tensor power spectrum is chiral, which would lead to a non-zero TB correlator in the CMB. Obtaining the full TB power spectrum would enable us to probe this chirality and provide clues about the nature of gravity. In the second part, I will consider gravitational waves produced from massless preheating, during which the inflaton transfers energy to a scalar field chi. If chi is light, it acquires a scale invariant spectrum of perturbations from inflation. At the time of preheating, the field will therefore have fluctuations on superhorizon scales and take a different value in different parts of the observable universe. I will study GW production for different initial values of chi numerically using 3d lattice simulations. The GW amplitude strongly depends on this initial value, leading to a GW background that is anisotropic today, with relative fluctuations of order 1%. In general, anisotropies will occur in any model of preheating with a light scalar field, and the characteristics should strongly depend on the model parameters. If a GW background from preheating was measured in the future, it would provide a novel way to distinguish between different inflationary scenarios.

In this thesis, we investigate non-perturbative features of strongly coupled condensed matter systems, generically, placed at finite temperature, charge density and, possibly, in a magnetic field using the theoretical framework of the gauge/gravity correspondence. According to the dictionary of the duality, such field theories are related to charged black holes in one dimension higher that emerge from weakly interacting gravity theories. Following this approach, progress has been made in understanding some of the universal features of field theories at strong coupling, with new classes of black holes being discovered along the way. The bulk of the thesis consists of four interconnected parts. In the first, we study magnetically charged black holes and we find that, at some critical temperature, a new branch of spatially modulated branes appears, corresponding to a dual field theory with a current density wave. In the second part, we investigate the ground state of strongly coupled field theories placed in magnetic field, within the context of gauged supergravity in D=4,5 dimensions. This analysis revealed a rich structure of instabilities and, in particular, showed that only the supersymmetric solutions correspond to stable configurations. In the third part, we consider a generalised version of local quantum critical points, called η-geometries, in the context of U(1)^4 supergravity in D=4 dimensions. We show that the latter theory admits extremal black holes carrying three non-zero electric or magnetic charges which approach an η=1 geometry in the IR, while a small fourth charge resolves the singularity of the η-geometry replacing it with an AdS_2XR^2 factor in the far IR. Finally, in the last part, we discuss the possibility of spatially modulated superconductors. We construct electrically charged black holes dual to four dimensional CFTs in a superfluid phase with either p-wave or (p+ip)-wave order and we discuss their thermodynamic properties, the corresponding ground states as well as the competition of the two types of order.

Results are presented of a search for the Standard Model (SM) Higgs boson decaying into two photons at the Compact Muon Solenoid (CMS) experiment housed at the Large Hadron Collider (LHC), CERN. An excess of events is observed over the background expectation with a local significance of 5.7 (lower-case sigma), where the SM expectation is 5.2 (lower-case sigma), constituting a standalone discovery of the particle first observed by the ATLAS and CMS experiments in July 2012. Measurements of the particle's signal strength, mass and couplings are presented along with an analysis of its spin. The results show a high level of compatibility with the predictions for a SM Higgs boson. The observed state's signal strength relative to the SM expectation is found to be lower-case sigma/lower-case sigma_{\mathrm{SM}}=1.14^{+0.26}_{-0.23}$. The observed state's mass is found to be $124.72\pm 0.35$~GeV. The signal strength relative to the SM expectation when probing production mechanisms through fermionic modes only is 1.13^{+0.37}_{-0.31}, and from bosonic production modes only is 1.16^{+0.63}_{-0.57}. A spin-2 graviton, produced entirely by gluon fusion, is excluded at 94\%~C.L.~(92\% expected) and a spin-2 graviton, produced entirely by quark-antiquark annihilation, is excluded at 85\%~C.L.~(83\% expected).

Nanoplasmonic surfaces are known to be able to alter the localisation and propagation characteristics of light owing to the subwavelength interactions with the metallic elements. The recent improvements of nanolithography and self-assembly techniques have enabled the design of ever smaller and intricate structures with a high precision, allowing for research into more complex nanoplasmonic structures that control light on the nano-scale. Up until now, plasmonic surfaces are mostly operated with out-of-plane excitation which, although well-established and experimentally convenient to perform, has limited potential for on-chip applications. The integration of surface plasmonic structures with photonic waveguides allows for light to be confined to a guiding layer while being kept in interaction along the surface structure without inducing uncontrolled scattering or excessive dissipative loss. In this work, plasmonic surface structures such as plasmonic antennas and array structures that are integrated with a CMOS compatible platform are explored. In particular, a new class of plasmonic surfaces, plasmonic nanogap tilings, are introduced. Remarkably, these simple periodic structures provide a rich physics characterised by many different regimes of operation, including subwavelength surface enhancement, hybrid plasmonic-photonic resonances, transmission stop-bands, resonant back scattering, coupling to out-of-plane radiation and asymmetric transmission. The ability of the nanogap tiling to concentrate the field on the surface is studied in detail as it allows for sensing changes in the dielectric medium on the accessible surface or the inclusion of nonlinear or gain materials to functionalise the device in an integrated setup.

The Standard Model does not describe several phenomena, such as gravity and dark matter, and therefore is an incomplete description of nature. This demands the existence of new physics beyond the Standard Model. Two searches for new physics are presented in this thesis, along with a sensitivity study for a third analysis sensitive to new physics. The vMSM model motivates a search for lepton number violation using B+ -> h- μ+ μ+ decays, where h = (pi, K). No B+ → h- μ+ μ+ candidates are seen in ~ 36 pb -1 of LHCb data and limits are set of BR (B+ → K- μ+ μ+) < 4.1 x 10 -8 and BR (B+ → pi- μ+ μ+) < 4.4 x 10 -8 at 90\% C.L. These improve the previous best limits by a factor 40 and 30, respectively. Using ~ 1fb -1 of LHCb data, the B+ → pi+ μ+ μ- decay is observed for the first time with 5.2 sigma significance. This is the first b → dμ+μ- transition to be observed. The B+→ pi+ μ+ μ- branching fraction is measured to be (2.3 ± 0.6 (stat) ± 0.1 (syst)) x 10 -8. The ratio of branching fractions between B+ → pi+ μ+ μ- and B+ → K- μ+ μ- is measured to be 0.053 ± 0.014 (stat) ± 0.001 (syst), and this is used to determine a value of the ratio of quark mixing matrix elements Vtd| /Vtd| = 0.266 ± 0.035 (stat) ± 0.003 (syst). All of these results are compatible with the Standard Model expectations. Previous measurements of the ratio of B → D(*)τ+v and B → D(*)μ+v branching fractions exceed the Standard Model expectations by more than 3 sigma, combining D and D*. These decays are challenging to measure at a hadron collider, due to the presence of neutrinos in the final state. A sensitivity study is presented for a measurement of the ratio of B0 → D*τ+v and B0 → D*-μ+v branching fractions at LHCb. This study includes a novel fit method, and two new algorithms which enable the backgrounds to be controlled, and control samples to be isolated. The estimated uncertainty on Rd*, including the largest systematic uncertainties, is ~ 8\%, competitive with the 9\% uncertainty on the present best measurement of Rd*.

The presence of hydrogen (H) is deleterious to many metals and alloys, and results in the loss of integrity by a number of embrittlement processes. The zirconium (Zr) alloys used throughout the nuclear industry to produce protective fuel cladding are highly susceptible to one form of H embrittlement: Delayed Hydride Cracking (DHC), which occurs because Zr is a hydride-forming metal. H atoms are introduced into the fuel clad by the corrosion reaction and diffuse along stress, temperature and concentration gradients. DHC occurs when H diffuses along the stress gradient caused by a crack in the clad. Once enough H accumulates and the precipitation solvus is reached, brittle hydrides grow ahead of the crack and eventually enable the crack to propagate. The process then begins again with H diffusion. The present work is aimed at modelling H diffusion in Zr under the influence of the elastic field caused by dislocations, as a precursor to the diffusion of H to cracks. A combination of first principles Density Functional Theory (DFT) simulations, atomistic simulations with Embedded Atom Method (EAM) Empirical Potentials (EPs), and analytical models are used to simulate H diffusion to a dislocation on the continuum scale, incorporating the elastic interaction energy between H and the dislocation as a driver. The defect forces exerted by interstitial H on neighbouring Zr atoms are calculated using DFT and EP methods. The free energy of H in Zr as a function of applied strain is also calculated using both DFT and EP. These quantities are then used to evaluate the elastic dipole tensor of H in Zr using two approaches: the defect forces method, and the strain method. Expressions for the dipole tensor are derived using the two approaches and their methods of calculation are also described. The purpose of evaluating the elastic dipole tensor is to illustrate the anisotropy of the elastic field of H in Zr. It is shown that the elastic field of H can be more accurately described as a misfitting prolate spheroid, than by the typical misfitting sphere approach. The calculated dipole tensors using both methods and both simulation techniques show that the dipole tensor components ρ11 = ρ22 ≠ 33, which is representative of the fact that the hexagonal close-packed (HCP) crystal is isotropic in the basal plane and has a non-ideal c/a ratio. It is shown that the defect forces method yields a conditionally convergent sum, requiring the forces to fall as 1=|R3| or faster to obtain a converged dipole tensor, where R is the radial distance between H and surrounding Zr atoms. This is not satisfied when using DFT, whereas converged forces are obtained using the EP. It is found that there is no numerical agreement between the strain and defect forces method dipole tensors using either DFT or EP, and that this mismatch can be attributed to the series of assumptions that lead to each expression for the elastic dipole tensor. Using DFT, the ρ11 component of the dipole tensor is found to be lower than the ρ33 component (ρ11 = 1.68 eV and ρ33 = 1.74 eV for a 96-atom supercell), whereas the EP technique yielded a higher ρ11 component (ρ11 = 3.94 eV and ρ33 = 3.68 eV for a 96-atom supercell). The reason for this is attributed to an underestimation of the strength of the Zr-H bond by the EAM potential developed by [1]. The work-done formulation for the elastic interaction energy is used to compute the elastic interaction energy between H interstitials and dislocations in Zr, without needing to simulate H and a dislocation together in a single simulation cell, which can become computationally expensive, particularly for edge dislocations. This new approach also combines atomistic simulations with continuum models, and can be scaled up to evaluate the interaction between H interstitials and cracks, or any other displacement field, whilst also accounting for anisotropy. The computed elastic interaction energy is used in a stress driven diffusion calculation to model the diffusion of H to dislocations. Two dislocation elastic fields are compared: a prism dislocation with dislocation line oriented along the c-axis and b= (a/3) [2⁻1 ⁻10], and a basal dislocation with dislocation line oriented in the basal plane and b= (a/3) [2⁻1 ⁻10]. It is shown that since the elastic field of the prism dislocation is isotropic, the elastic interaction between H and the dislocation will also be isotropic. Therefore a dislocation oriented in another direction, with a non-zero displacement field component along the crystal c-axis, is required to highlight the anisotropy of its elastic interaction with H. This is shown to be the case with the basal edge dislocation. It is shown that both the prism and basal dislocations become saturated with H within 2 picoseconds at 300K, with H accumulating around the basal dislocation more rapidly at all temperatures. Furthermore it is shown that at low temperatures, the basal dislocation in particular can act as a nucleation site for hydrides, by attracting enough H to its atmosphere to exceed the solubility limit. The work presented in this thesis is a theoretical characterisation of the elastic field of H in Zr, its elastic interaction with dislocations, and its diffusion to dislocations, whilst accounting for anisotropy. The above is work that has not yet been performed on the Zr-H system.

The breakthrough discovery of a nanoscale optically gated ion channel protein, Channelrhodopsin 2 (ChR2), in combination with a genetically expressed optically activated ion pump, Halorhodopsin, allowed the direct stimulation and inhibition of individual action potentials with light alone. This thesis describes the development of optics and micro-optics which when used with micro-led array sources, collects and projects light efficiently and uniformly onto such opto-genetically modified specimens. When used with enhanced light gated ion channels and pumps these systems allow us to further our understanding of both brain and visual systems. Micro-LED arrays permit spatio-temporal control of neuron stimulation on sub-millisecond timescales. However, micro-led arrays are disadvantaged by the broad-angular spread of their light emission and their low spatial fill factor. We present the design of macro and micro-optics systems for use with a micro-LED arrays consisting of a matrix of 25μm diameter micro-LEDs with 150 or 80μm centre-to-centre spacing. On one system, the micro-LED array is imaged onto off-the-shelf micro-optics using macro-optics and in the other system; micro-LED array and custom micro-optics are optimised and integrated together. The two systems are designed to improve the fill-factor from 2% to more than 78% by capturing a larger fraction of the LED emission and directing it correctly to the sample plane. This approach allows low fill factor arrays to be used effectively, which in turn has benefits in terms of thermal management and electrical drive from CMOS backplane electronics. These systems were implemented as an independent set that could be connected to a variety of different microscopes available for Patch-clamp and Multi-electrode measurements. As well, the feasibility of an eye prosthesis was tested using virtual reality optics and a fake eye to stimulate ganglion cells and by doing in-vivo stimulation of the genetically modified retina of a mouse.