Recently, an increasing number of modelling and observational studies have looked at the signatures of small-scale waves, such as gravity waves (GWs) of meteorological origin, in the upper atmosphere. General circulation models require an appropriate GW parameterisation to reproduce a realistic global circulation. Existing schemes implemented into GCMs lack a physically proper wave dissipation mechanism above the turbopause. For more self-consistent wave propagation in GCMs, and to estimate their dynamic and energetic importance in the upper atmosphere, it is crucial to account for realistic upper atmospheric dissipation processes. The UCL Coupled Middle Atmosphere-Thermosphere-2 (CMAT2) general circulation model was developed in order to investigate atmospheric vertical coupling. This model is an updated version of its predecessor CMAT. Three GW parameterisations of different characteristics have been implemented into CMAT2. While they all, to some extent, reproduce the necessary mesosphere and lower thermosphere (MLT) dynamics, artificial dissipation above the turbopause is a problem in all these schemes. Therefore, an extended spectral non-linear GW parameterisation, which incorporates more physically realistic GW dissipation, has been developed. Using an offline column model, the sensitivity of GW propagation and dissipation in the thermosphere-ionosphere has been studied. Considerable GW propagation into the upper atmosphere is demonstrated. The associated wave forcing and heating are significant. This new extended scheme has been implemented in CMAT2. Its dynamical effects on the circulation of the upper atmosphere have been investigated. Results demonstrate the importance of GW momentum flux divergence in the thermosphere-ionosphere. The extended scheme improves the model simulations markedly with respect to an empirical model.

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This thesis is composed of two parts: gravity in the spacetime with a negative/positive cosmological constant. The first part, which is the negative case, devotes to constructing the IIB supergravity dual solution in AdS/CFT correspondence for N = (1, 0) and N = (1/2, 0) non-anticommutative deformed super Yang-Mills theory. The non-anticommutativity is realised on N D3-branes in certain constant self-dual RR 5-form background fields. These background fields can be sourced by a set of additional D3-branes intersecting the N D3's. By taking the near horizon limit to the brane configurations, the supergravity solutions are obtained. The mapping between the bulk scalar fields and the boundary operators for N = (1, 0) case is investigated, and it is found that the spectrum of a particular class of the BPS operators is not deformed by the non-anticommutativity. The second part is for the positive cosmological constant case. In this part, a black fusiform solution with appositive cosmological const in d =5, N = 4 de Sitter supergravity is constructed. The solution is obtained via the braneworld Kaluza-Klein reduction ansatz, and preserves half of the de Sitter supersymmetry. It is static, with the gravitational contraction being balanced by the cosmological repulsion. The black fusiform has an event horizon and a cosmological horizon, and is asymptotically non-de Sitter. The horizons are of an in x S(^2) topology, and contain singularities at the opposite ends due to the nature of the reduction ansatz. Despite the singularities, the solution exhibits some physically properties compatible with that of the regular asymptotically de Sitter spacetimes. The entropy and mass observe the N-bound proposal and the maximal mass conjecture respectively. It also carries a charge which contributes to the 1st law of black hole mechanics.

Neutron-deficient nuclei along the proton drip line in the mass region 80-90 have been populated in relativistic projectile fragmentation reactions at GSI, Germany. A 750 MeV per nucleon beam of 107 47Ag60 provided by the SIS-18 synchrotron was fragmented on a 4 g/cm2 target of beryllium. The reaction products were separated and unambiguously identified using the Fragment Separator (FRS) with its ancillary detectors. The ions produced were slowed down by means of a variable thickness aluminium degrader and implanted in a 7 mm multilayer perspex block located at the centre of the high-efficiency Stopped RISING array. Gamma rays emitted from the decay of nano-to-millisecond isomeric states were detected in the array and correlated with the arrival of the associated ion. This allowed the observation of previously unreported excited states in the odd-odd N = Z nuclei, 82 41Nb41 86 43TC43. The new data suggest the low-lying structures of these proton drip line nuclei are dominated by a T = 1, np pairing condensate. Experimental results are compared to theoretical interpretations from TRS calculations and the Projected Shell Model. The isomeric state in 82Nb is interpreted as an isospin-changing K isomer with a reduced hindrance of fv ? 18. This is the first case of such an isomeric state along the N = Z line and indeed in this mass region. Previously unreported isomeric states have been identified in 87,88Tc and 84Nb. Isomeric ratios which provide insight into the reaction mechanism and nuclear structure are calculated for all the isomers observed, including the previously identified isomeric states in 94,96Pd, 93Ru and 84Nb.

Einstein's General Theory of Relativity (1916) predicted the existence of gravitational waves. These waves can be considered as fluctuations, or ripples, in the curvature of space-time. Until now there has been only indirect evidence, produced by Hulse and Taylor, of their existence. However, for many years various groups of scientists around the world have been developing ultra-sensitive instruments and techniques which are expected to be capable of detecting gravitational wave signals. The direct detection of these waves will provide new information about the astrophysical processes and sources which produce them. Gravitational radiation is quadropole in nature, producing orthogonal stretching and squeezing of space. The resulting fluctuations in distance are, however, very small, with gravitational waves emmitted from violent astrophysical phenomena expected to produce strains in space of the order ~10 [superscript -22] over relevant timescales. One technique for detecting such strains is based on a Michelson Interferometer. The Institute for Gravitational Research at the University of Glasgow under the leadership of Professor James Hough, has been an active contributor of research targeted towards the detection of gravitational waves for over 35 years. A strong collaboration exists with the Albert-Einstein-Institut in Hanover and Golm, the University of Hanover and the University of Cardiff. This collaboration has developed and constructed a laser interferometer, with arms of 600 m length, in Germany named GEO600. The research presented in this thesis details experiments undertaken on materials and techniques used in current interferometric detectors and for proposed future detectors. The aim of this research is to investigate methods of reducing the levels of mechanical loss associated with the detector optics and thereby minimise the impact of thermal noise on the overall sensitivity of detectors.

Gravitational waves were first predicted by Albert Einstein's Theory of general relativity, published in 1916. These waves are perturbations in the curvature of space-time. Indirect evidence of their existence has been obtained via observations of binary pulsar system inspirals by Hulse and Taylor. Research is now focussed on achieving direct detection of gravitational waves, giving a new way of observing astronoomical events in the universe. Gravitational waves are quadrupole in nature, causing tidal strains in space. The weak nature of gravity means that the magnitude of these strains is very small. Only astronomical scale sources are likely to produce waves of sufficient amplitude to be detected on Earth. In the frequency band of a few Hz to a few kHz, the expected strain amplitude for violent sources is of the order of 10[superscript -22]. Detection is most likely to be achieved using long baseline interferometer detectors. Currently several such detectors are in operation worldwide, including the GEO600 detector, built in a collaboration involving the Institute for Gravitational Research at the University of Glasgow, the Albert Einstein Institute (Hannover and Golm), and the University of Cardiff. In America the LIGO detector network has three large interferometric detectors - two of 4 km arm length and one with 2 km arms. In Italy a European collaboration has constructed the 3 km VIRGO detector. Currently GEO600 and LIGO have undertaken 5 data taking science runs with the most recent year long run, also involving VIRGO, concluding in November 2007. No detections have yet been confirmed, but analysis on the results of the most recent GEO600/LIGO/VIRGO run is ongoing. These detectors are now operating at, or close to their design sensitivities, so research is focussed on reduction of various noise sources by upgrading of the detectors. One important noise source is thermal noise (both Brownian and thermo-elastic) - a limiting factor at midband frequencies. Reduction of mechanical loss in mirrors and their suspensions will help lessen the impact of thermal noise in future detectors. The research detailed in this thesis was aimed at reducing thermal noise. In particular, it covers work undertaken to investigate the mechanical loss of suspension ribbons and fibres, test mass mirror coatings and also diffractive surfaces on test masses to evaluate their suitability for employment in future advanced gravitational wave detectors. Upgrade of LIGO to "Advanced LIGO" will aim to reduce thermal noise by implementing mirror suspension techniques pioneered in GEO600. Specifically, it was initially proposed that test masses be suspended from silica ribbon fibres, a key choice that will be re-evaluated in this thesis. Ribbons (or fibres) will be fabricated by a CO[subscript 2] laser pulling machine being developed in Glasgow, with control programming being undertaken by the author. Characterising the dimensions, strength and vertical bounce frequencies of the ribbons is important to confirm their suitability for use in detector mirror suspensions. A dimensional characterisation machine was constructed to measure the ribbon's cross sectional dimensions, with emphasis being placed on achieving high resolution in the ribbon neck regions, where the most bending occurs. Also, a bounce testing machine was constructed to experimentally measure the ribbon's vertical bounce frequency. Finally a proof load test was constructed to verify that ribbons could support the required weight. Results showed that ribbons could be fabricated successfully with the required strength and bounce frequency, though shaping of the cross section still requires further research to achieve the optimum. In a pendulum system most of the energy is stored as gravitational potential energy rather than bending energy of the suspension fibres or ribbons. Thus the effective loss of the suspension fibres/ribbons is reduced or "diluted" and thermal noise is lower than may be naively expected. Dilution of the mechanical loss of the pendulum suspensions was investigated using finite element modelling. Methods for importing data from the dimensional characterisation machine were developed, and it was observed that the dilution resulting from ribbon suspensions was not as high as had been initially expected, with bending in the neck region of the ribbon being seen to significantly reduce dilution. It was observed that the rectangular ribbons had inferior dilution to equivalent cross section circular fibres for necks of the length typically being produced. A typical 7.5 mm necked ribbon was seen to have a dilution 1.5 times lower than an equivalent fibre, despite the ribbons having 3.3 times greater dilution with no necks. Ribbons were only seen to have this superior dilution for very short necks. Bending in the necks resulted in an increased amount of bending strain energy occurring which caused the lower dilution factors. Additionally, bending occurring in the ears that join the fibres or ribbons to the masses was seen to further reduce the dilution. In the light of low dilution factors, reduction (ideally nulling) of thermoelastic noise was studied. Reduction in thermal noise in this way is proposed through the use of tapered fibres, which showed that a lower overall noise level than that from the baseline ribbons planned for Advanced LIGO can be achieved, despite lower dilution factors. In the light of this work tapered fibres have now been adopted as the baseling for Advanced LIGO. Measurement of test mass mirror samples showed that the mechanical loss of mirror coatings can be significantly reduced by doping the high refractive index layer, with reduction up to a factor of 2.5 in measured mechanical loss observed, when compared to equivalent undoped coatings. In order to perform these measurements an interferometric read out system was constructed. Future detectors will use higher laser powers which may cause thermal distortions in transmissive optical components. Use of all reflective components may be required to reduce this problem, possibly via diffractive mirrors. Measurements were undertaken on samples to discover if introducing a diffraction grating to an optic's surface increased the mechanical loss. However, the grating was not seen to do this, and also did not increase the mechanical loss of an optical coating applied on top of its surface, which verified that diffractive optics are viable for use in future detectors.

A new algorithm for the analysis of gravitational wave data from rapidly rotating neutron stars has been developed. The work is based on the Markov Chain Monte Carlo algorithm and features enhancements specifically targeted to this problem. The algorithm is tested on both synthetic data and hardware injections in the LIGO Hanford interferometer during its third science run ("S3''). By utilising the features of this probabilistic algorithm a search is performed for a rotating neutron star in the remnant of SN1987A within in frequency window of 4 Hz and a spindown window of 2E-10 Hz/s. A method for setting upper limits is described and used on this data in the absence of a detection setting an upper limit on strain of 7.3E-23. A further application of MCMC methods is made in the area of data analysis for the proposed LISA mission. An algorithm is developed to simultaneously estimate the number of sources and their parameters in a noisy data stream using reversible jump MCMC. An extension is made to estimate the position in the sky of a source and this is further improved by the implementation of a fast approximate calculation of the covariance matrix to enhance acceptance rates. This new algorithm is also tested upon synthetic data and the results are presented here. Conclusions are drawn from the results of this work, and comments are made on the development of MCMC algorithms within the field of gravitational wave data analysis, with a view to their increasing usage.

Bibliography :leaves 144-[148] / xiv, [148] leaves : ill ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Dept. of Physics and Mathematical Physics, 1993