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This thesis describes a study of ultra low frequency (ULF) waves in the high latitude ionosphere. These waves have been observed by means of a high frequency (HF) Doppler sounder known as the Doppler Pulsation Experiment (DOPE). The ULF waves perturb the phase path which produces a small Doppler frequency shift in the received radio signal. These Doppler signatures can be related to the ULF wave characteristics. The receiver is computer controlled and dedicated software enables the system to run unattended for several weeks. The archived data are returned to Leicester for analysis. The sounder is located in northern Norway near the EISCAT radar installation. A statistical study of an earlier data set collected at the same location has established the diurnal, seasonal, solar cycle and geomagnetic activity variations of the ULF wave signatures. The effectiveness of the technique for observing ULF waves has also been investigated and this has allowed the optimisation of DOPE for studies of ULF waves. The first results from DOPE indicate that two distinct types of waves are present; those which have a correlated ground magnetic signature and those which do not. The "correlated" events are associated with field line resonances in the Earth's magnetosphere. The "uncorrelated" signatures are divided into events which occur in the morning and afternoon sectors. The morning events are reminiscent of giant pulsations which occur under quiet geomagnetic conditions. Afternoon waves coincide with depressions of the Dst index and are consistent with observations of storm time ULF waves. The "uncorrelated" waves are not observed by ground based magnetometers because of their high azimuthal wave numbers. The Doppler technique has proved to be a powerful tool for ULF wave studies and a number of ULF wave features have been identified for the first time.

One of the larger questions within the study of X-ray Binaries currently concerns the geometry of the accretion disc during the so called ’hard state’. A model involving a truncated disc is often used to explain the properties of the hard state, but there is still disagreement on the extent to which it is necessary. Presented in this thesis are three studies related to this issue. The first looks into the changes in the accretion geometry using an argument based around radiative efficiency. Periods of exponential decay before and after the soft- to hard-state transition are found. The e-folding times of these decays are measured and it is found that this value changes from ~12 days in the soft state to ~7 days in the hard state. This factor ~2 change would be expected if there is a change from a radiatively efficient regime to a radiatively inefficient regimee. The second concerns the treatment of absorption from the Interstellar Medium in studies of X-ray Binaries. Column densities for the most abundant elements are found and compared with previous results for a number of sources. Simulated data is also used to test the impact of using incorrect column densities and older X-ray absorption models on spectral analysis. It is found that the use of incorrect absorption parameters can have a large effect on the results of spectral fitting. The third directly tests for the presence of a truncated disc by fitting a model to energy spectra from the XMM-Newton/EPIC-pn instrument. The model assumes the accretion disc extends down to rISCO at all times, and is fit to a large range of observations in both the hard and soft states. In the majority of cases there is no explicit need for a truncated disc in either the soft or hard state.

The main purpose of this work was to investigate methods of producing nanoparticles with higher magnetic moments and saturation magnetisations than in current commercially available (Fe-oxide) nanoparticles. Such nanoparticles could be used to realise novel treatment of cancer, magnetic nanoparticle hyperthermia (MNH). These particles can also be optimized for use as magnetic resonance imaging (MRI) contrast agents and in a novel imaging system called magnetic particle imaging (MPI). It is advantageous to use pure Fe as the nanoparticle material as it has a much higher magnetisation than Fe-oxide, so these nanoparticles should perform better in MNH. In medical applications however, pure Fe needs to be encapsulated in a biocompatible shell, so high-performance nanoparticles need to be produced as core-shell particles. Here, data is presented from Fe@Cu, Fe@Ag, Fe@Al, Fe@Mg core-shell nanoparticles, and a set of pure Fe nanoparticles. Transmission electron microscopy (TEM) images were utilised for obtaining detailed nanoparticle size and shape distributions, and, specifically, were also analysed using a novel parameter: the geometry factor. The geometry factor is the ratio of the true area of the nanoparticle (in 2-D), divided by its maximum possible area if it were scaled to a sphere: a less subjective manner to judge particle shape than by eye. Composition analysis was performed using energy dispersive x-rays (EDX). The magnetic nature of our nanoparticles was investigated through magnetometry. Measurement of the magnetisation (M-H curves) enabled the magnetic moments of the samples to be determined. Our best performing nanoparticles were pure Fe with a saturation magnetisation higher than that of bulk pure Fe (0.220 Am2/g) of 0.262 ± 0.026 Am2/g at 300 K. These nanoparticles were produced at room temperature (21 ± 2 oC), a mean diameter of ~18 nm, and a geometry factor of ~0.8, indicating they are likely to contain mostly cuboctahedral shapes.

Thesis aims to perform appropriate preparatory work for the Raman Laser Spectrometer (RLS) on ExoMars. In order to test the prototype instrumentation it is important to select analogue samples as close as possible to the drill core that ExoMars will analyse. Work with 200 thousand spectra from the first 1000 sols of ChemCam operation on the Mars Science laboratory detected the presence of a basalt – trachybasalt igneous compositional trend, rich in alkali feldspar. These studies informed analogue sample selection at a Martian analogue site in the Utah desert as part of the MURFI rover trials. A flight representative Raman spectrometer was used in the field to acquire spectra. These were used to select a collection of analogues for further studies with RLS prototype instruments. These samples were chosen to be representative of the diverse mineralogy of the analogue site, this included; quartz, gypsum, anhydrite, celestine, barite and calcite. Work to fully characterise these samples used grain scale 532nm and 785nm Raman microscopes and an X-ray diffractometer instrument in order to determine the full composition for comparison with the capabilities or RLS. Nine of these samples were then analysed with the RLS Engineering Qualification Model to give as representative a view of RLS mission operation as possible. These studies found that whilst the RLS data was lower in spectral resolution and SNR compared to the laboratory instrumentation, it still possessed clear Raman bands enabling identification of all but two samples. These two samples were further analysed with the UK RLS prototype where additional Raman observation points produced clear bands allowing for the identification of the remaining samples. Recommendations for RLS operation and further testing include increasing the number of observation points on each sample and further testing with phyllosilicate analogues of the possible ExoMars landing site Marwth Vallis and Oxia Planum.

A study was made of the lichen vegetation of south-west Hampshire and, in particular, in the vicinity of the oil refinery at Fawley. The macrolichen vegetation of oak boles shewed a consistent pattern of deterioration in terms of the frequency and cover of individual species in relation to the urban areas of Poole-Bournemouth and Southampton and the oil refinery at Fawley. Differential species sensitivity/tolerance to air pollution was found. Sulphur dioxide is considered to be the primary causal factor of this deterioration, with other environmental factors modifying the response. In particular, varying land-use appears to account for irregularities in the pattern of deterioration. Acidification of the substrate upon which lichens grew was found in polluted areas and its influence is considered to be contributory to the direct influence of sulphur dioxide on lichen propagules and thalli. The use of lichens to estimate sulphur dioxide pollution is discussed. Their use to distinguish between relatively unpolluted ('clean'), becoming polluted and polluted conditions, using simple quantitative measurements involving the minimum of species identification, is advocated for non-professionals for primary surveys. The lichen vegetation of the south-eastern flank of the New Forest was found to be in a state of deterioration and is seriously threatened by the continued industrialization and urbanization of the western shores of Southampton Water.

A review is made of supernovae, supernova remnants and pulsars, with particular reference to the Vela X SNR and PSR0833-45. A detailed description is made of two experiments built and flown on a Skylark sounding rocket. One of these made a one-dimensional scan of the Vela X and Puppis A SNRs in the energy range 0.2--2 KeV. The second experiment sought pulsed emission from PSR0833-45 in the energy range 1.3--13 KeV. The results of the above experiment are presented, including one-dimensional profiles and upper limits to pulsed emission. Finally, data is presented from the observations of the general Vela region by the Sky Survey Instrument on board the Ariel V satellite. In particular, a synchrotron x-ray emitting region about 2 in diameter is indicated, centered upon the Vela Pulsar.

This thesis describes the design, calibration and analysis of data from two experiments flown on Skylark sounding rockets to observe X-rays from celestial sources. The first experiment, SL 904, was flown in November 1970 from woomera, and carried a large-area X-ray proportional detector, sensitive over 1-14 Kev. The objectives were to observe the X-ray background radiation as well as the source M87 and sources in Centaurus. Measurement of the degree of uniformity of the X-ray background is a valuable clue to its origin since if this is in discrete sources then, on a sufficiently small scale, spatial variations in the flux will be observable. Three scans were made with the instrument over an area lacking known sources, resulting in a lower limit of 7 x 104 for the number of sources which could produce the observed uniformity. The background spectrum over the range 1-10 KeV mas measured with a precision equal to previous results and mas in agreement. The second experiment, SL 1002, was carried out in September 1971, to obtain the position of the X-ray source GX 3+1 accurately, in one dimension, by observing the occultation of the source by the moon. The observation resulted in the source error box being reduced to 1.6 arc sec by 3 arc min (1). However, no optical object was identifiable with the X-ray source, although the error box of a possible radio source overlapped. In conjunction with higher energy measurements, the source is shown to be of thermal origin. No temporal fluctuations mere observed. Work on a focussing X-ray collector to observe low energy (0.1 - 1 KeV) X-radiation from sources is described. The characteristics of the mirror system are investigated and the calibration of the multi-mire detector is also described.

Experimental and theoretical approaches to the quantification of electron lateral and longitudinal diffusion coefficients and drift velocity in gases are reviewed. The development and arrangement of the experiments to measure transport coefficients are discussed. The procedures used for measuring these in counter gases at low electric field strength to pressure ratios are given. Lateral diffusion coefficient to mobility ratios were determined for electrons in the following gases; 100% methane, argon + methane mixtures (in the proportions 25% / 75%, 50% / 50% and 90% / 10%), 100% carbon dioxide, argon + carbon dioxide mixtures (in the proportions 50% / 50%, 75% / 25% and 90% / 10%), argon + 5% carbon dioxide + 3% acetylene, argon + 25% isobutane and neon + 10% methane. Drift velocities and longitudinal diffusion coefficient to mobility ratios were determined in 100% methane, argon + 50% methane and argon + 10% methane. The experimental results for the lateral diffusion coefficient to mobility ratio and the drift velocity are presented as functions of the ratio of the electric field strength to gas pressure and are compared with predictions made by solution of the Boltzmann equation and by Monte-Carlo simulation. Less reliable are the results for the longitudinal diffusion coefficient to mobility ratio, these are given as functions of the electric field strength to pressure ratio and compared with predictions made by Monte-Carlo simulation. The inadequacy of the arrangement to measure longitudinal diffusion is considered together with its value for the determination of the other coefficients.

The analysis of observations of 50 radio-loud and radio-quiet quasars made by the X-ray satellite Ginga is presented. The spectra, the most accurate and sensitive yet in the 2-20 keV band, provide a unique opportunity to study the hard X-ray emission from these faint, though highly luminous objects. The properties of the X-ray continuum are compatible with previous studies, and reveal a significant measured spread on the spectral index, which is unlikely to be due to spectral variability or to the radio heterogenity of the sample, indicating a true variety of spectral index amongst objects. The flux variability shown by the radio-loud objects is greater than that shown by the radio-quiet objects, but there is no indication of any differences in spectral variability, which is generally low. There is a strong relationship present between the X-ray spectral index and radio loudness, with radio-quiet quasars on average having softer spectra. The spectral index of the radio- loud objects appears to depend on orientation, with objects having the jet closer to sky plane showing steeper spectra than those pointed more towards the Earth. A number of the spectra show features, with non-Galactic absorbtion and Fe Ka line emission being detected. Spectral flattening above 10 keV reported for Seyfert galaxies and attributed to Compton 'reflection' is not strongly supported. The observed difference in the spectral distributions of the radio-quiet quasars and Seyfert galaxies can be accounted for by the absence of warm absorbing material in some objects. The results presented are consistent with current unified models, and with the idea of relativistically beamed X-ray emission in the radio-loud objects. It is likely that more than one mechanism contributes to the beamed emission, with the spectra of these objects depending on orientation, and on the relative luminosities of the non-thermal and thermal continua.