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The quadrupole moments of strongly deformed, ultrahigh-spin bands in the nucleus 154Er have been measured for the first time, providing a calibration for recent measurements made for similar bands in 157Er and 158Er using the same method. High-spin states up to ∼52ħ have been populated using the fusion-evaporation reaction 110Pd(48Ti,4nγ)154Er at a beam energy of 215 MeV, in an experiment performed at the ATLAS facility at Argonne National Laboratory, USA, using the Gammasphere detector array. Two new ultrahigh-spin bands, believed to be triaxially deformed, have been observed in 154Er in addition to the known triaxial strongly deformed (TSD) band and superdeformed (SD) axially symmetric prolate band. The quadrupole moments, Qt, of three of these bands have been measured using the Doppler-shift attenuation method (DSAM), with values of 11.0 ± 0.6 eb for the known TSD band, 19.5 ± 1.5 eb for the SD band and 10.0 ± 0.9 eb for one of the new bands. Cranked Nilsson-Strutinsky (CNS) calculations are compared with results and possible nucleon configurations are discussed. A configuration similar to that of the yrast SD band of the isotone 152Dy is assigned to the 154Er SD band. Based on their Qt, the triaxial bands appear more consistent with configurations corresponding to a TSD shape with a negative γ deformation parameter. The Qt of ∼11 eb is consistent with previous results for the four TSD bands in 157,158Er. These results challenge theoretical calculations that predict positive-γ TSD shapes to be energetically favoured over negative-γ shapes.

This thesis investigates new methods for self-organising a precisely defined pattern of intertwined number sequences which may be used in the rapid deployment of a passive indoor positioning system's infrastructure. A future hypothetical scenario is used where computing particles are suspended in paint and covered over a ceiling. A spatial pattern is then formed over the covered ceiling. Any small portion of the spatial pattern may be decoded, by a simple camera equipped device, to provide a unique location to support location-aware pervasive computing applications. Such a pattern is established from the interactions of many thousands of locally connected computing particles that are disseminated randomly and densely over a surface, such as a ceiling. Each particle has initially no knowledge of its location or network topology and shares no synchronous clock or memory with any other particle. The challenge addressed within this thesis is how such a network of computing particles that begin in such an initial state of disarray and ignorance can, without outside intervention or expensive equipment, collaborate to create a relative coordinate system. It shows how the coordinate system can be created to be coherent, even in the face of obstacles, and closely represent the actual shape of the networked surface itself. The precision errors incurred during the propagation of the coordinate system are identified and the distributed algorithms used to avoid this error are explained and demonstrated through simulation. A new perimeter detection algorithm is proposed that discovers network edges and other obstacles without the use of any existing location knowledge. A new distributed localisation algorithm is demonstrated to propagate a relative coordinate system throughout the network and remain free of the error introduced by the network perimeter that is normally seen in non-convex networks. This localisation algorithm operates without prior configuration or calibration, allowing the coordinate system to be deployed without expert manual intervention or on networks that are otherwise inaccessible. The painted ceiling's spatial pattern, when based on the proposed localisation algorithm, is discussed in the context of an indoor positioning system.

The solution photophysics of the isomeric aminobenzoic acids and N,Ndimethylaminobenzoic acids and their methyl esters were studied under a variety of conditions of solvent, pH, concentration and temperature. The most straightforward behaviour was obtained when the amino or N,N-dimethylamino substituent was in the meta- position relative to the carboxylic add or ester function. The amino compounds absorb with a peak between 300 and 325 nm depending on solvent, their fluorescence peaks lie between 350 and 410 rim. The corresponding N,N-dimethylamino compounds usually absorb and fluoresce some 20 - 30 rim to the red of these wavelengths. Both protonation and deprotonation of the ground state molecules takes place under weakly acidic conditions with pKi, values of approximately 3.0 and pK a values of approximately 5.0 being obtained. The observed variation in the fluorescence of the meta isomers with pH is largely caused by ground state equilibria. Förster cycle calculations suggest that the excited state pK a is little changed from the ground state whereas pKC is much smaller. This is in good agreement with the observed fluorescence data and the nature of the excited nglet state (usually some 10 -20 ns) than is seen for the other isomers. The fluorescence intensity of the meta- isomers was observed to rise with decreasing temperature, although this could possibly be attributed to absorbance changes. The photophysics of the corresponding ortho compounds is complicated by steric and hydrogen-bonding interactions especially in the compounds containing an N,N-dimethylamino group. The increased interaction between the two substituent groups leads to an increase in extinction coefficient and fluorescence quantum yield and a decrease in fluorescence lifetime for 2-aminobenzoic acid and its methyl ester compared to the meta derivatives. Spectral band positions, pK values and the effect of temperature on the fluorescence are similar in the two sets of compounds. The 2-N,Ndimethylamino compounds do not parallel the corresponding meta- derivatives due to steric hindrance and intra-molecular hydrogen bonding. These cause weak, blue shifted absorptions and low fluorescence quantum yields. There was no evidence found in this work for the presence of a zwitterionic species in the absorption properties of 2-N,N-dimethylaminobenzoic acid. The photophysical properties of 4-aminobenzoic acid and its methyl ester are in many ways very similar to those of the corresponding orthosubstituted compounds. However the same certainly cannot be said for 4-N,Ndimethylaminobenzoic add and its methyl ester. These two compounds exhibit anomalous fluorescence in the form of two fluorescence bands in some solvents. The appearance of this anomalous fluorescence is both concentration and solvent composition dependent. Various mechanisms to explain these observations were tested; excimer, exciplex, TICT state and ground state dimer formation. The latter was found to be in best accord with the properties of these molecules, but it was clear that in binary solvent mixtures such as hexane / acetonitrile and acetonitrile / water other mechanisms could also be involved.