Laser-induced transient absorption spectroscopy of phthalocyanine dyes

This work reports a further investigation into the spectroscopic properties of phthalocyanine dyes in solution. The technique of nanosecond kinetic spectrophotometry was applied, with excitation at both the fundamental ruby laser output wavelength (694 nm) and the second harmonic (347 nm); corresponding in energy to the first and second excited singlet states respectively of several of the phthalocyanine compounds. The resultant transient absorption spectra indicate that the same laser—induced intermediates — those that can be identified as the lowest excited states of singlet and triplet multiplicity — are produced following excitation at either wavelength. However, the transient response also displays a marked perturbation from that characteristic of a 'simple' energy redistribution process; a perturbation that is deduced to be a consequence of both the high intensity of laser excitation and the tendency of the phthalocyanine dyes to form molecular aggregates. Further evidence is proposed regarding the 'anomalous blue fluorescence' reported from this type of compound, with particular emphasis placed upon the need for a high degree of solute purity

The axial behaviour of piled foundations in liquefiable soil

Understanding the mechanisms by which any engineering structure resists load is an essential requirement for its consistent and reliable design. The axial resistance which can be mobilised by piled foundations in liquefiable soils when subjected to strong shaking remains highly uncertain, and a number of piled foundations have failed in strong earthquakes as recently as 2011 . The lack of visible foundation distress in many such cases indicates that failure can occur as a result of the loss of axial capacity during an earthquake, as opposed to the laterally-dominated failure modes which have been the focus of the research community for the last 20 to 30 years. In this thesis, a series of dynamic centrifuge experiments have been carried out to establish how the distribution of axial loads along the length of a pile changes during a strong earthquake. In each test, a 2 × 2 pile group was installed such that its tips were embedded in a dense sand layer which was overlain by liquefiable soil. The tests examine the effects arising from the hydraulic conductivity in the bearing layer, the influence of axial pile cap support and finally whether there are any differences in the behaviour of nominally jacked or bored piles under seismic loading. The pile cap has been shown to play a substantial role in supporting axial loads during strong shaking. In cases where the pile cap was unable to support axial load, the majority of the axial loading was carried as pile end bearing, with some shaft friction being mobilised in both the liquefiable and bearing soil layers as a result of relative lateral displacements between the soil and pile. However, where the pile cap is able to support axial loads, the settlement of the pile cap into the soil led to a dramatic transfer of axial load away from the piles and onto the pile cap. These results imply that where substantial excess pore pressures may be generated at the depth of the pile tip, then the pile caps must be able to support significant axial load. The increased effective stresses below the pile cap were responsible for the mobilisation of shaft friction on the section of pile within the liquefiable layer. However, these piles were unable to mobilise shaft friction in the bearing layer due to the reduced lateral loading on the piles. The axial behaviour of the piled foundations after the end of strong shaking is affected by the recovery of pile end bearing capacity and is therefore strongly dependent on the hydraulic conductivity of the bearing layer. The axial behaviour of nominally bored and jacked pile groups in liquefiable soil deposits are very different under seismic excitation, with the installation process of the latter substantially altering the soil conditions around the tips of the pile, such that in contrast to the bored pile groups, the jacked pile groups did not accumulate settlements until significantly after the strong shaking had commenced. These results imply that the method of installation is an important factor in the seismic response of a foundation, and may be more pronounced for real earthquakes where the number of strong shaking cycles may be more limited than those simulated in the experiments.This work was supported by the Engineering and Physical Sciences Research Counci

Sensitivity of SNO+ to supernova neutrinos

The Super-K experiment determined that neutrinos are massive particles by observing the oscillation of atmospheric neutrinos. The SNO experiment confirmed this measurement by observing neutrinos from the Sun. The SNO+ experiment is intended to study the nature of neutrino masses by replacing the heavy water used in SNO with scintillator. The main goal of the experiment is to search for neutrinoless double-beta decay within 130Te. The SNO+ detector is much more sensitive to radioactive contamination than the SNO experiment. For this reason an external LED calibration system has been developed so the detector can be calibrated without risking contamination of the scintillator volume. This thesis describes the commissioning of this calibration system and its performance during the water phase of SNO+. The scintillator volume is separated from the surrounding detector via an acrylic vessel. As scintillator is less dense than water the position of the vessel is expected to shift throughout the lifetime of SNO+. A method to determine the position of the vessel using the external LED system is detailed as well as its performance. A measurement of the scattering length of the water surrounding the acrylic vessel using the same LED system is also presented. Calibration of the detector will also be performed using sources deployed within the vessel, and a study on the angular distribution of light from these sources and the effect of hardware upgrades is also presented. During the lifetime of the SNO+ experiment, the detector will be sensitive to neutrinos emitted from a supernovae within the Milky Way. A software framework was developed to accurately simulate the main interaction channels for supernova neutrinos within SNO+. The software was used to determine the burst trigger effciency during the water phase as well as a procedure to follow in the case of the burst. One outstanding problem in the field of neutrino physics is the neutrino mass hierarchy; whether there are two heavy and one light or two light and one heavy neutrino mass eigenstates. Neutrinos from a supernova burst may be able to solve this problem. A simple study is performed to determine the sensitivity of various detectors. The same analysis is performed using the aforementioned software to explore any systematic effects which may alter the sensitivity

Effect of Partial Saturation on Liquefaction Triggering

To correlate liquefaction resistance with degree of saturation for characteristics Christchurch soils including sands with fines and silts. To incorporate the effects of saturation in simplified procedures for liquefaction assessment. Provide basis for quantifying the effects of partial saturation in advanced seismic analysis

Comparing adaptive management and transition management

For addressing and governing long-term socialecological change two different framworks are available: transition management and adaptive management. They emphasise the roles of social learning and stakeholder participation in different contexts

Organisations, race and trauma

SIGNPOSTING RESOURCES IN THE WAKE OF GEORGE FLOYD’S DEATH This brief guide is intended as a ‘first stop’ resource to help individuals understand: a) A brief outline of Institutional Racism so that individuals can read up and better inform themselves about the context– with the caveat that some content might be distressing b) The role of Activism c) An explanation of Racially Traumatic Events which affect people at work and in their private lives d) Some Practical Strategies to help individuals cope with the trauma they have witnessed e) Further resources about Tackling Racism in Education and decolonising the curriculum which contain advice, facts and guidance. Much of this information may be of interest to the wider community

Estimating the cost-effectiveness of nutrition supplementation for malnourished, HIV-infected adults starting antiretroviral therapy in a resource-constrained setting

Abstract Background Low body mass index (BMI) individuals starting antiretroviral therapy (ART) for HIV infection in sub-Saharan Africa have high rates of death and loss to follow-up in the first 6 months of treatment. Nutritional supplementation may improve health outcomes in this population, but the anticipated benefit of any intervention should be commensurate with the cost given resource limitations and the need to expand access to ART in the region. Methods We used Markov models incorporating historical data and program-wide estimates of treatment costs and health benefits from the Zambian national ART program to estimate the improvements in 6-month survival and program retention among malnourished adults necessary for a combined nutrition support and ART treatment program to maintain cost-effectiveness parity with ART treatment alone. Patients were stratified according to World Health Organization criteria for severe (BMI <16.0 kg/m2), moderate (16.00-16.99 kg/m2), and mild (17.00-18.49 kg/m2) malnutrition categories. Results 19,247 patients contributed data between May 2004 and October 2010. Quarterly survival and retention were lowest in the BMI <16.0 kg/m2 category compared to higher BMI levels, and there was less variation in both measures across BMI strata after 180 days. ART treatment was estimated to cost $556 per year and averted 7.3 disability-adjusted life years. To maintain cost-effectiveness parity with ART alone, a supplement needed to cost$10.99 per quarter and confer a 20% reduction in both 6-month mortality and loss to follow-up among BMI <16.0 kg/m2 patients. Among BMI 17.00-18.49 kg/m2 patients, supplement costs accompanying a 20% reduction in mortality and loss to follow-up could not exceed $5.18 per quarter. In sensitivity analyses, the maximum permitted supplement cost increased if the ART program cost rose, and fell if patients classified as lost to follow-up at 6 months subsequently returned to care. Conclusions Low BMI adults starting ART in sub-Saharan Africa are at high risk of early mortality and loss to follow-up. The expense of providing nutrition supplementation would require only modest improvements in survival and program retention to be cost-effective for the most severely malnourished individuals starting ART, but interventions are unlikely to be cost-effective among those in higher BMI strata