Image intensifier studies of low intensity triboluminescence, electroluminescence and photoluminescence of solids

A four-stage magnetically focused image intensifier tube (IIT) with an optical power gain of about 106 was used in both spatial and spectral investigations of solids. The spectral studies involved the design and construction of a spectrograph to disperse light across the input photocathode of the IIT. Spectra were then amplified by the IIT and displayed on the output phospher where they were photographically recorded. The system was intensity corrected and used to measure the triboluminescence (TL) spectra from small quantities (- 10 grams) of material. The TL spectra of minerals including amethyst, zircon, and various calcites and fluorites were recorded for the first time with high spectral resolution. Origins of these TL spectra were investigated, and many were correlated with appropriate term diagrams. The results are discussed following a detailed and critical review of the literature. Light emission from cutting a number of glasses and polymers on a diamond saw was also recorded and the (continuum like) spectra obtained were compared with black body radiation (at the temperature estimated to occur at a crack tip due to release of plastic deformation energy). Differences were noted in some cases between the TL which occurred at fracture and the light emission of the same samples when cut on the diamond saw. These differences are discussed with reference to the photoluminescence spectra of the samples. Thermoluminescence spectra were also recorded, again using an IIT spectrograph, and the results were compared with TL of similar specimens. A spatial study of semiconductors was made by projecting the image of a small area (typically 50 um2) of the specimen, using a microscope, onto the input photocathode of the IIT. The high optical power gain of the system was utilized in a 'spatial investigation of semiconductor electroluminescence (EL) and photoluminescence (PL). The EL of GaP and Ga1-xAlxAs (x = 0.35 and 0.52) was recorded and the EL of the latter was compared with cathodoluminescence of the same specimen to highlight the complementary nature of the techniques. The homogeneity of the PL of a sample of amorphous silicon was studied at 77K in a specially constructed cryostat. The application of the method to other homogeneity measurements is discussed

A weakly singular integral equation approach for water wave problems

EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Essays on economic integration

This thesis presents the findings of three empirical chapters related to economic integration. In the first of these chapters, we run a linear probability model (LPM) on a pooled sample of 106 countries, for the years 1960–2011; and on two sub-samples, one between 1960 and 1996 and the other between 1997 and 2011. This separation helps us determine whether the economic determinants of preferential trade agreements have changed, and our core result is that they have not. Second, for a panel of 180 countries and the years 1995–2012, we run Poisson regressions under three hypotheses, exploring whether integration lowers trade costs. We find that (i) forming trade agreements, (ii) deepening integration, and (iii) staying in trade agreements all significantly lowers trade costs. Our final empirical chapter explores the impact of regional integration on agricultural production in Sub-Saharan Africa using least squares estimates on a panel of 45 countries over the 1961–2014 time horizon. We find no effect of regional integration on agricultural production and, to help us understand why, we again turn to trade costs and Poisson estimation: for 44 SSA countries over the 1995–2012 time horizon, we find that regional integration has not lowered agricultural trade costs in Sub-Saharan Africa, but it has done so for the World

Interleukin 2 Receptor Antagonists for Kidney Transplant Recipients

Background: Interleukin 2 receptor antagonists (IL2Ra) are used as induction therapy for prophylaxis against acute rejection in kidney transplant recipients. Use of IL2Ra has increased steadily, with 38% of new kidney transplant recipients in the United States, and 23% in Australasia receiving IL2Ra in 2002. Objectives: This study aims to systematically identify and summarise the effects of using an IL2Ra, as an addition to standard therapy, or as an alternative to other antibody therapy. Search strategy: The Cochrane Renal Group's specialised register (June 2003), the Cochrane Controlled Trials Register (in The Cochrane Library issue 3, 2002), MEDLINE (1966-November 2002) and EMBASE (1980-November 2002). Reference lists and abstracts of conference proceedings and scientific meetings were hand-searched from 1998-2003. Trial groups, authors of included reports and drug manufacturers were contacted. Selection criteria: Randomised controlled trials (RCTs) in all languages comparing IL2Ra to placebo, no treatment, other IL2Ra or other antibody therapy. Data collection and analysis: Data was extracted and quality assessed independently by two reviewers, with differences resolved by discussion. Dichotomous outcomes are reported as relative risk (RR) with 95% confidence intervals (CI). Main results: One hundred and seventeen reports from 38 trials involving 4893 participants were included. Where IL2Ra were compared with placebo (17 trials; 2786 patients), graft loss was not significantly different at one (RR 0.83, 95% CI 0.66 to 1.04) or three years (RR 0.88, 95% CI 0.64 to 1.22). Acute rejection (AR) was significantly reduced at six months (RR 0.66, 95% CI 0.59 to 0.74) and at one year (RR 0.67, 95% CI 0.60 to 0.75). At one year, cytomegalovirus (CMV) infection (RR 0.82, 95% CI 0.65 to 1.03) and malignancy (RR 0.67, 95% CI 0.33 to 1.36) were not significantly different. Where IL2Ra were compared with other antibody therapy no significant differences in treatment effects were demonstrated, but adverse effects strongly favoured IL2Ra. Reviewer's conclusions: Given a 40% risk of rejection, seven patients would need treatment with IL2Ra to prevent one patient having rejection, with no definite improvement in graft or patient survival. There is no apparent difference between basiliximab and daclizumab. IL2Ra are as effective as other antibody therapies and with significantly fewer side effect

The Spitzer c2d Survey of Large, Nearby, Interstellar Clouds. VIII. Serpens Observed with MIPS

We present maps of 1.5 deg^2 of the Serpens dark cloud at 24, 70, and 160 μm observed with the Spitzer Space Telescope MIPS camera. We describe the observations and briefly discuss the data processing carried out by the c2d team on these data. More than 2400 compact sources have been extracted at 24 μm, nearly 100 at 70 μm, and four at 160 μm. We estimate completeness limits for our 24 μm survey from Monte Carlo tests with artificial sources inserted into the Spitzer maps. We compare source counts, colors, and magnitudes in the Serpens cloud to two reference data sets: a 0.50 deg^2 set on a low-extinction region near the dark cloud, and a 5.3 deg^2 subset of the SWIRE ELAIS N1 data that was processed through our pipeline. These results show that there is an easily identifiable population of young stellar object candidates in the Serpens cloud that is not present in either of the reference data sets. We also show a comparison of visual extinction and cool dust emission illustrating a close correlation between the two and find that the most embedded YSO candidates are located in the areas of highest visual extinction

A multi-model approach to stakeholder engagement in complex environmental problems

We describe the different types of models we used as part of an effort to inform policy-making aiming at the management of the Ningaloo coast in the Gascoyne region, Western Australia. This provides an overview of how these models interact, the different roles they cover, how they fit into a full decision making process and what we learnt about the stakeholders involved in our project via their use. When modelling is explicitly used to address socio-ecological issues, the key determinant of success is whether the models, their results and recommendations are taken up by stakeholders; such uptake in turn depends on addressing stakeholders’ concerns, on engaging them in the project, on ensuring they feel ownership of the decision process at large, and that they understand and trust the modelling effort. This observation has guided our approach and has resulted in treating ‘building a model’ as the catalyst, rather than the final aim, of the process. In other words, extensive interactions in order to introduce, showcase, discuss and tune the model used for final decision making have represented both a requirement and an opportunity to ensure (i) model relevance, (ii) its acceptance, (iii) that all information available in the stakeholder team was accounted for and (iv) that stakeholders holding different levels of understanding of modelling, what it does and what it can provide to decision-making could develop an informed opinion on its use. To fulfil these roles we developed five broad classes of models: conceptual models, toy-models, singlesystem models, shuttle-models and a full-system model. In conceptual models the main drivers of a system are highlighted for subsequent representation as components of the full-system model. This usually results in a diagram summarising our understanding of how the system works. In toy-models a problem is simplified in such a way that only a handful of components are included. The purpose of these models is mostly educational: we want to understand how each component affects the problem and in order to achieve this, we temporarily renounce a satisfactory understanding of the overall problem. In single-system models we include a fairly detailed representation of a single component of the system (in our case recreational fishing and tourism); these models can be used to introduce stakeholders to modelling, provide temporary results from the study of a single activity, which will feed into the development of the final full-system model, or address sector-specific issues. In shuttle-models, we include the minimum number of processes we believe are crucial for a basic understanding of the overall problem. We know these models are still too simple for full system description, but they provide a sufficient understanding to enable us to contemplate, build and use the more complex models needed for full problem description. The term ‘shuttle’ refers to taking us from a minimum to a full description of the problem, a journey which is necessary both to developers in model definition and parameterisation and to stakeholders in the interpretation of the final full-system model results. Finally, the full-system model includes all information collected through the project and addresses all scenarios of stakeholders concern, and whose definition has been greatly eased by use of the ‘simpler’ models. As an example, a conceptual model may identify fishing and tourism as the main drivers of a region; a toymodel may describe how catches affect fish stocks; a single-system model may include the effect of gear, regulations and other processes affecting recreational fishing; a shuttle-model may include a simplified representation of the interaction between fishing, tourism, and infrastructure development on the overall health of the local ecosystem; this will gradually ‘take’ us to comprehend the ‘full’ model which may include tourism pressure, fish market values, climate effect, larger food-webs, etc