Singularity theorems from weakened energy conditions

We establish analogues of the Hawking and Penrose singularity theorems based on (a) averaged energy conditions with exponential damping; (b) conditions on local stress-energy averages inspired by the Quantum Energy Inequalities satisfied by a number of quantum field theories. As particular applications, we establish singularity theorems for the Einstein equations coupled to a classical scalar field, which violates the strong energy condition, and the nonminimally coupled scalar field, which also violates the null energy condition.Comment: v3 18 pages. Minor correction to the proof of Lemma 3.1; results are unchanged. Final version to appear in Class Quantum Gra

Non-Radiative Processes and Vibrational Pumping in Surface-Enhanced Raman Scattering

The main focus of this thesis was the physical interpretation of the pumping cross-section. This was achieved by performing a statistical analysis of single molecule vibrational pumping events in which both the SERS and pumping cross-sections could be measured simultaneously. Samples were constructed in which small aggregates of silver colloids were evenly distributed on a dry surface. The sample was then cooled to 77K so that the main mechanism for creating a vibrational population was through Stokes scattering. Spatial mappings were then performed which measured how the SERS spectrum varied with position on the sample and the single molecule events were identified. The SERS cross-sections were determined from the Stokes intensity while the pumping cross-sections were determined from the ratio of the anti-Stokes and Stokes peaks. It was observed that the pumping cross-section was often significantly larger than the SERS cross-section, as much as four orders of magnitude in some cases. Several attempts were made to explain this discrepancy including the possibility of the surface plasmon resonance favouring anti-Stokes scattering, underestimated lifetimes for the vibrational modes, and additional pumping from fluorescence. However, the most likely candidate was non-radiative Stokes scattering by the observed molecule which would increase the vibrational population but would not increase the Stokes intensity. To estimate the proportion of scattered light that is radiative or non-radiative, single molecule measurements were performed under both surface-enhanced and unmodified conditions. By comparing the fluorescence and Raman intensities under these scenarios, it was possible to estimate the radiative and non-radiative enhancement factors. It was found that the non-radiative SERS cross-section was typically much larger than the radiative cross-section for samples consisting of aggregated silver colloids. The discrepancy between the pumping and SERS cross-section (which is the radiative cross-section) could therefore be explained by non-radiative scattering dominating the creation of the vibrational population, along with an additional contribution due to the plasmon resonance favouring certain vibrational modes. Furthermore, the lifetime of a molecule after it has been excited to the first electronic state was estimated to be as short as 25 fs. It would be impossible to measure lifetimes of this order of magnitude in single molecules using time-resolved techniques. Furthermore, to the very best of our knowledge, this is the first time that an experimental determination of the non-radiative SERS cross-section has been made

Ecotourism in British Columbia : theory and practice

Ecotourism is a concept of admirable ideals, but has lacked a mechanism to relate these ideals from theory to practice. This thesis provides such a mechanism to identify ecotourism in practice. This was achieved by: Assessing the concept of ecotourism as a form of sustainable development. Identifying 'key elements' which constitute ecotourism in theory, and relating them to practice in British Columbia. Deciding if ecotourism exists in British Columbia Reviewing and assessing the actions and initiatives of administration toward sustainable development (and potentially ecotourism) in British Columbia. A review of sustainable development and ecotourism from a theoretical perspective provide a model for assessing the implementation of sustainable tourism development initiatives in British Columbia. It also provides a basis from which to assess the ecotourism concept. For ecotourism, the ideals and features that are used (o describe the concept are collectively identified. These are termed ecotourisms 'key elements'. They are divided into three categories, firstly a participant perspective which involves assessment of motivation, intensity, education, participation; and behaviour, secondly an operational perspective of environmentally sensitive management, and thirdly administrative requirements of a planned and protected operating environment The 'key elements' are used to analyse a selection of nature based tourism operations from the High Country and Vancouver Island Tourism Regions of British Columbia. The 'key element' method of analysis is found to be effective for identifying ecotourism in practice. However a decisive 'key element' is considered to be a protected operating environment. While administrative initiatives in British Columbia to improve protection of operating environments are comprehensive, the traditional resource extraction industries of the province present a challenge that tourism has difficulty competing against. The strategy to meet this challenge rests in the Tourism Ministry gaining a legislative mandate in resource management. This thesis concludes that the success of this strategy is largely dependent on unified and effective lobbying from the tourism industry as a whole to the government, and more generally on a cooperative environment between all government administrations that utilise the natural resources of the Province

Do Coping Motives Moderate Daily Mood-Drinking Covariation: Disentangling a Paradox

The current study examines a paradox in the college student alcohol use literature where drinking to cope with negative affect (DTC) is concurrently and prospectively linked to problems with alcohol; however, experience sampling and daily diary studies have either failed to find a link between affect and drinking within a day, or found the relationship only under specific circumstances. Participants were 124 college students from a large Southeastern university. These individuals completed an online daily diary protocol for two weeks to report daily emotions, drinking motives and alcohol consumption. A series of HGLM analyses were conducted to test study hypotheses. The influence of self-awareness on the moderating effects of dispositional DTC on mood-drinking covariation were considered in two separate models, for global negative affect using the DTC subscale of Cooper's drinking motives questionnaire (1994) and also for sadness using a sadness specific measure of DTC. Neither the standard dispositional DTC model nor the dispositional sadness specific models were significant. DTC was also assessed as a daily process. The moderating effects of global negative affect and sadness specific daily drinking motives on mood-drinking covariation on drinking days was tested and a significant interaction between daily sadness motives, sad mood, and quantity of alcohol consumed was found. At relatively higher levels of daily sadness DTC individuals drank more when experiencing more sad mood and drank less when experiencing less sad mood, whereas those relatively low in DTC drank less on days with more sad mood and drank more on days with less sad mood. The global negative affect model was not supported. Post-hoc analyses were conducted to examine potential methodological explanations for the lack of findings in the three of the four models tested. Strengths, limitations, clinical implications and future directions are discussed

Predicting Response of An Aquifer System to Uranium Extraction Oakville Aquifer, Texas Coastal Plain

The initiation or expansion of uranium mining in the Texas Gulf Coastal Plain, utilizing both open-pit and in situ leach methods, raises concerns about the potential impact on groundwater within mineralized aquifers. Understanding the hydrodynamics, hydrochemical evolution, and matrix geochemistry of these aquifers is essential for implementing effective protection and restoration measures. To address these issues, the Oakville Sandstone, a significant Coastal Plain aquifer, was chosen as a natural laboratory. The Oakville Sandstone comprises deposits from several major fluvial systems. The geometry and composition of these facies, along with superimposed structures and topography, play crucial roles in determining groundwater flux, aquifer transmissivity, and regional hydrochemical evolution. Groundwater flux patterns, especially in the shallow portions suitable for mining, can be highly complex and influenced by various factors. Studying the interrelationships among hydrodynamics, hydrochemical evolution, and matrix geochemistry in the Oakville Sandstone will provide insights into the effectiveness of mining technology in coastal plain aquifer systems. This research will aid in developing strategies to mitigate potential impacts on groundwater quality and ensure sustainable uranium mining practices in the region.Bureau of Economic Geolog

Brazing development and interfacial metallurgy study of tungsten and copper joints with eutectic gold copper brazing alloy

Current proposals for the divertor component of a thermonuclear fusion reactor include tungsten and copper as potentially suitable materials. This paper presents the procedures developed for the successful brazing of tungsten to oxygen free high conductivity (OFHC) copper using a fusion appropriate gold based brazing alloy, Orobraze 890 (Au80Cu20). The objectives were to develop preparation techniques and brazing procedures in order to produce a repeatable, defect free butt joint for tungsten to copper. Multiple brazing methods were utilised and brazing parameters altered to achieve the best joint possible. Successful and unsuccessful brazed specimens were sectioned and analysed using optical and scanning electron microscopy, EDX analysis and ultrasonic evaluation. It has been determined that brazing with Au80Cu20 has the potential to be a suitable joining method for a tungsten to copper joint

Latent Hardeners for the Assembly of Epoxy Composites

Large-scale composite structures are commonly joined by secondary bonding of molded-and-cured thermoset components. This approach may result in unpredictable joint strengths. In contrast, assemblies made by co-curing, although limited in size by the mold, result in stable structures, and are certifiable for commercial aviation because of structural continuity through the joints. Multifunctional epoxy resins were prepared that should produce fully-cured subcomponents with uncured joining surfaces, enabling them to be assembled by co-curing in a subsequent out-of-autoclave process. Aromatic diamines were protected by condensation with a ketone or aldehyde to form imines. Properties of the amine-cured epoxy were compared with those of commercially available thermosetting epoxy resins and rheology and thermal analysis were used to demonstrate the efficacy of imine protection. Optimum conditions to reverse the protecting chemistry in the solid state using moisture and acid catalysis were determined. Alternative chemistries were also investigated. For example, chain reaction depolymerization and photoinitiated catalysts would be expected to minimize liberation of volatile organic content upon deprotection and avoid residual reactive species that could damage the resin. Results from the analysis of protected and deprotected resins will be presented

Core Academic Language Skills (CALS): An expanded operational construct and a novel instrument to chart school-relevant language proficiency in per-adolescent and adolescent learners.

Beyond academic vocabulary, the constellation of skills that comprise academic language proficiency has remained imprecisely defined. This study proposes an expanded operationalization of this construct referred to as ‘Core Academic Language Skills’ (CALS). CALS refers to the knowledge and deployment of a repertoire of language forms and functions that co-occur with school learning tasks across disciplines. Using an innovative instrument, we explored CALS in a cross-sectional sample of 235 students in grades 4-8. Results revealed between- and within-grade variability in CALS. Psychometric analyses yielded strong reliability and supported the presence of a single CALS factor, which was found to be predictive of reading comprehension. Findings suggest that the CALS construct and instrument appear promising for exploring students' school-relevant language skills

Haematological abnormalities in new onset rheumatoid arthritis and risk of common infections:a population-based study

Objectives To describe the prevalence of haematological abnormalities in individuals with rheumatoid arthritis (RA) at the point of diagnosis in primary care, and the associations between haematological abnormalities, vaccinations and subsequent risk of common infections. Methods We studied 6,591 individuals with newly diagnosed RA between 2004 and 2016 inclusive using the UK Royal College of General Practitioners (RCGP) Research and Surveillance Centre (RSC) primary care database. The prevalence of haematological abnormalities at diagnosis (anaemia, neutropenia and lymphopenia) was established. Cox proportional hazards models were used to evaluate i) the association between each haematological abnormality and time to common infections; ii) the influence of vaccination status (influenza and pneumococcal vaccine) on time to common infections in individuals with RA, compared with a matched cohort of individuals without RA. Results Anaemia was common at RA diagnosis (16.1% of individuals), neutropenia (0.6%) and lymphopenia (1.4%) less so. Lymphopenia and anaemia were associated with increased infection risk (respective hazard ratios (HR) 1.18 (95%CI 1.08-1.29); HR 1.37 (95%CI 1.08-1.73)). There was no evidence of an association between neutropenia and infection risk (HR 0.94 (95%CI 0.60-1.47). Pneumonia was much more common in individuals with early RA compared with controls. Influenza vaccination was associated with reduced risk of influenza-like illness only for individuals with RA (HR 0.58 (95% CI 0.37-0.90). Conclusion At diagnosis, anaemia and lymphopenia, but not neutropenia, increase the risk of common infections in individuals with RA. Our data support the effectiveness of the influenza vaccination in individuals with RA.</p