NOACs versus warfarin for stroke prevention in patients with AF : a systematic review and meta-analysis

Acknowledgments Revman software was used for meta-analysis, a free download from the Cochrane Collaboration. GRADE pro software was used to formulate the GRADE summary of findings table, a free download from the GRADE working group.Peer reviewedPublisher PD

TRIBOLOGICAL CHARACTERISATION AND MODELLING OF PREMIUM TUBULAR CONNECTIONS

Premium tubular connections (sometimes referred to as rotary shouldered thread connections), are commonly used to complete a production string in a well in the oil and gas industry. These are attached to threaded pipe ends using a bucking unit and a pre-defined torque value. The torque value is calculated using the coefficient of friction between the two surfaces and a well-known torque equation. The existing technology relies on the coefficient of friction approximated by interpolation, or extrapolation, of empirical data. This may become inaccurate due to the variation of surface finish and/or operation conditions and lead to over or under torque of the connections. A failure such as a leaking connection can result in high financial implications as well as environmental ones. The project was aimed to develop a bench test which adequately represents field conditions. This benchmark test was then used to investigate how CoF was affected by changes in the main variables so that these variables can be better controlled. Therefore, a propriety laboratory test system was developed to allow measurements of friction and galling under these conditions and to examine the sensitivity of friction to initial surface topography, contact pressure, sliding speed and lubricant type. Samples were produced to represent variables which were possible within the oil and gas industry. A set of data was produced to identify the different frictional values for each combination of variables. The results showed that the initial surface topography and the burnishing in repeated sliding have significant effects on friction. iv In order to understand the correlation between the effects of initial surface roughness and burnishing during the sliding process on the coefficient of friction, a theoretical approach was taken to produce a mathematical model whichutilised the data from the laboratory testing. This gave predictions of the wear, roughness and friction with sliding distance. This data was then compared to the physical testing and found to be in line with the results. The results helped to understand how friction is related to external circumstances in the operation of premium tubular connections.Hunting Energy Service

A Cultural Observation Project for Outbound Students to France

This project contains guided question sheets and topics for discussions on cultural values which I developed while leading a summer Outbound group to France. They are designed to help students who are in an immersion or homestay siatuation to focus their attention on the various aspects of everyday life in France, to make careful observations, to share and compare their findings with other group members with the goal of gaining greater understanding of and appreciation for the French cultur

Effects of Acid Mine Drainage and Acid Precipitation on Leaf Litter Breakdown Rates in Appalachian Headwater Streams

Acid precipitation and acid mine drainage have dramatically altered chemical conditions and biological assemblages in streams throughout the central Appalachians. Effects of acidification on functional stream processes such as organic matter decomposition, however, remain poorly understood. The objectives of this study were to: (1) quantify differences in organic matter decomposition among reference streams, streams impacted by acid precipitation, and streams impacted by acid mine drainage; and (2) determine if lowered decomposition rates are the result of reduced microbial activity or altered invertebrate shredder assemblages or both. I quantified water chemistry, organic matter decomposition, microbial activity, and macroinvertebrate community structure in 15 headwater streams in the central Appalachian ecoregion (5 circumneutral reference, 5 acid mine drainage, and 5 acid precipitation). Decomposition rates were quantified from leaf packs deployed for a period of 120 days over three seasons. Water chemistry was sampled in conjunction with decomposition trials. Benthic invertebrate communities were sampled in spring and fall. Microbial activity was measured as total microbial community respiration and ergosterol content. Acid mine drainage resulted in dramatically reduced shredder assemblages, reduced microbial activity and reduced overall organic matter decomposition. Acid precipitation resulted in altered shredder assemblages, reduced microbial respiration and diminished organic matter decomposition, but not as severely as seen in acid mine drainage streams. Overall, decomposition rates were more strongly correlated with microbial respiration and ergosterol concentration than shredder community composition. However, shifts in shredder assemblages, including the loss of acid sensitive voracious shredders, such as Lepidosotoma, Limnephilidae, Petronarcys, Gammarus, and Decopoda, also is likely responsible for the reduction in organic matter processing ability in acid impacted streams. Our results provide further evidence that restoration of acidic headwater Appalachian streams is needed in order to effectively manage conditions in larger aquatic ecosystems downstream

The evolution of shelter: ecology and ethology of chimpanzee nest building

Human beings of all cultures build some form of shelter, and the global distribution of Homo sapiens depends on this basic trait. All great apes (chimpanzee, bonobo, gorilla, and orangutan) build analogous structures (called nests or beds) at least once a day throughout their adult lives, which suggests that this elementary technology was present before the hominid lines separated. This thesis investigates the variability and function of specifically wild chimpanzee shelters. I compared characteristics of chimpanzee nests, nesting trees, nest shape, and architecture in two savanna-dwelling populations on opposite sides of Africa: Fongoli, Senegal, and Issa, Tanzania. Savanna habitats are the most extreme habitats in which chimpanzees survive today, and may represent a similar environment to that in which early hominins evolved in the Plio-Pleistocene (Chapter 2). Investigating variation in nest-building within and between these two extreme habitats made it possible to tackle hypotheses of the shelter function of nests (Chapter 3). The influence of environment, specifically the role of protection from disease vectors and fluctuating temperatures, was assessed through a novel experiment in which I slept overnight in arboreal chimpanzee nests and on the bare earth (Chapter 4). To assess whether or not nests serve as an anti-predation function, I compared nesting in Issa, where predators are abundant, to Fongoli, where they are absent (Chapter 5). I provided further support for the thermoregulatory function of nests by showing that chimpanzees build more insulating nests in adverse weather conditions (Chapter 6). Nest-building is a learned behaviour, but its ontogeny is little known. I investigated social sources of variation in nest building in Fongoli to examine whether sex and age differences exist in nest building duration, nest position, shape and architecture (Chapter 7). Finally, ecosystem engineering is a consequence of animal construction, from ants to humans. I investigated use-wear traces around nests to assess niche construction of nest- building. I showed that chimpanzees repeatedly re-used these specific nest-spots within trees, which are pre-fabricated for future building through repeated pruning and shaping of these structures (Chapter 8). Nest building in great apes may be the foundation of constructivity in hominids. This thesis describes proximate functions and influences on nest-building variation in wild chimpanzees that help to model the evolution of shelter in hominids.This work was supported by the Carnegie Trust for Universities of Scotland (Carnegie Scholarship, Carnegie Research Grant), Corpus Christi College for a Taylor Bursary, Harold Hyam Wingate Foundation, International Primatological Society, L.S.B. Leakey Foundation, and the Wenner Gren Foundation