271 research outputs found
An evaluation of remote sensing techniques for the detection of archaeological features
The thesis evaluates the potential for using multiple remote sensing techniques to identify archaeological features buried beneath vegetation. The research is carried out on data acquired by the Natural Environmental Research Council (henceforth NERC), who have provided multispectral, LIght Detection and Ranging (henceforth LİDAR) and high resolution colour aerial photographic data. The returns from these techniques are compared with ground-based geophysical survey data carried out by the Landscape Research Centre (henceforth LRC) on four major projects funded by English Heritage (henceforth EH), as well as aerial photographs collected by the LRC. The methodology adopted for this research uses primarily qualitative techniques, where images from different forms of remote sensing are processed, georeferenced and then compared for their ability to identify archaeological features. A process has been developed where the returns from each form of remote sensing are interpreted and then digitised as vector polygons with individual database entries for each polygon, which allows a direct comparison between the different datasets to be conducted. The timing of the data acquisition is shown to be critical if the data is to be used for small scale anomaly detection, as is the case with archaeological features. This is particularly true for airborne sensors, although the returns from ground-based geophysical surveys can also be affected if carried out under unfavourable circumstances. It was established that the different underlying drift geologies of the Vale of Pickering also affected the returns from remote sensing sources, with the calcareous and sandy zones of the southern part of the research area generally (though not exclusively) providing better results than the more alluvial zones to the north. The use of different forms of airborne remote sensing and geophysical survey are demonstrated to be complementary, with each form of remote sensing identifying different, though not always exclusively different, archaeological anomalies
Duration of consultant experience and patient outcome following acute medical unit admission.:An observational cohort study
Arras 200: revisiting Britain's most famous Iron Age cemetery
In the bicentenary year of its excavation, remote sensing has revealed, for the first time, the full extent of this iconic type-site Iron Age cemetery and its landscape context in East Yorkshire. A total of 23ha was surveyed, revealing new insights concerning the burial ground and damage through modern farming
A redetermination at low temperature of the structure of triethylammonium bromide
The structure of the title compound, C6H16N+·Br−, was determined at low temperature and the cell dimensions were comparable to those reported for room-temperature studies [James, Cameron, Knop, Newman & Falp, (1985). Can. J. Chem.
63, 1750–1758]. Initial analysis of the data led to the assignment of P31
c as the space group rather than P63
mc as reported for the room-temperature structure. Careful examination of the appropriate |F
o| values in the low-temperature data showed that the equalities |F(
kl)| = |F(h
l)| and |F(hkl)| = |F(hk
)| did not hold at low temperature, confirming P31c as the appropriate choice of space group. As a consequence of this choice, the N atom sat on a threefold axis and the ethyl arms were not disordered as observed at room temperature. The crystal studied was an inversion twin with a 0.68 (3):0.32 (3) domain ratio
Tissue Doppler imaging following paediatric cardiac surgery : early patterns of change and relationship to outcome
In this study, tissue Doppler imaging (TDI) was used to assess changes in ventricular function following repair of congenital heart defects. The relationship between TDI indices, myocardial injury and clinical outcome was explored. Forty-five children were studied; 35 withcardiac lesions and 10 controls. TDI was performed preoperatively, on admission to paediatric intensive care unit (PICU) and day 1. Regional myocardial Doppler signals were acquired from the right ventricle (RV), left ventricle (LV) and septum. TDI indices included: peak systolicvelocities, isovolumetric velocities (IVV) and isovolumetric acceleration (IVA). Preoperatively, bi-ventricular TDI velocities in the study groupwere reduced compared with normal controls. Postoperatively, RV velocities were significantly reduced and this persisted to day-1 (PreOp vs. PICU and day-1: 7.7+2.2 vs. 3.4+1.0, P < 0.0001 and 3.55+1.29, P < 0.0001). LV velocities initially declined but recovered towards baseline by day-1 (PreOp vs. PICU: 5.31+1.50 vs. 3.51+1.23, P < 0.0001). Isovolumetric parameters in all regions were reduced throughout the postoperative period. Troponin-I release correlated with longer X-clamp times (r=0.82, P < 0.0001) and reduced RV velocities (r=0.42, P=0.028). Reduced pre- and postoperative LV velocities correlated with longer ventilation (PreOp: r=0.54, P=0.002; PostOp: r=0.42, P=0.026). This study identified reduced postoperative RV velocities correlated with myocardial injury while reduced LV TDI correlated with longer postoperative ventilation
Comprehensive Assessment of Sleep Duration, Insomnia and Brain Structure within the UK Biobank Cohort
Comprehensive Assessment of Sleep Duration, Insomnia and Brain Structure within the UK Biobank Cohort
STUDY OBJECTIVES: To assess for associations between sleeping more than or less than recommended by the National Sleep Foundation (NSF), and self-reported insomnia, with brain structure. METHODS: Data from the UK Biobank cohort were analysed (N between 9K and 32K, dependent on availability, aged 44 to 82 years). Sleep measures included self-reported adherence to NSF guidelines on sleep duration (sleeping between 7 and 9 hours per night), and self-reported difficulty falling or staying asleep (insomnia). Brain structural measures included global and regional cortical or subcortical morphometry (thickness, surface area, volume), global and tract-related white matter microstructure, brain age gap (difference between chronological age and age estimated from brain scan), and total volume of white matter lesions. RESULTS: Longer-than-recommended sleep duration was associated with lower overall grey and white matter volumes, lower global and regional cortical thickness and volume measures, higher brain age gap, higher volume of white matter lesions, higher mean diffusivity globally and in thalamic and association fibers, and lower volume of the hippocampus. Shorter-than-recommended sleep duration was related to higher global and cerebellar white matter volumes, lower global and regional cortical surface areas, and lower fractional anisotropy in projection fibers. Self-reported insomnia was associated with higher global grey and white matter volumes, and with higher volumes of the amygdala, hippocampus and putamen. CONCLUSIONS: Sleeping longer than recommended by the NSF is associated with a wide range of differences in brain structure, potentially indicative of poorer brain health. Sleeping less than recommended is distinctly associated with lower cortical surface areas. Future studies should assess the potential mechanisms of these differences and investigate long sleep duration as a putative marker of brain health
Associations between diabetes and both cardiovascular disease and all-cause mortality are modified by grip strength: evidence from UK Biobank, a prospective population-based cohort study
OBJECTIVE Grip strength and diabetes are predictors of mortality and cardiovascular disease (CVD), but whether these risk factors interact to predispose to adverse health outcomes is unknown. This study determined the interactions between diabetes and grip strength and their association with health outcomes.
RESEARCH DESIGN AND METHODS We undertook a prospective, general population cohort study by using UK Biobank. Cox proportional hazards models were used to explore the associations between both grip strength and diabetes and the outcomes of all-cause mortality and CVD incidence/mortality as well as to test for interactions between diabetes and grip strength.
RESULTS 347,130 UK Biobank participants with full data available (mean age 55.9 years, BMI 27.2 kg/m2, 54.2% women) were included in the analysis, of which 13,373 (4.0%) had diabetes. Over a median follow-up of 4.9 years (range 3.3–7.8 years), 6,209 died (594 as a result of CVD), and 4,301 developed CVD. Participants with diabetes were at higher risk of all-cause and CVD mortality and CVD incidence. Significant interactions (P < 0.05) existed whereby the risk of CVD mortality was higher in participants with diabetes with low (hazard ratio [HR] 4.05 [95% CI 2.72, 5.80]) versus high (HR 1.46 [0.87, 2.46]) grip strength. Similar results were observed for all-cause mortality and CVD incidence.
CONCLUSIONS Risk of adverse health outcomes among people with diabetes is lower in those with high grip strength. Low grip strength may be useful to identify a higher-risk subgroup of patients with diabetes. Intervention studies are required to determine whether resistance exercise can reduce risk
A general theory of equilibrium selection in games. Chapter 5: The solution concept
Harsanyi JC, Selten R. A general theory of equilibrium selection in games. Chapter 5: The solution concept. Working Papers. Institute of Mathematical Economics. Vol 132. Bielefeld: Center for Mathematical Economics; 1984
Effect of apolipoprotein E polymorphism on cognition and brain in the Cambridge Centre for Ageing and Neuroscience cohort.
Polymorphisms in the apolipoprotein E (APOE) gene have been associated with individual differences in cognition, brain structure and brain function. For example, the ε4 allele has been associated with cognitive and brain impairment in old age and increased risk of dementia, while the ε2 allele has been claimed to be neuroprotective. According to the 'antagonistic pleiotropy' hypothesis, these polymorphisms have different effects across the lifespan, with ε4, for example, postulated to confer benefits on cognitive and brain functions earlier in life. In this stage 2 of the Registered Report - https://osf.io/bufc4, we report the results from the cognitive and brain measures in the Cambridge Centre for Ageing and Neuroscience cohort (www.cam-can.org). We investigated the antagonistic pleiotropy hypothesis by testing for allele-by-age interactions in approximately 600 people across the adult lifespan (18-88 years), on six outcome variables related to cognition, brain structure and brain function (namely, fluid intelligence, verbal memory, hippocampal grey-matter volume, mean diffusion within white matter and resting-state connectivity measured by both functional magnetic resonance imaging and magnetoencephalography). We found no evidence to support the antagonistic pleiotropy hypothesis. Indeed, Bayes factors supported the null hypothesis in all cases, except for the (linear) interaction between age and possession of the ε4 allele on fluid intelligence, for which the evidence for faster decline in older ages was ambiguous. Overall, these pre-registered analyses question the antagonistic pleiotropy of APOE polymorphisms, at least in healthy adults
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