625 research outputs found
The heliospheric current sheet at solar maximum
Whilst near solar minimum it was possible to gain an understanding of the structure of the heliosphere in three dimensions using only low latitude in situ measurements, at solar maximum this was not the case. The Ulysses mission, with its unique almost polar orbit has provided an opportunity to investigate the structure of the heliosphere in three dimensions during a period of solar maximum. This thesis has focussed on investigating the topology and evolution of the HCS at solar maximum as well as the local structure of the boundary itself using magnetic field and plasma observations taken during the second Ulysses orbit. As a passive structure the Heliospheric Current Sheet (HCS) acts as a marker for the dynamic evolution of solar wind surrounding it while the large scale structure of the HCS also reflects the structure of the solar magnetic field. By combining simultaneous spacecraft observations at differing latitudes with potential field models the HCS was found to be near vertical at low latitudes and non planar at high latitudes. A second technique using minimum variance analysis to infer the orientation of the HCS concurred that the HCS extended to high latitudes, with the added suggestion that the topology was modified by stream interactions. Suprathermal electron heat flux measurements suggested the presence of substantial local HCS structure, especially during periods where the Ulysses trajectory skimmed along the HCS.Open acces
Synthesis, electrochemical and electrocatalytic properties of transition metal complexes based on cyclohexane-supported bis-imino pyridines
This thesis concerns the design and synthesis of transition metal complexes based on cyclohexane-supported bis-imino pyridines for use as electrocatalysts for hydrogen evolution, towards the aim of renewable energy storage.
To investigate the effect of secondary coordination interactions on electrochemistry and electrocatalytic response to protons, a series of transition metal complexes with the same fundamental bis-imino pyridine chelating groups, but with different ligand backbones of cyclohexane and cyclohexanol were synthesised. Two isomers of the cyclohexanol ligands were synthesised giving the hydroxyl groups positioned either distal or proximal to the metal centre, due to the conformational lock that occurs on metal coordination.
Coordination of these ligands to metal salts of Zn, Mn, Co, Ni and Cu gives a range of geometries. Ligands with no hydroxyl group (10, L1) or a distal (trans) hydroxyl (5, L2) both give octahedral geometries, whereas a proximal (cis) alcohol (9, L3) gives trigonal prismatic geometry for Zn, Mn and Co, but square-pyramidal geometry for Cu.
All of the complexes synthesised were shown to give rich electrochemistry, largely due to the redox non-innocent bis-imino pyridine ligands. The presence or absence and position of the hydroxyl group are shown to have a large effect on the cyclic voltammetry. This includes evidence for molecular motion involving the interconversion between different geometries: specifically trigonal prismatic and octahedral or square-based pyramidal.
Electrocatalysis is focused on the series of cobalt complexes as these were shown to give the largest response to acetic acid. Catalytic parameters, η, and TOFmax, of the cobalt complexes follow a trend in increasing η and TOFmax from the propane backbone, to cyclohexane backbone, to the distal cyclohexanol, to the proximal cyclohexanol. However bulk electrolysis of CoL3N with acetic acid indicates that proton reduction to hydrogen is not the primary electrocatalytic process for this complex, and suggests reduction of solvent. Future studies must address the nature of this process, and unambiguously establish those of the other complexes
Reduced dimensionality spin-orbit dynamics of CH3 + HCl reversible arrow CH4 Cl on ab initio surfaces
A reduced dimensionality quantum scattering method is extended to the study of spin-orbit nonadiabatic transitions in the CH3 + HCl reversible arrow CH4 + Cl(P-2(J)) reaction. Three two-dimensional potential energy surfaces are developed by fitting a 29 parameter double-Morse function to CCSD(T)/IB//MP2/cc-pV(T+d)Z-dk ab initio data; interaction between surfaces is described by geometry-dependent spin-orbit coupling functions fit to MCSCF/cc-pV(T+d)Z-dk ab initio data. Spectator modes are treated adiabatically via inclusion of curvilinear projected frequencies. The total scattering wave function is expanded in a vibronic basis set and close-coupled equations are solved via R-matrix propagation. Ground state thermal rate constants for forward and reverse reactions agree well with experiment. Multi-surface reaction probabilities, integral cross sections, and initial-state selected branching ratios all highlight the importance of vibrational energy in mediating nonadiabatic transition. Electronically excited state dynamics are seen to play a small but significant role as consistent with experimental conclusions. (C) 2011 American Institute of Physics. [doi:10.1063/1.3592732
Reliability of gastrointestinal barrier integrity and microbial translocation biomarkers at rest and following exertional heat stress
Purpose:Exertional heat stress adversely distrupts (GI) barrier integrity and, through subsequent microbial translocation (MT), negativly impacts health. Despite widespread application, the temporal reliability of popular GI barrier integity and MT biomarkers is poorly characterised.
Method: Fourteen males completed two 80âmin exertional heat stress tests (EHST) separated by 7â14 days. Venous blood was drawn pre, immediatelyâ and 1âhr post both EHSTs. GI barrier integrity was assessed using the serum DualâSugar Absorption Test (DSAT), Intestinal FattyâAcidâBinding Protein (IâFABP) and Claudinâ3 (CLDNâ3). MT was assessed using plasma Lipopolysaccharide Binding Protein (LBP), total 16S bacterial DNA and Bacteroides DNA.
Results: No GI barrier integrity or MT biomarker, except absolute Bacteroides DNA, displayed systematic trial order bias (p â„ .05). IâFABP (trial 1 = Î 0.834 ± 0.445 ng mlâ1; trial 2 = Î 0.776 ± 0.489 ng mlâ1) and CLDNâ3 (trial 1 = Î 0.317 ± 0.586 ng mlâ1; trial 2 = Î 0.371 ± 0.508 ng mlâ1) were increased postâEHST (p †.01). All MT biomarkers were unchanged postâEHST. Coefficient of variation and typical error of measurement postâEHST were: 11.5% and 0.004 (ratio) for the DSAT 90âmin postprobe ingestion; 12.2% and 0.004 (ratio) at 150âmin postprobe ingestion; 12.1% and 0.376 ng mlâ1 for IâFABP; 4.9% and 0.342 ng mlâ1 for CLDNâ3; 9.2% and 0.420 ”g mlâ1 for LBP; 9.5% and 0.15 pg ”lâ1 for total 16S DNA; and 54.7% and 0.032 for Bacteroides/total 16S DNA ratio.
Conclusion: Each GI barrier integrity and MT translocation biomarker, except Bacteroides/total 16S ratio, had acceptable reliability at rest and postexertional heat stress
The Health Halo Trend in UK Television Food Advertising Viewed by Children: The Rise of Implicit and Explicit Health Messaging in the Promotion of Unhealthy Foods
Monitoring the creative content within food marketing to children is strongly advocated by public health authorities, but few studies address the prevalence of health-related messaging in television adverts. Food and beverage adverts (n = 18,888 in 2008, n = 6664 in 2010) from UK television channels popular with children were coded and analyzed. Physical-activity depiction displayed an 18.8 percentage point increase from 2008 (4.4%) to 2010 (23.2%). Of the food adverts containing physical-activity depiction in 2010, 81.1% were for non-core foods. The appearance of health claims in food adverts in 2010 increased 4.1 percentage points from 2008 levels (20.7% to 24.8%) where the majority of food adverts featuring health and nutrition claims were for non-core foods (58.3%). Health-related (e.g., health/nutrition, weight loss/diet) appeals were used in 17.1% of food adverts during peak child-viewing times, rising to 33.0% of adverts shown on dedicated childrenâs channels in 2010. Implicit (physical activity) and explicit (health claims) health messages are increasingly prevalent in UK television food advertising viewed by children, and are frequently used to promote unhealthy foods. Policy makers in the UK should consider amendments to the existing statutory approach in order to address this issue
Foreign direct investment and investment environment in Dongguan Municipality of southern China
Based on 26 case studies, this paper investigates the socio-economic causes of the inflow of FDI and its policy implications in Dongguan. The favourable factors for foreign investors in Dongguan can be categorised under the Dunning's OLI (ownership, locational and internalisation advantages) framework. This paper argues that factors other than policy incentive, such as sub-contractual and pseudo integration, are playing more important roles in attracting the inflow of FDI and maintaining the high level of economic growth in Dongguan. This finding questions the effectiveness of policy incentives, such as tax-breaks, implemented by the Government as a means to attract FDI in Dongguan. The existence of 'Chinese crony capitalism' calls for further improvement in the implementation of laws and regulations in Dongguan and the reduction of bureaucratic red-tape by the central and local governments
Development of a new health-related quality of life measure for people with diabetes who experience hypoglycaemia:the Hypo-RESOLVE QoL
Aims/hypothesis: Valid and reliable patient-reported outcome measures are vital for assessing disease impact, responsiveness to healthcare and the cost-effectiveness of interventions. A recent review has questioned the ability of existing measures to assess hypoglycaemia-related impacts on health-related quality of life for people with diabetes. This mixed-methods project was designed to produce a novel health-related quality of life patient-reported outcome measure in hypoglycaemia: the Hypo-RESOLVE QoL.Methods: Three studies were conducted with people with diabetes who experience hypoglycaemia. In Stage 1, a comprehensive health-related quality of life framework for hypoglycaemia was elicited from semi-structured interviews (N=31). In Stage 2, the content validity and acceptability of draft measure content were tested via three waves of cognitive debriefing interviews (N=70 people with diabetes; N=14 clinicians). In Stage 3, revised measure content was administered alongside existing generic and diabetes-related measures in a large cross-sectional observational survey to assess psychometric performance (N=1246). The final measure was developed using multiple evidence sources, incorporating stakeholder engagement.Results: A novel conceptual model of hypoglycaemia-related health-related quality of life was generated, featuring 19 themes, organised by physical, social and psychological aspects. From a draft version of 76 items, a final 14-item measure was produced with satisfactory structural (Ï2=472.27, df=74, p<0.001; comparative fit index =0.943; root mean square error of approximation =0.069) and convergent validity with related constructs (r=0.46â0.59), internal consistency (α=0.91) and testâretest reliability (intraclass correlation coefficient =0.87).Conclusions/interpretation: The Hypo-RESOLVE QoL is a rigorously developed patient-reported outcome measure assessing the health-related quality of life impacts of hypoglycaemia. The Hypo-RESOLVE QoL has demonstrable validity and reliability and has value for use in clinical decision-making and as a clinical trial endpoint
Development of a new health-related quality of life measure for people with diabetes who experience hypoglycaemia:the Hypo-RESOLVE QoL
Aims/hypothesis: Valid and reliable patient-reported outcome measures are vital for assessing disease impact, responsiveness to healthcare and the cost-effectiveness of interventions. A recent review has questioned the ability of existing measures to assess hypoglycaemia-related impacts on health-related quality of life for people with diabetes. This mixed-methods project was designed to produce a novel health-related quality of life patient-reported outcome measure in hypoglycaemia: the Hypo-RESOLVE QoL.Methods: Three studies were conducted with people with diabetes who experience hypoglycaemia. In Stage 1, a comprehensive health-related quality of life framework for hypoglycaemia was elicited from semi-structured interviews (N=31). In Stage 2, the content validity and acceptability of draft measure content were tested via three waves of cognitive debriefing interviews (N=70 people with diabetes; N=14 clinicians). In Stage 3, revised measure content was administered alongside existing generic and diabetes-related measures in a large cross-sectional observational survey to assess psychometric performance (N=1246). The final measure was developed using multiple evidence sources, incorporating stakeholder engagement.Results: A novel conceptual model of hypoglycaemia-related health-related quality of life was generated, featuring 19 themes, organised by physical, social and psychological aspects. From a draft version of 76 items, a final 14-item measure was produced with satisfactory structural (Ï2=472.27, df=74, p<0.001; comparative fit index =0.943; root mean square error of approximation =0.069) and convergent validity with related constructs (r=0.46â0.59), internal consistency (α=0.91) and testâretest reliability (intraclass correlation coefficient =0.87).Conclusions/interpretation: The Hypo-RESOLVE QoL is a rigorously developed patient-reported outcome measure assessing the health-related quality of life impacts of hypoglycaemia. The Hypo-RESOLVE QoL has demonstrable validity and reliability and has value for use in clinical decision-making and as a clinical trial endpoint
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