Evidence for separatrix formation and sustainment with steady inductive helicity injection.

The first sustainment of toroidal plasma current of 50 kA at up to 3 times the injected currents, added in quadrature, using steady inductive helicity injection is described. Separatrix currents-currents not linking the helicity injectors-are sustained up to 40 kA. Decreases in the n=1 toroidal mode of the poloidal magnetic field at higher current amplifications indicate more quiescent, direct toroidal current drive. Results are achieved in HIT-SI (with a spheromak of major radius 0.3 m) during deuterium operations immediately after helium operation. These results represent a breakthrough in the development of this new current drive method for magnetic confinement fusion.

Convective and diffusive energetic particle losses induced by shear Alfvén waves in the ASDEX upgrade tokamak.

We present here the first phase-space characterization of convective and diffusive energetic particle losses induced by shear Alfvén waves in a magnetically confined fusion plasma. While single toroidal Alfvén eigenmodes (TAE) and Alfvén cascades (AC) eject resonant fast ions in a convective process, an overlapping of AC and TAE spatial structures leads to a large fast-ion diffusion and loss. Diffusive fast-ion losses have been observed with a single TAE above a certain threshold in the fluctuation amplitude.

Bispectrum analysis of electroencephalogram signals during waking and sleeping.

The degree of interaction of component waves making up a single electroencephalogram trace was strongly correlated with alpha activity, lead placement, and state of consciousness. Significant quadratic coupling of the waves was found only for awake subjects with high alpha activity. For these subjects about 50 percent of beta activity can be attributed to harmonic coupling with the alpha peak. During sleep, the degree of interaction was of borderline significance and did not follow a consistent pattern with respect to subject, frequency, state, or lead.

Noble gases confirm plume-related mantle degassing beneath Southern Africa.

Southern Africa is characterised by unusually elevated topography and abnormal heat flow. This can be explained by thermal perturbation of the mantle, but the origin of this is unclear. Geophysics has not detected a thermal anomaly in the upper mantle and there is no geochemical evidence of an asthenosphere mantle contribution to the Cenozoic volcanic record of the region. Here we show that natural CO2 seeps along the Ntlakwe-Bongwan fault within KwaZulu-Natal, South Africa, have C-He isotope systematics that support an origin from degassing mantle melts. Neon isotopes indicate that the melts originate from a deep mantle source that is similar to the mantle plume beneath Réunion, rather than the convecting upper mantle or sub-continental lithosphere. This confirms the existence of the Quathlamba mantle plume and importantly provides the first evidence in support of upwelling deep mantle beneath Southern Africa, helping to explain the regions elevation and abnormal heat flow.

Oxygen dynamics in shelf seas sediments incorporating seasonal variability.

Shelf sediments play a vital role in global biogeochemical cycling and are particularly important areas of oxygen consumption and carbon mineralisation. Total benthic oxygen uptake, the sum of diffusive and faunal mediated uptake, is a robust proxy to quantify carbon mineralisation. However, oxygen uptake rates are dynamic, due to the diagenetic processes within the sediment, and can be spatially and temporally variable. Four benthic sites in the Celtic Sea, encompassing gradients of cohesive to permeable sediments, were sampled over four cruises to capture seasonal and spatial changes in oxygen dynamics. Total oxygen uptake (TOU) rates were measured through a suite of incubation experiments and oxygen microelectrode profiles were taken across all four benthic sites to provide the oxygen penetration depth and diffusive oxygen uptake (DOU) rates. The difference between TOU and DOU allowed for quantification of the fauna mediated oxygen uptake and diffusive uptake. High resolution measurements showed clear seasonal and spatial trends, with higher oxygen uptake rates measured in cohesive sediments compared to the permeable sediment. The significant differences in oxygen dynamics between the sediment types were consistent between seasons, with increasing oxygen consumption during and after the phytoplankton bloom. Carbon mineralisation in shelf sediments is strongly influenced by sediment type and seasonality.

Benthic pH gradients across a range of shelf sea sediment types linked to sediment characteristics and seasonal variability.

This study used microelectrodes to record pH profiles in fresh shelf sea sediment cores collected across a range of different sediment types within the Celtic Sea. Spatial and temporal variability was captured during repeated measurements in 2014 and 2015. Concurrently recorded oxygen microelectrode profiles and other sedimentary parameters provide a detailed context for interpretation of the pH data. Clear differences in profiles were observed between sediment type, location and season. Notably, very steep pH gradients exist within the surface sediments (10-20 mm), where decreases greater than 0.5 pH units were observed. Steep gradients were particularly apparent in fine cohesive sediments, less so in permeable sandier matrices. We hypothesise that the gradients are likely caused by aerobic organic matter respiration close to the sediment-water interface or oxidation of reduced species at the base of the oxic zone (NH4 +, Mn2+, Fe2+, S-). Statistical analysis suggests the variability in the depth of the pH minima is controlled spatially by the oxygen penetration depth, and seasonally by the input and remineralisation of deposited organic phytodetritus. Below the pH minima the observed pH remained consistently low to maximum electrode penetration (ca. 60 mm), indicating an absence of sub-oxic processes generating H+ or balanced removal processes within this layer. Thus, a climatology of sediment surface porewater pH is provided against which to examine biogeochemical processes. This enhances our understanding of benthic pH processes, particularly in the context of human impacts, seabed integrity, and future climate changes, providing vital information for modelling benthic response under future climate scenarios.

Comparing benthic biogeochemistry at a sandy and a muddy site in the Celtic Sea using a model and observations.

Results from a 1D setup of the European Regional Seas Ecosystem Model (ERSEM) biogeochemical model were compared with new observations collected under the UK Shelf Seas Biogeochemistry (SSB) programme to assess model performance and clarify elements of shelf-sea benthic biogeochemistry and carbon cycling. Observations from two contrasting sites (muddy and sandy) in the Celtic Sea in otherwise comparable hydrographic conditions were considered, with the focus on the benthic system. A standard model parameterisation with site-specific light and nutrient adjustments was used, along with modifications to the within-seabed diffusivity to accommodate the modelling of permeable (sandy) sediments. Differences between modelled and observed quantities of organic carbon in the bed were interpreted to suggest that a large part (>90%) of the observed benthic organic carbon is biologically relatively inactive. Evidence on the rate at which this inactive fraction is produced will constitute important information to quantify offshore carbon sequestration. Total oxygen uptake and oxic layer depths were within the range of the measured values. Modelled depth average pore water concentrations of ammonium, phosphate and silicate were typically 5-20% of observed values at the muddy site due to an underestimate of concentrations associated with the deeper sediment layers. Model agreement for these nutrients was better at the sandy site, which had lower pore water concentrations, especially deeper in the sediment. Comparison of pore water nitrate with observations had added uncertainty, as the results from process studies at the sites indicated the dominance of the anammox pathway for nitrogen removal; a pathway that is not included in the model. Macrofaunal biomasses were overestimated, although a model run with increased macrofaunal background mortality rates decreased macrofaunal biomass and improved agreement with observations. The decrease in macrofaunal biomass was compensated by an increase in meiofaunal biomass such that total oxygen demand remained within the observed range. The permeable sediment modification reproduced some of the observed behaviour of oxygen penetration depth at the sandy site. It is suggested that future development in ERSEM benthic modelling should focus on: (1) mixing and degradation rates of benthic organic matter, (2) validation of benthic faunal biomass against large scale spatial datasets, (3) incorporation of anammox in the benthic nitrogen cycle, and (4) further developments to represent permeable sediment processes.

An approach for the identification of exemplar sites for scaling up targeted field observations of benthic biogeochemistry in heterogeneous environments.

Continental shelf sediments are globally important for biogeochemical activity. Quantification of shelf-scale stocks and fluxes of carbon and nutrients requires the extrapolation of observations made at limited points in space and time. The procedure for selecting exemplar sites to form the basis of this up-scaling is discussed in relation to a UK-funded research programme investigating biogeochemistry in shelf seas. A three-step selection process is proposed in which (1) a target area representative of UK shelf sediment heterogeneity is selected, (2) the target area is assessed for spatial heterogeneity in sediment and habitat type, bed and water column structure and hydrodynamic forcing, and (3) study sites are selected within this target area encompassing the range of spatial heterogeneity required to address key scientific questions regarding shelf scale biogeochemistry, and minimise confounding variables. This led to the selection of four sites within the Celtic Sea that are significantly different in terms of their sediment, bed structure, and macrofaunal, meiofaunal and microbial community structures and diversity, but have minimal variations in water depth, tidal and wave magnitudes and directions, temperature and salinity. They form the basis of a research cruise programme of observation, sampling and experimentation encompassing the spring bloom cycle. Typical variation in key biogeochemical, sediment, biological and hydrodynamic parameters over a pre to post bloom period are presented, with a discussion of anthropogenic influences in the region. This methodology ensures the best likelihood of site-specific work being useful for up-scaling activities, increasing our understanding of benthic biogeochemistry at the UK-shelf scale.

Rating the quality of evidence for clinical practice guidelines.

This article describes the system for rating the quality of medical evidence developed and used during creation of the Agency for Health Care Policy and Research-sponsored heart failure guideline. Previous approaches to rating evidence were not designed for use in the setting of clinical practice guidelines. The present system is based on the tenet that flaws in research design are serious to the extent they threaten the validity of the results of studies. A taxonomy of major and minor flaws based on that tenet was developed for randomized controlled trials and for cohort and medical registry studies. The use of the system is described in the context of two difficult clinical issues considered by the Panel: the role of coronary artery revascularization and the use of metoprolol.

Coronary event and case fatality rates in an English population: results of the Oxford myocardial infarction incidence study. The Oxford Myocardial Infarction Incidence Study Group.

OBJECTIVES: To determine coronary event and case fatality rates in an English population aged less than 80 years in Oxfordshire, and to compare these rates with those reported by the UK monitoring trends and determinants of cardiovascular disease (MONICA) centres in Scotland and Northern Ireland and those ascertained in Oxfordshire in 1966-67. DESIGN: A population wide surveillance study conducted in 1994-95 using prospective and retrospective case ascertainment. SETTING: A resident population in Oxfordshire of 568,800. SUBJECTS: Patients with suspected myocardial infarction or coronary death. OUTCOME MEASURES: A diagnosis of definite or possible myocardial infarction or coronary death using WHO MONICA diagnostic criteria based on symptoms, electrocardiograms, cardiac enzymes, necropsy findings, and past medical history. RESULTS: The annual rate for a first or recurrent coronary event per 100,000 population aged less than 65 years in 1994-95 was 273 for men and 66 for women after age adjustment to a standard world population. Rates in the age group 65-79 years were 1350 for men and 677 for women. Between 1966-67 and 1994-95, the age standardised event rate in the age group 30-69 years decreased significantly by 33% (95% confidence interval (CI) 44 to 21) in men, and there was a non-significant reduction of 8% (95% CI -33 to 17) in women. The age standardised 28 day case fatality rates also decreased significantly by 28% (95% CI 41 to 15) in men and by 32% (95% CI 55 to 9) in women. CONCLUSIONS: The coronary event rate in Oxfordshire was much lower than rates reported by MONICA centres in Glasgow and Belfast, and similar to rates reported by MONICA centres in France and northern Italy. The substantially lower event rate accounts for lower coronary heart disease mortality in Oxfordshire than in Scotland and Northern Ireland. The reduced coronary mortality in this region is attributable to declines in coronary event and case fatality rates.

Carriage and community treatment of methicillin-resistant Staphylococcus aureus: what happens to colonized patients after discharge?

During a maternity hospital outbreak of colonization/infection due to methicillin-resistant Staphylococcus aureus (MRSA), mothers and babies from 35 families were known to have been discharged colonized with MRSA. Thirty-two of these families were followed up by screening in the community. After 4 weeks, carriage was still detectable in 22 families. The ten families in which carriage was no longer detectable had MRSA isolated at discharge from enrichment culture only. All of the 11 families who had MRSA isolated on direct culture at discharge continued to carry MRSA. Mothers and babies from the 22 families still carrying MRSA at 4 weeks were offered topical treatment. Carriage persisted in ten of these families despite treatment. The most common site of persistent carriage was the perineum in mothers and the throat in infants.

N.m.r. studies of the flexibility of the glycosyl ring in thymidine and uridine nucleosides.

1H-N.m.r. spectroscopy at various temperatures has been used to investigate the flexibility of the glycosyl ring and to calculate the percentage of N- and S-character in the most favoured conformations in solution adopted by various pyrimidine deoxyribonucleosides. The position and orientation of substituents have a definite and predictable influence on the conformation of the deoxyribose ring in these nucleosides. The deoxyribose rings in the nucleosides studied were, in general, flexible except for those of 3'-deoxy-3'-fluoro- and 3'-azido-3'-deoxy-thymidine and 2'-deoxy-2'-fluoro-5-methyl-arabinosyluracil.

Hospitalization for ambulatory care-sensitive conditions: a method for comparative access and quality studies using routinely collected statistics.

BACKGROUND: Appropriate and timely provision of ambulatory care is an important factor in maintaining population health and in avoiding unneccessary hospital use. This article describes conditions for which hospitalization rates have a strong and inverse relationship to access to high-quality ambulatory care. METHODS: Three panels of Canadian physicians following different consensus techniques selected conditions for which the relative risk of hospitalization is inversely related to ambulatory care access. PRINCIPAL FINDINGS: All panels identified asthma, angina pectoris, congestive heart failure, otitis media, gastric ulcer, pelvic inflammatory disease, malignant hypertension, and immunization-preventable infections as ambulatory care-sensitive admissions. These conditions strongly overlap with lists developed for similar purposes in the U.S. and England. INTERPRETATION: Ambulatory care-sensitive conditions represent an intermediate health outcome. They are distinct from inappropriate hospitalizations. They may be useful for measuring the impact of health care policy, and for performance measurement or audit.

Assessing quality of care: what are the implications of the potential lack of sensitivity of outcome measures to differences in quality?

Measuring outcome can be an insensitive way to detect differences in the quality of health care. This paper captures the implications of this poor sensitivity for the interpretation of studies of outcome that compare provider performance, and considers in what circumstances monitoring outcome might be useful. When interpreting studies, it is important to consider the size of the effect that a difference in the quality of care might be expected to have on outcome and whether it is likely that important differences in quality might not have been detected. It is argued that outcome measures may be of value when how you do something is as important as what you do, when process measures are invalid or impractical, and when the overall effectiveness of an intervention is critically dependent upon its complication rate.

Health of workers exposed to 1, 1, 1,-trichloroethane: a matched-pair study.

An epidemiologic study of 151 matched pairs of employees was conducted in two adjacent textile plants, one of which used inhibited 1,1,1-trichloroethane as a general cleaning solvent. Employees in the study population had exposures to the solvent for 6 yrs or less at varying concentrations which were measured by breathing zone sampling and personal monitoring. While cardiovascular and hepatic observations were of primary interest, other health parameters were also studied. Application of sensitive statistical techniques and careful examination of all data did not reveal any clinically pertinent findings that were associated with exposure to 1,1,1-trichloroethane. The statistically significant associations that were observed between health measures and nonexposure factors emphasize the need to consider age, sex, race, and other variables in designing epidemiologic studies.

Some observations on attempts to measure appropriateness of care.

There are a growing number of published studies that suggest that much health care is delivered inappropriately. There are calls for measures of appropriateness to be used by purchasers and others to regulate or influence the delivery of health care. This paper explores assumptions inherent in results generated by a leading measure of appropriateness and concludes that there are considerable uncertainties about the measure's meaning, the magnitude of bias that it contains, and the degree to which its application can be generalised. Some of these uncertainties could be resolved if the tacit assumptions inherent in the generation of the criteria could be made explicit. Existing measures of appropriateness are not yet sufficiently robust to be used with confidence to influence or control the delivery of health care. They may have a use as an aid rather than as a constraint in clinical decision making. A randomised controlled trial could resolve whether patients achieve better outcomes if their care is influenced by appropriateness criteria.

Detecting differences in quality of care: the sensitivity of measures of process and outcome in treating acute myocardial infarction.

The merits or otherwise of publishing hospital specific death rates are much debated. This article compares the relative sensitivity of measures of process and outcome to differences in quality of care for the hospital treatment of myocardial infarction. Aspects of hospital care that have a proved impact on mortality from myocardial infarction are identified, and the results from meta-analysis and large randomised controlled trials are used to estimate the impact that optimal use of these interventions would have on mortality in a typical district general hospital. Sample size calculations are then performed to determine how many years of data would be needed to detect significant differences between hospitals. A comparison is then made with the amount of data that would be needed to detect significant differences if information about process of care was being collected. Process measures based on the results of randomised controlled trials were found to be able to detect relevant differences between hospitals that would not be identified by comparing hospital specific mortality, which is an insensitive indicator of the quality of care.

General practitioners' opinions of health services available to their patients.

OBJECTIVES: To establish a means for general practitioners to express their views about health services available to their patients, to identify services that general practitioners perceive as most in need of improvement, and to establish good working relations between the health authority's purchasing team and local general practitioners. DESIGN: Postal questionnaire survey of general practitioners. SETTING: Bristol and Weston health district. SUBJECTS: 226 general practitioners, of whom 171 replied. MAIN OUTCOME MEASURES: Scores of quality and quantity of hospital and community services, frequency that services were identified as priorities for improvement, and the nature of written comments received about services. RESULTS: There was considerable agreement among respondents about which services were adequate and which were inadequate. Most services were perceived as at least adequate in both quality and quantity, but seven services were perceived by more than 60% (102) of doctors as inadequate or worse in quantity and eight by 10% (17) of doctors as poor in quality. Orthopaedics, ophthalmology, care of elderly people, and physiotherapy were the services doctors most wanted improved. CONCLUSIONS: A postal questionnaire is an acceptable and accurate method of obtaining general practitioners' views about services available to their patients. General practitioners' priorities differ from those obtained from hospital medical advisory mechanisms.