1,040 research outputs found

    Power requirements for electron cyclotron current drive and ion cyclotron resonance heating for sawtooth control in ITER

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    13MW of electron cyclotron current drive (ECCD) power deposited inside the q = 1 surface is likely to reduce the sawtooth period in ITER baseline scenario below the level empirically predicted to trigger neo-classical tearing modes (NTMs). However, since the ECCD control scheme is solely predicated upon changing the local magnetic shear, it is prudent to plan to use a complementary scheme which directly decreases the potential energy of the kink mode in order to reduce the sawtooth period. In the event that the natural sawtooth period is longer than expected, due to enhanced alpha particle stabilisation for instance, this ancillary sawtooth control can be provided from > 10MW of ion cyclotron resonance heating (ICRH) power with a resonance just inside the q = 1 surface. Both ECCD and ICRH control schemes would benefit greatly from active feedback of the deposition with respect to the rational surface. If the q = 1 surface can be maintained closer to the magnetic axis, the efficacy of ECCD and ICRH schemes significantly increases, the negative effect on the fusion gain is reduced, and off-axis negative-ion neutral beam injection (NNBI) can also be considered for sawtooth control. Consequently, schemes to reduce the q = 1 radius are highly desirable, such as early heating to delay the current penetration and, of course, active sawtooth destabilisation to mediate small frequent sawteeth and retain a small q = 1 radius.Comment: 29 pages, 16 figure

    Effect of tanniniferous browse meal on nematode faecal egg counts and internal parasite burdens in sheep and goats

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    The effect of tanniniferous browse meal on faecal egg counts (FEC) and intestinal worm burdens was investigated in sheep and goats infested experimentally with gastrointestinal nematodes. Initially, leaves of different browse tree species were assayed for condensed tannin (CT) content using a colorimetric method to determine concentration and seasonal variations. The level of CT in the leaves ranged between 58 – 283 g/kg dry matter. Seasonal changes in CT levels were influenced by stage of leaf maturity with peak levels after the wet season in June. Leaves of Acacia polyacantha had the highest tannin concentration and were used to test their anthelmintic effect in goats and sheep infested with the nematodes in two separate feeding trials. In Trial 1 an acacia leaf meal supplement (AMS) was offered at 100 – 130 g/animal/day for 20 days to growing Small East African goats to investigate its effect on FEC and worm burden. Mean FEC and worm burden of the AMS-fed group were respectively 27% and 13% lower than in the control group. Trial 2 was similar to Trial 1 except that AMS was offered for 30 days to growing Black Head Persian sheep at 170 g/animal/day. The sheep receiving AMS showed a slight reduction in FEC (on average 19% lower than the control group) but had no effect on worm burden. The current results substantiated previous reports of a suppressing effect of CT on gastrointestinal nematodes of small ruminants. Although the observed anthelmintic activity of AMS was less than expected, such reductions can have practical epidemiological implications in reducing pasture larval contamination. Further studies are needed under field conditions to evaluate the feasibility of using locally available tanniniferous browse as an alternative to synthetic anthelmintics in reducing worm infestations in small ruminants. South African Journal of Animal Science Vol. 37 (2) 2007: pp. 97-10

    Epidemiology and healthcare factors associated with neonatal enterococcal infections

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    OBJECTIVE: To investigate the epidemiology and healthcare factors associated with late-onset neonatal enterococcal infections. DESIGN: Multicentre, multinational retrospective cohort study using prospectively collected infection data from a neonatal infection surveillance network between 2004 and 2016; this was supplemented with healthcare data from a questionnaire distributed to participating neonatal units. SETTING: Sixty neonatal units across Europe (UK, Greece, Estonia) and Australia. PATIENTS: Infants admitted to participating neonatal units who had a positive culture of blood, cerebrospinal fluid or urine after 48 hours of life. RESULTS: In total, 414 episodes of invasive Enterococcus spp infection were reported in 388 infants (10.1% of a total 4083 episodes in 3602 infants). Enterococcus spp were the second most common cause of late-onset infection after coagulase-negative Staphylococcus spp and were strongly associated with necrotising enterocolitis (NEC) (adjusted OR 1.44, 95% CI 1.02 to 2.03, p=0.038), total parenteral nutrition (TPN) (adjusted OR 1.34, 95% CI 1.06 to 1.70, p=0.016), increasing postnatal age (per 1-week increase: adjusted OR 1.04, 95% CI 1.02 to 1.06, p<0.001) and decreasing birth weight (per 1 kg increase: adjusted OR 0.85, 95% CI 0.74 to 0.97, p=0.017). There was no evidence that inadequate nurse to patient staffing ratios in high-dependency units were associated with a higher risk of enterococcal infections. CONCLUSIONS: Enterococcus spp were the second most frequent cause of late-onset infections. The association between enterococcal infections, NEC and TPN may inform empiric antimicrobial regimens in these contexts and provide insights into reducing these infections

    Patient symptoms and experience following COVID-19: results from a UK-wide survey

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    Objectives: To investigate the experience of people who continue to be unwell after acute COVID-19, often referred to as ‘long COVID’, both in terms of their symptoms and their interactions with healthcare. Design: We conducted a mixed-methods analysis of responses to a survey accessed through a UK online post-COVID support and information hub between April and December 2020 about people’s experiences after having acute COVID-19. Participants: 3290 respondents, 78% female 92.1% white ethnicity and median age range 45-54 years; 12.7% had been hospitalised. 494(16.5%) completed the survey between 4 and 8 weeks of the onset of their symptoms, 641(21.4%) between 8 and 12 weeks and 1865(62.1%) >12 weeks after. Results: The ongoing symptoms most frequently reported were; breathing problems (92.1%), fatigue (83.3%), muscle weakness or joint stiffness (50.6%), sleep disturbances (46.2%), problems with mental abilities (45.9%) changes in mood, including anxiety and depression (43.1%) and cough (42.3%). Symptoms did not appear to be related to the severity of the acute illness or to the presence of pre-existing medical conditions. Analysis of free text responses revealed three main themes (1) Experience of living with COVID-19 – physical and psychological symptoms that fluctuate unpredictably; (2) Interactions with healthcare that were unsatisfactory; (3) Implications for the future – their own condition, society and the healthcare system, and the need for research Conclusion: Consideration of patient perspective and experiences will assist in the planning of services to address problems persisting in people who remain symptomatic after the acute phase of COVID-19

    Prognostic significance of endogenous adhesion/growth-regulatory lectins in lung cancer

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    Objective: To determine the expression of endogenous adhesion/growth-regulatory lectins and their binding sites using labeled tissue lectins as well as the binding profile of hyaluronic acid as an approach to define new prognostic markers. Methods: Sections of paraffin-embedded histological material of 481 lungs from lung tumor patients following radical lung excision processed by a routine immunohistochemical method (avidin-biotin labeling, DAB chromogen). Specific antibodies against galectins-1 and - 3 and the heparin-binding lectin were tested. Staining by labeled galectins and hyaluronic acid was similarly visualized by a routine protocol. After semiquantitative assessment of staining, the results were compared with the pT and pN stages and the histological type. Survival was calculated by univariate and multivariate methods. Results: Binding of galectin-1 and its expression tended to increase, whereas the parameters for galectin-3 decreased in advanced pT and pN stages at a statistically significant level. The number of positive cases was considerably smaller among the cases with small cell lung cancer than in the group with non-small-cell lung cancer, among which adenocarcinomas figured prominently with the exception of galectin-1 expression. Kaplan-Meier computations revealed that the survival rate of patients with galectin-3-binding or galectin-1-expressing tumors was significantly poorer than that of the negative cases. In the multivariate calculations of survival lymph node metastases ( p < 0.0001), histological type ( p = 0.003), galectin-3-binding capacity ( p = 0.01), galectin-3 expression ( p = 0.03) and pT status ( p = 0.003) proved to be independent prognostic factors, not correlated with the pN stage. Conclusion: The expression and the capacity to bind the adhesion/growth regulatory galectin-3 is defined as an unfavorable prognostic factor not correlated with the pTN stage. Copyright (C) 2005 S. Karger AG, Basel

    Sensitivity to Error Fields in NSTX High Beta Plasmas

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    It was found that error field threshold decreases for high ÎČ in NSTX, although the density correlation in conventional threshold scaling implies the threshold would increase since higher ÎČ plasmas in our study have higher plasma density. This greater sensitivity to error field in higher ÎČ plasmas is due to error field amplification by plasmas. When the effect of amplification is included with ideal plasma response calculations, the conventional density correlation can be restored and threshold scaling becomes more consistent with low ÎČ plasmas. However, it was also found that the threshold can be significantly changed depending on plasma rotation. When plasma rotation was reduced by non-resonant magnetic braking, the further increase of sensitivity to error field was observed

    Aerodynamic investigations of ventilated brake discs.

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    The heat dissipation and performance of a ventilated brake disc strongly depends on the aerodynamic characteristics of the flow through the rotor passages. The aim of this investigation was to provide an improved understanding of ventilated brake rotor flow phenomena, with a view to improving heat dissipation, as well as providing a measurement data set for validation of computational fluid dynamics methods. The flow fields at the exit of four different brake rotor geometries, rotated in free air, were measured using a five-hole pressure probe and a hot-wire anemometry system. The principal measurements were taken using two-component hot-wire techniques and were used to determine mean and unsteady flow characteristics at the exit of the brake rotors. Using phase-locked data processing, it was possible to reveal the spatial and temporal flow variation within individual rotor passages. The effects of disc geometry and rotational speed on the mean flow, passage turbulence intensity, and mass flow were determined. The rotor exit jet and wake flow were clearly observed as characterized by the passage geometry as well as definite regions of high and low turbulence. The aerodynamic flow characteristics were found to be reasonably independent of rotational speed but highly dependent upon rotor geometry

    UKPMC: a full text article resource for the life sciences

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    UK PubMed Central (UKPMC) is a full-text article database that extends the functionality of the original PubMed Central (PMC) repository. The UKPMC project was launched as the first ‘mirror’ site to PMC, which in analogy to the International Nucleotide Sequence Database Collaboration, aims to provide international preservation of the open and free-access biomedical literature. UKPMC (http://ukpmc.ac.uk) has undergone considerable development since its inception in 2007 and now includes both a UKPMC and PubMed search, as well as access to other records such as Agricola, Patents and recent biomedical theses. UKPMC also differs from PubMed/PMC in that the full text and abstract information can be searched in an integrated manner from one input box. Furthermore, UKPMC contains ‘Cited By’ information as an alternative way to navigate the literature and has incorporated text-mining approaches to semantically enrich content and integrate it with related database resources. Finally, UKPMC also offers added-value services (UKPMC+) that enable grantees to deposit manuscripts, link papers to grants, publish online portfolios and view citation information on their papers. Here we describe UKPMC and clarify the relationship between PMC and UKPMC, providing historical context and future directions, 10 years on from when PMC was first launched
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