453 research outputs found

    Recent Developments of Electrochemical Wall Mass Transfer Probes and Their Application to Drag-Reducing Polymers

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    Electrochemical mass transfer probes are used to measure the velocity gradient at a wall. Recent advances in their application are reviewed. These include corrections for the time response of the probe, the simultaneous measurement at a number of locations of the two components of the fluctuating velocity gradient and a study of the influence of drag reducing polymers on turbulence. It is found that drag-reducing polymers cause an increase in the scale of flow oriented eddies in the viscous sublayer

    Turbulent Dispersion of Heavy Particles With Nonlinear Drag

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    Comparison of Characteristics and Complications in Men Versus Women Undergoing Chronic Total Occlusion Percutaneous Intervention

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    Gender differences exist in clinical outcomes after routine percutaneous coronary intervention (PCI), but studies reporting such outcomes after chronic total occlusion (CTO) PCI are limited. We assessed the characteristics and outcomes of female patients undergoing CTO PCI. We retrospectively analyzed a dedicated national (United Kingdom) prospective CTO database from 2011 to 2015 for outcomes and characteristics of female patients undergoing CTO PCI (unmatched and propensity matched). Female patients constituted 20.5% (n = 260 of 1,271) of the unmatched cohort and 33.3% (n = 233 of 699) of the matched cohort and were more likely to be older (women aged >70 years, 48% in the unmatched and 45% in the matched cohort). An increased inhospital complication rate was observed in female patients (unmatched: 10% women vs 4.45% men, p = 0.0012, and matched 9.87% women vs 3.86% men, p = 0.0032). Coronary perforation, bleeding, and contrast-induced nephropathy were more frequently observed in female patients. Femoral access site with >6 French sheath was associated with an increased risk of bleeding. Presence of calcification in the CTO artery was associated with coronary perforation (grade III) in female patients in the matched cohort (p = 0.007). Female patients undergoing CTO PCI were older and experienced increased of inhospital complications. Increased awareness of these complications could influence the selection of access site and sheath size, the need for prehydration, judicious choice of balloon size, collateral selection, and wire placement in female patients undergoing CTO PCI

    Frailty among older adults and its distribution in England

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    Background: Information on the spatial distribution of the frail population is crucial to inform service planning in health and social care. Objectives: To estimate small-area frailty prevalence among older adults using survey data. To assess whether prevalence differs between urban, rural, coastal and inland areas of England. Design: Using data from the English Longitudinal Study of Ageing (ELSA), ordinal logistic regression was used to predict the probability of frailty, according to age, sex and area deprivation. Probabilities were applied to demographic and economic information in 2020 population projections to estimate the district-level prevalence of frailty. Results: The prevalence of frailty in adults aged 50+ (2020) in England was estimated to be 8.1 [95% CI 7.3–8.8]%. We found substantial geographic variation, with the prevalence of frailty varying by a factor of 4.0 [3.5–4.4] between the most and least frail areas. A higher prevalence of frailty was found for urban than rural areas, and coastal than inland areas. There are widespread geographic inequalities in healthy ageing in England, with older people in urban and coastal areas disproportionately frail relative to those in rural and inland areas. Conclusions: Interventions aimed at reducing inequalities in healthy ageing should be targeted at urban and coastal areas, where the greatest benefit may be achieved

    The effect on endothelial function of vitamin C during methionine induced hyperhomocysteinaemia

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    BACKGROUND: Manipulation of total homocysteine concentration with oral methionine is associated with impairment of endothelial-dependent vasodilation. This may be caused by increased oxidative stress. Vitamin C is an aqueous phase antioxidant vitamin and free radical scavenger. We hypothesised that if the impairment of endothelial function related to experimental hyperhomocysteinaemia was free radically mediated then co-administration of vitamin C should prevent this. METHODS: Ten healthy adults took part in this crossover study. Endothelial function was determined by measuring forearm blood flow (FBF) in response to intra-arterial infusion of acetylcholine (endothelial-dependent) and sodium nitroprusside (endothelial-independent). Subjects received methionine (100 mg/Kg) plus placebo tablets, methionine plus vitamin C (2 g orally) or placebo drink plus placebo tablets. Study drugs were administered at 9 am on each study date, a minimum of two weeks passed between each study. Homocysteine (tHcy) concentration was determined at baseline and after 4 hours. Endothelial function was determined at 4 hours. Responses to the vasoactive substances are expressed as the area under the curve of change in FBF from baseline. Data are mean plus 95% Confidence Intervals. RESULTS: Following oral methionine tHcy concentration increased significantly versus placebo. At this time endothelial-dependent responses were significantly reduced compared to placebo (31.2 units [22.1-40.3] vs. 46.4 units [42.0-50.8], p < 0.05 vs. Placebo). Endothelial-independent responses were unchanged. Co-administration of vitamin C did not alter the increase in homocysteine or prevent the impairment of endothelial-dependent responses (31.4 [19.5-43.3] vs. 46.4 units [42.0-50.8], p < 0.05 vs. Placebo) CONCLUSIONS: This study demonstrates that methionine increased tHcy with impairment of the endothelial-dependent vasomotor responses. Administration of vitamin C did not prevent this impairment and our results do not support the hypothesis that the endothelial impairment is mediated by adverse oxidative stress

    Symptoms and quality of life in late stage Parkinson syndromes: a longitudinal community study of predictive factors

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    BACKGROUND Palliative care is increasingly offered earlier in the cancer trajectory but rarely in Idiopathic Parkinson's Disease(IPD), Progressive Supranuclear Palsy(PSP) or Multiple System Atrophy(MSA). There is little longitudinal data of people with late stage disease to understand levels of need. We aimed to determine how symptoms and quality of life of these patients change over time; and what demographic and clinical factors predicted changes. METHODS We recruited 82 patients into a longitudinal study, consenting patients with a diagnosis of IPD, MSA or PSP, stages 3-5 Hoehn and Yahr(H&Y). At baseline and then on up to 3 occasions over one year, we collected self-reported demographic, clinical, symptom, palliative and quality of life data, using Parkinson's specific and generic validated scales, including the Palliative care Outcome Scale (POS). We tested for predictors using multivariable analysis, adjusting for confounders. FINDINGS Over two thirds of patients had severe disability, over one third being wheelchair-bound/bedridden. Symptoms were highly prevalent in all conditions - mean (SD) of 10.6(4.0) symptoms. More than 50% of the MSA and PSP patients died over the year. Over the year, half of the patients showed either an upward (worsening, 24/60) or fluctuant (8/60) trajectory for POS and symptoms. The strongest predictors of higher levels of symptoms at the end of follow-up were initial scores on POS (AOR 1.30; 95%CI:1.05-1.60) and being male (AOR 5.18; 95% CI 1.17 to 22.92), both were more predictive than initial H&Y scores. INTERPRETATION The findings point to profound and complex mix of non-motor and motor symptoms in patients with late stage IPD, MSA and PSP. Symptoms are not resolved and half of the patients deteriorate. Palliative problems are predictive of future symptoms, suggesting that an early palliative assessment might help screen for those in need of earlier intervention

    Multiplicity dependence of jet-like two-particle correlations in p-Pb collisions at sNN\sqrt{s_{NN}} = 5.02 TeV

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    Two-particle angular correlations between unidentified charged trigger and associated particles are measured by the ALICE detector in p-Pb collisions at a nucleon-nucleon centre-of-mass energy of 5.02 TeV. The transverse-momentum range 0.7 <pT,assoc<pT,trig< < p_{\rm{T}, assoc} < p_{\rm{T}, trig} < 5.0 GeV/cc is examined, to include correlations induced by jets originating from low momen\-tum-transfer scatterings (minijets). The correlations expressed as associated yield per trigger particle are obtained in the pseudorapidity range η<0.9|\eta|<0.9. The near-side long-range pseudorapidity correlations observed in high-multiplicity p-Pb collisions are subtracted from both near-side short-range and away-side correlations in order to remove the non-jet-like components. The yields in the jet-like peaks are found to be invariant with event multiplicity with the exception of events with low multiplicity. This invariance is consistent with the particles being produced via the incoherent fragmentation of multiple parton--parton scatterings, while the yield related to the previously observed ridge structures is not jet-related. The number of uncorrelated sources of particle production is found to increase linearly with multiplicity, suggesting no saturation of the number of multi-parton interactions even in the highest multiplicity p-Pb collisions. Further, the number scales in the intermediate multiplicity region with the number of binary nucleon-nucleon collisions estimated with a Glauber Monte-Carlo simulation.Comment: 23 pages, 6 captioned figures, 1 table, authors from page 17, published version, figures at http://aliceinfo.cern.ch/ArtSubmission/node/161

    Charge separation relative to the reaction plane in Pb-Pb collisions at sNN=2.76\sqrt{s_{\rm NN}}= 2.76 TeV

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    Measurements of charge dependent azimuthal correlations with the ALICE detector at the LHC are reported for Pb-Pb collisions at sNN=2.76\sqrt{s_{\rm NN}} = 2.76 TeV. Two- and three-particle charge-dependent azimuthal correlations in the pseudo-rapidity range η<0.8|\eta| < 0.8 are presented as a function of the collision centrality, particle separation in pseudo-rapidity, and transverse momentum. A clear signal compatible with a charge-dependent separation relative to the reaction plane is observed, which shows little or no collision energy dependence when compared to measurements at RHIC energies. This provides a new insight for understanding the nature of the charge dependent azimuthal correlations observed at RHIC and LHC energies.Comment: 12 pages, 3 captioned figures, authors from page 2 to 6, published version, figures at http://aliceinfo.cern.ch/ArtSubmission/node/286
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