3,301 research outputs found

    Dielectric and thermal relaxation in the energy landscape

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    We derive an energy landscape interpretation of dielectric relaxation times in undercooled liquids, comparing it to the traditional Debye and Gemant-DiMarzio-Bishop pictures. The interaction between different local structural rearrangements in the energy landscape explains qualitatively the recently observed splitting of the flow process into an initial and a final stage. The initial mechanical relaxation stage is attributed to hopping processes, the final thermal or structural relaxation stage to the decay of the local double-well potentials. The energy landscape concept provides an explanation for the equality of thermal and dielectric relaxation times. The equality itself is once more demonstrated on the basis of literature data for salol.Comment: 7 pages, 3 figures, 41 references, Workshop Disordered Systems, Molveno 2006, submitted to Philosophical Magazin

    Substitutions of red meat, poultry and fish and risk of myocardial infarction

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    AbstractRed meat has been suggested to be adversely associated with risk of myocardial infarction (MI), but previous studies have rarely taken replacement foods into consideration. We aimed to investigate optimal substitutions between and within the food groups of red meat, poultry and fish for MI prevention. We followed up 55 171 women and men aged 50–64 years with no known history of MI at recruitment. Diet was assessed by a validated 192-item FFQ at baseline. Adjusted Cox proportional hazard models were used to calculate hazard ratios (HR) and 95 % CI for specified food substitutions of 150 g/week. During a median follow-up time of 13·6 years, we identified 656 female and 1694 male cases. Among women, the HR for replacing red meat with fatty fish was 0·76 (95 % CI 0·64, 0·89), whereas the HR for replacing red meat with lean fish was 1·00 (95 % CI 0·89, 1·14). Similarly, replacing poultry with fatty but not lean fish was inversely associated with MI: the HR was 0·81 (95 % CI 0·67, 0·98) for fatty fish and was 1·08 (95 % CI 0·92, 1·27) for lean fish. The HR for replacing lean with fatty fish was 0·75 (95 % CI 0·60, 0·94). Replacing processed with unprocessed red meat was not associated with MI. Among men, a similar pattern was found, although the associations were not statistically significant. This study suggests that replacing red meat, poultry or lean fish with fatty fish is associated with a lower risk of MI.</jats:p

    Substitution of meat and fish with vegetables or potatoes and risk of myocardial infarction

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    AbstractRed meat has been suggested to be adversely associated with risk of myocardial infarction (MI), whereas vegetable consumption has been found to be protective. The aim of this study was to investigate substitutions of red meat, poultry and fish with vegetables or potatoes for MI prevention. We followed up 29 142 women and 26 029 men in the Danish Diet, Cancer and Health study aged 50–64 years with no known history of MI at baseline. Diet was assessed by a validated 192-item FFQ at baseline. Adjusted Cox proportional hazard models were used to calculate hazard ratios (HR) and 95 % CI for MI associated with specified food substitutions of 150 g/week. During a median follow-up of 13·6 years, we identified 656 female and 1694 male cases. Among women, the HR for MI when replacing red meat with vegetables was 0·94 (95 % CI 0·90, 0·98). Replacing fatty fish with vegetables was associated with a higher risk of MI (HR 1·23; 95 % CI 1·05, 1·45), whereas an inverse, statistically non-significant association was found for lean fish (HR 0·93; 95 % CI 0·83, 1·05). Substituting poultry with vegetables was not associated with risk of MI (HR 1·00; 95 % CI 0·90, 1·11). Findings for substitution with potatoes were similar to findings for vegetables. Among men, a similar pattern was observed, but the associations were weak and mostly statistically non-significant. This study suggests that replacing red meat with vegetables or potatoes is associated with a lower risk of MI, whereas replacing fatty fish with vegetables or potatoes is associated with a higher risk of MI.</jats:p

    Primary and malignant cholangiocytes undergo CD40 mediated Fas dependent Apoptosis, but are insensitive to direct activation with exogenous fas ligand

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    Introduction Cholangiocarcinoma is a rare malignancy of the biliary tract, the incidence of which is rising, but the pathogenesis of which remains uncertain. No common genetic defects have been described but it is accepted that chronic inflammation is an important contributing factor. We have shown that primary human cholangiocyte and hepatocyte survival is tightly regulated via co-operative interactions between two tumour necrosis family (TNF) receptor family members; CD40 and Fas (CD95). Functional deficiency of CD154, the ligand for CD40, leads to a failure of clearance of biliary tract infections and a predisposition to cholangiocarcinoma implying a direct link between TNF receptor-mediated apoptosis and the development of cholangiocarcinoma. Aims To determine whether malignant cholangiocytes display defects in CD40 mediated apoptosis. By comparing CD40 and Fas-mediated apoptosis and intracellular signalling in primary human cholangiocytes and three cholangiocyte cell lines. Results Primary cholangiocytes and cholangiocyte cell lines were relatively insensitive to direct Fas-mediated killing with exogenous FasL when compared with Jurkat cells, which readily underwent Fas-mediated apoptosis, but were extremely sensitive to CD154 stimulation. The sensitivity of cells to CD40 activation was similar in magnitude in both primary and malignant cells and was STAT-3 and AP-1 dependent in both. Conclusions 1) Both primary and malignant cholangiocytes are relatively resistant to Fas–mediated killing but show exquisite sensitivity to CD154, suggesting that the CD40 pathway is intact and fully functional in both primary and malignant cholangiocytes 2) The relative insensitivity of cholangiocytes to Fas activation demonstrates the importance of CD40 augmentation of Fas dependent death in these cells. Agonistic therapies which target CD40 and associated intracellular signalling pathways may be effective in promoting apoptosis of malignant cholangiocytes
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