An analytical model employing both large displacement and Timoshenko beam theories is presented for tubes with circular cross-sections under pure bending. The resulting equations are solved numerically to simulate the inhomogeneous buckling deformation and the moment–curvature relationships for various tubes constructed from orthotropic materials. Not only is this an advancement on classical Brazier buckling theory, but a significant modal interaction is identified that severely reduces the moment capacity of tubes with particular levels of the shear modulus.
Abstract By combining new NRAO 12m data with previously published BIMA data, we have obtained very high signal-to-noise maps of HCO + in the Orion B core, which contain information on both the large- and small-scale emission and put new constraints on the gas’ physical conditions.
<h3>Rationale</h3> Chronic obstructive pulmonary disease (COPD) is an irreversible inflammatory lung disease and is currently the fourth greatest burden of disease of worldwide. However a key issue is that patients show a lack of response to corticosteroid treatment. Corticosteroid insensitivity is mainly caused by oxidative stress which directly stimulates inflammatory transcription factors and reduces the activity of co-adaptor proteins essential for the inhibitory actions of corticosteroids. AMP-activated kinase (AMPK) is a serine/threonine protein kinase that regulates cellular energy homeostasis and anti-oxidant defences, and has recently been labelled as an anti-ageing molecule. We hypothesised that activation of AMPK using Quercetin reverses corticosteroid resistance caused by cigarette smoke extract (CSE) in a monocytic cell line. <h3>Methods</h3> Human monocytic cell line, U937s, were initially incubated with Quercetin (20µM) for 24 hours and then exposed to CSE for 2 hours. Cells were then treated with dexamethasone (1x10<sup>-11</sup> to 1x10<sup>-6</sup>M) for 45 minutes and stimulated with TNF-a (10ng/ml) for 24 hours. Supernatants were collected and CXCL-8 was measured using ELISA. Corticosteroid resistance was calculated as the ability of dexamethasone to inhibit 25% of TNF-a-induced CXCL-8 (IC<sub>25</sub>). Activation of AMPK by Quercetin was measured using the levels of the phosphorylated AMPK by Western Blot. Nuclear factor erythroid related factor 2 (Nrf-2) levels and glucocorticoid receptor (GR) nuclear translocation were also assessed using Western Blot. <h3>Results</h3> CSE induced corticosteroid resistance in U937s (IC<sub>25</sub> = 30nM vs IC<sub>25</sub> = 5nM). Interestingly Quercetin restored corticosteroid sensitivity by approximately 3 fold (IC<sub>25</sub> = 11nM) compared to CSE. Quercetin increased levels of activated AMPK and also up-regulated the expression of Nrf-2. However, Quercetin was unable to restore GR nuclear translocation. <h3>Conclusions</h3> Quercetin was found to be a potential novel therapy for restoration of corticosteroid sensitivity in COPD. Although the mechanism of action remains to be elucidated, Nrf-2 and AMPK activations which increase anti-oxidant levels and prevents oxidative damage could be a key the mechanism of action Activation of AMPK could therefore be a potential novel mechanism for the restoration of corticosteroid sensitivity and Quercetin could be used as an add-on treatment to corticosteroids in COPD.
<p>The effect of geometric nonlinearities in the response of under-deck cable-stayed bridges with steel−concrete composite decks is studied. Influence lines for deflections and bending moments at different sections of the deck are obtained, and these are found to be different to those for conventional bridges. Nonlinearities affect principally the response of lateral subspans, in which both deflections and bending moments are amplified. The permanent state should be studied by taking nonlinearities into account. Deflections under further loads can be obtained with linear models. Geometric nonlinear effects increase design bending moments under ultimate loads by 12% when compared with linear models. Some additional design criteria for designers aiming to design under-deck cable-stayed bridges are hence provided.</p>
The purpose of this study is to summarize cumulative evidence suggesting that the combination of fractional flow reserve (FFR), coronary flow reserve (CFR) and the index of microcirculatory resistance (IMR) might provide a more comprehensive invasive assessment of ischaemic heart disease (IHD).Myocardial flow impairment in IHD results from both obstructive and nonobstructive causes. However, its diagnosis is primarily stenosis-centred. Although FFR provides valuable information on obstructive disease, its theoretical framework largely neglects the importance of nonobstructive concomitant involvement. Substantial evidence suggests, however, that nonobstructive IHD has important prognostic implications, and CFR and IMR are readily available tools for its concomitant diagnosis. Furthermore, CFR and IMR have independently been shown to improve IHD risk stratification. Further studies should address whether this more comprehensive IHD diagnosis, derived from the combination of FFR, CFR and IMR, may improve prognostic risk stratification and guide therapeutic strategies aiming for both obstructive and nonobstructive IHD involvement.FFR, CFR and IMR have independently been shown to improve IHD risk stratification. Their combined use is feasible and appealing, and might lead to a more comprehensive invasive assessment of IHD.