Optimal configuration problem identification of electrical power cable in tidal turbine farm via traveling salesman problem modeling approach

Electrical power cables in tidal turbine farms contribute a significant share to capital expenditure (CAPEX). As a result, the routing of electrical power cables connecting turbines to cable collector hubs must be designed so as to obtain the least cost configuration. This is referred to as a tidal cable routing problem. This problem possesses several variants depending on the number of cable collector hubs. In this paper, these variants are modeled by employing the approach of the single depot multiple traveling salesman problem (mTSP) and the multiple depot mTSP of operational research for the single and multiple cable collector variants, respectively. The developed optimization models are computationally implemented using MATLAB. In the triple cable collector cable hub variant, an optimal solution is obtained, while good-quality suboptimal solutions are obtained in the double and single cable collector hub variants. In practice, multiple cable collector hubs are expected to be employed as the multiple hub configurations tend to be more economic than the single hub configurations. This has been confirmed by this paper for an optimal tidal turbine layout obtained with OpenTidalFarm. Suggestions are presented for future research studies comprising a number of heuristics.info:eu-repo/semantics/publishedVersio

Regional myocardial function after intracoronary bone marrow cell injection in reperfused anterior wall infarction - a cardiovascular magnetic resonance tagging study

<p>Abstract</p> <p>Background</p> <p>Trials have brought diverse results of bone marrow stem cell treatment in necrotic myocardium. This substudy from the Autologous Stem Cell Transplantation in Acute Myocardial Infarction trial (ASTAMI) explored global and regional myocardial function after intracoronary injection of autologous mononuclear bone marrow cells (mBMC) in acute anterior wall myocardial infarction treated with percutaneous coronary intervention.</p> <p>Methods</p> <p>Cardiovascular magnetic resonance (CMR) tagging was performed 2-3 weeks and 6 months after revascularization in 15 patients treated with intracoronary stem cell injection (mBMC group) and in 13 controls without sham injection. Global and regional left ventricular (LV) strain and LV twist were correlated to cine CMR and late gadolinium enhancement (LGE).</p> <p>Results</p> <p>In the control group myocardial function as measured by strain improved for the global LV (6 months: -13.1 ± 2.4 versus 2-3 weeks: -11.9 ± 3.4%, p = 0.014) and for the infarct zone (-11.8 ± 3.0 versus -9.3 ± 4.1%, p = 0.001), and significantly more than in the mBMC group (inter-group p = 0.027 for global strain, respectively p = 0.009 for infarct zone strain). LV infarct mass decreased (35.7 ± 20.4 versus 45.7 ± 29.5 g, p = 0.024), also significantly more pronounced than the mBMC group (inter-group p = 0.034). LV twist was initially low and remained unchanged irrespective of therapy.</p> <p>Conclusions</p> <p>LGE and strain findings quite similarly demonstrate subtle differences between the mBMC and control groups. Intracoronary injection of autologous mBMC did not strengthen regional or global myocardial function in this substudy.</p> <p>Trial registration</p> <p>ClinicalTrials.gov: <a href="http://www.clinicaltrials.gov/ct2/show/NCT00199823">NCT00199823</a></p

Longitudinal peak strain detects a smaller risk area than visual assessment of wall motion in acute myocardial infarction

<p>Abstract</p> <p>Background</p> <p>Opening of an occluded infarct related artery reduces infarct size and improves survival in acute ST-elevation myocardial infarction (STEMI). In this study we performed tissue Doppler analysis (peak strain, displacement, mitral annular movement (MAM)) and compared with visual assessment for the study of the correlation of measurements of global, regional and segmental function with final infarct size and transmurality. In addition, myocardial risk area was determined and a prediction sought for the development of infarct transmurality ≥50%.</p> <p>Methods</p> <p>Twenty six patients with STEMI submitted for primary percutaneous coronary intervention (PCI) were examined with echocardiography on the catheterization table. Four to eight weeks later repeat echocardiography was performed for reassessment of function and magnetic resonance imaging for the determination of final infarct size and transmurality.</p> <p>Results</p> <p>On a global level, wall motion score index (WMSI), ejection fraction (EF), strain, and displacement all showed significant differences (p ≤ 0.001, p ≤ 0.001, p ≤ 0.001 and p = 0.03) between the two study visits, but MAM did not (p = 0.17). On all levels (global, regional and segmental) and both pre- and post PCI, WMSI showed a higher correlation with scar transmurality compared to strain. We found that both strain and WMSI predicted the development of scar transmurality ≥50%, but strain added no significant information to that obtained with WMSI in a logistic regression analysis.</p> <p>Conclusions</p> <p>In patients with acute STEMI, WMSI, EF, strain, and displacement showed significant changes between the pre- and post PCI exam. In a ROC-analysis, strain had 64% sensitivity at 80% specificity and WMSI around 90% sensitivity at 80% specificity for the detection of scar with transmurality ≥50% at follow-up.</p

Non-uniform recovery of left ventricular transmural mechanics in ST-segment elevation myocardial infarction

<p>Abstract</p> <p>Background</p> <p>After a transient ischemic episode, the subendocardial region is more severely injured than outer subepicardial layers and may regain a proportionately greater degree of mechanical function in the longitudinal direction. We sought to explore left ventricular (LV) transmural mechanics in patients with ST-segment elevation myocardial infarction (STEMI) for determining the mechanism underlying recovery of global LV function after primary percutaneous coronary intervention (PCI).</p> <p>Methods</p> <p>A total of 42 patients (62 ± 11 years old, 71% male) with a first STEMI underwent serial assessments of LV longitudinal, circumferential and radial strains (LS, CS and RS) by selective tracking of subendocardial and subepicardial regions within 48 hours and a median of 5 months after PCI. LV mechanical parameters were compared with sixteen age and gender matched normal controls.</p> <p>Results</p> <p>In comparison with controls, endocardial and epicardial LS were markedly attenuated at 48 hours following PCI (P < 0.001). An improvement in LV ejection fraction (EF > 5%) following PCI was seen in 24 (57%) patients and was associated with improvement in endocardial and epicardial LS (P < 0.001 and P = 0.003, respectively) and endocardial CS (P = 0.01). Radial strain and wall motion score index, however, remained persistently abnormal. The change in endocardial LS (OR 1.2, 95% CI 1.03 to 1.42, P = 0.01) and the change in epicardial LS (OR 1.2, 95% 1.03 to 1.46, P = 0.02) were significantly associated with the improvement in LVEF, independent of the location of STEMI and the presence of underlying multivessel disease.</p> <p>Conclusions</p> <p>In patients with STEMI treated by PCI, the recovery of LV subendocardial shortening strain seen in the longitudinal direction underlies the improvement in LV global function despite persistent abnormalities in radial mechanics and wall motion score index.</p

The role of left ventricular deformation in the assessment of microvascular obstruction and intramyocardial haemorrhage

In the setting of acute ST-elevation myocardial infarction (STEMI), it remains unclear which strain parameter most strongly correlates with microvascular obstruction (MVO) or intramyocardial haemorrhage (IMH). We aimed to investigate the association of MVO, IMH and convalescent left ventricular (LV) remodelling with strain parameters measured with cardiovascular magnetic resonance (CMR). Forty-three patients with reperfused STEMI and 10 age and gender matched healthy controls underwent CMR within 3-days and at 3-months following reperfused STEMI. Cine, T2-weighted, T2*-imaging and late gadolinium enhancement (LGE) imaging were performed. Infarct size, MVO and IMH were quantified. Peak global longitudinal strain (GLS), global radial strain (GRS), global circumferential strain (GCS) and their strain rates were derived by feature tracking analysis of LV short-axis, 4-chamber and 2-chamber cines. All 43 patients and ten controls completed the baseline scan and 34 patients completed 3-month scans. In multivariate regression, GLS demonstrated the strongest association with MVO or IMH (beta = 0.53, p 20%). Baseline GLS also demonstrated the strongest diagnostic performance in predicting adverse LV remodelling (AUC = 0.79; 95% CI 0.60–0.98; p = 0.03). Post-reperfused STEMI, baseline GLS was most closely associated with the presence of MVO or IMH. Baseline GLS was more strongly associated with adverse LV remodelling than other CMR parameters

How organic farmers view their own practice: results from the Czech Republic

This paper addresses the development of organic agriculture in the Czech Republic, which is seen as a success story among post-communist countries. The relatively short history of organic farming and specific contextual factors raises questions about the nature and meaning of Czech organic farming. The goal of this study was to find out how farmers view their own practice, interpret its symbolic value, and construct its content. This empirical study uses Q methodology aimed at the identification of the collectively-shared perspectives belonging engaged actors. Data were gathered through semi-standardized interviews with Czech farmers registered in official organic scheme. The analysis emphasized three components, which are considered as three distinct perspectives possessed by organic farmers; that is, (1) organic farming as a way of life, (2) as an occupation, and (3) as a production of food of an alternative quality compared to conventional food. Each viewpoint entails a different understanding of what organic farming means; each then—when considered together—comprises the meaning of organic agriculture in the Czech Republic. The presented classification of the farmers holding the viewpoints contributes to the ongoing theoretical discussion regarding the nature of the current organic sector, its development and potential conventionalization