160 research outputs found
Geothermics Correct Energy Conservation in Geothermal Wellbore Simulation
Abstract A fundamental error of interpretation of static steam dryness versus flowing steam quality in the coding of the simulator GWELL has been found, that means it does not correctly conserve energy or momentum. GWELL, or the energy and momentum subroutines from it, may have formed a basis for other geothermal wellbore simulator codes in existence, prompting this note on how to quickly check if your favorite geothermal wellbore simulator is actually conserving energy. The possible consequences of using a simulator that does not conserve momentum or energy as presumed, are also briefly explored
Intravenous omega-3, a technique to prevent an excessive innate immune response to cardiac surgery in a rodent gut ischemia model
ObjectivesNeutrophil infiltration of tissues as part of the inflammatory response to cardiac surgery is one of the major mediators of postoperative multiple-organ dysfunction. Omega-3 fatty acids markedly attenuate endothelial cell inflammatory responses, including upregulation of neutrophil adhesion molecules. The efficacy of a clinically safe form of omega-3 to produce this effect in vivo was examined.MethodsRat gut intravital microscopic analysis was used to visualize neutrophil transmigration from the microcirculation into the tissues of the gut. Inflammatory activation was in the form of 30 minutes of ischemia and 90 minutes of reperfusion. Sham, control (0.9% saline infusion over 4 hours), and omega-3 (Omegaven [Fresenius Kabi, Bad Homburg, Germany] infusion over 4 hours) pretreatments were compared.ResultsIschemia–reperfusion resulted in a 4-fold increase in neutrophil adherence to the endothelium (baseline: 4.3 ± 0.2 vs control group: 19.2 ± 3.5 adherent neutrophils per 100 μm, P < .01), which intravenous omega-3 suppressed (7.8 ± 1.7 adherent neutrophils per 100 μm, P < .01). Omega-3 pretreatment also reduced neutrophil transmigration into the tissues after reperfusion (sham group: 6.3 ± 0.8 vs control group: 13.2 ± 1.4 vs omega-3 group: 9.4 ± 0.9 neutrophils per field, P = .037). Gut tissue levels of the neutrophil-released enzyme myeloperoxidase were similarly markedly reduced with omega-3 pretreatment (sham group: 10.5 ± 1.6 vs control group: 19.0 ± 3.3 vs omega-3 group: 10.1 ± 1.2 U/g, P = .03).ConclusionsFour hours' pretreatment with a relatively safe form of intravenous omega-3 suppressed neutrophil adherence and tissue infiltration, resulting in lower levels of the tissue-damaging enzyme myeloperoxidase. This suggests a possible strategy for diminishing postoperative multiple-organ dysfunction
Modelling the cardiovascular system for assessing the blood pressure curve
A four compartment model of the cardiovascular system is developed. To allow for easy interpretation and to minimise the number of parameters, an effort was made to keep the model as simple as possible. Using a standard method (Matlab function fminsearch) to calculate the parameter values led to unacceptable run times or non-convergence. Consequently we developed an algorithm which first finds the most important model parameters and uses these as a basis for a four stage process which accurately determines all parameter values. This process is then applied to data from three ICU patients. Good agreement between the model and measured arterial pressure is demonstrated in all cases
Stock Market Integration, Return Forecastability and Implications for Market Efficiency: A Panel Study
Endovascular Thrombectomy for Ischemic Stroke Increases Disability-Free Survival, Quality of Life, and Life Expectancy and Reduces Cost
Background: Endovascular thrombectomy improves functional outcome in large vessel occlusion ischemic stroke. We examined disability, quality of life, survival and acute care costs in the EXTEND-IA trial, which used CT-perfusion imaging selection. Methods: Large vessel ischemic stroke patients with favorable CT-perfusion were randomized to endovascular thrombectomy after alteplase versus alteplase-only. Clinical outcome was prospectively measured using 90-day modified Rankin scale (mRS). Individual patient expected survival and net difference in Disability/Quality-adjusted life years (DALY/QALY) up to 15 years from stroke were modeled using age, sex, 90-day mRS, and utility scores. Level of care within the first 90 days was prospectively measured and used to estimate procedure and inpatient care costs (US15,689 versus US10,515). The average saving per patient treated with thrombectomy was US$4,365. c Conclusion: Thrombectomy patients with large vessel occlusion and salvageable tissue on CT-perfusion had reduced length of stay and overall costs to 90 days. There was evidence of clinically relevant improvement in long-term survival and quality of life.Peer reviewe
Student Experiences of Multidisciplinarity in the Undergraduate Geography Curriculum
This paper explores the student experience of multidisciplinarity within the undergraduate Geography curriculum. It considers the drivers that have underpinned this development before considering the findings of research into student experiences in two universities in the south of England. The results suggest that most students view this development positively and recognize a number of advantages that it brings, citing expanded opportunities for learning, working with people from other disciplines, expansion of perspectives and perceived benefits to employability. However, for a minority this development is more problematic. The research points here to issues with specialist knowledge and disciplinary pedagogies, social issues within the classroom and class organization and some reservations regarding groupwork. The paper concludes with a series of recommendations
Putting Themselves in the Picture: Using Reflective Diaries in the Teaching of Feminist Geography
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