91 research outputs found
Numerical investigations on the transient aerodynamic performance characterization of a multibladed vertical axis wind turbine.
The use of vertical axis wind turbines (VAWTs) in urban environments is on the rise due to their relatively smaller size, simpler design, lower manufacturing and maintenance costs, and above all, due to their omnidirectionality. The multibladed drag-based VAWT has been identified as a design configuration with superior aerodynamic performance. Numerous studies have been carried out in order to better understand the complex aerodynamic performance of multibladed VAWTs employing steady-state or quasi-steady numerical methods. The transient aerodynamics associated with a multibladed VAWT, especially the timeâhistory of the power coefficient of each blade, has not been reported in the published literature. This information is important for the identification of individual bladeâs orientation when producing negative torque. The current study aims to bridge this gap in the literature through real-time tracking of the rotor blade's aerodynamic performance characteristics during one complete revolution. Numerical investigations were carried out using advanced computational fluid dynamics (CFD)-based techniques for a tip speed ratio of 0 to 1. The results indicate that transient aerodynamic characterization is 13% more accurate in predicting the power generation from the VAWT. While steady-state performance characterization indicates a negative power coefficient (Cp) at λ = 0.65, transient analysis suggests that this happens at λ = 0.75
Diagnostic accuracy of 3.0-T magnetic resonance T1 and T2 mapping and T2-weighted dark-blood imaging for the infarct-related coronary artery in Non-ST-segment elevation myocardial infarction
Background: Patients with recent nonâSTâsegment elevation myocardial infarction commonly have heterogeneous characteristics that may be challenging to assess clinically.
Methods and Results: We prospectively studied the diagnostic accuracy of 2 novel (T1, T2 mapping) and 1 established (T2âweighted short tau inversion recovery [T2WâSTIR]) magnetic resonance imaging methods for imaging the ischemic area at risk and myocardial salvage in 73 patients with nonâSTâsegment elevation myocardial infarction (mean age 57±10 years, 78% male) at 3.0âT magnetic resonance imaging within 6.5±3.5 days of invasive management. The infarctârelated territory was identified independently using a combination of angiographic, ECG, and clinical findings. The presence and extent of infarction was assessed with late gadolinium enhancement imaging (gadobutrol, 0.1 mmol/kg). The extent of acutely injured myocardium was independently assessed with native T1, T2, and T2WâSTIR methods. The mean infarct size was 5.9±8.0% of left ventricular mass. The infarct zone T1 and T2 times were 1323±68 and 57±5 ms, respectively. The diagnostic accuracies of T1 and T2 mapping for identification of the infarctârelated artery were similar (P=0.125), and both were superior to T2WâSTIR (P<0.001). The extent of myocardial injury (percentage of left ventricular volume) estimated with T1 (15.8±10.6%) and T2 maps (16.0±11.8%) was similar (P=0.838) and moderately well correlated (r=0.82, P<0.001). Mean extent of acute injury estimated with T2WâSTIR (7.8±11.6%) was lower than that estimated with T1 (P<0.001) or T2 maps (P<0.001).
Conclusions: In patients with nonâSTâsegment elevation myocardial infarction, T1 and T2 magnetic resonance imaging mapping have higher diagnostic performance than T2WâSTIR for identifying the infarctârelated artery. Compared with conventional STIR, T1 and T2 maps have superior value to inform diagnosis and revascularization planning in nonâSTâsegment elevation myocardial infarction.
Clinical Trial Registration: URL: http://www.clinicaltrials.gov. Unique identifier: NCT02073422
Practices of strength and conditioning coaches: a snapshot from different sports, countries and expertise levels
This study describes the practices of strength and conditioning coaches (SCCs) from different sports, countries and expertise levels. One-hundred and fifty-six SCCs (31.9 + 8.9 years old) completed an online survey, consisting of 40 questions (36 fixed response and 4 open-ended), with eight sections: (a) background information, (b) muscular strength and power development, (c) speed development, (d) plyometrics, (e) flexibility development, (f) physical testing, (g) technology use, and (h) programming and any additional comments. Responses were received from 48 sports and 17 countries. This study provides exploratory evidence incorporating responses primarily in soccer (45%), track and field (30%), volleyball (23%), golf (17%) and tennis (17%). A Bachelorâs degree or higher were held by 99% of SCCs, of which 94% were in a sports science related field, and 71% held a strength and conditioning related certification or accreditation. Periodization strategies and physical testing were used by 94% of SCCs. The hang clean (82%), power clean (76%), and clean high pull (63%) were the most commonly prescribed Olympic Weightlifting exercises. Multiple hops/lunges (84%) were the most commonly prescribed plyometrics exercises. For open ended questions, 40% of SCCs wanted to integrate more technology into their programs, whereas, 30% of coaches believed technology will be the main future trend in strength and conditioning. SCCs from different sports, countries and expertise levels can use the information presented in this study to review their current practices and potentially provide a source of new ideas for diversifying or modifying future practices too
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Advanced Oxyfuel Boilers and Process Heaters for Cost Effective CO2 Capture and Sequestration
The purpose of the advanced boilers and process heaters program is to assess the feasibility of integrating Oxygen Transport Membranes (OTM) into combustion processes for cost effective CO{sub 2} capture and sequestration. Introducing CO{sub 2} capture into traditional combustion processes can be expensive, and the pursuit of alternative methods, like the advanced boiler/process heater system, may yield a simple and cost effective solution. In order to assess the integration of an advanced boiler/process heater process, this program addressed the following tasks: Task 1--Conceptual Design; Task 2--Laboratory Scale Evaluation; Task 3--OTM Development; Task 4--Economic Evaluation and Commercialization Planning; and Task 5--Program Management. This Final report documents and summarizes all of the work performed for the DOE award DE-FC26-01NT41147 during the period from January 2002-March 2007. This report outlines accomplishments for the following tasks: conceptual design and economic analysis, oxygen transport membrane (OTM) development, laboratory scale evaluations, and program management
Coronary Heart Disease and Ischemic Stroke Polygenic Risk Scores and atherosclerotic Cardiovascular Disease in a Diverse, Population-Based Cohort Study
The predictive ability of coronary heart disease (CHD) and ischemic stroke (IS) polygenic risk scores (PRS) have been evaluated individually, but whether they predict the combined outcome of atherosclerotic cardiovascular disease (ASCVD) remains insufficiently researched. It is also unclear whether associations of the CHD and IS PRS with ASCVD are independent of subclinical atherosclerosis measures. 7,286 White and 2,016 Black participants from the population-based Atherosclerosis Risk in Communities study who were free of cardiovascular disease and type 2 diabetes at baseline were included. We computed previously validated CHD and IS PRS consisting of 1,745,179 and 3,225,583 genetic variants, respectively. Cox proportional hazards models were used to test the association between each PRS and ASCVD, adjusting for traditional risk factors, ankle-brachial index, carotid intima media thickness, and carotid plaque. The hazard ratios (HR) for the CHD and IS PRS were significant with HR of 1.50 (95% CI: 1.36-1.66) and 1.31 (95% CI: 1.18-1.45) respectively for the risk of incident ASCVD per standard deviation increase in CHD and IS PRS among White participants after adjusting for traditional risk factors. The HR for the CHD PRS was not significant with an HR of 0.95 (95% CI: 0.79-1.13) for the risk of incident ASCVD in Black participants. The HR for the IS PRS was significant with an HR of 1.26 (95%CI: 1.05-1.51) for the risk of incident ASCVD in Black participants. The association of the CHD and IS PRS with ASCVD was not attenuated in White participants after adjustment for ankle-brachial index, carotid intima media thickness, and carotid plaque. The CHD and IS PRS do not cross-predict well, and predict better the outcome for which they were created than the composite ASCVD outcome. Thus, the use of the composite outcome of ASCVD may not be ideal for genetic risk prediction
Brain changes: aerobic exercise for traumatic brain injury rehabilitation
IntroductionTraumatic Brain Injury (TBI) accounts for millions of hospitalizations and deaths worldwide. Aerobic exercise is an easily implementable, non-pharmacological intervention to treat TBI, however, there are no clear guidelines for how to best implement aerobic exercise treatment for TBI survivors across age and injury severity.MethodsWe conducted a PRISMA-ScR to examine research on exercise interventions following TBI in children, youth and adults, spanning mild to severe TBI. Three electronic databases (PubMed, PsycInfo, and Web of Science) were searched systematically by two authors, using keywords delineated from âTraumatic Brain Injury,â âAerobic Exercise,â and âIntervention.âResultsOf the 415 papers originally identified from the search terms, 54 papers met the inclusion criteria and were included in this review. The papers were first grouped by participantsâ injury severity, and subdivided based on age at intervention, and time since injury where appropriate.DiscussionAerobic exercise is a promising intervention for adolescent and adult TBI survivors, regardless of injury severity. However, research examining the benefits of post-injury aerobic exercise for children and older adults is lacking
Coronary heart disease and ischemic stroke polygenic risk scores and atherosclerotic cardiovascular disease in a diverse, population-based cohort study
The predictive ability of coronary heart disease (CHD) and ischemic stroke (IS) polygenic risk scores (PRS) have been evaluated individually, but whether they predict the combined outcome of atherosclerotic cardiovascular disease (ASCVD) remains insufficiently researched. It is also unclear whether associations of the CHD and IS PRS with ASCVD are independent of subclinical atherosclerosis measures. 7,286 White and 2,016 Black participants from the population-based Atherosclerosis Risk in Communities study who were free of cardiovascular disease and type 2 diabetes at baseline were included. We computed previously validated CHD and IS PRS consisting of 1,745,179 and 3,225,583 genetic variants, respectively. Cox proportional hazards models were used to test the association between each PRS and ASCVD, adjusting for traditional risk factors, ankle-brachial index, carotid intima media thickness, and carotid plaque. The hazard ratios (HR) for the CHD and IS PRS were significant with HR of 1.50 (95% CI: 1.36â1.66) and 1.31 (95% CI: 1.18â1.45) respectively for the risk of incident ASCVD per standard deviation increase in CHD and IS PRS among White participants after adjusting for traditional risk factors. The HR for the CHD PRS was not significant with an HR of 0.95 (95% CI: 0.79â1.13) for the risk of incident ASCVD in Black participants. The HR for the IS PRS was significant with an HR of 1.26 (95%CI: 1.05â1.51) for the risk of incident ASCVD in Black participants. The association of the CHD and IS PRS with ASCVD was not attenuated in White participants after adjustment for ankle-brachial index, carotid intima media thickness, and carotid plaque. The CHD and IS PRS do not cross-predict well, and predict better the outcome for which they were created than the composite ASCVD outcome. Thus, the use of the composite outcome of ASCVD may not be ideal for genetic risk prediction
Repeatability of Corticospinal and Spinal Measures during Lengthening and Shortening Contractions in the Human Tibialis Anterior Muscle
Elements of the human central nervous system (CNS) constantly oscillate. In addition, there are also methodological factors and changes in muscle mechanics during dynamic muscle contractions that threaten the stability and consistency of transcranial magnetic stimulation (TMS) and perpherial nerve stimulation (PNS) measures
Training future generations to deliver evidence-based conservation and ecosystem management
1. To be effective, the next generation of conservation practitioners and managers need to be critical thinkers with a deep understanding of how to make evidence-based decisions and of the value of evidence synthesis. 2. If, as educators, we do not make these priorities a core part of what we teach, we are failing to prepare our students to make an effective contribution to conservation practice. 3. To help overcome this problem we have created open access online teaching materials in multiple languages that are stored in Applied Ecology Resources. So far, 117 educators from 23 countries have acknowledged the importance of this and are already teaching or about to teach skills in appraising or using evidence in conservation decision-making. This includes 145 undergraduate, postgraduate or professional development courses. 4. We call for wider teaching of the tools and skills that facilitate evidence-based conservation and also suggest that providing online teaching materials in multiple languages could be beneficial for improving global understanding of other subject areas.Peer reviewe
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