Advanced 3-D viscous SSME turbine rotor stator CFD algorithms

Current Space Shuttle Main Engine (SSME) high pressure fuel turbopump problems have generated a desire to analyze the flow field of rotating machinery. The status of Computational Fluid Dynamics (CFD) has reached the point that soon the capability to solve unsteady three-dimensional viscous flow fields will be at hand. The work presented involves upgrading the computational efficiency of an operational three-dimensional algorithm. The modifications include algorithm development, algorithm approximation and acceleration, and special coding optimizations. The overall result of these modifications has reduced processing time by nearly 80%

Measurements and analysis of cavitation in a pressure reducing valve during operation – a case study

This paper proposes a methodology and presents its practical application for evaluating whether a pressure reducing valve (PRV) is under cavitation during its operation in a water distribution system. The approach is based on collecting measurements over a 24-hour period such that high demand and low demand times are included. The ollected measurements allow evaluation of four indicators related to cavitation, namely the draulic cavitation index, noise generated by the valve, acoustic cavitation index and the spectra of the noise. These four indicators provide sufficient information for diagnosis of cavitation with high certainty

Improved 3-D turbomachinery CFD algorithm

The building blocks of a computer algorithm developed for the time-accurate flow analysis of rotating machines are described. The flow model is a finite volume method utilizing a high resolution approximate Riemann solver for interface flux definitions. This block LU implicit numerical scheme possesses apparent unconditional stability. Multi-block composite gridding is used to orderly partition the field into a specified arrangement. Block interfaces, including dynamic interfaces, are treated such as to mimic interior block communication. Special attention is given to the reduction of in-core memory requirements by placing the burden on secondary storage media. Broad applicability is implied, although the results presented are restricted to that of an even blade count configuration. Several other configurations are presently under investigation, the results of which will appear in subsequent publications

Utility-service provision as an example of a complex system

Utility–service provision is a process in which products are transformed by appropriate devices into services satisfying human needs and wants. Utility products required for these transformations are usually delivered to households via separate infrastructures, i.e., real-world networks such as, e.g., electricity grids and water distribution systems. owever, provision of utility products in appropriate quantities does not itself guarantee hat the required services will be delivered because the needs satisfaction task requires not only utility products but also fully functional devices. Utility infrastructures form complex networks and have been analyzed as such using complex network theory. However, little research has been conducted to date on integration of utilities and associated services within one complex network. This paper attempts to fill this gap in knowledge by modelling utility–service provision within a household with a hypergraph in which products and services are represented with nodes whilst devices are hyperedges spanning between them. Since devices usually connect more than two nodes, a standard graph would not suffice to describe utility–service provision problem and therefore a hypergraph was chosen as a more appropriate representation of the system. This paper first aims to investigate the properties of hypergraphs, such as cardinality of nodes, betweenness, degree distribution, etc. Additionally, it shows how these properties can be used while solving and optimizing utility– service provision problem, i.e., constructing a so-called transformation graph. The transformation graph is a standard graph in which nodes represent the devices, storages for products, and services, while edges represent the product or service carriers. Construction of different transformation graphs to a defined utility– service provision problem is presented in the paper to show how the methodology is applied to generate possible solutions to provision of services to households under given local conditions, requirements and constraints

Longitudinal Multimodal fMRI to Investigate Neurovascular Changes in Spontaneously Hypertensive Rats

Hypertension is an important risk factor for age‐related cognitive decline and neuronal pathologies. Studies have shown a correlation between hypertension, disruption in neurovascular coupling and cerebral autoregulation, and cognitive decline. However, the mechanisms behind this are unclear. To further understand this, it is advantageous to study neurovascular coupling as hypertension progresses in a rodent model. Here, we use a longitudinal functional MRI (fMRI) protocol to assess the impact of hypertension on neurovascular coupling in spontaneously hypertensive rats (SHRs). Eight female SHRs were studied at 2, 4, and 6 months of age, as hypertension progressed. Under an IV infusion of propofol, animals underwent fMRI, functional MR spectroscopy, and cerebral blood flow (CBF) quantification to study changes in neurovascular coupling over time. Blood pressure significantly increased at 4 and 6 months (P < .0001). CBF significantly increased at 4 months old (P < .05), in the acute stage of hypertension. The size of the active region decreased significantly at 6 months old (P < .05). Change in glutamate signal during activation, and N‐acetyl‐aspartate (NAA) signal, remained constant. This study shows that, while cerebral autoregulation is impaired in acute hypertension, the blood oxygenation‐level‐dependent (BOLD) response remains unaltered until later stages. At this stage, the consistent NAA and glutamate signals show that neuronal death has not occurred, and that neuronal activity is not affected at this stage. This suggests that neuronal activity and viability is not lost until much later, and changes observed here in BOLD activity are due to vascular effects

A longitudinal, multi-parametric functional MRI study to determine age-related changes in the rodent brain

As the population ages, the incidence of age-related neurological diseases and cognitive decline increases. To further understand disease-related changes in brain function it is advantageous to examine brain activity changes in healthy aging rodent models to permit mechanistic investigation. Here, we examine the suitability, in rodents, of using a novel, minimally invasive anaesthesia protocol in combination with a functional MRI protocol to assess alterations in neuronal activity due to physiological aging. 11 Wistar Han female rats were studied at 7, 9, 12, 15 and 18 months of age. Under an intravenous infusion of propofol, animals underwent functional magnetic resonance imaging (fMRI) and functional magnetic resonance spectroscopy (fMRS) with forepaw stimulation to quantify neurotransmitter activity, and resting cerebral blood flow (CBF) quantification using arterial spin labelling (ASL) to study changes in neurovascular coupling over time. Animals showed a significant decrease in size of the active region with age (P [less than] 0.05). fMRS results showed a significant decrease in glutamate change with stimulation (?Glu) with age (P < 0.05), and ?Glu became negative from 12 months onwards. Global CBF remained constant for the duration of the study. This study shows age related changes in the blood oxygen level dependent (BOLD) response in rodents that correlate with those seen in humans. The results also suggest that a reduction in synaptic glutamate turnover with age may underlie the reduction in the BOLD response, while CBF is preserved

Occupational differences, cardiovascular risk factors and lifestyle habits in South Eastern rural Australia

BACKGROUND: In rural and remote Australia, cardiovascular mortality and morbidity rates are higher than metropolitan rates.This study analysed cardiovascular and other chronic disease risk factors and related health behaviours by occupational status, to determine whether agricultural workers have higher cardiovascular disease (CVD) risk than other rural workers. METHODS: Cross-sectional surveys in three rural regions of South Eastern Australia (2004-2006). A stratified random sample of 1001 men and women aged 25-74 from electoral rolls were categorised by occupation into agricultural workers (men = 214, women = 79), technicians (men = 123), managers (men = 148, women = 272) and 'home duties' (women = 165). Data were collected from self-administered questionnaire, physical measurements and laboratory tests. Cardiovascular disease (CVD) and coronary heart disease (CHD) risk were assessed by Framingham 5 years risk calculation. RESULTS: Amongst men, agricultural workers had higher occupational physical activity levels, healthier more traditional diet, lower alcohol consumption, lower fasting plasma glucose, the lowest proportion of daily smokers and lower age-adjusted 5 year CVD and CHD risk scores.Amongst women, managers were younger with higher HDL cholesterol, lower systolic blood pressure, less hypertension, lower waist circumference, less self-reported diabetes and better 5 year CVD and CHD risk scores.Agricultural workers did not have higher cardiovascular disease risk than other occupational groups. CONCLUSIONS: Previous studies have suggested that farmers have higher risks of cardiovascular disease but this is because the risk has been compared with non-rural populations. In this study, the comparison has been made with other rural occupations. Cardiovascular risk reduction programs are justified for all. Programs tailored only for agricultural workers are unwarranted

Use of electronic patient data overview with alerts in primary care increases prescribing of lipid-lowering medications in patients with type 2 diabetes

AIMS/HYPOTHESIS: We aimed to assess whether general practices (GPs) using an electronic disease management program (DMP) with population overviews, including alerts when patients failed to receive guideline-recommended prescription medications, increased prescriptions of lipid-lowering drugs for patients with type 2 diabetes with no history of lipid-lowering treatment. METHODS: This observational study included 165 GPs that reached a high level of use of the DMP in 2012 and a control group of 135 GPs who reached a high level of use in 2013 and, hence, who were less exposed to the DMP throughout 2012. A binary measure for having been prescribed and filled lipid-lowering drugs at any time within a 12-month exposure period was derived for all patients with type 2 diabetes who did not receive a prescription for lipid-lowering drugs in the baseline year prior to the study period (i.e. 2011). Results were derived using ORs from multivariate logistic regression analyses. Subgroup stratification based on age, sex, diabetes duration, deprivation status and Charlson Comorbidity Index (CCI) score was conducted and assessed. Placebo tests were carried out to assess bias from selection to treatment. RESULTS: Patients who did not receive a prescription of lipid-lowering drugs in the year prior to being listed with GPs that used the DMP had statistically significant greater odds of receiving a prescription of lipid-lowering medications when compared with individuals who attended control GPs (OR 1.23 [95% CI 1.09, 1.38]). When the analysis period was shifted back by 2 years, no significant differences in lipid-lowering drug prescription between the two groups were found to occur, which indicates that these results were not driven by selection bias. Subgroup analyses showed that the increase in lipid-lowering drug prescriptions was primarily driven by changes among male participants (OR 1.32 [95% CI 1.12, 1.54]), patients aged 60–70 years (OR 1.40 [95% CI 1.13, 1.74]), patients with a diabetes duration of ≤5 years (OR 1.33 [95% CI 1.13, 1.56]), non-deprived patients (OR 1.25 [95% CI 1.08, 1.45]) and patients without comorbidities (CCI score = 0; OR 1.27 [95% CI 1.11, 1.45]). CONCLUSIONS/INTERPRETATION: Access to population overviews using a DMP with alerts of clinical performance measures with regard to adhering to guideline-recommended prescription of medications can increase GP prescriptions of lipid-lowering drugs. GRAPHICAL ABSTRACT: [Image: see text] SUPPLEMENTARY INFORMATION: The online version contains peer-reviewed but unedited supplementary material available at 10.1007/s00125-021-05598-x

Systematic review on barriers and facilitators of complex interventions for residents with dementia in long-term care

Objectives:Psychotropic drugs are frequently and sometimes inappropriately used for the treatment of neuropsychiatric symptoms of people with dementia, despite their limited efficacy and side effects. Interventions to address neuropsychiatric symptoms and psychotropic drug use are multifactorial and often multidisciplinary. Suboptimal implementation of these complex interventions often limits their effectiveness. This systematic review provides an overview of barriers and facilitators influencing the implementation of complex interventions targeting neuropsychiatric symptoms and psychotropic drug use in long-term care.Design:To identify relevant studies, the following electronic databases were searched between 28 May and 4 June: PubMed, Web of Science, PsycINFO, Cochrane, and CINAHL. Two reviewers systematically reviewed the literature, and the quality of the included studies was assessed using the Critical Appraisal Skills Programme qualitative checklist. The frequency of barriers and facilitators was addressed, followed by deductive thematic analysis describing their positive of negative influence. The Consolidated Framework for Implementation Research guided data synthesis.Results:Fifteen studies were included, using mostly a combination of intervention types and care programs, as well as different implementation strategies. Key factors to successful implementation included strong leadership and support of champions. Also, communication and coordination between disciplines, management support, sufficient resources, and culture (e.g. openness to change) influenced implementation positively. Barriers related mostly to unstable organizations, such as renovations to facility, changes toward self-directed teams, high staff turnover, and perceived work and time pressures.Conclusions:Implementation is complex and needs to be tailored to the specific needs and characteristics of the organization in question. Champions should be carefully chosen, and the application of learned actions and knowledge into practice is expected to further improve implementation