Experimental evaluation of the effect of inlet distortion on compressor blade vibrations

Compressor rotor strain gage data from an engine test conducted with an inlet screen distortion were reduced and analyzed. These data are compared to data obtained from the same engine without inlet pressure distortion to determine the net effect of the distortion on the vibratory response of the compressor blades. The results obtained are presented

Characteristics of aeroelastic instabilities in turbomachinery - NASA full scale engine test results

Several aeromechanical programs were conducted in the NASA/USAF Joint Engine System Research Programs. The scope of these programs, the instrumentation, data acquisition and reduction, and the test results are discussed. Data pertinent to four different instabilities were acquired; two types of stall flutter, choke flutter and a system mode instability. The data indicates that each instability has its own unique characteristics. These characteristics are described

Interventions for neurocognitive dysfunction

Purpose of review: To evaluate current barriers to HIV cure strategies and interventions for neurocognitive dysfunction with a particular focus on recent advancements over the last three years. Recent findings: Optimal anti-retroviral therapy (ART) poses challenges to minimise neurotoxicity, whilst ensuring blood brain barrier penetration and minimising the risk of cerebrovascular disease. CSF biomarkers, BCL11B and neurofilament light chain may be implicated with a neuroinflammatory cascade leading to cognitive impairment. Diagnostic imaging with diffusion tensor imaging as well as resting-state fMRI show promise in future diagnosis and monitoring of HAND. Summary: The introduction of ART has resulted in a dramatic decline in HIV-associated dementia. Despite this reduction, milder forms of HIV-associated neurocognitive disorder (HAND) are still prevalent and are clinically significant. The central nervous system (CNS) has been recognised as a probable reservoir and sanctuary for HIV, representing a significant barrier to management interventions

The role of the gut and the gastrointestinal microbiome in Parkinson’s disease

INTRODUCTION: Parkinson’s disease (PD) is a disabling and progressive neurodegenerative disorder that is increasing in prevalence with the aging and urbanisation of the global population. The mechanisms underlying PD pathogenesis and progression are incompletely understood. Improved clinical recognition of early and prodromal non-motor symptoms (NMS), namely gastrointestinal (GI) dysfunction, has focused research over the last two decades on the roles of the gut. More recently, the influences of the microbiota-gut-brain-axis (MGBA) in the development and progression of PD have become an intensive area of research. Studies have demonstrated an association between the GM and a variety of PD-related characteristics, identifying important impacts on levodopa metabolism by certain microbiota. Importantly, the effect of device-assisted therapies (DATs) on the GM and the robustness of microbiota compositional differences between PD patients and household controls (HCs) has not been well defined. The aims of this thesis were to 1) investigate GI dysfunction and nutritional patterns in PD, 2) determine if the GM is a biomarker of PD, and 3) investigate the temporal stability of the GM in PD patients receiving standard therapies and those initiating DATs. METHODS: 103 PD patients and 81 HCs were recruited and participants with PD were considered in two sub-cohorts; 1) PD patients initiating DAT; either Deep Brain Stimulation (DBS) (n=10), or levodopa-carbidopa intestinal gel (LCIG) (n=11), who had GM sampling from stool at -2, 0, 2 and 4 weeks around initiation of DAT and baseline, 6 and 12 months following DAT initiation, 2) 82 PD patients receiving standard PD therapies, who had GM sampling from stool at baseline, 6 and 12 months. Validated PD questionnaire metadata ascertaining motor characteristics and NMS, as well as nutritional data in the form of a Food Frequency Questionnaire, were collected for all participants at baseline, 6 and 12 months. Total DNA was isolated from stool before sequencing the V3-V4 region of 16S rRNA. Relative bacterial abundances, diversity measures, compositional differences and clinical-microbiome associations were determined, as well as developing predictive modelling to identify PD patients and assess disease progression. RESULTS: PD patients reported more prevalent and severe GI dysfunction, especially constipation, which was almost three-times more common compared to HC subjects, (78.6% vs 28.4%, p<0.001). PD patients had a higher intake of total carbohydrates (279 g/day vs 232 g/day; p=0.034), which was largely attributable to an increased daily sugar intake (153 g/day vs 119 g/day; p=0.003), particularly of free sugars (61 g/day vs 41 g/day; p=0.001). Significant GM compositional differences across several taxonomic levels were apparent between PD patients and HCs and associated with a number of PD motor and NMS features, as well as certain therapies. Predictive models to distinguish PD from HCs were developed considering global GM profiles, achieving an area under the curve (AUC) of 0.71, which was improved by addition of data on carbohydrate intake (AUC 0.74). Longitudinal analysis demonstrated persistent underrepresentation of known short-chain fatty acid producing bacteria in PD patients, particularly those concerned with butyrate production; Butyricicoccus, Fusicatenibacter, Lachnospiraceae ND3007 group and Erysipelotrichaceae UCG−003. Taxa differences observed over the short-term (four week) sampling period around DAT (DBS and LCIG) initiation, were not sustained at 6 and 12 months. Despite this, persistent longer-term overrepresentation of Prevotella was observed after DBS initiation, and a trend was found that was suggestive of overrepresentation of Roseburia after LCIG initiation. These results suggest that there may be variable shorter and longer-term DBS and LCIG influences on the GM, which are complex and multifactorial. PD progression analysis did not identify distinct persisting GM compositional differences between faster and slower progressing patients, although predictive modelling was strengthened by the consideration of nutritional data, specifically protein intake, and improved the predictive capacity for PD progression. CONCLUSION: This thesis demonstrates that there are numerous clinically significant associations between the gut, GM and PD. GI dysfunction is common, and carbohydrate nutritional intake appears to be different from the general population in PD. Persistent alterations of GM composition in PD compared to HCs were found. These findings provide support for the existence of disturbances of gut homeostatic pathways, which may disrupt intestinal barrier permeability and lead to gut leakiness, in the pathogenesis of PD. This thesis also highlights the potential to use the GM in the identification of PD and the characterisation of disease progression

Isolated intractable nausea and vomiting with hiccups heralds a neuromyelitis optica area postrema syndrome

No abstract is available for this article

Hospitalisation and comorbidities in Parkinson\u27s disease: A large Australian retrospect study

Parkinson’s disease (PD) is a progressive and disabling neurological disorder that affects approximately 1% of the adult population aged over 65 years in Australia. Parkinson’s disease, as with many other chronic illnesses, results in frequent patient hospitalisations. There is a paucity of information on the causes and related co-morbidities that lead to hospitalisation among these patients in an Australian setting. The aim of this study was to examine patterns of hospitalisation of Parkinson’s disease patients with regards to demographic factors, co-morbidities and aspects relating to clinical management. In this study, data was extracted from the NSW Ministry of Health’s Admitted Patient Data Collection (APDC), to examine patterns of the patient admission over a five-year period. A comparison group (patients without Parkinson’s disease) was used to strengthen the study and to compare the epidemiological, demographic and clinical features if the Parkinson’s disease patients with those of patients without Parkinson’s disease. Statistical analysis of patterns of disease that may predispose Parkinson’s disease patients to hospitalisation was undertaken. The results of this retrospective study were used to inform patient groups and health care providers about the possibilities for improved health outcomes for patients and their carers and were published in the Journal of Neurology, Neurosurgery and Psychiatry in 2014

Status of NASA full-scale engine aeroelasticity research

Data relevant to several types of aeroelastic instabilities were obtained using several types of turbojet and turbofan engines. In particular, data relative to separated flow (stall) flutter, choke flutter, and system mode instabilities are presented. The unique characteristics of these instabilities are discussed, and a number of correlations are presented that help identify the nature of the phenomena

International Workshop on Vibration Isolation Technology for Microgravity Science Applications

The International Workshop on Vibration Isolation Technology for Microgravity Science Applications was held on April 23-25, 1991 at the Holiday Inn in Middleburg Heights, Ohio. The main objective of the conference was to explore vibration isolation requirements of space experiments and what level of vibration isolation could be provided both by present and planned systems on the Space Shuttle and Space Station Freedom and by state of the art vibration isolation technology

Bending-torsion flutter of a highly swept advanced turboprop

Experimental and analytical results are presented for a bending-torsion flutter phenomena encountered during wind-tunnel testing of a ten-bladed, advanced, high-speed propeller (turboprop) model with thin airfoil sections, high blade sweep, low aspect ratio, high solidity and transonic tip speeds. Flutter occurred at free-stream Mach numbers of 0.6 and greater and when the relative tip Mach number (based on vector sum of axial and tangential velocities) reached a value of about one. The experiment also included two- and five-blade configurations. The data indicate that aerodynamic cascade effects have a strong destabilizing influence on the flutter boundary. The data was correlated with analytical results which include aerodynamic cascade effects and good agreement was found

Gastrointestinal dysfunction in Parkinson\u27s disease

Background: Gastrointestinal (GI) dysfunction is prevalent in Parkinson’s disease (PD). Symptoms are evident throughout the disease course, affect the length of the GI tract and impact on patient quality of life and management. We clarify real-life differences in the frequency and severity of GI symptoms in a cohort of PD and healthy control (HC) subjects. Methods: 103 PD patients were compared to 81 HC subjects. Outcome measures collected from validated questionnaires included constipation severity, upper and lower GI symptoms and physical activity. Results: PD patients were three-times more likely to experience constipation than HC subjects, (78.6% vs 28.4%), exhibited a fourfold increase in constipation severity and formed harder stools. PD patients also reported increased symptoms of indigestion, nausea, excessive fullness and bloating, compared to the HCs. A higher mean Leeds Dyspepsia Questionnaire score for PD patients (8.3 (standard deviation (SD) 7.7) vs 4.6 (SD 6.1), p=0.001)) indicated increased symptom severity. Chronic pain was more frequently reported and correlated with constipation and upper GI dysfunction, being more prevalent and severe in women. Physical activity was notably decreased in the PD cohort (1823.6 (±1693.6) vs 2942.4 (±2620.9) metabolic equivalent-minutes/week, p=0.001) and correlated with constipation severity. PD therapies were associated with increased fullness and bloating and harder stools. Conclusions: PD patients report more prevalent and severe GI dysfunction, although our cohort comprised of many later stage participants. Earlier recognition of GI dysfunction in PD provides the opportunity to direct treatment for chronic pain and constipation, promote physical activity and rationalise PD therapies for optimal patient care