Investigation of wake breakdown in hover using the HMB3 solver

The present study forms an investigation of wake breakdown in hover using the HMB3 solver. Simulations are performed for the PSP rotor blade in hover on a grid aimed at resolving the detailed flow structures in the rotor wake. An assessment of different solver settings is per- formed including time discretisation, spatial discretisation accuracy and turbulence modelling on the rotor wake resolution and formation of instabilities. A particular focus is put on the existence and resolution of S-shaped structures due to the interactions of the blade tip vortices with the shear layers

Validation of the steady state hover formulation for accurate performance predictions

This paper shows accurate predictions for hover performance regardless of planform geometry, blade-tip Mach number, or disk loading. To prove this statement, sensitivity analyses were performed along with performance predictions for four rotor designs. Planform effects were also studied, such as the blade anhedral, showing the strong sensitivity of the rotor blade performance due to geometric features. The steady-state solution methodology with imposed Froude boundary conditions is shown to give accurate results for relatively coarse grid sizes. This approach leads to reduced computational costs as compared to time-dependent simulations. It is also recognized that, given the current accuracy of the available experimental data, the use of more advanced computational fluid dynamics methods may not be fully justified. To advance the accuracy of modern computational fluid dynamics methods, a comprehensive experimental dataset is required

High Fidelity Code-to-Code Comparison of Rotor Performance in Hover and Forward Flight

No abstract available

Determinants of Spirometry Use and Accuracy of COPD Diagnosis in Primary Care

BACKGROUND: It is unclear if primary care physicians are following guidelines or using other patient characteristics and factors to determine when to perform spirometry in patients at risk for COPD. It is also unclear to what degree a diagnosis of COPD is accurately reflected by spirometry results. OBJECTIVES: To examine characteristics associated with use of spirometry in primary care for patients with increased risk for COPD and to determine the accuracy of COPD diagnosis in patients with spirometry. DESIGN: Retrospective cohort study. SUBJECTS: A cohort that met the following criteria was identified: ≥35 years of age; ≥ 2 primary care visits in internal medicine clinic in 2007; at least one respiratory or smoking cessation medication, or diagnosis of COPD or shortness of breath or dyspnea in 2007. MAIN MEASURES: Medical records of all primary care physician visits prior to the time of inclusion in 2007 were reviewed. Data on patient demographics, co-morbidities, respiratory medication use, presence of symptoms, history of tobacco use, and pulmonary function tests were extracted. KEY RESULTS: A total 1052 patients were identified. Dyspnea on exertion (Adjusted odds ratio (AOR) 1.52 [95% CI 1.06-2.18]) and chronic cough (AOR 1.71 [1.07-2.72]) were the only chronic symptoms associated with use of spirometry. Current (AOR 1.54 [0.99-2.40]) or past smoking (AOR 1.09 [0.72-1.65]) status were not associated with use of spirometry. Of the 159 patients with a diagnosis of COPD, 93 (58.5%) met GOLD criteria and 81(50.9%) met lower limit of normal (LLN) criteria for COPD. CONCLUSION: Clinicians use spirometry more often among patients with symptoms suggestive of COPD but not more often among patients with current or past tobacco use. For patients who had a spirometry and a diagnosis of COPD, primary care physicians were accurate in their diagnosis only half of the time

High Fidelity Code-to-Code Comparison of Rotor Performance in Hover and Forward Flight

No abstract available

A limited role for TP53 mutation in the transformation of follicular lymphoma to diffuse large B-cell lymphoma

The role of TP53 mutation in transformation of follicular lymphoma (FL) to diffuse large B-cell lymphoma (t-FL) was examined in a panel of 91 lymph node biopsies derived from 29 patients pre- and post-transformation. The entire TP53 coding sequence was screened and immunocytochemistry performed to determine expression of p53 and its key regulator MDM2. A total of 10 mutations were detected in eight patients (28%), although none were present at FL diagnosis. Mutations were not detected solely at the time of transformation; in three patients, mutated TP53 arose in at least one antecedent FL sample (6 months, 2.5 years and 4 years prior to transformation). Loss of heterozygosity at the TP53 locus occurred in 2/20 informative patients (only in t-FL samples). p53 staining was positive in 82% (9/11) of available biopsies with a missense mutation, and negative in 71% (45/63) with wtTP53. MDM2 expression was significantly higher in t-FL samples (mean 72% positive; 95% confidence interval (95% CI) 68–76%) than FL (mean 58% positive; 95% CI 54–62%) (P<0.001) but did not correlate with TP53 status. TP53 mutation has only a limited role in the transformation of FL, exerting a heterogeneous influence upon phenotypic change. In contrast, dysregulation of MDM2 is frequent and may provide a more rational therapeutic target