Nominal vs. effective wake fields and their influence on propeller cavitation performance

Propeller designers often need to base their design on the nominal model scale wake distribution because the effective full scale distribution is not available. The effects of such incomplete design data on cavitation performance are examined in this paper. The behind-ship cavitation performance of two propellers is evaluated, where the cases considered include propellers operating in the nominal model and full scale wake distributions and in the effective wake distribution, also in the model and full scale. The method for the analyses is a combination of RANS for the ship hull and a panel method for the propeller flow, with a coupling of the two for the interaction of ship and propeller flows. The effect on sheet cavitation due to the different wake distributions is examined for a typical full-form ship. Results show considerable differences in cavitation extent, volume, and hull pressure pulses

Fluid-structure interaction simulations of repaired type A aortic dissection: a comprehensive comparison with rigid wall models

This study aimed to evaluate the effect of aortic wall compliance on intraluminal hemodynamics within surgically repaired type A aortic dissection (TAAD). Fully coupled two-way fluid-structure interaction (FSI) simulations were performed on two patient-specific post-surgery TAAD models reconstructed from computed tomography angiography images. Our FSI model incorporated prestress and different material properties for the aorta and graft. Computational results, including velocity, wall shear stress (WSS) and pressure difference between the true and false lumen, were compared between the FSI and rigid wall simulations. It was found that the FSI model predicted lower blood velocities and WSS along the dissected aorta. In particular, the area exposed to low time-averaged WSS (≤0.2 Pa) was increased from 21 cm2 (rigid) to 38 cm2 (FSI) in patient 1 and from 35 cm2 (rigid) to 144 cm2 (FSI) in patient 2. FSI models also produced more disturbed flow where much larger regions presented with higher turbulence intensity as compared to the rigid wall models. The effect of wall compliance on pressure difference between the true and false lumen was insignificant, with the maximum difference between FSI and rigid models being less than 0.25 mmHg for the two patient-specific models. Comparisons of simulation results for models with different Young’s moduli revealed that a more compliant wall resulted in further reduction in velocity and WSS magnitudes because of increased displacements. This study demonstrated the importance of FSI simulation for accurate prediction of low WSS regions in surgically repaired TAAD, but a rigid wall computational fluid dynamics simulation would be sufficient for prediction of luminal pressure difference

The 7th lung cancer TNM classification and staging system:Review of the changes and implications

Lung cancer is the most common cause of death from cancer in males, accounting for more than 1.4 million deaths in 2008. It is a growing concern in China, Asia and Africa as well. Accurate staging of the disease is an important part of the management as it provides estimation of patient’s prognosis and identifies treatment sterategies. It also helps to build a database for future staging projects. A major revision of lung cancer staging has been announced with effect from January 2010. The new classification is based on a larger surgical and non-surgical cohort of patients, and thus more accurate in terms of outcome prediction compared to the previous classification. There are several original papers regarding this new classification which give comprehensive description of the methodology, the changes in the staging and the statistical analysis. This overview is a simplified description of the changes in the new classification and their potential impact on patients’ treatment and prognosis

Bronchial Artery Embolisation for Massive Haemoptysis: Immediate and Long-Term Outcomes-A Retrospective Study.

INTRODUCTION: Bronchial artery embolisation (BAE) is an established treatment method for massive haemoptysis. The aim of this study is to evaluate the impact of BAE on in-hospital outcomes and long-term survival in patients with massive haemoptysis. METHODS: Retrospective review of all cases of acute massive haemoptysis treated by BAE between April 2000 and April 2012 with at least a 5 year follow up of each patient. Targeted BAE was performed in cases with lateralising symptoms, bronchoscopic sites of bleeding or angiographic unilateral abnormal vasculature. In the absence of lateralising symptoms or signs, bilateral BAE was performed. RESULTS: 96 BAEs were performed in 68 patients. The majority (64 cases, 67%) underwent unilateral procedures. 83 (86.5%) procedures resulted in immediate/short term control of haemoptysis which lasted for longer than a month. The mean duration of haemoptysis free period after embolisation was 96 months. There were three major complications (cardio-pulmonary arrest, paraparesis and stroke). 38 (56%) patients were still alive at least 5 years following their BAE. Benign causes were associated with significantly longer haemoptysis free periods, mean survival 108 months compared to 32 months in patients with an underlying malignant cause (p = 0.005). An episode of haemoptysis within a month of the initial embolisation was associated reduced overall survival (p = 0.033). CONCLUSION: BAE is effective in controlling massive haemoptysis. Long-term survival depends on the underlying pulmonary pathology. Strategies are required to avoid incomplete initial embolisation, which is associated with ongoing haemoptysis and high mortality despite further BAE

Effects of Rosmarinus officinalis and Platanus orientalis extracts on asthmatic subjects resistant to routine treatments

Objective: The present study aimed to determine the effects of Rosmarinus officinalis (R. officinalis) and Platanus orientalis(P. orientalis) extracts on asthma. Materials and Methods: We conducted a randomized, double-blind, active-comparator study to evaluate the effect of P. orientalis and R. officinalis extracts on asthmatic patients resistant to routine treatment.The subjects were randomly divided into three groups receiving P. orientalis and R. officinalis extracts alone or in combination. The primary endpoints were clinical findings, spirometry, exhaled nitric oxide (FENO) and Asthma Control Test (ACT) assessed over the one-month treatment period. Results: ACT score showed significant improvement after treatment with R. officinalis (

Iterative reconstruction can permit the use of lower x-ray tube current in CT coronary artery calcium scoring

OBJECTIVE: CT coronary artery calcium scoring (CACS) is additive to traditional risk factors for predicting future cardiac events but is associated with relatively high radiation doses. We assessed the feasibility of CACS radiation dose reduction using a lower tube current and iterative reconstruction (IR). METHODS: Artificial noise was added to the raw data from 27 CACS studies from patients who were symptomatic to simulate lower tube current scanning (75, 50 and 25% original current). All studies were performed on the same CT scanner at 120 kVp. Data were reconstructed using filtered back projection [Quantum Denoising Software (QDS+)] and IR [adaptive iterative dose reduction three dimensional mild, standard and strong]. Agatston scores were independently measured by two readers. CACS percentile risk scores were calculated. RESULTS: At 75, 50 and 25% tube currents, all adaptive iterative dose reduction (AIDR) reconstructions decreased image noise relative to QDS+ (p < 0.05). All AIDR reconstructions resulted in small reductions in Agatston score relative to QDS+ at the standard tube current (p < 0.05). Agatston scores increased with QDS+ at 75, 50 and 25% tube current (p < 0.05), whereas no significant change was observed with AIDR mild at any tested tube current. No difference in the percentile risk score with AIDR mild at any tube current occurred compared with QDS+ at standard tube current (p > 0.05). Interobserver agreement for AIDR mild remained excellent even at 25% tube current (intraclass correlation coefficient 0.997). CONCLUSION: Up to 75% reduction in CACS tube current is feasible using AIDR mild. ADVANCES IN KNOWLEDGE: AIDR mild IR permits low tube current CACS whilst maintaining excellent intraobserver and interobserver variability and without altering risk classification