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Computational fluid dynamics

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https://www.readbyqxmd.com/read/28548989/imaging-adult-patients-with-fontan-circulation
#1
Salil Ginde, Benjamin H Goot, Peter C Frommelt
PURPOSE OF REVIEW: Survival after the Fontan procedure for palliation of single ventricle congenital heart disease has improved. However, adults with Fontan circulation are at risk for several complications including heart failure, thromboembolism, and protein-losing enteropathy. This review discusses the role of noninvasive imaging for surveillance and early detection of anatomic and functional abnormalities of the Fontan circulation that can impact the risk for Fontan failure over time...
May 25, 2017: Current Opinion in Cardiology
https://www.readbyqxmd.com/read/28547013/new-cfd-tools-to-evaluate-nasal-airflow
#2
M A Burgos, E Sanmiguel-Rojas, C Del Pino, M A Sevilla-García, F Esteban-Ortega
Computational fluid dynamics (CFD) is a mathematical tool to analyse airflow. As currently CFD is not a usual tool for rhinologists, a group of engineers in collaboration with experts in Rhinology have developed a very intuitive CFD software. The program MECOMLAND(®) only required snapshots from the patient's cross-sectional (tomographic) images, being the output those results originated by CFD, such as airflow distributions, velocity profiles, pressure, temperature, or wall shear stress. This is useful complementary information to cover diagnosis, prognosis, or follow-up of nasal pathologies based on quantitative magnitudes linked to airflow...
May 25, 2017: European Archives of Oto-rhino-laryngology
https://www.readbyqxmd.com/read/28544511/computational-fluid-dynamics-evaluation-of-posterior-septectomy-as-a-viable-treatment-option-for-large-septal-perforations
#3
Bradley A Otto, Chengyu Li, Alexander A Farag, Benjamin Bush, Jillian P Krebs, Ryan D Hutcheson, Kanghyun Kim, Bhakthi Deshpande, Kai Zhao
BACKGROUND: Numerous surgical techniques exist to treat nasal septal perforation (NSP). The surgical closure of large NSPs (>2 cm) is still challenging. Posterior septectomy has been reported as a simple alternative to treat large NSP, yet its mechanisms for symptom relief are not clear, and if failed, its consequence cannot be easily reversed. METHODS: Ten NSP patients were recruited: 5 underwent posterior septectomy and 5 underwent conventional flap or button repair...
May 23, 2017: International Forum of Allergy & Rhinology
https://www.readbyqxmd.com/read/28542705/a-pump-free-microfluidic-3d-perfusion-platform-for-the-efficient-differentiation-of-human-hepatocyte-like-cells
#4
Louis Jun Ye Ong, Lor Huai Chong, Lin Jin, Pawan Kumar Singh, Poh Seng Lee, Hanry Yu, Abhishek Ananthanarayanan, Hwa Liang Leo, Yi-Chin Toh
The practical application of microfluidic liver models for in vitro drug testing is partly hampered by their reliance on human primary hepatocytes, which are limited in number and have batch-to-batch variation. Human stem cell-derived hepatocytes offer an attractive alternative cell source, although their 3D differentiation and maturation in a microfluidic platform have not yet been demonstrated. We develop a pump-free microfluidic 3D perfusion platform to achieve long-term and efficient differentiation of human liver progenitor cells into hepatocyte-like cells (HLCs)...
May 20, 2017: Biotechnology and Bioengineering
https://www.readbyqxmd.com/read/28542193/an-agent-based-model-of-leukocyte-transendothelial-migration-during-atherogenesis
#5
Rita Bhui, Heather N Hayenga
A vast amount of work has been dedicated to the effects of hemodynamics and cytokines on leukocyte adhesion and trans-endothelial migration (TEM) and subsequent accumulation of leukocyte-derived foam cells in the artery wall. However, a comprehensive mechanobiological model to capture these spatiotemporal events and predict the growth and remodeling of an atherosclerotic artery is still lacking. Here, we present a multiscale model of leukocyte TEM and plaque evolution in the left anterior descending (LAD) coronary artery...
May 2017: PLoS Computational Biology
https://www.readbyqxmd.com/read/28539480/identification-of-vortex-structures-in-a-cohort-of-204-intracranial-aneurysms
#6
Nicole Varble, Gabriel Trylesinski, Jianping Xiang, Kenneth Snyder, Hui Meng
An intracranial aneurysm (IA) is a cerebrovascular pathology that can lead to death or disability if ruptured. Abnormal wall shear stress (WSS) has been associated with IA growth and rupture, but little is known about the underlying flow physics related to rupture-prone IAs. Previous studies, based on analysis of a few aneurysms or partial views of three-dimensional vortex structures, suggest that rupture is associated with complex vortical flow inside IAs. To further elucidate the relevance of vortical flow in aneurysm pathophysiology, we studied 204 patient IAs (56 ruptured and 148 unruptured)...
May 2017: Journal of the Royal Society, Interface
https://www.readbyqxmd.com/read/28535909/dynamic-simulation-and-doppler-ultrasonography-validation-of-blood-flow-behavior-in-abdominal-aortic-aneurysm
#7
Cristian C Botar, Árpád Á Tóth, Olivera R Klisurić, Dijana D Nićiforović, Viktorija A Vučaj Ćirilović, Viktor E Till
Criteria for rupture prediction of Abdominal Aortic Aneurysm (AAA) are based only on the diameter of AAA. This method does not consider complex hemodynamic forces exerted on AAA wall. The methodology used in our study combines Computer-Aided Design (CAD) with Computational Fluid Dynamics (CFD). Three-dimensional vascular structures reconstructions were based on Computed Tomography (CT) images and CAD. CFD theory was used for mathematical modeling and simulations. In this way, dynamic behavior of blood flow in bounded three-dimensional space was described...
May 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/28535342/diffusion-under-confinement-hydrodynamic-finite-size-effects-in-simulation
#8
Pauline Simonnin, Benoit Noetinger, Carlos Nieto Draghi, Virginie Marry, Benjamin Rotenberg
We investigate finite-size effects on diffusion in confined fluids using molecular dynamics simulations and hydrodynamic calculations. Specifically, we consider a Lennard-Jones fluid in slit pores without slip at the interface and show that the use of periodic boundary conditions in the directions along the surfaces results in dramatic finite-size effects, in addition to that of the physically relevant confining length. As in the simulation of bulk fluids, these effects arise from spurious hydrodynamic interactions between periodic images and from the constraint of total momentum conservation...
May 23, 2017: Journal of Chemical Theory and Computation
https://www.readbyqxmd.com/read/28530257/mathematical-model-for-preoperative-identification-of-obstructed-nasal-subsites
#9
M Gamerra, E Cantone, G Sorrentino, R De Luca, M B Russo, E De Corso, F Bossa, A De Vivo, M Iengo
The planning of experimental studies for evaluation of nasal airflow is particularly challenging given the difficulty in obtaining objective measurements in vivo. Although standard rhinomanometry and acoustic rhinometry are the most widely used diagnostic tools for evaluation of nasal airflow, they provide only a global measurement of nasal dynamics, without temporal or spatial details. Furthermore, the numerical simulation of nasal airflow as computational fluid dynamics technology is not validated. Unfortunately, to date, there are no available diagnostic tools to objectively evaluate the geometry of the nasal cavities and to measure nasal resistance and the degree of nasal obstruction, which is of utmost importance for surgical planning...
May 22, 2017: Acta Otorhinolaryngologica Italica
https://www.readbyqxmd.com/read/28527110/a-review-of-the-hemodynamic-factors-believed-to-contribute-to-vascular-access-dysfunction
#10
Connor V Cunnane, Eoghan M Cunnane, Michael T Walsh
A vascular access (VA) is used to facilitate hemodialysis in patients that suffer from end-stage renal disease. However, they suffer from high failure rates due to non-maturation and venous stenosis, with intimal hyperplasia (IH) the underlying cause of both conditions. Abnormal hemodynamic profiles, which arise following VA creation, are believed to lead to the development of IH. However, the exact physiological response that initiates this process is unknown. This review evaluates the different hemodynamic parameters that are hypothesised to correlate with the development of IH...
May 19, 2017: Cardiovascular Engineering and Technology
https://www.readbyqxmd.com/read/28525548/computational-fluid-dynamics-characterization-of-pulsatile-flow-in-central-and-sano-shunts-connected-to-the-pulmonary-arteries-importance-of-graft-angulation-on-shear-stress-induced-platelet-mediated-thrombosis
#11
Robert Ascuitto, Nancy Ross-Ascuitto, Martin Guillot, Carey Celestin
OBJECTIVES: Central (aorta) and Sano (right ventricle)-to-pulmonary artery (PA) shunts, palliative operations for infants with complex heart defects, can develop life-threatening thrombosis. We employed computational fluid dynamics (CFD) to study pulsatile flow in these shunts, with the goal to identify haemodynamic characteristics conducive to thrombus formation. METHODS: CFD, using the finite volume method with cardiac catheterization data, and computer simulations, based on angiography, were employed to determine flow-velocity field, wall shear stress (WSS) profile and oscillatory shear index (OSI)...
May 19, 2017: Interactive Cardiovascular and Thoracic Surgery
https://www.readbyqxmd.com/read/28523829/the-prediction-of-viscous-losses-and-pressure-drop-in-models-of-the-human-airways
#12
A K Wells, I P Jones, S Hamill, R Bordas
This paper examines the viscous flow resistance in branching tubes as applied to simplified models of the lungs, and compares the results of Computational Fluid Dynamics (CFD) simulations for a range of conditions with measurement data. The results are in good agreement with the available measurement data for both inspiration and expiration. A detailed sensitivity analysis of the dissipation and viscous resistance in a branch then examines the ratio of the viscous resistance to that for a fully developed Poiseuille flow, Z...
May 18, 2017: International Journal for Numerical Methods in Biomedical Engineering
https://www.readbyqxmd.com/read/28521764/barrier-dysfunction-or-drainage-reduction-differentiating-causes-of-csf-protein-increase
#13
Mahdi Asgari, Diane A de Zélicourt, Vartan Kurtcuoglu
BACKGROUND: Cerebrospinal fluid (CSF) protein analysis is an important element in the diagnostic chain for various central nervous system (CNS) pathologies. Among multiple existing approaches to interpreting measured protein levels, the Reiber diagram is particularly robust with respect to physiologic inter-individual variability, as it uses multiple subject-specific anchoring values. Beyond reliable identification of abnormal protein levels, the Reiber diagram has the potential to elucidate their pathophysiologic origin...
May 18, 2017: Fluids and Barriers of the CNS
https://www.readbyqxmd.com/read/28515570/association-between-hemodynamic-modifications-and-clinical-outcome-of-intracranial-aneurysms-treated-using-flow-diverters
#14
Nikhil Paliwal, Robert J Damiano, Jason M Davies, Adnan H Siddiqui, Hui Meng
Treatment of intracranial aneurysms (IAs) has been revolutionized by the advent of endovascular Flow Diverters (FDs), which disrupt blood flow within the aneurysm to induce pro-thrombotic conditions, and serves as a scaffold for endothelial ingrowth and arterial remodeling. Despite good clinical success of FDs, complications like incomplete occlusion and post-treatment rupture leading to subarachnoid hemorrhage have been reported. In silico computational fluid dynamic analysis of the pre- and post-treated geometries of IA patients can shed light on the contrasting blood hemodynamics associated with different clinical outcomes...
February 11, 2017: Proceedings of SPIE
https://www.readbyqxmd.com/read/28515420/vascular-remodelling-relates-to-an-elevated-oscillatory-shear-index-and-relative-residence-time-in-spontaneously-hypertensive-rats
#15
Zhiyan Chen, Haiyi Yu, Yue Shi, Minjia Zhu, Yueshen Wang, Xi Hu, Youyi Zhang, Yu Chang, Ming Xu, Wei Gao
Haemodynamic disorders are common clinical findings in hypertension and lead to adverse cardiovascular events. However, the haemodynamic conditions in hypertension models are poorly understood. This study aimed to observe the characteristics of haemodynamics in spontaneously hypertensive rats (SHRs) and antihypertensive-treated SHRs. Twenty-four adult male SHRs and Wistar-Kyoto rats (WKYs) were randomly divided into four groups and treated for 7 days as follows: WKY-CON (WKYs + saline), WKY-NIF (WKYs + nifedipine, 50 mg/kg/day), SHR-CON (SHRs + saline), and SHR-NIF (SHRs + nifedipine)...
May 17, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28515329/inference-of-facultative-mobility-in-the-enigmatic-ediacaran-organism-parvancorina
#16
Simon A F Darroch, Imran A Rahman, Brandt Gibson, Rachel A Racicot, Marc Laflamme
Establishing how Ediacaran organisms moved and fed is critical to deciphering their ecological and evolutionary significance, but has long been confounded by their non-analogue body plans. Here, we use computational fluid dynamics to quantitatively analyse water flow around the Ediacaran taxon Parvancorina, thereby testing between competing models for feeding mode and mobility. The results show that flow was not distributed evenly across the organism, but was directed towards localized areas; this allows us to reject osmotrophy, and instead supports either suspension feeding or detritivory...
May 2017: Biology Letters
https://www.readbyqxmd.com/read/28512709/influence-of-low-temperature-combustion-and-dimethyl-ether-diesel-blends-on-performance-combustion-and-emission-characteristics-of-common-rail-diesel-engine-a-cfd-study
#17
Venkatesh Tavareppa Lamani, Ajay Kumar Yadav, Kumar Gottekere Narayanappa
Due to presence of more oxygen, absence of carbon-carbon (C-C) bond in chemical structure, and high cetane number of dimethyl ether (DME), pollution from DME operated engine is less compared to diesel engine. Hence, the DME can be a promising alternative fuel for diesel engine. The present study emphasizes the effect of various exhaust gas recirculation (EGR) rates (0-20%) and DME/Diesel blends (0-20%) on combustion characteristics and exhaust emissions of common rail direct injection (CRDI) engine using three-dimensional computational fluid dynamics (CFD) simulation...
May 16, 2017: Environmental Science and Pollution Research International
https://www.readbyqxmd.com/read/28511839/the-implication-of-the-osteolysis-threshold-and-interfacial-gaps-on-periprosthetic-osteolysis-in-cementless-total-hip-replacement
#18
Hamidreza Alidousti, Neil W Bressloff
Osteolysis around joint replacements may develop due to migration of wear particles from the joint space into gaps between the interface bone and the implant where they can accumulate in high concentrations to cause tissue damage. Osteolysis may appear in various postoperative times and morphological shapes which can be generalized into linear and focal. However, there are no clear explanations on the causes of such variations. Patients' degree of sensitivity to polyethylene particles (osteolysis thresholds), the local particle concentration and the access route provided by the interface gaps have been described as determining factors...
May 5, 2017: Journal of Biomechanics
https://www.readbyqxmd.com/read/28511838/supra-annular-valve-in-valve-implantation-reduces-blood-stasis-on-the-transcatheter-aortic-valve-leaflets
#19
Koohyar Vahidkhah, Ali N Azadani
Leaflet thrombosis following transcatheter aortic valve replacement (TAVR) and Valve-in-Valve (ViV) procedures has been increasingly recognized. This study aimed to investigate the effect of positioning of the transcatheter aortic valve (TAV) in ViV setting on the flow dynamics aspect of post-ViV thrombosis by quantifying the blood stasis in the intra-annular and supra-annular settings. To that end, two idealized computational models, representing ViV intra-annular and supra-annular positioning of a TAV were developed in a patient-specific geometry...
May 5, 2017: Journal of Biomechanics
https://www.readbyqxmd.com/read/28508359/evolving-relevance-of-neuroproteomics-in-alzheimer-s-disease
#20
Simone Lista, Henrik Zetterberg, Sid E O'Bryant, Kaj Blennow, Harald Hampel
Substantial progress in the understanding of the biology of Alzheimer's disease (AD) has been achieved over the past decades. The early detection and diagnosis of AD and other age-related neurodegenerative diseases, however, remain a challenging scientific frontier. Therefore, the comprehensive discovery (relating to all individual, converging or diverging biochemical disease mechanisms), development, validation, and qualification of standardized biological markers with diagnostic and prognostic functions with a precise performance profile regarding specificity, sensitivity, and positive and negative predictive value are warranted...
2017: Methods in Molecular Biology
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