Influence of Inlet Secondary Curvature on Image-Based CFD Models of the Carotid Bifurcation

2008 ◽  
Author(s):  
Sang-Wook Lee ◽  
David A. Steinman
Keyword(s):  
Carotid Bifurcation ◽  
Velocity Profiles ◽  
Construction Process ◽  
Cfd Modelling ◽  
Measured Velocity ◽  
Cfd Models ◽  
Measured Flow ◽  
The Common ◽  
Made In

In image-based CFD modelling of carotid bifurcation hemodynamics, it is often not possible (or at least not convenient) to impose measured velocity profiles at the common carotid artery (CCA) inlet. Instead, fully-developed velocity profiles are usually imposed based on measured flow rates. Previous work from our group showed that this is reasonable [1], in the sense that errors made in doing so are substantially less than uncertainties inherent in the model construction process itself. In that study, long helical inlet sections were imposed to induce asymmetric (Dean-type) velocity flows profiles consistent with in vivo velocity profiles measured by others at the CCA [2, 3].

Hemodynamics in the abdominal aorta: a comparison of in vitro and in vivo measurements

1994 ◽  
Vol 76 (4) ◽  
pp. 1520-1527 ◽  
Author(s):  
J. E. Moore ◽  
S. E. Maier ◽  
D. N. Ku ◽  
P. Boesiger
Keyword(s):  
Abdominal Aorta ◽  
Velocity Profiles ◽  
Flow Reversal ◽  
Infrarenal Aorta ◽  
Complex Flow ◽  
Flow Measurements ◽  
In Vivo Measurements ◽  
Made In

In vivo measurements of blood velocity profiles are difficult to obtain and interpret, since the parameters that govern the normally highly complex flow situation may not be fully quantified or understood at the time of measurement. In vitro flow models have been used often to better understand vascular hemodynamics. The assumptions made in the design of these models limit the applicability of the results. In this study, in vitro flow measurements made in a carefully designed model of the abdominal aorta were compared with in vivo measurements obtained with magnetic resonance imaging. In the suprarenal aorta, the velocity profiles were mostly forward and axisymmetric in both the in vitro and in vivo cases. In the infrarenal aorta, there was extensive flow reversal noted near the posterior wall in both cases. In the aortic bifurcation, two peaks of flow reversal were noted near the lateral posterior walls, and M-shaped velocity profiles were observed in late diastole. The in vitro and in vivo measurements exhibited good qualitative agreement. The in vitro model was accurate in modeling the in vivo hemodynamics of the abdominal aorta. The complex phenomena observed in vivo were explained on the basis of knowledge gained from the in vitro study.

Chyavanprash: Choice of Drug for immunity boosting and health supplements during COVID -19 pandemic

2020 ◽  
Vol 11 (SPL1) ◽  
pp. 1346-1350
Author(s):  
Bharat Rathi ◽  
Renu Rathi ◽  
Vinod Ade ◽  
Akshay Pargaonkar
Keyword(s):  
Therapeutic Potential ◽  
Age Groups ◽  
Pharmacological Activities ◽  
Common People ◽  
The World ◽  
The Common ◽  
Made In ◽  
Health Supplements

Chyavanprash a known Ayurvedic formulation formulated by sage Chyavan to impart youth, charm, strength & prolonged life. It is very much valued for possessing numerous health benefits with respect to the preventive, curative and promotive aspects of health. Chyavanprash can be consumed throughout the year. Several scientific evidences support its wholesome and safe healthy tonic status that is favorable for all age groups and genders alike. In modern days, it has gained mammoth popularity throughout the world. CP is prepared with Amalaki (Emblica officinalis) as a prime drug with other nutrient rich herbs help to preserve stamina, strength and vitality. Various pre clinical (in vivo & in vitro), Experimental, Analytical and clinical studies conducted on CP and its individual components revealed its various pharmacological activities most of which are suggestive of immunity enhancer and health supplements. Hence an attempt is made in the present paper to find out and explore the scientific evidences based on therapeutic potential of CP with respect to immunity and health supplements and make evidences available to the common people to combat the COVID-19 menace effectively.

scholarly journals Choice of In Vivo Versus Idealized Velocity Boundary Conditions Influences Physiologically Relevant Flow Patterns in a Subject-Specific Simulation of Flow in the Human Carotid Bifurcation

2008 ◽  
Vol 131 (2) ◽  
Author(s):  
Amanda K. Wake ◽  
John N. Oshinski ◽  
Allen R. Tannenbaum ◽  
Don P. Giddens
Keyword(s):  
Carotid Artery ◽  
Boundary Conditions ◽  
Carotid Bifurcation ◽  
Flow Patterns ◽  
Flow Data ◽  
Measured Velocity ◽  
Carotid Artery Bifurcation ◽  
Subject Specific ◽  
Human Carotid

Accurate fluid mechanics models are important tools for predicting the flow field in the carotid artery bifurcation and for understanding the relationship between hemodynamics and the initiation and progression of atherosclerosis. Clinical imaging modalities can be used to obtain geometry and blood flow data for developing subject-specific human carotid artery bifurcation models. We developed subject-specific computational fluid dynamics models of the human carotid bifurcation from magnetic resonance (MR) geometry data and phase contrast MR velocity data measured in vivo. Two simulations were conducted with identical geometry, flow rates, and fluid parameters: (1) Simulation 1 used in vivo measured velocity distributions as time-varying boundary conditions and (2) Simulation 2 used idealized fully-developed velocity profiles as boundary conditions. The position and extent of negative axial velocity regions (NAVRs) vary between the two simulations at any given point in time, and these regions vary temporally within each simulation. The combination of inlet velocity boundary conditions, geometry, and flow waveforms influences NAVRs. In particular, the combination of flow division and the location of the velocity peak with respect to individual carotid geometry landmarks (bifurcation apex position and the departure angle of the internal carotid) influences the size and location of these reversed flow zones. Average axial wall shear stress (WSS) distributions are qualitatively similar for the two simulations; however, instantaneous WSS values vary with the choice of velocity boundary conditions. By developing subject-specific simulations from in vivo measured geometry and flow data and varying the velocity boundary conditions in otherwise identical models, we isolated the effects of measured versus idealized velocity distributions on blood flow patterns. Choice of velocity distributions at boundary conditions is shown to influence pathophysiologically relevant flow patterns in the human carotid bifurcation. Although mean WSS distributions are qualitatively similar for measured and idealized inlet boundary conditions, instantaneous NAVRs differ and warrant imposing in vivo velocity boundary conditions in computational simulations. A simulation based on in vivo measured velocity distributions is preferred for modeling hemodynamics in subject-specific carotid artery bifurcation models when studying atherosclerosis initiation and development.

Is Flow in the Common Carotid Artery Fully-Developed?

2008 ◽  
Author(s):  
Joyce Xie ◽  
Matthew D. Ford ◽  
David A. Steinman
Keyword(s):  
Carotid Artery ◽  
Velocity Profile ◽  
Common Carotid Artery ◽  
Velocity Profiles ◽  
Blood Velocity ◽  
Shear Stresses ◽  
Velocity Data ◽  
Flow Rates ◽  
The Common

It is usually assumed, in both clinical and experimental settings, that blood velocity profiles in the common carotid artery (CCA) are fully-developed. This allows for a simpler estimation of CCA flow rates or wall shear stresses (WSS) from limited velocity data, such as peak velocities acquired using Doppler ultrasound (DUS) [1]. However, the assumption of a long, straight CCA may be incorrect, as the CCA does possess some curvature [2], which may alter the velocity profile from the assumed Poiseuille or Womersley shapes, and thus lead to incorrect inferences about flow rate or WSS. Consequently, this may have an impact on our understanding and diagnoses of cardiovascular related diseases. The aim of this study was to characterize the real shape of CCA velocity profiles in vivo.

scholarly journals Effect of Common Carotid Artery Inlet Length on Normal Carotid Bifurcation Hemodynamics

2010 ◽  
Vol 132 (12) ◽  
Author(s):  
Yiemeng Hoi ◽  
Bruce A. Wasserman ◽  
Edward G. Lakatta ◽  
David A. Steinman
Keyword(s):  
Carotid Artery ◽  
Common Carotid Artery ◽  
Carotid Bifurcation ◽  
Velocity Profiles ◽  
Substantial Improvement ◽  
Disturbed Flow ◽  
Inlet Velocity ◽  
Cfd Models ◽  
Inlet Length ◽  
The Impact

Controversy exists regarding the suitability of fully developed versus measured inlet velocity profiles for image-based computational fluid dynamics (CFD) studies of carotid bifurcation hemodynamics. Here, we attempt to resolve this by investigating the impact of the reconstructed common carotid artery (CCA) inlet length on computed metrics of “disturbed” flow. Twelve normal carotid bifurcation geometries were reconstructed from contrast-enhanced angiograms acquired as part of the Vascular Aging—The Link That Bridges Age to Atherosclerosis study (VALIDATE). The right carotid artery lumen geometry was reconstructed from its brachiocephalic origin to well above the bifurcation, and the CCA was truncated objectively at locations one, three, five, and seven diameters proximal to where it flares into the bifurcation. Relative to the simulations carried out using the full CCA, models truncated at one CCA diameter strongly overestimated the amount of disturbed flow. Substantial improvement was offered by using three CCA diameters, with only minor further improvement using five CCA diameters. With seven CCA diameters, the amounts of disturbed flow agreed unambiguously with those predicted by the corresponding full-length models. Based on these findings, we recommend that image-based CFD models of the carotid bifurcation should incorporate at least three diameters of CCA length if fully developed velocity profiles are to be imposed at the inlet. The need for imposing measured inlet velocity profiles would seem to be relevant only for those cases where the CCA is severely truncated.

An Overview of Dementias

2012 ◽  
Vol 21 (3) ◽  
pp. 75-84
Author(s):  
Venkata Vijaya K. Dalai ◽  
Jason E. Childress ◽  
Paul E Schulz
Keyword(s):  
Clinical Presentation ◽  
Treatment Options ◽  
Current Treatment ◽  
Great Variability ◽  
Health Concern ◽  
Public Health Concern ◽  
Life Threatening ◽  
The Common ◽  
Neurodegenerative Dementias ◽  
Made In

Dementia is a major public health concern that afflicts an estimated 24.3 million people worldwide. Great strides are being made in order to better diagnose, prevent, and treat these disorders. Dementia is associated with multiple complications, some of which can be life-threatening, such as dysphagia. There is great variability between dementias in terms of when dysphagia and other swallowing disorders occur. In order to prepare the reader for the other articles in this publication discussing swallowing issues in depth, the authors of this article will provide a brief overview of the prevalence, risk factors, pathogenesis, clinical presentation, diagnosis, current treatment options, and implications for eating for the common forms of neurodegenerative dementias.

Cuckoo chicks evicting their nest mates: coincidental observations by Edward Jenner in England and Antoine Joseph Lottinger in France

2011 ◽  
Vol 38 (2) ◽  
pp. 220-228 ◽  
Author(s):  
Spencer G. Sealy ◽  
Mélanie F. Guigueno
Keyword(s):  
Royal Society ◽  
Cuculus Canorus ◽  
Common Cuckoo ◽  
Cuckoo Chick ◽  
The Common ◽  
Made In ◽  
Royal Society Of London

For centuries, naturalists were aware that soon after hatching the common cuckoo (Cuculus canorus) chick became the sole occupant of the fosterer's nest. Most naturalists thought the adult cuckoo returned to the nest and removed or ate the fosterer's eggs and young, or the cuckoo chick crowded its nest mates out of the nest. Edward Jenner published the first description of cuckoo chicks evicting eggs and young over the side of the nest. Jenner's observations, made in England in 1786 and 1787, were published by the Royal Society of London in 1788. Four years before Jenner's observations, in 1782, Antoine Joseph Lottinger recorded eviction behaviour in France and published his observations in Histoire du coucou d'Europe, in 1795. The importance of Lottinger's and Jenner's observations is considered together.

The Application of the Cold Atmospheric Plasma-Activated Solutions in Cancer Treatment

2018 ◽  
Vol 18 (6) ◽  
pp. 769-775 ◽  
Author(s):  
Dayun Yan ◽  
Jonathan H. Sherman ◽  
Michael Keidar
Keyword(s):  
Cancer Treatment ◽  
Atmospheric Plasma ◽  
Current Status ◽  
Cold Atmospheric Plasma ◽  
Anti Cancer ◽  
Long Time ◽  
Key Topics ◽  
The Common

Background: Over the past five years, the cold atmospheric plasma-activated solutions (PAS) have shown their promissing application in cancer treatment. Similar as the common direct cold plasma treatment, PAS shows a selective anti-cancer capacity in vitro and in vivo. However, different from the direct cold atmospheric plasma (CAP) treatment, PAS can be stored for a long time and can be used without dependence on a CAP device. The research on PAS is gradually becoming a hot topic in plasma medicine. Objectives: In this review, we gave a concise but comprehensive summary on key topics about PAS including the development, current status, as well as the main conclusions about the anti-cancer mechanism achieved in past years. The approaches to make strong and stable PAS are also summarized.

scholarly journals Stu2p binds tubulin and undergoes an open-to-closed conformational change

2006 ◽  
Vol 172 (7) ◽  
pp. 1009-1022 ◽  
Author(s):  
Jawdat Al-Bassam ◽  
Mark van Breugel ◽  
Stephen C. Harrison ◽  
Anthony Hyman
Keyword(s):  
Conformational Change ◽  
Conformational Transition ◽  
Budding Yeast ◽  
Microtubule Dynamics ◽  
Open Structure ◽  
Microtubule Associated Proteins ◽  
Associated Proteins ◽  
The Common

Stu2p from budding yeast belongs to the conserved Dis1/XMAP215 family of microtubule-associated proteins (MAPs). The common feature of proteins in this family is the presence of HEAT repeat–containing TOG domains near the NH2 terminus. We have investigated the functions of the two TOG domains of Stu2p in vivo and in vitro. Our data suggest that Stu2p regulates microtubule dynamics through two separate activities. First, Stu2p binds to a single free tubulin heterodimer through its first TOG domain. A large conformational transition in homodimeric Stu2p from an open structure to a closed one accompanies the capture of a single free tubulin heterodimer. Second, Stu2p has the capacity to associate directly with microtubule ends, at least in part, through its second TOG domain. These two properties lead to the stabilization of microtubules in vivo, perhaps by the loading of tubulin dimers at microtubule ends. We suggest that this mechanism of microtubule regulation is a conserved feature of the Dis1/XMAP215 family of MAPs.

scholarly journals Whither Magnetic Hyperthermia? A Tentative Roadmap

Materials ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 706
Author(s):  
Irene Rubia-Rodríguez ◽  
Antonio Santana-Otero ◽  
Simo Spassov ◽  
Etelka Tombácz ◽  
Christer Johansson ◽  
...  
Keyword(s):  
Clinical Trials ◽  
Nanoparticle Synthesis ◽  
Careful Analysis ◽  
Magnetic Hyperthermia ◽  
Lessons Learned ◽  
In Vivo Testing ◽  
Evolution Of Science ◽  
Made In ◽  
Critical Aspects

The scientific community has made great efforts in advancing magnetic hyperthermia for the last two decades after going through a sizeable research lapse from its establishment. All the progress made in various topics ranging from nanoparticle synthesis to biocompatibilization and in vivo testing have been seeking to push the forefront towards some new clinical trials. As many, they did not go at the expected pace. Today, fruitful international cooperation and the wisdom gain after a careful analysis of the lessons learned from seminal clinical trials allow us to have a future with better guarantees for a more definitive takeoff of this genuine nanotherapy against cancer. Deliberately giving prominence to a number of critical aspects, this opinion review offers a blend of state-of-the-art hints and glimpses into the future of the therapy, considering the expected evolution of science and technology behind magnetic hyperthermia.

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