The Experts below are selected from a list of 4296 Experts worldwide ranked by ideXlab platform
Wen-jei Yang - One of the best experts on this subject based on the ideXlab platform.
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A computer simulation of the blood flow at the Aortic Bifurcation with flexible walls
Journal of biomechanical engineering, 1993Co-Authors: Zheng Lou, Wen-jei YangAbstract:To understand the role of fluid dynamics in atherogenesis, especially the effect of the flexibility of arteries, a two-dimensional numerical model for blood flow at the Aortic Bifurcation with linear viscoelastic walls is developed. The arbitrary Lagrangian-Eulerian method is adopted to deal with the moving boundary problem. The wall expansion induces flow reversals or eddies during the decelerating systole while the wall contraction restricts them during the diastole. A flexible Bifurcation experiences the shear stresses about 10 percent lower than those of a rigid one.
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A COMPUTER SIMULATION OF THE NON-NEWTONIAN BLOOD FLOW AT THE Aortic Bifurcation
Journal of biomechanics, 1993Co-Authors: Zheng Lou, Wen-jei YangAbstract:A two-dimensional numerical model was developed to determine the effect of the non-Newtonian behavior of blood on a pulsatile flow at the Aortic Bifurcation. The blood rheology was described by a weak-form Casson equation. The successive-over-relaxation (SOR) method was used to solve both the vorticity and Poisson equations numerically. It was disclosed that the non-Newtonian property of blood did not drastically change the flow patterns, but caused an appreciable increase in the shear stresses and a slightly higher resistance to both flow separations and the phase shifts between flow layers.
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A Computer Simulation of the Blood Flow at the Aortic Bifurcation with Flexible Walls
1991Co-Authors: Zheng Lou, Wen-jei YangAbstract:To understand the possible role of hemodynamics in the atherogenesis, especially the effect of the flexibility of the arteries, a two-dimensional numerical model for the blood flow at the Aortic Bifurcation with linear viscoelastic walls has been developed. The arbitrary Lagrangian-Eulerian method was used to deal with the moving boundaries. The successive-over-relaxation method was used to solve both the vorticity and Poisson equations. A flexible Bifurcation experienced the shear stresses about 10% lower than those by a rigid one.
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A computer simulation of the blood flow at the Aortic Bifurcation.
Bio-medical materials and engineering, 1991Co-Authors: Zheng Lou, Wen-jei YangAbstract:A two-dimensional finite-difference numerical model is developed for the blood flow at the Aortic Bifurcation to determine the possible role of fluid dynamics in the atherogenesis. Arterial walls are assumed to be rigid, while the fluid is Newtonian. Parametric studies are performed to evaluate the effects of the area ratio, Reynolds number, corner curvatures, Womersley number, Bifurcation angle and arterial pulsation on the flow and shear stresses. A high shear stress region exists on the inner wall distal to the vertex, while both high and low shear stress regions coexist along the outer wall. A temporary eddy is found along the outer wall, with more strength in the case of a higher area ratio. The results agree qualitatively with the existing experimental observations.
Zheng Lou - One of the best experts on this subject based on the ideXlab platform.
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A computer simulation of the blood flow at the Aortic Bifurcation with flexible walls
Journal of biomechanical engineering, 1993Co-Authors: Zheng Lou, Wen-jei YangAbstract:To understand the role of fluid dynamics in atherogenesis, especially the effect of the flexibility of arteries, a two-dimensional numerical model for blood flow at the Aortic Bifurcation with linear viscoelastic walls is developed. The arbitrary Lagrangian-Eulerian method is adopted to deal with the moving boundary problem. The wall expansion induces flow reversals or eddies during the decelerating systole while the wall contraction restricts them during the diastole. A flexible Bifurcation experiences the shear stresses about 10 percent lower than those of a rigid one.
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A COMPUTER SIMULATION OF THE NON-NEWTONIAN BLOOD FLOW AT THE Aortic Bifurcation
Journal of biomechanics, 1993Co-Authors: Zheng Lou, Wen-jei YangAbstract:A two-dimensional numerical model was developed to determine the effect of the non-Newtonian behavior of blood on a pulsatile flow at the Aortic Bifurcation. The blood rheology was described by a weak-form Casson equation. The successive-over-relaxation (SOR) method was used to solve both the vorticity and Poisson equations numerically. It was disclosed that the non-Newtonian property of blood did not drastically change the flow patterns, but caused an appreciable increase in the shear stresses and a slightly higher resistance to both flow separations and the phase shifts between flow layers.
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A Computer Simulation of the Blood Flow at the Aortic Bifurcation with Flexible Walls
1991Co-Authors: Zheng Lou, Wen-jei YangAbstract:To understand the possible role of hemodynamics in the atherogenesis, especially the effect of the flexibility of the arteries, a two-dimensional numerical model for the blood flow at the Aortic Bifurcation with linear viscoelastic walls has been developed. The arbitrary Lagrangian-Eulerian method was used to deal with the moving boundaries. The successive-over-relaxation method was used to solve both the vorticity and Poisson equations. A flexible Bifurcation experienced the shear stresses about 10% lower than those by a rigid one.
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A computer simulation of the blood flow at the Aortic Bifurcation.
Bio-medical materials and engineering, 1991Co-Authors: Zheng Lou, Wen-jei YangAbstract:A two-dimensional finite-difference numerical model is developed for the blood flow at the Aortic Bifurcation to determine the possible role of fluid dynamics in the atherogenesis. Arterial walls are assumed to be rigid, while the fluid is Newtonian. Parametric studies are performed to evaluate the effects of the area ratio, Reynolds number, corner curvatures, Womersley number, Bifurcation angle and arterial pulsation on the flow and shear stresses. A high shear stress region exists on the inner wall distal to the vertex, while both high and low shear stress regions coexist along the outer wall. A temporary eddy is found along the outer wall, with more strength in the case of a higher area ratio. The results agree qualitatively with the existing experimental observations.
Seok Hyun Kim - One of the best experts on this subject based on the ideXlab platform.
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vertical distance between umbilicus to Aortic Bifurcation on coronal view in korean women
Obstetrics & gynecology science, 2014Co-Authors: Joo Jeong, Yeo Rang Kim, Ju Yeong Kim, Byung Chul Jee, Seok Hyun KimAbstract:2 ) were also recorded. Results Aortic Bifurcation was located caudal to umbilicus in 52.9% and cephalad to umbilicus in 37.4%. The vertical distance had a negative relationship with BMI (r=−0.180, P=0.004), as well as woman's age (r=−0.382, P<0.001). However, a multivariate analysis revealed that the vertical distance had a significant negative relationship with woman's age (P<0.001) but not with BMI (P=0.510). An equation could be drawn to estimate the vertical distance by using woman's age and BMI: vertical distance (mm)=12.6−0.3×(age)−0.2×(BMI).
Michael L. Pearl - One of the best experts on this subject based on the ideXlab platform.
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The relationship of the umbilicus to the Aortic Bifurcation: implications for laparoscopic technique.
Obstetrics and gynecology, 1992Co-Authors: William W. Hurd, Ronald O. Bude, John O.l. Delancey, Michael L. PearlAbstract:Objective We evaluated the location of the umbilicus relative to the Aortic Bifurcation and the left common iliac vein where it crosses the midline. Methods Abdominal computed tomography images from 35 reproductive-age women were retrospectively reviewed to determine the location of the umbilicus. The results were correlated with body mass index using Pearson correlation coefficient and a two-tailed paired t test. Results The location of the umbilicus, but not the Aortic Bifurcation, was more caudal in heavier women and negatively correlated with body mass index. In nonobese women, the mean location of the umbilicus was 0.4 cm caudal to the Aortic Bifurcation, and was at or cephalad to the Bifurcation in eight of 15 (53%). In overweight women, the mean umbilical location was 2.4 cm caudal to the Bifurcation, and in obese women, 2.9 cm caudal to the Bifurcation. In the last two groups of subjects, the umbilicus was located at the level of the Bifurcation in six of 20 (30%). In every case, the umbilicus was located cephalad to where the common iliac vein crossed the midline. Conclusions The umbilicus is often located at or cephalad to the Aortic Bifurcation, and consistently located cephalad to where the left common iliac vein crosses the midline. The laparoscopic approach should take these relationships into account to minimize injuries to major retroperitoneal vessels.
Togas Tulandi - One of the best experts on this subject based on the ideXlab platform.
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anatomic relation between the umbilicus Aortic Bifurcation and transverse colon in males
Surgical technology international, 2010Co-Authors: Fawaz Alharbi, David Valenti, Ayman Altalib, Carolin Reinhold, Sarkis Meterissian, Togas TulandiAbstract:To examine the relationship between the umbilicus, major abdominal vessels, and transverse colon in males with differing body habitus, we conducted a prospective study including 91 male patients who underwent computerized tomography scan examinations. Of 91 males, 40 were normal weight, 27 overweight, and 24 obese. Compared with males of normal weight, the distance between the umbilicus and peritoneum was significantly greater in those who were overweight and obese. In males in whom the umbilicus was located cephalad to the Aortic Bifurcation, the distance was 1.4 to 2 cm. There was no significant difference in the distance among those who were normal weight, overweight, or obese. In males whose umbilicus was caudal to the Aortic Bifurcation, the distance in obese males (2.3±0.3 cm) was significantly greater than in those with normal weight (1.2±0.2 cm; P<0.01). Compared with normal weight males (8.6±0.7 cm), the distance between the umbilicus and transverse colon was significantly greater in the overweight males (10.7±0.7 cm, P: 0.02 CI -0.3 to -4.2) and obese males (11.5±1.0 cm, P: 0.01; CI-0.4 to -5.0). The location of the Aortic Bifurcation in relation to the umbilicus in men varies. However, generally the umbilicus is located caudal to the transverse colon.
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Location of Aortic Bifurcation and transverse colon in postmenopausal women: relevance to laparoscopy.
Surgical technology international, 2010Co-Authors: Ayman Al-talib, Fawaz Alharbi, David Valenti, Togas TulandiAbstract:This was a prospective study of postmenopausal women who underwent a computerized tomography (CT) examination of the abdomen and pelvis. We evaluated the location of the Aortic Bifurcation and transverse colon relative to the umbilicus at midline axis. Of 66 women, 24 were of normal weight, 23 were classified as overweight, and 19 as obese. The ages of the women in all groups were comparable. In the normal weight and overweight women, the mean location of the umbilicus was 0.6 cm +/- 0.4 cm and 0.4 cm +/- 0.3 cm cranial to the Aortic Bifurcation, respectively, and in obese women its mean location was 1.4 cm +/- 0.5 cm caudal to the Aortic Bifurcation. In approximately half of the normal weight and overweight women, the umbilicus was located cranial to the Aortic Bifurcation, and in 62.2% of obese women it was located caudal to the Aortic Bifurcation. Compared to those with normal weight (0.3 cm +/- 1.1 cm), the distance between umbilicus and transverse colon was greater in overweight (4.5 cm +/- 1.2 cm) and obese women (7.1 cm +/- 0.7 cm). In approximately one third of the normal weight women and over half of the overweight women, the umbilicus was located caudal to the transverse colon. In contrast, the umbilicus in 84.2% of the obese women was located caudal to transverse colon. There was a linear correlation between the distance of umbilicus and transverse colon distance and body mass index (BMI; r = 0.54, p < 0.0001). Regardless of the BMI, there was a wide variability whether the umbilicus was cranial or caudal to the Aortic Bifurcation or transverse colon. Similar to that in reproductive-aged women, in postmenopausal women the location of the Aortic Bifurcation and transverse colon varies. Proper insertion of the Veress needle and trocar is more important than a particular angle of insertion.
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Anatomic relation between the umbilicus, Aortic Bifurcation, and transverse colon in males.
Surgical technology international, 2010Co-Authors: Fawaz Alharbi, Ayman Al-talib, David Valenti, Carolin Reinhold, Sarkis Meterissian, Togas TulandiAbstract:To examine the relationship between the umbilicus, major abdominal vessels, and transverse colon in males with differing body habitus, we conducted a prospective study including 91 male patients who underwent computerized tomography scan examinations. Of 91 males, 40 were normal weight, 27 overweight, and 24 obese. Compared with males of normal weight, the distance between the umbilicus and peritoneum was significantly greater in those who were overweight and obese. In males in whom the umbilicus was located cephalad to the Aortic Bifurcation, the distance was 1.4 to 2 cm. There was no significant difference in the distance among those who were normal weight, overweight, or obese. In males whose umbilicus was caudal to the Aortic Bifurcation, the distance in obese males (2.3±0.3 cm) was significantly greater than in those with normal weight (1.2±0.2 cm; P
