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S Sjoerd W Rienstra - One of the best experts on this subject based on the ideXlab platform.
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sound propagation in slowly varying lined flow Ducts of arbitrary Cross section
Journal of Fluid Mechanics, 2003Co-Authors: S Sjoerd W RienstraAbstract:Sound transmission through Ducts of constant Cross-section with a uniform inviscid mean flow and a constant acoustic lining (impedance wall) is classically described by a modal expansion, where the modes are eigenfunctions of the corresponding Laplace eigenvalue problem along a Duct Cross-section. A natural extension for Ducts with Cross-section and wall impedance that are varying slowly (compared to a typical acoustic wavelength and a typical Duct radius) in the axial direction is a multiple-scales solution. This has been done for the simpler problem of circular Ducts with homentropic irrotational flow. In the present paper, this solution is generalized to the problem of Ducts of arbitrary Cross-section. It is shown that the multiple-scales problem allows an exact solution, given the Cross-sectional Laplace eigensolutions. The formulation includes both hollow and annular geometries. In addition, the turning point analysis is given for a single hard-wall cut-on, cut-off transition. This appears to yield the same reflection and transmission coefficients as in the circular Duct problem.
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sound propagation in slowly varying lined flow Ducts of arbitrary Cross section
RANA : reports on applied and numerical analysis, 2002Co-Authors: S Sjoerd W RienstraAbstract:Sound transmission through Ducts of constant Cross section with a uniform inviscid mean flow and a constant acoustic lining (impedance wall) is classically described by a modal expansion, where the modes are eigenfunctions of the corresponding Laplace eigenvalue problem along a Duct Cross section. A natural extension for Ducts with Cross section and wall impedance that are varying slowly (compared to a typical acoustic wave length and a typical Duct radius) in axial direction is a multiple-scales solution. This was previously done for the simpler problem of circular Ducts with homentropic irrotational flow. In the present paper, this solution is generalised to the problem of Ducts of arbitrary Cross section. It is shown that the multiple-scales problem allows an exact solution, given the Cross sectional Laplace eigensolutions. The formulation includes both hollow and annular type of geometries. In addition, the turning point analysis is given for a single hard wall cut-on, cut-off transition. This appears to yield the same reflection and transmission coefficients as in the circular Duct problem.
Yan Gao Man - One of the best experts on this subject based on the ideXlab platform.
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mammary Ducts with and without focal myoepithelial cell layer disruptions show a different frequency of white blood cell infiltration and growth pattern implications for tumor progression and invasion
Applied Immunohistochemistry & Molecular Morphology, 2005Co-Authors: Morvarid Yousefi, Rubina Mattu, Chunling Gao, Yan Gao ManAbstract:The authors' previous studies revealed that a subset of Ductal carcinoma in situ (DCIS) contained focally disrupted myoepithelial (ME) cell layers and basement membrane (BM). As the disruption of these two structures is a prerequisite for tumor invasion, and white blood cells (WBCs) contain digestive enzymes capable of degrading both the BM and damaged host cells, this study was designed to assess the possible roles of WBC in ME cell layer disruptions and tumor invasion. A total of 23 DCIS containing Ducts with focally disrupted ME cell layers were selected from 94 such cases identified in the authors' previous studies. Two consecutive sections from each case were double immunostained, one with leukocyte common antigen (LCA) plus smooth muscle actin (SMA) and the other with Ki-67 plus SMA. Ducts lined by at least 50 epithelial cells and distinct ME cell layers were examined. A total of 191 Duct Cross-sections were found to contain focal ME cell layer disruptions; of these, 186 (97.4%) were with and 5 (2.6%) were without WBC infiltration. Of 207 morphologically similar sections without ME disruptions, 46 (22.2%) were with and 161 (77.8%) were without WBC infiltration. Ki-67-positive cells in Ducts with focally disrupted ME cell layers were generally subjacent to ME cell layers, and more than 30 clusters of multiple proliferating cells were seen directly overlying or near focally disrupted ME cell layers. In contrast, Ki-67-positive cells in Ducts without ME disruptions were scattered over the entire epithelial compartment. The significantly different frequency of WBC infiltration and clusters of multiple proliferating cells in Ducts with and without ME disruptions suggests that WBCs might play important roles in ME disruption and tumor invasion.
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cell clusters overlying focally disrupted mammary myoepithelial cell layers and adjacent cells within the same Duct display different immunohistochemical and genetic features implications for tumor progression and invasion
Breast Cancer Research, 2003Co-Authors: Yan Gao Man, Lisa Tai, Ross Barner, Russell Vang, Jeffrey S Saenger, Kris M Shekitka, Gary L Bratthauer, Darren T Wheeler, Chang Y Liang, Tuyethoa N VinhAbstract:Our previous studies detected focal disruptions in myoepithelial cell layers of several Ducts with carcinoma in situ. The cell cluster overlying each of the myoepithelial disruptions showed a marked reDuction in or a total loss of immunoreactivity for the estrogen receptor (ER). This is in contrast to the adjacent cells within the same Duct, which were strongly immunoreactive for the ER. The current study attempts to confirm and expand previous observations on a larger scale. Paraffin sections from 220 patients with ER-positive intraDuctal breast tumors were double immunostained with the same protocol previously used. Cross-sections of Ducts lined by ≥ 40 epithelial cells were examined for myoepithelial cell layer disruptions and for ER expression. In five selected cases, ER-negative cells overlying the disrupted myoepithelial cell layer and adjacent ER-positive cells within the same Duct were separately microdissected and assessed for loss of heterozygosity and microsatellite instability. Of the 220 cases with 5698 Duct Cross-sections examined, 94 showed disrupted myoepithelial cell layers with 405 focal disruptions. Of the 94 cases, 79 (84%) contained only ER-negative cell clusters, nine (9.6%) contained both ER-negative and ER-positive cell clusters, and six (6.4%) contained only ER-positive cell clusters overlying disrupted myoepithelial cell layers. Of the 405 disruptions, 350 (86.4%) were overlain by ER-negative cell clusters and 55 (13.6%) were overlain by ER-positive cell clusters (P < 0.01). Microdissected ER-negative and ER-positive cells within the same Duct from all five selected cases displayed a different frequency or pattern of loss of heterozygosity and/or microsatellite instability at 10 of the 15 DNA markers. Cells overlying focally disrupted myoepithelial layers and their adjacent counterparts within the same Duct displayed different immunohistochemical and molecular features. These features potentially represent an early sign of the formation of a biologically more aggressive cell clone and the myoepithelial cell layer breakdown possibly associated with tumor progression or invasion.
Tuyethoa N Vinh - One of the best experts on this subject based on the ideXlab platform.
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cell clusters overlying focally disrupted mammary myoepithelial cell layers and adjacent cells within the same Duct display different immunohistochemical and genetic features implications for tumor progression and invasion
Breast Cancer Research, 2003Co-Authors: Yan Gao Man, Lisa Tai, Ross Barner, Russell Vang, Jeffrey S Saenger, Kris M Shekitka, Gary L Bratthauer, Darren T Wheeler, Chang Y Liang, Tuyethoa N VinhAbstract:Our previous studies detected focal disruptions in myoepithelial cell layers of several Ducts with carcinoma in situ. The cell cluster overlying each of the myoepithelial disruptions showed a marked reDuction in or a total loss of immunoreactivity for the estrogen receptor (ER). This is in contrast to the adjacent cells within the same Duct, which were strongly immunoreactive for the ER. The current study attempts to confirm and expand previous observations on a larger scale. Paraffin sections from 220 patients with ER-positive intraDuctal breast tumors were double immunostained with the same protocol previously used. Cross-sections of Ducts lined by ≥ 40 epithelial cells were examined for myoepithelial cell layer disruptions and for ER expression. In five selected cases, ER-negative cells overlying the disrupted myoepithelial cell layer and adjacent ER-positive cells within the same Duct were separately microdissected and assessed for loss of heterozygosity and microsatellite instability. Of the 220 cases with 5698 Duct Cross-sections examined, 94 showed disrupted myoepithelial cell layers with 405 focal disruptions. Of the 94 cases, 79 (84%) contained only ER-negative cell clusters, nine (9.6%) contained both ER-negative and ER-positive cell clusters, and six (6.4%) contained only ER-positive cell clusters overlying disrupted myoepithelial cell layers. Of the 405 disruptions, 350 (86.4%) were overlain by ER-negative cell clusters and 55 (13.6%) were overlain by ER-positive cell clusters (P < 0.01). Microdissected ER-negative and ER-positive cells within the same Duct from all five selected cases displayed a different frequency or pattern of loss of heterozygosity and/or microsatellite instability at 10 of the 15 DNA markers. Cells overlying focally disrupted myoepithelial layers and their adjacent counterparts within the same Duct displayed different immunohistochemical and molecular features. These features potentially represent an early sign of the formation of a biologically more aggressive cell clone and the myoepithelial cell layer breakdown possibly associated with tumor progression or invasion.
Sadanari Mochizuki - One of the best experts on this subject based on the ideXlab platform.
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effect of Cross sectional aspect ratio on turbulent heat transfer in an orthogonally rotating rectangular Duct with angled rib turbulators
International Journal of Heat and Mass Transfer, 2003Co-Authors: Akira Murata, Sadanari MochizukiAbstract:Abstract Heat transfer in a rotating rib-roughened rectangular Duct was numerically simulated by using the large eddy simulation with a Lagrangian dynamic subgrid-scale model. The rotation number and the Duct Cross-sectional aspect ratio (0.25, 0.5, 1.0, 2.0, and 4.0) were varied for a friction Reynolds number of 350 and rib angle of 60°. The present results clearly showed the locally high heat transfer at several locations and how it was changed by the Duct aspect ratio. The dissimilarity between the streamwise velocity and temperature was observed for all the aspect ratio cases in the rotating case.
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effect of Cross sectional aspect ratio on turbulent heat transfer in an orthogonally rotating rectangular smooth Duct
International Journal of Heat and Mass Transfer, 1999Co-Authors: Akira Murata, Sadanari MochizukiAbstract:Abstract In order to investigate the effects of the Coriolis force and the Duct Cross-sectional aspect ratio on turbulent heat transfer, the large eddy simulation was performed changing the aspect ratio and the rotation number in the range, 0.25–4.0 and 0–5.0, respectively, while the turbulent Reynolds number was 350. In the results, both direct and indirect influences of the Coriolis force on the turbulence were seen. The relative intensity of these influences depended on the aspect ratio. The Colburn’s j factor showed a higher value for a larger aspect ratio because of larger heat transfer enhancement on the pressure and side surfaces.
Surya Pratap Vanka - One of the best experts on this subject based on the ideXlab platform.
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preferential concentration of particles in a fully developed turbulent square Duct flow
International Journal of Multiphase Flow, 2004Co-Authors: Chad Winkler, Sarma L Rani, Surya Pratap VankaAbstract:Abstract The preferential concentration of dense particles in a downward, fully developed turbulent square Duct flow at Reτ=360, based on mean friction velocity and Duct width, is studied using large eddy simulations. Due to the low volume fractions involved (maximum volume fraction To demonstrate preferential concentration, variation of vorticity magnitude, swirling strength, maximum compressional strain-rate, and ∇ u : ∇ u , and their probability distribution functions (PDF) conditioned on particle presence, with particle response time is presented. Since the square Duct Cross-section is inhomogeneous, we also study variation in preferential concentration with Cross-sectional location. Particles are seen to accumulate in regions of high ∇ u : ∇ u and strain-rate and in regions of low swirling strength. In general, particles accumulate in regions of low vorticity magnitude. However, near the wall, the tendency of particles to accumulate in regions of high vorticity increases with response time.
