Evaluation of Advanced Turbulence Models for High-Reynolds Number External Flow

In this report several modern turbulence modeling techniques with applications to high-Reynolds number external flow are critically evaluated. Fully developed turbulent channel flow and the flow past the Ahmed body with a slant angle of 25 degrees are both used to benchmark several LES and DES models for turbulence closure. Channel flow is simulated at two different Reynolds numbers and both the LES and DES approaches are found to exhibit predictive capabilities but with several limitations, especially at the higher Reynolds number. The flow past the Ahmed body is validated against several experimental measurements. The improved delayed detached eddy-simulation (IDDES) model is found to yield the best over-all drag prediction, but the wall-modeled LES approach is more robust across a wide range of grid resolutions. The computational effort required to perform the Ahmed-body simulations is summarized together with recommendations for the future use of the turbulence modeling techniques that are evaluated herein.http://deepblue.lib.umich.edu/bitstream/2027.42/110233/1/Report354.pdfDescription of Report354.pdf : Main Repor

Denture-related stomatitis is associated with endothelial dysfunction

Oral inflammation, such as periodontitis, can lead to endothelial dysfunction, accelerated atherosclerosis, and vascular dysfunction. The relationship between vascular dysfunction and other common forms of oral infections such as denture-related stomatitis (DRS) is unknown. Similar risk factors predispose to both conditions including smoking, diabetes, age, and obesity. Accordingly, we aimed to investigate endothelial function and major vascular disease risk factors in 44 consecutive patients with dentures with clinical and microbiological features of DRS (n = 20) and without DRS (n = 24). While there was a tendency for higher occurrence of diabetes and smoking, groups did not differ significantly in respect to major vascular disease risk factors. Groups did not differ in main ambulatory blood pressure, total cholesterol, or even CRP. Importantly, flow mediated dilatation (FMD) was significantly lower in DRS than in non-DRS subjects, while nitroglycerin induced vasorelaxation (NMD) or intima-media thickness (IMT) was similar. Interestingly, while triglyceride levels were normal in both groups, they were higher in DRS subjects, although they did not correlate with either FMD or NMD. Conclusions. Denture related stomatitis is associated with endothelial dysfunction in elderly patients with dentures. This is in part related to the fact that diabetes and smoking increase risk of both DRS and cardiovascular disease

High-Resolution Numerical Simulation of Turbulent Interfacial Marine Flows.

An important aspect of designing offshore structures and seagoing vessels is an accurate prediction of the loads associated with wave impacts. In regions near the shore or during storms at sea, breaking waves are a common occurrence and the loading caused by their impact is typically more severe than in the case of regular non-breaking waves. Present methods for numerically predicting the impact forces use potential-flow methods with empirically-derived coefficients or relatively low-order methods in the computational-fluid dynamics (CFD) family. The potential-flow methods usually cannot simulate wave breaking and thus correction factors are necessary to account for slamming-like impacts that may occur due to plunging breakers. In some applications of the CFD tools, turbulence models are used to approximate the turbulent wave-breaking process in an effort to improve the prediction of the flow. The present work expands the understanding of the turbulence-interface interaction using highly-resolved numerical simulations to improve the CFD modeling capabilities in marine applications. The complex behavior of turbulence in the proximity of a deformable interface separating two incompressible phases is studied using two variants of CFD: direct numerical simulations (DNS) and large-eddy simulations (LES) that require modeling of the turbulence closure terms. Canonical flows are studied with DNS to determine the influence of the information typically not resolved by lower-order CFD methods and to establish the hierarchy of the modeling terms present in the governing equations. The relative magnitude of the convective and the interfacial subgrid terms are found to be significant and thus not negligible for a plunging-breaking wave flow. A scale-similarity-based model is proposed and implemented in the LES solver to include the effects of the unresolved flow features associated with the presence of the interface. The model is found to successfully approximate the subgrid behavior in multiphase flows with sufficient spatial and temporal resolution. The multiphase LES framework is extended to the study of breaking waves impinging on an offshore platform and the importance of the subgrid modeling to an accurate prediction of forces on the structure in demonstrated.PhDNaval Architecture & Marine EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/102319/1/gfilip_1.pd

Mechanisms of oxidative stress in human aortic aneurysms — association with clinical risk factors for atherosclerosis and disease severity

Aortic abdominal aneurysms (AAA) are important causes of cardiovascular morbidity and mortality. Oxidative stress may link multiple mechanisms of AAA including vascular inflammation and increased metalloproteinase activity. However, the mechanisms of vascular free radical production remain unknown. Accordingly, we aimed to determine sources and molecular regulation of vascular superoxide (O2radical dot−) production in human AAA. Methods and results: AAA segments and matched non-dilated aortic samples were obtained from 40 subjects undergoing AAA repair. MDA levels (determined by HPLC/MS) were greater in plasma of AAA subjects (n = 16) than in risk factor matched controls (n = 16). Similarly, superoxide production, measured by lucigenin chemiluminescence and dihydroethidium fluorescence, was increased in aneurysmatic segments compared to non-dilated aortic specimens. NADPH oxidases and iNOS are the primary sources of O2radical dot− in AAA. Xanthine oxidase, mitochondrial oxidases and cyclooxygenase inhibition had minor or no effect. Protein kinase C inhibition had no effect on superoxide production in AAA. NADPH oxidase subunit mRNA levels for p22phox, nox2 and nox5 were significantly increased in AAAs while nox4 mRNA expression was lower. Superoxide production was higher in subjects with increased AAA repair risk Vanzetto score and was significantly associated with smoking, hypercholesterolemia and presence of CAD in AAA cohort. Basal superoxide production and NADPH oxidase activity were correlated to aneurysm size. Conclusions: Increased expression and activity of NADPH oxidases are important mechanisms underlying oxidative stress in human aortic abdominal aneurysm. Uncoupled iNOS may link oxidative stress to inflammation in AAA. Oxidative stress is related to aneurysm size and major clinical risk factors in AAA patients

The role of metalloproteinases in endometrial remodelling during menstrual cycle

Endometrium is the only tissue in the human body subject to cyclic transformations under the influence of ovarian steroid hormones. As estradiol and progesterone balance throughout the physiological menstrual cycle changes, so does the expression of metalloproteinases (MMPs). These endopeptides are responsible for keeping the balance between the process of synthesis and degradation of extracellular matrix proteins. Thus, MMP’s take part in sustaining physiological stability of the endometrium. A number of MMPs found in the endometrial tissue and their activity is related to menstrual cycle phase. This paper is an up-to-date review of literature of Medline database. The search was conducted for key words including “matrix metalloproteinases”, “MMPs”, “TIMPs” and “tissue inhibitors of metalloproteinases”. Over 1092 publications regarding interdependence and interplay between ovarian hormones and the role of various MMPs and their inhibitors in normal endometrial remodelling and in pathological conditions were analysed and critically reviewed

Markery proliferacji i inwazyjności w guzach przysadki wydzielających hormon wzrostu

Introduction In the search for markers of invasiveness of pituitary adenomas, we studied the expression of Ki-67 antigen, TOPO 2A (topoisomerase 2 alpha), AIP (Aryl Hydrocarbon Receptor-Interacting Protein) and VEGF (Vascular Endothelial Growth Factor) in somatotropinomas. Material and Methods We retrospectively studied a group of 31 patients who underwent pituitary tumour surgery. Expression of Ki-67, TOPO 2A, AIP and VEGF in surgical specimens was determined by immunohistochemistry. Relations between quantitatively determined markers and clinical symptoms, tumour features, and MR imaging, were analysed. Acromegaly was confirmed by hormonal tests in all patients studied. Local invasiveness (cavernous sinus penetration, optic chiasm compression or suprasellar extension) was observed in 18/31 patients (58,1%). Results Ki-67 was expressed in 77.4%, TOPO 2A in 87.1%, AIP in 83.8%, and VEGF in 87.1% of 31 cases of somatropinoma. Median values of Ki-67, TOPO 2A, AIP and cytoplasmic VEGF indices were 1.2% [IQR=2.2], 1.5% [IQR=1.6], 21.26% [IQR=20.1] and 20.4% [IQR=15.4], respectively. Ki-67, TOPO 2A, AIP and VEGF expression was not correlated with age nor with patient gender (p > 0.05). Only Ki-67 and TOPO 2A correlated with tumour size (for Ki-67: r=0.42, p=0.025; for TOPO 2A: r=0.53, p=0.003). Ki-67 and TOPO 2A levels were significantly higher in invasive compared to noninvasive somatropinomas (Ki67 mean values: 1.85±1.33% vs. 0.95±1.07%, p=0.024; TOPO 2A mean values: 2.19±1.63% vs. 1.45±1.23%, , p=0.011). Conclusions Ki-67, TOPO 2A, AIP and VEGF were expressed in over 70% of all somatotropinomas. Only Ki-67 and TOPO 2A expression correlated with tumour size and tumour invasiveness.Wstęp: W poszukiwaniu markerów inwazyjności gruczolaków przysadki badano ekspresję antygenu Ki-67, TOPO 2A (topoisomerase 2 alpha), AIP (Aryl Hydrocarbon Receptor-Interacting Protein) oraz VEGF (Vascular Endothelial Growth Factor) w guzach wydzielających hormon wzrostu. Materiał i metody: Badano retrospektywnie grupę 31 pacjentów, operowanych z powodu guza przysadki. Ekspresję Ki-67, TOPO 2A, AIP oraz VEGF badano immunohistochemicznie w tkankach uzyskanych chirurgicznie. Analizowano relacje między ilościową ekspresją markerów a objawami klinicznymi, cechami guza i obrazem MR. Testami hormonalnymi potwierdzono akromegalię u wszystkich badanych pacjentów. Miejscową inwazyjność, zdefiniowaną jako naciekanie zatoki jamistej, kompresję skrzyżowania wzrokowego, wzrost nadsiodłowy guza obserwowano u 18/31 (58,15) pacjentów. Wyniki: Ekspresję Ki-67 stwierdzono w 77,4%, TOPO 2A w 87,1%, AIP w 83,8%, oraz VEGF w 87,1% przypadków samatotropinoma (n = 31). Wartości median indeksów Ki-67, TOPO 2A, AIP i cytoplazmatycznego VEGF wynosiły 1,2% [IQR = 2,2], 1,5% [IQR = 1,6], 21,26% [IQR = 20,1] i 20,4% [IQR = 15,4], odpowiednio. Indeksy Ki-67, TOPO 2A, AIP i VEGF nie korelowały z wiekiem i płcią pacjentów (p > 0,05). Tylko Ki-67 i TOPO 2A korelowało z wielkością guza (dla Ki-67: r = 0,42, p = 0,025; dla TOPO 2A: r = 0,53, p = 0,003). Indeksy Ki-6 oraz TOPO 2A były znamiennie wyższe w guzach inwazyjnych w porównaniu z guzami nieinwazyjnymi (średnie Ki-67: 1,85 ± 1,33% vs 0,95 ± 1,07%, p = 0,024 oraz średnie TOPO 2A: 2,19 ± 1,63% vs 1,45 ± 1,23%, p = 0,011). Wnioski: Ekspresję Ki-67, TOPO 2A, AIP i VEGF stwierdzono w ponad 70% wszystkich somatotropinoma. Tylko ekspresja Ki-67 oraz TOPO 2A korelowała z wielkością guza i jego inwazyjnością