Experimental Investigation of the Structure and Dynamics of Laminar Separation Bubbles

This work is an experimental investigation of the dynamics of the laminar separation bubbles, which are typically present on the suction side of lifting surfaces at a large angle of attack. The separation bubble was generated on a flat plate by an adverse pressure gradient induced by The adverse pressure gradient was generated by using an inverted wing with a NACA 643-618 airfoil mounted above the flat plate. Using Particle Image Velocimetry (PIV), a parametric study of the effect of the upstream flow velocity and the induced pressure gradient on the mean flow topology and the unsteady behavior of the separation bubble was carried out in the low-speed water tunnel of the Hydrodynamics Laboratory at the University of Arizona. The topology of the laminar separation bubble, and in particular the unsteady flow dynamics, were found to be strongly dependent on these parameters. For certain conditions, strong vortex shedding near the reattachment region of the bubble was observed, which is a characterisc behavior of short bubbles. High-resolution spatio-temporal PIV measurements were made to analyze the formation and breakdown of these flow structures. The frequency of vortex shedding was determined from Fourier analysis of the time series of the velocity fluctuations. The non-dimensionalised frequencies were found to be nearly independent of the Reynolds number for the range of Reynolds numbers investigated here.No embargo.This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]

Single nucleotide polymorphisms of the genes encoding IL-10 and TGF-β1 in Iranian children with atopic dermatitis

Background: Atopic dermatitis is an inflammatory skin disease in which both genetic and environmental factors interact to determine the susceptibility and severity of the disease. Objective: The aim of this study was to determine the association between atopic dermatitis and IL-10 and TGF-β1 gene polymorphisms. Methods: The allele and genotype frequencies of genes encoding for IL-10 and TGF-β1 were investigated in 89 patients with atopic dermatitis in comparison with 138 in the control group using the PCR-SSP method. Results: A significant increase was found in the frequency of the TGF-β1 codon 10/C allele among patients (p < 0.001, OR = 6.77), whereas a significant decrease was observed in the frequency of the T allele at the same position (p < 0.001, OR = 0.14). The frequency of the TGF-β1 codon 25/G allele in the control group was significantly higher than among patients (p < 0.001, OR = 0.08). A significant positive correlation was seen between CC (p < 0.001, OR = 15.10) and CG (p < 0.001) genotypes and AD at codons 10 and 25, respectively. The most frequent haplotypes among patients was TGF-β1 CG which was significantly higher than in the control subjects (50 in patients vs. 39.9 in controls, p = 0.042). A significant increase was found in the frequency of TGF-β CC (36 in patients vs. 7.6 in controls, p < 0.001) and TC (14 in patients vs. 0 in controls, p < 0.001) haplotypes among patients compared to controls. By contrast, the TGF-β1 TG haplotype was significantly lower in patients than controls (0 in patients vs. 52.5 in controls, p < 0.001). There were no significant differences in the frequency of alleles, genotypes and haplotypes of the IL-10 gene. Conclusions: We found a strong association between the polymorphisms of the TGF-β1 gene at codon 10 and codon 25 positions and atopic dermatitis. © 2017 SEICA

Single nucleotide polymorphisms of the genes encoding IL-10 and TGF-β1 in Iranian children with atopic dermatitis

Background: Atopic dermatitis is an inflammatory skin disease in which both genetic and environmental factors interact to determine the susceptibility and severity of the disease. Objective: The aim of this study was to determine the association between atopic dermatitis and IL-10 and TGF-β1 gene polymorphisms. Methods: The allele and genotype frequencies of genes encoding for IL-10 and TGF-β1 were investigated in 89 patients with atopic dermatitis in comparison with 138 in the control group using the PCR-SSP method. Results: A significant increase was found in the frequency of the TGF-β1 codon 10/C allele among patients (p < 0.001, OR = 6.77), whereas a significant decrease was observed in the frequency of the T allele at the same position (p < 0.001, OR = 0.14). The frequency of the TGF-β1 codon 25/G allele in the control group was significantly higher than among patients (p < 0.001, OR = 0.08). A significant positive correlation was seen between CC (p < 0.001, OR = 15.10) and CG (p < 0.001) genotypes and AD at codons 10 and 25, respectively. The most frequent haplotypes among patients was TGF-β1 CG which was significantly higher than in the control subjects (50 in patients vs. 39.9 in controls, p = 0.042). A significant increase was found in the frequency of TGF-β CC (36 in patients vs. 7.6 in controls, p < 0.001) and TC (14 in patients vs. 0 in controls, p < 0.001) haplotypes among patients compared to controls. By contrast, the TGF-β1 TG haplotype was significantly lower in patients than controls (0 in patients vs. 52.5 in controls, p < 0.001). There were no significant differences in the frequency of alleles, genotypes and haplotypes of the IL-10 gene. Conclusions: We found a strong association between the polymorphisms of the TGF-β1 gene at codon 10 and codon 25 positions and atopic dermatitis. © 2017 SEICA