Experimental investigation of flow characteristics of corrugated channel flow us ing PIV

The aim of the study is to determine the flow characteristics of corrugated duct. The whole study has been conducted for Reynolds numbers, Re=4000 and 6000. The corrugated duct geometry was designed for aspect ratios, s/H=0.3 and phase shift angle, ?=180°. Variations in flow characteristics of corrugated duct were investigated using the Particle Image velocimetry (PIV) technique. Time-averaged velocity distributions, patterns of streamline and corresponding turbulent statistics were determined. Augmentation of the Reynolds number leads to an increase in velocity due to the sharp corner edges of cavity. Dimensionless turbulent kinetic energy, contours indicate that the magnitude of turbulent kinetic energy, increases as a result of sharp corner edges of the cavities. High rate of momentum transfer is expected due to an increase of turbulence intensity

Acil Serviste Ateşli Silah Yaralanmalarının Analizi

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The relationship between serum sex steroid levels and heart rate variability parameters in males and the effect of age

PubMed: 21206198Objectives: We evaluated the relationships between sex steroid levels and heart rate variability (HRV) parameters. Study design: The study included 114 male subjects (mean age 46.6±11.3 years) presenting to our department for cardiologic evaluation. Hormonal analysis included serum levels of luteinizing hormone, prolactin, total testosterone (TT), free testosterone, estradiol (E2), and dehydroepiandrosterone sulfate (DHEA-S). Parameters of HRV were derived from 24-hour Holter monitoring. The associations between serum sex steroid levels and HRV parameters were investigated in three age groups (20-39 years; 40-59 years; >60 years). Results: All the participants had normal biochemical results. The three age groups were similar in terms of anthropometric measurements. Among sex steroids analyzed, only serum DHEA-S level was significantly different among the groups (p=0.026), showing a decreasing trend with age. In the evaluation of HRV, all parasympathetic activities decreased (for HFn, pNN50, and rMSDD: p=0.001, p=0.000, and p=0.000, respectively), while only LF/HF among sympathetic activities increased (p=0.000) with age. Partial correlation analysis with control of age and waist circumference showed that TT and DHEA-S were positively correlated with HF n (parasympathetic parameter), and were in negative correlation with LF/HF24 hours and global sympathetic index (GSI) (sympathetic parameters). Serum E2 level was negatively correlated with the parasympathetic parameter of rMSSD, and positively correlated with LF/HF24 hours and GSI. Among serum sex steroids, DHEA-S was the most correlated parameter with autonomic functions. Conclusion: Our results showed positive correlations between androgens and parasympathetic activity and between estradiol and sympathetic activity in men, independent from anthropometric factors

Does evaluation of tumor volume or/both origination site better guide to optimal surgery for inverted papilloma?

Sinonasal inverted papilloma is noted for its high rate of recurrence. Staging systems aid to reduce recurrence and avoid excessive surgeries by guiding the selection of the optimal surgical approach