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A numerical simulation is carried out to investigate the effect of the Helmholtz resonator capacity on the Hartmann whistle operating at high values of the nozzle pressure ratio using the turbulence model. The results of the present numerical simulations are compared to experimental data. The simulation results show that the frequency and amplitude of the Hartmann whistle with the Helmholtz resonator are obviously lower as compared to the conventional Hartmann whistle. Moreover, the Mach number contours and streamlines indicate that the Helmholtz resonator does not affect the shock-cell structure between the nozzle and the cavity, and the Hartmann whistle with the Helmholtz resonator has a. jet regurgitant mode that is different from the Hartmann whistle with a. straight resonator. The diameter of the Helmholtz resonator is an important factor affecting the fundamental frequency. [ABSTRACT FROM AUTHOR]

Heat shock proteins (HSPs) are known as molecular chaperones, and they function in response to cell stress. HSPA13, also called STCH, is a member of the HSP70 family. In general, HSP70 family may play a protective role in prion diseases. In a recent study, the overexpression of HSPA13 was shown to shorten the incubation time of prion diseases. Although the exact role of HSPA13 in the pathogenesis of prion diseases remains unknown, the expression level of HSPA13 is significantly associated with the latent phase of prion diseases. It has been known that single nucleotide polymorphisms (SNPs) in promoter and open reading frame (ORF) region of genes can affect either gene expression or gene function. The purpose of this study was to investigate genotype and allele frequencies of SNPs found in the promoter and ORF of HSPA13 in healthy Korean population to obtain the information for subsequent population genetics and prion diseases studies. We observed four SNPs in the promoter region of HSPA13, of which two have previous identified (c.-608C>G; rs2242662 and c.-381G>A; rs2242661) and two are novel (c.-321C>T and c.-300A>G). Interestingly, we did not observe any polymorphisms in the ORF of this gene. To our knowledge, this is the first study of polymorphisms in the human HSPA13 gene. [ABSTRACT FROM AUTHOR]