The association of heat shock protein genetic polymorphisms with age-related hearing impairment in Taiwan

Background Age-related hearing impairment (ARHI) is a major disability among the elderly population. Heat shock proteins (HSPs) were found to be associated with ARHI in animal studies. The aim of this study was to analyze the associations of single nucleotide polymorphisms (SNPs) of HSP genes with ARHI in an elderly population in Taiwan. Methods Participants ≥65 years of age were recruited for audiometric tests and genetic analyses. The pure tone average (PTA) of the better hearing ear was calculated for ARHI evaluation. The associations of HSPA1L (rs2075800 and rs2227956), HSPA1A (rs1043618) and HSPA1B (rs2763979) with ARHI were analyzed in 146 ARHI-susceptible (cases) and 146 ARHI-resistant (controls) participants. Results The “T” allele of HSPA1B rs2763979 showed a decreased risk of ARHI. The “TT” genotype of rs2763979 also showed a decreased risk of ARHI in the dominant hereditary model. For HSPA1L (rs2075800 and rs2227956) and HSPA1A (rs1043618), the haplotype “CAG” was related to a decreased risk of ARHI. Conclusion These findings suggest that HSP70 polymorphisms are associated with susceptibility to ARHI in the elderly population. Graphical abstract

Modelling of mined rock thin layer disintegration taking into consideration its properties changing during compaction

The aim of the work is modelling of stressed condition of the loose mined rock thin layer between two parallel working plates of disintegrator, taking into consideration the dependences of the layer porosity and its side thrust coefficient on the main stress value with hereditary model of deformation accumulation. The equation of extreme balance of mined rock compactable thin layer is obtained for the case of its compression with partial sliding on working surfaces. It is shown, that there is no sliding in the central area of deformed zone, unlike the peripheral area. The iterative algorithm for parameters calculation of the layer stressed condition for the hypothesis of symmetric parabolic distribution of the axial normal stresses in the directions being perpendicular to the plates is developed. The distributions of the side thrust coefficient in the layer, the effective coefficient of external friction and the stresses of disintegrators working surfaces are grounded. The practical value of the research is the possibility to determine precisely the contact forces while crushing of fine-grained material taking into consideration its compactibility.

Influence of Nonviscous Damping on Seismic Inelastic Displacements

Viscous damping, which assumes a resisting force proportional to the instantaneous velocity, results in energy dissipation that increases linearly with frequency. Such energy dissipation, however, is not strongly supported by experiments. The energy dissipative characteristics of damping can be improved by nonviscous hereditary model, where the damping force is treated as dependent on the response history. A weighting function with built-in exponential decay can be used to represent the fading memory of damping where the recent history is given a greater influence over its distant past. This paper investigates the seismic response of structures using exponentially decaying nonviscous damping and compares the response with that of classical viscous damping. Preliminary results show an increase in inelastic displacements in the exponential damping model for both normal and near-fault ground motions. As part of the study, system characteristics of the exponential damping model are investigated.