[Distribution and drug resistance analysis of secretion pathogens in 90 children with acute otitis media].

Objective:To analyze the pathogenic bacteria distribution and drug resistance of secretion in 90 child patients with acute otitis media. Method:The clinical data of 90 cases of acute otitis media child patients were retrospectively analyzed. The distribution of pathogenic bacteria in all child patients were analyzed. The child patients were divided into A group（less than 1 year old, n=38）, B group （1 to 3 years old, n=27） and C group （more than 3 years old, n=25） according to the age. The streptococcus pneumoniae detection in each group and the streptococcus pneumoniae resistant to various antibacterial agents were compared. Result:The positive rate of pathogen detection in children was 75.6% （68/90）, and the highest proportion was streptococcus pneumoniae with 61.8% （42/68）. The detection rate of streptococcus pneumoniae in A and B group was significantly higher than that of C group （P<0.05）. The resistance rate of streptococcus pneumoniae to different antibacterial drugs is quite different. Conclusion:Streptococcus pneumoniae is the main pathogenic bacterium in child patients with acute otitis media less than 3 years old, and different types of antibacterial drugs have different drug resistance.

Analytical approach for sound attenuation in perforated dissipative silencers with inlet/outlet extensions.

The acoustic attenuation performance of perforated dissipative circular expansion chambers with inlet/outlet extensions is investigated. The eigenvalues and eigenfunctions of the sound field are analytically determined in the extended inlet/outlet circular ducts, upstream/downstream end annular dissipative chambers, and the central perforated dissipative expansion chamber. Utilizing the continuity conditions of velocity/pressure at the interfaces the transmission loss is predicted by a two-dimensional analytical approach. For a specific configuration, such predictions are compared with both experiments and a three-dimensional computational solution based on the substructure boundary element technique, showing a reasonable agreement. The analytical results for the effect of the absorbent resistivity, duct porosity, and geometryon the acoustic attenuation performance are discussed in detail.

Helmholtz resonator lined with absorbing material.

A closed-form, two-dimensional analytical solution is developed to investigate the acoustic performance of a concentric circular Helmholtz resonator lined with fibrous material. The effect of density and the thickness of the fibrous material in the cavity is examined on the resonance frequency and the transmission loss. With the expressions for the eigenvalue and eigenfunction in the cavity, the transmission loss is obtained for a piston-driven model by applying a pressure/velocity matching technique. The results from the analytical methods are compared to the numerical predictions from a three-dimensional boundary element method and the experimental data obtained from an impedance tube setup. It is shown that the acoustic performance of a Helmholtz resonator may be modified considerably by the density and thickness of the fibrous material without changing the cavity dimensions.