Finite element simulation of cochlear traveling wave under air and bone conduction hearing.

Besides the normal hearing pathway known as air conduction (AC), sound can also transmit to the cochlea through the skull, known as bone conduction (BC). During BC stimulation, the cochlear walls demonstrate rigid body motion (RBM) and compressional motion (CPM), both inducing the basilar membrane traveling wave (TW). Despite numerous measuring and modeling efforts for the TW phenomenon, the mechanism remains unclear, especially in the case of BC. This paper proposes a 3D finite element cochlea model mimicking the TW under BC. The model uses a traditional "box model" form, but in a spiral shape, with two fluid chambers separated by the long and flexible BM. The cochlear fluid was enclosed by bony walls, the oval and round window membranes. Contingent boundary conditions and stimulations are introduced according to the physical basis of AC and BC. Particularly for BC, both RBM and CPM of the cochlea walls are simulated. Harmonic numerical solutions are obtained at multiple frequencies among the hearing range. The BM vibration amplitude ([Formula: see text]) and its relation with volume displacement difference between the oval and round windows [Formula: see text], as well as the pressure difference at the base of the cochlea ([Formula: see text]), are analyzed. The simulated BM response at 12 mm from the base is peaked at about 3 k Hz, which is consistent with published experimental data. The TW properties under AC and BC are the same and have a common mechanism. (1) [Formula: see text] is proportional to [Formula: see text] at low frequencies. (2) [Formula: see text] is also proportional to [Formula: see text], within 5 dB error at high frequencies such as 16 k Hz. This study partly reveals the common quantitative relations between the TW and related factors under AC and BC hearing.

Characterization of Haemaphysalis flava (Acari: Ixodidae) from Qingling subspecies of giant panda (Ailuropoda melanoleuca qinlingensis) in Qinling Mountains (Central China) by morphology and molecular markers.

Tick is one of important ectoparasites capable of causing direct damage to their hosts and also acts as vectors of relevant infectious agents. In the present study, the taxa of 10 ticks, collected from Qinling giant pandas (Ailuropoda melanoleuca qinlingensis) in Qinling Mountains of China in April 2010, were determined using morphology and molecular markers (nucleotide ITS2 rDNA and mitochondrial 16S). Microscopic observation demonstrated that the morphological features of these ticks were similar to Haemaphysalis flava. Compared with other Haemaphysalis species, genetic variations between Haemaphysalis collected from A. m. qinlingensis and H. flava were the lowest in ITS2 rDNA and mitochondrial 16S, with sequence differences of 2.06%-2.40% and 1.30%-4.70%, respectively. Phylogenetic relationships showed that all the Haemaphysalis collected from A. m. qinlingensis were grouped with H. flava, further confirmed that the Haemaphysalis sp. is H. flava. This is the first report of ticks in giant panda by combining with morphology and molecular markers. This study also provided evidence that combining morphology and molecular tools provide a valuable and efficient tool for tick identification.