The tripole vortex: Experimental evidence and explicit solutions.

Based on experimental evidence, explicit vorticity-distributed solutions to the Euler equations in two dimensions are constructed describing the tripole vortex. The vortex form and the solution outside the region of nonzero vorticity are derived analytically, while the interior is solved numerically. The continuous-vorticity solution reproduces the main features of the tripoles observed in laboratory experiments and numerical simulations-their shape, flow pattern, and the form of the nonlinear vorticity vs streamfunction relation.

Transient evoked otoacoustic emissions in laboratory animals.

Transient evoked otoacoustic emissions (TEOAEs) are much used clinically. However, it has been difficult to record them in small laboratory animals, and experimental manipulations designed to determine the generation mechanisms of this type of emission could not be performed. After refining the technique, based on the use of short clicks and a short amplifier gain suppression period, TEOAEs were recorded using the same instrumentation and techniques in rabbits, Psammomys obesus (fat sand rats), mice, rats and guinea pigs.

Effect of long-term noise exposure on the developing and developed ear in the Rat.

There have been reports that the developing ear is more sensitive than the adult ear to noise-induced hearing loss. This was investigated by testing auditory function in rats, both electrophysiologically and histologically, following exposure to broad-band noise (12 h/day for 15 days) at different stages of auditory development (neonates and adults), and also in age-matched controls. An exposure of 90 dB SPL broad-band noise caused no long-term change in auditory function in either age group.

Effect of temperature on the transient evoked and distortion product otoacoustic emissions in rats.

In order to study the energy dependence of the cochlear amplifier, transient evoked otoacoustic emissions (TEOAEs) and distortion product otoacoustic emissions (DPOAEs) were recorded in rats during gradual cooling to 27 degrees C and heating to 40 degrees C. In the range 33-39 degrees C, the TEOAEs and DPOAEs were maximal in amplitude and almost insensitive to temperature. However, they were significantly depressed (reversibly) at higher and lower temperatures.

Development of transient evoked otoacoustic emissions in the neonatal rat.

Otoacoustic emissions (OAEs) represent acoustic energy generated by the cochlear amplifier which contributes to auditory sensitivity and frequency discrimination. Therefore the OAEs can serve as a noninvasive tool to study the cochlear amplifier. While transient evoked OAEs (TEOAEs) are generally recorded clinically in man, it has been difficult to record them in animals and instead cubic distortion product OAEs (DPOAEs) have been experimentally studied in animals.

Cooling induces a decrease in middle ear compliance.

The effects of cooling rats from 37 degrees C to 27 degrees C and rewarming to 37 degrees C on the conductive mechanism of the middle ear was studied by means of acoustic impedance measurements. Cooling reduced middle ear compliance reversibly, without an effect on external canal volume and middle ear pressure. These results provide evidence for an increase in the stiffness of the tympanic membrane and/or of the ossicular chain and/or a decrease in stapes mobility.

Transient evoked otoacoustic emissions can be recorded in the rat.

Transient (click) evoked (TEOAE) and distortion product (DPOAE) otoacoustic emissions can be recorded in most normal human ears. Even though DPOAEs have been recorded in many laboratory animals, there has not been much success in recording TEOAEs in non-primate mammals except for guinea pigs. In this study, TEOAEs were unequivocally recorded in every rat (and guinea pig) ear studied by using short pulses (40 microseconds) to generate the clicks and a short (1.

Comparison of the efficiency of various criteria for artifact rejection in the recording of auditory brain-stem responses (ABR).

Artifact rejection using various criteria has not yet been investigated comparatively in the determination of auditory brain-stem responses (ABR). The aim of this paper is to test the efficiency of three different criteria of artifact rejection: the 'level' criterion, the 'amplitude histogram' criterion, and the 'power' criterion, and to compare their practical applicability. With regard to the identification of the single waves of ABR (percentage frequency of their appearance) and their amplitudes without and with artifact rejection, it can be shown that the frequency of appearance increases severalfold when one of the artifact rejection criteria is used.