![]() 1984) have been found to respond to acoustic stimuli, often with good evidence that the vestibular afferents innervating the sacculus are the most acoustically sensitive. 1983 Didier and Cazals 1989), and pigeons (Wit et al. The vestibular systems of birds and mammals including cats (McCue and Guinan 1994, 1995), monkeys (Young et al. It is clearly visible through the oval window once the stapes have been removed. In mice, for example, the sacculus is located behind the oval window membrane, directly in the line of vibration caused by movement of the stapes. Acoustic sensitivity of the sacculus in mammals might be expected as consequences of both its evolutionary history and anatomical location. There is further evidence that this stimulation may have behavioral significance (Todd 2001). 1982), have retained the ability to detect acoustic stimuli previously associated only with the cochlea. Recent studies have demonstrated, however, that parts of the mammalian vestibular system, notably the sacculus, historically one of the first acoustically sensitive organs (Popper et al. ![]() This sensitivity is achieved mainly by the cochlea, a relatively new evolutionary adaptation compared with the much more ancient vestibular system. Mammals have a remarkable sense of hearing, with auditory ranges specifically adapted to their particular acoustic niche. This last observation confirms that otoconial organs, most likely the sacculus, contribute to behavioral responses to low-frequency sounds in mice. However, masker enhancement was not observed in otoconia-absent Nox3 mice if the low-frequency masker tones were outside the sensitivity range of the cochlea. Masker-enhanced auditory startle responses were also observed in otoconia-absent Nox3 mice, which lack otoconia but have no obvious cochlea pathology. We show that the amplitude of an elicited auditory startle response is greater when the startle stimuli are presented simultaneously with a low-frequency masker, including masker tones that are outside the sensitivity range of the cochlea. Here we provide not only more evidence for the retained acoustic sensitivity of the sacculus, but we also found that acoustic stimulation of the sacculus has behavioral significance in mammals. Recent evidence from birds and mammals, including humans, has shown that the sacculus, a hearing organ in many lower vertebrates, has retained some of its ancestral acoustic sensitivity. Of these organs, the cochlea is involved in hearing, while the sacculus and utriculus serve to detect linear acceleration. Thermal aging models can describe longer explosion times by the loss of plasticizer-binder constituent which was more thermally reactive.The mammalian inner ear contains sense organs responsible for detecting sound, gravity and linear acceleration, and angular acceleration. Separate decomposition models were developed for HMX and the reactive PBX 9501 binder component (1:1 Estane:BDNPA/F) based on the measured explosion times. The thermal decomposition of these PBXs were modeled using a coupled thermal and heat transport code (chemical TOPAZ) using separate kinetics for HMX and binder decomposition. Analysis of the error in more ยป time measurement is limited and complicated by several experimental factors but the small time change appears to be experimentally significant. The data for aged PBX 9501 showed slightly longer explosion times at equivalent temperatures. New and aged LX-04 showed comparable decomposition kinetics. The times to explosion at different heating temperatures were compared to historical data on new LX-04 and PBX 9501 compounds to study any changes to their thermal stability. The tests involved heating 12.7 mm diameter spherical samples in pre-heated aluminum anvils until explosion. One-Dimensional-Time-To-Explosion (ODTX) experiments were conducted to study the thermal decomposition of aged LX-04, aged PBX 9501, HMX class 1 and class 2, Estane and Estane/BDNPA-F (PBX 950 1 plasticized-binder) materials.
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