IDENTIFICATION OF NONLINEAR BEHAVIOR IN A COMPOSITE STRUCTURE WITH CORE-CRUSHING DAMAGE

ABSTRACT Many damage detection methods that are applied to composite structures rely on nonlinear features in the dynami

Astrocyte-mediated short-term synaptic depression in the rat hippocampal CA1 area: two modes of decreasing release probability

<p>Abstract</p> <p>Background</p> <p>Synaptic burst activation feeds back as a short-term depression of release probability at hippocampal CA3-CA1 synapses. This short-term synaptic plasticity requires functional astrocytes and it affects both the recently active (< 1 s) synapses (post-burst depression) as well as inactive neighboring synapses (transient heterosynaptic depression). The aim of this study was to investigate and compare the components contributing to the depression of release probability in these two different scenarios.</p> <p>Results</p> <p>When tested using paired-pulses, following a period of inactivity, the transient heterosynaptic depression was expressed as a reduction in the response to only the first pulse, whereas the response to the second pulse was unaffected. This selective depression of only the first response in a high-frequency burst was shared by the homosynaptic post-burst depression, but it was partially counteracted by augmentation at these recently active synapses. In addition, the expression of the homosynaptic post-burst depression included an astrocyte-mediated reduction of the pool of release-ready primed vesicles.</p> <p>Conclusions</p> <p>Our results suggest that activated astrocytes depress the release probability via two different mechanisms; by depression of vesicular release probability only at inactive synapses and by imposing a delay in the recovery of the primed pool of vesicles following depletion. These mechanisms restrict the expression of the astrocyte-mediated depression to temporal windows that are typical for synaptic burst activity.</p

Design, Build and Validation of a Small-Scale Combustion Chamber Testing Facility

This study investigated the design parameters necessary for the construction and use of a testing facility built to test the combustor section of engines. User inputs were acquired by interview and used in the decisions made in arrangement of pieces of machinery and how different systems were to interact. The design was then carried out as the various parts of the facility were built and installed. Software was designed which controlled the different parts of the combustion process and monitored the different products of combustion as well as the properties of the air and fuel used in the combustion. These measurements were analyzed to determine the efficiency of combustion in the combustor. All systems and measurements were conducted and operated while following the guidance set forth in SAE ARP 1256. Safeguard systems were also designed into the facility to maintain a safe work environment for the user. These safeguards include automatic fuel shut-offs, heater shut-offs, and general system power downs. While the system was originally designed to handle the testing of a planar 2-D combustion chamber, the labs now have the capability to analyze any type of system that requires a combustion analyzer that follows SAE ARP 1256, a system that requires heated air or fuel, a system that requires an exhaust system to pull gasses out of the testing area, or a system that needs open flame. These additional capabilities allow further research to be conducted on site with an increase in ability to report different results