Feasibility of Standardized Ejecta Evaluation for Spacecraft Surface Materials

Although a large spacecraft such as the International Space Station and other artificial satellites are thriving in the space environment due to the remarkable progress in the space development sector, their collisions with space debris are a growing concern. To examine the impact proof performance of spacecraft to space debris, hypervelocity impact experiments using a two-stage light gas gun and so on are necessary. However, space debris impact experiments are conducted in different manners dependent on the countries and the facilities. Therefore direct comparisons of the experimental results among different facilities are often difficult from the same viewpoint. In this study, the authors aim at assessment of international standardization of the hypervelocity impact experiments procedure. Projectiles with a diameter of 1 mm were used to simulate space debris impacting a target at 5 km/s. Copper witness plates were used to catch the secondary debris, namely ejecta, generated during the experiments. The size distributions of diameter of craters made by ejecta were measured on the witness plates, and they are compared one another among a solar array coupon, CFRP honeycomb and Aluminum honeycomb.2012 Hypervelocity Impact Symposium (HVIS 2012), September 16-20, 2012, Baltimore, Marylan

Non-Steroidal Anti-Inflammatory Drugs and Cognitive Function: Are Prostaglandins at the Heart of Cognitive Impairment in Dementia and Delirium ?

Studies of non-steroidal anti-inflammatory drugs (NSAIDs) in rheumatoid arthritis imply that inflammation is important in the development of Alzheimer’s disease (AD). However, these drugs have not alleviated the symptoms of AD in those who have already developed dementia. This suggests that the primary mediator targeted by these drugs, PGE2, is not actively suppressing memory function in AD. Amyloid-β oligomers appear to be important for the mild cognitive changes seen in AD transgenic mice, yet amyloid immunotherapy has also proven unsuccessful in clinical trials. Collectively, these findings indicate that NSAIDs may target a prodromal process in mice that has already passed in those diagnosed with AD, and that synaptic and neuronal loss are key determinants of cognitive dysfunction in AD. While the role of inflammation has not yet become clear, inflammatory processes definitely have a negative impact on cognitive function during episodes of delirium during dementia. Delirium is an acute and profound impairment of cognitive function frequently occurring in aged and demented patients exposed to systemic inflammatory insults, which is now recognised to contribute to long-term cognitive decline. Recent work in animal models is beginning to shed light on the interactions between systemic inflammation and CNS pathology in these acute exacerbations of dementia. This review will assess the role of prostaglandin synthesis in the memory impairments observed in dementia and delirium and will examine the relative contribution of amyloid, synaptic and neuronal loss. We will also discuss how understanding the role of inflammatory mediators in delirious episodes will have major implications for ameliorating the rate of decline in the demented population