Thermally Induced Micromechanical Stresses in Ceramic/Ceramic Composites

The internal micromechanical stresses which develop in ceramic-ceramic composites as a consequence of temperature changes and thermoelastic property differences between the reinforcing and matrix phases are addressed by the Eshelby method. Results for two whisker reinforced ceramic matrix composites and for quartz particles in porcelain are discussed. It is concluded that the stresses which develop in the second phase reinforcing inclusions are quite substantial (GPa-levels) and may be highly anisotropic in character. These stresses are additive to the macroscopic thermal stresses from temperature gradients which are encountered during heating and cooling, and also to externally apphed mechanical stresses (loads). These micromechanical stresses are expected to be highly significant for thermal cycling fatigue and other failure processes

Impact of parental history of substance use disorders on the clinical course of anxiety disorders

<p>Abstract</p> <p>Background</p> <p>Among the psychological difficulties seen in children of parents with substance use problems, the anxiety disorders are among the most chronic conditions. Although children of alcoholic parents often struggle with the effects of parental substance use problems long into adulthood, empirical investigations of the influence of parental substance use disorders on the course of anxiety disorders in adult offspring are rare. The purpose of this study was to examine prospectively the relationship between parental substance use disorders and the course of anxiety disorders in adulthood over the course of 12 years.</p> <p>Methods</p> <p>Data on 618 subjects were derived from the Harvard/Brown Anxiety Research Project (HARP), a longitudinal naturalistic investigation of the clinical course of multiple anxiety disorders. Kaplan-Meier survival estimates were used to calculate probabilities of time to anxiety disorder remission and relapse. Proportional hazards regressions were conducted to determine whether the likelihood of remission and relapse for specific anxiety disorders was lower for those who had a history of parental substance use disorders than for individuals without this parental history.</p> <p>Results</p> <p>Adults with a history of parental substance use disorders were significantly more likely to be divorced and to have a high school level of education. History of parental substance use disorder was a significant predictor of relapse of social phobia and panic disorders.</p> <p>Conclusion</p> <p>These findings provide compelling evidence that adult children of parents with substance use disorders are more likely to have relapses of social phobia and panic disorders. Clinicians who treat adults with anxiety disorders should assess parental substance use disorders and dependence histories. Such information may facilitate treatment planning with regards to their patients' level of vulnerability to perceive scrutiny by others in social situations, and ability to maintain a long-term panic-free state.</p

Ionospheric Response to Natural and Man Made Impacts

International audienceThe problem of energy transfer from the Earth’s solid mantles to the atmosphere and surrounding space is of essential importance for the fundamental geophysics and applied studies. These processes can largely govern the structure and dynamics of the phenomena developing in the near Earth space. Moreover, the consequences of such impacts as earthquakes, hurricanes, etc. upon the Earth’s electromagnetic field and ionosphere can become an extra factor in monitoring the processes involved in the upcoming large-scale seismic and meteorological catastrophes. The acoustic-gravity waves (comprising acoustic and gravity waves and hereafter referred to as AGW) are one of the most efficient ways to transport over the ionosphere the energy of the dynamic processes developing in the low atmosphere. The early experiments of the 1950’s and 60’s on Doppler sounding even showed that the ionosphere can serve as a sensitive indicator of natural and man made disturbances. The Doppler sounding of the ionosphere revealed impulse and wave disturbances excited by powerful sources of infrasound, such as: a) megaton nuclear explosions in the atmosphere, kiloton ground industrial explosions, b) earthquakes and volcano eruptions, c) thunderstorms, tornadoes and tsunamis, d) bolides and meteorites, e) rocket launches and flights of supersonicjets, f) aurora and solar eclipse