Study of short-range motion of atomic hydrogen in amorphous silicon by neutron reflectometry

Preliminary results of neutron reflectometry (NR) measurements on rf sputter-deposited a-Si:H/a-Si:D bilayers indicate that this technique may be used to monitor H and D motions over distances of {approx} 10 to 200 {Angstrom} with a nominal resolution of 5--10 {Angstrom}. In studying rf sputter-deposited thin films containing a high density of microvoids annealed at 270 C, we found that the hydrogen diffused a distance of only {approx} 100 {Angstrom}. Further annealing at 270 and 280 C produced no additional motion. This result is consistent with a model of this system in which the hydrogen is trapped in microvoids after moving a relatively short distance

Interactions Between Land Cover/Use Change and Hydrology

The water cycle is a vital component of the North Eurasian environment and plays a central role in the region’s climate, biology, biogeochemistry and in human interactions with the natural environment. The Northern Eurasian arctic drainage covers more than 2/3 of the pan-arctic land mass. Substantial changes in land cover and land use have occurred over the region in recent decades, as a result of changes in climate, permafrost, and water management, among other factors. These changes are likely to affect large-scale linkages between the regional and global climate system, but the nature of these interactions is not well understood. In this chapter, we analyze changes in the dominant hydrological components and explore the interaction of the terrestrial and atmospheric water cycles, with particular attention to key regional cryospheric processes and linkages between the water and carbon cycles. The monitoring of the water cycle from observational networks and remote sensing along with strategies for improving hydrological change detection are discussed in the context of changes in land cover and land use

From adversity to psychosis: pathways and mechanisms from specific adversities to specific symptoms

Purpose Although there is considerable evidence that adversities in childhood such as social deprivation, sexual abuse, separation from parents, neglect and exposure to deviant parental communication are associated with psychosis in later life, most studies have considered broad diagnoses as outcomes. In this review we consider evidence for pathways between specific types of adversity and specific symptoms of psychosis. Methods We present theoretical arguments for expecting some degree of specificity (although by no means perfect specificity) between different kinds of adversity and different symptoms of psychosis. We review studies that have investigated social–environmental risk factors for thought disorder, auditory–verbal hallucinations and paranoid delusions, and consider how these risk factors may impact on specific psychological and biological mechanisms. Results Communication deviance in parents has been implicated in the development of thought disorder in offspring, childhood sexual abuse has been particularly implicated in auditory–verbal hallucinations, and attachment-disrupting events (e.g. neglect, being brought up in an institution) may have particular potency for the development of paranoid symptoms. Current research on psychological mechanisms underlying these symptoms suggests a number of symptom-specific mechanisms that may explain these associations. Conclusions Few studies have considered symptoms, underlying mechanisms and different kinds of adversity at the same time. Future research along these lines will have the potential to elucidate the mechanisms that lead to severe mental illness, and may have considerable clinical implications