Hydrogen in stishovite, with implications for mantle water content.

Stishovite, the highest pressure polymorph of silicon dioxide, may be an important mineral in some regions of the Earth's mantle. Fourier transform infrared spectroscopy has been used to determine the hydrogen content of synthetic stishovite. The concentration of hydrogen depends on the aluminum content of the sample and reaches a maximum of 549 +/- 23 hydrogen atoms per 10(6) silicon atoms for an Al(2)O(3) content of 1.51 percent by weight. Stishovite could be a storage site for water in deep subducting slabs and in regions of the mantle that are too hot for hydrous minerals to be stable.

Water sources for subduction zone volcanism: new experimental constraints.

Despite its acknowledged importance, the role of water in the genesis of subduction zone volcanism is poorly understood. Amphibole dehydration in subducting oceanic crust at a single pressure is assumed to generate the water required for melting, but experimental constraints on the reaction are limited, and little attention has been paid to reactions involving other hydrous minerals. Experiments on an oceanic basalt at pressure-temperature conditions relevant to subducting slabs demonstrate that amphibole dehydration is spread over a depth interval of at least 20 kilometers. Reactions involving other hydrous minerals, including mica, epidote, chloritoid, and lawsonite, also release water over a wide depth interval, and in some subduction zones these phases may transport water to deep levels in the mantle.

Nursing activities and acute confusional states in elderly hip-fractured patients.

Confusion in 91 hospitalized patients over 60 years of age who had sustained hip fracture and undergone subsequent surgical repair was examined in seven hospitals in five states. The relationship of nursing activities, patient, surgical, and environmental variables to the extent of confusion apparent in the sample was explored. Data were gathered by record review, patient testing, observation, and interview. Patient testing and interview were carried out on the first, third, and fifth postoperative days; the patient's caregiver on those days was also interviewed. The major dependent variables used in multiple regression analysis were memory (immediate and recent), observed behavior, and patient's self-report of mental clarity. Results showed that the most consistent predictors of postoperative confusion were the presence of confusion on admission to the hospital or confusion during the preoperative period. Greater postoperative mobility and freedom from urinary problems resulted in less confusion. Being male and of increased age were risk factors. The presence of timepieces and patients' use of television were associated with higher levels of mental clarity. Patients in private rooms tended to do better on memory testing than patients in rooms shared with others. Nursing personnel's major action in response to patient confusion was that of conscious attention to orientation, explanation, or reassurance. Use of restraints was relatively frequent.