This pooled cohort study investigates the association between sleep duration and cognitive decline in a combined analysis of 2 nationally representative aging cohorts.

In this paper, we focus on the problem of question generation (QG). Recent neural networkbased approaches employ the sequence-tosequence model which takes an answer and its context as input and generates a relevant question as output. However, we observe two major issues with these approaches: (1) The generated interrogative words (or question words) do not match the answer type. (2) The model copies the context words that are far from and irrelevant to the answer, instead of the words that are close and relevant to the answer. To address these two issues, we propose an answer-focused and position-aware neural question generation model. (1) By answerfocused, we mean that we explicitly model question word generation by incorporating the answer embedding, which can help generate an interrogative word matching the answer type. (2) By position-aware, we mean that we model the relative distance between the context words and the answer. Hence the model can be aware of the position of the context words when copying them to generate a question. We conduct extensive experiments to examine the effectiveness of our model. The experimental results show that our model significantly improves the baseline and outperforms the state-of-the-art system.

We present the first direct measurement of ion hydration in supercritical water using X-ray absorption fine structure (XAFS). Radial structure functions were determined for strontium ions in supercritical water at 385 "C and 269-339 bar at a concentration of strontium of 0.2 M. For supercritical water, at a temperature of 385 "C and density of 0.54 g/cm3, the number of waters of hydration was a factor of 0.52 of the number in liquid water under ambient conditions. The radius of the first solvation shell changes very little at these elevated temperatures. This large local depletion of water around the ion would affect the short-range interactions with counterions and may increase the ion reactivity. We also report XAFS results for krypton in supercritical water and show that, in contrast to strontium ions, the local solvent environment is more gaslike in the first few solvation shells of the krypton atom. IntroductionSupercritical water (SCW) is an interesting solvent for chemical reactions and hazardous waste At temperatures above 375 "C, the solubility behaviors of two important classes of compounds reverse: most organic species have high solubility whereas the solubility of inorganic salts is limited. The high solubility of organics and the aggressive oxidizing environment are attractive for organic reactions and waste-destruction reactions. The low salt solubility presents both obstacles to and opportunities in developing SCW oxidation technology. Salt precipitation may lead to equipment fouling and erosion. However, the ability to control solubility with temperature and pressure may provide a way of separating organic from inorganic wastes and may provide a way of selectively separating different salts. A better understanding of the mechanism of salt solubility in SCW is required to fully utilize this unique solvent. In this Letter, we report X-ray absorption fine structure (XAFS) measurements of the extent of ion hydration in SCW. From these results, one can build a picture of the radial distribution of water around the ion, which is important information needed in the development and testing of models of these systems.In the supercritical state, all of the properties of the fluid, including the solvent strength, are "tunable" through adjustments in the fluid density. It is this variable nature of the fluid that makes SCW (Z', = 374 "C, Pc = 220 bar) interesting from a fundamental point of view. For liquid-phase systems, there is only a very narrow latitude for changing the properties of the solvent. In the supercritical fluid or near-critical liquid state, the density of the solution can be changed over a considerable range, offering the opportunity to fully test models of these systems over a wide range of thermodynamic conditions.To a large extent, the dielectric constant of water controls the solubility of ionic species. In the supercritical region, the dielectric constant, E , spans the range from about 5 to 20,6s7 a value that is greatly reduced from the liquid phase ( E 80).Because of the inability of...

The x-ray fluorescence and absorption of highly oriented pyrolytic graphite have been measured using monochromatic synchrotron radiation. The spectra can be separated into contributions from~and oband components by measuring at different angles of incidence and at different emission angles. The shape of the x-ray fluorescence spectra varies dramatically with excitation energy near the C E edge.This dependence on excitation energy can be interpreted within a resonant-inelastic-scattering formalism. The results are compared with previously published band-structure calculations and photoemission results, and demonstrate the potential for using x-ray fluorescence to obtain symmetry-resolved band information.