Arizona State University

About: Arizona State University is a education organization based out in Tempe, Arizona, United States. It is known for research contribution in the topics: Population & Poison control. The organization has 40425 authors who have published 109662 publications receiving 4488331 citations. The organization is also known as: Arizona State & ASU Tempe.

An Experimental Study of Water and Carbon Dioxide Solubilities in Mid-Ocean Ridge Basaltic Liquids. Part I: Calibration and Solubility Models

Abstract: Experiments were conducted to determine the solubilities of H_2O and CO_2 and the nature of their mixing behavior in basaltic liquid at pressures and temperature relevant to seqfloor eruption. Mid-ocean ridge basaltic (MORB) liquid was equilibrated at 1200°C with pure H_2O at pressures of 176–717 bar and H_2O—CO_2 vapor at pressures up to 980 bar. Concentrations and speciation of H_2O and CO_2 dissolved in the quenched glasses were measured using IR spectroscopy. Molar absorptivities for the 4500 cm^(−1) band of hydroxyl groups and the 5200 and 1630 cm^(−1) bands of molecular water are 0⋅67±0⋅03, 0⋅62±0⋅07, and 25±3 l/mol-cm, respectively. These and previously determined molar absorptivities for a range of silicate melt compositions correlate positively and linearly with the concentration of tetrahedral cations (Si+Al). The speciation of water in glass quenched from vapor-saturated basaltic melt is similar to that determined by Silver & Stolper (Journal of Petrology 30, 667–709, 1989) in albitic glass and can be fitted by their regular ternary solution model using the coefficients for albitic glasses. Concentrations of molecular water measured in the quenched basaltic glasses are proportional to fH_2O in all samples regardless of the composition of the vapor, demonstrating that the activity of molecular water in basaltic melts follows Henry's law at these pressures. A best fit to our data and existing higher-pressure water solubility data (Khitarov et al., Geochemistry 5, 479–492, 1959; Hamilton et al., Journal of Petrology 5, 21–39, 1964), assuming Henrian behavior for molecular water and that the dependence of molecular water content on total water content can be described by the regular solution model, gives estimates for the V^(o,m)_(H2O) of 12±1 cm^3/mol and for the 1-bar water solubility of 0⋅11 wt%. Concentrations of CO_2 dissolved as carbonate in the melt for pure CO_2-saturated and mixed H_2O-CO_2-saturated experiments are a simple function of f_(CO2). These results suggest Henrian behavior for the activity of carbonate in basaltic melt and do not support the widely held view that water significantly enhances the solution of carbon dioxide in basaltic melts. Using a ΔV^(o,m)_r of 23 cm^3/mol (Pan et al., Geochimica et Cosmochimica Acta 55, 1587–1595, 1991), the solubility of carbonate in the melt at 1 bar and 1200°C is 0⋅5 p.p.m. Our revised determination of CO_2 solubility is ∼20% higher than that reported by Stolper & Holloway (Earth and Planetary Science Letters 87, 397–408, 1988).

Signal enhancement-a composite property mapping algorithm

Abstract: A signal enhancement algorithm is developed that seeks to recover a signal from noise-contaminated distorted measurements made on that signal. This object is achieved by utilizing a set of properties which the signal is known or is hypothesized as possessing. The measured signal is modified to the smallest degree necessary to sequentially possess each of the individual properties. Conditions for the algorithm's convergence are established in which the primary requirement is that a composite property mapping be closed. This is a relatively unrestricted condition in comparison to that required of most existing signal-enhancement algorithms. >

China’s response to a national land-system sustainability emergency

Abstract: China has responded to a national land-system sustainability emergency via an integrated portfolio of large-scale programmes. Here we review 16 sustainability programmes, which invested US$378.5 billion (in 2015 US$), covered 623.9 million hectares of land and involved over 500 million people, mostly since 1998. We find overwhelmingly that the interventions improved the sustainability of China’s rural land systems, but the impacts are nuanced and adverse outcomes have occurred. We identify some key characteristics of programme success, potential risks to their durability, and future research needs. We suggest directions for China and other nations as they progress towards the Sustainable Development Goals of the United Nations’ Agenda 2030.

Urban land teleconnections and sustainability

Abstract: This paper introduces urban land teleconnections as a conceptual framework that explicitly links land changes to underlying urbanization dynamics. We illustrate how three key themes that are currently addressed separately in the urban sustainability and land change literatures can lead to incorrect conclusions and misleading results when they are not examined jointly: the traditional system of land classification that is based on discrete categories and reinforces the false idea of a rural–urban dichotomy; the spatial quantification of land change that is based on place-based relationships, ignoring the connections between distant places, especially between urban functions and rural land uses; and the implicit assumptions about path dependency and sequential land changes that underlie current conceptualizations of land transitions. We then examine several environmental “grand challenges” and discuss how urban land teleconnections could help research communities frame scientific inquiries. Finally, we point to existing analytical approaches that can be used to advance development and application of the concept.

A Knowledge Management Success Model: Theoretical Development and Empirical Validation

Abstract: We examine a knowledge management (KM) success model that incorporates the quality of available knowledge and KM systems built to share and reuse knowledge such as determinants of users' perception of usefulness and user satisfaction with an organization's KM practices. Perceived usefulness and user satisfaction, in turn, affect knowledge use, which in our model is a measure of how well knowledge sharing and reuse activities are internalized by an organization. Our model includes organizational support structure as a contributing factor to the success of KM system implementation. Data collected from 150 knowledge workers from a variety of organizations confirmed 10 of 13 hypothesized relationships. Notably, the organizational support factors of leadership commitment, supervisor and coworker support, as well as incentives, directly or indirectly supported shared knowledge quality and knowledge use. In line with the proposed model, the study lends support to the argument that, in addition to KM systems quality, firms must pay careful attention to championing and goal setting as well as designing adequate reward systems for the ultimate success of these efforts. This is one of the first studies that encompasses both the supply (knowledge contribution) and demand (knowledge reuse) sides of KM in the same model. It provides more than anecdotal evidence of factors that determine successful KM system implementations. Unlike earlier studies that only deal with knowledge-sharing incentives or quality of shared knowledge, we present and empirically validate an integrated model that includes knowledge sharing and knowledge quality and their links to the desired outcome-namely, knowledge reuse.