Elevation changes in Pine Island Glacier,Walgreen Coast,Antarctica, based on GLAS (2003) and ERS‐1 (1995) altimeter data analyses and glaciological implications

The Geoscience Laser Altimeter System (GLAS) aboard ICESat, launched in January 2003, has been designed to detect and monitor changes in the cryosphere. The first objective of this paper is to present high‐resolution ice‐surface elevation maps derived from GLAS data, using geostatistical analysis. In a regional study of Walgreen Coast and Northern Ellsworth Land, West Antarctica, differences in the representation of geographic and morphologic features in maps based on ERS‐1 radar altimeter data and on GLAS data are investigated, with the result that in particular in topographically complex coastal areas and the margin of the ice sheet the improvement in precision and accuracy of the laser altimeter is significant.

A second, applied objective is to map elevation changes in Pine Island Glacier, a glacier that plays a key role in the question of stability of the West Antarctic Ice Sheet and has been changing rapidly in recent years. Results of elevation differencing of 2003‐GLAS‐data and 1995‐ERS‐1‐radar‐altimeter‐data DEMs (1) show that thinning rates have been increasing and (2) are applied to attribute the observed changes in Pine Island Glacier to internal processes in the glacier, related to dynamic thinning. More generally, this application serves to demonstrate that GLAS data facilitate study of cryospheric change.     

Chaos theory as a model for interpreting information systems in organizations

Abstract.  Chaos theory concerns the qualitative study of unstable aperiodic behaviour in deterministic non-linear dynamical systems. Concepts from chaos theory have recently been applied as a model for interpreting organizational change and understanding organizational behaviour. This paper applies these concepts to the study of information systems in organizations. Key concepts from chaos theory are identified and used to develop an interpretive framework. The importance of understanding the initial conditions when an information systems strategy is developed or an information system is implemented is highlighted. The idea of strange attractors, patterns of behaviours of information systems, organizations and actors, which are repeated is developed, and the effect of internal and external events and choices is considered. These chaos theory concepts are applied to a case study of information systems strategy implementation in the UK probation service. It is concluded that concepts from chaos theory offer valuable support in developing a coherent and meaningful story concerning interactions between information systems and their host organizations.     

Role of Executive Functioning in Verbal and Visual Memory.

G. Tremont, S. Halpert, D. J. Javorsky, and R. A. Stern (2000) found that individuals with executive dysfunction were more impaired on less structured versus more structured verbal memory tasks. In the present study, the authors investigated the relationship between executive functions and memory in patients with a history of traumatic brain injury by examining the effect of executive functioning on more structured and less structured verbal and visual memory tasks at baseline and 1-year follow-up. Matched subgroups controlled for differences in severity of neuropsychological impairment unrelated to specific executive functions. The G. Tremont et al. (2000) findings were not replicated. Results showed that when acuteness and severity of injury were controlled, executive impairment played no significant role in performance on either more or less structured memory tasks. However, regardless of structure, executive functions played a role in visual memory performance, suggesting that visual memory may be a more fluid ability than verbal memory. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A Randomized Trial Comparing the Effects of Self-Help Materials and Proactive Telephone Counseling on Teen Smoking Cessation.

We conducted a 2-arm randomized trial to test the efficacy of self-help materials with or without proactive telephone counseling to increase cessation among teen smokers. Teen smokers (N = 402) recruited from 11 shopping malls and 1 amusement park in the southeastern United States were randomized to 1 of 2 groups: written self-help material plus video; or written self-help material, video, and telephone counseling. Cessation rates based on 7-day point-prevalent abstinence for the self-help and counseling arms were 11% and 16%, respectively (p = .25), at 4 months postbaseline and 19% and 21%, respectively (p = .80), at 8 months postbaseline. Sustained abstinence, reflecting 7-day abstinence at both time points, in the self-help and counseling arms was 7% and 9% (p = .59). Results suggest that minimal self-help cessation approaches that target youth have comparable success to that shown among adult smokers. However, refinements in telephone-counseling approaches may be needed to achieve the success observed in adult populations. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Balancing optical path lengths in broadband fiber interferometers

A simple model is used to show that control of dispersion in an all-fiber stellar interferometer is feasible. From the results we assume that an interferometer control system is available in which both temperature and strain are used to balance the interferometer. Within the restriction of a single polarization mode, it is shown that vacuum path errors before the coupling of starlight into the fibers as well as fiber-length differences and environmental differences between two fibers can be corrected to high order.     

Two‐Stage Reactive Polymer Network Forming Systems

There are distinct advantages to designing polymer systems that afford two distinct sets of material properties– an intermediate polymer that would enable optimum handling and processing of the material, while maintaining the ability to tune in different, final polymer properties that enable the optimal functioning of the material. In this study, by designing a series of non‐stoichiometric thiol‐acrylate systems, a polymer network is initially formed via a base catalyzed Michael addition reaction that proceeds stoichiometrically via the thiol‐acrylate “click” reaction. This self‐limiting reaction results in a polymer with excess acrylic functional groups within the network. At a later point in time, the photoinitiated, free radical polymerization of the excess acrylic functional groups results in a highly crosslinked, robust material system. These two stage reactive thiol‐acrylate networks that have intermediate stage rubbery moduli and glass transition temperatures that range from 0.5 MPa and ‐10 °C to 22 MPa and 22 °C, respectively, are formulated and characterized. The same polymer networks can then attain glass transition temperatures that range from 5 °C to 195 °C and rubbery moduli of up to 200 MPa after the subsequent photocuring stage. The two stage reactive networks formed by varying the stoichiometric ratios of the thiol and acrylate monomers were shown to perform as substrates for three specific applications: shape memory polymers, impression materials, and as optical materials for writing refractive index patterns.     

Multiparameter self-optimizing systems using correlation techniques

A class of self-optimizing systems which continually alter their parameters to reduce a mean-square performance criterion is described. The change in each parameter is determined from an error gradient in parameter space computed by cross-correlation methods which are independent of signal spectra and require no test signal or parameter perturbation. Applications of this technique to both open-loop and closed-loop systems are included and it is shown that a combination of such self-optimizing systems is a possible solution to the adaptive control problem. Computer simulation results are included to demonstrate the practicality of the proposed systems.     

Design of smart sensing components for volcano monitoring

In a volcano monitoring application, various geophysical and geochemical sensors generate continuous high-fidelity data, and there is a compelling need for real-time raw data for volcano eruption prediction research. It requires the network to support network synchronized sampling, online configurable sensing and situation awareness, which pose significant challenges on sensing component design. Ideally, the resource usages shall be driven by the environment and node situations, and the data quality is optimized under resource constraints. In this paper, we present our smart sensing component design, including hybrid time synchronization, configurable sensing, and situation awareness. Both design details and evaluation results are presented to show their efficiency. Although the presented design is for a volcano monitoring application, its design philosophy and framework can also apply to other similar applications and platforms.     

Micro-computer tomography—An aid in the investigation of structural changes in lead zirconate titanate ceramics after temperature-humidity bias testing

Lead zirconate titanate ceramic actuators are extensively used in electronic and electro-mechanical devices. Under humid conditions with a d.c. bias leakage currents increase power consumption In some materials the increasing leakage current is accompanied by the evolution of features on the anode surface, but little is known of any changes to the internal structure of the material. This research applies an advanced imaging technique (micro-computer tomography) to non-destructively investigate these features. This allows the evolution of internal features over time to be studied. The findings reveal that the microstructure of the ceramic was significantly altered during environmental testing.