The Influence of Molecular Architecture on the Macroscopic Lubrication Properties of the Brush-Like Co-polyelectrolyte Poly(L-lysine)-g-poly(ethylene glycol) (PLL-g-PEG) Adsorbed on Oxide Surfaces

The co-polymer poly(L-lysine)-g-poly(ethylene glycol) (PLL-g-PEG) has been investigated as a potential biomimetic boundary-lubrication additive for aqueous lubrication systems. In this work, the influence of the co-polymer's architecture on its tribological performance has been investigated. The architectural parameters investigated comprise side-chain (PEG) length, Lys/PEG grafting ratio and backbone chain (PLL) length. The tribological approaches applied in this work include ultra-thin-film interferometry, the mini-traction machine (MTM), and pin-on-disk tribometry. Both an increase in the molecular weight of the PEG side chains and a reduction in the grafting ratio result in an improvement in the lubricating properties of aqueous PLL-g-PEG solution at low speeds. MTM measurements show that an increase in the molecular weight of the PLL backbone results in an increase of the coefficient of friction.     

Walking through CS AKTive Space: a demonstration of an integrated Semantic Web application

We describe CS AKTive Space, an integrated semantic web application and winner of the 2003 Semantic Web Challenge [http://www.challenge.semanticweb.org/]. A demonstration of the application is available at http://cs.aktivespace.org/. CS AKTive Space represents and integrates a wide range of heterogenous resources representing the computer science domain in the UK; it supports the exploration of patterns and implications inherent in the content and exploits a variety of services, visualisations and multidimensional representations to support questions like who is working with whom, where are there geographical concentrations in funding or research area, who are the most significant researchers in an area. We briefly show how this demonstration illustrates a number of substantial challenges for the Semantic Web. These include problems of referential integrity, tractable inference and interaction support. We review our approaches to these issues and discuss relevant related work.     

Multiscale mechanical and structural characterizations of Palmetto wood for bio-inspired hierarchically structured polymer composites

There has been a great deal of effort focused on engineering polymer composites with hierarchical microstructures consisting of one or more ingredients that can be organized differently across multiple length scales. However, there are hierarchical microstructures that have evolved over eons in biological materials. These unique structure–property relationships may serve as templates for engineering hierarchically structured polymer composites with tailored properties. One such biological material is the Palmetto wood of South Carolina, which was successfully used as a protective structure during the Revolutionary and Civil Wars to absorb cannon shot. Through an assembly of microfibers into macrofibers embedded in a cellulose matrix, the Palmetto wood has optimized its ability to resist failure when subjected to extreme dynamic loading events, such as hurricanes. Understanding of the dynamic and static structure–property relationship in Palmetto wood can facilitate the development of new hierarchically structured polymer composites with increased resistance to failure. Therefore, the structure–property relationship in Palmetto wood has been studied using novel multiscale microstructural and mechanical characterization techniques. Models have been developed that indicate that the hierarchical structure of Palmetto wood obeys the linear Rule-of-Mixtures across multiple length scales. This understanding has led to the development of new polymer composite structures that exhibit properties similar to Palmetto wood using conventional laminated carbon fiber–epoxy composites and new polymer nanocomposites consisting of carbon nanofibers. The use of the nanofibers appears to enhance the interaction between the composite components in a manner similar to the interaction between fibers in the Palmetto wood that enables the laminated composite to behave more like the individual layers by resisting the tendency to delaminate and increasing the Weibull statistical parameters closer to those observed in Palmetto wood.     

Child and parent effects in boys' conduct disorder: A reinterpretation.

The importance of parent and child influences on the development of conduct disorder (CD) in boys is evaluated. The research approaches reviewed include studies of interactions between unrelated mothers and children, reaction to punishment, autonomic reactivity, biochemical factors, and drug treatment and longitudinal studies of delinquency. Evidence from this research and from research on parental influences, reviewed in detail elsewhere, is interpreted as demonstrating the primacy of the child's own contribution to CD within a reciprocal parent–child interactive system, thus corroborating control systems theory (R. Q. Bell, 1977). Demonstrated parental influences are interpreted as actions that are elicited by or that exacerbate the child's tendencies and that may represent genetic continuities. The heuristic utility and consequences of this model are outlined. It is emphasized that child effects do not imply immutability of behavior. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Spectral sensing of foliar water conditions in two co-occurring conifer species: Pinus edulis and Juniperus monosperma

Many fundamental ecosystem properties and dynamics are determined by plant water stress, particularly in dryland ecosystems where water is usually limiting. Indeed, under severe drought, plant water stress and associated insect infestations can produce landscape-scale mortality. Despite the fundamental importance of plant water stress in determining properties and dynamics at ecosystem and landscape scales, approaches for remotely sensing plant water stress are largely lacking, particularly for conifers. We evaluated the remotely sensed detection of foliar drought stress in two conifer species, Pinus edulis and Juniperus monosperma, which are co-dominants of extensive-juniper woodlands in North America, the first of which experienced extensive mortality in association with a recent drought. Needle spectra were made on these species in the field using an integrating sphere and portable spectrometer. Two indices of foliar water condition, plant water content (% of dry mass) and plant water potential, were compared to five spectral analyses: continuum removal of the 970 and 1200 nm water absorption features, the Normalized Difference Water Index (NDWI), the Normalized Difference Vegetation Index (NDVI), and the red edge wavelength position. For P. edulis, plant water content was significantly correlated with four of the five indices: NDVI (R²=0.71) and NDWI (R²=0.68) which exhibited stronger relationships than 970 nm continuum removal (R²=0.57) or red edge position (R²=0.45). All five indices were significantly correlated with P. edulis water content when trees undergoing mortality were included in analyses (R²=0.60-0.93). Although the correlations were weaker than for plant water content, plant water potential was significantly correlated with NDWI (R²=0.49), 970 nm (R²=0.44), NDVI (R²=0.35), and red edge (R²=0.34); again all five indices had significant relationships when trees undergoing mortality were included (R²=0.51-0.86). The relationships were weaker for J. monosperma: water content was significantly related to 970 nm (R²=0.50) and 1200 nm (R²=0.37) continuums and NDVI (R²=0.33), while water potential was related only to 1200 nm (R²=0.40). Our results demonstrate a critical link between plant physiological characteristics tied to water stress and associated spectral signatures for two extensive co-occurring conifer species.     

An examination of decision-makers' utilization of decision support system output

A study was conducted of 18 decision support systems in major U.S. corporations in order to examine their methods of operation and the ways in which the DSS contribute to the decision making process. These DSS were studied with respect to organizational level of the decision maker, phases of the decision making process, interaction among decision makers using the DSS, requirement for and regularity of DSS use, impact on job tasks and performance, and perceived value of the DSS. Study results provide substantial support for generalized conceptualizations in the literature. Decision support is primarily for upper and/or middle management working in interaction. Use of the DSS is at the discretion of the decision maker and the majority of DSS users are highly satisfied with their systems.     

Simple MCA Supports a Variety of Applications

A greatly enhanced version of the Violinist I, Simple Multichannel Analyzer has been developed at Los Alamos. The new instrument includes a more powerful microprocessor, more memory, and a sophisticated set of I/O devices. The combination of these features allow the same basic electronics package to function in a variety of "smart" sophisticated monitoring instruments. Only the packaging, detector, and software need be changed to change the instrument from a field survey instrument for Pu contamination to a continuous air monitor to a neutron dosimeter. This instrument should spawn a new generation of user-friendly, highly effective instrumentation.     

Interactive computer graphics applied to the theoretical aircraft/store separation problem

Recently, a computer program was developed which computes the theoretical trajectory of a store in the complex flow field after release from an aircraft flying at subsonic speeds. However, the engineer still had the exceptionally difficult problem of preparing the source and sink models which are part of the computer program input.Views of the interactive graphics console illustrate how an interactive graphics computer program (SOURCE) is used to prepare source and sink theoretical aerodynamic models for the aircraft fuselage, nacelles, fuel tanks, and store bodies. Use of this interactive graphics computer program reduces the calendar time required to develop a source and sink model from approximately 2 weeks to 1 h. This reduction in required calendar time permits theoretical store separation analyses to be conducted for a store in the early development program when the store shape is frequently being changed.