The effect of matrix microstructure on cyclic response and fatigue behavior of particle- reinforced 2219 aluminum: Part I. room temperature behavior

The low-cycle and high-cycle fatigue behavior and cyclic response of naturally aged and overaged 2219/TiC/15p and unreinforced 2219 Al were investigated using plastic strain-controlled and stress-controlled testing. In addition, the influence of grain size on the particle-reinforced materials was examined. In both reinforced and unreinforced materials, the naturally aged conditions were cyclically unstable, exhibiting an initial hardening behavior followed by an extended region of cyclic stability and ultimately a softening region. The overaged reinforced material was cyclically stable for the plastic strains examined, while the overaged unreinforced material exhibited cyclic hardening at plastic strains greater than 2.5 × 10⁻⁴. Decreasing grain size of particle-reinforced materials modestly increased the cyclic flow stress of both naturally aged and overaged materials. Reinforced and unreinforced materials exhibited similar fatigue life behaviors; however, the reinforced and unreinforced naturally aged materials had superior fatigue lives in comparison to the overaged materials. Grain size had no effect on the fatigue life behavior of the particle-reinforced materials. The fatigue lives were strongly influenced by the presence of clusters of TiC particles and exogenous Al₃Ti intermetallics. formerly Research Assistant with the Department of Materials Science and Engineering, University of Michigan, Ann Arbor, MI 48109 This article is based on a presentation made in the symposium entitled “Creep and Fatigue in Metal Matrix Composites” at the 1994 TMS/ASM Spring meeting, held February 28–March 3, 1994 in San Francisco, California, under the auspices of the Joint TMS-SMD/ASM-MSD Composite Materials Committee.     

Aging and prospective memory: Examining the influences of self-initiated retrieval processes.

Past research has frequently failed to find age differences in prospective memory. This article tested the possibility that age differences would be more likely to emerge on a prospective memory task that was high in self-initiated retrieval. In the 1st experiment, participants were asked to perform an action every 10 min (a time-based task presumed to be high in self-initiated retrieval); in the 2nd experiment, participants were asked to perform an action whenever a particular word was presented (an event-based task presumed to be relatively low in self-initiated retrieval). Age differences were found with the time-based task but not with the event-based task. This pattern of age differences was again found in a 3rd experiment in which a new experimental procedure was used and the nature of the prospective memory task was directly varied. Generally, the results suggest that self-initiated retrieval processes are an important component of age-related differences across both retrospective and prospective memory tasks. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Observations of and applications for self-imaging in optical fibers

Experimental results of self-imaging in optical fibers are reported along with an analytical model that explains the observations. Some implications for sensor design are discussed.     

Comparison of the indentation and elasticity of E. coli and its spheroplasts by AFM

Atomic force microscopy (AFM) provides a unique opportunity to study live individual bacteria at the nanometer scale. In addition to providing accurate morphological information, AFM can be exploited to investigate membrane protein localization and molecular interactions on the surface of living cells. A prerequisite for these studies is the development of robust procedures for sample preparation. While such procedures are established for intact bacteria, they are only beginning to emerge for bacterial spheroplasts. Spheroplasts are useful research models for studying mechanosensitive ion channels, membrane transport, lipopolysaccharide translocation, solute uptake, and the effects of antimicrobial agents on membranes. Furthermore, given the similarities between spheroplasts and cell wall-deficient (CWD) forms of pathogenic bacteria, spheroplast research could be relevant in biomedical research. In this paper, a new technique for immobilizing spheroplasts on mica pretreated with aminopropyltriethoxysilane (APTES) and glutaraldehyde is described. Using this mounting technique, the indentation and cell elasticity of glutaraldehyde-fixed and untreated spheroplasts of E. coli in liquid were measured. These values are compared to those of intact E. coli. Untreated spheroplasts were found to be much softer than the intact cells and the silicon nitride cantilevers used in this study.     

Scanning tunnelling microscopy of tobacco mosaic virus on evaporated and sputter-coated palladium/gold substrates

We present scanning tunnelling microscope (STM) images of untreated tobacco mosaic virus (TMV) deposited on thermally evaporated and on sputter-coated palladium/gold 40:60 (Pd/Au) substrates, and imaged under ordinary atmospheric conditions. The TMV imaged on both evaporated and sputter-coated substrates was consistently several times wider than the known diameter of the virus. TMV on evaporated Pd/Au became overcoated with Pd/Au material during sample preparation and appeared elevated in STM images, whereas TMV on sputter-coated Pd/Au appeared as depressions. When naked TMV were intentionally overcoated with Pd/Au, the STM images were found to be similar to those for TMV on evaporated Pd/Au.     

Comparing true and false confessions among persons with serious mental illness.

Over the past decade, knowledge on false confessions has grown tremendously. However, a similar knowledge base on true confessions has not. In the present study, independent, self-reported true and false confession experiences of persons with serious mental illness were compared. In addition to examining the crimes and police questioning that led to the true or false confession, we investigated the reasons behind the confessions and the eventual case outcomes. We found that, in comparison to true confessors (n = 30), false confessors (n = 35) were questioned more times, took longer to confess, perceived the evidence against them to be weaker, and reported significantly more external pressure and less internal pressure. Moreover, of those participants who were convicted, false confessors were four times more likely to receive a prison sentence than true confessors. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Pervasive information — the key to ‘true’ mobility

Since Weiser’s vision in 1991 for ubiquitous (also called pervasive) computing there has been little tangible progress towards it. However, over time the communications industry has begun to erode many of the hardware barriers to this vision. Even so, the utopia of pervasive computing remains out of reach, primarily as a result of the continued fixation with devices and connectivity as a way to realise mobility. However, it could be argued that users ultimately require access to information or content irrespective of the devices and connectivity around them. Consequently, pervasive information is seen as the key to true user mobility. This paper will introduce a potential secure pervasive information architecture that fits Weiser’s vision, and position it with respect to a sub-set of current contenders for future systems from both academia and the telecommunications industry, and highlight their strengths and weaknesses.