Precipitous weakening of quartz at the α–β phase inversion

Crystalline quartz has long been identified as among the weakest of abundant crustal minerals. This weakness is particularly evident around the α–β phase inversion at 573°C, in which Si–O bonds undergo a displacive structural transformation from trigonal to hexagonal symmetry. Here we present data using indentation testing methodologies that highlight the precipitous extent of the transformational weakening. Although the indentations are localized over relatively small specimen contact areas, the data quantify the essential deformation and fracture properties of quartz in a predominantly (but not exclusively) compressive stress field, at temperatures and pressures pertinent to conditions in the earth's crust.     

Disgust as a disease-avoidance mechanism.

Many researchers have claimed that the emotion of disgust functions to protect us from disease. Although there have been several discussions of this hypothesis, none have yet reviewed the evidence in its entirety. The authors derive 14 hypotheses from a disease-avoidance account and evaluate the evidence for each, drawing upon research on pathogen avoidance in animals and empirical research on disgust. In all but 1 case, the evidence favors a disease-avoidance account. It is suggested that disgust is evoked by objects/people that possess particular types of prepared features that connote disease. Such simple disgusts are directly disease related, are acquired during childhood, and are able to contaminate other objects/people. The complex disgusts, which emerge later in development, may be mediated by several emotions. In these cases, violations of societal norms that may subserve a disease-avoidance function, notably relating to food and sex, act as reminders of simple disgust elicitors and thus generate disgust and motivate compliance. The authors find strong support for a disease-avoidance account and suggest that it offers a way to bridge the divide between concrete and ideational accounts of disgust. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Pacemaker interference by magnetic fields at power line frequencies

Human exposure to external 50/60-Hz electric and magnetic fields induces electric fields within the body. These induced fields can cause interference with implanted pacemakers. In the case of exposure to magnetic fields, the pacemaker leads are subject to induced electromotive forces, with current return paths being provided by the conducting body tissues. Modern computing resources used in conjunction with millimeter-scale human body conductivity models make numerical modeling a viable technique for examining any such interference. In this paper, an existing well-verified scalar-potential finite-difference frequency-domain code is modified to handle thin conducting wires embedded in the body. The effects of each wire can be included numerically by a simple modification to the existing code. Results are computed for two pacemaker lead insertion paths, terminating at either atrial or ventricular electrodes in the heart. Computations are performed for three orthogonal 60-Hz magnetic field orientations. Comparison with simplified estimates from Faraday's law applied directly to extracorporeal loops representing unipolar leads underscores problems associated with this simplified approach. Numerically estimated electromagnetic interference (EMI) levels under the worst case scenarios are about 40 microT for atrial electrodes, and 140 microT for ventricular electrodes. These methods could also be applied to studying EMI with other implanted devices such as cardiac defibrillators.     

Polychronicity, the Internet, and the Mass Media: A Singapore Study

Polychronicity is time-use preference, which people acquire through socialization. The literature shows that polychrons, who favor simultaneous activities, and monochrons, who favor linear activities, exhibit different perceptual and behavioral patterns. This article examines the relationship among polychronicity, Internet skills, Internet use, and Internet perception. In addition, it investigates the hypothesis that Internet use displaces other activity. A total of 1,048 adult Singapore citizens and permanent residents participated in a computer-assisted telephone interview. Of these, 380 were non-Internet users and 668 were users. For the purpose of this study, only responses from the 668 Internet users were included in the analyses. Two-stage least squares regression analyses showed that polychronicity was not associated with Internet use, but it predicted Internet perception. Internet skills positively predicted Internet use and perception. The Internet neither displaced nor promoted television viewing, radio listening, and newspaper reading. However, there was some indication that polychronicity suppressed television viewing.     

探索PCI Express沟通芯片道

PCI Express技术可提供极快的速度、彻底改变通讯模式的特性已被业界广泛讨论,但很少有人论及PCI Express如何让芯片间进行通讯.在先前一系列PCI Express架构的技术文章中,我们已从虚拟通道的议题,一路探讨到应用与PC架构的领域.然而,连接PCI Express(PCIe)与ExpressCard组件的可编程接口是我们尚未探讨的主题,本文将针对该主题进行深入的探讨.     

Characterization by pyrolysis-gas chromatography-mass spectrometry of the insoluble organic residues derived from the hydrogenation of Tasmanites sp. oil shale

The insoluble organic residues from the hydrogenation of Tasmanites sp. oil shale have been characterized by Curie point pyrolysis combined with gas chromatography and computerized gas chromatography-mass spectrometry. The resulting pyrograms show that very little, if any, hydrogenation of the residues occurs. Rather, the initial step in the sequence is pyrolysis of the residue followed by hydrogenation of the liquid products. Major compounds identified from the pyrograms of the residues include alkene/alkane doublets, mixtures of diterpenoids and mono- di- and triaromatic compounds. Changes in the distribution of these compounds with changes in reaction conditions are discussed.     

Solar thermal electric power systems: Comparison of line-focus collectors

Three types of line-focusing collectors: parabolic though, fixed slats with movable absorber and movable slats with fixed absorber, are evaluated to find those systems that are capable of producing the lowest costs of electrical energy. Minimum costs per kW-hr are found using sequential optimization techniques that consider variations in rim angle, reflectance, aperture width, length, orientation, tracking, contour error, slat width, slat curvature, tangent slat angle, slope, installation methods, materials, fabrication methods, absorptance, emittance, cover transmittance, field shape, layout, pipe sizes, insulation thicknesses and turbine-generator-cooling lower efficiencies and designs. This approach provides a uniform treatment of both cost and performance for a solar thermal electric power system. This uniform treatment of solar thermal electric power systems for all collector types insures that valid comparisons are made.     

Chiral discrimination of basic and hydrophobic molecules by chemical force spectroscopy

Chemical force spectroscopy (CFS) is becoming a powerful technique with which to measure intermolecular forces. The prime advantage over other techniques is the ability to map spatial distribution of ligands on the surface. We have used CFS to explore the binding force of a variety of different chiral molecules in order to understand more about the nature of what is a fundamental aspect of chemical biology and of central importance in pharmacology.     

Measuring client satisfaction with public education I: meeting competing demands in establishing state-wide benchmarks

By its very nature, a large-scale evaluation of client satisfaction with public education using a quantitative approach, places almost impossibly competing demands on the research methodology. This paper reports on the use of a suite of Rasch measurement techniques to meet the competing demands in establishing state-wide benchmarks relating to the School Opinion Survey carried out over 1200 government schools in one state of Australia. Although the evaluation had to establish system-wide representative parent and student benchmarks, meaningful quantitative estimates of client satisfaction had to be provided at the smallest public schools. The final 20-item School Opinion Survey Parent and Student Forms were designed following feedback from the administration of trial forms. Instrument development was monitored by the results of Rasch modeling. The Rasch modeling property of specific objectivity was empirically verified when calculation of identical benchmark estimates resulted from the construction of simulated population proportional samples using sample:population size weightings.     

Virus Matryoshka: A Bacteriophage Particle—Guided Molecular Assembly Approach to a Monodisperse Model of the Immature Human Immunodeficiency Virus

Immature human immunodeficiency virus type 1 (HIV‐1) is approximately spherical, but is constructed from a hexagonal lattice of the Gag protein. As a hexagonal lattice is necessarily flat, the local symmetry cannot be maintained throughout the structure. This geometrical frustration presumably results in bending stress. In natural particles, the stress is relieved by incorporation of packing defects, but the magnitude of this stress and its significance for the particles is not known. In order to control this stress, we have now assembled the Gag protein on a quasi‐spherical template derived from bacteriophage P22. This template is monodisperse in size and electron‐transparent, enabling the use of cryo‐electron microscopy in structural studies. These templated assemblies are far less polydisperse than any previously described virus‐like particles (and, while constructed according to the same lattice as natural particles, contain almost no packing defects). This system gives us the ability to study the relationship between packing defects, curvature and elastic energy, and thermodynamic stability. As Gag is bound to the P22 template by single‐stranded DNA, treatment of the particles with DNase enabled us to determine the intrinsic radius of curvature of a Gag lattice, unconstrained by DNA or a template. We found that this intrinsic radius is far larger than that of a virion or P22‐templated particle. We conclude that Gag is under elastic strain in a particle; this has important implications for the kinetics of shell growth, the stability of the shell, and the type of defects it will assume as it grows.