A framework for evaluating business lead users’ virtual reality innovations in Second Life

This paper extends von Hippel’s (Manag. Sci. 32(7):791–805, 1986) concept of lead users to a virtual reality environment. Three lead user groups, site developers, business firms and avatars, have a synergistic role to play in extending virtual reality from a social networking platform to a commercial one. The paper proposes a framework for assessing the extent to which innovative practices have been demonstrated by lead user business firms in a virtual setting. It applies the framework to twenty pioneering firms that operated within Second Life in 2007, from an avatar’s perspective. The study’s findings indicate that business firms made little use of digital agents, and provided few examples of bricolage. However, they exhibited higher levels of innovation in their use of telepresence and interactivity, which contributed to the achievement of flow. As a single-avatar study, the paper has limited generalizability, however studies with a wider scope will enable further development of this framework.     

Improvement of chemical durability of high expansion glasses by ion exchange

In order to prepare a high expansion glass with good chemical durability, Na₂O · 2SiO₂ glass was ion-exchanged in molten LiNO₃ at 460 to 520° C. A Li₂O rich layer, of 100 to 200 m thickness, was produced on the glass surface. Corrosion rate in hot water (98° C) and thermal expansion coefficient were measured. The thin layer on the surface had a much lower corrosion rate in hot water and a lower expansion coefficient than the bulk glass. Because the ion-exchanged layer was thin with respect to the bulk glass, an overall high expansion was maintained. However, it acted as a protective layer giving rise to improved chemical durability.     

Linking associative and serial list memory: Pairs versus triples.

Paired associates and serial list memory are typically investigated separately. An "isolation principle" (J. B. Caplan, 2005) was proposed to explain behavior in both paradigms by using a single model, in which serial list and paired associates memory differ only in how isolated pairs of items are from interference from other studied items. In the present study, 2 experiments identify a critical dissociation between the 2 paradigms, challenging this unified account. Specifically, forward and backward probes were highly correlated for pairs and less so for short lists (triples). The authors asked whether the isolation principle could quantitatively accommodate this type of dissociation. A simulation confirmed that a single model incorporating the isolation principle can adequately explain this and other dissociations, supporting the common processes view. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Laser‐Assisted Lattice Recovery of Graphene by Carbon Nanodot Incorporation

Producing highly oriented graphene is a major challenge that constrains graphene from fulfilling its full potential in technological applications. The exciting properties of graphene are impeded in practical bulk materials due to lattice imperfections that hinder charge mobility. A simple method to improve the structural integrity of graphene by utilizing laser irradiation on a composite of carbon nanodots (CNDs) and 3D graphene is presented. The CNDs attach themselves to defect sites in the graphene sheets and, upon laser‐assisted reduction, patch defects in the carbon lattice. Spectroscopic experiments reveal graphitic structural recovery of up to 43% and electrical conductivity four times larger than the original graphene. The composites are tested as electrodes in electrochemical capacitors and demonstrate extremely fast RC time constant as low as 0.57 ms. Due to their low defect concentrations, the reduced graphene oxide‐carbon nanodot (rGO‐CND) composites frequency response is sufficiently fast to operate as AC line filters, potentially replacing today's electrolytic capacitors. Using this methodology, demonstrated is a novel line filter with one of the fastest capacitive responses ever reported, and an aerial capacitance of 68.8 mF cm^?2. This result emphasizes the decisive role of structural integrity for optimizing graphene in electronic applications.     

Stabilization of Tetragonal ZrO2 in ZrO2–SiO2 Binary Oxides

Gel-glasses of various compositions in the x ZrO₂^.(10 – x )SiO₂system were fabricated by the sol–gel process. Precipitation due to the different reactivities between tetraethyl orthosilicate (TEOS) and zirconium(IV) n -propoxide has been eliminated through the use of 2-methoxyethanol as a chelating agent. Thermal treatment of these gels produced crystalline ZrO₂particles. While monoclinic is the stable crystalline phase of zirconia at low temperatures, the metastable tetragonal phase is usually the first crystalline phase formed on heat treatment. However, stability of the tetragonal phase is low, and it transforms to the monoclinic phase on further heat treatment. In this study, it has been found that the transformation temperature increases as the SiO₂content in the ZrO₂–SiO₂ binary oxide increases. The most significant results were from samples containing only 2 mol% SiO₂, where the metastable tetragonal phase formed at low temperatures and remained stable over a broad temperature range. X-ray diffraction, transmission electron microscopy, and Fourier transform infrared spectroscopy were used to elucidate the structure of these binary oxides as a function of temperature.     

Modelling fully‐adaptive routing in hypercubes

Analytical models for wormhole‐routed hypercubes with deterministic routing have been widely reported in the literature. A model for the hypercube with fully‐adaptive routing has recently been proposed in [1]. It uses M/M/1 queues, and computes a different probability of blocking at each intermediate router along the message path. As a result, the number of equations, and thus the computation steps, to evaluate latency increases with the network size. This paper proposes an alternative model that uses M/G/1 queues, and requires a constant number of computation steps irrespective of the network size. It achieves this by computing only once the mean probability of blocking across the entire path, and using it to determine the blocking time at a given router. Simulation experiments reveal that the model yields accurate latency results. This revised version was published online in June 2006 with corrections to the Cover Date.     

Exploring connectivity of the brain's white matter with dynamic queries

Diffusion tensor imaging (DTI) is a magnetic resonance imaging method that can be used to measure local information about the structure of white matter within the human brain. Combining DTI data with the computational methods of MR tractography, neuroscientists can estimate the locations and sizes of nerve bundles (white matter pathways) that course through the human brain. Neuroscientists have used visualization techniques to better understand tractography data, but they often struggle with the abundance and complexity of the pathways. In this paper, we describe a novel set of interaction techniques that make it easier to explore and interpret such pathways. Specifically, our application allows neuroscientists to place and interactively manipulate box or ellipsoid-shaped regions to selectively display pathways that pass through specific anatomical areas. These regions can be used in coordination with a simple and flexible query language which allows for arbitrary combinations of these queries using Boolean logic operators. A representation of the cortical surface is provided for specifying queries of pathways that may be relevant to gray matter structures and for displaying activation information obtained from functional magnetic resonance imaging. By precomputing the pathways and their statistical properties, we obtain the speed necessary for interactive question-and-answer sessions with brain researchers. We survey some questions that researchers have been asking about tractography data and show how our system can be used to answer these questions efficiently.     

Chest radiography: a comparison of image quality and effective dose using four digital systems

Image quality (IQ) and effective dose for chest radiography was compared for four digital imaging systems that used three different detector technologies: a-Si/TFT flat-panel detector (FPD), scanning-slot/charge-coupled device (CCD) and photostimuable phosphor (PSP). On each system a phantom was exposed at 125 kV(p) for automatic exposure control (AEC) and 2, 4 and 8 Gy receptor dose using identical geometrical conditions. All images were scored as softcopy images by three observers. The effective dose was calculated for each exposure condition. For AEC, superior IQ was observed for the GE FPD compared with all the other systems, which showed similar IQ performance. For all systems the entrance surface dose associated with AEC was within the European recommendations but variations in the effective dose were observed between the four systems. For identical receptor dose levels superior IQ was observed with the FPDs. Thorascan was noted for its low effective dose and Agfa CR was associated with the highest effective dose. FPD systems showed a better overall performance, followed by the CCD and PSP systems.     

Determination of the percentage of homopolymer component in Ziegler/Natta catalyst linear low-density polyethylene resins using high-temperature cell Fourier transform infrared and partial least squares quantitative analysis technique

A new method for the determination of the percentage of homopolymer component, using high-temperature cell Fourier transform infrared (FT-IR) by partial least squares (PLS) quantitative analysis technique, was developed and applied to Ziegler Natta linear low-density polyethylene (LLDPE). The method is based on the IR spectrum changes between the 730 cm(-1) band and 720 cm(-1) band at the temperature of 110 degrees C, which is near the melting point of the polyethylene. The HD % (the percentage of high-density component, i.e., the percentage of homopolymer component) results obtained by CTREF (CRYSTAF in TREF mode) technique are used as the input data together with the respective FT-IR spectra for PLS analyses to establish a calibration curve. The PLS quality is characterized by a correlation coefficient of 0.997 (cross-validation) using four factors and a root mean square error of calibration (RMSEC) of 0.772. The HD% of the unknown can then be predicted by the PLS software from the unknown FT-IR spectrum. A control resin was tested seven times by CTREF and FT-IR. The HD% of the control resin was 28.59+/-0.88% by CTREF and 29.05+/-2.37% by FT-IR. It was found that the method was applicable for the same comonomer type of LLDPE within a melt index range and density.