153,175 research outputs found

    Evaluating electronic textbooks : a methodology

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    EBONI (Electronic Books ON-screen Interface) [1] builds on the premise to emerge from the Visual Book [2] and WEB Book projects [3], that appearance is important in the design of electronic textbooks, and offers an evaluation model, or general methodology, from which ebook usability experiments in a range of areas can be extracted and remain comparable at a basic level. The methodology sets out options for selecting material, participants, tasks and techniques, which vary in cost and level of sophistication. Results from each study will feed into a set of best practice guidelines for producing electronic textbooks on the Web, reflecting the requirements of students and academics throughout the UK

    The analysis of the X-ray event analyzer proportional counter data: A comment

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    The findings, based on a comparison of simultaneous observations of a number of flares obtained with the X-REA and SOLRAD 9 instruments, which reveal the degree of deterioration of the counters with time are presented

    Observation of the X-ray source Sco X-1 from Skylab

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    An attempt to observe the discrete X-ray source Sco X-1 on 20 September 1973 between 0856 and 0920 UT is reported. Data obtained with the ATM/S-056 X-ray event analyzer, in particular the flux observed with the 1.71 to 4.96 KeV counter, is analyzed. No photographic image of the source was obtained because Sco X-1 was outside the field of view of the X-ray telescope

    Results of coronal hole research: An overview

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    An overview of the last 10 years of coronal hole research, in particular since 1970, is presented. The findings of the early investigations and the more recent results obtained with Skylab/Apollo Telescope Mount instrumentation are discussed

    From the visual book to the WEB book : the importance of design

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    This paper presents the results of two studies into electronic book production. The Visual book study explored the importance of the visual component of the book metaphor for the production of more effective electronic books, while the WEB book study took the findings of the Visual book and applied them to the production of books for publication on the World Wide Web (WWW). Both studies started from an assessment of which kinds of paper book are more suitable for translation into electronic form. Both also identified publications which are meant to be used for reference rather than those which are read sequentially, and usually in their entirety. This group includes scientific publications and textbooks which were both used as the target group for the Visual book and the WEB book experiments. In this paper we discuss the results of the two studies and how they could influence the design and production of more effective electronic books

    Terror threat perception and its consequences in contemporary Britain

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    The terrorist attacks of 9/11, and subsequent terrorist acts around the world, have alerted social psychologists to the need to examine the antecedents and consequences of terrorist threat perception. In these two studies we examined the predictive power of demographic factors (age, sex, location), individual values and normative influences on threat perception and the consequences of this perception for behavioural change and close relationships. In study 1 (N = 100) gender, benevolence values and normative influences were all correlates of threat perception, whilst sense of personal threat was correlated with increased contact with friends and family. In study 2 (N = 240) age, sex, location, and the values of Openness to Change and Hedonism, all predicted threat perception, which in turn predicted behavioural change and relationship contact. Such findings point to the important role social psychologists should play in understanding responses to these new terrorist threats

    Evidence linking coronal mass ejections with interplanetary magnetic clouds

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    Using proxy data for the occurrence of those mass ejections from the solar corona which are directed earthward, we investigate the association between the post-1970 interplanetary magnetic clouds of Klein and Burlaga and coronal mass ejections. The evidence linking magnetic clouds following shocks with coronal mass ejections is striking; six of nine clouds observed at Earth were preceded an appropriate time earlier by meter-wave type II radio bursts indicative of coronal shock waves and coronal mass ejections occurring near central meridian. During the selected periods when no clouds were detected near Earth, the only type II bursts reported were associated with solar activity near the limbs. Where the proxy solar data to be sought are not so clearly suggested, that is, for clouds preceding interaction regions and clouds within cold magnetic enhancements, the evidence linking the clouds and coronal mass ejections is not as clear; proxy data usually suggest many candidate mass-ejection events for each cloud. Overall, the data are consistent with and support the hypothesis suggested by Klein and Burlaga that magnetic clouds observed with spacecraft at 1 AU are manifestations of solar coronal mass ejection transients

    The Influence of Nuclear Composition on the Electron Fraction in the Post-Core-Bounce Supernova Environment

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    We study the early evolution of the electron fraction (or, alternatively, the neutron-to-proton ratio) in the region above the hot proto-neutron star formed after a supernova explosion. We study the way in which the electron fraction in this environment is set by a competition between lepton (electron, positron, neutrino, and antineutrino) capture processes on free neutrons and protons and nuclei. Our calculations take explicit account of the effect of nuclear composition changes, such as formation of alpha particles (the alpha effect) and the shifting of nuclear abundances in nuclear statistical equilibrium associated with cooling in near-adiabatic outflow. We take detailed account of the process of weak interaction freeze-out in conjunction with these nuclear composition changes. Our detailed treatment shows that the alpha effect can cause significant increases in the electron fraction, while neutrino and antineutrino capture on heavy nuclei tends to have a buffering effect on this quantity. We also examine the effect on weak rates and the electron fraction of fluctuations in time in the neutrino and antineutrino energy spectra arising from hydrodynamic waves. Our analysis is guided by the Mayle & Wilson supernova code numerical results for the neutrino energy spectra and density and velocity profiles.Comment: 38 pages, AAS LaTeX, 8 figure
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