19,586 research outputs found

    Space telescope phase B definition study. Volume 2A: Science instruments, astrometer

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    The analysis and design of an astrometer instrument for the space telescope are discussed. The design concepts utilize the astrometric multiplexing area scanner and the OTA fine guidance sensor

    The experience of enchantment in human-computer interaction

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    Improving user experience is becoming something of a rallying call in human–computer interaction but experience is not a unitary thing. There are varieties of experiences, good and bad, and we need to characterise these varieties if we are to improve user experience. In this paper we argue that enchantment is a useful concept to facilitate closer relationships between people and technology. But enchantment is a complex concept in need of some clarification. So we explore how enchantment has been used in the discussions of technology and examine experiences of film and cell phones to see how enchantment with technology is possible. Based on these cases, we identify the sensibilities that help designers design for enchantment, including the specific sensuousness of a thing, senses of play, paradox and openness, and the potential for transformation. We use these to analyse digital jewellery in order to suggest how it can be made more enchanting. We conclude by relating enchantment to varieties of experience.</p

    The use of ERTS-1 data for the inventory of critical land resources for regional land use planning

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    Computer-generated spatial and statistical comparisons of critical land resource data derived from conventional sources, RB-57 photographs, and ERTS images, for an eastern Wisconsin test site, suggest that certain critical land resource data can be mapped from ERTS images on a statewide basis. This paper presents one of the biotic resources, wetlands, as an example of the use of ERTS imagery to inventory land resources

    Models of the ICM with Heating and Cooling: Explaining the Global and Structural X-ray Properties of Clusters

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    (Abridged) Theoretical models that include only gravitationally-driven processes fail to match the observed mean X-ray properties of clusters. As a result, there has recently been increased interest in models in which either radiative cooling or entropy injection play a central role in mediating the properties of the intracluster medium. Both sets of models give reasonable fits to the mean properties of clusters, but cooling only models result in fractions of cold baryons in excess of observationally established limits and the simplest entropy injection models do not treat the "cooling core" structure present in many clusters and cannot account for entropy profiles revealed by recent X-ray observations. We consider models that marry radiative cooling with entropy injection, and confront model predictions for the global and structural properties of massive clusters with the latest X-ray data. The models successfully and simultaneously reproduce the observed L-T and L-M relations, yield detailed entropy, surface brightness, and temperature profiles in excellent agreement with observations, and predict a cooled gas fraction that is consistent with observational constraints. The model also provides a possible explanation for the significant intrinsic scatter present in the L-T and L-M relations and provides a natural way of distinguishing between clusters classically identified as "cooling flow" clusters and dynamically relaxed "non-cooling flow" clusters. The former correspond to systems that had only mild levels (< 300 keV cm^2) of entropy injection, while the latter are identified as systems that had much higher entropy injection. This is borne out by the entropy profiles derived from Chandra and XMM-Newton.Comment: 20 pages, 15 figures, accepted for publication in the Astrophysical Journa

    Optimality Theory as a Framework for Lexical Acquisition

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    This paper re-investigates a lexical acquisition system initially developed for French.We show that, interestingly, the architecture of the system reproduces and implements the main components of Optimality Theory. However, we formulate the hypothesis that some of its limitations are mainly due to a poor representation of the constraints used. Finally, we show how a better representation of the constraints used would yield better results

    From protest to agenda building: Description bias in media coverage of protest events in Washington, D.C

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    Social movements often seek to draw attention to issues they deem important by organizing public demonstrations with the aim of attracting mass media coverage. But only a small proportion of all public demonstrations receives any media attention. This article asks whether even the minimal coverage that demonstrations receive reveal any influence of social movements in shaping how issues are framed by the mass media. Analyzing newspaper and television news stories on Washington, D.C. protests held during 1982 and 1991, we ask whether news reports on protests are framed in ways consistent with the aims of protesters. Do demonstrators receive media coverage that highlights the issues about which they are concerned, or does coverage focus on the protest event itself, to the exclusion of the social issues that movements target? Our results support much of the surmising among media scholars, that even when movements succeed at obtaining the attention of mass media outlets, media reports portray protests in ways that may undermine social movement agendas. Despite this obstacle to communicating protest messages through demonstrations, movements engage in other forms of communication that can affect public interpretations of mass media frames

    Buoyancy waves in Pluto's high atmosphere: Implications for stellar occultations

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    We apply scintillation theory to stellar signal fluctuations in the high-resolution, high signal/noise, dual-wavelength data from the MMT observation of the 2007 March 18 occultation of P445.3 by Pluto. A well-defined high wavenumber cutoff in the fluctuations is consistent with viscous-thermal dissipation of buoyancy waves (internal gravity waves) in Pluto's high atmosphere, and provides strong evidence that the underlying density fluctuations are governed by the gravity-wave dispersion relation.Comment: Accepted 18 June 2009 for publication in Icaru
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