25,425 research outputs found

    Evocative computing – creating meaningful lasting experiences in connecting with the past

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    We present an approach – evocative computing – that demonstrates how ‘at hand’ technologies can be ‘picked up’ and used by people to create meaningful and lasting experiences, through connecting and interacting with the past. The approach is instantiated here through a suite of interactive technologies configured for an indoor-outdoor setting that enables groups to explore, discover and research the history and background of a public cemetery. We report on a two-part study where different groups visited the cemetery and interacted with the digital tools and resources. During their activities serendipitous uses of the technology led to connections being made between personal memo-ries and ongoing activities. Furthermore, these experiences were found to be long-lasting; a follow-up study, one year later, showed them to be highly memorable, and in some cases leading participants to take up new directions in their work. We discuss the value of evocative computing for enriching user experiences and engagement with heritage practices

    Detection of 84-GHz class I methanol maser emission towards NGC 253

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    We have investigated the central region of NGC 253 for the presence of 84.5-GHz (51405_{-1}\rightarrow4_0E) methanol emission using the Australia Telescope Compact Array. We present the second detection of 84.5-GHz class~I methanol maser emission outside the Milky Way. This maser emission is offset from dynamical centre of NGC 253, in a region with previously detected emission from class~I maser transitions (36.2-GHz 41304_{-1}\rightarrow3_0E and 44.1-GHz 70617_{0}\rightarrow6_1A+^{+} methanol lines) . The emission features a narrow linewidth (\sim12 km s1^{-1}) with a luminosity approximately 5 orders of magnitude higher than typical Galactic sources. We determine an integrated line intensity ratio of 1.2±0.41.2\pm0.4 between the 36.2 GHz and 84.5-GHz class I methanol maser emission, which is similar to the ratio observed towards Galactic sources. The three methanol maser transitions observed toward NGC 253 each show a different distribution, suggesting differing physical conditions between the maser sites and that observations of additional class~I methanol transitions will facilitate investigations of the maser pumping regime.Comment: Accepted into ApJL 12 October 2018. 10 pages, 3 Figures and 2 Table

    Chemical abundances and winds of massive stars in M31: a B-type supergiant and a WC star in OB10

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    We present high quality spectroscopic data for two massive stars in the OB10 association of M31, OB10-64 (B0Ia) and OB10-WR1 (WC6). Medium resolution spectra of both stars were obtained using the ISIS spectrograph on the William Hershel Telescope. This is supplemented with HST-STIS UV spectroscopy and KeckI HIRES data for OB10-64. A non-LTE model atmosphere and abundance analysis for OB10-64 is presented indicating that this star has similar photospheric CNO, Mg and Si abundances as solar neighbourhood massive stars. A wind analysis of this early B-type supergiant reveals a mass-loss rate of M_dot=1.6x10^-6 M_solar/yr,and v_infty=1650 km/s. The corresponding wind momentum is in good agreement with the wind momentum -- luminosity relationship found for Galactic early B supergiants. Observations of OB10W-R1 are analysed using a non-LTE, line-blanketed code, to reveal approximate stellar parameters of log L/L_solar \~ 5.7, T~75 kK, v_infty ~ 3000 km/s, M_dot ~ 10^-4.3 M_solar/yr, adopting a clumped wind with a filling factor of 10%. Quantitative comparisons are made with the Galactic WC6 star HD92809 (WR23) revealing that OB10-WR1 is 0.4 dex more luminous, though it has a much lower C/He ratio (~0.1 versus 0.3 for HD92809). Our study represents the first detailed, chemical model atmosphere analysis for either a B-type supergiant or a WR star in Andromeda, and shows the potential of how such studies can provide new information on the chemical evolution of galaxies and the evolution of massive stars in the local Universe.Comment: 17 pages, 14 figures, MNRAS accepted version, some minor revision

    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 influence of baryons on the mass distribution of dark matter halos

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    Using a set of high-resolution N-body/SPH cosmological simulations with identical initial conditions but run with different numerical setups, we investigate the influence of baryonic matter on the mass distribution of dark halos when radiative cooling is NOT included. We compare the concentration parameters of about 400 massive halos with virial mass from 101310^{13} \Msun to 7.1×10147.1 \times 10^{14} \Msun. We find that the concentration parameters for the total mass and dark matter distributions in non radiative simulations are on average larger by ~3% and 10% than those in a pure dark matter simulation. Our results indicate that the total mass density profile is little affected by a hot gas component in the simulations. After carefully excluding the effects of resolutions and spurious two-body heating between dark matter and gas particles, we conclude that the increase of the dark matter concentration parameters is due to interactions between baryons and dark matter. We demonstrate this with the aid of idealized simulations of two-body mergers. The results of individual halos simulated with different mass resolutions show that the gas profiles of densities, temperature and entropy are subjects of mass resolution of SPH particles. In particular, we find that in the inner parts of halos, as the SPH resolution increases the gas density becomes higher but both the entropy and temperature decrease.Comment: 8 pages, 6 figures, 1 table, ApJ in press (v652n1); updated to match with the being published versio

    NICMOS observations of high redshift radio galaxies: witnessing the formation of bright elliptical galaxies?

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    We present the results of a near infrared imaging program of a sample of 19 radio galaxies with redshift between 1.7 and 3.2, using the NICMOS Camera 2 on the Hubble Space Telescope. The galaxies were observed in H-band which, for 18 of the 19 targets, samples the rest-frame optical emission longwards of the 4000 A break. The images show a wide range of morphologies, from unresolved to compact systems, to systems with substructures such as multiple emission peaks, to systems comprised of several components spread over large areas. The morphologies of 5 of the lowest redshift targets are well represented by a de Vaucouleurs profile, consistent with them being elliptical galaxies. Their average effective radius is a factor of 2 smaller than that of z=1 3CR radio galaxies at similar restframe wavelengths. The near infrared continuum light is generally well aligned with the radio axis and the aligned light has typical V-H colors of around 3.5-4. For several galaxies where WFPC2 images were available, we computed a high resolution map of the optical-to-infrared spectral indices: all multi-component systems present net color gradients between the various clumps. We argue that in these galaxies the continuum emission has probably a stellar origin. Finally in many cases we observe nearby faint objects close to the radio sources. The number density of these faint objects is slightly higher than what is found in the deep NICMOS parallel observations of random fields. These objects also tend to be aligned with the radio sources axis, suggesting that they may be related to the presence of the AGN. (shortened astro-ph version)Comment: To appear in ApJ

    HST images and properties of the most distant radio galaxies

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    We present Hubble Space Telescope images of 11 high redshift radio galaxies (between z=2.3z=2.3 and z=3.6z=3.6). The galaxies were observed with the WFPC2 camera in a broad band filter (F606W or F707W, roughly equivalent to V or R-band), for 2 orbits each. We find that on the scale of the HST observations there is a wide variety of morphological structures of the hosting galaxies: most objects have a clumpy, irregular appearance, consisting of a bright nucleus and a number of smaller components, suggestive of merging systems. Some observed structures could be due (at least partly) to the presence of dust distributed through the galaxies. The UV continuum emission is generally elongated and aligned with the axis of the radio sources, however the characteristics of the ``alignment effect'' differ from case to case, suggesting that the phenomenon cannot be explained by a single physical mechanism. We compare the properties of our radio galaxies with those of the UV dropout galaxies and conclude that (i) the most massive radio galaxies may well evolve from an aggregate of UV dropout galaxies and (ii) high redshift radio galaxies probably evolve into present day brightest cluster galaxies.Comment: 22 pages, 30 figures, accepted by A&
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