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Understanding meaningful participation and the situated use of technology in community music for active ageing
AbstractAn unfortunate tendency in previous HCI research has been to give the impression that it aims to ‘fix the problem’ of human ageing, suggesting a ‘deficit’ model of ageing or a ‘prosthetic’ model of technology. We conducted diary-aided interviews to investigate how technology use is situated in active, healthy older adults’ meaningful participation in community music. We argue that recognizing community music practices and technology use as situated action provides opportunities to grasp the subtleties of social participation and design for active ageing. We identified technology-mediated music practices, such as music sharing and revisiting, and how they evolved through the reconfiguration of connections between technology, competence, and forward-facing identities. We found that identity development, via routes such as exercising control, role transitions, and social spaces, had psychological significance and implications for active ageing. We explore how HCI leverages the perspective of active ageing and might facilitate older adults’ meaningful participation enhanced by technologies.China Scholarship Counci
Observable Signatures of Planet Accretion in Red Giant Stars I: Rapid Rotation and Light Element Replenishment
The orbital angular momentum of a close-orbiting giant planet can be
sufficiently large that, if transferred to the envelope of the host star during
the red giant branch (RGB) evolution, it can spin-up the star's rotation to
unusually large speeds. This spin-up mechanism is one possible explanation for
the rapid rotators detected among the population of generally slow-rotating red
giant stars. These rapid rotators thus comprise a unique stellar sample
suitable for searching for signatures of planet accretion in the form of
unusual stellar abundances due to the dissemination of the accreted planet in
the stellar envelope. In this study, we look for signatures of replenishment in
the Li abundances and (to a lesser extent) 12C/13C, which are both normally
lowered during RGB evolution. Accurate abundances were measured from high
signal-to-noise echelle spectra for samples of both slow and rapid rotator red
giant stars. We find that the rapid rotators are on average enriched in lithium
compared to the slow rotators, but both groups of stars have identical
distributions of 12C/13C within our measurement precision. Both of these
abundance results are consistent with the accretion of planets of only a few
Jupiter masses. We also explore alternative scenarios for understanding the
most Li-rich stars in our sample---particularly Li regeneration during various
stages of stellar evolution. Finally, we find that our stellar samples show
non-standard abundances even at early RGB stages, suggesting that initial
protostellar Li abundances and 12C/13C may be more variable than originally
thought.Comment: Accepted for publication in the Astrophysical Journal. 29 pages in
emulateapj format, including 16 figures and 12 tables. Tables 4 and 8 are
provided in their entirety as plain text ancillary files (and will also be
available in the electronic edition of ApJ
Characterizing the Chemistry of the Milky Way Stellar Halo: Detailed Chemical Analysis of a Metal-Poor Stellar Stream
We present the results of a detailed abundance analysis of one of the
confirmed building blocks of the Milky Way stellar halo, a
kinematically-coherent metal-poor stellar stream. We have obtained high
resolution and high S/N spectra of 12 probable stream members using the MIKE
spectrograph on the Magellan-Clay Telescope at Las Campanas Observatory and the
2dCoude spectrograph on the Smith Telescope at McDonald Observatory. We have
derived abundances or upper limits for 51 species of 46 elements in each of
these stars. The stream members show a range of metallicity (-3.4 < [Fe/H] <
-1.5) but are otherwise chemically homogeneous, with the same star-to-star
dispersion in [X/Fe] as the rest of the halo. This implies that, in principle,
a significant fraction of the Milky Way stellar halo could have formed from
accreted systems like the stream. The stream stars show minimal evolution in
the alpha or Fe-group elements over the range of metallicity. This stream is
enriched with material produced by the main and weak components of the rapid
neutron-capture process and shows no evidence for enrichment by the slow
neutron-capture process.Comment: v2: Removed references to M15 after learning that the source
kinematic data for M15 were incorrect in an earlier paper. M15 is not related
to this stream. (ApJ, accepted; 31 pages, 18 figures, 11 tables
Precise radial velocities of giant stars. III. Spectroscopic stellar parameters
Context: A radial velocity survey of about 380 G and K giant stars is ongoing
at Lick observatory. For each star we have a high signal to noise ratio
template spectrum, which we use to determine spectroscopic stellar parameters.
Aim: The aim of this paper is to present spectroscopic stellar parameters, i.e.
effective temperature, surface gravity, metallicity and rotational velocity for
our sample of G and K giant stars. Methods: Effective temperatures, surface
gravities and metallicities are determined from the equivalent width of iron
lines. Rotational velocities are determined from the full width at half maximum
(FWHM) of moderate spectral lines. A calibration between the FWHM and total
broadening (rotational velocity and macro turbulence) is obtained from stars in
common between our sample and the sample from Gray (1989). Results: The
metallicity we derive is essentially equal to the literature values, while the
effective temperature and surface gravity are slightly higher by 56 K and 0.15
dex, respectively. Our rotational velocities are comparable with the ones
obtained by Gray (1989), but somewhat higher than the ones obtained by de
Medeiros & Mayor (1999), consistent with the different diagnostics used.
Conclusions: We are able to determine spectroscopic stellar parameters for
about 380 G and K giant stars in a uniform way (112 stars are being analysed
spectroscopically for the first time). For stars available in the literature,
we find reasonable agreement between literature values and values determined in
the present work. In addition, we show that the metallicity enhancement of
companion hosting stars might also be valid for giant stars, with the
planet-hosting giants being 0.13 +/- 0.03 dex (i.e. 35 +/- 10%) more metal-rich
than our total sample of stars.Comment: 16 pages, 8 figures, 4 tables, accepted for publication by Astronomy
and Astrophysic
Abundance Patterns in the Draco, Sextans and Ursa Minor Dwarf Spheroidal Galaxies
The Keck I telescope has been used to obtain HIRES spectra for red giants
belonging to the Draco, Sextans and Ursa Minor dwarf spheroidal (dSph)
galaxies. An analysis of these spectra is presented, along with abundance
ratios for more than 20 elements. The resulting database of element abundances
for 17 stars is the most extensive yet assembled for stars in dSph
environments. Our main findings are summarized as follows: (1) There is
unambiguous evidence for a large internal spread in metallicity in all three
galaxies: our program stars span a range of [Fe/H] = 1.53, 1.40 and 0.73 dex in
Draco, Sextans and Ursa Minor, respectively. (2) The abundance patterns among
the dSph stars are remarkably uniform, suggesting that all three galaxies have
similar nucleosynthetic histories. (3) A comparison of the measured abundance
ratios for our sample of dSph stars with published values for Galactic halo and
disk field stars suggests that the dSph galaxies have 0.02 < [alpha/Fe] < 0.13
dex, whereas the halo field star sample has [alpha/Fe] ~ 0.28 dex over the same
range in metallicity. (4) The most metal-rich dSph stars in our sample have
[Y/Fe] abundances which are significantly lower than those measured for halo
field stars of similar metallicity, while the measured [Ba/Eu] ratios for the
dSph stars suggest that the early chemical evolution of these galaxies was
dominated by the r-process. Taken together, these results suggest that the
Galactic halo is unlikely to have assembled, in its entirety, through the
disruption of dwarf galaxies similar to the low-luminosity dSphs studied here.
(ABRIDGED).Comment: 24 pages, 8 postscript figures (including 6 color figures). Accepted
for publication in the Astrophysical Journa
Simply imagining sunshine, lollipops and rainbows will not budge the bias: The role of ambiguity in interpretive bias modification
Imagery-based interpretive bias modification (CBM-I) involves repeatedly imagining scenarios that are initially ambiguous before being resolved as either positive or negative in the last word/s. While the presence of such ambiguity is assumed to be important to achieve change in selective interpretation, it is also possible that the act of repeatedly imagining positive or negative events could produce such change in the absence of ambiguity. The present study sought to examine whether the ambiguity in imagery-based CBM-I is necessary to elicit change in interpretive bias, or, if the emotional content of the imagined scenarios is sufficient to produce such change. An imagery-based CBM-I task was delivered to participants in one of four conditions, where the valence of imagined scenarios were either positive or negative, and the ambiguity of the scenario was either present (until the last word/s) or the ambiguity was absent (emotional valence was evident from the start). Results indicate that only those who received scenarios in which the ambiguity was present acquired an interpretive bias consistent with the emotional valence of the scenarios, suggesting that the act of imagining positive or negative events will only influence patterns of interpretation when the emotional ambiguity is a consistent feature
Adaptation, coordination, and local interactions via distributed approachability
This paper investigates the relation between cooperation, competition, and local interactions in large distributed multi-agent
systems. The main contribution is the game-theoretic problem formulation and solution approach based on the new framework
of distributed approachability, and the study of the convergence properties of the resulting game model. Approachability
theory is the theory of two-player repeated games with vector payoffs, and distributed approachability is here presented for
the first time as an extension to the case where we have a team of agents cooperating against a team of adversaries under local
information and interaction structure. The game model turns into a nonlinear differential inclusion, which after a proper design
of the control and disturbance policies, presents a consensus term and an exogenous adversarial input. Local interactions enter
in the model through a graph topology and the corresponding graph-Laplacian matrix. Given the above model, we turn the
original questions on cooperation, competition, and local interactions, into convergence properties of the differential inclusion.
In particular, we prove convergence and exponential convergence conditions around zero under general Markovian strategies.
We illustrate our results in the case of decentralized organizations with multiple decision-makers
CoRoT 105906206: a short-period and totally eclipsing binary with a Delta Scuti type pulsator
Eclipsing binary systems with pulsating components allow the determination of
several physical parameters of the stars, such as mass and radius, that, when
combined with the pulsation properties, can be used to constrain the modeling
of stellar interiors and evolution. Hereby, we present the results of the study
of CoRoT 105906206, an eclipsing binary system with a pulsating component
located in the CoRoT LRc02 field. The analysis of the CoRoT light curve was
complemented by high-resolution spectra from the Sandiford at McDonald
Observatory and FEROS at ESO spectrographs, which revealed a double-lined
spectroscopic binary. We used an iterative procedure to separate the
pulsation-induced photometric variations from the eclipse signals. First, a
Fourier analysis was used to identify the significant frequencies and
amplitudes due to pulsations. Second, after removing the contribution of the
pulsations from the light curve we applied the PIKAIA genetic-algorithm
approach to derive the best parameters that describe the orbital properties of
the system. The light curve cleaned for pulsations contains the partial eclipse
of the primary and the total eclipse of the secondary. The system has an
orbital period of about 3.694 days and is formed by a primary star with mass M1
= 2.25 +/- 0.04 solar masses, radius R1 = 4.24 +/- 0.02 solar radii, and
effective temperature Teff1 = 6750 +/- 150 K, and a secondary with M2 = 1.29
+/- 0.03 solar masses, R2 = 1.34 +/- 0.01 solar radii, and Teff2 = 6152 +/- 162
K. The best solution for the parameters was obtained by taking into account the
asymmetric modulation observed in the light curve, known as the O'Connell
effect, presumably caused by Doppler beaming. The analysis of the Fourier
spectrum revealed that the primary component has p-mode pulsations in the range
5-13 c/d, which are typical of Delta Scuti type stars.Comment: 11 pages, 8 figures, 3 table
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