89 research outputs found
Abundance ratios in the hot ISM of elliptical galaxies
To constrain the recipes put forth to solve the theoretical Fe discrepancy in
the hot interstellar medium of elliptical galaxies and at the same time explain
the [alpha/Fe] ratios. In order to do so we use the latest theoretical
nucleosynthetic yields, we incorporate the dust, we explore differing SNIa
progenitor scenarios by means of a self-consistent chemical evolution model
which reproduces the properties of the stellar populations in elliptical
galaxies. Models with Fe-only dust and/or a lower effective SNIa rate achieve a
better agreement with the observed Fe abundance. However, a suitable
modification to the SNIa yield with respect to the standard W7 model is needed
to fully match the abundance ratio pattern. The 2D explosion model C-DDT by
Maeda et al. (2010) is a promising candidate for reproducing the [Fe/H] and the
[alpha/Fe] ratios. (A&A format)Comment: 11 pages, 4 figures, to appear on A&
X-ray Properties of Young Early Type Galaxies: II. Abundance Ratio in the Hot ISM
Using Chandra X-ray observations of young, post-merger elliptical galaxies,
we present X-ray characteristics of age-related observational results, by
comparing with typical old elliptical galaxies in terms of metal abundances in
the hot interstellar matter (ISM). While the absolute element abundances may be
uncertain because of unknown systematic errors and partly because of the
smaller amount of hot gas in young ellipticals, the relative abundance ratios
(e.g., the alpha-element to Fe ratio, most importantly Si/Fe ratio) can be
relatively well constrained. We find that in two young elliptical galaxies (NGC
720 and NGC 3923) the Si to Fe abundance ratio is super-solar (at a 99%
significance level), in contrast to typical old elliptical galaxies where the
Si to Fe abundance ratio is close to solar. Also the O/Mg ratio is close to
solar in the two young elliptical galaxies, as opposed to the sub-solar O/Mg
ratio reported in old elliptical galaxies. Both features appear to be less
significant outside the effective radius (roughly 30" for the galaxies under
study), consistent with the observations that confine to the centermost regions
the signatures of recent star formation in elliptical galaxies. Observed
differences between young and old elliptical galaxies can be explained by the
additional contribution from SNe II ejecta in the former. In young elliptical
galaxies, the later star formation associated with recent mergers would have a
dual effect, resulting both in galaxy scale winds - and therefore smaller
observed amounts of hot ISM - because of the additional SNII heating, and in
different metal abundances, because of the additional SNII yields.Comment: 21 pages, 4 color figures, ApJ in press, minor revisions for
referee's comments, a new figure adde
Composite structural motifs of binding sites for delineating biological functions of proteins
Most biological processes are described as a series of interactions between
proteins and other molecules, and interactions are in turn described in terms
of atomic structures. To annotate protein functions as sets of interaction
states at atomic resolution, and thereby to better understand the relation
between protein interactions and biological functions, we conducted exhaustive
all-against-all atomic structure comparisons of all known binding sites for
ligands including small molecules, proteins and nucleic acids, and identified
recurring elementary motifs. By integrating the elementary motifs associated
with each subunit, we defined composite motifs which represent
context-dependent combinations of elementary motifs. It is demonstrated that
function similarity can be better inferred from composite motif similarity
compared to the similarity of protein sequences or of individual binding sites.
By integrating the composite motifs associated with each protein function, we
define meta-composite motifs each of which is regarded as a time-independent
diagrammatic representation of a biological process. It is shown that
meta-composite motifs provide richer annotations of biological processes than
sequence clusters. The present results serve as a basis for bridging atomic
structures to higher-order biological phenomena by classification and
integration of binding site structures.Comment: 34 pages, 7 figure
Computational geometry analysis of dendritic spines by structured illumination microscopy
We are currently short of methods that can extract objective parameters of dendritic spines useful for their categorization. Authors present in this study an automatic analytical pipeline for spine geometry using 3D-structured illumination microscopy, which can effectively extract many geometrical parameters of dendritic spines without bias and automatically categorize spine population based on their morphological feature
Vision and visual history in elite-/near-elite level cricketers and rugby-league players
Background: The importance of optimal and/or superior vision for participation in high-level sport remains the subject of considerable clinical research interest. Here we examine the vision and visual history of elite/near-elite cricketers and rugby-league players.
Methods: Stereoacuity (TNO), colour vision, and distance (with/without pinhole) and near visual acuity (VA) were measured in two cricket squads (elite/international-level, female, n=16; near-elite, male, n=23) and one professional rugby-league squad (male, n=20). Refractive error was determined, and details of any correction worn and visual history were recorded.
Results: Overall, 63% had their last eye-examination within 2 years. However, some had not had an eye examination for 5 years, or had never had one (near-elite-cricketers: 30%; rugby-league players: 15%; elite-cricketers: 6%). Comparing our results for all participants to published data for young, optimally-corrected, non-sporting adults, distance VA was ~1 line of letters worse than expected. Adopting α=0.01, the deficit in distance-VA deficit was significant, but only for elite-cricketers (p0.02 for all comparisons). On average, stereoacuity was better than in young adults, but only in elite-cricketers (p<0.001; p=0.03, near-elite-cricketers; p=0.47, rugby-league -players). On-field visual issues were present in 27% of participants, and mostly (in 75% of cases) comprised uncorrected ametropia. Some cricketers (near-elite: 17.4%; elite: 38%) wore refractive correction during play but no rugby-league player did. Some individuals with prescribed correction choose not to wear it when playing.
Conclusion: Aside from near stereoacuity in elite-cricketers, these basic visual abilities were not better than equivalent, published data for optimally-corrected adults. 20-25% exhibited sub-optimal vision, suggesting that the clearest possible vision might not be critical for participation at the highest levels in the sports of cricket or rugby-league. Although vision could be improved in a sizeable proportion of our sample, the impact of correcting these, mostly subtle, refractive anomalies on playing performance is unknown
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Motives and comprehension in a public goods game with induced emotions
This study analyses the sensitivity of public goods contributions through the lens of psychological motives. We report the results of a public goods experiment in which subjects were induced with the motives of care and anger through autobiographical recall. Subjects' preferences, beliefs, and perceptions under each motive are compared with those of subjects experiencing a neutral autobiographical recall control condition. We find, but only for those subjects with the highest comprehension of the game, that care elicits significantly higher contributions than anger, with the control treatment in between. This positive influence of the care motive on unconditional giving is accounted for partly by preferences for giving and partly by the beliefs concerning greater contributions by others. Anger also affects attention to own and other's payoffs (using mouse tracking) and perceptions of the game's incentive structure (cooperative or competitive)
Busy doing nothing? What do players do in idle games?
Idle games – games where waiting for extended periods is an important dynamic – are increasing in popularity. The game Neko Atsume, a mobile game about collecting cats, is an extreme example of this genre where progress can only be achieved when the game is switched off (so-called "progress while gone"). Do such waiting games engage players? To answer this, we conducted a large survey (N=1972) to understand what players are doing when they play Neko Atsume. Players are highly “engaged” in Neko Atsume as they interact with and around the game in four distinct ways: Time spent playing, Direct sociability; Social media sociability and Checking frequency. However, these characteristics of engagement in Neko Atsume do not fit well with existing models of engagement. We propose that, in future studies, game engagement in idle games could be considered as a habit which players acquire and maintain
Dark Matter in the Milky Way's Dwarf Spheroidal Satellites
The Milky Way's dwarf spheroidal satellites include the nearest, smallest and
least luminous galaxies known. They also exhibit the largest discrepancies
between dynamical and luminous masses. This article reviews the development of
empirical constraints on the structure and kinematics of dSph stellar
populations and discusses how this phenomenology translates into constraints on
the amount and distribution of dark matter within dSphs. Some implications for
cosmology and the particle nature of dark matter are discussed, and some
topics/questions for future study are identified.Comment: A version with full-resolution figures is available at
http://www.cfa.harvard.edu/~mwalker/mwdsph_review.pdf; 70 pages, 22 figures;
invited review article to be published in Vol. 5 of the book "Planets, Stars,
and Stellar Systems", published by Springe
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