670 research outputs found
Comparison of owner-reported behavioral characteristics among genetically clustered breeds of dog (Canis familiaris).
During the domestication process, dogs were selected for their suitability for multiple purposes, resulting in a variety of behavioral characteristics. In particular, the ancient group of breeds that is genetically closer to wolves may show different behavioral characteristics when compared to other breed groups. Here, we used questionnaire evaluations of dog behavior to investigate whether behavioral characteristics of dogs were different among genetically clustered breed groups. A standardized questionnaire, the Canine Behavioral Assessment and Research Questionnaire (C-BARQ), was used, and breed group differences of privately-owned dogs from Japan (n = 2,951) and the United States (n = 10,389) were analyzed. Results indicated that dogs in the ancient and spitz breed group showed low attachment and attention-seeking behavior. This characteristic distinguished the ancient group from any other breed groups with presumed modern European origins, and may therefore, be an ancestral trait
Searches for New Milky Way Satellites from the First Two Years of Data of the Subaru/Hyper Suprime-Cam Survey: Discovery of Cetus~III
We present the results from a search for new Milky Way (MW) satellites from
the first two years of data from the Hyper Suprime-Cam (HSC) Subaru Strategic
Program (SSP) ~deg and report the discovery of a highly
compelling ultra-faint dwarf galaxy candidate in Cetus. This is the second
ultra-faint dwarf we have discovered after Virgo~I reported in our previous
paper. This satellite, Cetus~III, has been identified as a statistically
significant (10.7) spatial overdensity of star-like objects, which are
selected from a relevant isochrone filter designed for a metal-poor and old
stellar population. This stellar system is located at a heliocentric distance
of 251~kpc with a most likely absolute magnitude of ~mag estimated from a Monte Carlo analysis. Cetus~III is extended with
a half-light radius of ~pc, suggesting that this is a
faint dwarf satellite in the MW located beyond the detection limit of the Sloan
Digital Sky Survey. Further spectroscopic studies are needed to assess the
nature of this stellar system. We also revisit and update the parameters for
Virgo~I finding ~mag and ~pc. Using simulations of -dominated cold dark matter
models, we predict that we should find one or two new MW satellites from ~deg HSC-SSP data, in rough agreement with the discovery rate so far.
The further survey and completion of HSC-SSP over ~deg will
provide robust insights into the missing satellites problem.Comment: 12 pages, 12 figures, accepted for publication in PASJ special issu
Descendants of the first stars: the distinct chemical signature of second generation stars
Extremely metal-poor (EMP) stars in the Milky Way (MW) allow us to infer the
properties of their progenitors by comparing their chemical composition to the
metal yields of the first supernovae. This method is most powerful when applied
to mono-enriched stars, i.e. stars that formed from gas that was enriched by
only one previous supernova. We present a novel diagnostic to identify this
subclass of EMP stars. We model the first generations of star formation
semi-analytically, based on dark matter halo merger trees that yield MW-like
halos at the present day. Radiative and chemical feedback are included
self-consistently and we trace all elements up to zinc. Mono-enriched stars
account for only of second generation stars in our fiducial model
and we provide an analytical formula for this probability. We also present a
novel analytical diagnostic to identify mono-enriched stars, based on the metal
yields of the first supernovae. This new diagnostic allows us to derive our
main results independently from the specific assumptions made regarding Pop III
star formation, and we apply it to a set of observed EMP stars to demonstrate
its strengths and limitations. Our results may provide selection criteria for
current and future surveys and therefore contribute to a deeper understanding
of EMP stars and their progenitors.Comment: 18 pages, 20 figures, published in MNRA
Do bilinguals have different concepts? The case of shape and material in Japanese L2 users of English
An experiment investigated whether Japanese speakers’ categorisation of objects and substances as shape or material is influenced by acquiring English, based on Imai and Gentner (1997). Subjects were presented with an item such as a cork pyramid and asked to choose between two other items that matched it for shape (plastic pyramid) or for material (piece of cork). The hypotheses were that for simple objects the number of shape-based categorisations would increase according to experience of English and that the preference for shape and material-based categorisations of Japanese speakers of English would differ from mono¬lingual speakers of both languages. Subjects were 18 adult Japanese users of English who had lived in English-speaking countries between 6 months and 3 years (short-stay group), and 18 who had lived in English-speaking countries for 3 years or more (long-stay group). Both groups achieved above criterion on an English vocabulary test. Results were: both groups preferred material responses for simple objects and substances but not for complex objects, in line with Japanese mono¬linguals, but the long-stay group showed more shape preference than the short-stay group and also were less different from Americans. These effects of acquiring a second language on categorisation have implications for conceptual representation and methodology
A New Milky Way Satellite Discovered In The Subaru/Hyper Suprime-Cam Survey
We report the discovery of a new ultra-faint dwarf satellite companion of the
Milky Way based on the early survey data from the Hyper Suprime-Cam Subaru
Strategic Program. This new satellite, Virgo I, which is located in the
constellation of Virgo, has been identified as a statistically significant (5.5
sigma) spatial overdensity of star-like objects with a well-defined main
sequence and red giant branch in their color-magnitude diagram. The
significance of this overdensity increases to 10.8 sigma when the relevant
isochrone filter is adopted for the search. Based on the distribution of the
stars around the likely main sequence turn-off at r ~ 24 mag, the distance to
Virgo I is estimated as 87 kpc, and its most likely absolute magnitude
calculated from a Monte Carlo analysis is M_V = -0.8 +/- 0.9 mag. This stellar
system has an extended spatial distribution with a half-light radius of 38
+12/-11 pc, which clearly distinguishes it from a globular cluster with
comparable luminosity. Thus, Virgo I is one of the faintest dwarf satellites
known and is located beyond the reach of the Sloan Digital Sky Survey. This
demonstrates the power of this survey program to identify very faint dwarf
satellites. This discovery of VirgoI is based only on about 100 square degrees
of data, thus a large number of faint dwarf satellites are likely to exist in
the outer halo of the Milky Way.Comment: typos are corrected, 6 pages, 4 figures, accepted for publication in
Ap
Long-term monitoring of the short period SU UMa-type dwarf nova, V844 Herculis
We report on time-resolved CCD photometry of four outbursts of a short-period
SU UMa-type dwarf nova, V844 Herculis. We successfully determined the mean
superhump periods to be 0.05584(64) days, and 0.055883(3) for the 2002 May
superoutburst, and the 2006 April-May superoutburst, respectively. During the
2002 October observations, we confirmed that the outburst is a normal outburst,
which is the first recorded normal outburst in V844 Her. We also examined
superhump period changes during 2002 May and 2006 April-May superoutbursts,
both of which showed increasing superhump period over the course of the plateau
stage. In order to examine the long-term behavior of V844 Her, we analyzed
archival data over the past ten years since the discovery of this binary.
Although photometry is not satisfactory in some superoutbursts, we found that
V844 Her showed no precursors and rebrightenings. Based on the long-term light
curve, we further confirmed V844 Her has shown almost no normal outbursts
despite the fact that the supercycle of the system is estimated to be about 300
days. In order to explain the long-term light curves of V844 Her, evaporation
in the accretion disk may play a role in the avoidance of several normal
outbursts, which does not contradict with the relatively large X-ray luminosity
of V844 Her.Comment: 10 pages, 11 figures, accepted for PAS
A clinical tool for predicting survival in ALS
Background: Amyotrophic lateral sclerosis (ALS) is a progressive and usually fatal neurodegenerative disease. Survival from diagnosis varies considerably. Several prognostic factors are known, including site of onset (bulbar or limb), age at symptom onset, delay from onset to diagnosis and the use of riluzole and non-invasive ventilation (NIV). Clinicians and patients would benefit from a practical way of using these factors to provide an individualised prognosis.
Methods: 575 consecutive patients with incident ALS from a population-based registry in South-East England register for ALS (SEALS) were studied. Their survival was modelled as a two-step process: the time from diagnosis to respiratory muscle involvement, followed by the time from respiratory involvement to death. The effects of predictor variables were assessed separately for each time interval.
Findings: Younger age at symptom onset, longer delay from onset to diagnosis and riluzole use were associated with slower progression to respiratory involvement, and NIV use was associated with lower mortality after respiratory involvement, each with a clinically significant effect size. Riluzole may have a greater effect in younger patients and those with longer delay to diagnosis. A patient's survival time has a roughly 50% chance of falling between half and twice the predicted median.
Interpretation: A simple and clinically applicable graphical method of predicting an individual patient's survival from diagnosis is presented. The model should be validated in an independent cohort, and extended to include other important prognostic factors
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