188 research outputs found
Faint dwarf galaxies in the Next Generation Virgo cluster Survey
The Next Generation Virgo Cluster Survey (NGVS) is a CFHT Large Program that
is using the wide field of view capabilities of the MegaCam camera to map the
entire Virgo Cluster from its core to virial radius. The observing strategy has
been optimized to detect very low surface brightness structures in the cluster,
including intracluster stellar streams and faint dwarf spheroidal galaxies. We
present here the current status of this ongoing survey, with an emphasis on the
detection and analysis of the very low-mass galaxies in the cluster that have
been revealed by the NGVS.Comment: 6 pages, 2 figures, Conference Proceedings: "A Universe of Dwarf
Galaxies", 14-18 June 2010, Lyon, Franc
Midwives’ perspectives of continuity based working in the UK: A cross-sectional survey
Objective: UK policy is advocating continuity of midwife throughout the antenatal, intrapartum and postnatal period in order to improve outcomes. We explored the working patterns that midwives are willing and able to adopt, barriers to change, and what would help midwives to work in continuity models of care.Design: A cross-sectional survey.Setting: 27 English maternity providers in the seven geographically-based ‘Early Adopter’ sites, which have been chosen to fast-track national policy implementation. Participants: All midwives working in the ‘Early Adopter’ sites were eligible to take part.Method: Anonymous online survey disseminated by local and national leaders, and social media, in October 2017. Descriptive statistics were calculated for quantitative survey responses. Qualitative free text responses were analysed thematically.Findings: 798 midwives participated (estimated response rate 20% calculated using local and national NHS workforce headcount data for participating sites). Being willing or able to work in a continuity model (caseloading and/or team)was lowest where this included intrapartum care in both hospital and home settings (35%, n = 279). Willingness to work in a continuity model of care increased as the range of intrapartum care settings covered decreased (home births only 45%, n = 359; no intrapartum care at all 54%, n = 426). A need to work on the same day each week was reported by 24% (n = 188). 31% (n = 246) were currently working 12 h shifts only, while 37% (n = 295) reported being unable to work any on-calls and/or nights. Qualitative analysis revealed multiple barriers to working in continuity models: the most prominent was caring responsibilities for children and others. Midwives suggested a range of approaches to facilitate working differently including concessions in the way midwife roles are organised, such as greater autonomy and choice in working patterns.Conclusions: Findings suggest that many midwives are not currently able or willing to work in continuity models, which includes care across antenatal, intrapartum and postnatal periods as recommended by UK policy.Implications for Practice: A range of approaches to providing continuity models should be explored as the implementation of ‘Better Births’ takes place across England. This should include studies of the impact of the different models on women, babies and midwives, along with their practical scalability and cost
Bridging Science with Society: Defining Pathways for Engagement
Science communication training organizations, are uniquely positioned at the nexus of science and society. Through research and training, they empower scientists to engage with the public to ultimately improve how science informs decision-making processes at the individual, organizational, and community levels. This paper argues that science communication training organizations must unite to provide a comprehensive and exhaustive set of offerings that empower scientists to master foundational communication skills while recognizing the complete social and cultural systems in which their science communication occurs. We present three separate possible pathways training programs could take, depending on the contexts and audiences for engagement. We differentiate between the goals, sites, and audiences for engagement, and the forms of knowledge or preparation needed for productive engagement
The Next Generation Virgo Cluster Survey. XII. Stellar Populations and Kinematics of Compact, Low-Mass Early-Type Galaxies from Gemini GMOS-IFU Spectroscopy
We present Gemini GMOS-IFU data of eight compact low-mass early-type galaxies
(ETGs) in the Virgo cluster. We analyse their stellar kinematics, stellar
population, and present two-dimensional maps of these properties covering the
central 5"x 7" region. We find a large variety of kinematics: from non- to
highly-rotating objects, often associated with underlying disky isophotes
revealed by deep images from the Next Generation Virgo Cluster Survey. In half
of our objects, we find a centrally-concentrated younger and more metal-rich
stellar population. We analyze the specific stellar angular momentum through
the lambdaR parameter and find six fast-rotators and two slow-rotators, one
having a thin counter-rotating disk. We compare the local galaxy density and
stellar populations of our objects with those of 39 more extended low-mass
Virgo ETGs from the SMAKCED survey and 260 massive (\Msun) ETGs from
the A3D sample. The compact low-mass ETGs in our sample are located in high
density regions, often close to a massive galaxy and have, on average, older
and more metal-rich stellar populations than less compact low-mass galaxies. We
find that the stellar population parameters follow lines of constant velocity
dispersion in the mass-size plane, smoothly extending the comparable trends
found for massive ETGs. Our study supports a scenario where low-mass compact
ETGs have experienced long-lived interactions with their environment, including
ram-pressure stripping and gravitational tidal forces, that may be responsible
for their compact nature.Comment: Accepted in ApJ, 19 pages, 10 figure
Qualitative evaluation of web-based digital intervention to prevent and reduce excessive alcohol use and harm among young people age 14-15 years:A ‘Think-Aloud’ study
BACKGROUND: In the United Kingdom, despite some downward trends in alcohol use among young people, over one-fifth of young people reported excessive alcohol use in the past month, which is associated with short- and long-term harm to health. Digital interventions to reduce alcohol use, such as websites, among young people present an appealing and cost-effective mode of intervention that can be integrated into the education system. However, relatively few school-based digital alcohol-focused interventions have been developed and evaluated for young people in the United Kingdom. OBJECTIVE: This study aims to develop a novel web-based intervention, Rethink Alcohol, to prevent and reduce excessive alcohol use and related harm among young people aged between 14 and 15 years, and explore the views of young people, teachers, and youth workers in relation to the content, design, and usability of the intervention. METHODS: Intervention development followed the person-based approach, using theories of social norms and social influence. Qualitative "Think-Aloud" interviews, either one-to-one or paired, were conducted while participants perused and worked through the web-based intervention, talking aloud. Participants included 20 young people (12 female, 8 male), 5 youth workers (4 female, 1 male), 3 teachers (2 male, 1 female), and 1 (male) clinical professional, recruited via youth groups and professional networks. Interviews were audio recorded, transcribed verbatim, and analyzed thematically. RESULTS: The prototype web-based intervention included normative feedback, information, a quiz, interactive activities, and scenarios. On a rating scale of impressions from poor (1) to excellent (5), participants gave an average score of 3.6/5. A total of 5 themes were identified: content, credibility of the website, making the website easy to understand, design and navigation, and suitability for the audience. These themes reflected views that the content was interesting, credible, informative, and embodied a neutral and nonjudgmental tone, but stronger messaging was needed regarding social pressures and short-term risks regarding safety and risk behavior alongside clarity around pathways of risk; credibility and trustworthiness of information were critical features, determined in part, by the professionalism of design and referencing of sources of information provided; and messages should be succinct and come to life through design and interactive features. CONCLUSIONS: Together, the data illustrated the importance and challenge of communicating nuanced alcohol-focused public health messages to young people in concise, clear, nonjudgmental, and appealing ways. Young people report interest in clear, credible, neutral, and interactive messages regarding social pressures and short-term risks of alcohol use via a web-based intervention. There is scope for optimization and feasibility testing of the Rethink Alcohol intervention
The Next Generation Virgo Cluster Survey. IX. Estimating the Efficiency of Galaxy Formation on the Lowest-Mass Scales
The Next Generation Virgo Cluster Survey has recently determined the
luminosity function of galaxies in the core of the Virgo cluster down to
unprecedented magnitude and surface brightness limits. Comparing simulations of
cluster formation to the derived central stellar mass function, we attempt to
estimate the stellar-to-halo-mass ratio (SHMR) for dwarf galaxies, as it would
have been before they fell into the cluster. This approach ignores several
details and complications, e.g., the contribution of ongoing star formation to
the present-day stellar mass of cluster members, and the effects of adiabatic
contraction and/or violent feedback on the subhalo and cluster potentials. The
final results are startlingly simple, however; we find that the trends in the
SHMR determined previously for bright galaxies appear to extend down in a
scale-invariant way to the faintest objects detected in the survey. These
results extend measurements of the formation efficiency of field galaxies by
two decades in halo mass, or five decades in stellar mass, down to some of the
least massive dwarf galaxies known, with stellar masses of .Comment: 18 pages, 12 figures; published in ApJ July 1st 201
The Next Generation Virgo Cluster Survey. X. Properties of Ultra-Compact Dwarfs in the M87, M49 and M60 Regions
We use imaging from the Next Generation Virgo cluster Survey (NGVS) to
present a comparative study of ultra-compact dwarf (UCD) galaxies associated
with three prominent Virgo sub-clusters: those centered on the massive,
red-sequence galaxies M87, M49 and M60. We show how UCDs can be selected with
high completeness using a combination of half-light radius and location in
color-color diagrams ( or ). Although the central galaxies in
each of these sub-clusters have nearly identical luminosities and stellar
masses, we find large differences in the sizes of their UCD populations, with
M87 containing ~3.5 and 7.8 times more UCDs than M49 and M60, respectively. The
relative abundance of UCDs in the three regions scales in proportion to
sub-cluster mass, as traced by X-ray gas mass, total gravitating mass, number
of globular clusters, and number of nearby galaxies. We find that the UCDs are
predominantly blue in color, with ~85% of the UCDs having colors similar to
blue GCs and stellar nuclei of dwarf galaxies. We present evidence that UCDs
surrounding M87 and M49 may follow a morphological sequence ordered by the
prominence of their outer, low surface brightness envelope, ultimately merging
with the sequence of nucleated low-mass galaxies, and that envelope prominence
correlates with distance from either galaxy. Our analysis provides evidence
that tidal stripping of nucleated galaxies is an important process in the
formation of UCDs.Comment: 37 pages, 40 figures. To appear in The Astrophysical Journa
The Next Generation Virgo Cluster Survey - Infrared (NGVS-IR): I. A new Near-UV/Optical/Near-IR Globular Cluster selection tool
The NGVS-IR project (Next Generation Virgo Survey - Infrared) is a contiguous
near-infrared imaging survey of the Virgo cluster of galaxies. It complements
the optical wide-field survey of Virgo (NGVS). The current state of NGVS-IR
consists of Ks-band imaging of 4 deg^2 centered on M87, and J and Ks-band
imaging of 16 deg^2 covering the region between M49 and M87. In this paper, we
present the observations of the central 4 deg^2 centered on Virgo's core
region. The data were acquired with WIRCam on the Canada-France-Hawaii
Telescope and the total integration time was 41 hours distributed in 34
contiguous tiles. A survey-specific strategy was designed to account for
extended galaxies while still measuring accurate sky brightness within the
survey area. The average 5\sigma limiting magnitude is Ks=24.4 AB mag and the
50% completeness limit is Ks=23.75 AB mag for point source detections, when
using only images with better than 0.7" seeing (median seeing 0.54"). Star
clusters are marginally resolved in these image stacks, and Virgo galaxies with
\mu_Ks=24.4 AB mag arcsec^-2 are detected. Combining the Ks data with optical
and ultraviolet data, we build the uiK color-color diagram which allows a very
clean color-based selection of globular clusters in Virgo. This diagnostic plot
will provide reliable globular cluster candidates for spectroscopic follow-up
campaigns needed to continue the exploration of Virgo's photometric and
kinematic sub-structures, and will help the design of future searches for
globular clusters in extragalactic systems. Equipped with this powerful new
tool, future NGVS-IR investigations based on the uiK diagram will address the
mapping and analysis of extended structures and compact stellar systems in and
around Virgo galaxies.Comment: 23 pages, 18 figures. Accepted for publication in ApJ
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