Action-space clustering of tidal streams to infer the Galactic potential

We present a new method for constraining the Milky Way halo gravitational potential by simultaneously fitting multiple tidal streams. This method requires full three-dimensional positions and velocities for all stars to be fit, but does not require identification of any specific stream or determination of stream membership for any star. We exploit the principle that the action distribution of stream stars is most clustered when the potential used to calculate the actions is closest to the true potential. Clustering is quantified with the Kullback-Leibler Divergence (KLD), which also provides conditional uncertainties for our parameter estimates. We show, for toy Gaia-like data in a spherical isochrone potential, that maximizing the KLD of the action distribution relative to a smoother distribution recovers the true values of the potential parameters. The precision depends on the observational errors and the number of streams in the sample; using KIII giants as tracers, we measure the enclosed mass at the average radius of the sample stars accurate to 3% and precise to 20-40%. Recovery of the scale radius is precise to 25%, and is biased 50% high by the small galactocentric distance range of stars in our mock sample (1-25 kpc, or about three scale radii, with mean 6.5 kpc). About 15 streams, with at least 100 stars per stream, are needed to obtain upper and lower bounds on the enclosed mass and scale radius when observational errors are taken into account; 20-25 streams are required to stabilize the size of the confidence interval. If radial velocities are provided for stars out to 100 kpc (10 scale radii), all parameters can be determined with 10% accuracy and 20% precision (1.3% accuracy in the case of the enclosed mass), underlining the need for ground-based spectroscopic follow-up to complete the radial velocity catalog for faint halo stars observed by Gaia.Comment: Accepted versio

The dependence on morphology of the gas content in galactic disks

The classification S0 was introduced by Hubble to serve as a description of galaxies whose morphological characteristics seemed to lie between the disk-dominated spirals and the spheroidal elliptical systems. Since then there has been extensive discussion as to whether this classification sequence is also an evolutionary sequence. Many studies have focussed on a particular feature such as the luminosity profile, the bulge-to-disk ratio, or the nature of the interstellar matter, but the question of the evolution remains contentious. Equally contentious is the question of the classification itself. For systems with well-developed disks there usually is no problem. Many spheroidal systems also are unambiguously classified as ellipticals in most catalogs. However, there are a number of early systems which have been reclassified following review using improved optical material. For example, Eder et al. (AJ, 102, 572, 1991) found that many of the S0 galaxies which are rich in neutral hydrogen have faint spiral features. The confusion about classification propagates into the discussion of the properties of early-type systems. Attempts to put the classification system on a quantitative basis have in general been unsuccessful. Recently Sandage (private communication) has reviewed the classification of early systems and has defined a set of sub-classes for these objects. The S0 galaxies are divided into three groups, depending on the prominence of the disk. There are six subdivisions of Sa galaxies, depending upon the relative prominence of knots and other arm-like characteristics. We have explored the total gas content in these objects to see if there is a dependence on the galaxy morphology, as denoted by these new subclasses

What mattered ten years on? Young people’s reflections on their involvement with a charitable youth participation project

Youth work in England is experiencing ongoing rapid and significant change, fuelling debate about its very function. This paper contributes to this debate by presenting original research on what young people themselves prioritised as significant in-service provision and highlights the longer-term impact that engagement with a voluntary sector organisation can have on the lives of vulnerable young people. Drawing on qualitative interviews with ten former youth participants involved in youth participation projects, the findings presented in this paper suggest that participants felt the support they received was, in many cases, ‘transformative’. However, they primarily defined their experiences and the impact through their relationships with individuals supporting them, through the sense of achievement and ability to effect change they developed and through finding a voice to affect community decisions

A List of Wisconsin Springtails With New Records and Annotations (Hexapoda: Parainsecta: Collembola)

Twenty Collembola species new to Wisconsin were collected from soil at two agricultural sites in southern Wisconsin, including an undescribed species of Isotomidae. The state faunal list now contains 52 species representing seven families

An Examination of the Volitional Stages in Consumer Decisions to Avoid Sweatshop Clothing

While much research in ethical consumption has focused on contexts such as food, this research explores ethical consumer decision-making in the context of intention to avoid sweatshop clothing where consumer concern has increased but response from the market remains limited. This research seeks to deepen the theory of planned behaviour with respect to the volitional stages underlying behaviour. The findings of the research support a modified theory of planned behaviour model and also reveal volitional stages from intention to trying and plan which reveal the stages of consumer decision-making to avoid sweatshop clothing. Implications for consumer decision-making are discussed

Intending to be ethical: An examination of consumer choice in sweatshop avoidance

While much research in ethical consumption has focused on contexts such as food, this research explores ethical consumer decision-making in the context of intention to avoid sweatshop apparel. This research seeks to deepen the Theory of Planned Behavior with respect to the motivation and volitional stages underlying behavior. The findings of the research, based on 794 consumers, are novel and support an enriched framework which reveals that the role of attitude, subjective norm and perceived behavioral control are mediated by desire, intention and plan. The findings have implications for research seeking to address the ‘intention-behavior’ gap

A survey of the properties of early-type galaxies

A compilation of the properties of elliptical and early disk galaxies was completed. In addition to material from the literature, such as Infrared Astronomy Satellite (IRAS) fluxes, the compilation includes recent measurements of HI and CO, as well as a review of the x ray properties by Forman and Jones. The data are used to evaluate the gas content of early systems and to search for correlations with x ray emission. The interstellar medium in early-type galaxies is generally dominated by hot interstellar gas (T approx. 10 to the 7th power K; c.f. the review by Fabbiano 1989 and references therein). In addition, a significant fraction of these galaxies show infrared emission (Knapp, et al., 1989), optical emission lines, and visible dust. Sensitive studies in HI and CO of a number of these galaxies have been completed recently, resulting in several detections, particularly of the later types. Researchers wish to understand the connection among these different forms of the interstellar medium, and to examine the theoretical picture of the fate of the hot gas. To do so, they compiled observations of several forms of interstellar matter for a well-defined sample of early-type galaxies. Here they present a statistical analysis of this data base and discuss the implications of the results

To bridge the gap: voluntary action in primary education

Voluntary action has had a long history in the education of our children, bringing a wide range of positive benefits to schools, children, staff, the local community and volunteers alike. Voluntary action enables schools to draw upon a wide range of additional skills and resources, can strengthen a school community and engage children in philanthropic activity from an early age. Schools continuously highlight how much they value the commitment, passion, skills and expertise brought into their community by volunteers, and recognise the advantages of fundraising in terms of community engagement, fostering philanthropic activity in children and providing additional income for the school. Unsurprisingly voluntary action in education tends to be viewed as a positive and good thing, and is increasingly encouraged within policy and practice. This research suggests that voluntary action in primary schools is indeed becoming progressively central to school activities, with many primary schools keenly seeking to strategically engage and grow this area of activity. Schools report purposefully fostering engagement of volunteers to help increase teacher capacity, support children through one-to-one activities and provide additional resources for both core and extra-curricular activities. Furthermore, schools highlight increasing focus on their fundraising activities to help support depleting budgets and growing demands. There is however very little research in the UK which explores voluntary action in education. The limited research that is available suggests significant disparities in how additional resources from voluntary action are dispersed within the UK context. This is supported by research from across Europe and the United States. Therefore this project sets out to be an exploratory study of this area to ascertain how actively schools engage with this voluntary action and what barriers they may face. The local authority of Kent was chosen as a focus for this study. Through analysis of financial data of over 600 primary schools, questionnaires completed by 114 of these and interviews with 4 case study schools this research presents initial findings and trends in activity under the separate headings of volunteering and philanthropic activity (fundraising)

Feature space analysis for human activity recognition in smart environments

Activity classification from smart environment data is typically done employing ad hoc solutions customised to the particular dataset at hand. In this work we introduce a general purpose collection of features for recognising human activities across datasets of different type, size and nature. The first experimental test of our feature collection achieves state of the art results on well known datasets, and we provide a feature importance analysis in order to compare the potential relevance of features for activity classification in different datasets