6,885 research outputs found

    Working with the public: how an unusual museum enquiry turned into travels through time and space

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    Museum enquiries offer a unique opportunity to engage on a one-to-one level with members of the public. This paper covers an unusual enquiry from 2013 of an unknown tooth that was brought into Plymouth City Museum and Art Gallery for identification. We highlight how museum enquiries can engage with members of the public by involving them directly with original scientific research. The tooth was found in a garden in Plymouth with no associated data of about where it originated. We identified the tooth, and the enquirer researched the history of the house. The tooth gave the appearance of a sub-fossil so with the large number of Quaternary sites in Plymouth, together with the identification of the previous owner on the site, there were valid reasons to undertake testing of the tooth to determine its origin. Strontium (Sr) isotope analysis of the tooth was carried out to determine if the tooth was British and radiocarbon dating was undertaken to work out the age of the tooth. The 87Sr /86Sr of the leopard tooth gave a value of 0.716131, with Sr concentrations at 568ppm. This is a high concentration of Sr ppm relative to other British data, suggesting a non-British origin. The radiocarbon measurement was 187 ± 24 years BP (University of Oxford Radiocarbon Accelerator Unit reference OxA-30390). This places the tooth not in the Pleistocene, but between 1739 and 1787 AD. The site where the tooth was discovered was owned by the brother of Linnaeus Tripe who travelled across India and Burma. We argue that the results of this study demonstrate that this leopard tooth was originally from India or Burma, and brought into Britain by Tripe

    The mass of dwarf spheroidal galaxies and the missing satellite problem

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    We present the results from a suite of N-body simulations of the tidal stripping of two-component dwarf galaxies comprising some stars and dark matter. We show that recent kinematic data from the local group dwarf spheroidal (dSph) galaxies suggests that dSph galaxies must be sufficiently massive (109−101010^9 - 10^{10}M⊙_\odot) that tidal stripping is of little importance for the stars. We discuss the implications of these massive dSph galaxies for cosmology and galaxy formation.Comment: 4 pages, 1 figure, to appear in the proceedings of the IAUC198 "Near-Field Cosmology with Dwarf Elliptical Galaxies", H. Jerjen & B. Binggeli (eds.). Comments welcom

    The tidal stripping of satellites

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    We present an improved analytic calculation for the tidal radius of satellites and test our results against N-body simulations. The tidal radius in general depends upon four factors: the potential of the host galaxy, the potential of the satellite, the orbit of the satellite and {\it the orbit of the star within the satellite}. We demonstrate that this last point is critical and suggest using {\it three tidal radii} to cover the range of orbits of stars within the satellite. In this way we show explicitly that prograde star orbits will be more easily stripped than radial orbits; while radial orbits are more easily stripped than retrograde ones. This result has previously been established by several authors numerically, but can now be understood analytically. For point mass, power-law (which includes the isothermal sphere), and a restricted class of split power law potentials our solution is fully analytic. For more general potentials, we provide an equation which may be rapidly solved numerically. Over short times (\simlt 1-2 Gyrs ∌1\sim 1 satellite orbit), we find excellent agreement between our analytic and numerical models. Over longer times, star orbits within the satellite are transformed by the tidal field of the host galaxy. In a Hubble time, this causes a convergence of the three limiting tidal radii towards the prograde stripping radius. Beyond the prograde stripping radius, the velocity dispersion will be tangentially anisotropic.Comment: 10 pages, 5 figures. Final version accepted for publication in MNRAS. Some new fully analytic tidal radii have been added for power law density profiles (including the isothermal sphere) and some split power law

    Moderators, mediators and nonspecific predictors of outcome after cognitive rehabilitation of executive functions in a randomised controlled trial

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    Moderators, mediators and nonspecific predictors of treatment after cognitive rehabilitation of executive functions in a randomised controlled trial Objective: To explore moderators, mediators and nonspecific predictors of executive functioning after cognitive rehabilitation in a randomised controlled trial, comparing Goal Management Training (GMT) with an active psycho-educative control-intervention, in patients with chronic acquired brain injury. Methods: Seventy patients with executive dysfunction were randomly allocated to GMT (n = 33) or control (n = 37). Outcome measures were established by factor-analysis and included cognitive executive complaints, emotional dysregulation and psychological distress. Results: Higher age and IQ emerged as nonspecific predictors. Verbal memory and planning ability at baseline moderated cognitive executive complaints, while planning ability at six-month follow-up mediated all three outcome measures. Inhibitory cognitive control emerged as a unique GMT specific mediator. A general pattern regardless of intervention was identified; higher levels of self-reported cognitive—and executive–symptoms of emotional dysregulation and psychological distress at six-month follow-up mediated less improvement across outcome factors. Conclusions: The majority of treatment effects were nonspecific to intervention, probably underscoring the variables’ general contribution to outcome of cognitive rehabilitation interventions. Interventions targeting specific cognitive domains, such as attention or working memory, need to take into account the patients’ overall cognitive and emotional self-perceived functioning. Future studies should investigate the identified predictors further, and also consider other predictor candidates

    Identifying which septic patients have increased mortality risk using severity scores:a cohort study

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    Background: Early aggressive therapy can reduce the mortality associated with severe sepsis but this relies on prompt recognition, which is hindered by variation among published severity criteria. Our aim was to test the performance of different severity scores in predicting mortality among a cohort of hospital inpatients with sepsis. Methods: We anonymously linked routine outcome data to a cohort of prospectively identified adult hospital inpatients with sepsis, and used logistic regression to identify associations between mortality and demographic variables, clinical factors including blood culture results, and six sets of severity criteria. We calculated performance characteristics, including area under receiver operating characteristic curves (AUROC), of each set of severity criteria in predicting mortality. Results: Overall mortality was 19.4% (124/640) at 30 days after sepsis onset. In adjusted analysis, older age (odds ratio 5.79 (95% CI 2.87-11.70) for ≥80y versus <60y), having been admitted as an emergency (OR 3.91 (1.31-11.70) versus electively), and longer inpatient stay prior to sepsis onset (OR 2.90 (1.41-5.94) for >21d versus <4d), were associated with increased 30 day mortality. Being in a surgical or orthopaedic, versus medical, ward was associated with lower mortality (OR 0.47 (0.27-0.81) and 0.26 (0.11-0.63), respectively). Blood culture results (positive vs. negative) were not significantly association with mortality. All severity scores predicted mortality but performance varied. The CURB65 community-acquired pneumonia severity score had the best performance characteristics (sensitivity 81%, specificity 52%, positive predictive value 29%, negative predictive value 92%, for 30 day mortality), including having the largest AUROC curve (0.72, 95% CI 0.67-0.77). Conclusions: The CURB65 pneumonia severity score outperformed five other severity scores in predicting risk of death among a cohort of hospital inpatients with sepsis. The utility of the CURB65 score for risk-stratifying patients with sepsis in clinical practice will depend on replicating these findings in a validation cohort including patients with sepsis on admission to hospital

    Relationship continuity and emotional well-being in spouses of people with dementia

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    YesObjectives: Qualitative research has suggested that spousal experiences of discontinuity in their relationship with a person who has dementia (i.e. the relationship is experienced as radically changed) may contribute to heightened feelings of burden, entrapment, isolation, guilt and intolerance of behaviours that challenge. By contrast, continuity in the relationship may contribute to a greater sense of achievement and gratification from providing care. The present study served as a quantitative test of these suggestions. Method: A convenience sample of 71 spouses of people with dementia completed three questionnaires - the Zarit Burden Interview (ZBI), the Positive Aspects of Caregiving measure (PAC) and the Birmingham Relationship Continuity Measure (BRCM). Results: In accordance with the hypotheses, the experience of greater relationship continuity (higher BRCM scores) was correlated with fewer negative emotional reactions to caregiving (lower ZBI scores; rho = −.795) and more positive emotional reactions (higher PAC scores; rho = .764). Conclusions: The study provided some quantitative support for suggestions arising from qualitative research about how perceptions of continuity/discontinuity in the relationship may impact on the caregiving spouse's emotional well-being. Helping couples to maintain a sense of continuity and couplehood may assist their emotional adjustment to dementia

    Kinematically Cold Populations at Large Radii in the Draco and Ursa Minor Dwarf Spheroidals

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    We present projected velocity dispersion profiles for the Draco and Ursa Minor (UMi) dwarf spheroidal galaxies based on 207 and 162 discrete stellar velocities, respectively. Both profiles show a sharp decline in the velocity dispersion outside ~30 arcmin (Draco) and ~40 arcmin (UMi). New, deep photometry of Draco reveals a break in the light profile at ~25 arcmin. These data imply the existence of a kinematically cold population in the outer parts of both galaxies. Possible explanations of both the photometric and kinematic data in terms of both equilibrium and non-equilibrium models are discussed in detail. We conclude that these data challenge the picture of dSphs as simple, isolated stellar systems.Comment: 5 pages, accepted for publication in ApJ Letter
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