University of Hertforshire

Hatfield, United Kingdom

University of Hertforshire

Hatfield, United Kingdom
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Gullieuszik M.,Royal Observatory of Belgium | Groenewegen M.A.T.,Royal Observatory of Belgium | L. Cioni M.-R.,University of Hertforshire | L. Cioni M.-R.,Ludwig Maximilians University of Munich | And 8 more authors.
Astronomy and Astrophysics | Year: 2012

Context. Asymptotic giant branch (AGB) stars are major contributors to both the chemical enrichment of the interstellar medium and the integrated light of galaxies. Despite its importance, the AGB is one of the least understood phases of stellar evolution. The main difficulties associated with detailed modelling of the AGB are related to the mass-loss process and the 3rd dredge-up efficiency Aims. We provide direct measures of mass-loss rates and luminosities for a complete sample of AGB stars in the Large Magellanic Cloud, disentangling the C-and O-rich stellar populations. Methods. Dust radiative transfer models are presented for all 374 AGB stars candidates in one of the fields observed by the new VISTA survey of the Magellanic Clouds (VMC). Mass-loss rates, luminosities and a classification of C-and O-rich stars are derived by fitting the models to the spectral energy distribution (SED) obtained by combining VMC data with existing optical, near-, and mid-infrared photometry. Results. The classification technique is reliable at a level of-at worst-75% and significantly better for the reddest dusty stars. We classified none of the stars with a relevant mass-loss rate as O-rich, and we can exclude the presence of more than one dusty O-rich star at a ∼94% level. The bolometric luminosity function we obtained is fully consistent with most of the literature data on the LMC and with the prediction of theoretical models, with a peak of the C-star distribution at M bol ≈-4.8 mag and no stars brighter than the classical AGB tip, at M bol =-7.1 mag. Conclusions. This exploratory study shows that our method provides reliable mass-loss rates, luminosities and chemical classifications for all AGB stars. These results offer already important constraints to AGB evolutionary models. Most of our conclusions, especially for the rarer dust-enshrouded extreme AGB stars, are however strongly limited by the relatively small area covered by our study. Forthcoming VMC observations will easily remove this limitation. © 2012 ESO.

Crause L.A.,South African Astronomical Observatory | Sharples R.M.,Durham University | Bramall D.G.,Durham University | Schmoll J.,Durham University | And 10 more authors.
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2014

The Southern African Large Telescope (SALT) High Resolution Spectrograph (HRS) is a fibre-fed R4 échelle spectrograph employing a white pupil design with red and blue channels for wavelength coverage from 370-890nm. The instrument has four modes, each with object and sky fibres: Low (R∼15000), Medium (R∼40000) and High Resolution (R∼65000), as well as a High Stability mode for enhanced radial velocity precision at R∼65000. The High Stability mode contains a fibre double-scrambler and offers optional simultaneous Th-Ar arc injection, or the inclusion of an iodine cell in the beam. The LR mode has unsliced 500μm fibres and makes provision for nod-and-shuffle for improved background subtraction. The MR mode also uses 500μm fibres, while the HR and HS fibres are 350μm. The latter three modes employ modified Bowen-Walraven image-slicers to subdivide each fibre into three slices. All but the High Stability bench is sealed within a vacuum tank, which itself is enclosed in an interlocking Styrostone enclosure, to insulate the spectrograph against temperature and atmospheric pressure variations. The Fibre Instrument Feed (FIF) couples the four pairs of fibres to the telescope focal plane and allows the selection of the appropriate fibre pair for a given mode, and adjustment of the fibre separation to optimally position the sky fibre. The HRS employs a photomultiplier tube for an exposure meter and has a dedicated auto-guider attached to the FIF. We report here on the commissioning results and overall instrument performance since achieving first light on 28 September 2013. © 2014 SPIE.

Harries P.,Brunel University | Tomlinson C.,Imperial College London | Notley E.,Brunel University | Davies M.,Brunel University | Gilhooly K.,University of Hertforshire
Medical Decision Making | Year: 2012

Background. In the community mental health field, occupational therapy students lack the capacity to prioritize referrals effectively. Objective. The purpose of this study was to test the effectiveness of a clinical decision-training aid on referral prioritization capacity. Design. A double-blind, parallel-group, randomized controlled trial was conducted using a judgment analysis approach. Setting. Each participant used the World Wide Web to prioritize referral sets at baseline, immediate posttest, and 2-wk follow-up. The intervention group was provided with training after baseline testing; control group was purely given instructions to continue with the task. Participants. One hundred sixty-five students were randomly allocated to intervention (n = 87) or control (n = 81). Intervention. Written and graphical descriptions were given of an expert consensus standard explaining how referral information should be used to prioritize referrals. Measurements. Participants' prioritization ratings were correlated with the experts' ratings of the same referrals at each stage of testing, as well as to examine the effect on mean group scores, regression weights, and the lens model indices. Results. At baseline, no differences were found between control and intervention on rating capacity or demographic characteristics. Comparison of the difference in mean correlation baseline scores of the control and intervention group compared with immediate posttest showed a statistically significant result that was maintained at 2-wk follow-up. The effect size was classified as large. At immediate posttest and follow-up, the intervention group improved rating capacity, whereas the control group's capacity remained poor. The results of this study indicate that the decision-training aid has a positive effect on referral prioritization capacity. Conclusions. This freely available, Web-based decision-training aid will be a valuable adjunct to the education of these novice health professionals internationally.

Shen Q.,University of Hertforshire | Dautenhahn K.,University of Hertforshire | Saunders J.,University of Hertforshire | Kose H.,Technical University of Istanbul
IEEE Transactions on Autonomous Mental Development | Year: 2015

Previous research on social interaction among humans suggested that interpersonal motor coordination can help to establish social rapport. Our research addresses the question of whether, in a human-humanoid interaction experiment, the human's overall perception of a robot can be improved by realizing motor coordination behavior that allows the robot to adapt in real-time to a person's behavior. A synchrony detection method using information distance was adopted to realize the real-time human-robot motor coordination behavior, which guided the humanoid robot to coordinate its movements to a human by measuring the behavior synchrony between the robot and the human. The feedback of the participants indicated that most of the participants preferred to interact with the humanoid robot with the adaptive motor coordination capability. The results of this proof-of-concept study suggest that the motor coordination mechanism improved humans' overall perception of the humanoid robot. Together with our previous findings, namely that humans actively coordinate their behaviors to a humanoid robot's behaviors, this study further supports the hypothesis that bidirectional motor coordination could be a valid approach to facilitate adaptive human-humanoid interaction. © 2014 IEEE.

PubMed | University of Hertforshire
Type: Journal Article | Journal: British journal of nursing (Mark Allen Publishing) | Year: 2010

Lyn Karstadt reflects on the possible effects of future change in policy and practice, and how funding changes might affect students.

PubMed | University of Stockholm, University of Hertforshire and Oslo University College
Type: Journal Article | Journal: Journal of intellectual disabilities : JOID | Year: 2016

This article compares the welfare services for adults with an intellectual disability in three European countries: England, Norway and Sweden. The purpose of the comparison is to develop an understanding of the welfare state and institutional contexts of the country-specific policies and to develop a critical analysis through a comparative method based on selected secondary literature. Typological frameworks of European welfare states are applied as analytic frameworks to enable comparison between the countries. It is argued that there are international policy developments but these are shaped at a national level by different types of welfare states and histories. Through a comparison of similarities and differences, the article suggests that international policy ideas that impact on the lives of people with intellectual disabilities are mediated by different types of welfare states and institutions.

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