22,607 research outputs found
M2M modelling of the Galactic disc via PRIMAL: Fitting to Gaia Error Added Data
We have adapted our made-to-measure (M2M) algorithm PRIMAL to use mock Milky
Way like data constructed from an N-body barred galaxy with a boxy bulge in a
known dark matter potential. We use M0 giant stars as tracers, with the
expected error of the ESA space astrometry mission Gaia. We demonstrate the
process of constructing mock Gaia data from an N-body model, including the
conversion of a galactocentric Cartesian coordinate N-body model into
equatorial coordinates and how to add error to it for a single stellar type. We
then describe the modifications made to PRIMAL to work with observational
error. This paper demonstrates that PRIMAL can recover the radial profiles of
the surface density, radial velocity dispersion, vertical velocity dispersion
and mean rotational velocity of the target disc, along with the pattern speed
of the bar, to a reasonable degree of accuracy despite the lack of accurate
target data. We also construct mock data which take into account dust
extinction and show that PRIMAL recovers the structure and kinematics of the
disc reasonably well. In other words, the expected accuracy of the Gaia data is
good enough for PRIMAL to recover these global properties of the disc, at least
in a simplified condition, as used in this paper.Comment: 16 pages, 10 figures, submitted to MNRAS 17th Dec 2013, accepted 30th
June 201
Managing multiple morbidity in mid-life: a qualitative study of attitudes to drug use
OBJECTIVE: To examine attitudes towards drug use among middle aged respondents with high levels of chronic morbidity. DESIGN: Qualitative study with detailed interviews. SETTING: West of Scotland. PARTICIPANTS: 23 men and women aged about 50 years with four or more chronic illnesses. MAIN OUTCOME MEASURE: Participants' feelings about long term use of drugs to manage chronic multiple morbidity. RESULTS: Drugs occupied a central place in the way people managed their comorbidities. Respondents expressed an aversion to taking drugs, despite acknowledging that they depended on drugs to live as "normal" a life as possible. Respondents expressed ambivalence to their drugs in various ways. Firstly, they adopted both regular and more flexible regimens and might adhere to a regular regimen in treating one condition (such as hypertension) while adopting a flexible regimen in relation to others, in response to their experience of symptoms or varying demands of their daily life. Secondly, they expressed reluctance to take drugs, but an inability to be free of them. Thirdly, drugs both facilitated performance of social roles and served as evidence of an inability to perform such roles. CONCLUSIONS: Insight into the considerable tension experienced by people managing complex drug regimens to manage multiple chronic illness may help medical carers to support self care practices among patients and to optimise concordance in their use of prescribed drugs
Open Access Policy: Numbers, Analysis, Effectiveness
The PASTEUR4OA project analyses what makes an Open Access (OA) policy
effective. The total number of institutional or funder OA policies worldwide is
now 663 (March 2015), over half of them mandatory. ROARMAP, the policy
registry, has been rebuilt to record more policy detail and provide more
extensive search functionality. Deposit rates were measured for articles in
institutions' repositories and compared to the total number of WoS-indexed
articles published from those institutions. Average deposit rate was over four
times as high for institutions with a mandatory policy. Six positive
correlations were found between deposit rates and (1) Must-Deposit; (2)
Cannot-Waive-Deposit; (3) Deposit-Linked-to-Research-Evaluation; (4)
Cannot-Waive-Rights-Retention; (5) Must-Make-Deposit-OA (after allowable
embargo) and (6) Can-Waive-OA. For deposit latency, there is a positive
correlation between earlier deposit and (7) Must-Deposit-Immediately as well as
with (4) Cannot-Waive-Rights-Retention and with mandate age. There are not yet
enough OA policies to test whether still further policy conditions would
contribute to mandate effectiveness but the present findings already suggest
that it would be useful for current and future OA policies to adopt the seven
positive conditions so as to accelerate and maximise the growth of OA.Comment: 49 pages, 21 figures, 15 tables. Pasteur4OA Work Package 3 report:
Open Access policies 201
A Semantic Hierarchy for Erasure Policies
We consider the problem of logical data erasure, contrasting with physical
erasure in the same way that end-to-end information flow control contrasts with
access control. We present a semantic hierarchy for erasure policies, using a
possibilistic knowledge-based semantics to define policy satisfaction such that
there is an intuitively clear upper bound on what information an erasure policy
permits to be retained. Our hierarchy allows a rich class of erasure policies
to be expressed, taking account of the power of the attacker, how much
information may be retained, and under what conditions it may be retained.
While our main aim is to specify erasure policies, the semantic framework
allows quite general information-flow policies to be formulated for a variety
of semantic notions of secrecy.Comment: 18 pages, ICISS 201
Using Simple Neural Networks to Correct Errors in Optical Data Transmission.
We have demonstrated the applicability of
neural-network-based systems to the problem
of reducing the effects of signal distortion,
and shown that such a system has the potential
to reduce the bit-error-rate in the digitized
version of the analogue electrical signal
derived from an optical data stream by a
substantial margin over existing techniques
Stellar Motion around Spiral Arms: Gaia Mock Data
We compare the stellar motion around a spiral arm created in two different
scenarios, transient/co-rotating spiral arms and density-wave-like spiral arms.
We generate Gaia mock data from snapshots of the simulations following these
two scenarios using our stellar population code, SNAPDRAGONS, which takes into
account dust extinction and the expected Gaia errors. We compare the observed
rotation velocity around a spiral arm similar in position to the Perseus arm,
and find that there is a clear difference in the velocity features around the
spiral arm between the co-rotating spiral arm and the density-wave-like spiral
arm. Our result demonstrates that the volume and accuracy of the Gaia data are
sufficient to clearly distinguish these two scenarios of the spiral arms.Comment: 5 pages, 1 figure, to appear in the proceedings of "The Milky Way
Unravelled by Gaia: GREAT Science from the Gaia Data Releases", Barcelona,
1-5 December 2014, eds. N. Walton, F. Figueras, C. Soubira
Effect of detraining on bone and muscle tissue in subjects with chronic spinal cord injury after a period of electrically-stimulated cycling: a small cohort study
Objective: To investigate adaptive changes in bone and muscle parameters in the paralysed limbs after de-training or reduced functional electrical stimulation (FES) induced cycling following high-volume FES-cycling in chronic spinal cord injury (SCI).
Subjects: Five subjects with motor-sensory complete SCI (age 38.6 years, lesion duration 11.4 years) were included. Four subjects stopped FES-cycling completely after the training phase whereas one continued reduced FES-cycling (2-3 times/week, for 30min).
Methods: Bone and muscle parameters were assessed in the legs using peripheral quantitative computed tomography at six and twelve months after cessation of high-volume FES-cycling.
Results: Gains achieved in the distal femur by high-volume FES-cycling were partly maintained at one year of detraining: 73.0% in trabecular bone mineral density (BMD), 63.8% in total BMD, 59.4% in bone mineral content and 22.1% in muscle cross-sectional area (CSAmuscle) in the thigh. The subject who continued reduced FES-cycling maintained 96.2% and 95.0% of the previous gain in total and trabecu-lar BMD, and 98.5% in CSAmuscle.
Conclusion: Bone and muscle benefits achieved by one year of high-volume FES-cycling are partly preserved after 12 months of detraining whereas reduced cycling maintains bone and muscle mass gained. This suggests that high-volume FES-cycling has clinical relevance for at least 1y after detraining
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