7,619 research outputs found
Searching for emission-line galaxies: The UCM survey
We are carrying out a long-term project with the main purposes of finding and analyzing low metallicity galaxies. A very small number of very low metallicity galaxies is known up to now. However these ojbects are particularly interesting since they are excellent candidates to 'young galaxies' in evolutionary sense as POX186 (Kunth, Maurogordato & Vigroux, 1988). Since the interstellar matter in these objects is only weakly contaminated by stellar evolution, their study could provide valuable information about the primordial helium abundance and therefore it could place constraints on the different Big-Bang models. The instrumental set up of our survey is an objective-prism used with the Schmidt telescope at Calar Alto Observatory. By using hypersensitized IIIaF emulsion and RG630 filter low resolution spectra in the H alpha region of objects in a wide field is obtained (Rego et al. 1989, Zamorano et al. 1990). Surveys carried out in the past two decades at optical blue wavelengths have also produced large samples of emission-line galaxies (ELGs), for example MacAlpine & Willians 1981 and reference therein, Wasilewski 1983, Salzer and MacAlpine 1988, or Smith et al. 1976. Relying primarily on objective-prism plates taken in the blue, these surveys have found over 3000 blue/emission-line galaxies so far. A significant number of star-forming galaxies are missed by optical surveys in the blue because of their low-excitation spectra (MacAlpine and Willians 1981, Markarian et al. 1981 and references therein) or their low metallicity (Kunth and Sargent, 1986)
Health inequalities and development plans in Iran: An analysis of the past three decades (1984–2010)
Introduction: Reducing inequalities in health care is one of the main challenges in all countries. In Iran as in other oil-exporting upper middle income countries, we expected to witness fewer inequalities especially in the health sector with the increase in governmental revenues.
Methods: This study presents an inequalities assessment of health care expenditures in Iran. We used data from the Household Income and Expenditure Survey (HIES) in Iran from 1984–2010. The analysis included 308,735 urban and 342,532 rural households.
Results: The results suggest heightened inequality in health care expenditures in Iran over the past three decades, including an increase in the gap between urban and rural areas. Furthermore, inflation has affected the poor more than the rich. The Kakwani progressivity index in all years is positive, averaging 0.436 in rural and 0.470 in urban areas during the time period of analysis. Compared to inequality in income distribution over the last 30 years, health expenditures continuously show more inequality and progressivity over the same period of time.
Conclusions: According to the result of our study, during this period Iran introduced four National Development Plans (NDPs); however, the NDPs failed to provide sustainable strategies for reducing inequalities in health care expenditures. Policies that protect vulnerable groups should be prioritized
Work and entropy production in generalised Gibbs ensembles
Recent years have seen an enormously revived interest in the study of
thermodynamic notions in the quantum regime. This applies both to the study of
notions of work extraction in thermal machines in the quantum regime, as well
as to questions of equilibration and thermalisation of interacting quantum
many-body systems as such. In this work we bring together these two lines of
research by studying work extraction in a closed system that undergoes a
sequence of quenches and equilibration steps concomitant with free evolutions.
In this way, we incorporate an important insight from the study of the dynamics
of quantum many body systems: the evolution of closed systems is expected to be
well described, for relevant observables and most times, by a suitable
equilibrium state. We will consider three kinds of equilibration, namely to (i)
the time averaged state, (ii) the Gibbs ensemble and (iii) the generalised
Gibbs ensemble (GGE), reflecting further constants of motion in integrable
models. For each effective description, we investigate notions of entropy
production, the validity of the minimal work principle and properties of
optimal work extraction protocols. While we keep the discussion general, much
room is dedicated to the discussion of paradigmatic non-interacting fermionic
quantum many-body systems, for which we identify significant differences with
respect to the role of the minimal work principle. Our work not only has
implications for experiments with cold atoms, but also can be viewed as
suggesting a mindset for quantum thermodynamics where the role of the external
heat baths is instead played by the system itself, with its internal degrees of
freedom bringing coarse-grained observables to equilibrium.Comment: 22 pages, 4 figures, improvements in presentatio
Strong coupling corrections in quantum thermodynamics
Quantum systems strongly coupled to many-body systems equilibrate to the
reduced state of a global thermal state, deviating from the local thermal state
of the system as it occurs in the weak-coupling limit. Taking this insight as a
starting point, we study the thermodynamics of systems strongly coupled to
thermal baths. First, we provide strong-coupling corrections to the second law
applicable to general systems in three of its different readings: As a
statement of maximal extractable work, on heat dissipation, and bound to the
Carnot efficiency. These corrections become relevant for small quantum systems
and always vanish in first order in the interaction strength. We then move to
the question of power of heat engines, obtaining a bound on the power
enhancement due to strong coupling. Our results are exemplified on the
paradigmatic situation of non-Markovian quantum Brownian motion.Comment: 20 pages, 3 figures, version two is substantially revised and
contains new result
Carers\u27 preferences for the delivery of therapy services for people with disability in rural Australia: Evidence from a discrete choice experiment
Background: The implementation of the Australian National Disability Insurance Scheme (NDIS) is expected to generate a responsive, person-centred system that will empower people with disability to choose the services and support they receive. However little attention has been paid to examine how users of the NDIS will choose and spend their individual budgets. This study aimed to determine quantitatively the relative importance that carers of people with a disability living in rural Australia place on different therapy service delivery characteristics.
Methods: A stated preference discrete choice experiment (DCE) was incorporated into a survey of carers of people with disability living in rural Australia. Carers chose between therapy delivery services differing in attributes such as travel time to receive therapy, sector providing the service (i.e. Government, not-for-profit, private), out-of-pocket costs, person who delivers the therapy (therapist or other staff) and waiting time.
Results: A total of 133 carers completed the DCE. The majority of respondents cared for a child with a disability (84%), the average age of the person they cared for was 17 years (SD 14.25). Participants expressed strong preferences for a short waiting time (0-3 months) to receive therapy services; services delivered by a therapist, no out of pocket cost and travelling up to 4 hours to receive a therapy session (p
Conclusion: Carers of people with a disability in rural Australia exhibited strongest preferences for short waiting times (0-3 months). Therapy services that are delivered by therapy assistants or support workers will require careful introduction to achieve uptake and acceptability
Pseudospectral versus finite-differences schemes in the numerical integration of stochastic models of surface growth
We present a comparison between finite differences schemes and a
pseudospectral method applied to the numerical integration of stochastic
partial differential equations that model surface growth. We have studied, in
1+1 dimensions, the Kardar, Parisi and Zhang model (KPZ) and the Lai, Das Sarma
and Villain model (LDV). The pseudospectral method appears to be the most
stable for a given time step for both models. This means that the time up to
which we can follow the temporal evolution of a given system is larger for the
pseudospectral method. Moreover, for the KPZ model, a pseudospectral scheme
gives results closer to the predictions of the continuum model than those
obtained through finite difference methods. On the other hand, some numerical
instabilities appearing with finite difference methods for the LDV model are
absent when a pseudospectral integration is performed. These numerical
instabilities give rise to an approximate multiscaling observed in the
numerical simulations. With the pseudospectral approach no multiscaling is seen
in agreement with the continuum model.Comment: 13 single column pages, RevTeX, 6 eps fig
Factors affecting retention of allied health professionals working with people with disability in rural New South Wales, Australia: discrete choice experiment questionnaire development
Objective: This paper describes the development of a discrete choice experiment (DCE) questionnaire to identify the factors (attributes) that allied health professionals (AHPs) working with people with disability identify as important to encouraging them to remain practising in rural areas.
Methods: Focus groups and semi-structured interviews were conducted with 97 purposively selected service providers working with people with disability in rural New South Wales, Australia. Focus groups and interviews were digitally recorded, transcribed, and analysed using a modified grounded theory approach involving thematic analysis and constant comparison.
Results: Six attributes that may influence AHPs working with people with disability in rural areas to continue to do so were inductively identified: travel arrangements, work flexibility, professional support, professional development, remuneration, and autonomy of practice. The qualitative research information was combined with a policy review to define these retention factors and ensure that they are amenable to policy changes.
Conclusion: The use of various qualitative research methods allowed the development of a policy-relevant DCE questionnaire that was grounded in the experience of the target population (AHPs)
Level and length of cyclic solar activity during the Maunder minimum as deduced from the active day statistics
The Maunder minimum (MM) of greatly reduced solar activity took place in
1645-1715, but the exact level of sunspot activity is uncertain as based, to a
large extent, on historical generic statements of the absence of spots on the
Sun. Here we aim, using a conservative approach, to assess the level and length
of solar cycle during the Maunder minimum, on the basis of direct historical
records by astronomers of that time. A database of the active and inactive days
(days with and without recorded sunspots on the solar disc respectively) is
constructed for three models of different levels of conservatism (loose ML,
optimum MO and strict MS models) regarding generic no-spot records. We have
used the active day fraction to estimate the group sunspot number during the
MM. A clear cyclic variability is found throughout the MM with peaks at around
1655--1657, 1675, 1684 and 1705, and possibly 1666, with the active day
fraction not exceeding 0.2, 0.3 or 0.4 during the core MM, for the three
models. Estimated sunspot numbers are found very low in accordance with a grand
minimum of solar activity.
We have found, for the core MM (1650-1700), that: (1) A large fraction of
no-spot records, corresponding to the solar meridian observations, may be
unreliable in the conventional database. (2) The active day fraction remained
low (below 0.3-0.4) throughout the MM, indicating the low level of sunspot
activity. (3) The solar cycle appears clearly during the core MM. (4) The
length of the solar cycle during the core MM appears years, but there
is an uncertainty in that. (5) The magnitude of the sunspot cycle during MM is
assessed to be below 5-10 in sunspot numbers;
A hypothesis of the high solar cycles during the MM is not confirmed.Comment: Accepted to Astron. Astrophy
Friedel oscillations induced surface magnetic anisotropy
We present detailed numerical studies of the magnetic anisotropy energy of a
magnetic impurity near the surface of metallic hosts (Au and Cu), that we
describe in terms of a realistic tight-binding surface Green's function
technique. We study the case when spin-orbit coupling originates from the
d-band of the host material and we also investigate the case of a strong local
spin-orbit coupling on the impurity itself. The splitting of the impurity's
spin-states is calculated to leading order in the exchange interaction between
the impurity and the host atoms using a diagrammatic Green's function
technique. The magnetic anisotropy constant is an oscillating function of the
separation d from the surface: it asymptotically decays as 1/d2 and its
oscillation period is determined by the extremal vectors of the host's Fermi
Surface. Our results clearly show that the host-induced magnetic anisotropy
energy is by several orders of magnitude smaller than the anisotropy induced by
the local mechanism, which provides sufficiently large anisotropy values to
explain the size dependence of the Kondo resistance observed experimentally.Comment: 11 pages, 7 figures, submitted to PR
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