66 research outputs found
Beyond the Lognormal Approximation: a General Simulation Scheme
We present a public code to generate random fields with an arbitrary
probability distribution function (PDF) and an arbitrary correlation function.
The algorithm is cosmology-independent, applicable to any stationary stochastic
process over a three dimensional grid. We implement it in the case of the
matter density field, showing its benefits over the lognormal approximation,
which is often used in cosmology for generation of mock catalogues. We find
that the covariance of the power spectrum from the new fast realizations is
more accurate than that from a lognormal model. As a proof of concept, we also
apply the new simulation scheme to the divergence of the Lagrangian
displacement field. We find that information from the correlation function and
the PDF of the displacement-divergence provides modest improvement over other
standard analytical techniques to describe the particle field in the
simulation. This suggests that further progress in this direction should come
from multi-scale or non-local properties of the initial matter distribution.Comment: 14 pages, 17 figures. The code for ITAM is available at
https://github.com/tos-1/ITAM . The code for MUSCLE is at
https://github.com/tos-1/MUSCLE . Minor modifications to match the accepted
MNRAS versio
MUSCLE-UPS: Improved Approximations of the Matter Field with the Extended Press-Schechter Formalism and Lagrangian Perturbation Theory
Lagrangian algorithms to simulate the evolution of cold dark matter (CDM) are
invaluable tools to generate large suites of mock halo catalogues. In this
paper, we first show that the main limitation of current semi-analytical
schemes to simulate the displacement of CDM is their inability to model the
evolution of overdensities in the initial density field, a limit that can be
circumvented by detecting halo particles in the initial conditions. We thus
propose `MUltiscale Spherical Collapse Lagrangian Evolution Using
Press-Schechter' (muscle-ups), a new scheme that reproduces the results from
Lagrangian perturbation theory on large scales, while improving the modelling
of overdensities on small scales. In muscle-ups, we adapt the extended Press
and Schechter (EPS) formalism to Lagrangian algorithms of the displacement
field. For regions exceeding a collapse threshold in the density smoothed at a
radius , we consider all particles within a radius collapsed. Exploiting
a multi-scale smoothing of the initial density, we build a halo catalogue on
the fly by optimizing the selection of halo candidates. This allows us to
generate a density field with a halo mass function that matches one measured in
-body simulations. We further explicitly gather particles in each halo
together in a profile, providing a numerical, Lagrangian-based implementation
of the halo model. Compared to previous semi-analytical Lagrangian methods, we
find that muscle-ups improves the recovery of the statistics of the density
field at the level of the probability density function (PDF), the power
spectrum, and the cross correlation with the -body result.Comment: 19 pages, 11 figures. Modest changes to the text to match the
referee's comments, results unchanged. Comments are welcom
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Compassionate pedagogy: the ethics of care in early childhood professionalism
This paper builds upon an earlier attempt (Taggart, 2011) to articulate a rationale for professional training in early childhood education and care (ECEC) which is ethical as opposed to one which is purely instrumental or rooted in a patriarchal notion of women’s supposed unique suitability. The argument proposes that a feminist approach to ethics, as both socially critical and psychologically affective or flexible, has a particular relevance to professional identity in ECEC. In particular, compassion, as a concept which has both sociological and psychological connotations, foregrounds the ethical dimension of the work whilst overcoming false dichotomies between discourses of ‘children’s rights’ and ‘care’. The implications for the training and professional identity of practitioners are discussed
Ripples in a pond: Do social work students need to learn about terrorism?
In the face of heightened awareness of terrorism, however it is defined, the challenges for social work are legion. Social work roles may include working with the military to ensure the well-being of service-men and women and their families when bereaved or injured, as well as being prepared to support the public within the emergency context of an overt act of terrorism. This paper reviews some of the literature concerning how social work responds to confl ict and terrorism before reporting a smallscale qualitative study examining the views of social work students, on a qualifying programme in the UK, of terrorism and the need for knowledge and understanding as part of their education
Social and occupational factors associated with psychological distress and disorder among disaster responders: a systematic review
BACKGROUND: When disasters occur, there are many different occupational groups involved in rescue, recovery and support efforts. This study aimed to conduct a systematic literature review to identify social and occupational factors affecting the psychological impact of disasters on responders. METHODS: Four electronic literature databases (MEDLINE®, Embase, PsycINFO® and Web of Science) were searched and hand searches of reference lists were carried out. Papers were screened against specific inclusion criteria (e.g. published in peer-reviewed journal in English; included a quantitative measure of wellbeing; participants were disaster responders). Data was extracted from relevant papers and thematic analysis was used to develop a list of key factors affecting the wellbeing of disaster responders. RESULTS: Eighteen thousand five papers were found and 111 included in the review. The psychological impact of disasters on responders appeared associated with pre-disaster factors (occupational factors; specialised training and preparedness; life events and health), during-disaster factors (exposure; duration on site and arrival time; emotional involvement; peri-traumatic distress/dissociation; role-related stressors; perceptions of safety, threat and risk; harm to self or close others; social support; professional support) and post-disaster factors (professional support; impact on life; life events; media; coping strategies). CONCLUSIONS: There are steps that can be taken at all stages of a disaster (before, during and after) which may minimise risks to responders and enhance resilience. Preparedness (for the demands of the role and the potential psychological impact) and support (particularly from the organisation) are essential. The findings of this review could potentially be used to develop training workshops for professionals involved in disaster response. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s40359-016-0120-9) contains supplementary material, which is available to authorized users
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