Rip/singularity free cosmology models with bulk viscosity

In this paper we present two concrete models of non-perfect fluid with bulk viscosity to interpret the observed cosmic accelerating expansion phenomena, avoiding the introduction of exotic dark energy. The first model we inspect has a viscosity of the form ${\zeta} = {\zeta}_0 + ({\zeta}_1-{\zeta}_2q)H$ by taking into account of the decelerating parameter q, and the other model is of the form ${\zeta} = {\zeta}_0 + {\zeta}_1H + {\zeta}_2H^2$. We give out the exact solutions of such models and further constrain them with the latest Union2 data as well as the currently observed Hubble-parameter dataset (OHD), then we discuss the fate of universe evolution in these models, which confronts neither future singularity nor little/pseudo rip. From the resulting curves by best fittings we find a much more flexible evolution processing due to the presence of viscosity while being consistent with the observational data in the region of data fitting. With the bulk viscosity considered, a more realistic universe scenario is characterized comparable with the {\Lambda}CDM model but without introducing the mysterious dark energy.Comment: 9 pages, 6 figures, submitted to EPJ-

Consistent Truncation to Three Dimensional (Super-)gravity

For a general three dimensional theory of (super-)gravity coupled to arbitrary matter fields with arbitrary set of higher derivative terms in the effective action, we give an algorithm for consistently truncating the theory to a theory of pure (super-)gravity with the gravitational sector containing only Einstein-Hilbert, cosmological constant and Chern-Simons terms. We also outline the procedure for finding the parameters of the truncated theory. As an example we consider dimensional reduction on S^2 of the 5-dimensional minimal supergravity with curvature squared terms and obtain the truncated theory without any curvature squared terms. This truncated theory reproduces correctly the exact central charge of the boundary CFT.Comment: LaTeX file, 22 page

Components of good end of life care within the paediatric intensive care setting – an online survey

BACKGROUND This study was undertaken to better understand the components of good end of life for children who are being cared for within the PICU. Cure rates from serious childhood illness are gradually improving every year. Despite this, there are still a small but significant number of children who will die within a Paediatric Intensive Care Unit. OBJECTIVES 1. The primary objective was to determine what the key aspects of End-of-Life-Care/palliative care in PICU as perceived by Health Professionals (including General Paediatricians) 2. This project will result in a schema of components of care which can be used by health professionals within in the intensive care setting to assist with excellent end of life care. METHOD An online survey of health professionals was used to rank various components of palliative care within the PICU context. Survey participants could also suggest other components of care that had not already been thought of within the survey. RESULTS There were 108 respondents who took the survey. The survey group were multidisciplinary (medical 32.4%; nursing 44.44% and allied health 23.15 %). There were also a variety of specialties represented in the survey (PICU 56.5 %; Paediatric Palliative Care 17.4%; General Paediatrics 13.9% and Other 12.2 %). The top 5 components of care ranked by the group included were identified by the interest groups after being ranked according to their importance. These included 1. Discussion of a Management Plan 2. Sensitive, compassionate use of language 3. Discussion of End of Life care 4. Discussion of anticipated changes in the patient's condition 5. Discussion of the caregiver's understanding of the illness. CONCLUSION It is hoped that the schema for good end of life care represents a consensus from a large and diverse group of health professionals. This schema should assist in the day to day care of patients. Further, it should also be of benefit in education, research and quality activities

Phase Mixing of Nonlinear Plasma Oscillations in an Arbitrary Mass Ratio Cold Plasma

Nonlinear plasma oscillations in an arbitrary mass ratio cold plasma have been studied using 1-D particle-in-cell simulation. In contrast to earlier work for infinitely massive ion plasmas it has been found that the oscillations phase mix away at any amplitude and that the rate at which phase mixing occurs, depends on the mass ratio ($\Delta = m_{-}/m_{+}$) and the amplitude. A perturbation theoretic calculation carried upto third order predicts that the normalized phase mixing time $\omega_{p-} t_{mix}$ depends on the amplitude $A$ and the mass ratio $\Delta$ as $\sim [(A^{2}/24)(\Delta/\sqrt{1 + \Delta})]^{-1/3}$. We have confirmed this scaling in our simulations and conclude that stable non-linear oscillations which never phase mix, exist only for the ideal case with $\Delta = 0.0$ and $A < 0.5$. These cold plasma results may have direct relevance to recent experiments on superintense laser beam plasma interactions with applications to particle acceleration, fast ignitor concept etc.Comment: pp 10 and two figures in PS forma