Simulations of shell galaxies with GADGET-2: Multi-generation shell systems

As the missing complement to existing studies of shell galaxies, we carried out a set of self-consistent N-body simulations of a minor merger forming a stellar shell system within a giant elliptical galaxy. We discuss the effect of a phenomenon possibly associated with the galaxy merger simulations --- a presence of multiple generations of shells.Comment: 2 pages, 1 figure, to appear in the Proceedings of JENAM 2010, Symposium 2: "Environment and the formation of galaxies: 30 years later

Quantum nature of Gaussian discord : experimental evidence and role of system-environment correlations

L.M. acknowledges Project No. P205/12/0694 of Czech Science Foundation (GACR). N.K. is grateful for the support provided by the A. von Humboldt Foundation. N.Q. and N.K. acknowledge the support from the Scottish Universities Physics Alliance (SUPA) and the Engineering and Physical Sciences Research Council (EPSRC). The project was supported within the framework of the BMBF grant “QuORep” and in the framework of the International Max Planck Partnership (IMPP) with Scottish Universities.We provide experimental evidence of quantum features in bipartite states classified as entirely classical according to a conventional criterion based on the Glauber P function but possessing nonzero Gaussian quantum discord. Their quantum nature is experimentally revealed by acting locally on one part of the discordant state. We experimentally verify and investigate the effect of discord increase under the action of local loss and link it to the entanglement with the environment. Adding an environmental system purifying the state, we unveil the flow of quantum correlations within a global pure system using the Koashi-Winter inequality. For a discordant state generated by splitting a state in which the initial squeezing is destroyed by random displacements, we demonstrate the recovery of entanglement highlighting the role of system-environment correlations.Publisher PDFPeer reviewe

Zero-bias Anomaly of Tunneling into the Edge of a 2D Electron System

We investigate the electron tunneling into the edge of a clean weakly interacting two-dimensional electron gas. It is shown that the corresponding differential conductance $G(V)$ has a cusp at zero bias, and is characterized by a universal slope $|dG/dV|$ at $V=0$. This singularity originates from the electron scattering on the Friedel oscillation caused by the boundary of the system.Comment: 10 pages, uuencoded compressed Postscript file, to appear in Phys. Rev. B (Rapid Communications

Axiomatic approach to radiation reaction of scalar point particles in curved spacetime

Several different methods have recently been proposed for calculating the motion of a point particle coupled to a linearized gravitational field on a curved background. These proposals are motivated by the hope that the point particle system will accurately model certain astrophysical systems which are promising candidates for observation by the new generation of gravitational wave detectors. Because of its mathematical simplicity, the analogous system consisting of a point particle coupled to a scalar field provides a useful context in which to investigate these proposed methods. In this paper, we generalize the axiomatic approach of Quinn and Wald in order to produce a general expression for the self force on a point particle coupled to a scalar field following an arbitrary trajectory on a curved background. Our equation includes the leading order effects of the particle's own fields, commonly referred to as ``self force'' or ``radiation reaction'' effects. We then explore the equations of motion which follow from this expression in the absence of non-scalar forces.Comment: 17 pages, 1 figur

Pre-school experience and Key Stage 2 performance in English and Mathematics

This report considers children\u27s educational attainment in English and mathematics at the end of primary school (age 11). Children\u27s educational attainment in English and mathematics was derived from their national Key Stage 2 assessments. The analyses have considered the child\u27s level of Key Stage 2 attainment in terms of the effects of child, family, home environment and preschool experience variables as well as the child\u27s ability at the start of primary school

Applying Bayesian belief networks (BBNs) with stakeholders to explore and codesign options for water resource interventions

Bayesian Belief networks (BBNs) are a useful tool to account for uncertainty and can be used to incorporate stakeholder understandings of how a system works. In this study, BBNs were applied to elicit and discuss local stakeholders’ concerns in conflicts over water resource planning in two cases in southern Thailand. One concerned the construction of a dam proposed by a top-down project. The other concerned a bottom-up participatory process at the catchment scale to assess the need for water resources interventions and explore perceptions on alternative design options. In the top-down project, the responses of participants during the elaboration of the BBN showed that potentially affected stakeholders were particularly concerned about limited consultation and lack of shared benefits, which led them to oppose the dam project. In the bottom-up project, local stakeholders expected and agreed with the benefits of a dam, proposing to locate the dam upstream of community land. The BBN method did not facilitate dialogue in the top-down dam-building project because no alternative design options could be discussed and potentially affected stakeholders did not want to discuss compensation because of mistrust and differences in valuation of effects. In the bottom-up project, the BBN method did facilitate dialogue on alternative intervention options and their effects. The replicable BBN framework can support policy-makers to better understand water conflict situations in different stages of planning. Its application supports exploring a wider repertoire of options, enlarging the scope for more inclusive and sustainable solutions to water resource conflicts

Self-force of a scalar field for circular orbits about a Schwarzschild black hole

The foundations are laid for the numerical computation of the actual worldline for a particle orbiting a black hole and emitting gravitational waves. The essential practicalities of this computation are here illustrated for a scalar particle of infinitesimal size and small but finite scalar charge. This particle deviates from a geodesic because it interacts with its own retarded field \psi^\ret. A recently introduced Green's function G^\SS precisely determines the singular part, \psi^\SS, of the retarded field. This part exerts no force on the particle. The remainder of the field \psi^\R = \psi^\ret - \psi^\SS is a vacuum solution of the field equation and is entirely responsible for the self-force. A particular, locally inertial coordinate system is used to determine an expansion of \psi^\SS in the vicinity of the particle. For a particle in a circular orbit in the Schwarzschild geometry, the mode-sum decomposition of the difference between \psi^\ret and the dominant terms in the expansion of \psi^\SS provide a mode-sum decomposition of an approximation for $\psi^\R$ from which the self-force is obtained. When more terms are included in the expansion, the approximation for $\psi^\R$ is increasingly differentiable, and the mode-sum for the self-force converges more rapidly.Comment: RevTex, 31 pages, 1 figure, modified abstract, more details of numerical method

Social Support and Attitudes to Aging in Later Life

Negative attitudes to aging are a risk factor for poor health and well-being. The current study sought to examine satisfaction with social support as a potentially modifiable factor that might facilitate the development of more positive attitudes to aging. A convenience sample of 501 older respondents (Mage = 72.06) reported on frequency of social support and their satisfaction with it, as well as completing a rating of attachment (model of the self and others), a measure of attitudes to aging, and a number of background measures. Results indicated that better subjective health, younger age, and greater satisfaction with social support were all significant predictors of more positive attitudes to aging, while frequency of social support was not. Model of the self accounted for some variation in satisfaction with social support. Interventions to increase satisfaction with social support in later life, recognizing individual differences and attachment styles, may improve attitudes to aging, and further support health and well-being.Data collection for this study was supported by the ESRC grant (RES-000-22-4117) awarded to S.M. Nelis (PI), L. Clare and C.J. Whitaker. We also acknowledge the support of the ESRC and NIHR through grant ES/L001853/1 ‘Improving the experience of dementia and enhancing active life: living well with dementia’ (Investigators: L. Clare, I.R. Jones, C.Victor, J.V. Hindle, R.W.Jones, M.Knapp, M.Kopelman, A.Martyr, F.Matthews, R.G.Morris, S.M.Nelis, J.Pickett, C.Quinn, J.Rusted, N.Savitch, J.Thom)