Two physical characteristics of numerical apparent horizons

This article translates some recent results on quasilocal horizons into the language of $(3+1)$ general relativity so as to make them more useful to numerical relativists. In particular quantities are described which characterize how quickly an apparent horizon is evolving and how close it is to either equilibrium or extremality.Comment: 6 pages, 2 figures, conference proceedings loosely based on talk given at Theory Canada III (Edmonton, Alberta, 2007). V2: Minor changes in response to referees comments to improve clarity and fix typos. One reference adde

Molecular clouds in the centers of galaxies: Constraints from HCN and CO-13 line emission

We have searched for HCN J=1-0 line emission in the centers of 12 galaxies and have detected it in 10 of them. We have obtained complementary data on J=1-0 and 2-1 transitions of CO-12 and CO-13 in these systems. The ratio of integrated intensities, I(CO 1-0)/I(HCN 1-0) = 25 +/- 11 for this sample. We find that HCN emission of this strength can be produced under conditions of subthermal excitation. In combination with the line ratios in CO and CO-13, HCN puts constraints on the mean conditions of molecular clouds and on the mix of cloud types within the projected beam

Horizon energy and angular momentum from a Hamiltonian perspective

Classical black holes and event horizons are highly non-local objects, defined in terms of the causal past of future null infinity. Alternative, (quasi)local definitions are often used in mathematical, quantum, and numerical relativity. These include apparent, trapping, isolated, and dynamical horizons, all of which are closely associated to two-surfaces of zero outward null expansion. In this paper we show that three-surfaces which can be foliated with such two-surfaces are suitable boundaries in both a quasilocal action and a phase space formulation of general relativity. The resulting formalism provides expressions for the quasilocal energy and angular momentum associated with the horizon. The values of the energy and angular momentum are in agreement with those derived from the isolated and dynamical horizon frameworks.Comment: 39 pages, 3 figures, Final Version : content essentially unchanged but many small improvements made in response to referees, a few references adde

Energy-weighted density matrix embedding of open correlated chemical fragments

We present a multi-scale approach to efficiently embed an ab initio correlated chemical fragment described by its energy-weighted density matrices, and entangled with a wider mean-field many-electron system. This approach, first presented in Phys. Rev. B, 98, 235132 (2018), is here extended to account for realistic long-range interactions and broken symmetry states. The scheme allows for a systematically improvable description in the range of correlated fluctuations out of the fragment into the system, via a self-consistent optimization of a coupled auxiliary mean-field system. It is discussed that the method has rigorous limits equivalent to existing quantum embedding approaches of both dynamical mean-field theory, as well as density matrix embedding theory, to which this method is compared, and the importance of these correlated fluctuations is demonstrated. We derive a self-consistent local energy functional within the scheme, and demonstrate the approach for Hydrogen rings, where quantitative accuracy is achieved despite only a single atom being explicitly treated.Comment: 14 pages, 8 figure

Fundamental properties and applications of quasi-local black hole horizons

The traditional description of black holes in terms of event horizons is inadequate for many physical applications, especially when studying black holes in non-stationary spacetimes. In these cases, it is often more useful to use the quasi-local notions of trapped and marginally trapped surfaces, which lead naturally to the framework of trapping, isolated, and dynamical horizons. This framework allows us to analyze diverse facets of black holes in a unified manner and to significantly generalize several results in black hole physics. It also leads to a number of applications in mathematical general relativity, numerical relativity, astrophysics, and quantum gravity. In this review, I will discuss the basic ideas and recent developments in this framework, and summarize some of its applications with an emphasis on numerical relativity.Comment: 14 pages, 2 figures. Based on a talk presented at the 18th International Conference on General Relativity and Gravitation, 8-13 July 2007, Sydney, Australi

Breathing Space Final Evaluation Report

Breathing Space was a women-centred project, funded by the Tampon Tax Fund through the Department of Digital Culture Media and Sport. It aimed to reduce distress and the harmful impact of domestic abuse on women and their children. The focus of this project was support for women who have suffered complex trauma and are experiencing difficulties in their lives as a result. WHM provided safe space for women to “stabilize”, helping women to access internal and external resources and develop stress management skills and so address the critical first stage of trauma recovery. Breathing Space ran from August 2017 until March 2020. This report documents the findings from an independent evaluation of Breathing Space, drawing upon qualitative and quantitative data collected throughout the delivery period of the project

The Key Evaluation Report

The Key Project received Big Lottery funding to continue its work in 2017, aiming to work with disadvantaged girls and young women at high risk of abuse aged between 13 and 25 within the Leeds area. The project is located within Women’s Health Matters, a charitable provider of gender-specific services in Leeds. This report presents the overall evaluation findings from a longitudinal co-produced model of data collection conducted by the Centre for Health Promotion Research, Leeds Beckett University

The Weight of Opinion - The early childhood sector's perceptions about childhood overweight and obesty

Early childhood is a critical time in a child’s development when the foundations for good or poor eating habits and self-regulation of appetite are laid. Because long day care centres and preschools structure the daily environment in which the children in their care play and learn, the early childhood sector can make an important contribution to preventing and (sometimes) dealing with childhood overweight and obesity. Whether through the direct provision of food at child care or rules/suggestions surrounding the food that children are to bring to preschool, they exert some control over what children consume while in their care. Similarly, they control the amount of active play time that is available during the day. Long day care centres and preschools may also incorporate messages about healthy eating and the benefits of active play into their curriculum, and may provide modelling of good eating habits by the teachers/workers during snack or meal times. They may also regulate the kinds of fundraising opportunities used to support their preschools/centres (e.g. no chocolates or donut fundraisers), and provide parents with information and support regarding the development of healthy habits. This report presents the findings from a series of in-depth interviews on the perceptions of early childhood staff about the issue of childhood overweight and obesity and their role in supporting healthy eating and active play.Interviews were conducted with eleven directors and staff members from four long day care centres and four preschools, located in three areas within metropolitan Sydney and one area in rural NSW. The results show that the early childhood educators recognise childhood overweight and obesity as a serious issue and appreciate the complexity of the causes of the increasing prevalence of overweight. They viewed these issues as part of their core mission as early childhood educators, and worked under a philosophy of close partnership with families (and, in some cases, with local health professionals). All of the participants also acknowledged that parents can be sensitive about their children’s weight, that there can be uncertainty surrounding definitions of overweight among young children, and that there can be emotions around the provision of food and children’s eating patterns. At the same time, interviewees recognised that the early childhood sector can only do so much by themselves and that their efforts need to be complemented by efforts to support parents and change cultural and environmental factors that make it difficult to eat healthy foods and get adequate physical activity, especially considering the fact that not all children have access to or participate in early childhood education. However, given the large proportion of children and parents who do have contact with the early childhood sector, the potential to strengthen the role of the sector in preventing childhood overweight and obesity and promoting healthy eating and active play was highlighted in the research. The interviewees gave practical suggestions for how that could occur. They wanted more early childhood-friendly games, activities, books, songs, and posters about healthy eating and physical activity, more resources they could give directly to parents, more guidance on optimal nutrition policies (for preschools), more training for themselves (including information on when to be concerned about children’s weight and what to do about it), and more access to health professionals who could come and speak to them and the parents.This research was funded by NSW Health and The Ross Family Trust. Principal Investigators: Dr Michael Booth and Lesley King. The authors would like to thank Louise Erickson for her valuable contribution to this project, as well as all the preschools and child care centres who participated in the study