The Method of Images in Cosmology

31 pages, 18 figures31 pages, 18 figuresWe apply the method of images to the exact initial data for cosmological models that contain a number of regularly arranged discrete masses. This allows us to join cosmological regions together by throats, and to construct wormholes in the initial data. These wormholes allow for the removal of the asymptotically flat "flange" regions that would otherwise exist on the far side of black holes. The method of images also provides us with a way to investigate the definition of mass is cosmology, and the cosmological consequences of the gravitational interaction energies between massive objects. We find evidence that the interaction energies within clusters of massive objects do indeed appear to contribute to the total energy budget in the cosmological regions of the space-time

Push-pull fatigue properties of wires in an iridium - 5% tungsten alloy

Introduction This memorandum reports a series of tests to determine the fatigue properties of an iridium - 5% tungsten alloy at 600°c and 700°C. A previous memorandum, Memo. Mat. 61, reports the fatigue properties at room temperature of the same alloy

Family and Peer Influences on Substance Attitudes and Use among Juvenile Justice-Involved Youth

Juvenile justice-involved youth experience high rates of substance use, which is concerning given associated negative consequences, including health and functional deficits. Family and peer factors are associated with a high risk of substance use among justice-involved youth. It is hypothesized that this risk process operates through pro-drug attitudes. However, limited research has been conducted on the mechanisms through which family and peer factors increase risk for substance use among juvenile justice involved youth. The current study examined both the direct and indirect effects of family and peer substance use on youth's substance use (alcohol and illicit drug use). We also examined whether this relationship differs by race. 226 detained youth (81.9% male; 74.3% Black) were recruited from an urban county in the Midwest and completed a clinical interview and substance use assessment battery. A direct effect of family/peer risk on illicit drug use was found for all youth, though the effect was stronger among White youth. Results also supported the indirect effect pathway from family/peer risk to both illicit drug use and alcohol use through pro-drug attitudes. This pathway did not vary by race. These findings suggest that interventions should focus on targeting both family/peer risk and pro-drug attitudes to reduce substance use. Given the racial difference in the direct effect of family/peer risk on illicit drug use, there may be other factors that influence risk more strongly for White youth, which warrants further investigation

Dynamics of a lattice Universe

We find a solution to Einstein field equations for a regular toroidal lattice of size L with equal masses M at the centre of each cell; this solution is exact at order M/L. Such a solution is convenient to study the dynamics of an assembly of galaxy-like objects. We find that the solution is expanding (or contracting) in exactly the same way as the solution of a Friedman-Lema\^itre-Robertson-Walker Universe with dust having the same average density as our model. This points towards the absence of backreaction in a Universe filled with an infinite number of objects, and this validates the fluid approximation, as far as dynamics is concerned, and at the level of approximation considered in this work.Comment: 14 pages. No figure. Accepted version for Classical and Quantum Gravit

Cosmological solutions with charged black holes

RB aknowledges support from the Higher Education Commission (HEC) of Pakistan, which provided funding to visit QMUL while this work was performed. TC and JD are supported by the STFC

Evaluating 802.11B Using Modular Theory

Recent advances in replicated technology and extensible information offer a viable alternative to local-area networks. In fact, few cyberneticists would disagree with the understanding of multicast frameworks. In this position paper we understand how red-black trees can be applied to the deployment of multicast methodologies

A quasi-static approach to structure formation in black hole universes

JD and TC both acknowledge support from the STFC under grant STFC ST/N504257/1

An economic analysis of hay harvesting and utilization using a simulation model, Station Bulletin, no.495

The Bulletin is a publication of the New Hampshire Agricultural Experiment Station, College of Life Sciences and Agriculture, University of New Hampshire, Durham, New Hampshire