Generalized Lemaitre-Tolman-Bondi Solutions with Pressure

Utilizing the ADM equations, we derive a metric and reduced field equations describing a general, spherically symmetric perfect fluid. The metric describes both the interior perfect fluid region and exterior vacuum Schwarzschild spacetime in a single coordinate patch. The exterior spacetime is in generalized Painleve-Gullstrand coordinates which is an infinite class of coordinate systems. In the static limit the system reduces to a Tolman-Oppenheimer-Volkoff equation on the interior with the exterior in Schwarzschild coordinates. We show the coordinate transformation for the non-static cases to comoving coordinates, where the metric is seen to be a direct generalization of the Lemaitre-Tolman-Bondi spacetime to include pressures.Comment: Accepted for publication by Physical Reviews

Depressive illness in institutionalised older people in Malta

Depression in older persons is associated with being placed in a nursing home. Depression is linked to increased medical morbidity in nursing home residents. 150 patients living in two nursing homes in Malta were included in the study. The geriatric depression scale was used to identify depression. Data for risk factors for depression and management of residents for this pathology was also collected. 67.3% (p value <0.01) were found to be depressed. 12% of the total population had major depression while 55.3% had minor depression. Only 40% of those diagnosed with depression in this study had been so diagnosed prior to the study. Significant associations included low Barthel scores, loneliness, being currently in pain, taking several medications, being widowed and having osteoarthritis. The study also showed that those residents already diagnosed with depression were being treated inappropriately with low prescription levels of antidepressants (40.6%). : Results show that depression in nursing home residents is highly prevalent and under diagnosed. There is also a lack of proper treatment in those identified with depression. There is a need for further research to develop intervention and management strategies for depression that is specifically tailored to meet the needs of the frail nursing home population.peer-reviewe

Automatic application object migration in sensor networks

Object migration in wireless sensor networks has the potential to reduce energy consumption for a wireless sensor network mesh. Automated migration reduces the need for the programmer to perform manual static analysis to find an efficient layout solution. Instead, the system can self-optimise and adjust to changing conditions. This paper describes an automated, transparent object migration system for wireless sensor networks, implemented on a micro Java virtual machine. The migration system moves objects at runtime around the sensor mesh to reduce communication overheads. The movement of objects is transparent to the application developer. Automated transparent object migration is a core component of Hydra, a distributed operating system for wireless sensor networks that is currently under development. Performance of the system under a complex performance test scenario using a real-world dataset of seismic events is described. The results show that under both simple and complex conditions the migration technique can result in lower data traffic and consequently lower overall energy cost

Alternative Measures of Homeownership Gaps Across Segregated Neighboorhoods

The dramatic rise in the U.S. homeownership rate from 64% in 1996 to almost 70% in 2005 has prompted increased attention to the relation between homeownership and demographic characteristics of households. The recent rise and sharp decline of subprime lending will likely spur interest in the relation between credit conditions and homeownership gaps. Statistical analysis of these differences or “gaps” in homeownership between white and minority households follows what has become a highly stylized pattern. Essentially differences in homeownership at the mean or the conditional mean between groups are compared. This study implements a new decomposition technique that identifies the unexplained portion of the gap not only at the mean, but at every percentile of the distribution of the dependent variable. This method was first proposed by Machado and Mata (2005), extended by Albrecht et al. (2006), and has been used in several applications in labor economics. Similar to the labor market application, differences in homeownership gaps at the mean reflect a combination of non- significant differences at the upper end and much larger gaps at the lowest end of the distribution of homeowners.Homeownership, Race, Quantile regression decomposition

Integration, Specialization, and the Adjustment

In the United States, many industries have a Silicon Valley-type geographic localization. In Europe, these same industries often have four or more major centers of production. This difference is presumably the result of the formal and informal trade barriers that have divided the European market. With the growing integration of that market, however, there is the possibility that Europe will develop an American-style economic geography. This paper uses a theoretical model of industrial localization to demonstrate this possibility, and to show the possible transition costs associated with this shift.

Working as one: a road map to disaster resilience for Australia

This report offers a roadmap for enhancing Australia’s disaster resilience, building on the 2011 National Strategy for Disaster Resilience. It includes a snapshot of relevant issues and current resilience efforts in Australia, outlining key challenges and opportunities. Overview Natural disasters cause widespread disruption, costing the Australian economy $6.3 billion per year, and those costs are projected to rise incrementally to$23 billion by 2050. With more frequent natural disasters with greater consequences, Australian communities need the ability to prepare and plan for them, absorb and recover from them, and adapt more successfully to their effects. Enhancing Australian resilience will allow us to better anticipate disasters and assist in planning to reduce losses, rather than just waiting for the next king hit and paying for it afterwards. This report offers a roadmap for enhancing Australia’s disaster resilience, building on the 2011 National Strategy for Disaster Resilience. It includes a snapshot of relevant issues and current resilience efforts in Australia, outlining key challenges and opportunities. The report sets out 11 recommendations to help guide Australia towards increasing national resilience, from individuals and local communities through to state and federal agencies

Yesterday, today and tomorrow: A perspective of CFD at NASA's Ames Research Center

The opportunity to reflect on the computational fluid dynamics (CFD) progam at the NASA Ames Research Center (its beginning, its present state, and its direction for the future) is afforded. Essential elements of the research program during each period are reviewed, including people, facilities, and research problems. The burgeoning role that CFD is playing in the aerospace business is discussed, as is the necessity for validated CFD tools. The current aeronautical position of this country is assessed, as are revolutionary goals to help maintain its aeronautical supremacy in the world

An analysis of preferences of sixth grade elementary pupils in the field of language.

Thesis (Ed.M.)--Boston Universit