Direct Determinations of the Redshift Behavior of the Pressure, Energy Density, and Equation of State of the Dark Energy and the Acceleration of the Universe

One of the goals of current cosmological studies is the determination of the expansion and acceleration rates of the universe as functions of redshift, and the determination of the properties of the dark energy that can explain these observations. Here the expansion and acceleration rates are determined directly from the data, without the need for the specification of a theory of gravity, and without adopting an a priori parameterization of the form or redshift evolution of the dark energy. We use the latest set of distances to SN standard candles from Riess et al. (2004), supplemented by data on radio galaxy standard ruler sizes, as described by Daly and Djorgovski (2003, 2004). We find that the universe transitions from acceleration to deceleration at a redshift of about 0.4. The standard "concordance model" provides a reasonably good fit to the dimensionless expansion rate as a function of redshift, though it fits the dimensionless acceleration rate as a function of redshift less well. The expansion and acceleration rates are then combined with a theory of gravity to determine the pressure, energy density, and equation of state of the dark energy as functions of redshift. Adopting General Relativity as the correct theory of gravity, the redshift trends for the pressure, energy density, and equation of state of the dark energy out to redshifts of about one are determined, and are found to be generally consistent with the concordance model.Comment: 8 pages, 5 figures. Invited presentation at Coral Gables 200

Metamorphism and its phases

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FRII radio sources in rich clusters of galaxies

A sample of FRII radio sources in rich clusters of galaxies, both at high (z\sim0.5) and low (z\sim0) redshift, has been constructed to study the effect of environment on radio sources. Comparisons are made between the properties of FRII sources in cluster and non-cluster environments, and between X-ray clusters with and without FRII sources. The principal results are the following: 1. Most low-redshift FRII sources in clusters appear to be similar to FRII sources in group or field environments in terms of radio power, optical properties of the host galaxy, and nonthermal pressure of the radio bridge. Most low-redshift clusters with FRII sources tend to lie at the lower end of cluster X-ray luminosity distribution, some having L_x comparable to FRII sources in non-cluster environments. 2. High-redshift FRII sources are all quite similar to each other irrespective of their environments. The nonthermal pressures of their radio bridges appear to be similar to those of low-redshift FRII's. 3. The nonthermal pressures of the bridges of FRII sources appear to be similar to the thermal pressures of the ICM around them. This result would allow FRII sources to be used as probes of their gaseous environments. The current data imply that the evolution in the clustering strength around FRII sources toward high-redshift is likely to be closely linked to an evolution of the state of the intracluster medium

Indigenous families and the welfare system: the Kuranda community case study, Stage Two

This discussion paper presents the results from the second year (Stage Two) of the Kuranda community case study for the project on Indigenous families and the welfare system. Twenty-nine key reference people were interviewed about the factors influencing the delivery of welfare income by government to Indigenous families for the care of children. Many of the key findings of the initial 1999 survey were confirmed in this follow-up study. Families and households remain highly dependent on income support via the CDEP scheme or benefits and pensions. The key role played by older women in the care of children was emphasised once again. The additional year of data enabled the documentation of the high level of mobility within the community. Between the 1999 and 2000 surveys, 84 individuals or 47 per cent of the 1999 survey participants had changed their place of residence. Some of these people moved as individuals and others as part of a family group. The results emphasise the importance of the extended family network in the care of children. The results raise a number of important issues for policy and service delivery. The fact that child-care is family-based rather than household-based needs to be recognised in the delivery of services to children. Many children have multiple carers who are in need of financial support for the period in which they are responsible for a child. There therefore needs to be flexibility in the arrangements so that the relevant family payments are going to the person actually caring for a child. The paper emphasises the need for a holistic approach to delivering assistance to children. This includes the importance of increasing the opportunities for employment and training among Indigenous adults, of providing recreational and support facilities for young people, and of facilitating the interaction between Indigenous people and the welfare system

Developing Interventions for Children's Exercise (DICE): a pilot evaluation of school-based exercise interventions for primary school children aged 7 to 8 years.

BACKGROUND: Developing Interventions for Children's Exercise (DICE) is an initiative aimed at determining effective school-based exercise programs. To assess feasibility, we conducted a pilot study of exercise sessions which varied in duration and frequency. METHODS: Exercise interventions were delivered to Year 3 pupils (age 7-8 years; n = 73) in primary schools within Yorkshire, UK. Evaluations were conducted using focus group sessions, questionnaires and observations. RESULTS: The study revealed positive aspects of all interventions, including favorable effects on children's concentration during lessons and identified the value of incorporation of the DICE concept into curriculum lessons. Children appeared enthused and reported well-being and enjoyment. Areas requiring attention were the need for appropriate timetabling of sessions and ensuring the availability of space. CONCLUSION: The concept and sessions were well-accepted by teachers who confirmed their full support of any future implementation There appears to be potential for the encouragement and empowerment of teachers to support physical activity and healthy school environments, and to take an interest in the health of their pupils. Ultimately, these findings should assist in the design of successful exercise interventions in the school setting

Change in the relative economic status of Indigenous males in the 1980s: Australia and the United States compared

The 1980s saw some significant changes in the income distribution in Australia and the United States of America (US). The purpose of this paper is to examine how these changes have affected the relative income status of Indigenous males in each country. In 1980, the average income of a Native American male was 58.3 per cent, and that of the average Australian Indigenous male was 50.5 per cent of their white counterparts. By the end of the decade, the relative income position of the two Indigenous groups had reversed. The average Native American male had an income equal to 48.2 per cent of white Americans and the average Indigenous Australian male had an income equal to 55.5 per cent of non-Indigenous Australian males. This reversal in relative positions involved swimming against the tide of a widening income distribution in Australia. Much of this improvement for Indigenous Australian males can be attributed to government policy initiatives, both those directed specifically toward Indigenous Australians and those of a more general nature in the area of welfare policy. Native Americans in the US have not received the same attention from government. It is, however, important to note that the employment rate among Native Americans has remained well above that of Indigenous Australian males, 60 per cent compared with 45 per cent. The Australian welfare system has played an important role in raising the relative income of Indigenous Australian males

Quintessence, Cosmology, and Fanaroff-Riley Type IIB Radio Galaxies

Fanaroff-Riley type IIb (FR IIb) radio galaxies provide a modified standard yardstick that allows constraints to be placed on global cosmological parameters. A sample of 20 FR IIb radio galaxies with redshifts between 0 and 2 are compared with the parent population of 70 radio galaxies to determine the coordinate distance to each source. The coordinate-distance determinations are used to constrain the current mean mass-energy density of quintessence $\Omega_q$, the equation of state of the quintessence w, and the current mean mass-energy density of nonrelativistic matter $\Omega_m$; zero space curvature is assumed. Radio galaxies alone indicate that the universe is currently accelerating in its expansion (with 84% confidence); most of the allowed parameter space falls within the accelerating universe region on the $\Omega_m$-w plane. This provides verification of the acceleration of the universe indicated by high-redshift supernovae and suggests that neither method is plagued by systematic errors. It is found that $\Omega_m$ must be less than about 0.5 and the equation of state w of the quintessence must lie between -0.25 and -2.5 at about 90% confidence. Fits of the radio galaxy data constrain the model parameter $\beta$, which describes a relation between the beam power of the active galactic nucleus (AGN) and the total energy expelled through large-scale jets. It is shown that the empirically determined model parameter is consistent with models in which the outflow results from the electromagnetic extraction of rotational energy from the central compact object. A specific relation between the strength of the magnetic field near the AGN and the spin angular momentum per unit mass of the central compact object is predicted