Effects of tangential velocity in the reactive relativistic Riemann problem

Type I X-ray bursts are thermonuclear burning events which occur on the surfaces of accreting neutron stars. Burning begins in a localised spot in the star's ocean layer before propagating across the entire surface as a deflagration. On the scale of the entire star, the burning front can be thought of as discontinuity. To model this, we investigated the reactive Riemann problem for relativistic deflagrations and detonations and developed a numerical solver. Unlike for the Newtonian Riemann problem, where only the velocity perpendicular to the interface is relevant, in the relativistic case the tangential velocity becomes coupled through the Lorentz factor and can alter the waves present in the solution. We investigated whether a fast tangential velocity may be able to cause a deflagration wave to transition to a detonation. We found that such a transition is possible, but only for tangential velocities that are a significant fraction of the speed of light or for systems already on the verge of transitioning. Consequently, it is highly unlikely that this transition would occur for a burning front in a neutron star ocean without significant contributions from additional multidimensional effects.Comment: 16 pages, 10 figures, Accepted for publication in Ap

A comparative analysis of the industrial relations experiences of Indigenous and other Australian workers

Indigenous employment policy needs to be informed by a good understanding of the industrial relations culture of workplaces. For example, the local industrial relations environment is a major factor determining wages, job conditions and the quality of workplace life. This study contrasts the experience of industrial relations for Indigenous and non-Indigenous workers in workplaces with some Indigenous employees. The Australian Workplace Industrial Relations Survey (AWIRS) 1995 is the first publicly released dataset that permits analysts to directly examine the industrial relations environment in firms that employ Indigenous Australians. Information from the AWIRS employee survey and AWIRS Employee Relations Managers survey are used in the analysis

Industrial relations in workplaces employing Indigenous Australians

The enactment of the Workplace Relations Act 1996 by the Howard Government represented an acceleration in the pace of industrial relations reform. Amid these significant and widespread legislative developments, little attention was paid to the plight of groups traditionally disadvantaged in the labour market-including Indigenous people. The Australian Workplace Industrial Relations Survey (AWIRS) 1995 is the first publicly released data set that permits analysts to directly examine the industrial relations environment in firms that employ Indigenous Australians. Information from the AWIRS employee survey and AWIRS Employee Relations Managers survey are used in the analysis

Work and welfare for Indigenous Australians

An issue frequently raised in the literature on the economic status of Aboriginal people is the importance of welfare transfers as a source of income, yet there is very little aggregate information documenting this. The purpose of this paper is to present the available evidence from the Population Census and administrative data sources. One estimate is based on the share of total individual income coming from those in employment. Results from 1976 and 1991 show that for Aboriginal people, a smaller share of total individual income came from this source than was the case for other Australians. The last time a question on sources of income was included in a census was in 1976, and the comparison of the numbers receiving a government pension or benefit presented here shows that a larger proportion of Aboriginal people were in receipt of these payments than other Australians. The conclusions based on more recent administrative data are less clear because of the difficulties faced in identifying Aboriginal people and in combining figures from different sources. Nevertheless, the figures are consistent with a broad conclusion of higher levels of welfare receipt among Aboriginal people. The relatively high levels of welfare receipt reflect important underlying problems facing Aboriginal people; high levels of unemployment, poor health and the high incidence of sole parenthood. The paper concludes by stressing the importance of addressing these issues directly

Industrial relations in workplaces employing Indigenous Australians

The enactment of the Workplace Relations Act 1996 by the Howard Government represented an acceleration in the pace of industrial relations reform. Amid these significant and widespread legislative developments, little attention was paid to the plight of groups traditionally disadvantaged in the labour market-including Indigenous people. The Australian Workplace Industrial Relations Survey (AWIRS) 1995 is the first publicly released data set that permits analysts to directly examine the industrial relations environment in firms that employ Indigenous Australians. Information from the AWIRS employee survey and AWIRS Employee Relations Managers survey are used in the analysis

The impact of the welfare state on the economic status of Indigenous Australian women

This paper uses census data and Department of Social Security (DSS) administrative records to examine the role of social security income in explaining the growth and relative improvement in the income status of Indigenous Australian women. The real median income of Indigenous women was 81 per cent of that of non-Indigenous women in 1991 compared with 74 per cent in 1976. Much of the change has come from an improvement in the position of Indigenous women who were not in employment. The paper argues that much of this improvement can be attributed to increased access to social security benefits for Indigenous women and therefore needs to be qualified by the circumstances in which Indigenous women live. A mid-term review of the Aboriginal Employment Development Policy (AEDP) has recently been completed. While much of the associated policy rhetoric and assessment of policy outcomes has been aimed at the national level, the fiscal environment in which AEDP goals are to be achieved is invariably one of regional labour markets and administrative systems operating in the economic context of States and Territories. In view of this reality, this paper responds to a need for regional-level analyses of change in the economic status of Indigenous people compared to that of non-Indigenous people in each State and Territory. Using 1986 and 1991 Census-based social indicators for the Northern Territory, attention is focused on relative shifts in population growth and intra-State distribution, labour force and income status, and levels of welfare dependency (measured as non-employment income). A major finding is that while the gap in labour force status between Indigenous and non-Indigenous people has narrowed, the relative income status and level of welfare dependency of Indigenous people has worsened. This suggests that increased emphasis on the quality of AEDP outcomes, and not just quantity, will be necessary if the overall aims of the AEDP are to be accomplished

Indigenous Australians and the labour market: Issues for the union movement in the 1990s

The Aboriginal Employment Development Policy (AEDP) aims to achieve economic equality between Indigenous and other Australians by the year 2000 via three goals: employment equality, income equality and commensurate levels of welfare dependence. Achieving employment equality, in statistical terms, for working-aged Indigenous Australians will require an increase in the employment rate from 27 percent of those aged 15-64 years to 63 percent. The relatively low labour force participation of Indigenous Australians will require a simultaneous policy focus. In 1991, only 57 percent of the working-age Indigenous population was in the formal labour market compared with 71 per cent of the total population. The achievement of income equality will require an increase in mean annual individual income by over 50 per cent. This paper addresses some of the issues which affect Aboriginal and Torres Strait Islander people in the labour market. Some possible options available to the union movement to assist in improving their performance in the formal labour market in a manner commensurate with broad AEDP goals, are canvassed. The particular focus here is on how unions can assist in increasing formal employment and attendant income levels for Indigenous Australians

Changes in Understorey Pasture Composition in Agroforestry Regimes in New Zealand

Long term Agroforestry trials were established in the North and South Islands of New Zealand between 1971-76. They compared a range of final tree stockings of Pinus radiata planted into pasture with open pasture control plots and were measured for tree growth parameters and agricultural production. This paper presents the results of pasture species changes over the period of tree age 10-22 years. Pasture species composition under Pinus radiata changed with time, dependent primarily on the rate of canopy closure. Changes occurred relatively rapidly in high tree stocked areas of 400 stems per hectare (sph) in the North Island trials where ryegrass (Lolium perenne L) and white clover (Trifolium repens L) were replaced with annual and native grass until canopy closure resulted in loss of all pasture by tree age 13 years. In lower tree stocked areas these changes occurred more slowly so that by tree age 19 years, pasture species such as Yorkshire Fog (Holcus lanatus) and annual grasses (Poa Species) still contributed to the ground cover. In the South Island trials, pasture persisted longer into the tree rotation. Open pasture (0 sph) retained similar pasture species to that at the trial commencement in all locations. A point analysis technique at one North Island site gave a good measure of ground surface cover over time

The Effects of Shelterbelts on Adjacent Pastures and Soils in a Temperate Climate

Two trials were conducted to differentiate the direct (exposure) from the indirect (modified soil fertility due to nutrient transfer by grazing animals) effects of farm shelterbelts on associated pasture growth.Soil from close to “unmanaged”shelterbelts with dense shelter to ground level had relatively high potassium (K) levels and, in a glasshouse situation, provided more pasture growth than soil from further distances, or from adjacent to “managed” shelterbelts. Pasture grown in boxes of a common soil implanted at increasing distances from a shelterbelt also produced highest growth rates close to shelter. These results generally explain the pattern of resident pasture growth, except for the closest (5 metre) distance which had the lowest pasture growth.This appears related to relatively low soil moisture levels at these sites, due either to rain shelter or tree root competition effects