6,007 research outputs found
Bio-economic evaluation of pasture-cropping, a novel system of integrating perennial pastures and crops on crop-livestock farms
Pasture-cropping is a novel approach to increase the area of perennial crops in mixed sheep and cropping systems. It involves planting annual cereals directly into a living perennial pasture. There is interest in subtropical grasses as they are winter dormant and their growth profile is potentially well suited to pasture-cropping. However, a wide range of factors can affect the uptake of such systems. This paper assesses the relative importance of factors that can influence decisions to introduce pasture-cropping. In this paper the research question is: what factors predispose a farm to take up a new technology such as (1) subtropical grass and (2) subtropical grass that is pasture-cropped. The analysis uses the MIDAS model of a central wheatbelt farm in Western Australia. The results suggest the adoption of subtropical grasses is likely to be strongly influenced by soil mix; feed quality; and whether the farm is predominantly grazing or cropping and by the presence of meat versus wool producing animals. The same factors are relevant for subtropical grass that is pasture-cropped but in addition yield penalties due to competition between the host perennial and the companion cereal become important. The results suggest the level of forage production by subtropical grass is less important but this factor is likely to become more important if feed quality can be improved.Environmental Economics and Policy,
Finite element analysis applied to redesign of submerged entry nozzles for steelmaking
The production of steel by continuous casting is facilitated by the use of refractory hollow-ware components. A critical component in this process is the submerged entry nozzle (SEN). The normal operating conditions of the SEN are arduous, involving large temperature gradients and exposure to mechanical forces arising from the flow of molten steel; experimental development of the components is challenging in so hazardous an environment. The effects of the thermal stress conditions in relation to a well-tried design were therefore simulated using a finite element analysis approach. It was concluded from analyses that failures of the type being experienced are caused by the large temperature gradient within the nozzle. The analyses pointed towards a supported shoulder area of the nozzle being most vulnerable to failure and practical in-service experience confirmed this. As a direct consequence of the investigation, design modifications, incorporating changes to both the internal geometry and to the nature of the intermediate support material, were implemented, thereby substantially reducing the stresses within the Al2O3/graphite ceramic liner. Industrial trials of this modified design established that the component reliability would be significantly improved and the design has now been implemented in series production
The Australian Charter of Employment Rights: The missing dimensions
Just prior to the 2007 General Election, a group of labour lawyers and economists, broadly sympathetic to the Labor Party, produced a Charter of Employment Rights. This article examines the Charter's proposals and its underlying framework, and suggests significant aspects of work and labour have been omitted. It contends that the Charter would have been improved if it had not retained an artificially stretched definition of workers as employees, in which the only relationship worthy of inclusion in a Charter is that between the direct employer and employee. The framework and language of the Charter convey a paternalistic approach and an outdated focus on industrial labour, while ignoring aspects of the emerging global system of work linked to the concept of occupation
Knowledge of Objective 'Oughts': Monotonicity and the New Miners Puzzle
In the classic Miners case, an agent subjectively ought to do what they know is objectively wrong. This case shows that the subjective and objective âoughtsâ are somewhat independent. But there remains a powerful intuition that the guidance of objective âoughtsâ is more authoritativeâso long as we know what they tell us. We argue that this intuition must be given up in light of a monotonicity principle, which undercuts the rationale for saying that objective âoughtsâ are an authoritative guide for agents and advisors
Interactions of asbestos-activated macrophages with an experimental fibrosarcoma
Supernatants from in vivo asbestos-activated macrophages failed to show any cytostatic activity against a syngeneic fibrosarcoma cell line in vitro. UICC chrysotile-induced peritoneal exudate cells also failed to demonstrate any growth inhibitory effect on the same cells in Winn assays of tumor growth. Mixing UICC crocidolite with inoculated tumor cells resulted in a dose-dependent inhibition of tumor growth; this could, however, be explained by a direct cytostatic effect on the tumor cells of high doses of crocidolite, which was observed in vitro
Numerical loop quantum cosmology: an overview
A brief review of various numerical techniques used in loop quantum cosmology
and results is presented. These include the way extensive numerical simulations
shed insights on the resolution of classical singularities, resulting in the
key prediction of the bounce at the Planck scale in different models, and the
numerical methods used to analyze the properties of the quantum difference
operator and the von Neumann stability issues. Using the quantization of a
massless scalar field in an isotropic spacetime as a template, an attempt is
made to highlight the complementarity of different methods to gain
understanding of the new physics emerging from the quantum theory. Open
directions which need to be explored with more refined numerical methods are
discussed.Comment: 33 Pages, 4 figures. Invited contribution to appear in Classical and
Quantum Gravity special issue on Non-Astrophysical Numerical Relativit
Brayton-cycle radioisotope heat source design study. Phase I - /Conceptual design/ report
Conceptual designs for radioisotope heat source systems to provide 25 kW thermal power to Brayton cycle power conversion system for space application
Surface terms, Asymptotics and Thermodynamics of the Holst Action
We consider a first order formalism for general relativity derived from the
Holst action. This action is obtained from the standard Palatini-Hilbert form
by adding a topological-like term and can be taken as the starting point for
loop quantum gravity and spin foam models. The equations of motion derived from
the Holst action are, nevertheless, the same as in the Palatini formulation.
Here we study the form of the surface terms of the action for general
boundaries as well as the symplectic current in the covariant formulation of
the theory. Furthermore, we analyze the behavior of the surface terms in
asymptotically flat space-times. We show that the contribution to the
symplectic structure from the Holst term vanishes and one obtains the same
asymptotic expressions as in the Palatini action. It then follows that the
asymptotic Poincare symmetries and conserved quantities such as energy, linear
momentum and relativistic angular momentum found here are equivalent to those
obtained from the standard Arnowitt, Deser and Misner formalism. Finally, we
consider the Euclidean approach to black hole thermodynamics and show that the
on-shell Holst action, when evaluated on some static solutions containing
horizons, yields the standard thermodynamical relations.Comment: 16 page
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