Trade Liberalisation, Efficiency and South Africa's Sugar Industry

This paper reports the results of a computable general equilibrium (CGE) analysis of the South African sugar industry. The study was inspired by analyses of the EU South Africa Free Trade Agreement that indicated the importance of sugar exports to the welfare gains from agricultural trade liberalisation and by the increasing pressure upon OECD countries to reform their sugar (trade) policies. In addition to the effects of trade liberalisation this study also considers the implications of increases in the efficiency with which sugarcane is converted to raw sugar, which is an important determinant of the competitiveness of sugar production and exports. The results indicate that there would be substantial welfare gains across all household groups and that overall agricultural producers in South Africa should benefit; however there are substantial variations in the impact upon agricultural producers in different provinces, with farmers in some provinces facing reductions in the profitability of farming

An investigation of the mechanics of tapered roller bearings

This investigation is concerned with the performance of tapered roller bearings under a pure thrust load. The design and development of a suitable test rig is described in some detail and the results of friction torque and film thickness measurements are compared with values predicted using recent elasto-hydrodynamic theory. It is shown that the reaction torque on the outer race may be ascribed to two principal sources. Firstly, to viscous rolling friction depending upon the product of speed and viscosity, and secondly to metallic hysteresis depending upon the load. If the maldistribution of load due to small dimensional differences in the rollers, is taken into consideration close agreement is obtained between the experimental and theoretical values of friction torque for a wide range of loads and speeds. At higher loads a third source becomes significant due to sliding between the ends of rollers and the lip of the inner race. A further important effect of the uneven loading of rollers is its influence on the life of a bearing. It is suggested that improved roller matching would result in an increase in bearing life. Measurements of race and cage speeds, taken throughout the investigation failed to detect any cage slip. Electrical resistance measurements made across the races confirm the presence of a lubricant film of a thickness which is consistent with theory. A visual display of the voltage drop indicated that the degree of asperity contact dependedupon the surface finish and the thickness of the oil film. An analysis of the dynamics of the tapered roller bearingshowed that although the geometry leads to a gyroscopic couple acting on the rollers, its magnitude is small and of little practical importance

Effect of Milk Yield, Sward Height and Concentrate Supplementation Level on Herbage Intake and Grazing Behaviour of Set-Stocked Dairy Cattle in Spring

An experiment was carried out in spring over 42 days, with 48 multiparous Holstein Friesian cows, to examine the interrelationship of milk yield level, sward height and concentrate level. Two initial milk yield groups of 21.3 and 35.5 kg/day, two range of compressed sward heights of 3 to 5 cm, and 7 to 9 cm , and three concentrate levels of 0 and 6 kg/day and ad libitum were evaluated in a factorial design. Multiple regression analyses were carried out relating intake and behavioural dependent variables to the independent variables initial milk yield (IMY), sward height (SH) and concentrate intake (CI).Total DM intake was highest for the high yielding group (P\u3c0.001) (16.4 and 19.6 s.e.d 0.65), and rate of intake (g DM/min) was higher (P\u3c0.001) (21.8 and 27.9 s.e.d. 1.91). Concentrates reduced rate of intake ( 31.4, 25.8, and 20.7 g DM/min s.e.d. 2.34). The multiple regression coefficients indicated that the herbage intake increased by 0.61 kg/day per 1 cm increase in sward height, reduced by 0.69 kg/day per kg increase in concentrate, and increased by 0.21 kg/day per kg increase in initial milk yield

Massive scalar field quasi-normal modes of higher dimensional black holes

We study quasinormal spectrum of massive scalar field in the $D$-dimensional black hole background. We found the qualitatively different dependence on the field mass of the fundamental modes for $D\geq6$. The behaviour of higher modes is qualitatively the same for all $D$. Thus for some particular values of mass (of the field and of the black hole) the spectrum has two dominating oscillations with a very long lifetime. Also we show that the asymptotically high overtones do not depend on the field mass. In addition, we present the generalisation of the Nollert improvement of the continued fraction technique for the numerical calculation of quasi-normal frequencies of $D$-dimensional black holes.Comment: 8 pages, 4 figures, misprints corrected, version to appear in Phys. Rev.

The size, concentration, and growth of biodiversity-conservation nonprofits

Nonprofit organizations play a critical role in efforts to conserve biodiversity. Their success in this regard will be determined in part by how effectively individual nonprofits and the sector as a whole are structured. One of the most fundamental questions about an organization’s structure is how large it should be, with the logical counterpart being how concentrated the whole sector should be. We review empirical patterns in the size, concentration, and growth of over 1700 biodiversity-conservation nonprofits registered for tax purposes in the United States within the context of relevant economic theory. Conservation-nonprofit sizes vary by six to seven orders of magnitude and are positively skewed. Larger nonprofits access more revenue streams and hold more of their assets in land and buildings than smaller or midsized nonprofits do. The size of conservation nonprofits varies with the ecological focus of the organization, but the growth rates of nonprofits do not

Transcriptional control mechanisms of genes of lipid and fatty acid metabolism in the Atlantic salmon (Salmo salar L.) established cell line, SHK-1

The regulatory control mechanisms of lipid and fatty acid metabolism were investigated in Atlantic salmon. We identified sterol regulatory element binding protein (SREBP) genes in salmon and characterised their response, and the response of potential target and other regulatory genes including liver X receptor (LXR), to cholesterol and long-chain polyunsaturated fatty acids (LC-PUFA) in the salmon established cell line, SHK-1. Two cDNAs for SREBPs homologous to mammalian SREBP-1 and SREBP-2 were characterised. We identified three groups of genes whose expression responded differently to the treatments. One group of genes, including cholesterol biosynthetic genes, showed increased expression in response to lipid depletion but supplementary cholesterol or LC-PUFA had no further effect. The expression of a second group of genes belonging to fatty acid biosynthetic pathways, included fatty acid synthase, Δ6 and Δ5 fatty acyl desaturases, also increased after lipid depletion but this was negated by cholesterol or by LC-PUFA supplementation. The expression of a third group of genes including acyl-CoA oxidase, HMG-CoA reductase and Elovl5 elongase was increased by cholesterol treatment but was not affected by lipid depletion or by LC-PUFA. This same pattern of expression was also shown by liver X receptor (LXR), indicating that acyl-CoA oxidase, HMG-CoA reductase and Elovl5 are possible direct targets of LXR. This suggests that salmon Elovl5 may be regulated differently from mammalian Elovl5, which is an indirect target of LXR, responding to LXR-dependent increases in SREBP-1

Quasi-Normal Modes of Brane-Localised Standard Model Fields II: Kerr Black Holes

This paper presents a comprehensive study of the fundamental quasinormal modes of all Standard Model fields propagating on a brane embedded in a higher-dimensional rotating black hole spacetime. The equations of motion for fields with spin $s=0, 1/2$ and 1 propagating in the induced-on-the-brane background are solved numerically, and the dependence of their QN spectra on the black hole angular momentum and dimensionality of spacetime is investigated. It is found that the brane-localised field perturbations are longer-lived when the higher-dimensional black hole rotates faster, while an increase in the number of transverse-to-the-brane dimensions reduces their lifetime. Finally, the quality factor $Q$, that determines the best oscillator among the different field perturbations, is investigated and found to depend on properties of both the particular field studied (spin, multipole numbers) and the gravitational background (dimensionality, black hole angular momentum number).Comment: 12 pages, 8 figures, typos corrected, version to appear in Phys. Rev.

Late-Time Tails in Gravitational Collapse of a Self-Interacting (Massive) Scalar-Field and Decay of a Self-Interacting Scalar Hair

We study analytically the initial value problem for a self-interacting (massive) scalar-field on a Reissner-Nordstr\"om spacetime. Following the no-hair theorem we examine the dynamical physical mechanism by which the self-interacting (SI) hair decays. We show that the intermediate asymptotic behaviour of SI perturbations is dominated by an oscillatory inverse power-law decaying tail. We show that at late-times the decay of a SI hair is slower than any power-law. We confirm our analytical results by numerical simulations.Comment: 16 pages, 3 ps figures, Revte