Efimov Trimers in a Harmonic Potential

We study the Efimov effect in a harmonic oscillator in the hyperspherical formulation, and show how a reduced model allows for a description that is a generalization of the Efimov effect in free space and leads to results that are easily interpreted. Efimov physics may be observed by varying the value of the scattering length, since in the regime where the trimers have a mixed harmonic oscillator and Efimov character, the inelastic properties of these states are still manageable. The model also allows for the study of non-universal Efimov trimers by including the effective range scattering parameter. While we find that in a certain regime the effective range parameter can take over the role of the three-body parameter, interestingly, we obtain a numerical relationship between these two parameters different from what was found in other models.Comment: 15 pages, 9 figure

The Motivational Structure of Appreciation

On a widely held view in aesthetics, appreciation requires disinterested attention. George Dickie famously criticized a version of this view championed by the aesthetic attitude theorists. I revisit his criticisms and extract an overlooked challenge for accounts that seek to characterize appreciative engagement in terms of distinctive motivation: at minimum, the motivational profile such accounts propose must make a difference to how appreciative episodes unfold over time. I then develop a proposal to meet this challenge by drawing an analogy between how attention is guided in appreciation and how practical action is guided in ‘striving play’—a mode of game play recently foregrounded in the philosophy of games. On the resulting account, appreciation involves an ‘inverted’ motivational structure: the appreciating agent's attention is guided by cognitive goals taken up instrumentally, for the sake of the cognitive activity that results from attending under the guidance of those goals

Fiscal incidence of social spending in South Africa, 2006

This paper presents the findings of a study undertaken for the South African National Treasury regarding the expenditure incidence of social spending in South Africa in 2006, and also regarding changes in incidence in the period following democratisation. Concentration ratios and concentration curves show that there have been considerable shifts in social spending incidence in the period 1995 (the year after democracy) and 2006, the most recent observation. In particular, social spending grants have become a major tool of targeting resources to the poor. Although the poor now get considerably more of social spending than their population share, the very skew underlying income distribution means that the post-fiscal situation still is one with great inequality. Moreover, evidence is presented that spending efficiency for social spending is low, thus there is only a tenuous link between social spending and social outcomes. Thus great shifts in social spending have had a limited impact on poverty and inequality in South Africa.Fiscal incidence, Social spending, Poverty, Inequality, South Africa

Issues in South African Social Security

This paper, originally written at the time of the political transition, provides an overview of social security issues at that time. A sustained improvement in the living standards of the poor requires economic growth and investment in human capital to allow the poor to benefit from that growth, but a social safety net is also necessary for those who do not yet share in those benefits and to safeguard those who do against contingencies such as unemployment, old age and illness. In South African, too little attention was paid by social scientists to social security issues before the political transition, with regard to both social assistance and social (occupational) insurance and the link between them.social security, South Africa

Current poverty and income distribution in the context of South African history

This paper describes and analyses current poverty and income distribution in South Africa, with a central concern the relationship between poverty, inequality and growth. The paper also investigates patterns of and trends in poverty and income distribution, a literature with a long and distinguished history. Drawing from recent literature in this regard, the paper shows that the labour market – rather than access to wealth or to political and fiscal power – currently sets the limits to redistribution. Wage inequality, deeply rooted in South Africa’s history, plays a central role in overall income distribution, and patterns of human capital development are fundamental to the future growth path and therefore to poverty and income distribution. The paper therefore concludes that reducing inequality substantially is currently unlikely without a massive increase in the human capital of those presently poor, but that prospects in this regard are inauspicious.South Africa, poverty, income distribution, labour market

Total control over ultracold interactions via electric and magnetic fields

The scattering length is commonly used to characterize the strength of ultracold atomic interactions, since it is the leading parameter in the low-energy expansion of the scattering phase shift. Its value can be modified via a magnetic field, by using a Feshbach resonance. However, the effective range term, which is the second parameter in the phase shift expansion, determines the width of the resonance and gives rise to important properties of ultracold gases. Independent control over this parameter is not possible by using a magnetic field only. We demonstrate that a combination of magnetic and electric fields can be used to get independent control over both parameters, which leads to full control over elastic ultracold interactions.Comment: 4 pages, 3 figure

Agricultural Globalization in Developing Countries: Rules, Rationales and Results

This paper aims to provide a descriptive and analytical account of the extent to which agriculture in the developing economies has become integrated with external markets. For most developing economies (DEs), the 1980s were a time of crisis when liberal reforms, including domestic and external liberalization of agriculture, were also initiated. This was followed by the coming into force of the Agreement on Agriculture under WTO aegis. The evidence on trade flows does indicate increased agricultural globalization in developing economies (DEs) following these regime shifts. But increased trade flows have not been accompanied by relative price convergence as between the DEs and the advanced economies (AEs) suggesting both that the policy shifts have been asymmetric and that significant parts of agricultural trade between North and South remain complementary rather than, as is often assumed, competitive. Moreover, the “fallacy of composition”, implicit in any global imposition of trade liberalization and not confined to primary products as such, also seems to have been at work for most of the period. At the same time, the threat of higher consumer prices (especially for the poor and vulnerable in both importing and exporting DEs) looms large. Its impact will be felt as and when production and export subsidies in the AEs are dismantled. Meanwhile, the regime shifts seem to have induced, on the one hand, excessive faith in the efficacy of agricultural prices to produce agricultural supply response and, on the other, reduced fiscal and organizational capacities to provide public agricultural inputs and services. These conclusions are consonant with a structuralist understanding of global trade and production possibilities that DEs confront.

Trapped electrons in the quantum degenerate regime

A full strength Coulomb interaction between trapped electrons can be felt only in absence of a neutralizing background. In order to study quantum degenerate electrons without such a background, an external trap is needed to compensate for the strong electronic repulsion. As a basic model for such a system, we study a trapped electron pair in a harmonic trap with an explicit inclusion of its Coulomb interaction. We find the eigenenergy of the ground state, confirming earlier work in the context of harmonium. We extend this to a complete set of properly scaled energies for any value of the trapping strength, including the excited states. The problem is solved either numerically or by making harmonic approximations to the potential. As function of the trapping strength a crossover can be made from the strongly to the weakly-coupled regime, and we show that in both regimes perturbative methods based on a pair-wise electron description would be effective for a many-particle trapped electron system, which resembles a Wigner crystal in the ground state of the strongly coupled limit.Comment: 6 pages, 3 figure

The demand for health care in South Africa

Supply-side solutions to health-care provision dominate the South African debate about health care. These solutions are often premised on views that health resources are too concentrated in the private health sector – which supposedly serves only a small minority of the population – and thus public sector provision needs to be expanded. We argue that this rests on a lack of understanding of the nature of the demand for health services. This paper estimates the determinants of the demand for health care using a multinomial logit estimation. It is found that three categories of factors influence the demand for health care. Firstly, demographic and locational variables are significant (e.g. income group, race and where the respondent lives). Secondly, the characteristics of the care provided are important (e.g. cost and distance from the respondent). Finally, the characteristics of the illness (such as its severity) are important. Overall, private health care plays a surprisingly large role in the health care decisions of all South Africans – even poor respondents reveal a clear preference for private health care, despite constraints of money and access. This dominance of the demand for private health care is likely to increase with rising incomes, or if all health services were to receive a similar subsidy (e.g. from mooted medical insurance-type schemes). On a policy level, this would indicate that greater attention should perhaps be given to health demand in considering policy alternatives.health care, South Africa

Consumption patterns and the black middle class: The role of assets

Black consumption patterns differ from those of whites, even when considering income levels and household size. This applies particularly to the black middle class, the subject of intense public interest. This paper postulates that this difference results not from cultural differences in taste for middle class goods, but from an asset deficit experienced by blacks. We test this hypothesis using regression analysis based on the 2000 Income and Expenditure Survey. Once assets are considered, consumption of middle class goods by blacks even exceeds those of whites. One would then expect blacks to exhibit, compared to whites, (i) an asset deficit, (ii) an asset preference in purchases (to reduce the deficit), and (iii) a lag in consuming other middle class goods (if the asset deficit is not considered). Descriptive evidence, mainly graphical, from the All Media and Products Survey (AMPS) of 2004 provides support for the main hypothesis. This implies that, for black accruals to the middle class, a stage of asset accumulation would precede a stage of middle class consumption. But once assets have been acquired, the shift in consumption may be quite rapid. There may therefore remain two distinct groups of black middle class consumers: The established middle class (currently still quite small), who have accumulated assets and whose consumption patterns therefore would resemble those of whites; and the new middle class, who may prefer spending to acquire assets.Market definition, Delineation, Quantitative, Stationarity tests, Prices, Geographic, SSNIP, Hypothetical monopolist, Competition, Unit root, Price ratio, Antitrust