Unemployment in South Africa: The nature of the beast

Unemployment in South Africa is so widespread that it demands an explanation. This paper examines two questions about South African unemployment. Firstly, why do the unemployed not enter the informal sector, as is common in other developing countries? Secondly, why do the unemployed not enter wage employment more readily? The findings provide little support for the idea that unemployed people choose to be unemployed: the unemployed are substantially worse off, and less satisfied with their quality of life, than they would be if informally employed. Various impediments to entry into the informal sector increase open unemployment. The test of the hypothesis that the unemployed have unrealistically high wage aspirations suggests that the commonly reported high reservation wages (relative to predicted wages) are not to be interpreted as reflecting unwillingness to work.

Are searching and non-searching unemployment distinct states when unemployment is high? The case of South Africa

Broadly and narrowly measured unemployment rates differ very markedly in certain countries, and the measure chosen to be the ‘official’ unemployment rate affects perceptions about the extent of the problem. The appropriate measure of the unemployment rate depends on whether jobless persons who say they want work but who are not actively searching should be regarded as part of the labour force. This paper examines whether the non-searching-unemployed state is distinct from the searching-unemployed state in a developing country - South Africa - where the broad unemployment rate and the gap between the broad and narrow rates are both very high. It asks whether lack of job-search among jobless persons claiming to want work is an outcome of tastes or of constraints. It finds evidence in support of adopting the broad definition.

Unemployment and wages in South Africa: A spatial approach

A large amount of recent evidence finds a negative relationship between local unemployment and wages in OECD countries, a relationship christened a ‘wage curve’. This contradicts the conventional model of the labour market in which high unemployment regions have higher wages to compensate for search and other costs. This paper discovers a wage curve in South Africa, a country with several times the typical unemployment rate of OECD countries. The wage curve elasticity in South Africa is similar to that in OECD countries (-0.1) but persists over a much larger range of unemployment rates, implying that unemployment can have a large impact on wages in South Africa. However, this wage flexibility does not extend to union wages which are well insulated from local unemployment conditions. The results here also shed light on the segmentation of the labour market based on labour immobility and on the debate about the appropriate definition of unemployment in South Africa.wages, unemployment, wage curve, South Africa

Theoretical HeI Line Intensities in Gaseous Nebulae: NGC 1976, 6572 and IC 4997

Smits has recently calculated theoretical He I intensities for a large number of lines for conditions appropriate to gaseous nebulae. These are likely to remain the definitive calculations for some time to come. A comparison of these line ratios with observed values in three nebulae reveals some discrepancies. We show that these discrepancies are reduced when collisional effects from the metastable 23S level are included, and that it is not necessary to invoke an unknown depopulation mechanism for the He I23S level

Grains in Ionized Nebulae. II. Heavy-Element Depletion

The presence of grains in gaseous nebulae can have significant effects on the thermal balance and radiative line transfer in these objects. The depletion of condensable elements onto grains provides evidence that dust exists in the ionized regions of nebulae. In this paper, we consider the elements Sc, Ti, V, and Cr, all of which are strongly depleted in the general interstellar medium. We construct simple three-level atoms for several ions of these elements, and incorporate them into our photoionization code CLOUDY. For both a model planetary nebula and a model H II region, we find that several lines of these elements should be easily detectable, provided that their gas-phase abundances are solar. This suggests that these elements are strongly depleted in ionized regions of these nebulae. We quantify these expectations by defining and comparing line ratios which are relatively insensitive to stellar and nebular parameters with recently measured intensities of [V IV], [Cr IV], and [Cr V] lines in NGC 7027. We encourage both further theoretical and observational work on these ions

Collisional Effects in He I: An Observational Analysis

Accurate and reliable helium abundances can test modern theories of galactic and primordial nucleosynthesis. Unfortunately, there is some question whether current theory can account for collisional contributions to He I. We present new observations of two planetary nebulae (PNs) in the range λ850-λ9650, which we use to assess the importance of collisonal effects in the He I spectrum. The first object, NGC 7027, is expected to show relatively strong collisional enhancement, while the second, NGC 7026, should display only small effects. We derive new collision-to-recombination correction factors, based on new collision strengths from the 29-state quantal calculation of He I extending to n = 5. Our results show that the correction factors based on \u27standard\u27 theory are correct, but that the errors acquired in such an observational analysis are appreciable. We find no convincing observational evidence for the existence of an unknown agent depopulating the 23S state in Pns

Temperature Fluctuations in Photoionized Nebulae. II. The Effect of Inhomogeneous Abundances

Recent abundance determinations based on recombination lines in several emission-line nebulae yield ionic abundances several times larger than those derived from forbidden lines. These results cast uncertainty over all abundance determinations in such objects. One possible explanation for these discrepancies frequently cited in the literature is the presence of chemical inhomogeneities. We have run a series of photoionization models to examine what effect such inhomogeneities will have on the resulting temperature structure of nebulae. We then derive abundances from these models, utilizing Peimbert\u27s t2 formalism. Our results suggest that, although chemical inhomogeneities may produce nonnegligible biases in abundance determinations in a small number of objects, it is highly unlikely that they can resolve the observed discrepancy for most nebulae. We also stress the importance of continued high spatial resolution observations in nebulae to clarify the presence or absence of inhomogeneities in gaseous nebulae

Rate Coefficients for Charge Transfer between Hydrogen and the First 30 Elements

We present analytic fits to charge exchange rate coefficients over the full range of temperatures which occurs in photoionized or shock-heated plasmas. We consider reactions between neutral hydrogen and all elements with parent ion charge q = 1-4 up to Z = 30. Many rates were obtained from various sources in the literature. For reactions for which no data were available, we calculated rates using the Landau-Zener formalism. For these new reactions, we tabulate both total and state-specific rate coefficients. Ml are fitted with a consistent, accurate formula. These fits may be incorporated easily into spectral synthesis codes, and we make available an electronic form of our results. We draw attention to the most important reactions without high-quality rate coefficients to encourage further work

The Effects of Charge Transfer on the Thermal Equilibrium of Photoionized Nebulae

Charge transfer can affect both the ionization and thermal balance of astrophysical plasmas. Using the most recent rate coefficients and energy defects, we calculate the heating/cooling rates for charge transfer reactions between hydrogen and elements up to Z=30. We incorporate these values into the photoionization code CLOUDY. Results from models approximating a wide range of astrophysical objects and conditions suggest that charge transfer can make a significant contribution to the heating near the H ionization front, particularly in objects with a hard ionizing continuum or enhanced abundances. Charge transfer heating can also be important in regimes in which the usual heating/cooling agents are suppressed, such as the emission-line clouds near quasars. We list those reactions that are most important for determining the thermal balance, in the hopes of facilitating improved atomic data

Temperature Fluctuations in Photoionized Nebulae

Recombination lines in gaseous nebulae frequently yield parent-ion abundances that are several times larger than abundances derived from forbidden lines. One possible explanation for this discrepancy is the presence of temperature fluctuations. We examine temperature fluctuations in model nebulae by utilizing Peimbert\u27s t2 parameter. We have run large grids of models, varying the stellar temperature and the total hydrogen density. We consider two abundance sets: The first uses typical planetary nebulae abundances, while the second examines the effect of increasing the metals and grains by a factor of 3. We also consider both a constant density distribution and one which varies sinusoidally with radius. We examine the method of deriving t2 observationally, which uses measured [O III] and Balmer temperatures. We find that this derived t2 shows no correlation with the t2 based on the integral definition. We discuss the reasons for this discrepancy, which include nonvalidity of some of the basic assumptions and theoretical and observational difficulties with the Balmer temperature. We find that, in high-metallicity objects especially, noncollisional contributions to [O III] λ4363 can significantly affect the derived temperature. We argue that while temperature fluctuations may result in non-negligible abundance corrections in some objects, they are insufficient to resolve the abundance discrepancy