The Parasitoid Complex of Forest Tent Caterpillar, \u3ci\u3eMalacosoma Disstria\u3c/i\u3e (Lepidoptera: Lasiocampidae), in Eastern Wyoming Shelterbelts

A parasitoid complex affecting the forest tent caterpillar, Malacosoma disstria, was investigated during 1978-79 in shelterbelts in eastern Wyoming. Egg parasitoids included five species: Ablerus clisiocampae, Ooencyrtus clisiocampae, Telenomus clisiocampae, Tetrastichus sp. 1 and Telenomus sp. Thirteen hymenopterous species and five dipterous species were reared from larvae and pupae of the forest tent caterpillar. The most common 5th-instar larval parasitoids were the tachinid flies, Lespesia archippivora and Archytas lateralis. Of the pupal parasitoids reared, 640/0 were Diptera and 36% were Hymenoptera. Four previously unrecorded parasitoids of M. disstria were reared: Cotesia alalantae, Macrocentrus irridescens, Pimpla sanguinipes erythropus, and Lespesia flavifrons.

Linear and fractal diffusion coefficients in a family of one dimensional chaotic maps

We analyse deterministic diffusion in a simple, one-dimensional setting consisting of a family of four parameter dependent, chaotic maps defined over the real line. When iterated under these maps, a probability density function spreads out and one can define a diffusion coefficient. We look at how the diffusion coefficient varies across the family of maps and under parameter variation. Using a technique by which Taylor-Green-Kubo formulae are evaluated in terms of generalised Takagi functions, we derive exact, fully analytical expressions for the diffusion coefficients. Typically, for simple maps these quantities are fractal functions of control parameters. However, our family of four maps exhibits both fractal and linear behavior. We explain these different structures by looking at the topology of the Markov partitions and the ergodic properties of the maps.Comment: 21 pages, 19 figure

Well-being poverty versus income poverty and capabilities poverty?

The conventional approach of economists to the measurement of poverty in poor countries is to use measures of income or consumption. This has been challenged by those who favour broader criteria for poverty and its avoidance. These include the fulfilment of .basic needs., the .capabilities. to be and to do things of intrinsic worth, and safety from insecurity and vulnerability. This paper asks: to what extent are these different concepts measurable, to what extent are they competing and to what extent complementary, and is it possible for them to be accommodated within an encompassing framework? There are two remarkable gaps in the rapidly growing literature on subjective well-being. First, reflecting the availability of data, there is little research on poor countries. Second, within any country, there is little research on the relationship between well-being and the notion of poverty. This paper attempts to fill these gaps. Any attempt to define poverty involves a value judgement as to what constitutes a good quality of life or a bad one. We argue that an approach which examines the individual.s own perception of well-being is less imperfect, or more quantifiable, or both, as a guide to forming that value judgement than are the other potential approaches. We develop a methodology for using subjective well-being as the criterion for poverty, and illustrate its use by reference to a South African data set containing much socio-economic information on the individual, the household and the community, as well as information on reported well-being. We conclude that it is possible to view subjective well-being as an encompassing concept, which permits us to quantify the relevance and importance of the other approaches and of their component variables. The estimated well-being functions for South Africa contain some variables corresponding to the income approach, some to the basic needs (or physical functioning) approach, some to the relative (or social functioning) approach, and some to the security approach. Thus, our methodology effectively provides weights of the relative importance of these various components of well-being poverty.

Temporal-varying failures of nodes in networks

We consider networks in which random walkers are removed because of the failure of specific nodes. We interpret the rate of loss as a measure of the importance of nodes, a notion we denote as failure-centrality. We show that the degree of the node is not sufficient to determine this measure and that, in a first approximation, the shortest loops through the node have to be taken into account. We propose approximations of the failure-centrality which are valid for temporal-varying failures and we dwell on the possibility of externally changing the relative importance of nodes in a given network, by exploiting the interference between the loops of a node and the cycles of the temporal pattern of failures. In the limit of long failure cycles we show analytically that the escape in a node is larger than the one estimated from a stochastic failure with the same failure probability. We test our general formalism in two real-world networks (air-transportation and e-mail users) and show how communities lead to deviations from predictions for failures in hubs.Comment: 7 pages, 3 figure

Adaption of structured analysis design techniques methodology for construction project planning

The construction industry has been heavily criticised by researchers and governmental organisations for its performance especially excessive delay. Ballard and Howell (2003) indicated that only about 50% of the tasks on weekly work plans are completed by the end of the plan week. This is a result of a lack of either effective project planning or effective production control. It therefore seems the traditional approach of planning is insufficient to meet the current demand and complexity of construction projects. This paper proposes to critically evaluate the adaptation of Structured Analysis Design Techniques (SADT) methodology as a tool for project planning. SADT which was further developed into IDEF (Integrated Definition) techniques claims to be a complete methodology to provide the means of understanding complex production systems and aid the implementation of change. The use of this methodology has led to process improvement. The research uses a literature review followed by interviews with academics and practitioners to investigate their knowledge and understanding of SADT (IDEFO). The results of the interviews indicated that SADT (IDEFO) methodology is seldom known and used in the construction industry. However, this study indicates that SADT methodology appears to be an effective project planning tool. This study contributes to the limited project planning techniques in construction industry by exploring the possible adaption of SADT

Community, Comparisons and Subjective Well-being in a Divided Society

Using a South African data set, the paper poses six questions about the determinants of subjective well-being. Much of the paper is concerned with the role of relative concepts. We find that comparator income - measured as average income of others in the local residential cluster - enters the household’s utility function positively but that income of more distant others (others in the district or province) enters negatively. The ordered probit equations indicate that, as well as comparator groups based on spatial proximity, race-based comparator groups are important in the racially divided South African society. It is also found that relative income is more important to happiness at higher levels of absolute income. Potential explanations of these results, and their implications, are considered. Keywords: Subjective well-being; happiness; comparator groups; altruism; envy; relative deprivation; standard-setting; race; South Africa.

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.

The lone parent pilots after 12 to 24 months: an impact assessment of in-work credit, work search premium, extended schools childcare, quarterly work focused interviews and new deal plus for lone parents

From April 2004, a set of Government policies designed to help lone parents into work have been piloted in various combinations in a number of Jobcentre Plus districts in Great Britain. The five policies are: In Work Credit (IWC), Work Search Premium (WSP), Extended Schools Childcare (ESC) and Childcare Tasters, Quarterly Work Focused Interviews (QWFIs) for lone parents whose youngest child is aged 12 or over in Local Education Authorities (LEAs) in which an ESC pilot is operating (ESQWFI), and New Deal Plus for Lone Parents (ND+fLP), hereafter collectively referred to as 'the lone parent pilots' (LPPs or 'the pilots'). The pilots were rolled out in four Phases, the first three of which are analysed in this report. This report estimates the impact of the LPPs on lone parents who have received Income Support (IS) or Jobseeker's Allowance (JSA) for at least 12 months. It uses a difference-in-differences (DiD) estimator, and makes use of lone parents in districts not operating a pilot as a comparison group. The data covers the first 12 months (Phase 3 districts) to the first 24 months (Phase 1 districts) of the pilots' operation, and so should be seen as giving the early impacts. Impacts were estimated separately for the stock of lone parents who had been on benefit for at least 12 months when the pilots began, and the flow sample of lone parents whose claim of IS/JSA reached 12 months after the pilots began

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.