Simulation model of a predator-prey system comprised ofPhytoseiulus persimilis andTetranychus urticae. II. Model sensitivity to variations in the life history parameters of both species and to variations in the functional response and components of the numerical response

Summary A detailed sensitivity analysis of a model of a predator-prey system comprised ofTetranychus urticae andPhytoseiulus persimilis was performed. The aim was to assess the relative importance of the life history parameters of both species, the functional response, and the components of the numerical response. In addition, the impact of the initial predator-prey ratio and the timing of predator introduction were tested. Results indicated that the most important factors in the system were relative rates of predator and prey development, the time of onset of predator oviposition, and the mode of the predator's oviposition curve. The total oviposition of the predator, the effect of prey consumption on predator oviposition, and predator searching were important under some conditions. Factors of moderate importance were the adult female predator's functional response, total prey oviposition, the mode of the prey's oviposition curve, abiotic mortality of the pre-adult predator, and the effect of prey consumption on predator development and on the immature predator's mortality. Factors of least importance were the variances of the predator's and prey's oviposition curves, the abiotic mortality of the adult predator, the abiotic mortality of the pre-adult and adult prey, the functional response of the nymphal and adult male predators, and the effect of prey consumption on adult predator mortality. The sex ratios had little effect, except when the proportion of female predators was very low. The initial predator-prey ratio and time of predator introduction had significant impacts on system behavior, though the patterns of impact were different.     

Modelling the management of underground water assets

Central to the activities of any industry is the modernization of its assets. This paper describes the application of statistical methods to the asset management plan of a large water company. A model for the underground assets is given in detail, and the extensive computations required are illustrated. A Bayesian model shows the consequences of various policy options and provides realistic measures of the uncertainty connected with them.     

Singapore's Malay-Muslim minority: Social identification in a post-‘9/11’ world

Fundamental within Singapore's modernisation push ‘From Third World to First’ was the long-term strategy of establishing a Singapore identity based on multiracialism, multilingualism, multiculturalism and multireligiousity (the ‘4Ms’). But while wholesale landscape changes have largely removed earlier associations between ethnicity and residence, government promotion of a shared Singapore identity has been frustrated by the lagging educational and socio-economic achievements of Singapore's Malay minority. Prior to the events of ‘9/11’ government concern had centred on the growing popularity of private Islamic schools, or madrasahs, which in the government's view could affect educational standards in the city-state. However, following the destruction of the World Trade Center government attention was quickly shifted to the promotion of ‘racial harmony’ and Singaporeans were urged to ‘get to know your neighbours’ in a tacit admission that 40 years of ‘racial’ assimilation had yet to produce ethnically integrated, cross-cultural community spirit. Subsequent events, particularly the arrest of local Jemaah Islamiyah operatives and the destruction in Iraq, have impacted most strongly upon Singapore's Malay-Muslim community and posed challenges to its identity within a multicultural society.     

Maternal Functioning, Time, and Money: The World of Work and Welfare

Numerous studies have assessed families' employment and financial stability following welfare reform. Yet little research has addressed whether welfare and work transitions are linked with other changes in family functioning. Using a representative sample of approximately 2,000 low-income urban families from the Three-City Study, analyses assessed whether mothers' welfare and employment experiences over a two-year period following welfare reform were related to changes in family well-being. Lagged regression models controlling for family characteristics and earlier levels of functioning found that moving into employment and stable employment (of 30 hours or more per week) were linked to substantial increases in income and improvements in mothers' psychological well-being. Movements into employment also were associated with declines in financial strain and food insecurity. Sustained or initiated welfare receipt was related to relative declines in income, physical health, and psychological well-being, but also to improved access to medical care. In contrast, mothers' welfare and work experiences showed very limited relations to changes in the quality of parenting or of children's home environments. These patterns were similar for families with young children and those with adolescent children. Results suggest that parenting behaviors are more resistant to change than are maternal emotional and economic functioning.     

Social mobility in Scotland since the middle of the twentieth century

Extensive mobility between class of origin and class of destination has been a characteristic feature of societies in Europe and North America since the middle of the twentieth century. Most mobility has been upward, and most of that has been explicable by occupational change – by the rise in the proportion of the labour force which works in service‐class jobs and the decline in the proportion in manual jobs. This pattern may now be changing, because parents of younger cohorts (people born since the 1960s) have themselves benefited from upward mobility and so there is less scope for further upward movement by their offspring. The paper uses a large new data source for Scotland to investigate these topics. It finds that there is still a great deal of mobility, and that, although upward mobility still predominates, its amount is lower in younger cohorts than in older. Nevertheless, relative mobility has not changed as upward mobility has declined, just as in earlier studies it was found not to have changed as upward mobility rose. These patterns are similar for men and women.     

Social Policy in South Korea: Cultural and Structural Factors in the Emergence of Welfare

There are a number of features that make South Korea an interesting place to study social policy. First, it has experienced rapid economic development with the associated changes in urbanization and demography. This change has created social problems, which the state has had to address. Second, the country retains a strong cultural tradition and repeated affirmation of the values and practices of Confucianism. In this paper, these two features are considered in relation to the way social policy has been addressed. The thrust of the paper will be on the policy responses to perceived social problems and the way in which other social problems are individualized within families. These policies are informed and shaped by Korean politics and culture.     

Effects of alcohol on the nonverbal communication of anxiety: The impact of beliefs on nonverbal behavior

Three male and three female raters were shown videotapes of 29 male subjects who were speaking to a silent female confederate. Raters were asked to make 10 judgments about the subjects' behavior. The subjects had been assigned to one of two expectancy conditions in which they were led to believe the drink they consumed prior to meeting the confederate contained alcohol and tonic or tonic only. Actually, half of the subjects in each expectancy condition received alcohol and half received tonic only. Judgments of the female raters viewing the videotapes were congruent with physiological measures of the subjects' anxiety. Those subjects who believed they received alcohol were perceived by female raters as more relaxed, less anxious, less inhibited, and more dominant than subjects who believed they received tonic. The actual content of the drink had no significant effects on the raters' judgements of the subjects' behavior. Male raters were unable to discriminate among the experimental conditions. Implications for possible gender of rater effects in behavioral assessment procedures as well as for the impact of beliefs on nonverbal communication are discussed.     

Skills,control, and the mass professions

Since members of the mass professions are employed mainly by large organisations in the public sector, they are increasingly ‘managed’. What is happening to their skills, their control over their own work, and their professionalism, are matters of concern as revealed by recent disputes. These are precisely questions at the heart of the labour process debate relaunched by Braverman. The insights generated by this stream of writing, already profitably applied beyond blue collar work to clerical occupations may be extended to embrace elements of the service class. There the notion of indetermination goes beyond the notion of discretion. Changes in public ideology have effects analogous to those arising from technological innovation in manufacturing. Yet professionals, whilst attending to technological aspects of their work, typically ignore the wider social issues. In this respect they are vulnerable to deskilling and erosion of control over their work.     

PARTY POLITICS AND THE PRICE OF PAYOLA

The literature contains two competing views of the role of political parties: parties are treated either as associations of interest groups supported to the degree that they offer electoral support in the lawmaker's district, or as expressions of the personal ideologies of the lawmakers. In this paper parties are treated as bargaining agents for groups of lawmakers in their dealings with interest groups. Interest groups are depicted buying votes on proposals where those votes are cheapest. Parties are combinations of consistently low-price vote suppliers. The theory has empirical power that discriminates between it and the two competing models.