Estimation of the mutagenic potency of environmental chemicals using short-term bioassay

The Ames Salmonella test is a widely used bioassay method for assessing the mutagenic potency of a potential carcinogen. The test is quick and reliable, and exploits the correlation that exists between mutagenic potential and carcinogenic potential. The data for this case study came from an international study involving 20 laboratories in nine countries. The laboratories participated in a designed experiment in which substances (complex chemical mixtures of the type encountered in the environment) were evaluated for mutagenicity using the Ames test. A stringent protocol was followed. The study's principal aim was to investigate intra- and inter-laboratory variation in test results. The data consist of counts of revertant Salmonella colonies at each of six dose levels of a substance. The data were obtained for each of five test substances from each participating laboratory. The bioassays were carried out according to a prescribed factorial experimental design. Three sets of analysts participated in this case study. They were asked to model the dose-response relationship for two substances, to develop an index of the strength of the relationship, and to assess intra- and inter-laboratory variation in bioassay results.     

Extreme-value analysis of canadian wind speeds

Estimates of extreme winds are essential for engineering design, but in preparing such estimates major statistical issues are encountered. In this case study, the analysts were provided with hourly readings on wind speed, wind direction, and barometric pressure at five Canadian stations for observation periods ranging over several recent decades. Their assignment was to calculate point and interval estimates of 10-, 20-, 50-, and 100-year return values (i.e., upper fractiles) for the wind speeds at these stations.     

Total Performance Inconsistency and Status Generalization: An Expectation States Formulation*

Past research has documented the fact that status characteristics organize group interaction. Freese and Cohen (1973) specified a condition under which a performance characteristic would eliminate the effect of a differentiating diffuse status characteristic. The present research extends the Freese-Cohen theory to specify a condition under which a differentiating diffuse status characteristic will eliminate the effect of a performance characteristic. Predictions derived from the formulation are (a) in situations where actors are differentiated by a diffuse status characteristic and a totally inconsistent performance characteristic, influence rates will be a function only of diffuse status and (b) it is the strength (0) of a totally inconsistent performance characteristic, rather than the number of traits comprising the characteristic, that determines its effect. These predictions are contrasted with those of other expectation states formulations (i.e., Berger et al., 1977). Laboratory experiments generally support our formulation while providing some disconfirming evidence for the other formulations.     

Prediction and Prevention of Child Abuse and Neglect

A high-risk population was successfully identified by the use of perinatal screening procedures. These children encountered significantly different parenting practices than the low-risk "control" group. There were also significant differences between "High-Risk" and "Low-Risk" families on issues concerning social adjustment and mother/infant attachment. Five children in a "High-Risk Nonintervene" group required hospitalization for serious injuries thought to be secondary to abnormal parenting practices. There were no such hospitalizations in either a High Risk Intervene group or a Low Risk group. Labordelivery observations, and postpartum interviews and observations provided the most accurate predictive information; prenatal interviews and questionnaires did not add significantly. Perinatal assessment and simple intervention with families at high risk for abnormal parenting practices significantly improves the infants' chances for escaping serious hospitalized physical injury.     

Successful joint ventures in Science Parks

Technology-based firms are looking for ways of minimizing the increasing risks and costs of developing new products and processes. Acquisition of new technology through a collaborative development is one way which is finding favour. Universities, their associated Science Parks and spinout companies offer opportunities for such partnerships which are growing in importance. The services available by this route to large companies are attracting a substantial international clientele.