Risk Management in a Polio-Free World

Inherent in the decision to launch the Global Polio Eradication Initiative in 1988 was the expectation for many people that immunization against poliomyelitis would eventually simply stop, as had been the case with smallpox following its eradication in 1977. However, the strategies for managing the risks associated with a "polio-free" world must be continuously refined to reflect new developments, particularly in our understanding of the live polioviruses in the oral poliovirus vaccine (OPV) and in the international approach to managing potential biohazards. The most important of these developments has been the confirmation in 2000 that vaccine-derived polioviruses (VDPVs) can circulate and cause polio outbreaks, making the use of OPV after interruption of wild poliovirus transmission incompatible with a polio-free world. A comprehensive strategy has been developed to minimize the risks associated with eventual OPV cessation, centered on appropriate long-term biocontainment of poliovirus stocks (whether for vaccine production, diagnosis, or research), the controlled reintroduction of any live poliovirus vaccine (i.e., from an OPV stockpile), and appropriate use of the inactivated poliovirus vaccine (IPV). Although some aspects of this risk management strategy are still debated, there is wide agreement that no strategy would entirely eliminate the potential risks to a polio-free world. The current strategy for risk management in a polio-free world will continue to evolve with better characterization of these risks and the development of more effective approaches both to reduce those risks and to limit their consequences should they occur.     

Return and Onwards Migration in Canada and Australia: Evidence From Fixed Interval Data

Analysis of return and onwards migration flows has typically relied upon lifetime migration definitions. Both Canada and Australia have collected data on usual place of residence both one and five years prior to the census, which provide a richer source of information on return and onwards moves. Utilizing data drawn from complementary sources, this article examines the incidence, composition and spatial patterning of return and onwards migration at the state and provincial level in Canada and Australia over the period of 1986–1990–1991. Results indicate a high degree of symmetry in these processes between the two countries. While many of the findings are consistent with those derived from analysis of lifetime data, we find that one quarter to one third of return moves were to the original (1986) dwelling, indicating a planned return rather than the failed migration as previous literature has often assumed.     

Comparison of the EU T25 Single Point Estimate Method with Benchmark Dose Response Modeling for Estimating Potency of Carcinogens

The T25 single-point estimate method of evaluating the carcinogenic potency of a chemical, which is currently used by the European Union (EU) and is denoted the EU approach, is based on the selection of a single dose in a chronic bioassay with an incidence rate that is significantly higher than the background rate. The T25 is determined from that single point by a linear extrapolation or interpolation to the chronic dose (in mg/kg/day), at which a 25% increase in the incidence of the specified tumor type is expected, corrected for the background rate. Another method used to obtain a carcinogenic potency value based on a 25% increase in incidence above the background rate is the estimation of a T25 derived from a benchmark dose (BMD) response model fit to the chronic bioassay data for the specified tumor type. A comparison was made between these two methods using 276 chronic bioassays conducted by the National Toxicology Program. In each of the 2-year bioassays, a tumor type was selected based on statistical and biological significance, and both EU T25 and BMD T25 estimates were determined for that end point. In addition, simulations were done using underlying cumulative probability distributions to examine the effect of dose spacing, the number of animals per dose group, the possibility of a dose threshold, and variation in the background incidence rates on the EU T25 and BMD estimates. The simulations showed that in the majority of cases the EU T25 method underestimated the true T25 dose and overestimated the carcinogenic potency. The BMD estimate is generally less biased and has less variation about the true T25 value than the EU estimate.     

Open Tertiary Education in Australia

The draft report of the Committee on Open University, Open Tertiary Education, is criticized on the grounds that it is overly conservative and makes little contribution to the opening up of tertiary education in Australia. The problems inherent in government committees, particularly in the field of education, are considered. Using the data provided in the report, the current closed system of tertiary education is criticized and a number of proposals, alternative to those made in the report, are presented for consideration.     

A LOOK AT THE SEMANTIC DIFFERENTIAL AS A TOOL TO ASSIST FACULTY TEACHING EVALUATIONS

The evaluation of the effectiveness of faculty teaching is a difficult process. This paper presents the results of an experimental empirical investigation into the possibility of using a psycho-linguistic measurement technique, the Semantic Differential, to measure faculty communication of terminology to students. This measurement could be used to supplement other teaching evaluation devices. The paper determines a set of “key concepts,” derives a set of S.D. meanings from a Faculty to act as a standard, and measures student meanings at the beginning and end of an introductory course. These sets of meanings are then compared.     

A HEURISTIC ALGORITHM FOR RESOURCE LEVELING IN MULTI-PROJECT,MULTI-RESOURCE SCHEDULING

The utility of conventional project management techniques, such as PERT and CPM, is hampered by significant and realistic network attributes and managerial considerations. There are many situations which involve more than one project and numerous resources. Of major concern in such situations is the reduction of the maximum quantity of each required resource. The algorithm presented here is capable of scheduling the individual activities in multiple projects with multiple resources and leveling the overall quantity of each resource which is required. The basis of the algorithm is a sequencing procedure for examining various combinations of activity start times. The measure of effectiveness for each combination is the sum of the squares of the required quantity of each resource in each time period.     

Conditions leading to collective negotiations among police

The number of cities that negotiate collectively with their police officers has grown rapidly in recent decades, but union penetration has been uneven. This paper tries to identify some of the factors which led to collective negotiations. A model designed to predict formal negotiations is tested using both logit and discriminant analysis. The results indicate that environmental factors and dissatisfaction with working conditions are significant influences on unionization. Far less important is the desire to maintain salaries above market levels. Evidence of state enabling laws contribute little to overall prediction once other factors are considered.     

The role of management attorneys in union organizing campaigns

We examine the role and effect of management attorneys in union organizing campaigns by conducting in-depth interviews with a number of management and union attorneys, union organizers, and NLRB administrators. Hypotheses are developed for future empirical testing.