An Approach for Modeling Noncancer Dose Responses with an Emphasis on Uncertainty

This paper presents an approach for characterizing the probability of adverse effects occurring in a population exposed to dose rates in excess of the Reference Dose (RfD). The approach uses a linear threshold (hockey stick) model of response and is based on the current system of uncertainty factors used in setting RfDs. The approach requires generally available toxicological estimates such as No-Observed-Adverse-Effect Levels (NOAELs) or Benchmark Doses and doses at which adverse effects are observed in 50% of the test animals (ED₅₀s). In this approach, Monte Carlo analysis is used to characterize the uncertainty in the dose response slope based on the range and magnitude of the key sources of uncertainty in setting protective doses. The method does not require information on the shape of the dose response curve for specific chemicals, but is amenable to the inclusion of such data. The approach is applied to four compounds to produce estimates of response rates for dose rates greater than the RfD     

Population,swidden farming and the tropical environment

Swidden farming has been blamed for the degradation of tropical forest, where it is widely used. However, when the cropping period is short and the fallow period long, the system is shown to be ideally suited to this environment. But this entails a low population density. When this is exceeded, the fallow must be shortened, resulting in loss of forest through grassland invasion, or of the soil itself through erosion or laterization, as shown by modern examples and by the history of the Maya. The degradation blamed on swidden farming is thus not due to the system itself, but to overpopulation, in H.G. Wells's words, "the fundamental evil out of which all the others that afflicted the race arose."This paper is a shortened and updated version of a lecture given in the Department of Biological Anthropology, University of Oxford, on 6 November 1986.     

The therapist who is perceived as "spiritually correct": strategies for avoiding collusion with the "spiritually one-up" spouse

Marital and family therapists who are perceived by the community as having a strong spiritual orientation face unique and difficult challenges. Clients who seek their help often bring a mix of expectations that can create a situation in which the therapist may struggle with multiple roles, some not of his or her choosing. These expectations are especially challenging when one spouse views him-or herself as "spiritually one-up" and wants the therapist to form a spiritually based coalition against the other partner. This paper describes the various dilemmas that therapists may face when clients perceive them as having spiritual expertise and presents strategies that can be used for avoiding these dilemmas. A case study illustrates the use of these approaches.     

Environmental scanning for Social Services

This article describes the development of a process of systematic regional environmental scanning as part of strategic planning in the Ministry of Social Services (MSS) in British Columbia, over the 1987-1990 period. Social Services, a large regionalized social service organization, adopted a formal strategic planning process in early 1988. Ministry services are delivered in ten regions with widely varying characteristics. To ensure that this diversity is reflected in the planning process, it is essential that regional environmental information receive consideration. A simple format was developed and regional directors asked to consult with their staff and to scan their regions for issues that may impact the ministry over the medium term. The information obtained was presented by regional directors at a Senior Management Committee meeting and included in the ministry's annual Business Plan, a document which informs staff, contractors, stakeholders, and the community at large of the ministry's values, objectives, and operational goals. The inclusion of regional analyses adds useful information to the Plan. A second output of the planning process is the ministry budget. The systematic regional scans were found to be extremely useful to regional staff, other directors, and to the ministry executives while setting priorities.     

The systems revolution

In this paper the author brings together a number of ideas which are presented more fully in his forthcoming book—Redesigning the Future (John Wiley and Sons, New York): This synthesis amounts to a digest of Part 1 of that book. The article is organized into 5 parts: The Systems Revolution; The Self-Control Problem; The Humanization Problem; The Environmentalization Problem and Science in the Systems Age.     

Wheelchair coasting downhill is a reliable work task

OBJECTIVE: To measure test-retest reliability of physiological responses during submaximal wheelchair downhill and horizontal treadmill ergometry. DESIGN: A test-retest design was used on a convenience sample. Four male and three female non-wheelchair users, (22-43 years of age) propelled or coasted in a wheelchair under steady-state conditions. Four minute work bouts were performed at 1, 2, 3, and 4 km/hr. (0.62, 1.24, 1.86 and 2.5 mph, respectively) at 0 degrees, -2 degrees, and -4 degrees. Subjects were studied twice under each of the 12 conditions. Six tests were performed daily, with testing occurring over four days. Dependent variables included oxygen consumption, minute ventilation and heart. Intraclass correlation coefficients were determined for each set of paired tests. RESULTS: Intraclass correlation coefficients were high for absolute VO_{2}(R=0.84-0.99), V_{E} (R=0.86-0.98) and HR (R=0.95-1.0) over the range of 4 speeds and 3 inclinations studied. On average, % differences from test 1 to test 2 were less than 3%. CONCLUSION: At the treadmill speeds and inclinations (positive and negative) studied in this investigation, untrained wheelchair users responded in a physiologically reliable manner.     

An investigation into causal links between victimization and offending in adolescents

There is a considerable body of evidence from earlier research to show that offending is associated with an increased risk of victimization, and being a victim with an increased risk of offending. There have been few earlier studies of the link. These have generally set out to test specific explanations, for example, the idea that the same lifestyles or routine activities may be associated with both victimization and offending. In a current study of a cohort of 4,300 adolescents in Edinburgh we have found a correlation of 0.421 between crime victimization and self-reported offending at the age of 15 when offending peaks. Variables chosen to test three broad types of theory - life-style and routine activities, weak social bonds, aspects of personality - are shown to be related both to victimization and to offending in adolescence. The present analysis uses latent class growth mixture models to track the dynamic relationships over time between adolescent victimization and offending both before and after controlling for these explanatory variables. In the short term, offending is strongly related to a later rise in victimization, but in the longer term to a fall that tends to cancel out the earlier rise. These findings remain the same after controlling for the ten explanatory variables. Victimization is associated with a later rise in offending in the longer term. The theoretical perspectives suggested by earlier researchers are fairly successful in explaining this linkage running from victimization to offending. Future research should focus on the role of peer influence in linking victimization and offending, and should push forward the analysis into the adult years. The implications for criminal justice policy could be far-reaching.     

The Factors Influencing Saving in a Matched Savings Program: Goals,Knowledge of Payment Instruments,and Other Behavior

This paper explores the saving behavior of the group of low-income households that have participated in the Australian Saver Plus matched savings program. The paper finds that a dynamic panel model represents a good technique for modeling the savings account balances of such participants. We find that, even after controlling for the unobservable individual response to the program incentive, the saving goal and education/financial literacy variables play a positive role in encouraging saving behavior. More importantly however, we find that programs such as Saver Plus are able to modify the saving behavior of individuals to the point where their prior behavior and their inherent attitude towards saving no longer play a significant role.