Fitting and comparing seed germination models with a focus on the inverse normal distribution

This paper reviews current methods for fitting a range of models to censored seed germination data and recommends adoption of a probability‐based model for the time to germination. It shows that, provided the probability of a seed eventually germinating is not on the boundary, maximum likelihood estimates, their standard errors and the resultant deviances are identical whether only those seeds which have germinated are used or all seeds (including seeds ungerminated at the end of the experiment). The paper recommends analysis of deviance when exploring whether replicate data are consistent with a hypothesis that the underlying distributions are identical, and when assessing whether data from different treatments have underlying distributions with common parameters. The inverse normal distribution, otherwise known as the inverse Gaussian distribution, is discussed, as a natural distribution for the time to germination (including a parameter to measure the lag time to germination). The paper explores some of the properties of this distribution, evaluates the standard errors of the maximum likelihood estimates of the parameters and suggests an accurate approximation to the cumulative distribution function and the median time to germination. Additional material is on the web, at http://www.agric.usyd.edu.au/staff/oneill/ .     

Outcasts…Outliers…Oppressed: Civic Advocates in U.S. History Worth Investigating

As de Tocqueville recognized, the U.S. democratic system relies on the advocacy of civic-minded individuals. Although U.S. history is replete with persons using different means to advance one or more democratic principles, VanSledright and Hess argued that secondary history education reinforces a persistent national narrative, one characterized by progress toward achieving national goals, an emphasis on ethnic success stories and avoidance of ethnic struggles and conflicts, and a quest for freedom. Such an approach results in a celebratory story of success, rarely one of struggle or failure. This approach silences those seemingly on the fringes of democratic society, denying students access to a richer, more nuanced narrative and to diverse ways to become civically engaged. To address this situation, we suggest first enabling students to contemplate what influences how individuals become civically engaged, next to apply their thinking to contemporary public policy matters, and finally to compare their decisions to those of historical figures, such as Bayard Rustin, often overlooked in the national narrative.     

The Epistemic Integrity of NASA Practices in the Space Shuttle Program

This article presents an account of epistemic integrity and uses it to demonstrate that the epistemic integrity of different kinds of practices in NASA's Space Shuttle Program was limited. We focus on the following kinds of practices: (1) research by working engineers, (2) review by middle-level managers, and (3) communication with the public. We argue that the epistemic integrity of these practices was undermined by production pressure at NASA, i.e., the pressure to launch an unreasonable amount of flights per year. Finally, our findings are used to develop some potential strategies to protect epistemic integrity in aerospace science.     

Net migration and migration effectiveness: A comparison between Australia and the United Kingdom, 1976–96 Part 1: Total migration patterns

A nation’s population is redistributed through migration flows and counterflows between its constituent subnational areas, resulting in a geographical pattern of net migration gains or losses which may change from one time period to another. Migration effectiveness is the indicator commonly used to measure net migration as a proportion of gross migration turnover for any territorial unit. This paper explores the effect of net migration in two different countries, Australia and the United Kingdom, using measures of migration effectiveness computed from period-age migration data sets for a system of city regions assembled for four consecutive five-year periods in each country. While the evidence suggests that the overall effectiveness of net migration has declined over the 20-year period in both countries, marked similarities and contrasts are apparent in the spatial patterning of migration that together provide useful analytical insights into the changing space economies of the two countries.     

The wisdom of family therapists

This qualitative research study explored the ways in which family therapists (MSWs) perceive the family treatment process. A purposive sample of eight practicing clinical social workers were selected for face to face interviews which explored the workers' perceptions of the family treatment process. Findings revealed that although certain consistent themes appear to exist among family therapists, family therapy practice may well be much more idiosyncratic than commonly believed.     

Investigating the impact of Hurricane Maria on an ongoing birth cohort in Puerto Rico

Population and Environment - Prior to Hurricane Maria, Puerto Rico already had 200+ hazardous waste sites, significant contamination of water resources, and among the highest rates of preterm birth...     

A Systems Approach to the Policy‐Level Risk Assessment of Exotic Animal Diseases: Network Model and Application to Classical Swine Fever

Exotic animal diseases (EADs) are characterized by their capacity to spread global distances, causing impacts on animal health and welfare with significant economic consequences. We offer a critique of current import risk analysis approaches employed in the EAD field, focusing on their capacity to assess complex systems at a policy level. To address the shortcomings identified, we propose a novel method providing a systematic analysis of the likelihood of a disease incursion, developed by reference to the multibarrier system employed for the United Kingdom. We apply the network model to a policy‐level risk assessment of classical swine fever (CSF), a notifiable animal disease caused by the CSF virus. In doing so, we document and discuss a sequence of analyses that describe system vulnerabilities and reveal the critical control points (CCPs) for intervention, reducing the likelihood of U.K. pig herds being exposed to the CSF virus.