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/ .     

Existence and Uniqueness of Q-Processes with a Given Finite μ-Invariant Measure

Let Q be a stable and conservative Q‐matrix over a countable state space S consisting of an irreducible class C and a single absorbing state 0 that is accessible from C. Suppose that Q admits a finite μ‐subinvariant measure m on C. We derive necessary and sufficient conditions for there to exist a Q‐process for which m is μ‐invariant on C, as well as a necessary condition for the uniqueness of such a process.     

Postmodern synergistic knowledge creation: extending the boundaries of disability studies

The tensions between the competing discourses of the medical and the social models of disability have traditionally provided a platform for discussion and research in the fields of disability studies and special needs education. Over the last 30 years a wealth of literature has consolidated the debate and produced particular knowledge of impairment and disability. In this paper we argue that by privileging notions of ‘deficit’ within these medical or social model perspectives the richness of the lived experience of people with impairments is denied. The individual becomes lost within a framework of medical symptoms or social inequalities. This paper considers alternative approaches which reveal a fuller picture of the lives of people with impairments. The authors conducted two separate empirical studies, one employing a Deleuzo‐Guattarian perspective, the other a Bourdieusian perspective. In this paper we illustrate how these theories of practice can reveal situated understandings of the individual with impairments and his/her daily life. By embracing new understandings and different theoretical perspectives we show how new knowledge can emerge to illuminate the fluid and ever‐changing notions of ‘disability’, ‘inclusion’ and ‘exclusion’, which form elements of the individual lived experience of the research participants.     

Disentangling the exposure experience: the roles of community context and report-back of environmental exposure data

This article examines participants' responses to receiving their results in a study of household exposure to endocrine disrupting compounds and other pollutants. The authors study how the "exposure experience"-the embodied, personal experience and understanding of chronic exposure to environmental pollutants-is shaped by community context and the report-back process itself. In addition, the authors investigate an activist, collective form of exposure experience. The authors analyze themes of expectations and learning, trust, and action. The findings reveal that while participants interpret scientific results to affirm lay knowledge of urban industrial toxics, they also absorb new information regarding other pollutant sources. By linking the public understanding of science literature to the illness and exposure experience concepts, this study unravels the complex relationship between lay experience and lay understanding of science. It also shows that to support policy development and/or social change, community-based participatory research efforts must attend to participants' understanding of science.     

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...