Estimating the reproduction number, R0, from individual-based models of tree disease spread

Tree populations worldwide are facing an unprecedented threat from a variety of tree diseases and invasive pests. Their spread, exacerbated by increasing globalisation and climate change, has an enormous environmental, economic and social impact. Computational individual-based models are a popular tool for describing and forecasting the spread of tree diseases due to their flexibility and ability to reveal collective behaviours. In this paper we present a versatile individual-based model with a Gaussian infectivity kernel to describe the spread of a generic tree disease through a synthetic treescape. We then explore several methods of calculating the basic reproduction number R0, a characteristic measurement of disease infectivity, defining the expected number of new infections resulting from one newly infected individual throughout their infectious period. It is a useful comparative summary parameter of a disease and can be used to explore the threshold dynamics of epidemics through mathematical models. We demonstrate several methods of estimating R0 through the individual-based model, including contact tracing, inferring the Kermack–McKendrick SIR model parameters using the linear noise approximation, and an analytical approximation. As an illustrative example, we then use the model and each of the methods to calculate estimates of R0 for the ash dieback epidemic in the UK

Near-Death Experiences, Deathbed Visions, and Past-Life Memories: A Convergence in Support of van Lommel's Consciousness Beyond Life

ABSTRACT: This review supports cardiologist Pim van Lommel's continuity claim for human existence in his recently published book Consciousness Beyond Life: The Science of the Near-Death Experience (2010). Van Lommel and colleagues (van Lommel, van Wees, Meyers, & Elfferich, 2001) studied NDEs among 344 Dutch hospital patients who had been resuscitated following cardiac arrest. From their and others' NDE research findings (e.g., accurate perceptions during the arrest period), van Lommel and colleagues concluded that mental activity can take place even in the absence of cerebral function. Extrapolating from this conclusion, van Lommel claimed in Consciousness Beyond Life a fundamental continuity for individual human existence: that death and birth mark not final limits but instead the transition from one state of consciousness to another. In the course of making his continuity claim, van Lommel referred to other topics such as deathbed visions and past-life memories. In addition to reviewing NDE research, this article reviews research and illustrative responses pertaining to these related phenomena. A convergence of corroborative evidence is consistent with van Lommel's continuity claim. KEYWORDS: Near-death experience; deathbed vision; past-life memory; consciousness; non-locality John C. Gibbs, Ph.D., is Professor of Developmental Psychology, Psychology Department, The Ohio State University, 1835 Neil Avenue, Columbus, OH 43210. He thanks Jonathan Gibbs, editor Jan Holden, Melvin Morse, Denis Purcell, Lea Queener, Ken Ring, Mike Sabom, Carol Stover, Carisa Taylor, and JohnAlexis Viereck for helpful comments on a preliminary version of this article. Reprint requests should be addressed to Dr. Gibbs at [email protected]. JOURNAL Of NEAR-DEATH STUDIES Pim van Lommel is a distinguished cardiologist, researcher, author, and lecturer with a particular interest in near-death experiences (NDEs). With colleagues As van Lommel acknowledged, the continuity claim for human existence is "nothing new" (p. 82). The view of humans as having a continuing, non-material essence has found advocates throughout human intellectual and religious history. The third-century neoPlatonist philosopher Plotinus posited that humans have souls that originate from and return to a timeless, unitary realm of light and truth. The continuity claim has also found expression in the works of philosophers, theologians, and mystics such as Baruch Spinoza, Meister Eckhart, Paul Tillich, John Shelby Spong, and Kahlil Gibran. Reincarnation in particular has been thematic to Eastern religions or traditions (Hinduism, Jainism, Tibetan Buddhism), ancient Egypt, most tribal traditions, Christian Gnosticism, Jewish mysticism, Norse mythology, and spiritualist literature such as that of theosophy and New Age. Van Lommel is also not the first to base the continuity claim on research findings in psychology and other disciplines. Transpersonal psychologist Jenny Wade (1998) used NDE and ostensible prenatal memories to suggest that a transcendent source of consciousness "predates physical life at the moment of conception and survives it after death" (p. 249). Radiation oncologist Jeffrey Long (2010) concluded from a large online NDE self-report data base that "death is not an end but a transition" to an afterlife (p. 201). Edward Kelly and colleagues (Kelly, Kelly, Crabtree, Gauld, Grosso, & Greyson, 2007) argued the need for a twenty-first century psychology that can adequately accommodate many currently anomalous phenomena, including NDEs and deathbed visions. Their prototype toward a new psychological paradigm retrieved the insights of two of psychology's founding figures, Frederick W. H. Myers and William James, and en-JOHN C. GIBBS 305 compassed contributions ranging from process theology to quantum physics. Yet something importantly new pertains to van Lommel's NDE research-based articulation of the continuity claim: in two words, The Lancet. The prior publication of his and colleagues The challenge meets understandable opposition. How can van Lommel or anyone justifiably use near-death studies to make claims regarding death and beyond? It has been said that an extraordinary hypothesis requires for its acceptance extraordinary evidence-and the continuity hypothesis would certainly seem to be extraordinary. Has not neuroscience established that mind or consciousness is totally a function of the brain-and hence cannot possibly continue once brain activity has ceased? What evidence could be extraordinary enough to challenge this established materialist view of mind qua brain-let alone support a leap into a claim for the existence of an afterlife? Does not such a claim drag scholars back to pre-scientific days of baseless belief, dogma, and superstition? Yet as I will show, there is extraordinary evidence. And as the evidentiary base broadens, the existential and ontological claim becomes compelling. Although van Lommel (2010) based his continuity claim largely on NDE studies, he referred also to related existential phenomena such as deathbed visions or "nearing-death awareness" as well as past-life memories. Such related phenomena round out the picture and merit more extensive attention than that afforded in van Lommel's book alone. Accordingly, in this article I primarily review not only NDEs but also deathbed visions and past-life memories (cf. E. f. . I will illustrate the experiential "feel" of these phenomena as well as review corroborative and converging evidence