Zirconium, Barium, Lanthanum and Europium Abundances in Open Clusters

We present an analysis of the s-process elements Zr, Ba, and La and the r-process element Eu in a sample of 50 stars in 19 open clusters. Stellar abundances of each element are based on measures of a minimum of two lines per species via both equivalent width and spectrum synthesis techniques. We investigate cluster mean neutron-capture abundance trends as a function of cluster age and location in the Milky Way disk and compare them to results found in other studies in the literature. We find a statistically significant trend of increasing cluster [Ba/Fe] as a function of decreasing cluster age, in agreement with recent findings for other open cluster samples, supporting the increased importance of low-mass asymptotic giant branch stars to the generation of s-process elements. However, the other s-process elements, [La/Fe] and [Zr/Fe], do not show similar dependences, in contrast to theoretical expectations and the limited observational data from other studies. Conversely, cluster [Eu/Fe] ratios show a slight increase with increasing cluster age, although with marginal statistical significance. Ratios of [s/r]-process abundances, [Ba/Eu] and [La/Eu], however, show more clearly the increasing efficiency of s-process relative to r-process enrichment in open cluster chemical evolution, with significant increases among younger clusters. Last, cluster neutron-capture element abundances appear to be independent of Galactocentric distance. We conclude that a homogeneous analysis of a larger sample of open clusters is needed to resolve the apparent discrepant conclusions between different studies regarding s-process element abundance trends with age to better inform models of galactic chemical evolution.Comment: 24 pages, 13 figures, 10 tables; published in The Astronomical Journa

Climate change and health in Earth's future

Threats to health from climate change are increasingly recognized, yet little research into the effects upon health systems is published. However, additional demands on health systems are increasingly documented. Pathways include direct weather impacts, such as amplified heat stress, and altered ecological relationships, including alterations to the distribution and activity of pathogens and vectors. The greatest driver of demand on future health systems from climate change may be the alterations to socioeconomic systems; however, these “tertiary effects” have received less attention in the health literature. Increasing demands on health systems from climate change will impede health system capacity. Changing weather patterns and sea-level rise will reduce food production in many developing countries, thus fostering undernutrition and concomitant disease susceptibility. Associated poverty will impede people’s ability to access and support health systems. Climate change will increase migration, potentially exposing migrants to endemic diseases for which they have limited resistance, transporting diseases and fostering conditions conducive to disease transmission. Specific predictions of timing and locations of migration remain elusive, hampering planning and misaligning needs and infrastructure. Food shortages, migration, falling economic activity, and failing government legitimacy following climate change are also “risk multipliers” for conflict. Injuries to combatants, undernutrition, and increased infectious disease will result. Modern conflict often sees health personnel and infrastructure deliberately targeted and disease surveillance and eradication programs obstructed. Climate change will substantially impede economic growth, reducing health system funding and limiting health system adaptation. Modern medical care may be snatched away from millions who recently obtained it

Social determinants in an Australian urban region: A 'complexity' lens

This item is under embargo for a period of 12 months from the date of publication, in accordance with the publisher's policy. This is a pre-copyedited, author-produced PDF of an article accepted for publication in Health Promotion International following peer review. The version of record [Fisher, M., Milos, D., Baum, F., & Friel, S (2014) Social determinants in an Australian urban region: a ‘complexity’ lens, Health Promotion International] is available online at: doi: 10.1093/heapro/dau071Area-based strategies have been widely employed in efforts to improve population health and take action on social determinants of health (SDH) and health inequities; including in urban areas where many of the social, economic and environmental factors converge to influence health. Increasingly, these factors are recognised as being part of a complex system, where population health outcomes are shaped by multiple, interacting factors operating at different levels of social organisation. This article reports on research to assess the extent to which an alliance of health and human service networks is able to promote action on SDH within an Australian urban region; using a complex systems frame. We found that such an alliance was able to promote some effective action which takes into account complex interactions between social factors affecting health, but also identified significant potential barriers to other forms of desired action identified by alliance members. We found that a complex systems lens was useful in assessing a collaborative intervention to address SDH within an urban region. Key words: Complex systems, urban health, social determinants of health, collaboratio

Desert Spring Prokaryotes and Benthic Macroinvertebrates: Geological and Ecological Controls

Desert springs are aquatic oases, being considered among the most diverse and imperiled ecosystems on Earth. Despite the ecological significance and threatened status of desert springs, few studies have surveyed the microorganisms in these systems or their interactions with other community members. The primary goal of this dissertation was to describe the major controls influencing the community ecology of prokaryotic and BMI communities in cold- and moderate-temperature desert springs of the southern hydrographic Great Basin. Chapter 1 provides a broad overview of spring ecosystems and of each chapter included in this dissertation. Chapter 2 documents the first-ever, regional-scale survey of the desert spring microbiome and describes the differences in diversity, composition, and functional profiles between the major spring recharge groups. This chapter also contains an extended analysis placing the desert spring microbiome within the context of the Earth Microbiome Project database to assess the uniqueness of desert springs as a biome and identify potential prokaryotic crenophiles and/or endemics. Chapters 3 and 4 discuss geological and ecological controls on the community ecology of benthic prokaryotes and BMIs within a detailed ecohydrogeological framework at a local (Chapter 4) and regional (Chapter 3) scale. These chapters also speculate about possible metabolic interactions occurring between these two communities in the spring benthos food web. Further, Chapter 3 presents a conceptual model of desert spring benthic communities characterizing the dominant physicochemical and biological differences between spring recharge groups. Although a deviation from the primary goal of this dissertation, Chapter 5 describes the first cultivation-independent survey of the Atlantic horseshoe crab (Limulus polyphemus) microbiome in wild and captive populations. Chapter 6 briefly summarizes the major conclusions of each chapter and discusses possible directions for future research on spring ecosystems