New biostratigraphic, magnetostratigraphic and isotopic insights into the Middle Eocene Climatic Optimum in low latitudes

The Middle Eocene Climatic Optimum (MECO) was a warming event that interrupted the long-term Eocene cooling trend. While this event is well documented at high southern and mid-latitudes, it is poorly known from low latitudes and its timing and duration are not well constrained because of problems of hiati, microfossil preservation and weak magnetic polarity in key sedimentary sections. Here, we report the results of a study designed to improve the bio-, magneto- and chemostratigraphy of the MECO interval using high-resolution records from two low-latitude sections in the Atlantic Ocean, Ocean Drilling Program (ODP) Sites 1051 and 1260. We present the first detailed benthic foraminiferal stable isotope records of the MECO from the low latitudes as well as the biostratigraphic counts of Orbulinoides beckmanni and new magnetostratigraphic results. Our data demonstrate a ~ 750 kyr-long duration for the MECO characterized by increasing δ13C and decreasing δ18O, with minimum δ18O values lasting ~ 40 kyr at 40.1 Ma coincident with a short-lived negative δ13C excursion. Thereafter, δ18O and δ13C values recover rapidly. The shift to minimum δ18O values at 40.1 Ma is coincident with a marked increase in the abundance of the planktonic foraminifera O. beckmanni, consistent with its inferred warm-water preference. O. beckmanni is an important Eocene biostratigraphic marker, defining planktonic foraminiferal Zone E12 with its lowest and highest occurrences (LO and HOs). Our new records reveal that the LO of O. beckmanni is distinctly diachronous, appearing ~ 500 kyr earlier in the equatorial Atlantic than in the subtropics (40.5 versus 41.0 Ma). We also show that, at both sites, the HO of O. beckmanni at 39.5 Ma is younger than the published calibrations, increasing the duration of Zone E12 by at least 400 kyr. In accordance with the tropical origins of O. beckmanni, this range expansion to higher latitudes may have occurred in response to sea surface warming during the MECO and subsequently disappeared with cooling of surface waters

Symbiont 'bleaching' in planktic foraminifera during the Middle Eocene Climatic Optimum

Many genera of modern planktic foraminifera are adapted to nutrient-poor (oligotrophic) surface waters by hosting photosynthetic symbionts, but it is unknown how they will respond to future changes in ocean temperature and acidity. Here we show that ca. 40 Ma, some fossil photosymbiont-bearing planktic foraminifera were temporarily 'bleached' of their symbionts coincident with transient global warming during the Middle Eocene Climatic Optimum (MECO). At Ocean Drilling Program (ODP) Sites 748 and 1051 (Southern Ocean and mid-latitude North Atlantic, respectively), the typically positive relationship between the size of photosymbiont-bearing planktic foraminifer tests and their carbon isotope ratios (δ13C) was temporarily reduced for ∼100 k.y. during the peak of the MECO. At the same time, the typically photosymbiont-bearing planktic foraminifera Acarinina suffered transient reductions in test size and relative abundance, indicating ecological stress. The coincidence of minimum δ18O values and reduction in test size–δ13C gradients suggests a link between increased sea-surface temperatures and bleaching during the MECO, although changes in pH and nutrient availability may also have played a role. Our findings show that host-photosymbiont interactions are not constant through geological time, with implications for both the evolution of trophic strategies in marine plankton and the reliability of geochemical proxy records generated from symbiont-bearing planktic foraminifera

If Cumulative Risk Assessment Is the Answer, What Is the Question?

Cumulative risk refers to the combined threats from exposure via all relevant routes to multiple stressors including biological, chemical, physical, and psychosocial entities. Cumulative risk assessment is a tool for organizing and analyzing information to examine, characterize, and possibly quantify the combined adverse effects on human health or ecologic resources from multiple environmental stressors. The U.S. Environmental Protection Agency (EPA) has initiated a long-term effort to develop future guidelines for cumulative risk assessment, including publication in 2003 of a framework that describes important features of the process and discusses theoretical issues, technical matters, and key definitions. The framework divides the process of cumulative risk assessment into three interrelated phases: a) planning, scoping, and problem formulation; b) analysis; and c) interpretation and risk characterization. It also discusses the additional complexities introduced by attempts to analyze cumulative risks from multiple stressors and describes some of the theoretical approaches that can be used. The development of guidelines for cumulative risk assessment is an essential element in the transition of the U.S. EPA risk assessment methodology from a narrow focus on a single stressor, end point, source, pathway, and exposure route to a broader, more holistic approach involving analysis of combined effects of cumulative exposure to multiple stressors via all relevant sources, pathways, and routes

Numerical Evidence for the Observation of a Scalar Glueball

We compute from lattice QCD in the valence (quenched) approximation the partial decay widths of the lightest scalar glueball to pairs of pseudoscalar quark-antiquark states. These predictions and values obtained earlier for the scalar glueball's mass are in good agreement with the observed properties of $f_J(1710)$ and inconsistent with all other observed meson resonances.Comment: 12 pages of Latex, 3 PostsScript figures as separate uufil

Salmonella Typhimurium in the Australian egg industry: multidisciplinary approach to addressing the public health challenge and future directions

In Australia, numerous egg related human Salmonella Typhimurium outbreaks have prompted significant interest amongst public health authorities and the egg industry to jointly address this human health concern. Nationwide workshops on Salmonella and eggs were conducted in Australia for egg producers and regulatory authorities. State and National regulators representing Primary Production, Communicable Disease Control, Public Health and Food Safety and Food Standards Australia and New Zealand. All attendees participated in discussions aimed at evaluating current evidence based information, issues related to quality egg production and how to ensure safe eggs in the supply chain, identifying research gaps and practical recommendations. The perceptions from egg producers and regulatory authorities from various states were recorded during the workshops. We presented the issues discussed during the workshops including Salmonella in the farm environment, Salmonella penetration across egg shell, virulence in humans, food/egg handling in the supply chain and intervention strategies. We also discussed the perceptions from egg producers and regulators. Recommendations placed emphasis on future research needs, communication between industry and regulatory authorities and education of food handlers. Communication between regulators and industry is pivotal to control egg borne S. Typhimurium outbreaks and collaborative efforts are required to design effective and appropriate control strategies.Kapil K. Chousalkar, Margaret Sexton, Andrea McWhorter, Kylie Hewson, Glen Martin, Craig Shadbolt & Paul Goldsmit

Towards the glueball spectrum of full QCD

We present first results on masses of the scalar and tensor glueballs as well as of the torelon from simulations of QCD with two light flavours of Wilson fermions. The gauge configurations of extent 16^3*32 at beta = 5.6 and kappa = 0.156, 0.157 and 0.1575 have been generated as part of the SESAM collaboration programme. The present lattice resolutions correspond to 1/a = 2.0-2.3 GeV and ratios m(pi)/m(rho) = 0.83, 0.76 and 0.71, respectively. Studies on larger lattice volumes and closer to the chiral limit are in progress.Comment: 4 pages, LaTeX, espcrc2 and epsf styles required, 4 epsf figures, poster presented by G. Bali at Lattice '9

Iterative evolution of digitate planktonic foraminifera

Digitate shell morphologies have evolved repeatedly in planktonic foraminifera throughout the Cretaceous and Cenozoic. Digitate species are usually rare in fossil and modern assemblages but show increased abundance and diversity at times during the Cretaceous and mid- dle Eocene. In this paper we discuss the morphology and stratigraphic distribution of digitate planktonic foraminifera and establish the isotopic depth ecology of fossil ones to draw parallels with modern counterparts

Adaptive Step Size for Hybrid Monte Carlo Algorithm

We implement an adaptive step size method for the Hybrid Monte Carlo a lgorithm. The adaptive step size is given by solving a symmetric error equation. An integr ator with such an adaptive step size is reversible. Although we observe appreciable variations of the step size, the overhead of the method exceeds its benefits. We propose an explanation for this phenomenon.Comment: 13 pages, 5 Postscript figures, late

Psychometric Characteristics of the Connor-Davidson Resilience Scale (CD-RISC) in Postpartum Mothers with Histories of Childhood Maltreatment

Background: There is increased awareness that resilience serves as a protective factor against adverse psychophysiological sequelae in the context of stress. However, there are few instruments to assess this construct in adult populations. The Connor-Davidson resilience scale (CD-RISC) has been developed to assess adaptation following stress exposure. While this instrument has previously demonstrated impressive reliability and construct validity, prior research has not supported the consistency of the originally described factor structure. There is also limited evidence regarding the measurement of resilience in the context of cumulative stress exposure. Objectives: This research explores the psychometric properties of the CD-RISC in mothers with childhood histories of maltreatment Materials and Methods: Postpartum women who endorsed a history of childhood abuse or neglect (N = 141) completed the CD-RISC, the childhood trauma questionnaire and other surveys measuring positive and negative health and functioning. We calculated descriptive statistics with percentage counts and means as appropriate. Internal reliability was evaluated by Cronbach’s alpha and the calculation of item-to-total score correlations. Parallel analysis (PA) was utilized to derive the number of retained factors. Results: A recent parenting transition concomitant with a history of maltreatment was associated with lower CD-RISC scores. Internal reliability and concurrent validity analyses were satisfactory and consistent with predicted hypotheses. Exploratory factor analysis (EFA) supported a four-factor model of resilience with this population. Conclusions: This research offers further evidence of the reliability and validity of the CD-RISC. Further, the results of the EFA with parallel analysis offer an empirically-driven derivation of factors for this population