Eta Carinae and the Luminous Blue Variables

We evaluate the place of Eta Carinae amongst the class of luminous blue variables (LBVs) and show that the LBV phenomenon is not restricted to extremely luminous objects like Eta Car, but extends luminosities as low as log(L/Lsun) = 5.4 - corresponding to initial masses ~25 Msun, and final masses as low as ~10-15 Msun. We present a census of S Doradus variability, and discuss basic LBV properties, their mass-loss behaviour, and whether at maximum light they form pseudo-photospheres. We argue that those objects that exhibit giant Eta Car-type eruptions are most likely related to the more common type of S Doradus variability. Alternative atmospheric models as well as sub-photospheric models for the instability are presented, but the true nature of the LBV phenomenon remains as yet elusive. We end with a discussion on the evolutionary status of LBVs - highlighting recent indications that some LBVs may be in a direct pre-supernova state, in contradiction to the standard paradigm for massive star evolution.Comment: 27 pages, 6 figures, Review Chapter in "Eta Carinae and the supernova imposters" (eds R. Humphreys and K. Davidson) new version submitted to Springe

Neural correlates of enhanced visual short-term memory for angry faces: An fMRI study

Copyright: © 2008 Jackson et al.Background: Fluid and effective social communication requires that both face identity and emotional expression information are encoded and maintained in visual short-term memory (VSTM) to enable a coherent, ongoing picture of the world and its players. This appears to be of particular evolutionary importance when confronted with potentially threatening displays of emotion - previous research has shown better VSTM for angry versus happy or neutral face identities.Methodology/Principal Findings: Using functional magnetic resonance imaging, here we investigated the neural correlates of this angry face benefit in VSTM. Participants were shown between one and four to-be-remembered angry, happy, or neutral faces, and after a short retention delay they stated whether a single probe face had been present or not in the previous display. All faces in any one display expressed the same emotion, and the task required memory for face identity. We find enhanced VSTM for angry face identities and describe the right hemisphere brain network underpinning this effect, which involves the globus pallidus, superior temporal sulcus, and frontal lobe. Increased activity in the globus pallidus was significantly correlated with the angry benefit in VSTM. Areas modulated by emotion were distinct from those modulated by memory load.Conclusions/Significance: Our results provide evidence for a key role of the basal ganglia as an interface between emotion and cognition, supported by a frontal, temporal, and occipital network.The authors were supported by a Wellcome Trust grant (grant number 077185/Z/05/Z) and by BBSRC (UK) grant BBS/B/16178

Magnetic resonance imaging of gas dynamics in the freeboard of fixed beds and bubbling fluidized beds

Magnetic resonance imaging (MRI) was used to measure directly gas velocity and gas velocity distribution in the freeboard region of a fluidized bed (52 mm dia.) under bubbling fluidization and just below minimum fluidization. The bed consisted of poppy seed particles 1.1 mm in diameter and was fluidized using SF6 gas at 7.5 barg for MRI purposes. In the system, bubbles approximately 20 mm in diameter rose through the centre of the bed. In the case of bubbling fluidization, time-averaged velocity maps at different vertical positions in the freeboard showed downward moving gas in the centre of the bed and upward moving gas near the walls for this particular bed. However, below minimum fluidization conditions, the profiles of gas velocity in the freeboard were flat, with respect to the radial dimension, with minor and random spatial variance, indicating that the profiles observed during bubbling arose from bubble breakthrough. The reasons for these observed patterns of flow are discussed.CMB acknowledges the Gates Cambridge Trust for funding his research.This is the author accepted manuscript. The final version is available from Elsevier via http://dx.doi.org/10.1016/j.ces.2016.03.00

The influence of soil communities on the temperature sensitivity of soil respiration

Soil respiration represents a major carbon flux between terrestrial ecosystems and the atmosphere, and is expected to accelerate under climate warming. Despite its importance in climate change forecasts, however, our understanding of the effects of temperature on soil respiration (RS) is incomplete. Using a metabolic ecology approach we link soil biota metabolism, community composition and heterotrophic activity, to predict RS rates across five biomes. We find that accounting for the ecological mechanisms underpinning decomposition processes predicts climatological RS variations observed in an independent dataset (n = 312). The importance of community composition is evident because without it RS is substantially underestimated. With increasing temperature, we predict a latitudinal increase in RS temperature sensitivity, with Q10 values ranging between 2.33 ±0.01 in tropical forests to 2.72 ±0.03 in tundra. This global trend has been widely observed, but has not previously been linked to soil communities

Identification of complex health interventions suitable for evaluation: development and validation of the 8-step scoping framework

Background: There is extensive literature on the methodology of evaluation research and the development and evaluation of complex interventions but little guidance on the formative stages before evaluation and how to work with partner organizations that wish to have their provision evaluated. It is important to be able to identify suitable projects for evaluation from a range of provision and describe the steps required, often with academic institutions working in partnership with external organizations, in order to set up an evaluation. However, research evaluating programs or interventions rarely discusses these stages. Objective: This study aimed to extend work on evaluability assessment and pre-evaluation planning by proposing an 8-Step Scoping Framework to enable the appraisal of multiple programs in order to identify interventions suitable for evaluation. We aimed to add to the literature on evaluability assessment and more recent evaluation guidance by describing the processes involved in working with partner organizations. Methods: This paper documents the steps required to identify multiple complex interventions suitable for process and outcome evaluation. The steps were developed using an iterative approach by working alongside staff in a local government organization, to build an evidence base to demonstrate which interventions improve children’s outcomes. The process of identifying suitable programs for evaluation, thereby establishing the pre-evaluation steps, was tested using all Flying Start provision. Results: The 8-Step Scoping Framework was described using the example of the local government organization Flying Start to illustrate how each step contributes to finding projects suitable for process and outcome evaluation: (1) formulating overarching key questions that encompass all programs offered by an organization, (2) gaining an in-depth understanding of the work and provision of an organization and engaging staff, (3) completing a data template per project/program offered, (4) assessing the robustness/validity of data across all programs, (5) deciding on projects suitable for evaluation and those requiring additional data, (6) negotiating with chosen project leads, both within and outside the organization, (7) developing individual project evaluation protocols, and (8) applying for ethical approval from the university and partner organization. Conclusions: This paper describes the processes involved in identifying suitable projects for evaluation. It adds to the existing literature on the assessment of specific programs suitable for evaluation and guidance for conducting evaluations by establishing the formative steps required to identify suitable programs from a range of provision. This scoping framework particularly relates to academic partners and organizations tasked with delivering evidence-based services designed to meet local needs. The steps identified have been described in the context of early years provision but can be applied to a range of community-based evaluations, or more generally, to cases where an academic partner is working with external stakeholders to identify projects suitable for academic evaluation

The 10th Biennial Hatter Cardiovascular Institute workshop: cellular protection—evaluating new directions in the setting of myocardial infarction, ischaemic stroke, and cardio-oncology

Due to its poor capacity for regeneration, the heart is particularly sensitive to the loss of contractile cardiomyocytes. The onslaught of damage caused by ischaemia and reperfusion, occurring during an acute myocardial infarction and the subsequent reperfusion therapy, can wipe out upwards of a billion cardiomyocytes. A similar program of cell death can cause the irreversible loss of neurons in ischaemic stroke. Similar pathways of lethal cell injury can contribute to other pathologies such as left ventricular dysfunction and heart failure caused by cancer therapy. Consequently, strategies designed to protect the heart from lethal cell injury have the potential to be applicable across all three pathologies. The investigators meeting at the 10th Hatter Cardiovascular Institute workshop examined the parallels between ST-segment elevation myocardial infarction (STEMI), ischaemic stroke, and other pathologies that cause the loss of cardiomyocytes including cancer therapeutic cardiotoxicity. They examined the prospects for protection by remote ischaemic conditioning (RIC) in each scenario, and evaluated impasses and novel opportunities for cellular protection, with the future landscape for RIC in the clinical setting to be determined by the outcome of the large ERIC-PPCI/CONDI2 study. It was agreed that the way forward must include measures to improve experimental methodologies, such that they better reflect the clinical scenario and to judiciously select combinations of therapies targeting specific pathways of cellular death and injury

Magnetic resonance characterization of coupled gas and particle dynamics in a bubbling fluidized bed

Relative flow between granular material and gas can create phenomena in which particles behave like a liquid with bubbles rising through them. In this paper, magnetic resonance imaging is used to measure the velocities of the gas and solid phases in a bubbling fluidized bed. Comparison with theory shows that the average velocity of gas through the interstices between particles is predicted correctly by classic analytical theory. Experiments were also used to validate predictions from computer simulations of gas and solid motion. The experiments show a wide distribution of gas velocities in both bubbling and emulsion regions, providing a different direction for computational and analytical theory.C.M.B. acknowledges financial support from the Gates Cambridge Trust and Syncrude Canada Ltd