The Origin of B-Type Runaway Stars: Non-LTE Abundances as a Diagnostic

There are two accepted mechanisms to explain the origin of runaway OB-type stars: the Binary Supernova Scenario (BSS), and the Cluster Ejection Scenario (CES). In the former, a supernova explosion within a close binary ejects the secondary star, while in the latter close multi-body interactions in a dense cluster cause one or more of the stars to be ejected from the region at high velocity. Both mechanisms have the potential to affect the surface composition of the runaway star. TLUSTY non-LTE model atmosphere calculations have been used to determine atmospheric parameters and carbon, nitrogen, magnesium and silicon abundances for a sample of B-type runaways. These same analytical tools were used by Hunter et al. (2009) for their analysis of 50 B-type open cluster Galactic stars (i.e. non-runaways). Effective temperatures were deduced using the silicon-ionization balance technique, surface gravities from Balmer line profiles and microturbulent velocities derived using the Si spectrum. The runaways show no obvious abundance anomalies when compared with stars in the open clusters. The runaways do show a spread in composition which almost certainly reflects the Galactic abundance gradient and a range in the birthplaces of the runaways in the Galactic disk. Since the observed Galactic abundance gradients of C, N, Mg and Si are of a similar magnitude, the abundance ratios (e.g., N/Mg) are, as obtained, essentially uniform across the sample

Vertical Distribution of Planktic Foraminifera through an Oxygen Minimum Zone: How Assemblages and Shell Morphology Reflect Oxygen Concentrations

Oxygen-depleted regions of the global ocean are rapidly expanding, with important implications for global biogeochemical cycles. However, our ability to make projections of a future deoxygenated ocean is limited by a lack of empirical data with which to test and constrain the behavior of global climatic and oceanographic models. We use depth-stratified plankton tows to demonstrate that some species of planktic foraminifera are adapted to life in the heart of the pelagic Oxygen Minimum Zone (OMZ). In particular, we identify two species, Globorotaloides hexagonus and Hastigerina parapelagica, living within the Eastern Tropical North Pacific OMZ. The shells of the former are preserved in marine sediments and could be used to trace the extent and intensity of low-oxygen pelagic habitats in the fossil record. Additional morphometric analyses of G. hexagonus show that shells found in the lowest oxygen environments are larger, more porous, less dense, and have more chambers in the final whorl. The association of this species with the OMZ and the apparent plasticity of its shell in response to ambient oxygenation invites the use of G. hexagonus shells in sediment cores as potential proxies for both the presence and intensity of overlying OMZs

Synthesis and Investigation into the estrogen receptor antagonist activity of isoflavans and their synthetic derivatives

Background: Breast cancer (BC) is the most invasive and prevalent cancer in women in South Africa, with numbers as high as 1 in 8 women in urban areas and with a large percentage being ER-positive (ER+). ER+ BC cells are reliant on the binding of the natural ligand 17β-estradiol (E2) to ERα and ERβ isoforms which drives tumor growth1. ER antagonists and inhibitors of estrogen synthesis are therefore widely used therapeutic agents in the treatment of BC. Isoflavans are natural products found in many dietary plants. They are phytoestrogens, able to act as natural anti-breast cancer agents, acting as ER antagonists 3. Method: The aim of the study is to investigate the ER antagonist activity of natural isoflavans and their synthetic derivatives. We are synthesizing a small library of non-natural isoflavans which have different substituents at the 4’-position of the isoflavan ring. The synthesis makes use of a [4+2] cycloaddition reaction between an o-quinone methide and the aryl-substituted enol ether based on a method by Gharpure et al2. The synthesized compounds will be tested using a luciferase reporter assay to establish if they have antagonist activity in CV1 cells expressing the ER. Results: Results pending. Conclusion: In this project, we aim to develop new chemistry for isoflavans and to establish isoflavan structure-activity relationships. The results of the study may aid in the future design of more potent ER receptor antagonists for breast cancer therapy

Home practice in Mindfulness-Based Cognitive Therapy and Mindfulness-Based Stress Reduction:A systematic review and meta-analysis of participants' mindfulness practice and its association with outcomes

Mindfulness-Based Cognitive Therapy (MBCT) and Mindfulness-Based Stress Reduction (MBSR) emphasize the importance of mindfulness practice at home as an integral part of the program. However, the extent to which participants complete their assigned practice is not yet clear, nor is it clear whether this practice is associated with positive outcomes. For this systematic review and meta-analysis, searches were performed using Scopus and PubMed for studies published through to the end of 2015, reporting on formal home practice of mindfulness by MBSR or MBCT participants. Across 43 studies (N=1427), the pooled estimate for participants’ home practice was 64% of the assigned amount, equating to about 30 minutes per day, six days per week [95% CI 60 – 69%]. There was substantial heterogeneity associated with this estimate. Across 28 studies (N=898), there was a small but significant association between participants’ self-reported home practice and intervention outcomes (r = 0·26, 95% CI 0·19, – 0·34). MBSR and MBCT participants report completing substantial formal mindfulness practice at home over the eight-week intervention, albeit less than assigned amounts. There is a small but significant association between the extent of formal practice and positive intervention outcomes for a wide range of participants

Examining the factor structure of the 39-item and 15-item versions of the five facet mindfulness questionnaire before and after mindfulness-based cognitive therapy for people with recurrent depression

Research into the effectiveness and mechanisms of mindfulness-based interventions (MBIs) requires reliable and valid measures of mindfulness. The 39-item Five Facet Mindfulness Questionnaire (FFMQ-39) is a measure of mindfulness commonly used to assess change before and after MBIs. However, the stability and invariance of the FFMQ factor structure have not yet been tested before and after an MBI; pre to post comparisons may not be valid if the structure changes over this period. Our primary aim was to examine the factor structure of the FFMQ-39 before and after mindfulness-based cognitive therapy (MBCT) in adults with recurrent depression in remission using confirmatory factor analysis (CFA). Additionally, we examined whether the factor structure of the 15-item version (FFMQ-15) was consistent with that of the FFMQ-39, and whether it was stable over MBCT. Our secondary aim was to assess the general psychometric properties of both versions. CFAs showed that pre-MBCT, a 4-factor hierarchical model (excluding the “observing” facet) best fit the FFMQ-39 and FFMQ-15 data, whereas post-MBCT, a 5-factor hierarchical model best fit the data for both versions. Configural invariance across the time points was not supported for both versions. Internal consistency and sensitivity to change were adequate for both versions. Both FFMQ versions did not differ significantly from each other in terms of convergent validity. Researchers should consider excluding the Observing subscale from comparisons of total scale/subscale scores before and after mindfulness interventions. Current findings support the use of the FFMQ-15 as an alternative measure in research where briefer forms are needed. (PsycINFO Database Record (c) 2016 APA, all rights reserved

Do African manufacturing firms learn from exporting?

In this paper, we use firm-level panel data for the manufacturing sector in four African countries to estimate the effect of exporting on efficiency. Estimating simultaneously a production function and an export regression that control for unobserved firm effects, we find both significant efficiency gains from exporting, supporting the learning- byexporting hypothesis, and evidence for self-selection of more efficient firms into exporting. The evidence of learning-by-exporting suggests that Africa has much to gain from orientating its manufacturing sector towards exporting.

Do African Manufacturing Firms Learn from Exporting?

In this paper, we use firm-level panel data for the manufacturing sector in four African countries to estimate the effect of exporting on efficiency. Estimating simultaneously a production function and an export regression that control for unobserved firm effects, we find both significant efficiency gains from exporting, supporting the learning-byexporting hypothesis, and evidence for self-selection of more efficient firms into exporting. The evidence of learning-by-exporting suggests that Africa has much to gain from orientating its manufacturing sector towards exporting.

Exports and firm-level efficiency in African manufacturing.

In this paper, we use firm-level panel data for the manufacturing sector in four African countries to estimate the effect of exporting on efficiency. Measures of firm-level efficiency using stochastic production frontier models are constructed for the period 1992 to 1995. We find that there are large efficiency gains from exporting both in terms of levels and growth, and contrary to China, the gains are largest for the new entrants to exporting. We control for unobserved heterogeneity using a dynamic model with correlated random effects. Results are robust and consistently, we find evidence of a learning-by-exporting effect as well as self-selection of the most efficient firms into exporting. The effect of exporting on efficiency appears to be larger in this African sample than in comparable studies of other regions which is consistent with the smaller size of domestic markets2000

Research Review: The effects of mindfulness-based interventions on cognition and mental health in children and adolescents - a meta-analysis of randomized controlled trials.

BACKGROUND: Mindfulness based interventions (MBIs) are an increasingly popular way of attempting to improve the behavioural, cognitive and mental health outcomes of children and adolescents, though there is a suggestion that enthusiasm has moved ahead of the evidence base. Most evaluations of MBIs are either uncontrolled or nonrandomized trials. This meta-analysis aims to establish the efficacy of MBIs for children and adolescents in studies that have adopted a randomized, controlled trial (RCT) design. METHODS: A systematic literature search of RCTs of MBIs was conducted up to October 2017. Thirty-three independent studies including 3,666 children and adolescents were included in random effects meta-analyses with outcome measures categorized into cognitive, behavioural and emotional factors. Separate random effects meta-analyses were completed for the seventeen studies (n = 1,762) that used an RCT design with an active control condition. RESULTS: Across all RCTs we found significant positive effects of MBIs, relative to controls, for the outcome categories of Mindfulness, Executive Functioning, Attention, Depression, Anxiety/Stress and Negative Behaviours, with small effect sizes (Cohen's d), ranging from .16 to .30. However, when considering only those RCTs with active control groups, significant benefits of an MBI were restricted to the outcomes of Mindfulness (d = .42), Depression (d = .47) and Anxiety/Stress (d = .18) only. CONCLUSIONS: This meta-analysis reinforces the efficacy of using MBIs for improving the mental health and wellbeing of youth as assessed using the gold standard RCT methodology. Future RCT evaluations should incorporate scaled-up definitive trial designs to further evaluate the robustness of MBIs in youth, with an embedded focus on mechanisms of action

Soft X-ray Photochemistry at the L₂,₃-edges in K₃[Fe(CN)₆], [Co(acac)₃] and [Cp₂Fe][BF₄]

Soft X-ray photoreduction has been observed in K3[Fe(CN)6], [Co(acac)3] and [Cp2Fe][BF4]