8,695 research outputs found

    Iron and silicate dust growth in the Galactic interstellar medium: clues from element depletions

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    The interstellar abundances of refractory elements indicate a substantial depletion from the gas phase, that increases with gas density. Our recent model of dust evolution, based on hydrodynamic simulations of the lifecycle of giant molecular clouds (GMCs) proves that the observed trend for [Sigas_{gas}/H] is driven by a combination of dust growth by accretion in the cold diffuse interstellar medium (ISM) and efficient destruction by supernova (SN) shocks (Zhukovska et al. 2016). With an analytic model of dust evolution, we demonstrate that even with optimistic assumptions for the dust input from stars and without destruction of grains by SNe it is impossible to match the observed [Sigas_{gas}/H]nH-n_H relation without growth in the ISM. We extend the framework developed in our previous work for silicates to include the evolution of iron grains and address a long-standing conundrum: ``Where is the interstellar iron?'. Much higher depletion of Fe in the warm neutral medium compared to Si is reproduced by the models, in which a large fraction of interstellar iron (70%) is locked as inclusions in silicate grains, where it is protected from sputtering by SN shocks. The slope of the observed [Fegas_{gas}/H]nH-n_H relation is reproduced if the remaining depleted iron resides in a population of metallic iron nanoparticles with sizes in the range of 1-10nm. Enhanced collision rates due to the Coulomb focusing are important for both silicate and iron dust models to match the observed slopes of the relations between depletion and density and the magnitudes of depletion at high density.Comment: Accepted for publication in the ApJ, 15 pages, 9 figure

    Effects of New Zealand general elections on stock market returns

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    This paper examines stock returns under both National and Labour governments in New Zealand, offering further insight into the existence of the political cycle effect. Findings indicate the existence of a political cycle effect in stock returns, consistent with a number of recent studies performed within both Australia and New Zealand. New Zealand’s right-of-centre National party are found to be associated with significantly higher stock returns during their terms in office than their left-of-centre counterparts, the Labour party. Our findings add to a growing body of literature, particularly outside of the United States, where investors can expect stock returns to vary depending upon the governing political party and can make better investment decisions accordingly

    The suppression of Acacia spp. through exclusion by herbaceous plants

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    Learning from incidents in airworthiness: a novel framework tool for safety analysis

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    peer-reviewedSafe air travel is an expectation that we often invest little or no thought in. Fortunately, the industry has evolved to a stage where major air accidents are rare. Numerous lessons in aviation safety have unfortunately been paid for in the currency of human life. Many segments of the aviation industry support the idea that adverse and unwelcome events can be minimised through diligent reporting of incidents, event analysis and learning. The value of learning from incidents is not well supported in the implementing regulations. Therefore, little or no examination of learning inputs or outputs is required. The intent of the study was to understand how various situations impact on learning from incidents in the continuing airworthiness management segment. To gain an empathetic understanding of the participants and their actions, an interpretative approach was adopted. An analysis of potential research methods and means of data collection was performed. Thirty-four semi-structured taped interviews were carried out. A qualitative analysis process based on Thematic Analysis employing a six- phase approach was used in support of the study. The harvesting of information from incident reporting systems is a necessary input to continuously develop appropriate and effective training material. The inclusion of basic qualification criteria for human factor trainers in regulatory requirements should also be addressed. However, it is questionable if the perpetuation of these measures alone would support more effective delivery and application of lessons learned throughout the segment. One means of addressing this impending issue is to remodel regulatory, operational and training requirements to consider a new approach in the segment. Reflecting a combination of actions, events and conditions in a new basic model for human factor continuation training, may lay the foundations to better elucidate event causation and yield improved safety recommendations in the featured segment

    Viewing and reviewing the Thai economic crisis: Culture and context

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    For many, the International Monetary Fund (IMF) is seen as an inconsiderate dictatorial institution forced upon the struggling emerging economies of this world, yet influenced by Washington! The 1997 economic crisis in Thailand, of which the key feature was the collapse of the Thai Baht on July 2nd 1997, is often argued to not only have been caused by the IMF through its extensive liberalisation conditions recommended in the 1980ร, but further exacerbated by a complex strategy of mismatched policies forced upon the Thai economy after the crisis itself. This research provides an in-depth analysis of the IMF-policy prescription process, to clarify why IMF-policies did not stimulate a quicker economic recovery in Thailand, and why in many cases the policies they prescribed in the aftermath of the crisis have-not come into fruition. This research also offers an understanding of the necessities required for efficient and effective post-crisis recoveries, on a larger scale, not simply in Thailand. Most controversially of all, this research explores the extent of governmental twisting and manipulation of prescribed policies as they infiltrate both the political and cultural economies, a key issue for global development agencies for future policy promotion. The Thai banking sector is used as an industry case-study to analyse how IMF policies were channelled to the grass roots of a sector, and how efficiently; demonstrating the complexities of this process: informational, cultural and political. Whilst this project focuses solely on the experience in Thailand, this research aims to illustrate the complexity of policy implementation, and demonstrate that barriers and constraints to policy execution arise in many different guises. This research does not, however, seek to offer a panacea for the execution of recovery policies for global institutions. From one perspective this research may suggest that in fact no such thing exists, as a key lesson to be learnt from any crisis experience is that the local specificities necessitate tailor-made solutions requiring acute attention to be paid to the local culture and the political system. Thus one of the main outcomes of this research is to demonstrate whether the problems of crisis recovery lie in the reform policies themselves, or their domestic implementation, based on the experiences of the Thai banking sector

    Evaluating Human-equine Interactions Through the Lens of Adult Attachment

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    Attachment Theory suggests interaction with caregivers in childhood impacts relationships and health throughout our lives (Bowlby, 1965, 1969, 1971), leaving many who have experienced insecure attachment with an inability to form healthy relationships or cope with stressors throughout their lifespan (Holmberg, Lomore, Takacs, & Price, 2011). Horses have interacted with humans for over 12,000 years (Hintz, 1995), holding multiple roles in human society, most relying on observation by humans of equine behavior, and formation of a human-equine bond (Hamilton, 2011). More securely attached humans tend to more readily decipher non-verbal cues, positively affecting their felt security and internal working model of Attachment (Bachi, 2013). Interacting with horses, who provide significant non-verbal cues, may provide an opportunity to enhance this process, providing useful feedback and insight. This study aimed to evaluate if a single ground-based encounter with a horse could bring about changes in women participants’ reports of Attachment and Emotion Regulation. It was hypothesized that participants would move towards more secure dimensions of Attachment and Emotion Regulations after the encounter with the horse and that behavioral interactions with the horse would differ for those with differing dimensions of Attachment or Emotion Regulation. This study incorporated a repeated measures mixed methods design, one twenty-eight year old Standardbred mare, “Wicky” Long Wick, interacted with 22 female university students with minimal prior equine experience aged 18-30. Participants completing a demographic and screening questionnaire along with the Experiences in Close Relationships –Revised (ECR)(Brennan, Clark, & Shaver, 1998) and Emotion Regulation Questionnaires (ERQ)(Gross & John, 2003) at baseline, then the ECR and ERQ again both immediately prior to and immediately following encounter with the horse. The encounter was videotaped and included meeting, grooming, leading, and goodbye. Statistical analyses were completed using SPSS including paired t-tests and correlations. Videotape was evaluated, coded, and included in both quantitative and qualitative data analyses. Participants were recruited and participated in the study over the period of one calendar year. A significant decrease in Attachment anxiety was shown after encountering the horse (t(21)=2.915, p=.008 (M .237364, SD= .381941)), and significantly less time was spent between the horse and participant at goodbye than at meeting (t (21)=2.751, p=.021 (M 42.045, SD= 71.67)), particularly for those with insecure dimensions of Attachment (t (15)= 2.814, p=.013 (M= 45.75, SD=65.03)). Participants with insecure dimensions of Attachment showed significant increases in cognitive reappraisal after encountering the horse (t(14)= -3.732, p=.002 (M -.411, SD= .4266)), and the greatest decreases in Attachment Anxiety (t(14)=3.364, p=.005 (M .307, SD= .354)). The findings suggest interaction between horses and people differs along Attachment dimensions and show some support for positive changes in humans for both Attachment and Emotion Regulation dimensions after interaction with a horse
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