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

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 [Si$_{gas}$/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 [Si$_{gas}$/H]$-n_H$ 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 [Fe$_{gas}$/H]$-n_H$ 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

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

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

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

Evaluating Human-equine Interactions Through the Lens of Adult Attachment

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

The structure of the perennial growth of Disa uniflora Berg. (Orchidaceae)

The perennation of orchids is poorly understood, in particular that of the Orchidoidae. The understanding of perennation in the Orchidoidae is important because the root-stem tuberoid is used as the one character defining the Orchidoidae as a monophyletic group. The root-stem tuberoid has never been examined for variation before. This project focuses on perennial growth in the Diseae in order to study the structure and function of the root stem tuberoid in relation to other organs and to contribute to the understanding of Orchidoid phylogeny