Density-functional studies of tungsten trioxide, tungsten bronzes, and related systems

Tungsten trioxide adopts a variety of structures which can be intercalated with charged species to alter the electronic properties, thus forming `tungsten bronzes'. Similar optical effects are observed upon removing oxygen from WO_3, although the electronic properties are slightly different. Here we present a computational study of cubic and hexagonal alkali bronzes and examine the effects on cell size and band structure as the size of the intercalated ion is increased. With the exception of hydrogen (which is predicted to be unstable as an intercalate), the behaviour of the bronzes are relatively consistent. NaWO_3 is the most stable of the cubic systems, although in the hexagonal system the larger ions are more stable. The band structures are identical, with the intercalated atom donating its single electron to the tungsten 5d valence band. Next, this was extended to a study of fractional doping in the Na_xWO_3 system (0 < x < 1). A linear variation in cell parameter, and a systematic change in the position of the Fermi level up into the valence band was observed with increasing x. In the underdoped WO_3-x system however, the Fermi level undergoes a sudden jump into the conduction band at around x = 0.2. Lastly, three compounds of a layered WO_4&#215;a,wdiaminoalkane hybrid series were studied and found to be insulating, with features in the band structure similar to those of the parent WO_3 compound which relate well to experimental UV-visible spectroscopy results.Comment: 12 pages, 16 figure

Analytical and numerical stability analysis of Soret-driven convection in a horizontal porous layer

We present an analytical and numerical stability analysis of Soret-driven convection in a porous cavity saturated by a binary fluid. Both the mechanical equilibrium solution and the monocellular flow obtained for particular ranges of the physical parameters of the problem are considered. The porous cavity, bounded by horizontal infinite or finite boundaries, is heated from below or from above. The two horizontal plates are maintained at different constant temperatures while no mass flux is imposed. The influence of the governing parameters and more particularly the role of the separation ratio, characterizing the Soret effect and the normalized porosity, are investigated theoretically and numerically. From the linear stability analysis, we find that the equilibrium solution loses its stability via a stationary bifurcation or a Hopf bifurcation depending on the separation ratio and the normalized porosity of the medium. The role of the porosity is important, when it decreases, the stability of the equilibrium solution is reinforced. For a cell heated from below, the equilibrium solution loses its stability via a stationary bifurcation when the separation ratio >0(Le,), while for 0, while a stationary or an oscillatory bifurcation occurs if mono the monocellular flow loses stability via a Hopf bifurcation. As the Rayleigh number increases, the resulting oscillatory solution evolves to a stationary multicellular flow. For a cell heated from above and <0, the monocellular flow remains linearly stable. We verified numerically that this problem admits other stable multicellular stationary solutions for this range of parameters

Statistical assessment of damage to churches affected by the 2010-2011 Canterbury (New Zealand) earthquake sequence

The Canterbury Region of New Zealand experienced an extensive earthquake sequence during 2010-2011, with two particularly severe events being on 4 September 2010 and 22 February 2011. The presented work entails a statistical analysis of the data collected for 112 churches in the affected region, including in situ damage observed by the authors and the structural assessment classification assigned by local authorities. The seismic performance of these churches is discussed and compared with both the structural classifications used in Italy, where a specific survey form for churches is used, and with the building damage classifications assigned by the local authorities

Damage inspection in churches : the Canterbury Earthquake (New Zealand) experience

The Canterbury Region of New Zealand experienced an extensive earthquake sequence during 2010-2011, with two particularly sever events being on September 4, 2010 and February 22, 2011. The present work entails a statistical analysis of the data for 112 churches in the affected region, including in situ damage observed by the authors and the structural assessment classification assigned by the local authorities, allowing for the discussion of the seismic performance of these churches separated in three main typologies: i) stone masonry; ii) clay brick masonry churches; iii) timber churches. A simplified method of assessment of large span masonry structures, which had already been applied to a database of 44 monuments in Italy, Portugal and Spain, was applied with the objective of validating the proposed thresholds. A set of fragility curves, with the objective of estimating damage as a function of the peak ground acceleration, is also provided. It was concluded that the timber churches had an excellent seismic performance, registering only non-structural damage, while the stone and clay brick churches clearly performed unsatisfactorily. The simplified method, which includes three separated indexes, presented very good results for one index (plan area ratio), and acceptable results for the other two (weight ratio and base shear ratio)

Marion: You\u27ll Soon Be Marryin\u27 Me

https://digitalcommons.library.umaine.edu/mmb-vp/2090/thumbnail.jp

An indigenous approach to explore health-related experiences among Māori parents: the Pukapuka Hauora asthma study.

Published onlineJournal ArticleResearch Support, Non-U.S. Gov'tBACKGROUND: The prevalence of asthma for Indigenous New Zealand Māori is amongst the highest in the world. Recent evidence shows ethnic differences in asthma symptom prevalence in New Zealand have widened, with asthma symptoms and hospitalisation rates consistently higher for Māori across all age-groups, especially children and adolescents. This paper: outlines our qualitative, longitudinal research exploring the practical issues Māori children and their families face trying to achieve optimum asthma outcomes; details the research methods used within this study; and discusses the process evaluation findings of the features that made this approach successful in engaging and retaining participants in the study. METHODS: Thirty-two Māori families were recruited using a Kaupapa Māori (Māori way) Research approach. Each participated in a series of four in-depth interviews that were carried out at seasonal intervals over the course of one year. Families also took part in an interviewer-administered questionnaire and participated in a Photovoice exercise. All interviews were digitally recorded, transcribed verbatim and independently coded by two researchers. The research team then conducted the analysis and theme development. The questionnaires were analysed separately, with explanations for findings explored within the qualitative data. RESULTS: The methodology produced a 100 percent retention rate of the participating families over the course of the follow-up. This was attributed to the research collaboration, the respectful research relationships established with families, and the families' judgement that the methods used enabled them to tell their stories. The acceptability of the methodology will add to the validity and trustworthiness of the findings. CONCLUSION: Given the extent and persistence of ethnic disparities in childhood asthma management, it is imperative that an indigenous approach be taken to understanding the core issues facing Māori families. By conducting community-partnership research underpinned by an indigenous methodology, and employing a range of appropriate methods, we have successfully recruited and retained a cohort of Māori families with experiences of childhood asthma. We aim to make their voices heard in order to develop a series of culturally relevant interventions aimed at remediating these disparities.Health Research Council of New ZealandNIH