A physics-based life prediction methodology for thermal barrier coating systems

A novel mechanistic approach is proposed for the prediction of the life of thermal barrier coating (TBC) systems. The life prediction methodology is based on a criterion linked directly to the dominant failure mechanism. It relies on a statistical treatment of the TBC's morphological characteristics, non-destructive stress measurements and on a continuum mechanics framework to quantify the stresses that promote the nucleation and growth of microcracks within the TBC. The last of these accounts for the effects of TBC constituents' elasto-visco-plastic properties, the stiffening of the ceramic due to sintering and the oxidation at the interface between the thermally insulating yttria stabilized zirconia (YSZ) layer and the metallic bond coat. The mechanistic approach is used to investigate the effects on TBC life of the properties and morphology of the top YSZ coating, metallic low-pressure plasma sprayed bond coat and the thermally grown oxide. Its calibration is based on TBC damage inferred from non-destructive fluorescence measurements using piezo-spectroscopy and on the numerically predicted local TBC stresses responsible for the initiation of such damage. The potential applicability of the methodology to other types of TBC coatings and thermal loading conditions is also discussed

Negative oxygen vacancies in HfO2_2 as charge traps in high-k stacks

We calculated the optical excitation and thermal ionization energies of oxygen vacancies in m-HfO$_2$ using atomic basis sets, a non-local density functional and periodic supercell. The thermal ionization energies of negatively charged V$^-$ and V$^{2-}$ centres are consistent with values obtained by the electrical measurements. The results suggest that negative oxygen vacancies are the likely candidates for intrinsic electron traps in the hafnum-based gate stack devices.Comment: 3 pages, 2 figure

Complementarity and Scientific Rationality

Bohr's interpretation of quantum mechanics has been criticized as incoherent and opportunistic, and based on doubtful philosophical premises. If so Bohr's influence, in the pre-war period of 1927-1939, is the harder to explain, and the acceptance of his approach to quantum mechanics over de Broglie's had no reasonable foundation. But Bohr's interpretation changed little from the time of its first appearance, and stood independent of any philosophical presuppositions. The principle of complementarity is itself best read as a conjecture of unusually wide scope, on the nature and future course of explanations in the sciences (and not only the physical sciences). If it must be judged a failure today, it is not because of any internal inconsistency.Comment: 29 page

Band structures of rare gas solids within the GW approximation

Band structures for solid rare gases (Ne, Ar) have been calculated using the GW approximation. All electron and pseudopotential ab initio calculations were performed using Gaussian orbital basis sets and the dependence of particle-hole gaps and electron affinities on basis set and treatment of core electrons is investigated. All electron GW calculations have a smaller particle-hole gap than pseudopotential GW calculations by up to 0.2 eV. Quasiparticle electron and hole excitation energies, valence band widths and electron affinities are generally in very good agreement with those derived from optical absorption and photoemission measurements.Comment: 7 pages 1 figur

Preliminary economic evaluation of biopharming in New Zealand

From the academic literature, this report derives an economic model or framework for considering biopharming. This model is based on a cost-benefit approach to valuing changes in products and production methods. The model indicates the product dimensions that are likely to be affected by biopharming methods and how these dimensions may affect the costs and benefits of production. It also identifies the uncertainties in existing analyses. Finally, it demonstrates a method by which careful analysis of the economic costs and benefits of biopharming could proceed. Two potential products are discussed using this model: recombinant human lactoferrin (rhLF) produced in cow’s milk and low-GI potatoes

“Five hours to sort out your life”: A qualitative study of university students experience of mental health support

Background: Previous qualitative research suggests that university students feel that current service provision does not meet their needs. Exploring the reasons for this may help to promote service change, encourage the uptake of care, improve outcomes and increase satisfaction within university services. Aims: This study aimed to improve the understanding of how students experience the process of accessing and using mental health support, barriers and facilitators to treatment, and how students would adapt provision to improve experiences. Method: Semi-structured interviews were conducted with 16 full-time students who had used mental health services at university. Data were analysed using thematic analysis. Results: Five higher-order themes were identified: personalisation and informed choice, simplifying the process, feeling abandoned ignored or invisible, stigma, and superiority of private and external services. Sixteen subthemes were identified within these themes. Conclusions: Findings indicate that access to mental health support should be simplified, with collaboration across university and external health and care services, to prevent students feeling lost or abandoned when seeking care. An inclusive approach to support access and provision of services for all presentations of mental health problems should be developed

The efficacy of psychological interventions for the prevention and treatment of mental health disorders in university students: A systematic review and meta-analysis

Background: Mental health problems are becoming increasingly prevalent among students and adequate support should be provided to prevent and treat mental health disorders in those at risk. / Methods: This systematic review and meta-analysis examined the efficacy of psychological interventions for students, with consideration of how adaptions to intervention content and delivery could improve outcomes. We searched for randomised controlled trials (RCTs) of interventions in students with or at risk of mental health problems and extracted data for study characteristics, symptom severity, wellbeing, educational outcomes, and attrition. Eighty-four studies were included. / Results: Promising effects were found for indicated and selective interventions to treat anxiety disorders, depression and eating disorders. PTSD and self-harm data was limited, and did not demonstrate significant effects. Relatively few trials adapted intervention delivery to student-specific concerns, and overall adapted interventions showed no benefit over non-adapted interventions. There was some suggestion that adaptions based on empirical evidence and provision of additional sessions, and transdiagnostic models may yield some benefits. / Limitations: The review is limited by the often poor quality of the literature and exclusion of non-published data. / Conclusions: Interventions for students show benefit though uncertainty remains around how best to optimise treatment delivery and content for students. Additional research into content targeting specific underlying mechanisms of problems and transdiagnostic approaches to provision could be promising avenues for further research

Correlated Anisotropies in the Cosmic Far-Infrared Background Detected by MIPS/Spitzer: Constraint on the Bias

We report the detection of correlated anisotropies in the Cosmic Far-Infrared Background at 160 microns. We measure the power spectrum in the Spitzer/SWIRE Lockman Hole field. It reveals unambiguously a strong excess above cirrus and Poisson contributions, at spatial scales between 5 and 30 arcminutes, interpreted as the signature of infrared galaxy clustering. Using our model of infrared galaxy evolution we derive a linear bias b=1.74 \pm 0.16. It is a factor 2 higher than the bias measured for the local IRAS galaxies. Our model indicates that galaxies dominating the 160 microns correlated anisotropies are at z~1. This implies that infrared galaxies at high redshifts are biased tracers of mass, unlike in the local Universe.Comment: ApJ Letters, in pres