380 research outputs found

    Sounding the past: three silent films

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    The project was an experiment in linking music and poetry to archive films, not only to provide an enhancing accompaniment but, in some cases, with the aim of making something new which would quite profoundly change the way that these films were perceived by audiences

    Thermoelectric Stability of Cu2Se and Magnetic Phenomena in (Ti, Zr, Hf)NiSn Half-Heusler Alloys

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    Vast amounts of heat are emitted by industrial factories, automobiles and geologic formations. To convert the abundance of heat into usable electricity, stable thermoelectric materials with high conversion efficiencies (or equivalently, large zT values) are essential. In this thesis, I first focus on a superionic conductor, Cu2Se, that is an excellent thermoelectric material, yet known to have dissociation issues in real application conditions. By doping the structure with Sn, I was able to demonstrate improved zT values and increased chemical stability. I describe the homebuilt current stress test that I implemented for emulating a high-temperature power generation setting, which has now become more common in thermoelectric studies of Cu2Se-based materials. In a second project, I formed part of a team that showed that magnetic dopants can augment the thermoelectric conversion efficiencies in a half-Heusler alloy, (Ti, Zr, Hf)NiSn. Here, I detail my study of the low-temperature magnetic properties of the composite materials, including the cluster-glass behavior that is visible in the bifurcation of the zero-field-cooled and field-cooled temperature-dependent magnetic susceptibility. I applied the AC susceptibility technique to witness the evolution of the cluster-glass freezing temperatures as a function of driving frequency and strength of the applied magnetic field. The extensive magnetic characterization is important for the recent acceleration of research on magnetic compounds within the thermoelectrics community. I further discovered that the same half-Heusler composites exhibit a strongly non-monotonic dependence of the heat capacity on applied magnetic field at temperatures below 10 K. In the final project of this thesis, I describe the fitting of multi-level paramagnon and volumetric magnon models to the heat capacity data. Using statistical analysis tools, I show that the two-level paramagnon effect on the heat capacity is the most significant, and could be due to trace impurities or defects within the highly disordered compounds. The Fe added samples exhibit a unique trend of the heat capacity with magnetic field at temperatures lower than 4 K. I derive a magnon model as a possible explanation, yet it overfits the data. In the end, I qualitatively attribute the lowest temperature effect in the Fe-added samples to a magnetotransport effect observed in the second project. Overall, the thesis is primarily motivated by thermoelectrics research, which is seen most directly in the high-temperature thermoelectric property study of Cu2Se. The magnetic half-Heusler alloys that were shown to possess improved thermoelectric properties at high temperatures are then studied for their magnetic properties, magnetotransport and magnetothermodynamics at low temperatures as a way of discovering more fundamental aspects of the compounds.PHDPhysicsUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/162868/1/tpbailey_1.pd

    Modelling multivariate disease rates with a latent structure mixture model

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    Copyright © 2013 SAGE / Statistical Modeling SocietyThere has been considerable recent interest in multivariate modelling of the geographical distribution of morbidity or mortality rates for potentially related diseases. The motivations for this include investigation of similarities or dissimilarities in the risk distribution for the different diseases, as well as ‘borrowing strength’ across disease rates to shrink the uncertainty in geographical risk assessment for any particular disease. A number of approaches to such multivariate modelling have been suggested and this paper proposes an extension to these which may provide a richer range of dependency structures than those encompassed so far. We develop a model which incorporates a discrete mixture of latent structures and argue that this provides potential to represent an enhanced range of correlation structures between diseases at the same time as implicitly allowing for less restrictive spatial correlation structures between geographical units. We compare and contrast our approach to other commonly used multivariate disease models and demonstrate comparative results using data taken from cancer registries on four carcinomas in some 300 geographical units in England, Scotland and Wales

    The Mg/Ca–temperature relationship in brachiopod shells: calibrating a potential palaeoseasonality proxy

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    Brachiopods are long-lived, long-ranging, extant organisms, of which some groups precipitate a relatively diagenetically stable low magnesium calcite shell. Previous work has suggested that the incorporation of Mg into brachiopod calcite may be controlled by temperature (Brand et al., 2013). Here we build upon this work by using laser ablation sampling to define the intra-shell variations in two modern brachiopod species,Terebratulina retusa (Linnaeus, 1758) and Liothyrella neozelanica (Thomson, 1918). We studied three T. retusa shells collected live from the Firth of Lorne, Scotland, which witnessed annual temperature variations on the order of 7 °C, in addition to four L. neozelanica shells, which were dredged from a water depth transect (168–1488 m) off the north coast of New Zealand. The comparison of intra-shell Mg/Ca profiles with shell δ<sup>18</sup>O confirms a temperature control on brachiopod Mg/Ca and supports the use of brachiopod Mg/Ca as a palaeoseasonality indicator. Our preliminary temperature calibrations are Mg/Ca = 1.76 ± 0.27 e<sup>(0.16 ± 0.03)T</sup>, R<sup>2</sup> = 0.75, for T. retusa and Mg/Ca = 0.49 ± 1.27 e<sup>(0.2 ± 0.11)T</sup>, R<sup>2</sup> = 0.32, for L. neozelanica (errors are 95% confidence intervals)

    Grammar for Writing? An investigation into the effect of Contextualised Grammar Teaching on Student Writing

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    publication-status: Publishedtypes: ArticleThe role of grammar instruction in the teaching of writing is contested in most Anglophone countries, with several robust meta-analyses finding no evidence of any beneficial effect. However, existing research is limited in that it only considers isolated grammar instruction and offers no theorisation of an instructional relationship between grammar and writing. This study, drawing on a theorised understanding of grammar as a meaning-making resource for writing development, set out to investigate the impact of contextualised grammar instruction on students’ writing performance. The study adopted a mixed-methods approach, with a randomised controlled trial and a complementary qualitative study. The statistical analyses indicate a positive effect on writing performance for the intervention group (e = 0.21; p<0.001); but the study also indicates that the intervention impact differentially on different sub-groups, benefiting able writers more than weaker writers. The study is significant in being the first to supply rigorous, theorised evidence for the potential benefits of teaching grammar to support development in writing

    The interactions between municipal socioeconomic status and age on hip fracture risk

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    The final publication is available at Springer via http://dx.doi.org/10.1007/s00198-014-2869-0SUMMARY: Age modifies the effect of area-level socioeconomic status (SES) in the risk of fragility hip fractures (HF). For older individuals, the risk of HF increases as SES increases. For younger individuals, risk of HF increases as SES decreases. Our study may help decision-makers to better direct the implementation of political decisions. INTRODUCTION: The effect of socioeconomic status (SES) on hip fracture (HF) incidence remains unclear. The objective of this study is to evaluate the association between HF incidence and municipality-level SES as well as interactions between age and SES. METHODS: From the Portuguese Hospital Discharge Database, we selected hospitalizations (2000-2010) of patients aged 50+, with HF diagnosis (codes 820.x, ICD9-CM), caused by traumas of low/moderate energy, excluding bone cancer cases and readmissions for aftercare. Municipalities were classified according to SES (deprived to affluent) using 2001 Census data. A spatial Bayesian hierarchical regression model (controlling for data heterogeneity and spatial autocorrelation), using the Poisson distribution, was used to quantify the relative risk (RR) of HF, 95% credible interval (95%CrI), and analyze the interaction between age and SES after adjusting for rural conditions. RESULTS: There were 96,905 HF, 77.3% of which were on women who, on average, were older than men (mean age 81.2±8.5 vs 78.2±10.1 years) at admission (p<0.001). In women, there was a lower risk associated with better SES: RR=0.83 (95%CrI 0.65-1.00) for affluent versus deprived. There was an inverse association between SES and HF incidence rate in the youngest and a direct association in the oldest, for both sexes, but significant only between deprived and affluent in older ages (≥75 years). CONCLUSIONS: Interaction between SES and age may be due to inequalities in lifestyles, access to health systems, and preventive actions. These results may help decision-makers to better understand the epidemiology of hip fractures and to better direct the available funding.Programa Operacional Factores de Competitividade (COMPETE)Fundação para a Ciência e a Tecnologia (FCT

    Human Mesenchymal Stromal Cells Decrease Mortality Following Intestinal Ischemia and Reperfusion Injury

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    Background Cellular therapy is a novel treatment option for intestinal ischemia. Bone marrow–derived mesenchymal stromal cells (BMSCs) have previously been shown to abate the damage caused by intestinal ischemia/reperfusion (I/R) injury. We therefore hypothesized that (1) human BMSCs (hBMSCs) would produce more beneficial growth factors and lower levels of proinflammatory mediators compared to differentiated cells, (2) direct application of hBMSCs to ischemic intestine would decrease mortality after injury, and (3) decreased mortality would be associated with an altered intestinal and hepatic inflammatory response. Methods Adult hBMSCs and keratinocytes were cultured on polystyrene flasks. For in vitro experiments, cells were exposed to tumor necrosis factor, lipopolysaccharides, or 2% oxygen for 24 h. Supernatants were then analyzed for growth factors and chemokines by multiplex assay. For in vivo experiments, 8- to 12-wk-old male C57Bl6J mice were anesthetized and underwent a midline laparotomy. Experimental groups were exposed to temporary superior mesenteric artery occlusion for 60 min. Immediately after ischemia, 2 × 106 hBMSCs or keratinocytes in phosphate-buffered saline were placed into the peritoneal cavity. Animals were then closed and allowed to recover for 6 h (molecular/histologic analysis) or 7 d (survival analysis). After 6-h reperfusion, animals were euthanized. Intestines and livers were harvested and analyzed for inflammatory chemokines, growth factors, and histologic changes. Results hBMSCs expressed higher levels of human interleukin (IL) 6, IL-8, vascular endothelial growth factor (VEGF), and epidermal growth factor and lower levels of IL-1, IL-3, IL-7, and granulocyte-monocyte colony-stimulating factor after stimulation. In vivo, I/R resulted in significant mortality (70% mortality), whereas application of hBMSCs after ischemia decreased mortality to 10% in a dose-dependent fashion (P = 0.004). Keratinocyte therapy offered no improvements in mortality above I/R. Histologic profiles were equivalent between ischemic groups, regardless of the application of hBMSCs or keratinocytes. Cellular therapy yielded significantly decreased murine intestinal levels of soluble activin receptor-like kinase 1, betacellulin, and endothelin, whereas increasing levels of eotaxin, monokine induced by gamma interferon (MIG), monocyte chemoattractant protein 1, IL-6, granulocyte colony-stimulating factor (G-CSF), and interferon gamma-induced protein 10 (IP-10) from ischemia were appreciated. hBMSC therapy yielded significantly higher expression of murine intestinal VEGF and lower levels of intestinal MIG compared to keratinocyte therapy. Application of hBMSCs after ischemia yielded significantly lower murine levels of hepatic MIG, IP-10, and G-CSF compared to keratinocyte therapy. Conclusions Human BMSCs produce multiple beneficial growth factors. Direct application of hBMSCs to the peritoneal cavity after intestinal I/R decreased mortality by 60%. Improved outcomes with hBMSC therapy were not associated with improved histologic profiles in this model. hBMSC therapy was associated with higher VEGF in intestines and lower levels of proinflammtory MIG, IP-10, and G-CSF in liver tissue after ischemia, suggesting that reperfusion with hBMSC therapy may alter survival by modulating the systemic inflammatory response to ischemia

    Biclustering models for structured microarray data

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    ©2005 IEEE. Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution to servers or lists, or to reuse any copyrighted component of this work in other works must be obtained from the IEEE.Microarrays have become a standard tool for investigating gene function and more complex microarray experiments are increasingly being conducted. For example, an experiment may involve samples from several groups or may investigate changes in gene expression over time for several subjects, leading to large three-way data sets. In response to this increase in data complexity, we propose some extensions to the plaid model, a biclustering method developed for the analysis of gene expression data. This model-based method lends itself to the incorporation of any additional structure such as external grouping or repeated measures. We describe how the extended models may be fitted and illustrate their use on real data

    On Evidence Weighted Mixture Classification

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    2005 Joint Annual Meeting of the Interface and the Classification Society of North America, St. Louis, Missouri, 8-12 June 2005Calculation of the marginal likelihood or evidence is a problem central to model selection and model averaging in a Bayesian framework. Many sampling methods, especially (Reversible Jump) Markov chain Monte Carlo techniques, have been devised to avoid explicit calculation of the evidence, but they are limited to models with a common parameterisation. It is desirable to extend model averaging to models with disparate architectures and parameterisations. In this paper we present a straightforward general computational scheme for calculating the evidence, applicable to any model for which samples can be drawn from the posterior distribution of parameters conditioned on the data. The scheme is demonstrated on a simple feature subset selection example
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