Consistent Application of Maximum Entropy to Quantum-Monte-Carlo Data

Bayesian statistics in the frame of the maximum entropy concept has widely been used for inferential problems, particularly, to infer dynamic properties of strongly correlated fermion systems from Quantum-Monte-Carlo (QMC) imaginary time data. In current applications, however, a consistent treatment of the error-covariance of the QMC data is missing. Here we present a closed Bayesian approach to account consistently for the QMC-data.Comment: 13 pages, RevTeX, 2 uuencoded PostScript figure

Evaluation of elicitation methods to quantify Bayes linear models

The Bayes linear methodology allows decision makers to express their subjective beliefs and adjust these beliefs as observations are made. It is similar in spirit to probabilistic Bayesian approaches, but differs as it uses expectation as its primitive. While substantial work has been carried out in Bayes linear analysis, both in terms of theory development and application, there is little published material on the elicitation of structured expert judgement to quantify models. This paper investigates different methods that could be used by analysts when creating an elicitation process. The theoretical underpinnings of the elicitation methods developed are explored and an evaluation of their use is presented. This work was motivated by, and is a precursor to, an industrial application of Bayes linear modelling of the reliability of defence systems. An illustrative example demonstrates how the methods can be used in practice

Fluorinated liquid crystals: evaluation of selectively fluorinated facially polarised cyclohexyl motifs for liquid crystal applications

The authors thank the European Research Council for and Advanced Grant and DO’H acknowledges the Royal Society for a Wolfson Merit Award.This paper explores the synthesis of a series of prototype negative dielectric liquid crystalline (LC) compounds which contain fluorinated cyclohexane motifs. The series are analogues and differ only in that they contain between one to four fluorine atoms. The stereochemistry is such that all of the fluorines/C-F bonds are on one face of the cyclohexane ring. This follows from the recent recognition that cyclohexanes with fluorines orientated in one direction, perpendicular to the ring have a strong molecular dipole, a characteristic that might be an advantage in the design of negative dielectric materials. However it is found that the increased polarity, particularly with two or more oriented C-F bonds, leads to higher melting points and poorer solubility in test matrix formulations, relative to hydrocarbon liquid crystals. This arises due to electrostatic intermolecular interactions between the polarised cyclohexyl and aryl rings. The study highlights that in order to take advantage of these polar cyclohexane motifs for liquid crystal design, appropriate scaffolds are required which are free of aromatic rings and contain peripheral solubilising motifs.PostprintPostprintPeer reviewe

A risk assessment methodology for the use of lasers in the entertainment industry

Lasers have been used in the entertainment industry since 1964, when they were used in the film Goldfinger. Laser display shows commenced in about 1973. It would be reasonable to expect laser safety to have been adequately addressed over the last twenty-five years. This research showed that the industry was not able to assess the risks from its work. A national survey of the competence of enforcing officers showed that they rarely had the necessary expertise to judge the safety of shows. Therefore, there was often a wide gulf between the laser companies and those responsible for enforcing entertainment and health and safety legislation. A hazard assessment methodology has been developed which considers any laser show as a series of modules which may have different hazards associated with them at different stages of the life cycle, and different people would potentially be exposed to these hazards. A number of laser radiation exposure situations have been assessed, including audience scanning. A theoretical understanding of the laser scanning issues and the application of measurement techniques to enable assessments to be carried out against internationally recognised maximum permissible exposure levels were developed. The conclusion was that the practice of audience scanning was not acceptable in its current form. A number of laser companies worldwide have accepted this view as a direct result of this research. A means of presenting the risk assessment for a laser display has been developed which provides benefits for the laser company, the venue manager, event promoter and the enforcing officer. It is recognised that a complete assessment may not be possible in the time available and a focused approach to the assessment is presented. In summary, if audience scanning is intended, the assessment is complex, but if this practice is not intended then the assessment can be straightforward. Suggestions are made for applying the risk assessment methodology to other laser applications

A Macro-level Approach to Examining Canada’s Primary Industry Towns in a Knowledge Economy

Using a macro-level approach the purpose of this paper is to examine the economic well-being of primary industry communities as well as ascertain if they are adequately preparing to compete in today’s knowledge economy. Large samples of census subdivisions (CSDs) were used to compare primary industry municipalities with diversified municipalities across Canada from 1986 to 2001. In addition, towns that maintained a high percentage of employment in primary industry were compared to ones that diversified their employment base. It was found that diverse municipalities endured a greater era of development and are better positioned for success in the future. Unexpected were results from 1986 to 1996 when diversifying primary industry towns did not incur substantial gains compared to concentrating primary industry communities. From 1996 to 2001 though, it became advantageous for communities to strive towards a diverse economic base. A contributing factor to this phenomenon is the fact that knowledge jobs played a minimal role in diversifying communities from 1991 to 1996. However, from 1996 to 2001 diversifying primary industry towns substantially increased the percentage of jobs related to the knowledge economy. Correlating to this shift in employment structure were positive changes to the socio-economic make up of these towns. Additionally the size and geography of single industry towns are revealed as significant factors for the viability of single industry towns. Utilisant une approche de niveau marco, l’objectif de cet article est d’étudier la santé économique des communautés de l’industrie primaire, et de déterminer si elles sont adéquatement préparées pour faire concurrence dans la nouvelle économie d’aujourd’hui. De grands échantillons de subdivisions recensées (CSDs) ont été utilisés, pour comparer les communautés de l’industrie primaire avec des municipalités à économie diversifiée à travers le Canada, de 1986 à 2001. De plus, les villes ayant maintenu un pourcentage d’emploi élevé dans l’industrie primaire ont été comparées aux municipalités qui ont diversifié leur emploi pendant la même période. Il a été démontré que les municipalités présentant une économie diversifiée vivent un développement durable et sont mieux positionnées pour le succès dans le futur. L’imprévu était le résultat de 1986 à 1996, lorsque les villes ayant diversifié leur industrie primaire n’ont pas obtenu de gains substantiels, en comparaison aux municipalités qui ont concentré leur économie dans le secteur primaire. Cependant, de 1996 à 2001, il devint avantageux pour les communautés de se diriger vers une économie diversifiée. Un des facteur contribuant à ce phénomène est le fait que les emplois hautement spécialisés jouaient un rôle mineur dans les communautés à économie diversifiée de 1986 à 1996. Toutefois, de 1996 à 2001, les villes à économie primaire s’étant tournées vers une économie diversifiée ont augmenté, de manière substantielle, le pourcentage d’emploi relié à l’économie du savoir. Corrélé à ce changement dans la structure de l’emploi, ces villes ont aussi présenté une évolution socio-économique positive

Genome-wide profiling of methylation identifies novel targets with aberrant hyper-methylation and reduced expression in low-risk myelodysplastic syndromes

Gene expression profiling signatures may be used to classify the subtypes of Myelodysplastic syndrome (MDS) patients. However, there are few reports on the global methylation status in MDS. The integration of genome-wide epigenetic regulatory marks with gene expression levels would provide additional information regarding the biological differences between MDS and healthy controls. Gene expression and methylation status were measured using high-density microarrays. A total of 552 differentially methylated CpG loci were identified as being present in low-risk MDS; hypermethylated genes were more frequent than hypomethylated genes. In addition, mRNA expression profiling identified 1005 genes that significantly differed between low-risk MDS and the control group. Integrative analysis of the epigenetic and expression profiles revealed that 66.7% of the hypermethylated genes were underexpressed in low-risk MDS cases. Gene network analysis revealed molecular mechanisms associated with the low-risk MDS group, including altered apoptosis pathways. The two key apoptotic genes BCL2 and ETS1 were identified as silenced genes. In addition, the immune response and micro RNA biogenesis were affected by the hypermethylation and underexpression of IL27RA and DICER1. Our integrative analysis revealed that aberrant epigenetic regulation is a hallmark of low-risk MDS patients and could have a central role in these diseases. © 2013 Macmillan Publishers Limited All rights reserved

Bayesian Inference in Processing Experimental Data: Principles and Basic Applications

This report introduces general ideas and some basic methods of the Bayesian probability theory applied to physics measurements. Our aim is to make the reader familiar, through examples rather than rigorous formalism, with concepts such as: model comparison (including the automatic Ockham's Razor filter provided by the Bayesian approach); parametric inference; quantification of the uncertainty about the value of physical quantities, also taking into account systematic effects; role of marginalization; posterior characterization; predictive distributions; hierarchical modelling and hyperparameters; Gaussian approximation of the posterior and recovery of conventional methods, especially maximum likelihood and chi-square fits under well defined conditions; conjugate priors, transformation invariance and maximum entropy motivated priors; Monte Carlo estimates of expectation, including a short introduction to Markov Chain Monte Carlo methods.Comment: 40 pages, 2 figures, invited paper for Reports on Progress in Physic

Double Strand Breaks Can Initiate Gene Silencing and SIRT1-Dependent Onset of DNA Methylation in an Exogenous Promoter CpG Island

Chronic exposure to inducers of DNA base oxidation and single and double strand breaks contribute to tumorigenesis. In addition to the genetic changes caused by this DNA damage, such tumors often contain epigenetically silenced genes with aberrant promoter region CpG island DNA hypermethylation. We herein explore the relationships between such DNA damage and epigenetic gene silencing using an experimental model in which we induce a defined double strand break in an exogenous promoter construct of the E-cadherin CpG island, which is frequently aberrantly DNA hypermethylated in epithelial cancers. Following the onset of repair of the break, we observe recruitment to the site of damage of key proteins involved in establishing and maintaining transcriptional repression, namely SIRT1, EZH2, DNMT1, and DNMT3B, and the appearance of the silencing histone modifications, hypoacetyl H4K16, H3K9me2 and me3, and H3K27me3. Although in most cells selected after the break, DNA repair occurs faithfully with preservation of activity of the promoter, a small percentage of the plated cells demonstrate induction of heritable silencing. The chromatin around the break site in such a silent clone is enriched for most of the above silent chromatin proteins and histone marks, and the region harbors the appearance of increasing DNA methylation in the CpG island of the promoter. During the acute break, SIRT1 appears to be required for the transient recruitment of DNMT3B and subsequent methylation of the promoter in the silent clones. Taken together, our data suggest that normal repair of a DNA break can occasionally cause heritable silencing of a CpG island–containing promoter by recruitment of proteins involved in silencing. Furthermore, with contribution of the stress-related protein SIRT1, the break can lead to the onset of aberrant CpG island DNA methylation, which is frequently associated with tight gene silencing in cancer

Fact and fiction in housing research: utilizing the creative imagination

As much of our conceptual framework is informed by the experience of the imagination, there is much to be learnt from a study of various creative forms. Narrative fiction can be one such form, allowing us to gain a useful insight into complex features of social life. The purpose of this article is to investigate the treatment of housing issues in contemporary literature in order to gain insights into attitudes, experiences and interpretations from the perspective of a broad cultural milieu. Discussions of professionalism, housing tenure and homelessness have tended to be conducted within a narrow framework and adopted orthodox modes of evaluation. Consequently, the neglect of housing within a wider cultural context has reinforced the isolation of housing issues. The article argues that although discussions of housing and housing policy have been seriously limited within the contemporary novel, there are a number of key insights that can be gained from a discussion of issues within a fictional setting