1,690 research outputs found

    Lipschitz optimization methods for fitting a sum of damped sinusoids to a series of observations

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    A general nonlinear regression model is considered in the form of fitting a sum of damped sinusoids to a series of non-uniform observations. The problem of parameter estimation in this model is important in many applications like signal processing. The corresponding continuous optimization problem is typically difficult due to the high multiextremal character of the objective function. It is shown how Lipschitz-based deterministic methods can be well-suited for studying these challenging global optimization problems, when a limited computational budget is given and some guarantee of the found solution is required

    Optically Active Coordination Compounds. Part 50. 4-Fold Symmetry Axes in Optically Active Complex Ions from Natural Nicotine

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    The synthesis, characterization and circular dichroism under varied conditions (notably pR) of trans-dichloro-tetrakis-(S)-(-)- nicotiniumrhodium(III) salts are described, to illustrate the interplay of chirality of the metal ion (D4) and at carbon centres (C1)

    Hopf solitons in the Nicole model

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    The Nicole model is a conformal field theory in a three-dimensional space. It has topological soliton solutions classified by the integer-valued Hopf charge, and all currently known solitons are axially symmetric. A volume-preserving flow is used to construct soliton solutions numerically for all Hopf charges from 1 to 8. It is found that the known axially symmetric solutions are unstable for Hopf charges greater than 2 and new lower energy solutions are obtained that include knots and links. A comparison with the Skyrme–Faddeev model suggests many universal features, though there are some differences in the link types obtained in the two theories

    Supersymmetric heterotic string backgrounds

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    We present the main features of the solution of the gravitino and dilatino Killing spinor equations derived in hep-th/0510176 and hep-th/0703143 which have led to the classification of geometric types of all type I backgrounds. We then apply these results to the supersymmetric backgrounds of the heterotic string. In particular, we solve the gaugino Killing spinor equation together with the other two Killing spinor equations of the theory. We also use our results to classify all supersymmetry conditions of ten-dimensional gauge theory.Comment: 12 pages, v2: gauge theory applications are stressed and references adde

    Development of a peer-led, network mapping intervention to improve the health of individuals with severe mental illnesses: protocol for a pilot study.

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    INTRODUCTION: Adults with severe mental illness (SMI) have reduced life expectancy and many have comorbid physical health conditions. Primary care providers are experiencing increased demands for care for people with SMI. Barriers to accessing physical healthcare have been identified which negatively affect quality of care. We propose that peer support workers (PSWs) could deliver an intervention to service users to promote their physical health by drawing on existing social support. The aim of this research was to pilot a novel PSW-led intervention, including personal well-being network mapping, to improve access to primary care for physical health needs. METHODS AND ANALYSIS: Twenty-four participants will be recruited from community-based mental health teams in two boroughs of London. Each participant will be offered a six-session intervention. Quantitative data will be collected before and after intervention (at 4-month follow-up). Qualitative interviews will be conducted with PSWs after completion of the intervention and with participants at a 4-month follow-up. Some intervention sessions will be observed by a member of the research team. This is a pilot study with a small sample aiming to assess acceptability and feasibility of an intervention. We aim to use the results to refine the existing theory of change and to optimise the intervention and its evaluation in a future randomised controlled trial. This study is strengthened by its potential clinical importance and origin in previous research where service users engaged with well-being network mapping. ETHICS AND DISSEMINATION: This study has been approved by the London-Chelsea Regional Ethics Committee (ref: 17/LO/0585). The findings will be disseminated to participants, the National Health Service trusts that we recruited from, primary care mental health leads, commissioners and in peer-reviewed journals and academic conferences

    Promoting Supportive Relationships in Youth Programs: A Self-Determination Theory Perspective

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    Although research suggests that positive contact with non-parental adults is developmentally beneficial for youth; many adolescents do not have access to such relationships. It is important that adults structure existing relationships to optimize positive youth development. Relationships with adults, who support youth’s needs for autonomy, relatedness, and competence, provide youth with scaffolding as they navigate their way through adolescence. Self-Determination Theory offers a straight-forward approach to understanding the elements of contexts that best promote the development of supportive relationships. The purpose of this paper is to review the literature concerning youth-adult relationships, including their associated prevalence and developmental benefits across multiple contexts. These findings are then integrated into a framework of best practices for developing and supporting positive youth relationships with adults within youth program settings. Several theory-based recommendations are offered for youth program administrators and staff who wish to improve youth-adult relationships in their programs
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