An adaptive Metropolis-Hastings scheme: sampling and optimization

We propose an adaptive Metropolis-Hastings algorithm in which sampled data are used to update the proposal distribution. We use the samples found by the algorithm at a particular step to form the information-theoretically optimal mean-field approximation to the target distribution, and update the proposal distribution to be that approximatio. We employ our algorithm to sample the energy distribution for several spin-glasses and we demonstrate the superiority of our algorithm to the conventional MH algorithm in sampling and in annealing optimization.Comment: To appear in Europhysics Letter

Collective Intelligence for Control of Distributed Dynamical Systems

We consider the El Farol bar problem, also known as the minority game (W. B. Arthur, ``The American Economic Review'', 84(2): 406--411 (1994), D. Challet and Y.C. Zhang, ``Physica A'', 256:514 (1998)). We view it as an instance of the general problem of how to configure the nodal elements of a distributed dynamical system so that they do not ``work at cross purposes'', in that their collective dynamics avoids frustration and thereby achieves a provided global goal. We summarize a mathematical theory for such configuration applicable when (as in the bar problem) the global goal can be expressed as minimizing a global energy function and the nodes can be expressed as minimizers of local free energy functions. We show that a system designed with that theory performs nearly optimally for the bar problem.Comment: 8 page

A low-energy solar cosmic ray experiment for OGO-F

Instrumentation data for low energy solar cosmic ray measurements using OGO-F satellit

Pattern Formation by Boundary Forcing in Convectively Unstable, Oscillatory Media With and Without Differential Transport

Motivated by recent experiments and models of biological segmentation, we analyze the exicitation of pattern-forming instabilities of convectively unstable reaction-diffusion-advection (RDA) systems, occuring by means of constant or periodic forcing at the upstream boundary. Such boundary-controlled pattern selection is a generalization of the flow-distributed oscillation (FDO) mechanism that can include Turing or differential flow instability (DIFI) modes. Our goal is to clarify the relationships among these mechanisms in the general case where there is differential flow as well as differential diffusion. We do so by analyzing the dispersion relation for linear perturbations and showing how its solutions are affected by differential transport. We find a close relationship between DIFI and FDO, while the Turing mechanism gives rise to a distinct set of unstable modes. Finally, we illustrate the relevance of the dispersion relations using nonlinear simulations and we discuss the experimental implications of our results.Comment: Revised version with added content (new section and figures added), changes to wording and organizatio

Measuring what matters to patients: Using goal content to inform measure choice and development

Introduction: Personalised care requires personalised outcomes and ways of feeding back clinically useful information to clinicians and practitioners, but it is not clear how to best personalise outcome measurement and feedback using existing standardised outcome measures. / Method: The constant comparison method of grounded theory was used to compare goal themes derived from goals set at the outset of therapy for 180 children aged between 4 and 17 years, visiting eight child and adolescent mental health services, to existing standardised outcome measures used as part of common national datasets. / Results: In all, 20 out of 27 goal themes corresponded to items on at least one commonly used outcome measure. Discussion: Consideration of goal themes helped to identify potential relevant outcome measures. However, there were several goal themes that were not captured by items on standardised outcome measures. These seemed to be related to existential factors such as understanding, thinking about oneself and future planning. / Conclusion: This presents a powerful framework for how clinicians can use goals to help select a standardised outcome measure (where this is helpful) in addition to the use of a goal-based outcome measure and personalise choices. There may be areas not captured by standardised outcome measures that may be important for children and young people and which may only be currently captured in goal measurement. There is an indication that we may not be measuring what is important to children and young people. We may need to develop or look for new measures that capture these areas

Analytic Continuation for Asymptotically AdS 3D Gravity

We have previously proposed that asymptotically AdS 3D wormholes and black holes can be analytically continued to the Euclidean signature. The analytic continuation procedure was described for non-rotating spacetimes, for which a plane t=0 of time symmetry exists. The resulting Euclidean manifolds turned out to be handlebodies whose boundary is the Schottky double of the geometry of the t=0 plane. In the present paper we generalize this analytic continuation map to the case of rotating wormholes. The Euclidean manifolds we obtain are quotients of the hyperbolic space by a certain quasi-Fuchsian group. The group is the Fenchel-Nielsen deformation of the group of the non-rotating spacetime. The angular velocity of an asymptotic region is shown to be related to the Fenchel-Nielsen twist. This solves the problem of classification of rotating black holes and wormholes in 2+1 dimensions: the spacetimes are parametrized by the moduli of the boundary of the corresponding Euclidean spaces. We also comment on the thermodynamics of the wormhole spacetimes.Comment: 28 pages, 14 figure

Positional Information – a concept underpinning our understanding of developmental biology

© 2019 Wiley Periodicals, Inc.Peer reviewedPostprin

Patient reported outcome measures in child and adolescent mental health services: associations between clinician demographic characteristics, attitudes and efficacy

BACKGROUND: Policy recommends using patient reported outcome measures (PROMs), yet their use is persistently low. Our aim was to examine the association between PROM use and clinician demographic characteristics, attitudes and efficacy. METHOD: A sample of N = 109 clinicians completed an online survey. RESULTS: Clinicians who reported higher levels of use of cognitive behaviour or humanistic approaches had higher levels of PROM use than clinicians who reported lower levels of use of these approaches. Clinicians who reported having received training had higher levels of self-efficacy regarding PROMs than clinicians who reported not having received training, but the effects of training on PROM attitudes and use were not significant. Still, clinicians with more positive attitudes or self-efficacy regarding PROMs had higher levels of PROM use than clinicians with less positive attitudes or self-efficacy regarding PROMs. CONCLUSION: Clinicians should be supported to have the knowledge, skills and confidence to effectively use PROMs in their clinical practice