A fast Monte Carlo algorithm for site or bond percolation

We describe in detail a new and highly efficient algorithm for studying site or bond percolation on any lattice. The algorithm can measure an observable quantity in a percolation system for all values of the site or bond occupation probability from zero to one in an amount of time which scales linearly with the size of the system. We demonstrate our algorithm by using it to investigate a number of issues in percolation theory, including the position of the percolation transition for site percolation on the square lattice, the stretched exponential behavior of spanning probabilities away from the critical point, and the size of the giant component for site percolation on random graphs.Comment: 17 pages, 13 figures. Corrections and some additional material in this version. Accompanying material can be found on the web at http://www.santafe.edu/~mark/percolation

Braving difficult choices alone: children's and adolescents' medical decision making.

OBJECTIVE: What role should minors play in making medical decisions? The authors examined children's and adolescents' desire to be involved in serious medical decisions and the emotional consequences associated with them. METHODS: Sixty-three children and 76 adolescents were presented with a cover story about a difficult medical choice. Participants were tested in one of four conditions: (1) own informed choice; (2) informed parents' choice to amputate; (3) informed parents' choice to continue a treatment; and (4) uninformed parents' choice to amputate. In a questionnaire, participants were asked about their choices, preference for autonomy, confidence, and emotional reactions when faced with a difficult hypothetical medical choice. RESULTS: Children and adolescents made different choices and participants, especially adolescents, preferred to make the difficult choice themselves, rather than having a parent make it. Children expressed fewer negative emotions than adolescents. Providing information about the alternatives did not affect participants' responses. CONCLUSIONS: Minors, especially adolescents, want to be responsible for their own medical decisions, even when the choice is a difficult one. For the adolescents, results suggest that the decision to be made, instead of the agent making the decision, is the main element influencing their emotional responses and decision confidence. For children, results suggest that they might be less able than adolescents to project how they would feel. The results, overall, draw attention to the need to further investigate how we can better involve minors in the medical decision-making process

A 3D dynamical model of the colliding winds in binary systems

We present a 3D dynamical model of the orbital induced curvature of the wind-wind collision region in binary star systems. Momentum balance equations are used to determine the position and shape of the contact discontinuity between the stars, while further downstream the gas is assumed to behave ballistically. An archimedean spiral structure is formed by the motion of the stars, with clear resemblance to high resolution images of the so-called ``pinwheel nebulae''. A key advantage of this approach over grid or smoothed particle hydrodynamic models is its significantly reduced computational cost, while it also allows the study of the structure obtained in an eccentric orbit. The model is relevant to symbiotic systems and Gamma-ray binaries, as well as systems with O-type and Wolf-Rayet stars. As an example application, we simulate the X-ray emission from hypothetical O+O and WR+O star binaries, and describe a method of ray tracing through the 3D spiral structure to account for absorption by the circumstellar material in the system. Such calculations may be easily adapted to study observations at wavelengths ranging from the radio to Gamma-ray.Comment: 16 pages, 24 figures, accepted for publication in MNRA

Radio, X-ray, and gamma-ray Emission Models of the Colliding Winds Binary WR 140

We use hydrodynamical models of the wind-collision region (WCR) in the archetype colliding-wind system WR140 to determine the spatial and spectral distribution of the radio, X-ray and gamma-ray emission from shock accelerated electrons. Our calculations are for orbital phase 0.837 when the observed radio emission is close to maximum. Using the observed thermal X-ray emission together with the radio emission to constrain the mass-loss rates, we find that the O-star mass-loss rate is consistent with recent reductions for O4-5 supergiants. We demonstrate that radio VLBI observations of the WCR fail to constrain the opening angle. The observed low frequency turnover at ~3 GHz in the radio emission is due to free-free absorption, since models based on the Razin effect have an unacceptably large fraction of energy in non-thermal particles. The index of the non-thermal electron energy distribution is flatter than the canonical value for diffusive shock acceleration, namely p<2. Several mechanisms are discussed that could lead to such an index. Tighter constraints on p and the nature of the shocks in WR140 will be obtained from future observations at MeV and GeV energies, for which we generally predict lower fluxes than previous work. Since the high stellar photon fluxes prevent the acceleration of electrons beyond gamma > 1e5-1e6, TeV emission from CWB systems will provide unambiguous evidence of pion-decay emission from accelerated ions. We finish by commenting on the emission and physics of the multiple wind collisions in dense stellar clusters, paying particular attention to the Galactic Centre (abridged).Comment: Accepted by MNRAS, 29 pages, 23 figures; substantial changes made following referee's repor

Erratum to: Methods for evaluating medical tests and biomarkers

[This corrects the article DOI: 10.1186/s41512-016-0001-y.]

Evidence synthesis to inform model-based cost-effectiveness evaluations of diagnostic tests: a methodological systematic review of health technology assessments

Background: Evaluations of diagnostic tests are challenging because of the indirect nature of their impact on patient outcomes. Model-based health economic evaluations of tests allow different types of evidence from various sources to be incorporated and enable cost-effectiveness estimates to be made beyond the duration of available study data. To parameterize a health-economic model fully, all the ways a test impacts on patient health must be quantified, including but not limited to diagnostic test accuracy. Methods: We assessed all UK NIHR HTA reports published May 2009-July 2015. Reports were included if they evaluated a diagnostic test, included a model-based health economic evaluation and included a systematic review and meta-analysis of test accuracy. From each eligible report we extracted information on the following topics: 1) what evidence aside from test accuracy was searched for and synthesised, 2) which methods were used to synthesise test accuracy evidence and how did the results inform the economic model, 3) how/whether threshold effects were explored, 4) how the potential dependency between multiple tests in a pathway was accounted for, and 5) for evaluations of tests targeted at the primary care setting, how evidence from differing healthcare settings was incorporated. Results: The bivariate or HSROC model was implemented in 20/22 reports that met all inclusion criteria. Test accuracy data for health economic modelling was obtained from meta-analyses completely in four reports, partially in fourteen reports and not at all in four reports. Only 2/7 reports that used a quantitative test gave clear threshold recommendations. All 22 reports explored the effect of uncertainty in accuracy parameters but most of those that used multiple tests did not allow for dependence between test results. 7/22 tests were potentially suitable for primary care but the majority found limited evidence on test accuracy in primary care settings. Conclusions: The uptake of appropriate meta-analysis methods for synthesising evidence on diagnostic test accuracy in UK NIHR HTAs has improved in recent years. Future research should focus on other evidence requirements for cost-effectiveness assessment, threshold effects for quantitative tests and the impact of multiple diagnostic tests

Erratum to: Methods for evaluating medical tests and biomarkers

[This corrects the article DOI: 10.1186/s41512-016-0001-y.]

Structure, inter-annual recurrence, and global-scale connectivity of airborne microbial communities

9 páginas, 6 figuras, 1 tabla.Dust coming from the large deserts on Earth, such as the Sahara, can travel long distances and be dispersed over thousands of square kilometers. Remote dust deposition rates are increasing as a consequence of global change and may represent a mechanism for intercontinental microbial dispersal. Remote oligotrophic alpine lakes are particularly sensitive to dust inputs and can serve as sentinels of airbornemicrobial transport and the ecological consequences of accelerated intercontinentalmicrobial migration. In this study, we applied high-throughput sequencing techniques (16S rRNA amplicon pyrosequencing) to characterize the microbial communities of atmospheric deposition collected in the Central Pyrenees (NE Spain) along three years. Additionally, bacteria from soils inMauritania and fromthe air-water interface of high altitude Pyrenean lakeswere also examined. Communities in aerosol deposition varied in time with a strong seasonal component of interannual similarity. Communities fromthe same season tended to resemblemore each other than those fromdifferent seasons. Samples from disparate dates, in turn, slightly tended to have more dissimilar microbial assemblages (i.e., temporal distance decay), overall suggesting that atmospheric deposition may influence sink habitats in a temporally predictable manner. The three habitats examined (soil, deposition, and air-water interface) harbored distinct microbial communities, although airborne samples collected in the Pyrenees during Saharan dust outbreaks were closer to Mauritian soil samples than those collected during no Saharan dust episodes. The three habitats shared c.a. 1.4% of the total number of microbial sequences in the dataset. Such successful immigrantswere spread in different bacterial classes. Overall, this study suggests that local and regional features may generate global trends in the dynamics and distribution of airbornemicrobial assemblages, and that the diversity of viable cells in the high atmosphere is likely higher than previously expected.This research was supported by grants CONSOLIDER GRACCIE CSD2007-00067 from the Spanish Office of Science and Innovation (MICINN), and AERBAC-2 178/2010 and DISPERSAL 829/2013 from the Spanish Ministerio de Medio Ambiente-Red de Parques Nacionales (OAPN). AB was supported by the Spanish FPU predoctoral scholarship program.Peer reviewe

Utilization of Diversity Indices in Evaluating the Effect of a Paper Mill Effluent on Bottom Fauna

Bottom fauna surveys of the Lower Sabine River in the vicinity of Orange, Texas were performed from 1967 to 1969. During this time samples were taken before and after effluent from a black-liquor paper mill was discharge into the Sabine River. Species diversity indices were determined for each station (one station above the discharge canal and four below it). The results obtained indicated that the paper mill effluent was not disturbing the river to a degree that it would cause damage. However, the proximity of Sabine Lake (an estuary) and the very low flow often encountered on the Sabine River makes it imperative that high standards be imposed in treatment of the waste water and that qualified personnel make periodic studies on the river

The integration of music and mathematics education in Catalonia and England: perspectives on theory and practice

The relationship between music and mathematics has often been the subject of discussion, both inside and outside the field of education. As part of an exciting project on a European scale, the paper explores the changing contexts in Catalonia (Spain) and England (UK) in relation to the integrated approach to the teaching of music and mathematics. We analyse three areas: academic literature, the curriculum frameworks and publications and resources prepared by and for teachers. Our findings suggest that due to the more favourable attitude towards cross-curricular approaches in education, more progress has been made in England, in terms of developing resources to support an integrated approach to the teaching of music and mathematics, than in Catalonia. Nonetheless, teachers in both locations are very interested in developing these approaches. Although there is a need for further teacher training and support, there is evidence of progress already being made in schools