Quantification and prediction of extreme events in a one-dimensional nonlinear dispersive wave model

The aim of this work is the quantification and prediction of rare events characterized by extreme intensity in nonlinear waves with broad spectra. We consider a one-dimensional non- linear model with deep-water waves dispersion relation, the Majda-McLaughlin-Tabak (MMT) model, in a dynamical regime that is characterized by broadband spectrum and strong non- linear energy transfers during the development of intermittent events with finite-lifetime. To understand the energy transfers that occur during the development of an extreme event we perform a spatially localized analysis of the energy distribution along different wavenumbers by means of the Gabor transform. A stochastic analysis of the Gabor coefficients reveals i) the low-dimensionality of the intermittent structures, ii) the interplay between non-Gaussian statis- tical properties and nonlinear energy transfers between modes, as well as iii) the critical scales (or critical Gabor coefficients) where a critical amount of energy can trigger the formation of an extreme event. We analyze the unstable character of these special localized modes directly through the system equation and show that these intermittent events are due to the interplay of the system nonlinearity, the wave dispersion, and the wave dissipation which mimics wave breaking. These localized instabilities are triggered by random localizations of energy in space, created by the dispersive propagation of low-amplitude waves with random phase. Based on these properties, we design low-dimensional functionals of these Gabor coefficients that allow for the prediction of the extreme event well before the nonlinear interactions begin to occur.Comment: 21 pages, 14 figure

On the lithium content of the globular cluster M92

I use literature data and a new temperature calibration to determine the Li abundances in the globular cluster M 92. Based on the same data, Boesgaard et al. have claimed that there is a dispersion in Li abundances in excess of observational errors. This result has been brought as evidence for Li depletion in metal-poor dwarfs. In the present note I argue that there is no strong evidence for intrinsic dispersion in Li abundances, although a dispersion as large as 0.18 dex is possible. The mean Li abundance, A(Li)=2.36, is in good agreement with recent results for field stars and TO stars in the metal-poor globular cluster NGC 6397. The simplest interpretation is that this constant value represents the primordial Li abundance.Comment: A&A accepte

Including Systematic Uncertainties in Confidence Interval Construction for Poisson Statistics

One way to incorporate systematic uncertainties into the calculation of confidence intervals is by integrating over probability density functions parametrizing the uncertainties. In this note we present a development of this method which takes into account uncertainties in the prediction of background processes, uncertainties in the signal detection efficiency and background efficiency and allows for a correlation between the signal and background detection efficiencies. We implement this method with the Feldman & Cousins unified approach with and without conditioning. We present studies of coverage for the Feldman & Cousins and Neyman ordering schemes. In particular, we present two different types of coverage tests for the case where systematic uncertainties are included. To illustrate the method we show the relative effect of including systematic uncertainties the case of dark matter search as performed by modern neutrino tel escopes.Comment: 23 pages, 10 figures, replaced to match published versio

Comparing proxy rated quality of life of people living with dementia in care homes

Background: Improving quality of life (QOL) for people with dementia is a priority. In care homes, we often rely on proxy ratings from staff and family but we do not know if, or how, they differ in care homes. Methods: We compared 1056 pairs of staff and family DEMQOL-Proxy ratings from 86 care homes across England. We explored factors associated with ratings quantitatively using multilevel modelling and, qualitatively, through thematic analysis of 12 staff and 12 relative interviews. Results: Staff and family ratings were weakly correlated (ρs = 0.35). Median staff scores were higher than family's (104 v. 101; p < 0.001). Family were more likely than staff to rate resident QOL as ‘Poor’ (χ2 = 55.91, p < 0.001). Staff and family rated QOL higher when residents had fewer neuropsychiatric symptoms and severe dementia. Staff rated QOL higher in homes with lower staff:resident ratios and when staff were native English speakers. Family rated QOL higher when the resident had spent longer living in the care home and was a native English. Spouses rated residents’ QOL higher than other relatives. Qualitative results suggest differences arise because staff felt good care provided high QOL but families compared the present to the past. Family judgements centre on loss and are complicated by decisions about care home placement and their understandings of dementia. Conclusion: Proxy reports differ systematically between staff and family. Reports are influenced by the rater:staff and family may conceptualise QOL differently

Investigating green supply chain management practices and performance: the moderating roles of supply chain ecocentricity and traceability

Sustainable supply chain management has become an increasingly important driver of business performance. Understanding the contingent nature of how performance is improved in this context is therefore a critical task for management. We explore the moderating effects of two practices unique to sustainable supply chain - ecocentricity and supply chain traceability - on a firm’s environmental and operating cost performance. Design: Survey data were collected from 248 UK manufacturing firms and analyzed using moderated hierarchical regression. Findings: The results suggest that green supply chain management practices are associated with improvements in both environmental and cost-based performance. Further, higher levels of ecocentricity and supply chain traceability are associated with stronger relationships between green supply chain management practices and cost performance. Contrary to expectations, high levels of supply chain traceability were found to negatively moderate the relationship between green supply chain management practices and environmental performance. Limitations: Our research design was survey-based and cross-sectional. Future studies would benefit from longitudinal research designs that capture the effects of GSCM practices on performance over an extended period. Our survey data is also perceptual; using secondary data to capture environmental performance outcomes, for example, would be another opportunity for future research. Practical Implications: We provide additional support to findings that green supply chain management practices benefit both environmental and cost performance dimensions. In this context, we show that investments by firms in working with a broader set of eco-system partners (ecocentricity) and building supply chain traceability and leads to improved environmental sustainability outcomes. We encourage managers to carefully consider how they conceptualize and monitor their supply chains. Not applicable. Originality: This paper offers several contributions to the research in this area. First, we develop and validate a measurement scale for ecocentricity and supply chain traceability. Second, we show how these two variables – unique to sustainable supply chains – can positively influence firm and environmental performance

The Contribution of Anthropometric Factors to Individual Differences in the Perception of Rhythm

In a sample of 44 human subjects, aged between 18 and 38 years, two distinct measurement procedures were carried out: (1) a psychophysical procedure to determine ‘preferred beat rate’ and (2) standard anthropometry to determine mass and 6 skeletal dimensions. Additionally the factors of sex, age and musicianship were also assessed. ANOVAs were carried out with preferred beat rate as the dependent variable and each of the anthropometric variables as between-subjects factors, partitioned into two levels, defined by the 50th percentile. Significant effects were obtained for age, anthropometric factors and the interaction between age and sex, totalling about 40% of the explainable variance. No significant main effects of sex or musicianship were obtained

Predicting ocean rogue waves from point measurements: An experimental study for unidirectional waves

Rogue waves are strong localizations of the wave field that can develop in different branches of physics and engineering, such as water or electromagnetic waves. Here, we experimentally quantify the prediction potentials of a comprehensive rogue-wave reduced-order precursor tool that has been recently developed to predict extreme events due to spatially localized modulation instability. The laboratory tests have been conducted in two different water wave facilities and they involve unidirectional water waves; in both cases we show that the deterministic and spontaneous emergence of extreme events is well predicted through the reported scheme. Due to the interdisciplinary character of the approach, similar studies may be motivated in other nonlinear dispersive media, such as nonlinear optics, plasma, and solids, governed by similar equations, allowing the early stage of extreme wave detection.United States. Office of Naval Research (Grant N00014-15-1-2381)United States. Army Research Office (Grant W911NF-17-1-0306