Browsing by Subject "TRANSITION"

Now showing 1 - 5 of 5
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    Analyzing X-ray tomographies of granular packings.
    (The Review of scientific instruments, 2017-05) Weis, Simon; Schröter, Matthias
    Starting from three-dimensional volume data of a granular packing, as, e.g., obtained by X-ray Computed Tomography, we discuss methods to first detect the individual particles in the sample and then analyze their properties. This analysis includes the pair correlation function, the volume and shape of the Voronoi cells, and the number and type of contacts formed between individual particles. We mainly focus on packings of monodisperse spheres, but we will also comment on other monoschematic particles such as ellipsoids and tetrahedra. This paper is accompanied by a package of free software containing all programs (including source code) and an example three-dimensional dataset which allows the reader to reproduce and modify all examples given.
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    Correlation between Voronoi volumes in disc packings
    (EPL (Europhysics Letters), 2012-02-01) Zhao, Song-Chuan; Sidle, Stacy; Swinney, Harry L; Schröter, Matthias
    We measure the two-point correlation of free Voronoi volumes in binary disc packings, where the packing fraction $\phi_{\rm avg}$ ranges from 0.8175 to 0.8380. We observe short-ranged correlations over the whole range of $\phi_{\rm avg}$ and anti-correlations for $\phi_{\rm avg}>0.8277$. The spatial extent of the anti-correlation increases with $\phi_{\rm avg}$ while the position of the maximum of the anti-correlation and the extent of the positive correlation shrink with $\phi_{\rm avg}$. We conjecture that the onset of anti-correlation corresponds to dilatancy onset in this system.
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    Gardner physics in amorphous solids and beyond.
    (The Journal of chemical physics, 2019-07) Berthier, Ludovic; Biroli, Giulio; Charbonneau, Patrick; Corwin, Eric I; Franz, Silvio; Zamponi, Francesco
    One of the most remarkable predictions to emerge out of the exact infinite-dimensional solution of the glass problem is the Gardner transition. Although this transition was first theoretically proposed a generation ago for certain mean-field spin glass models, its materials relevance was only realized when a systematic effort to relate glass formation and jamming was undertaken. A number of nontrivial physical signatures associated with the Gardner transition have since been considered in various areas, from models of structural glasses to constraint satisfaction problems. This perspective surveys these recent advances and discusses the novel research opportunities that arise from them.
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    Physical Activity, Sedentary Behavior, and Retirement: The Multi-Ethnic Study of Atherosclerosis.
    (American journal of preventive medicine, 2018-06) Jones, Sydney A; Li, Quefeng; Aiello, Allison E; O'Rand, Angela M; Evenson, Kelly R
    Physical activity and sedentary behavior are major risk factors for chronic disease. These behaviors may change at retirement, with implications for health in later life. The study objective was to describe longitudinal patterns of moderate to vigorous and domain-specific physical activity and TV watching by retirement status.Participants in the Multi-Ethnic Study of Atherosclerosis (n=6,814) were recruited from six U.S. communities and were aged 45-84 years at baseline. Retirement status and frequency and duration of domain-specific physical activity (recreational walking, transport walking, non-walking leisure activity, caregiving, household, occupational/volunteer) and TV watching were self-reported at four study exams (2000 to 2012). Fixed effect linear regression models were used to describe longitudinal patterns in physical activity and TV watching by retirement status overall and stratified by socioeconomic position. Analyses were conducted in 2017.Of 4,091 Multi-Ethnic Study of Atherosclerosis participants not retired at baseline, 1,012 (25%) retired during a median of 9 years follow-up. Retirement was associated with a 10% decrease (95% CI= -15%, -5%) in moderate to vigorous physical activity and increases of 13% to 29% in recreational walking, household activity, and TV watching. Among people of low socioeconomic position, the magnitude of association was larger for moderate to vigorous physical activity. Among people of high socioeconomic position, the magnitude of association was larger for non-walking leisure and household activity.The retirement transition was associated with changes in physical activity and TV watching. To inform intervention development, future research is needed on the determinants of behavior change after retirement, particularly among individuals of low socioeconomic position.
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    Point, walk, talk: Links between three early milestones, from observation and parental report.
    (Developmental psychology, 2019-08) Moore, Charlotte; Dailey, Shannon; Garrison, Hallie; Amatuni, Andrei; Bergelson, Elika
    Around their first birthdays, infants begin to point, walk, and talk. These abilities are appreciable both by researchers with strictly standardized criteria and caregivers with more relaxed notions of what each of these skills entails. Here, we compare the onsets of these skills and links among them across two data collection methods: observation and parental report. We examine pointing, walking, and talking in a sample of 44 infants studied longitudinally from 6 to 18 months. In this sample, links between pointing and vocabulary were tighter than those between walking and vocabulary, supporting a unified sociocommunicative growth account. Indeed, across several cross-sectional and longitudinal analyses, pointers had larger vocabularies than their nonpointing peers. In contrast to previous work, this did not hold for walkers' versus crawlers' vocabularies in our sample. Comparing across data sources, we find that reported and observed estimates of the growing vocabulary and of age of walk onset were closely correlated, while agreement between parents and researchers on pointing onset and talking onset was weaker. Taken together, these results support a developmental account in which gesture and language are intertwined aspects of early communication and symbolic thinking, whereas the shift from crawling to walking appears indistinct from age in its relation with language. We conclude that pointing, walking, and talking are on similar timelines yet distinct from one another, and discuss methodological and theoretical implications in the context of early development. (PsycINFO Database Record (c) 2019 APA, all rights reserved).