5,445 research outputs found

    Self-Organized Criticality in Sheared Suspensions

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    Recent studies reveal that suspensions of neutrally buoyant non-Brownian particles driven by slow periodic shear can undergo a dynamical phase transition between a fluctuating irreversible steady state and an absorbing reversible state. Using a computer model, we show that such systems exhibit self-organized criticality when a finite particle sedimentation velocity vs is introduced. Under periodic shear, these systems evolve, without external intervention, towards the shear-dependent critical concentration ϕc as vs is reduced. This state is characterized by power-law distributions in the lifetime and size of fluctuating clusters. Experiments exhibit similar behavior and, as vs is reduced, yield steady-state values of ϕ that tend towards the ϕc corresponding to the applied shear

    Multiplpe Choice Minority Game With Different Publicly Known Histories

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    In the standard Minority Game, players use historical minority choices as the sole public information to pick one out of the two alternatives. However, publishing historical minority choices is not the only way to present global system information to players when more than two alternatives are available. Thus, it is instructive to study the dynamics and cooperative behaviors of this extended game as a function of the global information provided. We numerically find that although the system dynamics depends on the kind of public information given to the players, the degree of cooperation follows the same trend as that of the standard Minority Game. We also explain most of our findings by the crowd-anticrowd theory.Comment: Extensively revised, to appear in New J Phys, 7 pages with 4 figure

    Spacetime Emergence and General Covariance Transmutation

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    Spacetime emergence refers to the notion that classical spacetime "emerges" as an approximate macroscopic entity from a non-spatio-temporal structure present in a more complete theory of interacting fundamental constituents. In this article, we propose a novel mechanism involving the "soldering" of internal and external spaces for the emergence of spacetime and the twin transmutation of general covariance. In the context of string theory, this mechanism points to a critical four dimensional spacetime background.Comment: 11 pages, v2: version to appear in MPL

    Dispersion Coefficients by a Field-Theoretic Renormalization of Fluid Mechanics

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    We consider subtle correlations in the scattering of fluid by randomly placed obstacles, which have been suggested to lead to a diverging dispersion coefficient at long times for high Peclet numbers, in contrast to finite mean-field predictions. We develop a new master equation description of the fluid mechanics that incorporates the physically relevant fluctuations, and we treat those fluctuations by a renormalization group procedure. We find a finite dispersion coefficient at low volume fraction of disorder and high Peclet numbers.Comment: 4 pages, 1 figure; to appear in Phys. Rev. Let

    ``Superfast'' Reaction in Turbulent Flow with Potential Disorder

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    We explore the regime of ``superfast'' reactivity that has been predicted to occur in turbulent flow in the presence of potential disorder. Computer simulation studies confirm qualitative features of the previous renormalization group predictions, which were based on a static model of turbulence. New renormalization group calculations for a more realistic, dynamic model of turbulence show that the superfast regime persists. This regime, with concentration decay exponents greater than that for a well-mixed reaction, appears to be a general result of the interplay among non-linear reaction kinetics, turbulent transport, and local trapping by potential disorder.Comment: 14 pages. 4 figures. Uses IOP styles. To appear in J. Phys. A: Math. Ge

    Trust as a mediator in the relationship between childhood sexual abuse and IL-6 level in adulthood

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    Childhood sexual abuse (CSA) has been shown to predict the coupling of depression and inflammation in adulthood. Trust within intimate relationships, a core element in marital relations, has been shown to predict positive physical and mental health outcomes, but the mediating role of trust in partners in the association between CSA and inflammation in adulthood requires further study. The present study aimed to examine the impact of CSA on inflammatory biomarkers (IL-6 and IL-1ÎČ) in adults with depression and the mediating role of trust. A cross-sectional survey data set of adults presenting with mood and sleep disturbance was used in the analysis. CSA demonstrated a significant negative correlation with IL-6 level (r = -0.28, p<0. 01) in adults with clinically significant depression, while trust showed a significant positive correlation with IL-6 level (r = 0.36, p < .01). Sobel test and bootstrapping revealed a significant mediating role for trust between CSA and IL-6 level. CSA and trust in partners were revealed to have significant associations with IL-6 level in adulthood. Counterintuitively, the directions of association were not those expected. Trust played a mediating role between CSA and adulthood levels of IL-6. Plausible explanations for these counterintuitive findings are discussed

    A Method to Tackle First Order Differential Equations with Liouvillian Functions in the Solution - II

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    We present a semi-decision procedure to tackle first order differential equations, with Liouvillian functions in the solution (LFOODEs). As in the case of the Prelle-Singer procedure, this method is based on the knowledge of the integrating factor structure.Comment: 11 pages, late

    Modeling and Experimental Verification of an Electromagnetic and Piezoelectric Hybrid Energy Harvester

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    This paper describes mathematical models of an electromagnetic and piezoelectric hybrid energy harvesting system and provides an analysis of the relationship between the resonance frequency and the configuration parameters of the system. An electromagnetic and piezoelectric energy harvesting device was designed and the experimental results showed good agreement with the analytical results. The maximum load power of the hybrid energy harvesting system achieved 4.25 mW at a resonant frequency of 18 Hz when the acceleration was 0.7 g, which is an increase of 15% compared with the 3.62 mW achieved by a single electromagnetic technique

    Initial cardiovascular treatment patterns during the first 90 days following an incident cardiovascular event

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    Aims: The aim of this study was to investigate the initial cardiovascular prescription patterns in patients after their first cardiovascular events, and to identify factors associated with cardiovascular polypharmacy. Methods: This was a cross‐sectional study including patients aged ≄ 45 years with the first record of coronary heart disease (CHD) or stroke between 2007 and 2016 using The Health Improvement Network database. This study investigated the patterns of cardiovascular drugs prescribed during the first 90 days after the first cardiovascular events. Logistic regression was used to examine the association between patients' baseline characteristics and cardiovascular polypharmacy (≄5 cardiovascular drugs). Results: A total of 121,600 (59,843 CHD and 61,757 stroke) patients were included in the study. The mean age was 69.5 ± 11.9 years. The proportion of patients who were prescribed 0–1, 2–3, 4–5 drugs and ≄6 drugs were 11.0%, 29.8%, 38.6% and 20.5%, respectively. Factors associated with cardiovascular polypharmacy were sex (female: OR 0.74, 95% CI 0.72–0.76 vs male), age (75–84 years old: OR 0.50, 0.47–0.53 vs 45–54 years old), smoking status (current smoking: OR 1.29, 1.15–1.24 vs never), body mass index (obesity: OR 1.38, 1.34–1.43 vs normal), deprivation status (most deprived: OR 1.09, 1.04–1.14 vs least deprived) and Charlson comorbidity index (index ≄5: OR 1.25, 1.16–1.35 vs index 0). Conclusion: Multiple cardiovascular drugs treatment was common in patients with CVD in the UK. High‐risk factors of CVD were also associated with cardiovascular polypharmacy. Further studies are warranted to assess the impact of cardiovascular polypharmacy and its interaction on CVD recurrence and mortality
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