1,927 research outputs found

    Collective patterns arising out of spatio-temporal chaos

    Full text link
    We present a simple mathematical model in which a time averaged pattern emerges out of spatio-temporal chaos as a result of the collective action of chaotic fluctuations. Our evolution equation possesses spatial translational symmetry under a periodic boundary condition. Thus the spatial inhomogeneity of the statistical state arises through a spontaneous symmetry breaking. The transition from a state of homogeneous spatio-temporal chaos to one exhibiting spatial order is explained by introducing a collective viscosity which relates the averaged pattern with a correlation of the fluctuations.Comment: 11 pages (Revtex) + 5 figures (postscript

    Stochastic synchronization in globally coupled phase oscillators

    Full text link
    Cooperative effects of periodic force and noise in globally Cooperative effects of periodic force and noise in globally coupled systems are studied using a nonlinear diffusion equation for the number density. The amplitude of the order parameter oscillation is enhanced in an intermediate range of noise strength for a globally coupled bistable system, and the order parameter oscillation is entrained to the external periodic force in an intermediate range of noise strength. These enhancement phenomena of the response of the order parameter in the deterministic equations are interpreted as stochastic resonance and stochastic synchronization in globally coupled systems.Comment: 5 figure

    Forecasting confined spatiotemporal chaos with genetic algorithms

    Get PDF
    A technique to forecast spatiotemporal time series is presented. it uses a Proper Ortogonal or Karhunen-Lo\`{e}ve Decomposition to encode large spatiotemporal data sets in a few time-series, and Genetic Algorithms to efficiently extract dynamical rules from the data. The method works very well for confined systems displaying spatiotemporal chaos, as exemplified here by forecasting the evolution of the onedimensional complex Ginzburg-Landau equation in a finite domain.Comment: 4 pages, 5 figure

    Omnidirectional Stereo

    Get PDF
    Omnidirectional stereo (ODS) is a type of multi-perspective projection that captures horizontal parallax tangential to a viewing circle. This data allows the creation of stereo panoramas that provide plausible stereo views in all viewing directions on the equatorial plane

    Differential Impact of Serial Measurement of Nonplatelet Thromboxane Generation on Long-Term Outcome After Cardiac Surgery.

    Get PDF
    BACKGROUND: Systemic thromboxane generation, not suppressible by standard aspirin therapy and likely arising from nonplatelet sources, increases the risk of atherothrombosis and death in patients with cardiovascular disease. In the RIGOR (Reduction in Graft Occlusion Rates) study, greater nonplatelet thromboxane generation occurred early compared with late after coronary artery bypass graft surgery, although only the latter correlated with graft failure. We hypothesize that a similar differential association exists between nonplatelet thromboxane generation and long-term clinical outcome. METHODS AND RESULTS: Five-year outcome data were analyzed for 290 RIGOR subjects taking aspirin with suppressed platelet thromboxane generation. Multivariable modeling was performed to define the relative predictive value of the urine thromboxane metabolite, 11-dehydrothromboxane B CONCLUSIONS: Long-term nonplatelet thromboxane generation after coronary artery bypass graft surgery is a novel risk factor for 5-year adverse outcome, including death. In contrast, nonplatelet thromboxane generation in the early postoperative period appears to be driven predominantly by inflammation and did not independently predict long-term clinical outcome

    Epigenetic Gene Promoter Methylation at Birth Is Associated With Childā€™s Later Adiposity

    Get PDF
    Objective: fixed genomic variation explains only a small proportion of the risk of adiposity. In animal models, maternal diet alters offspring body composition, accompanied by epigenetic changes in metabolic control genes. Little is known about whether such processes operate in humans.Research design and methods: using Sequenom MassARRAY we measured the methylation status of 68 CpGs 5? from five candidate genes in umbilical cord tissue DNA from healthy neonates. Methylation varied greatly at particular CpGs: for 31 CpGs with median methylation ?5% and a 5ā€“95% range ?10%, we related methylation status to maternal pregnancy diet and to childā€™s adiposity at age 9 years. Replication was sought in a second independent cohort.Results: in cohort 1, retinoid X receptor-? (RXRA) chr9:136355885+ and endothelial nitric oxide synthase (eNOS) chr7:150315553+ methylation had independent associations with sex-adjusted childhood fat mass (exponentiated regression coefficient [?] 17% per SD change in methylation [95% CI 4ā€“31], P = 0.009, n = 64, and ? = 20% [9ā€“32], P < 0.001, n = 66, respectively) and %fat mass (? = 10% [1ā€“19], P = 0.023, n = 64 and ? =12% [4ā€“20], P = 0.002, n = 66, respectively). Regression analyses including sex and neonatal epigenetic marks explained >25% of the variance in childhood adiposity. Higher methylation of RXRA chr9:136355885+, but not of eNOS chr7:150315553+, was associated with lower maternal carbohydrate intake in early pregnancy, previously linked with higher neonatal adiposity in this population. In cohort 2, cord eNOS chr7:150315553+ methylation showed no association with adiposity, but RXRA chr9:136355885+ methylation showed similar associations with fat mass and %fat mass (? = 6% [2ā€“10] and ? = 4% [1ā€“7], respectively, both P = 0.002, n = 239).Conclusions: our findings suggest a substantial component of metabolic disease risk has a prenatal developmental basis. Perinatal epigenetic analysis may have utility in identifying individual vulnerability to later obesity and metabolic diseas

    Clinical Characteristics of Patients Classified as Very High Risk and Not Very High Risk Based on the 2018 AHA/ACC Multi-Society Cholesterol Guideline

    Get PDF
    Background The 2018 AHA/ACC Cholesterol Guideline recommendation to classify ASCVD patients as very high-risk (VHR) vs not-VHR (NVHR) has important implications for ezetimibe and PCSK9 inhibitor eligibility. We aimed to define the clinical characteristics of these two groups within a large multi-state healthcare system in the Western U.S. Methods We performed a retrospective cohort analysis of patients defined as having ASCVD in 2018 using EHR ICD-10 codes. VHR was defined by ā‰„2 major ASCVD events (ACS ā‰¤12 months, history of MI \u3e12 months, ischemic stroke, or symptomatic PAD) or 1 major ASCVD event and ā‰„2 high-risk conditions (age ā‰„65, DM, HTN, smoking, HeFH, CKD, CHF, persistently elevated LDL-C, or prior CABG/PCI). Patients not meeting these criteria were classified as NVHR. Results A total of 180,669 ASCVD patients were identified: 104,123 (58%) were VHR and 76,546 (42%) were NVHR. Mean age and gender was 70.1Ā±13.4 years, 54% male and 73.1Ā±11.9 years, 55% male for the NVHR and VHR groups, respectively. Among patients with a history of MI or recent ACS, 99% and 96% were classified as VHR, respectively (Table). Age ā‰„65, HTN and DM were the most prevalent high-risk conditions. Conclusion Criteria used to predict future CV risk largely divide ASCVD patients into groups of similar prevalence. Nearly all ACS/MI patients were VHR. With growing emphasis on individualized risk assessment and intense LDL-C reduction, opportunity exists to further refine risk prediction within these two at-risk groups

    Time resolved pattern evolution in a large aperture laser

    Full text link
    We have measured quasi-instantaneous transverse patterns in a broad aperture laser. Non-ordered patterns yielding to boundary determined regular structures in progressive time-integrated recording are observed. The linear analysis and numerical integration of the full Maxwell-Bloch equations allow us to interpret the features of the experiment. We show that this system being far from threshold cannot be fully understood with a perturbative model.Comment: 7 pages, 5 GIF figures . To be published in Phys. Rev. Let
    • ā€¦
    corecore