248 research outputs found

    The Well-Posedness of Solutions for a Generalized Shallow Water Wave Equation

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    A nonlinear partial differential equation containing the famous Camassa-Holm and DegasperisProcesi equations as special cases is investigated. The Kato theorem for abstract differential equations is applied to establish the local well-posedness of solutions for the equation in the Sobolev space H s R with s > 3/2. Although the H 1 -norm of the solutions to the nonlinear model does not remain constant, the existence of its weak solutions in the lower-order Sobolev space H s with 1 ≤ s ≤ 3/2 is proved under the assumptions u 0 ∈ H s and u 0x L ∞ < ∞

    A 2-step penalized regression method for family-based next-generation sequencing association studies

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    Large-scale genetic studies are often composed of related participants, and utilizing familial relationships can be cumbersome and computationally challenging. We present an approach to efficiently handle sequencing data from complex pedigrees that incorporates information from rare variants as well as common variants. Our method employs a 2-step procedure that sequentially regresses out correlation from familial relatedness and then uses the resulting phenotypic residuals in a penalized regression framework to test for associations with variants within genetic units. The operating characteristics of this approach are detailed using simulation data based on a large, multigenerational cohort

    Ethnic differences and heritability of blood pressure circadian rhythm in African and European American youth and young adults

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    Background: The aim of this study was to investigate whether blood pressure (BP) circadian rhythm in African Americans differed from that in European Americans. We further examined the genetic and/or environmental sources of variances of the BP circadian rhythm parameters and the extent to which they depend on ethnicity or sex. Method: Quantification of BP circadian rhythm was obtained using Fourier transformation from the ambulatory BP monitoring data of 760 individuals (mean age, 17.2 +/- 3.3; 322 twin pairs and 116 singletons; 351 African Americans). Results: BP circadian rhythm showed a clear difference by ethnic group with African Americans having a lower amplitude (P = 1.5e-08), a lower percentage rhythm (P = 2.8e-11), a higher MESOR (P = 2.5e-05) and being more likely not to display circadian rhythm (P = 0.002) or not in phase (P = 0.003). Familial aggregation was identified for amplitude, percentage rhythm and acrophase with genetic factors and common environmental factors together accounting for 23 to 33% of the total variance of these BP circadian rhythm parameters. Unique environmental factors were the largest contributor explaining up to 67--77% of the total variance of these parameters. No sex or ethnicity difference in the variance components of BP circadian rhythm was observed. Conclusion: This study suggests that ethnic differences in BP circadian rhythm already exist in youth with African Americans having a dampened circadian rhythm and better BP circadian rhythm may be achieved by changes in environmental factors

    Decreased heritability and emergence of novel genetic effects on pulse wave velocity from youth to young adulthood

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    Increased arterial stiffness measured by pulse wave velocity (PWV) is an important parameter in the assessment of cardiovascular risk. Our previous longitudinal study has demonstrated that carotid-distal PWV showed reasonable stability throughout youth and young adulthood. This stability might be driven by genetic factors that are expressed consistently over time. We aimed to illustrate the relative contributions of genetic and environmental factors to the stability of carotid-distal PWV from youth to young adulthood. We also examined potential ethnic differences. For this purpose, carotid-distal PWV was measured twice in 497 European American (EA) and African American (AA) twins, with an average interval time of 3 years. Twin modelling on PWV showed that heritability decreased over time (62-35%), with the nonshared environmental influences becoming larger. There was no correlation between the nonshared environmental factors on PWV measured at visit 1 and visit 2, with the phenotypic tracking correlation (r=0.32) completely explained by shared genetic factors over time. Novel genetic influences were identified accounting for a significant part of the variance (19%) at the second measurement occasion. There was no evidence for ethnic differences. In summary, novel genetic effects appear during development into young adulthood and account for a considerable part of the variation in PWV. Environmental influences become larger with age for PWV

    Genetic and Environmental Influences on Blood Pressure and Body Mass Index in the National Academy of Sciences-National Research Council World War II Veteran Twin Registry

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    Blood pressure (BP) and obesity phenotypes may covary due to shared genetic or environmental factors or both. Furthermore, it is possible that the heritability of BP differs according to obesity status-a form of GxE interaction. This hypothesis has never been tested in White twins. The present study included 15 924 White male twin pairs aged between 15 and 33 years from the National Academy of Sciences-National Research Council World War II Veteran Twin Registry. Systolic and diastolic BPs, as well as height and weight, were measured at the induction physical examination. Body mass index (BMI) was used as the index of general obesity. Quantitative genetic modeling was performed using Mx software. Univariate analysis showed that narrow sense heritabilities (95% CI) for systolic BP, diastolic BP, height, and BMI were 0.401 (0.381-0.420), 0.297 (0.280-0.320), 0.866 (0.836-0.897), and 0.639 (0.614-0.664), respectively. Positive phenotypic correlations of BMI with systolic BP (r=0.13) and diastolic BP (r=0.08) were largely due to genetic factors (70% and 86%, respectively). The gene-BMI interaction analysis did not show any support for a modifying effect of BMI on genetic and environmental influences of systolic BP and diastolic BP. Our results suggest that correlations between BP and BMI are mainly explained by common genes influencing both. Higher BMI levels have no influence on the penetrance of genetic vulnerability to elevated BP. These conclusions may prove valuable for gene-finding studies

    Economic Research on Energy Storage Auxiliary Frequency Regulation of Lithium Iron Phosphate Battery for 2 × 600 MW Coal-fired Unit in Guangdong

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    [Introduction] In view of the economic benefits of AGC frequency regulation project of combined energy storage in Guangdong coal-fired power plant, the method of establishing typical engineering cases is demonstrated. [Method] This article summarized the latest version of frequency regulation auxiliary market revenue settlement rules in the southern region and calculated the frequency regulation performance index of typical 2 × 600 MW coal-fired units using lithium iron phosphate battery energy storage in Guangdong Province, then established a revenue model, estimated or assumed the key parameters such as cost, mileage, clearing price, running time, etc. Finally, under the contract energy management mode, it calculated its economy from the perspective of investors and analyzed the changes of financial index under different total investment, operation year and revenue sharing. [Result] The results show that in the measured case, except for the first sharing scheme, the internal rate of return of capital in other scenarios all exceeds 7%. [Conclusion] The frequency regulation project of lithium iron phosphate battery energy storage in Guangdong has a good return on investment within four years. After that, investors can still be attracted to participate in this project with the decrease of total investment and the increase of share
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