43 research outputs found

    Fractal Properties of Robust Strange Nonchaotic Attractors in Maps of Two or More Dimensions

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    We consider the existence of robust strange nonchaotic attractors (SNA's) in a simple class of quasiperiodically forced systems. Rigorous results are presented demonstrating that the resulting attractors are strange in the sense that their box-counting dimension is N+1 while their information dimension is N. We also show how these properties are manifested in numerical experiments.Comment: 9 pages, 14 figure

    Magnetic critical behavior of two-dimensional random-bond Potts ferromagnets in confined geometries

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    We present a numerical study of 2D random-bond Potts ferromagnets. The model is studied both below and above the critical value Qc=4Q_c=4 which discriminates between second and first-order transitions in the pure system. Two geometries are considered, namely cylinders and square-shaped systems, and the critical behavior is investigated through conformal invariance techniques which were recently shown to be valid, even in the randomness-induced second-order phase transition regime Q>4. In the cylinder geometry, connectivity transfer matrix calculations provide a simple test to find the range of disorder amplitudes which is characteristic of the disordered fixed point. The scaling dimensions then follow from the exponential decay of correlations along the strip. Monte Carlo simulations of spin systems on the other hand are generally performed on systems of rectangular shape on the square lattice, but the data are then perturbed by strong surface effects. The conformal mapping of a semi-infinite system inside a square enables us to take into account boundary effects explicitly and leads to an accurate determination of the scaling dimensions. The techniques are applied to different values of Q in the range 3-64.Comment: LaTeX2e file with Revtex, revised versio

    Gender, turning points, and boomerangs: returning home in young adulthood in Great Britain

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    The idea of a generation of young adults “boomeranging” back to the parental home has gained widespread currency in the British popular press. However, there is little empirical research identifying either increasing rates of returning home or the factors associated with this trend. This article addresses this gap in the literature using data from a long-running household panel survey to examine the occurrence and determinants of returning to the parental home. We take advantage of the longitudinal design of the British Household Panel Survey (1991–2008) and situate returning home in the context of other life-course transitions. We demonstrate how turning points in an individual’s life course—such as leaving full-time education, unemployment, or partnership dissolution—are key determinants of returning home. An increasingly unpredictable labor market means that graduate employment cannot be taken for granted following university graduation, and returning home upon completion of higher education is becoming normative. We also find that gender moderates the relationship among partnership dissolution, parenthood, and returning to the parental home, reflecting the differential welfare support in Great Britain for single parents compared with nonresident fathers and childless young adults

    Inter-generational ties, financial transfers and home-ownership support

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    <p>Home-ownership is transmitted between generations. Parental gifts form one of the mechanisms through which the intergenerational transmission of home-ownership takes place. Using the Netherlands Kinship Panel Study, we investigated the influence of parental and children's resources and other characteristics on financial support from parents to children. A major independent variable was parental home-ownership. As dependent variables, we distinguished between financial support towards buying a home, and financial support in the form of gifts of a,not sign 5,000 or more ever received. By making this distinction, we could test whether homeowner parents were particularly likely to help their children become homeowners rather than giving other types of financial help. The results did not indicate such specific gift-giving: parental home-ownership was just as important to other types of monetary support as to home-ownership support. However, the distance to the place where the adult child had grown up was negatively associated with receiving home-ownership support but not with receiving other financial transfers.</p>

    Economic Conditions of Young Adults Before and After the Great Recession

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    Transition to adulthood has undoubtedly changed in the last few decades. For youth today, an important marker of adulthood is self-actualization in their professional career, and, consequently, also the achievement of stable financial conditions. Economic conditions of youth are greatly subject to fluctuations in the economy, and the subsequent governmental response. Using the Luxembourg Income Study, this work investigates the trends in income from work of young adults before and after the Great Recession of 2008 in five countries - US, UK, Norway, Germany, and Spain. The findings show deterioration in economic conditions of young men, but with differences across countries. Young women suffer less from the crisis, and in some countries, their economic situation improves. The general negative trend is especially pronounced for those with high education, which is primarily because they stay in education longer

    Readiness for Living Independently Among Emerging Adults With Type 1 Diabetes

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    PURPOSE: The purpose of the study was to examine the association of time (high school to post), living situation (independent of parents or not), diabetes-specific self-efficacy, and worry about hypoglycemia and how diabetes-specific self-efficacy and worry about hypoglycemia are associated with diabetes management among emerging adults with type 1 diabetes. METHODS: Participants (N = 114) completed measures on diabetes management, diabetes-specific self-efficacy, and worry about hypoglycemia during the last 6 months in high school (T1) and diabetes management, diabetes-specific self-efficacy and living situation post high school (T2). General linear mixed model for the diabetes management outcome was used to test associations with diabetes-specific self-efficacy, worry about hypoglycemia, time, and living situation independent variables. Moderation by diabetes-specific self-efficacy and worry about hypoglycemia was also tested. RESULTS: Diabetes management increased from high school to post, but was not significantly associated with living situation (independent of parents or not). Diabetes management was better for youth with greater diabetes-specific self-efficacy. However, neither diabetes-specific self-efficacy nor worry about hypoglycemia moderated the relationship between diabetes management and time or between diabetes management and living situation. CONCLUSIONS: Diabetes management improved over time for these emerging adults with type 1 diabetes. Diabetes-specific self-efficacy is important for diabetes management no matter if youth are in high school or post-high school and if living with parents or not

    Disparities in Osteoporosis Screening Between At-Risk African-American and White Women

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    BACKGROUND: Despite a lower prevalence of osteoporosis in African-American women, they remain at risk and experience a greater mortality than white women after sustaining a hip fracture. Lack of recognition of risk factors may occur in African-American women, raising the possibility that disparities in screening practices may exist. OBJECTIVE: To determine whether there is a difference in physician screening for osteoporosis in postmenopausal, at-risk African-American and white women. METHODS: We conducted a retrospective chart review at an urban academic hospital and a suburban community hospital. Subjects included 205 African-American and white women, age ≥65 years and weight ≤127 pounds, who were seen in Internal Medicine clinics. The main outcome was dual-energy x-ray absorptiometry (DXA) scan referral. We investigated physician and patient factors associated with referral. Secondary outcomes included evidence of discussion of osteoporosis and prescription of medications to prevent osteoporosis. RESULTS: Significantly fewer African-American than white women were referred for a DXA scan (OR 0.39%, 95% confidence interval (CI): 0.22 to 0.68). Physicians were also less likely to mention consideration of osteoporosis in medical records (0.27, 0.15 to 0.48) and to recommend calcium and vitamin D supplementation for this population (0.21, 0.11 to 0.37). If referred, African-American women had comparable DXA completion rates when compared with white women. No physician characteristics were significantly associated with DXA referral patterns. CONCLUSIONS: Our study found a significant disparity in the recommendation for osteoporosis screening for African-American versus white women of similar risk, as well as evidence of disparate osteoporosis prevention and treatment, confirming results of other studies. Future educational and research initiatives should target this inequality
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