2,712 research outputs found
Health promotion during midlife: The influence of internal health locus of control and future time perspective
Health promoting behaviors are typically categorized as behaviors that move individuals towards optimal health while concurrently decreasing one\u27s susceptibility to disease and illness (Becker & Arnold, 2004; Breslow, 1999). When compared to other developmental age periods, less is known about health promotion in midlife (Merrill & Verbrugge, 1999). Thus, the present study examined the relations among demographic variables, future time perspective, internal health locus of control, and middle-aged adults\u27 engagement in health promotion. Data from 109 middle-aged adults between the ages of 40 and 66 were collected via an online survey. Results indicated that the data fit the model poorly chi2 (df = 6;N = 109) = 13.791 p \u3c .05), CFI = .867, TLI = .667, RMSEA = .110. Despite the poor fit, the path model accounted for a substantial amount of variance in health promotion ( R2 = .30). The model indicated that future time perspective and internal health locus of control were associated with engagement in health promotion. In addition, both age and adults\u27 perceptions of the severity of their chronic health conditions were associated with future time perspective. Findings from this study may help inform the design of health interventions. Specifically, results suggest that interventions should consider integrating future time perspective into a theoretical framework in understanding why middle-aged adults choose to engage in health promotion
Intergenerational Transmission of Health-promoting Behaviors: Examining Participation in Physical Activity between Middle-aged Mothers and their Younger Adult Children
Research has provided considerable evidence that participation in regular physical activity is associated with numerous physical and mental health benefits (Penedo & Dahn, 2005). Despite public health efforts to increase the activity levels adults, only 25% of the U.S. adult population is regularly active and nearly 60% remains sedentary (US Department of Health and Human Services [USDHHS], 2008). A small, but growing, area of research has examined physical activity from an intergenerational or dyadic perspective that considers how involvements in close, personal relationships influence levels of physical activity. In a sample of middle-aged mothers and their younger adult children, the present study had three primary objectives: (a) to examine the relations among well-known predictors of physical activity in younger adulthood and midlife, (b) to examine the relations between individual characteristics and interpersonal variables on physical activity within mother-child dyads, and (c) to examine whether mothers influenced their daughters more strongly than their sons. Data from 48 mother-child dyads between the ages of 18 and 57 were collected via an online survey. Findings from the first research objective indicate an adequate fit of the model to the data for middle-aged mothers (chi2 (df = 2; N = 48) = 2.938, p = .230) and younger adults (chi 2 (df = 3; N = 48) = .288, p = .962). With regard to the second research objective, results indicated an adequate fit of the model to the data chi2 (df = 6; N = 48) = 5.057, p = .537. The hypothesized model explained 2.4% of variance in younger adults\u27 physical activity and 17.5% of variance in middle-aged mothers\u27 physical activity. In addition, standardized beta weights provided support for one actor effect, as mothers\u27 internal health locus of control was positively associated with physical activity. (beta = .42). Research objective three was not supported. Findings from this study may help inform the design of future health interventions. Specifically, the results suggest that personal relationships, such as the relationship one has with a family member, may play a role in understanding participation in physical activity
Numerical calculation of ion runaway distributions
Ions accelerated by electric fields (so-called runaway ions) in plasmas may
explain observations in solar flares and fusion experiments, however
limitations of previous analytic work have prevented definite conclusions. In
this work we describe a numerical solver of the 2D non-relativistic linearized
Fokker-Planck equation for ions. It solves the initial value problem in
velocity space with a spectral-Eulerian discretization scheme, allowing
arbitrary plasma composition and time-varying electric fields and background
plasma parameters. The numerical ion distribution function is then used to
consider the conditions for runaway ion acceleration in solar flares and
tokamak plasmas. Typical time scales and electric fields required for ion
acceleration are determined for various plasma compositions, ion species and
temperatures, and the potential for excitation of toroidal Alfv\'en eigenmodes
during tokamak disruptions is considered.Comment: 25 pages, 8 figure
Effect of partially-screened nuclei on fast-electron dynamics
We analyze the dynamics of fast electrons in plasmas containing partially
ionized impurity atoms, where the screening effect of bound electrons must be
included. We derive analytical expressions for the deflection and slowing-down
frequencies, and show that they are increased significantly compared to the
results obtained with complete screening, already at sub-relativistic electron
energies. Furthermore, we show that the modifications to the deflection and
slowing down frequencies are of equal importance in describing the runaway
current evolution. Our results greatly affect fast-electron dynamics and have
important implications, e.g. for the efficacy of mitigation strategies for
runaway electrons in tokamak devices, and energy loss during relativistic
breakdown in atmospheric discharges.Comment: 6 pages, 3 figures, fixed minor typo
Characterizing catalyst performance of DMCs on PO homopolymerization
Double metal cyanide (DMC) complexes are known effective catalysts for the ring-opening polymerization of propylene oxide to generate polyether polyols (Scheme 1).1,2 The high activity of DMC catalysts relative to basic alkaline catalysts eliminates the need for expensive removal of residual catalyst from the product. Furthermore, the poly(propylene glycol) (PPG) products prepared by DMC catalysts have - contrary to products from alkaline catalysis - a low degree of unsaturation and narrow molecular weight distributions. Latter is advantageous with respect to the resulting low viscosities. A common challenge when applying DMC catalysts is the need for an activation procedure, leading to an induction period of unknown length (Figure 1).2,3 In a larger, usually semibatch process, PO monomer can only be added after the activation has been secured; the concentration of PO must not reach certain limits as its ring-opening is highly exothermal.
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