960 research outputs found

    Intergenerational Connections and Multidimensional Well-Being in Older Adults in Retirement Communities

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    The purpose of this study was to investigate the relationship between intergenerational connections amongst older adults and younger generations and multiple dimensions of well-being. Cognitive (Mini Mental State Exam), physical [Community Healthy Activities Model Program for Seniors Survey (CHAMPS)], functional [Senior Fitness Test, Katz Index of Activities of Daily Living (ADL), Lawton Instrumental ADL (IADL) Scale], and affective [Geriatric Depression Scale (GDS)] components of well-being were assessed among the target audience of older adults living in independent living communities. A total of 21 subjects sought enrollment in the study. Three subjects were not eligible for the research. Four other subjects did not have a complete data set to analyze. Consequently, the data were underpowered. There were no significant, positive correlations found for social interactions and bicep curl task (p = .206), sit-stand task (p = .073) or GDS (p = .183). Findings did show, however, a significant, positive correlation when comparing Katz Index of ADL and the bicep curl task (p = .045, r = .412) as well as the sit-stand task (p = .043, r = 0.415). In addition, the results of the sit-stand task correlated in a positive manner with the amount of walking as reported on CHAMPS (p = .024, r = .472). Lastly, there was a significant, positive correlation between the number of participants who felt they were impacted by younger generations and the number who felt they impacted younger generations (p \u3c .001, r = .765). Despite being underpowered statistically, the present results do show the positive relationship between physical activity and the perceived value of social interactions for this demographic. Authors encourage more research in this area

    Self-Similar Blowup Solutions to the 2-Component Camassa-Holm Equations

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    In this article, we study the self-similar solutions of the 2-component Camassa-Holm equations% \begin{equation} \left\{ \begin{array} [c]{c}% \rho_{t}+u\rho_{x}+\rho u_{x}=0 m_{t}+2u_{x}m+um_{x}+\sigma\rho\rho_{x}=0 \end{array} \right. \end{equation} with \begin{equation} m=u-\alpha^{2}u_{xx}. \end{equation} By the separation method, we can obtain a class of blowup or global solutions for σ=1\sigma=1 or −1-1. In particular, for the integrable system with σ=1\sigma=1, we have the global solutions:% \begin{equation} \left\{ \begin{array} [c]{c}% \rho(t,x)=\left\{ \begin{array} [c]{c}% \frac{f\left( \eta\right) }{a(3t)^{1/3}},\text{ for }\eta^{2}<\frac {\alpha^{2}}{\xi} 0,\text{ for }\eta^{2}\geq\frac{\alpha^{2}}{\xi}% \end{array} \right. ,u(t,x)=\frac{\overset{\cdot}{a}(3t)}{a(3t)}x \overset{\cdot\cdot}{a}(s)-\frac{\xi}{3a(s)^{1/3}}=0,\text{ }a(0)=a_{0}% >0,\text{ }\overset{\cdot}{a}(0)=a_{1} f(\eta)=\xi\sqrt{-\frac{1}{\xi}\eta^{2}+\left( \frac{\alpha}{\xi}\right) ^{2}}% \end{array} \right. \end{equation} where η=xa(s)1/3\eta=\frac{x}{a(s)^{1/3}} with s=3t;s=3t; ξ>0\xi>0 and α≥0\alpha\geq0 are arbitrary constants.\newline Our analytical solutions could provide concrete examples for testing the validation and stabilities of numerical methods for the systems.Comment: 5 more figures can be found in the corresponding journal paper (J. Math. Phys. 51, 093524 (2010) ). Key Words: 2-Component Camassa-Holm Equations, Shallow Water System, Analytical Solutions, Blowup, Global, Self-Similar, Separation Method, Construction of Solutions, Moving Boundar

    Manifestation of dynamic Jahn-Teller distortions and surface interactions in scanning tunnelling microscopy images of fullerene anion C−60

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    Using scanning tunnelling microscopy (STM), it is possible to observe detailed structure of the molecular orbitals (MOs) of fullerene anions C−60. However, understanding the experimental observations is not straightforward because of the inherent presence of Jahn–Teller (JT) interactions, which (in general) split the MOs in one of a number of equivalent ways. Tunnelling between equivalent distortions means that any observed STM image will be a superposition of images arising from the individual configurations. Interactions with the surface substrate must also be taken into account. We will show how simple ideas involving a symmetry analysis and Hückel molecular orbital theory can be used to understand observed STM images without need for the more usual but more complicated density functional calculations. In particular, we will show that when the fullerene ion is adsorbed with a pentagon, hexagon or double-bond facing the surface, STM images involving the lowest unoccupied molecular orbital (LUMO) can be reproduced by adding together just two images of squares of components of the LUMO, in ratios that depend on the strength of the JT effect and the surface interaction. It should always be possible to find qualitative matches to observed images involving any of these orientations by simply looking at images of the components, without doing any detailed calculations. A comparison with published images indicates that the JT effect in the C−60 ion favours D3d distortions

    Theoretical interpretation of scanning probe microscopy images involving organic molecules

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    Scanning probe microscopy allows the investigation and manipulation of matter at the atomic and molecular level, and is crucial in the development of new and novel techniques within nanoscience. However, to understand the information obtained from the various forms of scanning probe microscopy, a thorough theoretical understanding is necessary. Often this theoretical background is provided through density functional theory, which, while incredibly powerful, has limitations with regards to the size and complexity of the systems in which it can investigate. Thus, for more complicated systems, alternative techniques are desirable to be used both independently and alongside density functional theory. In this work, theoretical techniques are constructed that allow the information obtained from both scanning tunnelling microscopy and atomic force microscopy to be investigated for a variety of systems. These techniques are all based around Huckel molecular orbital theory or extended Huckel molecular orbital theory, and use a simple linear combination of atomic orbital basis, that allows rapid analysis of various systems. The main focus of the work is the scanning probe microscopy of the C60 fullerene molecule. Theoretical scanning tunnelling microscopy images are constructed for the cases where C60 is adsorbed on both the substrate and the scanning probe in the form of a functionalised tip, as well as when a tip-adsorbed molecule interacts with a sample-adsorbed molecule. The atomic force microscopy images of surface adsorbed C60 are considered, with the main focus centred on the repulsive interaction observed due to the Pauli exclusion principle. The structure of the scanning probe, and the effect this has on this imaging is examined, as well as considering the atomic force microscopy images obtained when two C60s interact. Molecules other than C60 are also considered, with the techniques developed used to interpret and understand the atomic force microscopy images obtained when a pentacene and a PTCDA molecule interact with a carbon monoxide functionalised tip. The theoretical work is accompanied throughout by a variety of experimental work, both from previously published work, and from unpublished work obtained by the University of Nottingham nanoscience group. Much focus is given to the interaction between C60 and the Si(111)-(7x7) reconstruction, both in the sense of a functionalised tip interacting with the surface, and with the interactions present where a C60 is adsorbed onto a surface. In doing so, previously postulated bonding sites for C60 on this surface have been verified

    Mexico's Health System: More Comprehensive Reform Needed

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    Jason Lakin discusses and critiques a Policy Forum that reviews 25 years of reform to the Mexican health system and argues that more comprehensive reform is needed

    Theoretical interpretation of scanning probe microscopy images involving organic molecules

    Get PDF
    Scanning probe microscopy allows the investigation and manipulation of matter at the atomic and molecular level, and is crucial in the development of new and novel techniques within nanoscience. However, to understand the information obtained from the various forms of scanning probe microscopy, a thorough theoretical understanding is necessary. Often this theoretical background is provided through density functional theory, which, while incredibly powerful, has limitations with regards to the size and complexity of the systems in which it can investigate. Thus, for more complicated systems, alternative techniques are desirable to be used both independently and alongside density functional theory. In this work, theoretical techniques are constructed that allow the information obtained from both scanning tunnelling microscopy and atomic force microscopy to be investigated for a variety of systems. These techniques are all based around Huckel molecular orbital theory or extended Huckel molecular orbital theory, and use a simple linear combination of atomic orbital basis, that allows rapid analysis of various systems. The main focus of the work is the scanning probe microscopy of the C60 fullerene molecule. Theoretical scanning tunnelling microscopy images are constructed for the cases where C60 is adsorbed on both the substrate and the scanning probe in the form of a functionalised tip, as well as when a tip-adsorbed molecule interacts with a sample-adsorbed molecule. The atomic force microscopy images of surface adsorbed C60 are considered, with the main focus centred on the repulsive interaction observed due to the Pauli exclusion principle. The structure of the scanning probe, and the effect this has on this imaging is examined, as well as considering the atomic force microscopy images obtained when two C60s interact. Molecules other than C60 are also considered, with the techniques developed used to interpret and understand the atomic force microscopy images obtained when a pentacene and a PTCDA molecule interact with a carbon monoxide functionalised tip. The theoretical work is accompanied throughout by a variety of experimental work, both from previously published work, and from unpublished work obtained by the University of Nottingham nanoscience group. Much focus is given to the interaction between C60 and the Si(111)-(7x7) reconstruction, both in the sense of a functionalised tip interacting with the surface, and with the interactions present where a C60 is adsorbed onto a surface. In doing so, previously postulated bonding sites for C60 on this surface have been verified
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