3,369 research outputs found

    Multiple Roles in Later Life: Role Enhancement and Conflict and Their Effects on Psychological Well-Being

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    Holding both work and family roles can be a central experience for men and women, young or old. Yet, to date, the bulk of knowledge on holding roles in both domains is specific to young adults, a critical gap as conditions warrant longer work life. This inquiry thus focused on older working men and women (over 50 years of age) with at least one family role (spouse, parent of adult children, caregiver to an aging parent, or grandparent). With survey data from the Health and Retirement Study in 2010 and 2012, latent profile analysis, path analyses, and regressions were conducted to investigate multiple roles in later adulthood: 1) The extent older workers experience role enhancement and conflict between work and family roles because of role stressors and rewards, and patterns of role enhancement and conflict experiences, 2) The extent role enhancement and conflict (a) mediate between role rewards/stressors and psychological well-being (aging self-perceptions, life satisfaction, and depressive symptoms), and (b) interact with each other when exerting their psychological impacts, 3) Gender differences in role enhancement and conflict experiences and in their psychological consequences. Holding multiple roles in later life was characterized predominantly by work and family roles mutually enhancing each other, rather than conflicting with each other, a pattern driven primarily by low role stressors and secondarily by high role rewards. Role enhancement and conflict mediated the effects of role stressors/rewards on psychological well-being, especially on self-perceptions on aging. Interactive effects were also found: Psychological well-being was fostered by work conflicting with and enhancing the family but compromised by a similar circumstance in the family. Finally, gender differences emerged. Women benefitted more than men from multiple sources of role enhancement and from their work role (even when it enhanced and conflicted with the family). Men’s psychological well-being was neutral to multiple sources of role enhancement, enhanced by multiple sources of role conflict, and compromised by later-life family (when it enhanced and conflicted with work). In conclusion, although men and women experienced multiple roles in unique ways, they overwhelmingly benefitted from socially recognized activities from work and family roles

    Negative Refraction of Excitations in the Bose-Hubbard Model

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    Ultracold atoms in optical lattices provide a unique opportunity to study Bose- Hubbard physics. In this work we show that by considering a spatially varying onsite interaction it is possible to manipulate the motion of excitations above the Mott phase in a Bose-Hubbard system. Specifically, we show that it is possible to "engineer" regimes where excitations will negatively refract, facilitating the construction of a flat lens.Comment: 6 pages, 4 figure

    Baseline tests of an autonomous telerobotic system for assembly of space truss structures

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    Several proposed space missions include precision reflectors that are larger in diameter than any current or proposed launch vehicle. Most of these reflectors will require a truss structure to accurately position the reflector panels and these reflectors will likely require assembly in orbit. A research program has been conducted at the NASA Langley Research Center to develop the technology required for the robotic assembly of truss structures. The focus of this research has been on hardware concepts, computer software control systems, and operator interfaces necessary to perform supervised autonomous assembly. A special facility was developed and four assembly and disassembly tests of a 102-strut tetrahedral truss have been conducted. The test procedures were developed around traditional 'pick-and-place' robotic techniques that rely on positioning repeatability for successful operation. The data from two of the four tests were evaluated and are presented in this report. All operations in the tests were controlled by predefined sequences stored in a command file, and the operator intervened only when the system paused because of the failure of an actuator command. The tests were successful in identifying potential pitfalls in a telerobotic system, many of which would not have been readily anticipated or incurred through simulation studies. Addressing the total integrated task, instead of bench testing the component parts, forced all aspects of the task to be evaluated. Although the test results indicate that additional developments should be pursued, no problems were encountered that would preclude automated assembly in space as a viable construction method

    Lens space surgeries on A'Campo's divide knots

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    It is proved that every knot in the major subfamilies of J. Berge's lens space surgery (i.e., knots yielding a lens space by Dehn surgery) is presented by an L-shaped (real) plane curve as a "divide knot" defined by N. A'Campo in the context of singularity theory of complex curves. For each knot given by Berge's parameters, the corresponding plane curve is constructed. The surgery coefficients are also considered. Such presentations support us to study each knot itself, and the relationship among the knots in the set of lens space surgeries.Comment: 26 pages, 19 figures. The proofs of Theorem 1.3 and Lemma 3.5 are written down by braid calculus. Section 4 (on the operation Adding squares) is revised and improved the most. Section 5 is adde

    Runway Incursion Prevention System: Demonstration and Testing at the Dallas/Fort Worth International Airport

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    A Runway Incursion Prevention System (RIPS) was tested at the Dallas-Ft. Worth International Airport (DFW) in October 2000. The system integrated airborne and ground components to provide both pilots and controllers with enhanced situational awareness, supplemental guidance cues, a real-time display of traffic information, and warning of runway incursions in order to prevent runway incidents while also improving operational capability. A series of test runs was conducted using NASA s Boeing 757 research aircraft and a test van equipped to emulate an incurring aircraft. The system was also demonstrated to over 100 visitors from the aviation community. This paper gives an overview of the RIPS, DFW flight test activities, and quantitative and qualitative results of the testing
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