55,734 research outputs found
What Inspires Leisure Time Invention?
This paper seeks to understand the intriguing but only sparsely explored phenomenon of âleisure time invention,â where the main underlying idea for the new product or process occurs when the inventor is away from the workplace. We add to previous research by focussing on the inventive creativity of the individual researcher, and reassessing the image of researchers inventing during unpaid time â who have often been dispatched as âhobbyistsâ. Based on the responses from a survey of over 3,000 German inventors, we tested hypotheses on the conditions under which leisure time invention is likely to arise. Results suggest that the incidence of leisure time invention is positively related to exposure to a variety of knowledge inputs â but, surprisingly, not to the quality of prior inventive output. Leisure time inventions are more frequently observed in conceptual-based technologies than in science-based technologies, in smaller R&D projects, and in externally financed R&D projects
What Inspires Leisure Time Invention?
This paper seeks to understand the intriguing but only sparsely explored phenomenon of âleisure time invention,â where the main underlying idea for the new product or process occurs when the inventor is away from the workplace. We add to previous research by focussing on the inventive creativity of the individual researcher, and reassessing the image of researchers inventing during unpaid time â who have often been dispatched as âhobbyistsâ. Based on the responses from a survey of over 3,000 German inventors, we tested hypotheses on the conditions under which leisure time invention is likely to arise. Results suggest that the incidence of leisure time invention is positively related to exposure to a variety of knowledge inputs â but, surprisingly, not to the quality of prior inventive output. Leisure time inventions are more frequently observed in conceptual-based technologies than in science-based technologies, in smaller R&D projects, and in externally financed R&D projects.Leisure Time; Inventiveness; Organizational Creativity
Bound States Can Stabilize Electroweak Strings
We show that the electroweak string can be stabilized by the presence of
bound states of a complex scalar field. We argue that fermions coupled to the
scalar field of the string can also make the string stable and discuss the
physical case where the string is coupled to quarks and leptons. This
stabilization mechanism is expected to work for other embedded defects and also
for unstable solutions such as the sphaleron.Comment: 11 pages (1 figure available on request), Tufts preprint# TU-92-1
Concepts relating magnetic interactions, intertwined electronic orders and strongly correlated superconductivity
Unconventional superconductivity (SC) is said to occur when Cooper pair
formation is dominated by repulsive electron-electron interactions, so that the
symmetry of the pair wavefunction is other than isotropic s-wave. The strong,
on-site, repulsive electron-electron interactions that are the proximate cause
of such superconductivity are more typically drivers of commensurate magnetism.
Indeed, it is the suppression of commensurate antiferromagnetism (AF) that
usually allows this type of unconventional superconductivity to emerge.
Importantly, however, intervening between these AF and SC phases, intertwined
electronic ordered phases of an unexpected nature are frequently discovered.
For this reason, it has been extremely difficult to distinguish the microscopic
essence of the correlated superconductivity from the often spectacular
phenomenology of the intertwined phases. Here we introduce a model conceptual
framework within which to understand the relationship between antiferromagnetic
electron-electron interactions, intertwined ordered phases and correlated
superconductivity. We demonstrate its effectiveness in simultaneously
explaining the consequences of antiferromagnetic interactions for the
copper-based, iron-based and heavy-fermion superconductors, as well as for
their quite distinct intertwined phases.Comment: Main text + 11 figure
Humans perceive flicker artifacts at 500â Hz.
Humans perceive a stable average intensity image without flicker artifacts when a television or monitor updates at a sufficiently fast rate. This rate, known as the critical flicker fusion rate, has been studied for both spatially uniform lights, and spatio-temporal displays. These studies have included both stabilized and unstablized retinal images, and report the maximum observable rate as 50-90â
Hz. A separate line of research has reported that fast eye movements known as saccades allow simple modulated LEDs to be observed at very high rates. Here we show that humans perceive visual flicker artifacts at rates over 500â
Hz when a display includes high frequency spatial edges. This rate is many times higher than previously reported. As a result, modern display designs which use complex spatio-temporal coding need to update much faster than conventional TVs, which traditionally presented a simple sequence of natural images
Measuring the notched compressive strength of composite laminates: Specimen size effects
Large fibre reinforced composite structures can give much lower strengths than small test specimens, so a proper understanding of scaling is vital for their safe and efficient use. Small size (scale) specimens are commonly tested to justify allowable stresses, but could be dangerous if results are extrapolated without accounting for scaling effects. On the other hand large factors are sometimes applied to compensate for uncertainties, resulting in overweight designs. The most important variables of scaling effects on the strength of composites with open holes have been identified from experimental tests as notch size, ply and laminate thickness. In this study, these have been scaled both independently and simultaneously over a large range of combinations. The specimens are fabricated from commercially available (Hexcel Composites Ltd.) carbon/epoxy pre-impregnated tapes 0.125 mm thick (IM7/8552). The material is laid up by hand in unidirectional [04]ns with n = 2, 3, 4, and 8 (i.e., 2, 3, 4 and 8 mm thick) and multidirectional laminates; two generic quasi-isotropic lay-ups, one fabricated with blocked plies [45n/90n/â45n/0n]s and the other with distributed layers [45/90/â45/0]ns with n = 2, 4 and 8 are examined. It is shown that the critical failure mechanism in these laminates is in the form of fibre microbuckling or kinking. The unnotched compressive strength in unidirectional specimens thicker than 2 mm is found to be limited by the stress concentration developed at the end tabs and manufacturing induced defects in the form of ply waviness, fibre misalignment and voids rather than specimen size (scaling). In the open hole specimens, for both lay-ups, the strength reduction observed is due to hole size effect rather than specimen thickness or volume increase. The open hole (notched) compressive strength results obtained compare favourably to predictions by a linear softening cohesive zone fracture model developed in earlier work by the second author
Reviews Matter: How Distributed Mentoring Predicts Lexical Diversity on Fanfiction.net
Fanfiction.net provides an informal learning space for young writers through
distributed mentoring, networked giving and receiving of feedback. In this
paper, we quantify the cumulative effect of feedback on lexical diversity for
1.5 million authors.Comment: Connected Learning Summit 201
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