Parametrically excited surface waves in magnetic fluids: observation of domain structures

Observations of parametrically excited surface waves in a magnetic fluid are presented. Under the influence of a magnetic field these waves have a non--monotonic dispersion relation, which leads to a richer behavior than in ordinary liquids. We report observation of three novel effects, namely: i) domain structures, ii) oscillating defects and iii) relaxational phase oscillations.Comment: to be published in Physical Review Letter

The Ohio State University Counseling Center: Historical Sketches, 1941-1969

Prepared for the Centennial of The Ohio State University

Enhancing crowdsourcing success: the role of creative and deliberate problem-solving styles

A growing number of firms are using crowdsourcing platforms to actively solicit the skills of external entities to help them solve innovation-related problems. Despite its increasing popularity, crowdsourcing has produced mixed success, because few external experts provide helpful solutions. The current research examines this issue by exploring why some external solvers are more successful than others. Grounded in dual-processing theory, this study combines survey and archival data to assess the impact of creative versus deliberate problem-solving styles on solving success. The results indicate that both styles can be effective, but their relative success depends on the amount of time a solver invests in a solution and his or her degree of contextual familiarity with the problem. Specifically, creative (deliberate) styles are more effective under conditions of high (low) contextual familiarity and shorter (longer) time investments. When solvers employ both styles, overall problem-solving success declines. Data source: surve

Super-lattice, rhombus, square, and hexagonal standing waves in magnetically driven ferrofluid surface

Standing wave patterns that arise on the surface of ferrofluids by (single frequency) parametric forcing with an ac magnetic field are investigated experimentally. Depending on the frequency and amplitude of the forcing, the system exhibits various patterns including a superlattice and subharmonic rhombuses as well as conventional harmonic hexagons and subharmonic squares. The superlattice arises in a bicritical situation where harmonic and subharmonic modes collide. The rhombic pattern arises due to the non-monotonic dispersion relation of a ferrofluid

Ein Jahr Militär-Nervenheilanstalt

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Contribución al estudio del mecanismo de la electromigración en conductores delgados de aluminio

Fil: Mahr von Staszewski, Guillermo G. R.. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina

Response of a ferrofluid to traveling-stripe forcing

We observe the dynamics of waves propagating on the surface of a ferrofluid under the influence of a spatially and temporarily modulated field. In particular, we excite plane waves by a travelling lamellar modulation of the magnetization. By this external driving both the wavelength and the propagation velocity of the waves can be controlled. The amplitude of the excited waves exhibits a resonance phenomenon similar to that of a forced harmonic oscillator. Its analysis reveals the dispersion relation of the free surface waves, from which the critical magnetic field for the onset of the Rosensweig instability can be extrapolated

Leptospirosis followed by Kawasaki-like disease: case report from an adult Swiss patient and review of the literature

Kawasaki disease (KD) is a vasculitis that mostly occurs in children, but rare cases in adults have been reported. We describe the case of a 43-year-old Swiss male who developed symptoms compatible with KD 7 weeks after leptospirosis, which was presumably acquired after swimming in a creek in the Swiss Alps. We performed a literature review and identified 10 other cases (all in children), in which Kawasaki-like disease was diagnosed in the context of leptospirosis. Outcome was favourable in most cases, including our patient. This exceptional case demonstrates both the possibility of autochthonous cases of leptospirosis in Switzerland as well as a possible association of leptospirosis with Kawasaki-like disease