7,747 research outputs found

    Making Memories: Location-based Learning on the Erie Canal at a National Historical Park

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    Onsite educational programming at National Parks provides groups with a unique opportunity to interact with history and science. How can Women’s Rights National Historical Park be used to create an onsite educational tour and program that will deliver a memorable experience for their visitors? I conducted research on the history and anthropological consequences of the Erie Canal for an onsite program that will be implemented by the National Park Service. An example interpretive tour route is included that examines the significance of the Erie Canal for the movement of people, the local economy, the movement of ideas and religion, and human rights activism of Seneca Falls, New York, and the United States. Onsite programming gives families and school-groups opportunities to engage with ideas in new ways and create memory-making learning opportunities

    Maximum occupation number for composite boson states

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    One of the major differences between fermions and bosons is that fermionic states have a maximum occupation number of one, whereas the occupation number for bosonic states is in principle unlimited. For bosons that are made up of fermions, one could ask the question to what extent the Pauli principle for the constituent fermions would limit the boson occupation number. Intuitively one can expect the maximum occupation number to be proportional to the available volume for the bosons divided by the volume occupied by the fermions inside one boson, though a rigorous derivation of this result has not been given before. In this letter we show how the maximum occupation number can be calculated from the ground-state energy of a fermionic generalized pairing problem. A very accurate analytical estimate of this eigenvalue is derived. From that a general expression is obtained for the maximum occupation number of a composite boson state, based solely on the intrinsic fermionic structure of the bosons. The consequences for Bose-Einstein condensates of excitons in semiconductors and ultra cold trapped atoms are discussed.Comment: 4 pages, Revte

    Chargino and neutralino searches at LEP

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    In the year 2000, the LEP e/sup +/e/sup -/ collider has been operated up to a centre-of-mass energy of 209 GeV. Each of the four LEP experiments, ALEPH, DELPHI, L3 and OPAL has collected an integral luminosity of about 220 pb/sup -1/. Particle searches have been performed covering a wide range of supersymmetry models. This note describes the searches for charginos and neutralinos in case of some dedicated scenarios. The implications of the chosen scenario on the search strategy are explained and recent results are presented. (9 refs)

    Adhesion and Cellular Compatibility of Silicone-Based Skin Adhesives

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    Pressure-sensitive adhesives based on silicone materials have emerging potential as adhesives in healthcare products, in particular for gentle skin adhesives. To this end, adhesion to rough skin and biocompatibility are crucial factors for a successful implementation. In this study, the mechanical, adhesive, and biological properties of the two-component poly(dimethylsiloxane) Soft Skin Adhesive MG 7-9800 (SSA, Dow Corning) have been investigated and compared to Sylgard 184. Different mixing ratios of SSA's components allow for tuning of the shear modulus, thereby modifying the adhesive properties of the polymer. To give a comprehensive insight, the authors have analyzed the interplay between pull-off stress, adhesion energy, and stretch of the adhesive films on smooth and rough surfaces. The focus is placed on the effects of substrate roughness and on low pressure oxygen plasma treatment of the adhesive films. SSA shows superior biocompatibility in in vitro cell culture experiments. High pull-off stresses in the range of 3 N cm−2 on a rough surface are achieved, promising broad application spectra for SSA-based healthcare products

    Hydrodynamic object recognition using pressure sensing

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    Hydrodynamic sensing is instrumental to fish and some amphibians. It also represents, for underwater vehicles, an alternative way of sensing the fluid environment when visual and acoustic sensing are limited. To assess the effectiveness of hydrodynamic sensing and gain insight into its capabilities and limitations, we investigated the forward and inverse problem of detection and identification, using the hydrodynamic pressure in the neighbourhood, of a stationary obstacle described using a general shape representation. Based on conformal mapping and a general normalization procedure, our obstacle representation accounts for all specific features of progressive perceptual hydrodynamic imaging reported experimentally. Size, location and shape are encoded separately. The shape representation rests upon an asymptotic series which embodies the progressive character of hydrodynamic imaging through pressure sensing. A dynamic filtering method is used to invert noisy nonlinear pressure signals for the shape parameters. The results highlight the dependence of the sensitivity of hydrodynamic sensing not only on the relative distance to the disturbance but also its bearing