5,071 research outputs found

    Marketing Percolation

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    A percolation model is presented, with computer simulations for illustrations, to show how the sales of a new product may penetrate the consumer market. We review the traditional approach in the marketing literature, which is based on differential or difference equations similar to the logistic equation (Bass 1969). This mean field approach is contrasted with the discrete percolation on a lattice, with simulations of "social percolation" (Solomon et al 2000) in two to five dimensions giving power laws instead of exponential growth, and strong fluctuations right at the percolation threshold.Comment: to appear in Physica

    An absorption spectrum amplifier for determining gas composition

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    Compositions of gas samples are frequently studied by laser absorption spectroscopy. Sensitivity is improved by two orders of magnitude when absorption cell is placed inside an organic-dye laser cavity

    Generalized Robba rings

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    We prove that any projective coadmissible module over the locally analytic distribution algebra of a compact pp-adic Lie group is finitely generated. In particular, the category of coadmissible modules does not have enough projectives. In the Appendix a "generalized Robba ring" for uniform pro-pp groups is constructed which naturally contains the locally analytic distribution algebra as a subring. The construction uses the theory of generalized microlocalization of quasi-abelian normed algebras that is also developed there. We equip this generalized Robba ring with a self-dual locally convex topology extending the topology on the distribution algebra. This is used to show some results on coadmissible modules.Comment: with an appendix by Peter Schneider; revised; new titl

    Spin transfer and current-induced switching in antiferromagnets

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    We present theoretical description of the precessional switching processes induced by simultaneous application of spin-polarized current and external magnetic field to antiferromagnetic component of the "pinned" layer. We found stability ranges of different static and dynamic regimes. We showed the possibility of steady current-induced precession of antiferromagnetic vector with frequency that linearly depends on the bias current. Furthermore, we found an optimal duration of current pulse required for switching between different orientations of antiferromagnetic vector and current and field dependence of switching time. Our results reveal the difference between dynamics of ferro- and antiferromagnets subjected to spin transfer torques.Comment: 7 pages, 4 figure

    Sensitivity of Ag/Al Interface Specific Resistances to Interfacial Intermixing

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    We have measured an Ag/Al interface specific resistance, 2AR(Ag/Al)(111) = 1.4 fOhm-m^2, that is twice that predicted for a perfect interface, 50% larger than for a 2 ML 50%-50% alloy, and even larger than our newly predicted 1.3 fOhmm^2 for a 4 ML 50%-50% alloy. Such a large value of 2ARAg/Al(111) confirms a predicted sensitivity to interfacial disorder and suggests an interface greater than or equal to 4 ML thick. From our calculations, a predicted anisotropy ratio, 2AR(Ag/Al)(001)/2AR(Ag/Al)(111), of more then 4 for a perfect interface, should be reduced to less than 2 for a 4 ML interface, making it harder to detect any such anisotropy.Comment: 3 pages, 2 figures, 1 table. In Press: Journal of Applied Physic

    Beat-wave generation of plasmons in semiconductor plasmas

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    It is shown that in semiconductor plasmas, it is possible to generate large amplitude plasma waves by the beating of two laser beams with frequency difference close to the plasma frequency. For narrow gap semiconductors (for example n-type InSb), the system can simulate the physics underlying beat wave generation in relativistic gaseous plasmas.Comment: 11 pages, LaTex, no figures, no macro

    Applications of aerospace technology in biology and medicine

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    Utilization of National Aeronautics and Space Administration (NASA) technology in medicine is discussed. The objective is best obtained by stimulation of the introduction of new or improved commercially available medical products incorporating aerospace technology. A bipolar donor/recipient model of medical technology transfer is presented to provide a basis for the team's methodology. That methodology is designed to: (1) identify medical problems and NASA technology that, in combination, constitute opportunities for successful medical products; (2) obtain the early participation of industry in the transfer process; and (3) obtain acceptance by the medical community of new medical products based on NASA technology. Two commercial transfers were completed: the Stowaway, a lightweight wheelchair that provides mobility for the disabled and elderly in the cabin of commercial aircraft, and Micromed, a portable medication infusion pump for the reliable, continuous infusion of medications such as heparin or insulin. The marketing and manufacturing factors critical to the commercialization of the lightweight walker incorporating composite materials were studied. Progress was made in the development and commercialization of each of the 18 currently active projects

    Scrum for product innovation : a longitudinal embedded case study

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    This article describes the innovation processes used in a partnership between Add Latent Ltd., an asset integrity and maintenance management consulting services provider in the energy sector and University of Salford. The challenge faced by the company is to make their in-house expertise more readily available to a worldwide audience. A longitudinal embedded case study has been used to investigate how installable desktop software applications have been redesigned to create a new set of cloud hosted software services. The innovation team adapted an agile scrum process to include exploratory prototyping and manage the geographical distribution of the team members. A minimum viable product was developed that integrated functional elements of previous software tools into an end-to-end data collection, analysis and visualisation product called AimHi which uses a cloud-hosted web services approach. Field trials were conducted using the software at the Uniper, Isle of Grain power station in Kent, UK. Enhancements were made to the AimHi product which was adopted for use at the Uniper site. The product emerged from a Knwledge Transfer Partnership whci was evaluated on cmplettion by InnovateUK and awarded the highest possible “outstanding” grade. The article illustrates how the scrum software development method was tailored for a product innovation context. Extended periods of evaluation and reflection, prototyping and requirement refinement were combined with periods of incremental feature development using sprints. The AimHi product emerged from a technology transfer and innovation project that has successfully reconciled conflicting demands from customers, universities, partner companies and project staff members

    Enhanced Event-by-Event Fluctuations in Pion Multiplicity as a Signal of Disoriented Chiral Condensates at RHIC

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    The factorial moments of the pion multiplicity distributions are calculated with HIJING and UrQMD and found to be independent of the pT range included, in contrast to recent simulations with the linear sigma model which leads to large enhancements for pions with transverse kinetic energies below 200 MeV. This supports the use of the ratio of the factorial moments of low and high pT pions as a signal of ``new'' physics at low momentum scales, such as the formation of disoriented chiral condensates.Comment: 4 pages total, incl 4 eps figures ([email protected]
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