2,475 research outputs found

    Firm development as an integrated process: with evidence from the General Motors-Fisher Body case

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    This paper argues that an adequate approach to the firm should be able to accommodate the complexities of actual firm development. The latter is conceptualized in terms of three general stages: prime movers or drivers of change, change processes, and change attractors. Furthermore, any "real-world" firm is both a technical and an institutional unit. To emphasize the importance of "real firm" analysis, the discussion presented here revolves around an understanding of the much considered case of General Motors and Fisher Body integration has developed over time. Generalization from this case suggests that an integrated view of the firm is necessary that combines the three stages and the two bases (technical and institutional). Six general perspectives on the firm are identified as having technical or institutional bases that are relevant in each of the three stages. This integrated approach to the firm is explored in terms of the general topic of firm development. It is concluded that, without an integrated approach to firm development, a potentially biased or incomplete analysis can result

    Sequential Voting Promotes Collective Discovery in Social Recommendation Systems

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    One goal of online social recommendation systems is to harness the wisdom of crowds in order to identify high quality content. Yet the sequential voting mechanisms that are commonly used by these systems are at odds with existing theoretical and empirical literature on optimal aggregation. This literature suggests that sequential voting will promote herding---the tendency for individuals to copy the decisions of others around them---and hence lead to suboptimal content recommendation. Is there a problem with our practice, or a problem with our theory? Previous attempts at answering this question have been limited by a lack of objective measurements of content quality. Quality is typically defined endogenously as the popularity of content in absence of social influence. The flaw of this metric is its presupposition that the preferences of the crowd are aligned with underlying quality. Domains in which content quality can be defined exogenously and measured objectively are thus needed in order to better assess the design choices of social recommendation systems. In this work, we look to the domain of education, where content quality can be measured via how well students are able to learn from the material presented to them. Through a behavioral experiment involving a simulated massive open online course (MOOC) run on Amazon Mechanical Turk, we show that sequential voting systems can surface better content than systems that elicit independent votes.Comment: To be published in the 10th International AAAI Conference on Web and Social Media (ICWSM) 201

    Modeling Human Ad Hoc Coordination

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    Whether in groups of humans or groups of computer agents, collaboration is most effective between individuals who have the ability to coordinate on a joint strategy for collective action. However, in general a rational actor will only intend to coordinate if that actor believes the other group members have the same intention. This circular dependence makes rational coordination difficult in uncertain environments if communication between actors is unreliable and no prior agreements have been made. An important normative question with regard to coordination in these ad hoc settings is therefore how one can come to believe that other actors will coordinate, and with regard to systems involving humans, an important empirical question is how humans arrive at these expectations. We introduce an exact algorithm for computing the infinitely recursive hierarchy of graded beliefs required for rational coordination in uncertain environments, and we introduce a novel mechanism for multiagent coordination that uses it. Our algorithm is valid in any environment with a finite state space, and extensions to certain countably infinite state spaces are likely possible. We test our mechanism for multiagent coordination as a model for human decisions in a simple coordination game using existing experimental data. We then explore via simulations whether modeling humans in this way may improve human-agent collaboration.Comment: AAAI 201

    Multiple Scattering of Electromagnetic Waves by an Array of Parallel Gyrotropic Rods

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    We study multiple scattering of electromagnetic waves by an array of parallel gyrotropic circular rods and show that such an array can exhibit fairly unusual scattering properties and provide, under certain conditions, a giant enhancement of the scattered field. Among the scattering patterns of such an array at its resonant frequencies, the most amazing is the distribution of the total field in the form of a perfect self-similar structure of chessboard type. The scattering characteristics of the array are found to be essentially determined by the resonant properties of its gyrotropic elements and cannot be realized for arrays of nongyrotropic rods. It is expected that the results obtained can lead to a wide variety of practical applications.Comment: 5 pages, 6 figure

    Geotraceability: an innovative concept to enhance conventional traceability in the agri-food chain

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    With the globalization of trade, people have become enlightened and demanding consumers as regards the origin of their food and the environment in which it is produced. The concept of geotraceability described in this article responds to that requirement by combining geographical information with conventional traceability data. The inclusion of geographical information relating to the environment of the production plots is based not only on exploiting some functionalities of spatial analysis tools that exist in geographical information systems (GIS) but also on developing specific tools such as a geoidentifier and geoindicators. This article also describes the characteristics and methods of implementing a geographical information management system linked with traceability information. Lastly, the potential for using geotraceability systems in supply chains is analyzed, in particular for consumer warnings in cases of food crisis and assistance for certification of differentiated quality agricultural products

    Longitudinal phase space manipulation in energy recovering linac-driven free-electron lasers

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    Energy recovering an electron beam after it has participated in a free-electron laser (FEL) interaction can be quite challenging because of the substantial FEL-induced energy spread and the energy anti-damping that occurs during deceleration. In the Jefferson Lab infrared FEL driver-accelerator, such an energy recovery scheme was implemented by properly matching the longitudinal phase space throughout the recirculation transport by employing the so-called energy compression scheme. In the present paper,after presenting a single-particle dynamics approach of the method used to energy-recover the electron beam, we report on experimental validation of the method obtained by measurements of the so-called "compression efficiency" and "momentum compaction" lattice transfer maps at different locations in the recirculation transport line. We also compare these measurements with numerical tracking simulations.Comment: 31 pages, 13 figures, submitted to Phys. Rev. Special Topics A&

    Perfluoroalkylated amphiphiles with a morpholinophosphate or a dimorpholinophosphate polar head group

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    Some previously synthesized (perfluoroalkyl)alkyldimorpholinophosphates, CnF2n+1CmH2mOP(O)-[N(CH2CH2)(2)O](2), were found remarkably to stabilize heat sterilizable water-in-fluorocarbon reverse emulsions and to have a strong proclivity to self-aggregate into microtubular assemblies when dispersed in water. This series has now been extended in order to allow structure-property relationships to be established and product optimization to be achieved. A new series of even more fluorophilic compounds consisting in bis[(perfluoroalkyl)alkyl]monomorpholinophosphates, (CnF2n+1CmH2mO)(2)P(O)N(CH2CH2)(2)O, was also synthesized. Preliminary surfactant activity and biocompatibility data are presented and compared to data obtained with non-fluorinated analogues

    Evaluation des Nationalen Programms Ernährung und Bewegung 2008–2012 [Evaluation NPEB 2008-2012]

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    Le PNAAP 2008–2012 définit la stratégie nationale pour la promotion d’une alimentation équilibrée et d'une activité physique suffisante. Le 18 juin 2008, le Conseil fédéral adoptait le programme et chargeait le DFI de sa mise en pratique. Ce programme définit des objectifs à long terme ainsi que des champs d’action prioritaires pour la marche à suivre au plan national ; c’est aussi sur ce programme que se base la collaboration des différents acteurs impliqués. Sa mise en œuvre a été confiée à l’Office fédéral de la santé publique (OFSP), en collaboration avec l’Office fédéral du sport (OFSPO) et en coordination avec les cantons et Promotion Santé Suisse (PSS). Le PNAAP a une vision: motiver la population et plus particulièrement les jeunes à se nourrir de manière équilibrée et à bouger suffisamment, car ces mesures sont à même de lutter efficacement contre la surcharge pondérale, l’obésité, les troubles du comportement alimentaire et les maladies non transmissibles qui y sont liées. Le programme a cinq objectifs: 1. Assurer la coordination nationale 2. Promouvoir une alimentation équilibrée 3. Promouvoir l’activité physique et le sport 4. Réaliser des modèles intégrés de promotion d’un poids corporel sain 5. Optimiser le conseil et la thérapi

    Thomson and Compton scattering with an intense laser pulse

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    Our paper concerns the scattering of intense laser radiation on free electrons and it is focused on the relation between nonlinear Compton and nonlinear Thomson scattering. The analysis is performed for a laser field modeled by an ideal pulse with a finite duration, a fixed direction of propagation and indefinitely extended in the plane perpendicular to it. We derive the classical limit of the quantum spectral and angular distribution of the emitted radiation, for an arbitrary polarization of the laser pulse. We also rederive our result directly, in the framework of classical electrodynamics, obtaining, at the same time, the distribution for the emitted radiation with a well defined polarization. The results reduce to those established by Krafft et al. [Phys. Rev. E 72, 056502 (2005)] in the particular case of linear polarization of the pulse, orthogonal to the initial electron momentum. Conditions in which the differences between classical and quantum results are visible are discussed and illustrated by graphs

    Spin states of asteroids in the Eos collisional family

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    Eos family was created during a catastrophic impact about 1.3 Gyr ago. Rotation states of individual family members contain information about the history of the whole population. We aim to increase the number of asteroid shape models and rotation states within the Eos collision family, as well as to revise previously published shape models from the literature. Such results can be used to constrain theoretical collisional and evolution models of the family, or to estimate other physical parameters by a thermophysical modeling of the thermal infrared data. We use all available disk-integrated optical data (i.e., classical dense-in-time photometry obtained from public databases and through a large collaboration network as well as sparse-in-time individual measurements from a few sky surveys) as input for the convex inversion method, and derive 3D shape models of asteroids together with their rotation periods and orientations of rotation axes. We present updated shape models for 15 asteroids and new shape model determinations for 16 asteroids. Together with the already published models from the publicly available DAMIT database, we compiled a sample of 56 Eos family members with known shape models that we used in our analysis of physical properties within the family. Rotation states of asteroids smaller than ~20 km are heavily influenced by the YORP effect, whilst the large objects more or less retained their rotation state properties since the family creation. Moreover, we also present a shape model and bulk density of asteroid (423) Diotima, an interloper in the Eos family, based on the disk-resolved data obtained by the Near InfraRed Camera (Nirc2) mounted on the W.M. Keck II telescope.Comment: Accepted for publication in ICARUS Special Issue - Asteroids: Origin, Evolution & Characterizatio
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