428 research outputs found

    Optimal Control of a Class of Timed Discrete Event Systems with Shared Resources, An Approach Based on the Hadamard Product of Series in Dioids

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    The topic of this paper is modeling and control of timed discrete event systems in a dioid framework if systems operate under the restriction of shared resources. The behavior of such systems can be elegantly modeled using the Hadamard product of series in dioids. Using residuation of the Hadamard product, it is possible to compute optimal control, where optimality is in the sense of a lexicographical order reflecting the chosen prioritization of subsystems. The paper concludes with an example, illustrating the efficiency of the proposed method

    Strategic Renewal: Past Research, Theoretical Tensions and Future Challenges

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    Strategic renewal has become a prominent theme in a variety of organization and management research domains in recent years. It refers to the process that allows organizations to alter their path dependence by transforming their strategic intent and capabilities. With contributions from an increasing range of theoretical perspectives and research contexts, the strategic renewal literature has become fragmented and lacks common definitions and conceptual clarity, which prevent cross-fertilization and harm further development. This study systematically reviews the various literature streams on strategic renewal to provide a more integrative perspective. The authors identify three key theoretical tensions at the heart of strategic renewal research, namely learning vs. resource, induced vs. autonomous, and co-alignment vs. co-creation. By exploring these key tensions, the authors define strategic renewal's conceptual core, identify gaps in the past literature, and provide guidance for future research

    Transport, magnetic, and structural properties of La0.7_{0.7}Ce0.3_{0.3}MnO3_3 thin films. Evidence for hole-doping

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    Cerium-doped manganite thin films were grown epitaxially by pulsed laser deposition at 720720 ^\circC and oxygen pressure pO2=125p_{O_2}=1-25 Pa and were subjected to different annealing steps. According to x-ray diffraction (XRD) data, the formation of CeO2_2 as a secondary phase could be avoided for pO28p_{O_2}\ge 8 Pa. However, transmission electron microscopy shows the presence of CeO2_2 nanoclusters, even in those films which appear to be single phase in XRD. With O2_2 annealing, the metal-to-insulator transition temperature increases, while the saturation magnetization decreases and stays well below the theoretical value for electron-doped La0.7_{0.7}Ce0.3_{0.3}MnO3_3 with mixed Mn3+^{3+}/Mn2+^{2+} valences. The same trend is observed with decreasing film thickness from 100 to 20 nm, indicating a higher oxygen content for thinner films. Hall measurements on a film which shows a metal-to-insulator transition clearly reveal holes as dominating charge carriers. Combining data from x-ray photoemission spectroscopy, for determination of the oxygen content, and x-ray absorption spectroscopy (XAS), for determination of the hole concentration and cation valences, we find that with increasing oxygen content the hole concentration increases and Mn valences are shifted from 2+ to 4+. The dominating Mn valences in the films are Mn3+^{3+} and Mn4+^{4+}, and only a small amount of Mn2+^{2+} ions can be observed by XAS. Mn2+^{2+} and Ce4+^{4+} XAS signals obtained in surface-sensitive total electron yield mode are strongly reduced in the bulk-sensitive fluorescence mode, which indicates hole-doping in the bulk for those films which do show a metal-to-insulator transition.Comment: 8 pages, 10 figure

    Beyond the black box: drug- and device-associated hypersensitivity events

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    Charles L Bennett1,2, Olatokunbo S Adegboro2, Elizabeth A Calhoun2, Dennis Raisch3,41Jesse Brown VA Medical Center, Chicago, IL, USA; 2University of Illinois School of Public Health, Chicago, IL, USA; 3University of New Mexico College of Pharmacy, Albuquerque, NM, USA; 4Veteran Affairs Cooperative Studies Program, Clinical Research Pharmacy, Albuquerque, NM, USABackground: Drug- and device-associated hypersensitivity reactions are serious toxicities that can result in respiratory failure or acute cardiac ischemic events, or even severe hypersensitivity syndromes such as Stevens–Johnson syndrome. These toxicities are usually poorly described in the “black box” warnings section of the product labels.Methods: Adverse event reports contained in databases maintained by the Project on Medical Research on Adverse Drug Events and Reports (Med-RADAR), product labels, safety advisories disseminated by pharmaceutical manufacturers, the Food and Drug Administration (FDA), and the Centers for Disease Control and Prevention (CDC) were reviewed.Results: Adverse event reports identified three health care workers who developed nevirapineassociated Stevens–Johnson syndrome following occupational exposure to HIV-infected blood or blood products; four persons with localized hypersensitivity and fatal cardiac events associated with rapamycin- or paclitaxel-coated coronary artery stent placements; and six persons with breast cancer who developed severe or fatal anaphylaxis after receiving adjuvant chemotherapy with Cremophor-EL containing paclitaxel. Safety advisories from the FDA, CDC, and the relevant pharmaceutical manufacturers were ambiguous in their description in “black box” warning sections of package inserts describing these serious and potentially fatal toxicities. Conclusion: Improvements are needed in pharmacovigilance and subsequent dissemination of safety advisories for drug/device-associated hypersensitivity reactions.Keywords: adverse events, hypersensivity, toxicity, dru

    YBa2_2Cu3_3O7_7/La0.7_{0.7}Ca0.3_{0.3}MnO3_3 bilayers: Interface coupling and electric transport properties

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    Heteroepitaxially grown bilayers of ferromagnetic La0.7_{0.7}Ca0.3_{0.3}MnO3_3 (LCMO) on top of superconducting YBa2_2Cu3_3O7_7 (YBCO) thin films were investigated by focusing on electric transport properties as well as on magnetism and orbital occupation at the interface. Transport measurements on YBCO single layers and on YBCO/LCMO bilayers, with different YBCO thickness dYd_Y and constant LCMO thickness dL=50d_L=50\,nm, show a significant reduction of the superconducting transition temperature TcT_c only for dY<10d_Y<10\,nm,with only a slightly stronger TcT_c suppression in the bilayers, as compared to the single layers. X-ray magnetic circular dichroism (XMCD) measurements confirm recently published data of an induced magnetic moment on the interfacial Cu by the ferromagnetically ordered Mn ions, with antiparallel alignment between Cu and Mn moments. However, we observe a significantely larger Cu moment than previously reported, indicating stronger coupling between Cu and Mn at the interface. This in turn could result in an interface with lower transparency, and hence smaller spin diffusion length, that would explain our electric transport data, i.e.smaller TcT_c suppression. Moreover, linear dichroism measurements did not show any evidence for orbital reconstruction at the interface, indicating that a large change in orbital occupancies through hybridization is not necessary to induce a measurable ferromagnetic moment on the Cu atoms.Comment: 8 Figure

    Business growth, the internet and risk management in the computer games industry

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    According to Wasserman (2011) the growth of the Internet has transformed the software industry in a wide variety of ways. These include the creation of new business opportunities as well as significant impacts across software business processes such as software development, distribution and product support. This chapter examines one significant sub-sector of the software industry, the computer (or video) games industry, and focuses on the impact on games development companies of the opportunities created by developments in Internet and mobile technologies
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