446 research outputs found

    Innovation networks: problems and prospects (Russian case study)

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    The topologies of innovation network development in Russia are described in this article. Study was conductedin one of the Russian industrial leader JSC Academician M.F. Reshetnev "Information Satellite Systems". Theoretical approaches to the network nature and classification are revealed herein. Some characteristics of innovation network as relatedness, centrality, and intensity were discussed in the article."Information Satellite Systems" has a lot of branch and subsidiaries which form the innovation network of this enterprise. Research methodology consists of head of companies' survey and interview and analyses of open information of firm functioning. Results of research show the vertical hierarchaloriented innovation network with a low-degree of relatedness. Also anchor company ISS has a distinct network landscape with a focus on large vertically integrated, with a low degree of network connectivity, with the unexpressed (weak) links, where a key type of partnership is scientific collaboration with the base (dependent) subsidiary companies, universities and research institutes

    Lehmann-Symanzik-Zimmermann S-Matrix elements on the Moyal Plane

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    Field theories on the Groenewold-Moyal(GM) plane are studied using the Lehmann-Symanzik-Zimmermann(LSZ) formalism. The example of real scalar fields is treated in detail. The S-matrix elements in this non-perturbative approach are shown to be equal to the interaction representation S-matrix elements. This is a new non-trivial result: in both cases, the S-operator is independent of the noncommutative deformation parameter ΞΌΜ\theta_{\mu\nu} and the change in scattering amplitudes due to noncommutativity is just a time delay. This result is verified in two different ways. But the off-shell Green's functions do depend on ΞΌΜ\theta_{\mu\nu}. In the course of this analysis, unitarity of the non-perturbative S-matrix is proved as well.Comment: 18 pages, minor corrections, To appear in Phys. Rev. D, 201

    Remote sensing derived phenological metrics to assess the spatio-temporal growth variability in cropping fields

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    Precision Agriculture (PA) recognizes and manages intra-field spatial variability to increase profitability and reduced environmental impact. Site Specific Crop Management (SSCM), a form of PA, subdivides a cropping field into uniformly manageable zones, based on quantitative measurement of yield limiting factors. In Mediterranean environments, the spatial and temporal yield variability of rain-fed cropping system is strongly influenced by the spatial variability of Plant Available Water-holding Capacity (PAWC) and its strong interaction with temporally variable seasonal rainfall. The successful adoption of SSCM depends on the understanding of both spatial and temporal variabilities in cropping fields. Remote sensing phenological metrics provide information about the biophysical growth conditions of crops across fields. In this paper, we examine the potential of phenological metrics to assess the spatial and temporal crop growth variability across a cropping field. The study was conducted at a wheat cropping field in Minnipa, South Australia. The field was classified into three management zones using prolonged observations including soil assessment and multiple year yield data. The main analytical steps followed in this study were: calculation of the phenological metrics using time series NDVI data from Moderate Resolution Imaging Spectroradiometer (MODIS) for 15 years (2001-2015); producing spatial trend and temporal variability maps of phenological metrics; and finally, assessment of association between the spatial patterns and temporal variability of the metrics with management zones of the cropping field. The spatial trend of the seasonal peak NDVI metric showed significant association with the management zone pattern. In terms of temporal variability, Time-integrated NDVI (TINDVI) showed higher variability in the "good" zone compared with the "poor" zone. This indicates that the magnitude of the seasonal peak is moresensitive to soil related factors across the field, whereas TINDVI is more sensitive to seasonal variability. The interpretation of the association between phenological metrics and the management zone site conditions was discussed in relation to soil-climate interaction. The results demonstrate the potential of the phenological metrics to assess the spatial and temporal growth variability across cropping fields and to understand the soil-climate interaction. The approach presented in this paper provides a pathway to utilize phenological metrics for precision agricultural management application.Sofanit Araya, Bertram Ostendorf, Greg Lyle, Megan Lewi

    Thermal bremsstrahlung probing the thermodynamical state of multifragmenting systems

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    Inclusive and exclusive hard-photon (EÎł>_\gamma > 30 MeV) production in five different heavy-ion reactions (36^{36}Ar+197^{197}Au, 107^{107}Ag, 58^{58}Ni, 12^{12}C at 60{\it A} MeV and 129^{129}Xe+120^{120}Sn at 50{\it A} MeV) has been studied coupling the TAPS photon spectrometer with several charged-particle multidetectors covering more than 80% of 4π\pi. The measured spectra, slope parameters and source velocities as well as their target-dependence, confirm the existence of thermal bremsstrahlung emission from secondary nucleon-nucleon collisions that accounts for roughly 20% of the total hard-photon yield. The thermal slopes are a direct measure of the temperature of the excited nuclear systems produced during the reaction.Comment: 4 pages, 3 figures, Proceedings CRIS 2000, 3rd Catania Relativistic Ion Studies, "Phase Transitions in Strong Interactions: Status and Perspectives", Acicastello, Italy, May 22-26, 2000 (to be published in Nuc. Phys. A

    Comparative analysis of quantum cascade laser modeling based on density matrices and non-equilibrium Green's functions

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    We study the operation of an 8.5 mu m quantum cascade laser based on GaInAs/AlInAs lattice matched to InP using three different simulation models based on density matrix (DM) and non-equilibrium Green's function (NEGF) formulations. The latter advanced scheme serves as a validation for the simpler DM schemes and, at the same time, provides additional insight, such as the temperatures of the sub-band carrier distributions. We find that for the particular quantum cascade laser studied here, the behavior is well described by simple quantum mechanical estimates based on Fermi's golden rule. As a consequence, the DM model, which includes second order currents, agrees well with the NEGF results. Both these simulations are in accordance with previously reported data and a second regrown device. (C) 2014 AIP Publishing LLC

    Evidence for Thermal Equilibration in Multifragmentation Reactions probed with Bremsstrahlung Photons

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    The production of nuclear bremsstrahlung photons (EÎł>_{\gamma}> 30 MeV) has been studied in inclusive and exclusive measurements in four heavy-ion reactions at 60{\it A} MeV. The measured photon spectra, angular distributions and multiplicities indicate that a significant part of the hard-photons are emitted in secondary nucleon-nucleon collisions from a thermally equilibrated system. The observation of the thermal component in multi-fragment 36^{36}Ar+197^{197}Au reactions suggests that the breakup of the thermalized source produced in this system occurs on a rather long time-scale.Comment: Revised version, accepted for publication in Physical Review Letters. 4 pages, 4 fig

    Hard photon and neutral pion production in cold nuclear matter

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    The production of hard photons and neutral pions in 190 MeV proton induced reactions on C, Ca, Ni, and W targets has been for the first time concurrently studied. Angular distributions and energy spectra up to the kinematical limit are discussed and the production cross-sections are presented. From the target mass dependence of the cross-sections the propagation of pions through nuclear matter is analyzed and the production mechanisms of hard photons and primordial pions are derived. It is found that the production of subthreshold particles proceeds mainly through first chance nucleon-nucleon collisions. For the most energetic particles the mass scaling evidences the effect of multiple collisions.Comment: submitted to Phys. Lett.

    Deterministic delivery of externally cold and precisely positioned single molecular ions

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    We present the preparation and deterministic delivery of a selectable number of externally cold molecular ions. A laser cooled ensemble of Mg^+ ions subsequently confined in several linear Paul traps inter-connected via a quadrupole guide serves as a cold bath for a single or up to a few hundred molecular ions. Sympathetic cooling embeds the molecular ions in the crystalline structure. MgH^+ ions, that serve as a model system for a large variety of other possible molecular ions, are cooled down close to the Doppler limit and are positioned with an accuracy of one micrometer. After the production process, severely compromising the vacuum conditions, the molecular ion is efficiently transfered into nearly background-free environment. The transfer of a molecular ion between different traps as well as the control of the molecular ions in the traps is demonstrated. Schemes, optimized for the transfer of a specific number of ions, are realized and their efficiencies are evaluated. This versatile source applicable for broad charge-to-mass ratios of externally cold and precisely positioned molecular ions can serve as a container-free target preparation device well suited for diffraction or spectroscopic measurements on individual molecular ions at high repetition rates (kHz).Comment: 11 pages, 8 figure

    Infra-Red Asymptotic Dynamics of Gauge Invariant Charged Fields: QED versus QCD

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    The freedom one has in constructing locally gauge invariant charged fields in gauge theories is analyzed in full detail and exploited to construct, in QED, an electron field whose two-point function W(p), up to the fourth order in the coupling constant, is normalized with on-shell normalization conditions and is, nonetheless, infra-red finite; as a consequence the radiative corrections vanish on the mass shell p2=Ό2p^2=\mu^2 and the free field singularity is dominant, although, in contrast to quantum field theories with mass gap, the eigenvalue Ό2\mu^2 of the mass operator is not isolated. The same construction, carried out for the quark in QCD, is not sufficient for cancellation of infra-red divergences to take place in the fourth order. The latter divergences, however, satisfy a simple factorization equation. We speculate on the scenario that could be drawn about infra-red asymptotic dynamics of QCD, should this factorization equation be true in any order of perturbation theory.Comment: 30 pages, RevTex, 8 figures included using graphic
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