13,647 research outputs found
Power in the Multinational Corporation in Industry Equilibrium
Recent theories of the multinational corporation introduce the property rights model of the firm and examine whether to integrate our outsource firm activities locally or to a foreign country. This paper focus instead on the internal organization of the multinational corporation by examining the power allocation between headquarters and subsidiaries. We provide a framework to analyse the interaction between the decision to serve the local market by exporting or FDI, market acces and the optimal mode of organization of the multinational corporation. We find that subsidiary managers are given most autonomy in their decision how to run the firm at intermediate levels of local competition. We then provide comparative statics for changes in fixed FDI entry costs and trade costs, information technology, the number of local competitors, and in the size of the local market
Corporate Hierarchies and the Size of Nations: Theory and Evidence
Corporate organization varies within a country and across countries with country size. The paper starts by establishing some facts about corporate organization based on unique data of 660 Austrian and German corporations. The larger country (Germany) has larger firms with flatter more decentral corporate hierarchies compared to the smaller country (Austria). Firms in the larger country change their organization less fast than firms in the smaller country. Over time firms have been introducing less hierarchical organizations by delegating power to lower levels of the corporation. We develop a theory which explains these facts and which links these features to the trade environment that countries and firms face. We introduce firms with internal hierarchies in a Krugman (1980) model of trade. We show that international trade and the toughness of competition in international markets induce a power struggle in firms which eventually leads to decentralized corporate hierarchies. We offer econometric evidence which is consistent with the models predictions
Reflection nebulae in the Galactic Center: the case for soft X-ray imaging polarimetry
The origin of irradiation and fluorescence of the 6.4 keV bright giant
molecular clouds surrounding Sgr A*, the central supermassive black hole of our
Galaxy, remains enigmatic. Testing the theory of a past active period of Sgr A*
requires X-ray polarimetry. In this paper, we show how modern imaging
polarimeters could revolutionize our understanding of the Galactic Center.
Through Monte Carlo modeling, we produce a 4-8 keV polarization map of the
Galactic Center, focusing on the polarimetric signature produced by Sgr B1, Sgr
B2, G0.11-0.11, Bridge E, Bridge D, Bridge B2, MC2, MC1, Sgr C3, Sgr C2, and
Sgr C1. We estimate the resulting polarization, include polarized flux dilution
by the diffuse plasma emission detected toward the GC, and simulate the
polarization map that modern polarimetric detectors would obtain assuming the
performances of a mission prototype. The eleven reflection nebulae investigated
in this paper present a variety of polarization signatures, ranging from nearly
unpolarized to highly polarized (about 77%) fluxes. A major improvement in our
simulation is the addition of a diffuse, unpolarized plasma emission that
strongly impacts soft X-ray polarized fluxes. The dilution factor is in the
range 50% - 70%, making the observation of the Bridge structure unlikely even
in the context of modern polarimetry. The best targets are the Sgr B and Sgr C
complexes, and the G0.11-0.11 cloud. An exploratory observation of a few
hundred kilo-seconds of the Sgr B complex would allow a significant detection
of the polarization and be sufficient to derive hints on the primary source of
radiation. A more ambitious program (few Ms) of mapping the giant molecular
clouds could then be carried out to probe with great precision the turbulent
history of Sgr A*, and place important constraints on the composition and
three-dimensional position of the surrounding gas.Comment: 7 pages, 3 figures, 2 tables, accepted for publication in A&
Reflection-Free One-Way Edge Modes in a Gyromagnetic Photonic Crystal
We point out that electromagnetic one-way edge modes analogous to quantum
Hall edge states, originally predicted by Raghu and Haldane in 2D gyroelectric
photonic crystals possessing Dirac point-derived bandgaps, can appear in more
general settings. In particular, we show that the TM modes in a gyromagnetic
photonic crystal can be formally mapped to electronic wavefunctions in a
periodic electromagnetic field, so that the only requirement for the existence
of one-way edge modes is that the Chern number for all bands below a gap is
non-zero. In a square-lattice gyromagnetic Yttrium-Iron-Garnet photonic crystal
operating at microwave frequencies, which lacks Dirac points, time-reversal
breaking is strong enough that the effect should be easily observable. For
realistic material parameters, the edge modes occupy a 10% band gap. Numerical
simulations of a one-way waveguide incorporating this crystal show 100%
transmission across strong defects, such as perfect conductors several lattice
constants wide, larger than the width of the waveguide.Comment: 4 pages, 3 figures (Figs. 1 and 2 revised.
Impact of time to appropriate therapy on mortality in patients with vancomycin-intermediate Staphylococcus aureus infection
Despite the increasing incidence of vancomycin-intermediate Staphylococcus aureus (VISA) infections, few studies have examined the impact of delay in receipt of appropriate antimicrobial therapy on outcomes in VISA patients. We examined the effects of timing of appropriate antimicrobial therapy in a cohort of patients with sterile-site methicillin-resistant S. aureus (MRSA) and VISA infections. In this single-center, retrospective cohort study, we identified all patients with MRSA or VISA sterile-site infections from June 2009 to February 2015. Clinical outcomes were compared according to MRSA/VISA classification, demographics, comorbidities, and antimicrobial treatment. Thirty-day all-cause mortality was modeled with Kaplan-Meier curves. Multivariate logistic regression analysis (MVLRA) was used to determine odds ratios for mortality. We identified 354 patients with MRSA (n = 267) or VISA (n = 87) sterile-site infection. Fifty-five patients (15.5%) were nonsurvivors. Factors associated with mortality in MVLRA included pneumonia, unknown source of infection, acute physiology and chronic health evaluation (APACHE) II score, solid-organ malignancy, and admission from skilled care facilities. Time to appropriate antimicrobial therapy was not significantly associated with outcome. Presence of a VISA infection compared to that of a non-VISA S. aureus infection did not result in excess mortality. Linezolid use was a risk for mortality in patients with APACHE II scores of ≥14. Our results suggest that empirical vancomycin use in patients with VISA infections does not result in excess mortality. Future studies should (i) include larger numbers of patients with VISA infections to confirm the findings presented here and (ii) determine the optimal antibiotic therapy for critically ill patients with MRSA and VISA infections
Surmounting collectively oscillating bottlenecks
We study the collective escape dynamics of a chain of coupled, weakly damped
nonlinear oscillators from a metastable state over a barrier when driven by a
thermal heat bath in combination with a weak, globally acting periodic
perturbation. Optimal parameter choices are identified that lead to a drastic
enhancement of escape rates as compared to a pure noise-assisted situation. We
elucidate the speed-up of escape in the driven Langevin dynamics by showing
that the time-periodic external field in combination with the thermal
fluctuations triggers an instability mechanism of the stationary homogeneous
lattice state of the system. Perturbations of the latter provided by incoherent
thermal fluctuations grow because of a parametric resonance, leading to the
formation of spatially localized modes (LMs). Remarkably, the LMs persist in
spite of continuously impacting thermal noise. The average escape time assumes
a distinct minimum by either tuning the coupling strength and/or the driving
frequency. This weak ac-driven assisted escape in turn implies a giant speed of
the activation rate of such thermally driven coupled nonlinear oscillator
chains
Infrared Observations of AGN
We present results from an imaging and spectroscopic study of the dust
properties of Seyfert galaxies in the 1-10um range. The data are compared to
state of the art models of torus emission to constrain geometrical and physical
properties of the obscuring medium.Comment: 2 pages, to appear in the IAU Symp.No.222 proceedings:"The Interplay
among Black Holes, Stars and ISM in Galactic Nuclei", Gramado, Brazil, March
1-5, 200
Parametrização do modelo CANEGRO para as cultivares brasileiras de cana-de-açúcar.
O objetivo do presente trabalho foi a parametrização do modelo CANEGRO para a as cultivares brasileiras IAC 91-1099 e SP 89 1115.Trabalho apresentado na V Mostra de Trabalhos de Estagiários e Bolsistas, Campinas, out. 2009
Plasmon-Emitter Interactions at the Nanoscale
Plasmon-emitter interactions are of paramount importance in modern
nanoplasmonics and are generally maximal at short emitter-surface separations.
However, when the separation falls below 10-20 nm, the classical theory
progressively deteriorates due to its neglect of quantum mechanical effects
such as nonlocality, electronic spill-out, and Landau damping. Here, we show
how this neglect can be remedied by presenting a unified theoretical treatment
of mesoscopic electrodynamics grounded on the framework of Feibelman
-parameters. Crucially, our technique naturally incorporates nonclassical
resonance shifts and surface-enabled Landau damping - a nonlocal damping effect
- which have a dramatic impact on the amplitude and spectral distribution of
plasmon-emitter interactions. We consider a broad array of plasmon-emitter
interactions ranging from dipolar and multipolar spontaneous emission
enhancement, to plasmon-assisted energy transfer and enhancement of two-photon
transitions. The formalism presented here gives a complete account of both
plasmons and plasmon-emitter interactions at the nanoscale, constituting a
simple yet rigorous and general platform to incorporate nonclassical effects in
plasmon-empowered nanophotonic phenomena.Comment: 12 pages, 6 figure
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