2,346 research outputs found

    Free cash flow, agency costs, and the affordability method of advertising budgeting

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    This is the published version. Copyright 2002 by the American Marketing Association.The allocation of excess cash has long been recognized in the finance literature as an important aspect of the basic agency conflict between managers and owners. In the advertising budgeting context, marketing scholars report that firms possessing high levels of cash tend to spend more on advertising than what seems necessary or desirable. Indeed, this positive link between excess cash and advertising expenditures constitutes a part of what is commonly referred to as the affordability method of advertising budgeting. Surprisingly, there has been little research that attempts to view this association as a manifestation of agency costs. Therefore, this article examines whether agency costs, as measured by managerial ownership, moderate the relationship between excess cash and advertising expenditures. On the basis of received theory, the authors conceptualize that agency costs will first decrease, then increase, and then decrease again with the level of managerial ownership

    Practical issues and some lessons learned from realization of phase sensitive parametric regenerators

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    Practical issues in pump phase synchronization necessary for coherent all-optical processing are discussed, including feed-forward carrier recovery of phase encoded signals

    Correlating low energy impact damage with changes in modal parameters: a preliminary study on composite beams

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    This paper is an experimental study of the effects of multi-site damage on the vibration response of a composite beam damaged by low energy impact. The variation of the modal parameters with different levels of impact energy and density of impact is studied. Specimens are impacted symmetrically in order to induce a global rate of damage. A damage detection tool Damage Index is introduced in order to verify the estimation of damping ratios. Design of Experiments is used to establish the sensitivity of both energy of impact and density of damage. The DOE analysis results (using natural frequency only) indicate that impact energy for 2nd, 3rd and 4th bending modes is the most significant factor contributing to the changes in the modal parameters for this kind of symmetrical dynamic test

    Type Ibc supernovae in disturbed galaxies: evidence for a top-heavy IMF

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    We compare the radial locations of 178 core-collapse supernovae to the R-band and H alpha light distributions of their host galaxies. When the galaxies are split into `disturbed' and `undisturbed' categories, a striking difference emerges. The disturbed galaxies have a central excess of core-collapse supernovae, and this excess is almost completely dominated by supernovae of types Ib, Ic and Ib/c, whereas type II supernovae dominate in all other environments. The difference cannot easily be explained by metallicity or extinction effects, and thus we propose that this is direct evidence for a stellar initial mass function that is strongly weighted towards high mass stars, specifically in the central regions of disturbed galaxies.Comment: 22 pages, 5 figures, accepted for publication in Ap

    Comparing Simulations of AGN Feedback

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    We perform adaptive mesh refinement (AMR) and smoothed particle hydrodynamics (SPH) cosmological zoom simulations of a region around a forming galaxy cluster, comparing the ability of the methods to handle successively more complex baryonic physics. In the simplest, non-radiative case, the two methods are in good agreement with each other, but the SPH simulations generate central cores with slightly lower entropies and virial shocks at slightly larger radii, consistent with what has been seen in previous studies. The inclusion of radiative cooling, star formation, and stellar feedback leads to much larger differences between the two methods. Most dramatically, at z=5, rapid cooling in the AMR case moves the accretion shock well within the virial radius, while this shock remains near the virial radius in the SPH case, due to excess heating, coupled with poorer capturing of the shock width. On the other hand, the addition of feedback from active galactic nuclei (AGN) to the simulations results in much better agreement between the methods. In this case both simulations display halo gas entropies of 100 keV cm^2, similar decrements in the star-formation rate, and a drop in the halo baryon content of roughly 30%. This is consistent with AGN growth being self-regulated, regardless of the numerical method. However, the simulations with AGN feedback continue to differ in aspects that are not self-regulated, such that in SPH a larger volume of gas is impacted by feedback, and the cluster still has a lower entropy central core.Comment: 22 pages, 20 figures, 3 tables, Accepted to ApJ, comments welcom

    Field-trial of an all-optical PSK regenerator/multicaster in a 40 Gbit/s, 38 channel DWDM transmission experiment

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    The performance of future ultra-long haul communication systems exploiting phase-encoded signals is likely to be compromised by noise generated during signal transmission. One potential way to mitigate such noise is to use Phase Sensitive Amplifiers (PSAs) which have been demonstrated to help remove phase as well as amplitude noise from phase-encoded signals. Recently, we showed that a PSA-based signal regenerator based on degenerate four-wave mixing can be implemented in a network-compatible manner in which only the (noisy) signal is present at the device input (black-box operation). The developed regenerator was also able to perform simultaneous wavelength conversion and multicasting, details/analysis of which are presented herein. However, this scheme was tested only with artificial noise generated in the laboratory and with the regenerator placed in front of the receiver, rather than in-line where even greater performance benefits are to be expected. Here, we address both theoretically and experimentally the important issue of how such a regenerator, operating for convenience in a multicasting mode, performs as an in-line device in an installed transmission fiber link. We also investigate the dispersion tolerance of the approach

    Packet compression of complex modulation formats based on coherent optical superposition

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    We propose and numerically demonstrate a packet compression scheme based on re-coding of complex modulation formats through the use of a delay line interferometer (DLI) followed by a temporal gate. A variety of modulation formats can be accommodated and high compression factors can be obtained by using multiple DLIs to achieve higher order modulation formats

    Robust design of all-optical PSK regenerator based on phase sensitive amplification

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    More compact, stable, and efficient configuration of a recently-developed regenerator is presented. The regenerator is assessed at data rates up to 56 Gbit/s using white phase noise for the first time

    Contributors to the March Issue/Notes

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    Notes by Robert E. Richardson, Bernard F. Grainey, Leo L. Linck, Joseph J. Miller, Jr., James E. Diver, William B. Mooney, John M. Speca, Timothy M. Green, and Daniel D. Dahill

    Simultaneous single-molecule measurements of phage T7 replisome composition and function reveal the mechanism of polymerase exchange

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    A complete understanding of the molecular mechanisms underlying the functioning of large, multiprotein complexes requires experimental tools capable of simultaneously visualizing molecular architecture and enzymatic activity in real time. We developed a novel single-molecule assay that combines the flow-stretching of individual DNA molecules to measure the activity of the DNA-replication machinery with the visualization of fluorescently labeled DNA polymerases at the replication fork. By correlating polymerase stoichiometry with DNA synthesis of T7 bacteriophage replisomes, we are able to quantitatively describe the mechanism of polymerase exchange. We find that even at relatively modest polymerase concentration (~2 nM), soluble polymerases are recruited to an actively synthesizing replisome, dramatically increasing local polymerase concentration. These excess polymerases remain passively associated with the replisome through electrostatic interactions with the T7 helicase for ~50 s until a stochastic and transient dissociation of the synthesizing polymerase from the primer-template allows for a polymerase exchange event to occur
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