683,801 research outputs found

    Upstream market foreclosure

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    This paper investigates how an incumbent monopolistic can weaken potential rivals or deter entry in the output market by manipulating the access of these rivals in the input market. We analyze two polar cases. In the first one, the input market is assumed to be competitive with the input being supplied inelastically. We show that the situation opens the door to entry deterrence. Then, we assume that the input is supplied by a single seller who chooses the input price. In this case we show that entry deterrence can be reached only through merger with the seller of the input.Entry deterrence, Foreclosure, Overinvestment, Bilateral monopoly

    Effects of Leakage Neutral Particles on Shocks

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    In this paper we investigate effects of neutral particles on shocks propagating into the partially ionized medium. We find that for 120 km/s < u_{sh} < 3000 km/s (u_{sh} is the shock velocity), about ten percent of upstream neutral particles leak into the upstream region from the downstream region. Moreover, we investigate how the leakage neutral particles affect the upstream structure of the shock and particle accelerations. Using four fluid approximations (upstream ions, upstream neutral particles, leakage neutral particles and pickup ions), we provide analytical solutions of the precursor structure due to leakage neutral particles. It is shown that the upstream flow is decelerated in the precursor region and the shock compression ratio becomes smaller than without leakage neutral particles, but the total compression ratio does not change. Even if leakage of neutral particles is small (a few percents of total upstream particles), this smaller compression ratio of the shock can explain steep gamma-ray spectra from young supernova remnants. Furthermore, leakage neutral particles could amplify the magnetic field and heat the upstream region.Comment: 9 pages, 4 figures, accepted for publication in Ap

    Upstream reciprocity in heterogeneous networks

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    Many mechanisms for the emergence and maintenance of altruistic behavior in social dilemma situations have been proposed. Indirect reciprocity is one such mechanism, where other-regarding actions of a player are eventually rewarded by other players with whom the original player has not interacted. The upstream reciprocity (also called generalized indirect reciprocity) is a type of indirect reciprocity and represents the concept that those helped by somebody will help other unspecified players. In spite of the evidence for the enhancement of helping behavior by upstream reciprocity in rats and humans, theoretical support for this mechanism is not strong. In the present study, we numerically investigate upstream reciprocity in heterogeneous contact networks, in which the players generally have different number of neighbors. We show that heterogeneous networks considerably enhance cooperation in a game of upstream reciprocity. In heterogeneous networks, the most generous strategy, by which a player helps a neighbor on being helped and in addition initiates helping behavior, first occupies hubs in a network and then disseminates to other players. The scenario to achieve enhanced altruism resembles that seen in the case of the Prisoner's Dilemma game in heterogeneous networks.Comment: 10 figures, Journal of Theoretical Biology, in press (2010

    The 'upstream wake' of swimming and flying animals and its correlation with propulsive efficiency

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    The interaction between swimming and flying animals and their fluid environments generates downstream wake structures such as vortices. In most studies, the upstream flow in front of the animal is neglected. In this study, we demonstrate the existence of upstream fluid structures even though the upstream flow is quiescent or possesses a uniform incoming velocity. Using a computational model, the flow generated by a swimmer (an oscillating flexible plate) is simulated and a new fluid mechanical analysis is applied to the flow to identify the upstream fluid structures. These upstream structures show the exact portion of fluid that is going to interact with the swimmer. A mass flow rate is then defined based on the upstream structures, and a metric for propulsive efficiency is established using the mass flow rate and the kinematics of the swimmer. We propose that the unsteady mass flow rate defined by the upstream fluid structures can be used as a metric to measure and objectively compare the efficiency of locomotion in water and air

    Whistler mode waves upstream of Saturn

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    Whistler-mode waves are generated within and can propagate upstream of collisionless shocks. They are known to play a role in electron thermodynamics/acceleration and, under certain conditions, are markedly observed as wave trains preceding the shock ramp. In this paper, we take advantage of Cassini's presence at ~10 AU to explore the importance of whistler-mode waves in a parameter regime typically characterized by higher Mach number (median of ~14) shocks, as well as a significantly different IMF structure, compared to near Earth. We identify electromagnetic precursors preceding a small subset of bow shock crossings with properties which are consistent with whistler-mode waves. We find these monochromatic, low-frequency, circularly-polarized waves to have a typical frequency range of 0.2 - 0.4 Hz in the spacecraft frame. This is due to the lower ion and electron cyclotron frequencies near Saturn, between which whistler waves can develop. The waves are also observed as predominantly right-handed in the spacecraft frame, the opposite sense to what is typically observed near Earth. This is attributed to the weaker Doppler shift, owing to the large angle between the solar wind velocity and magnetic field vectors at 10 AU. Our results on the low occurrence of whistler waves upstream of Saturn also underpins the predominantly supercritical bow shock of Saturn.Comment: Published in Journal of Geophysical Research: Space Physics (January 2017) 21 pages, 4 figure

    Anticompetitive vertical mergers waves

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    This paper develops an equilibrium model of vertical mergers. We show that competition on an upstream market between integrated firms only is less intense than in the presence of unintegrated upstream firms. Indeed, when an integrated firm supplies the upstream market, it becomes a soft downstream competitor to preserve its upstream profits. This benefits other integrated firms, which may therefore choose not to cut prices on the upstream market. This mechanism generates waves of vertical mergers in which every upstream firm integrates with a downstream firm, and the remaining unintegrated downstream firms obtain the input at a high upstream price. We show that these anticompetitive vertical mergers waves are more likely when downstream competition is fiercer.

    Upstream horizontal mergers, bargaining, vertical contracts

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    Contrary to the seminal paper of Horn and Wolinsky (1988), we demonstrate that upstream firms, which sell their products to competing downstream firms, do not always have incentives to merge horizontally. In particular, we show that when bargaining takes place over two-part tariffs, and not over wholesale prices, upstream firms prefer to act as independent suppliers rather than as a monopolist supplier. Moreover, we show that horizontal mergers can be procompetitive, even in the absence of efficiency gains
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