Consolidations and the Sequence of Acquisitions to Monopoly

We examine horizontal merger activity between firms which have differing costs. Upon merging owners can transfer technology to an acquired firm and can decide whether to operate their firms as separate entities in the product market or consolidate their acquisitions. Thus, in our analysis, mergers can exhibit both an efficiency effect and a market power effect. The purchase prices of target firms are determined via a bargaining game. We find that the largest firm is likely to be acquisitive and that the optimal sequence of mergers entails targeting the next largest rival firm. We find that not consolidating an acquired firm can reveal the intention to acquire additional firms. The optimal sequence of mergers with technology transfers and no consolidations is found initially to be welfare improving. Ultimately, however, the acquisitions lead to consolidation and a decrease in total welfare. ZUSAMMENFASSUNG - (Konsolidierungen und die Folge von Akquisitionen zum Monopol) In dem Beitrag werden horizontale Unternehmenszusammenschlüsse zwischen Unternehmen mit unterschiedlichen Kosten analysiert. Für das erwerbende Unternehmen stellt sich die Frage, ob es Technologie zu einer erworbenen Firma transferieren sollte und, ob es das erworbene Unternehmen als getrennte Einheit im Produktmarkt betreiben oder mit dem fusionierten Unternehmen zusammen am Markt operieren will. In der Analyse wird der Effizienzeffekt und der Marktmachteffekt berücksichtigt. Der Kaufpreis des zu erwerbenden Unternehmens wird in einem "bargaining game" ermittelt. Im Ergebnis zeigt sich, daß das größte Unternehmen wahrscheinlich das erwerbende sein wird und daß die optimale Reihenfolge von Fusionen sich auf das nächst größte Konkurrenzunternehmen bezieht. Außerdem zeigt sich, daß die Nichtkonsolidierung mit erworbenen Unternehmen daraufhin deutet, daß eine Intention zum Erwerb weiterer Firmen vorliegt. Die optimale Folge von Fusionen mit Technologietransfer und ohne Konsolidierungen erhöht anfangs die Wohlfahrt. Letztlich aber führen die Erwerbungen zur Konsolidierung und zu einem Absinken der Gesamtwohlfahrt.

Random sequential adsorption and diffusion of dimers and k-mers on a square lattice

We have performed extensive simulations of random sequential adsorption and diffusion of $k$-mers, up to $k=5$ in two dimensions with particular attention to the case $k=2$. We focus on the behavior of the coverage and of vacancy dynamics as a function of time. We observe that for $k=2,3$ a complete coverage of the lattice is never reached, because of the existence of frozen configurations that prevent isolated vacancies in the lattice to join. From this result we argue that complete coverage is never attained for any value of $k$. The long time behavior of the coverage is not mean field and nonanalytic, with $t^{-1/2}$ as leading term. Long time coverage regimes are independent of the initial conditions while strongly depend on the diffusion probability and deposition rate and, in particular, different values of these parameters lead to different final values of the coverage. The geometrical complexity of these systems is also highlighted through an investigation of the vacancy population dynamics.Comment: 9 pages, 9 figures, to be published in the Journal of Chemical Physic

Protist predation can favour cooperation within bacterial species

Here, we studied how protist predation affects cooperation in the opportunistic pathogen bacterium Pseudomonas aeruginosa, which uses quorum sensing (QS) cell-to-cell signalling to regulate the production of public goods. By competing wild-type bacteria with QS mutants (cheats), we show that a functioning QS system confers an elevated resistance to predation. Surprisingly, cheats were unable to exploit this resistance in the presence of cooperators, which suggests that resistance does not appear to result from activation of QS-regulated public goods. Instead, elevated resistance of wild-type bacteria was related to the ability to form more predation-resistant biofilms. This could be explained by the expression of QS-regulated resistance traits in densely populated biofilms and floating cell aggregations, or alternatively, by a pleiotropic cost of cheating where less resistant cheats are selectively removed from biofilms. These results show that trophic interactions among species can maintain cooperation within species, and have further implications for P. aeruginosa virulence in environmental reservoirs by potentially enriching the cooperative and highly infective strains with functional QS system

Glassy behaviour in short range lattice models without quenched disorder

We investigate the quenching process in lattice systems with short range interaction and several crystalline states as ground states. We consider in particular the following systems on square lattice: - hard particle (exclusion) model; - q states planar Potts model. The system is initially in a homogeneous disordered phase and relaxes toward a new equilibrium state as soon as the temperature is rapidly lowered. The time evolution can be described numerically by a stochastic process such as the Metropolis algorithm. The number of pure, equivalent, ground states is q for the Potts model and r for the hard particle model, and it is known that for r or q larger or equal to d+1, the final equilibrium state may be polycrystalline, i.e. not made of a uniform phase. We find that in addition n_g and q_g exist such that for r > r_g, or q > q_g the system evolves toward a glassy state, i.e. a state in which the ratio of the interaction energy among the different crystalline phases to the total energy of the system never vanishes; moreover we find indications that r_g=q_g. We infer that q=q_g (and r=r_g) corresponds to the crossing from second order to discontinuous transition in the phase diagram of the system.Comment: 10 pages, 3 figure