Entanglement enhanced information transmission over a quantum channel with correlated noise

We show that entanglement is a useful resource to enhance the mutual information of the depolarizing channel when the noise on consecutive uses of the channel has some partial correlations. We obtain a threshold in the degree of memory, depending on the shrinking factor of the channel, above which a higher amount of classical information is transmitted with entangled signals

A Simple Theory of Predation

We propose a simple theory of predatory pricing, based on scale economies and sequential buyers (or markets). The entrant (or prey) needs to reach a critical scale to be successful. The incumbent (or predator) is ready to make losses on earlier buyers so as to deprive the prey of the scale it needs, thus making monopoly profits on later buyers. Several extensions are considered, including markets where scale economies exist because of demand externalities or two-sided market effects, and where markets are characterised by common costs. Conditions under which predation may take place in actual cases are also discussed.Anticompetitive Behaviour, Exclusion, Below-Cost Pricing, Antitrust

A Simple Theory of Predation

We propose a simple theory of predatory pricing, based on incumbency advantages, scale economies and sequential buyers (or markets). The prey needs to reach a critical scale to be successful. The incumbent (or predator) has an initial advantage and is ready to make losses on earlier buyers so as to deprive the prey of the scale the latter needs, thus making monopoly profits on later buyers. Several extensions are considered, including cases where scale economies exist because of demand externalities or two-sided market effects, and where markets are characterized by common costs. Conditions under which predation may take place in actual cases are also discussed.

Buyers’ miscoordination, entry, and downstream competition

This paper shows that buyers’ coordination failures might prevent entry in an industry with an incumbent firm and a more efficient potential entrant. If there was a single buyer, or if all buyers formed a central purchasing agency, coordination failures would be avoided and efficient entry would always occur. More generally, exclusion is the less likely the lower the number of buyers. For any given number of buyers, exclusion is the less likely the more fiercely buyers compete in the downstream market. First, intense competition may prevent miscoordination equilibria from arising; second, in cases where miscoordination equilibria still exist, it lowers the maximum price that the incumbent can sustain at such exclusionary equilibriaCountervailing Power; Exclusion; Buyers’ Fragmentation

Exclusive dealing, entry, and mergers

This paper studies a model where exclusive dealing (ED) can both promote investment and foreclose a more efficient supplier. While investment promotion is usually regarded as a pro-competitive effect of ED, our paper shows that it may be the very reason why a contract that forecloses a more efficient supplier is signed. Absent the effect on investment, the contract would not be signed and foreclosure would not be a concern. For this reason, considering potential foreclosure and investment promotion in isolation and then summing them up may not be a suitable approach to assess the net effect of ED. The paper therefore invites a more cautious attitude towards accepting possible investment promotion arguments as a defence for ED.

On the Anticompetitive Effect of Exclusive Dealing when Entry by Merger is Possible

We extend the literature on exclusive dealing, which assumes that entry can occur only by installing new capacity, by allowing the incumbent and the potential entrant to merge. This uncovers new effects. First, exclusive deals can be used to improve the incumbent's bargaining position in the merger negotiation. Second, the incumbent finds it easier to elicit the buyer's acceptance. Third, exclusive dealing, despite allowing the more efficient technology to find its way into the industry, reduces welfare because (i) it may trigger entry through merger whereas independent entry would be socially optimal, (ii) it leads to a sub-optimal contractual price when the exclusive dealing include a price commitment, (iii) it may deter entry altogether.Technology Transfer; Inefficient Entry; Antitrust; Authority's Behavior

Exclusive Dealing: The Interaction between Foreclosure and Investment Promotion

This paper studies a model where exclusive dealing (ED) can both promote investment and foreclose a more efficient supplier. While investment promotion is usually regarded as a pro-competitive effect of ED, our paper shows that it may be the very reason why a contract that forecloses a more efficient supplier is signed. Absent the effect on investment, the contract would not be signed and foreclosure would not be a concern. For this reason, considering potential foreclosure and investment promotion in isolation and then summing them up may not be a suitable approach to assess the net effect of ED. The paper therefore invites a more cautious attitude towards accepting possible investment promotion arguments as a defence for ED.Monopolization Practices, Vertical Agreements

Auditory and cognitive performance in elderly musicians and nonmusicians

Musicians represent a model for examining brain and behavioral plasticity in terms of cognitive and auditory profile, but few studies have investigated whether elderly musicians have better auditory and cognitive abilities than nonmusicians. The aim of the present study was to examine whether being a professional musician attenuates the normal age-related changes in hearing and cognition. Elderly musicians still active in their profession were compared with nonmusicians on auditory performance (absolute threshold, frequency intensity, duration and spectral shape discrimination, gap and sinusoidal amplitude-modulation detection), and on simple (short-term memory) and more complex and higher-order (working memory [WM] and visuospatial abilities) cognitive tasks. The sample consisted of adults at least 65 years of age. The results showed that older musicians had similar absolute thresholds but better supra-threshold discrimination abilities than nonmusicians in four of the six auditory tasks administered. They also had a better WM performance, and stronger visuospatial abilities than nonmusicians. No differences were found between the two groups\u2019 short-term memory. Frequency discrimination and gap detection for the auditory measures, and WM complex span tasks and one of the visuospatial tasks for the cognitive ones proved to be very good classifiers of the musicians. These findings suggest that life-long music training may be associated with enhanced auditory and cognitive performance, including complex cognitive skills, in advanced age. However, whether this music training represents a protective factor or not needs further investigation

On the analytic continuation of the critical line

We perform a numerical study of the systematic effects involved in the determination of the critical line at real baryon chemical potential by analytic continuation from results obtained at imaginary chemical potentials. We present results obtained in a theory free of the sign problem, three-color QCD with finite isospin chemical potential, and comment on general features which could be relevant also to the continuation of the critical line in real QCD at finite baryon density.Comment: 7 pages, 3 figures, Contribution to The XXVII International Symposium on Lattice Field Theory, Beijing, July 25-31, 200