Some continuation properties via minimax arguments

This note is devotes to some remarks regarding the use of variational methods, of minimax type, to establish continuity type result

High correlation between net promoter score and the development of consumers' willingness to pay (Empirical evidence from European mobile markets)

This paper shows that the correlation between the Net Promoter Score and consumers' Willingness To Pay in five European mobile markets is very strong. The Net Promoter Score is provided by a survey and the Willingness To Pay is calculated using the Spokes Model which is an economic model based on horizontal differentiation among firms. The model input data (firms' revenues, number of subscribers and profits) are provided by Merill Lynch, Bank of America. The well-known correlation between Net Promoter Score and Revenues is weaker and arises from the previous correlation. The same is true of the correlation between Net Promoter Score and Profits. --Net Promoter Score,recommend intention,customer satisfaction,consumer's Willingness to Pay

Competition through Technical Progress

The relationship between technical progress and price competition is a controversial issue in economics. This paper highlights the fact that investment in technical progress is an authentic type of competition which benefits the consumers rather than the industry. This type of competition exists when the potential for technical progress, which can be incorporated by firms through investment, is high enough. Competition is, in fact, made up of two components: A static one which is known as price or quantity competition and a dynamic one, the Technical Progress competition which also contribute to reduce prices and increase quantities for consumers. Consequently, the economic factors that increase a firm's margin do not have to be viewed as the consumers' enemy, but rather as an ally, under specific conditions, because they allow higher investments in new technology by which firms increase their capacities and attract higher demand from consumers. This paper also underlines that, for a mature market, the maximum Consumer Surplus as well as Social Welfare are attained by a constant level of combined competition which is only dependent on the size of the market and the number of firms. The level of combined competition can be defined as the product of the static and the dynamic level of competition. As a consequence, the higher the potential of technical progress is, the lower the level of static competition must be in order to reach the maximum level of Consumer Surplus and Social Welfare. --Investment,Competition,Technical Progress,Dynamic Competition

Sharp non-existence results of prescribed L^2-norm solutions for some class of Schr\"odinger-Poisson and quasilinear equations

In this paper we study the existence of minimizers for F(u) = \1/2\int_{\R^3} |\nabla u|^2 dx + 1/4\int_{\R^3}\int_{\R^3}\frac{| u(x) |^2| u(y) |^2}{| x-y |}dxdy-\frac{1}{p}\int_{\R^3}| u |^p dx on the constraint $$S(c) = \{u \in H^1(\R^3) : \int_{\R^3}|u|^2 dx = c \},$$ where $c>0$ is a given parameter. In the range $p \in [3, 10/3]$ we explicit a threshold value of $c>0$ separating existence and non-existence of minimizers. We also derive a non-existence result of critical points of $F(u)$ restricted to $S(c)$ when $c>0$ is sufficiently small. Finally, as a byproduct of our approaches, we extend some results of \cite{CJS} where a constrained minimization problem, associated to a quasilinear equation, is considered.Comment: 22 page

Role of access charges in the migration from copper to FTTH

We consider a horizontally and vertically differentiated duopoly model in order to analyze both intra- and inter-platform competition in an always corvered broadband access market (Copper-Copper, Copper-FTTH and FTTH-FTTH competitions). The model is purely static and does not address dynamic efficiency issues. It shows that the access charges play a significant role in the migration from copper to FTTH and in FTTH investment incentives, provided that consumers are segmented. In FTTH-infrastructure-based competition, investment incentives tend to increase with the copper access charge, while in FTTH-servicebased competition, FTTH investment incentives are much more sensitive to the FTTH access charge than to the copper access charge. A comparison of FTTH-infrastructure-based and FTTH-service-based competition in terms of nationwide FTTH coverage and social welfare indicates that FTTH-infrastructure-based competition leads to a higher level of nationwide FTTH coverage and social welfare. --

Multi-peak solutions for magnetic NLS equations without non--degeneracy conditions

In the work we consider the magnetic NLS equation (\frac{\hbar}{i} \nabla -A(x))^2 u + V(x)u - f(|u|^2)u = 0 \quad {in} \R^N where $N \geq 3$, $A \colon \R^N \to \R^N$ is a magnetic potential, possibly unbounded, $V \colon \R^N \to \R$ is a multi-well electric potential, which can vanish somewhere, $f$ is a subcritical nonlinear term. We prove the existence of a semiclassical multi-peak solution u\colon \R^N \to \C, under conditions on the nonlinearity which are nearly optimal.Comment: Important modification in the last part of the pape