Abstract
We merge the two-sided markets duopoly model of Armstrong (2006) with the nested vertical and horizontal differentiation model of Gabszewicz and Wauthy (2012), which consists of a linear city with different consumer densities on the left and on the right side of the city. In equilibrium, the high-quality platform sells at a higher price and captures a greater market share than the low-quality platform, despite the indifferent consumer being closer to the high-quality platform. The difference between market shares is lower than socially optimal. A perturbation that introduces a negligible difference between the consumer density on the left and on the right side of the city may disrupt existence of equilibrium in the model of Armstrong (2006).

Abstract
In this paper, we develop a theoretical model that enriches the literature on the pros and cons of ownership unbundling vis-A -vis lighter unbundling frameworks in the natural gas markets. For each regulatory framework, we compute equilibrium outcomes when an incumbent firm and a new entrant compete A la Cournot in the final gas market. We find that the entrant's contracting conditions in the upstream market and the transmission tariff are key determinants of the market structure in the downstream gas market (both with ownership and with legal unbundling). We also study how the regulator must optimally set transmission tariffs in each of the two unbundling regimes. We conclude that welfare maximizing tariffs often require free access to the transmission network (in both regulatoy regimes). However, when the regulator aims at promoting the break-even of the regulated transmission system operator, the first-best tariff is unfeasible in both regimes. Hence, we study a more realistic set-up, in which the regulator's action is constrained by the break-even of the regulated firm (the transmission system operator). In this set-up, we find that, for a given transmission tariff, final prices in the downstream market are always higher with ownership unbundling than with legal unbundling.

Abstract
This paper examines how firms should allocate their advertising budgets between consumers who have a high preference for their products (i.e., strong segment) and those who prefer competing products (i.e., weak segment). Targeted advertising transmits relevant information to otherwise uninformed consumers and it is used as a price discrimination device. With targeted advertising and price discrimination, we find that, when the attractiveness of the weak segment is low, each firm advertises more intensively in its strong segment. The same result arises when the attractiveness of the weak segment is high and advertising is sufficiently expensive. Interestingly, when the attractiveness of the weak segment is high but advertising costs are sufficiently low, it is optimal for each firm to advertise more intensively in its weak segment. The paper also investigates how advertising strategies and equilibrium profits are affected by price discrimination. Compared with uniform pricing, firms can increase or reduce the intensity of advertising targeted to each segment when price discrimination is allowed. Furthermore, when the attractiveness of the weak market is high, price discrimination boosts firms' profits provided that advertising costs are sufficiently low. The reverse happens when advertising costs are high.

Abstract
O artigo discute a importância da indústria de petróleo para a economia do estado do Rio de Janeiro e municípios produtores. Através de dados, mostra o papel que o boom das commodities teve sobre a dinâmica econômica fluminense. Por fim, apresenta questõe

Abstract
The new concept development is a critical stage of the innovation process that can be seen as a new knowledge creation process. This paper presents a new approach and a software tool for a collaborative new concept development. Our approach considers Collaborative Innovation Networks as ecosystems for new knowledge creation and integration, and Web Mashups as supporting platforms for the development of virtual co-learning and knowledge co-creation environments. The achieved results confirm the utility and efficacy of the software tool and allow foreseeing its suitability for use in educational contexts.

Abstract
This Fall Issue will discuss about the power of technology and Internet. Innovation is taking place everywhere through new and emerging technologies changing the way we think, live, breathe, travel, and do shopping to name a few areas. Funny enough is that some of us believe that the most important technologies are on the market available to please customers and users, and nothing more important will show up later. We, as humans, systematically underestimate the power of technology and its impact on daily life. There are several well-known quotations from very smart people which have turned ridiculous after some time by basically shifting initial assumptions into market knowledge. Whatever is too expensive and complex today becomes a commodity in no time and shortly after doesn’t bring competitive advantage any longer (the S-curve effect, see e.g Bayus, 1998 or Rogers, 1962, for different explanations). Several notable studies illustrate (like the well cited and used BCG tools) how rapidly diffusion is influencing production costs and consequently, accelerates the speed of diffusion itself. The question here stems from where the balance between the minority of ‘crazy’ developers and the majority of pioneering consumers willing to try something new lies.  (...)