Abstract
Joint implant-related infections, namely by Staphylococci, are a worldwide problem, whose consequences are dramatic Various methods are studied to fight against these infections. Here, the proposed solution consists in grafting a bioactive polymer on joint implant surfaces in order to allow the control of the interactions with the living system. In this study, sodium styrene sulfonate, bearing sulfonate groups, was grafted on the surface of titanium alloys. Scanning Electron Microscopy, colorimetric method, Fourier-transformed infrared spectroscopy and contact angle measurements were applied to characterize the surfaces. Bacterial adhesion studies were studied on poly(sodium styrene sulfonate) grafted Ti6Al4V and Ti6Al4V surfaces previously adsorbed by proteins involved in the bacteria adhesion process. Fibrinogen and fibronectin were demonstrated to increase staphylococcal adhesion on Ti6Al6V surfaces. Ti6Al4V grafted sodium styrene sulfonate surfaces inhibited the adhesion of Staphylococcus epidermidis in 37% and 13% on pre-adsorbed surfaces with fibrinogen anal fibronectin, respectively. The mechanism of the observed inhibiting bacteria adhesion properties is related to the differences of proteic conformations induced by poly(sodium styrene sulfonate) grafting.

Abstract
We explore the issue of minorities' survival in the presence of positive network externalities. We rely on a simple example of thematic clubs to illustrate why and how such survival problems might appear, first considering the case of simple-network effects (fully anonymous externalities) and then the case of cross-network effects (type-dependent externalities). In both cases, the analysis is framed as a simple noncooperative game with a continuum of players and binary action sets. There is a unique and interior Nash equilibrium under mild network effects and two corner equilibria under strong network effects, with one club driven out. A utilitarian planner would accentuate the clustering effects of network externalities, and call for the disappearance of the minority club more often than the noncooperative solution. A simple myopic learning algorithm capturing the progression of network lock-in effects is studied.

Abstract
This paper studies the dynamic price competition between two firms that sell horizontally differentiated durable goods and, subsequently, provide exclusive complementary goods and services to their customers. The paper analyzes how optimal pricing strategies are affected by the existence of network effects associated with the size of firms' consumer base. The interaction is thoroughly analyzed as a continuous time linear-quadratic differential game. We provide a necessary and sufficient condition for the existence of a unique duopoly equilibrium in affine strategies. When this condition holds, we show that optimal pricing strategies crucially depend on the nature of the network effects.

Abstract

Abstract
There is no consensus on the method to set transmission tariffs for natural gas. The entry-exit system is widely used in European markets because it is cost reflective, it allows the network users to separately book capacity for entry and exit points, beyond its pro-competitiveness characteristics. Some authors, however, defend the adoption of the postage stamp (where a single tariff is charged regardless of the origin of the gas), due to its simplicity. Our goal is to compare these two mechanisms of transmission tariff with respect to the impacts on welfare. We find that the welfare effects crucially depend on the size of the internal market and the fixed costs supported by the incumbent firm. If the domestic market is sufficiently large and there are imports from abroad, consumer surplus is higher under the postage stamp system.

Abstract
Service experience is the core of service offering. However, research on the role of the service environment when creating experiences is still underdeveloped, and even less empirical evidence is available that relates servicescape with customers' perceptions of value. Our purpose is to focus on the role of servicescape as a driver of customer experience by analyzing its impact on customer value creation and behavior. We have chosen an experience-centric service organization, a football club, to develop our analysis. A regression analysis was performed to determine the main drivers of value among ‘sportscape’ components and how it influenced customers' attitude and behavior. A total of 349 questionnaires were collected during a match of the Portuguese Football League at Dragon Stadium. Our analysis showed that servicescape influences consumer perceived value, attitudes, and behavior when creating service experiences: value-in-context generates customers' satisfaction, which in turn has a positive effect on their desire to repeat the experience. © 2014, Taylor & Francis.