Abstract

Abstract
Neo-Schumpeterian streams of research emphasize the close relationship between changes in economic structure in favor of high-skill and high-tech branches and rapid economic growth. They identify the emergence of a new technological paradigm in the 1970s, strongly based on the application of information and communication technologies (ICTs), arguing that in such periods of transition and emergence of new techno-economic paradigms, the intermediate development countries and the countries which are not at the technological frontier have higher opportunities to catch-up. Although this debate is theoretically well documented, the empirics seem to lag behind the theory. In this article, we contribute to this literature by adding enlightening evidence on the issue. More precisely, we relate the growth experiences of countries which had relatively similar economic structures in the late 1970s, with changes occurring in these countries' structures between 1979 and 2003. The results reveal a robust relationship between structure and (labor) productivity growth, and lend support to the view that producing (though not user) ICT-related industries are strategic branches of economic activity.

Abstract
The massive interconnection of offshore Wind Farms (WF) brings challenges for the operation of electric grids. The predicted amount of offshore wind power will lead to a smaller ratio of conventional units operating in the system. Thus, the power system will have less capability to provide fast dynamic regulation. Despite of offshore WF being able to inject power on the AC grid through High Voltage Direct Current (HVDC) convertors, they cannot participate on frequency support by the intrinsic decoupling that DC adoption brings. This paper proposes a control methodology, based on local controllers, to enable the participation of offshore WF in primary frequency control. Additionally, enhancements were made on the Wind Energy Converters (WEC) controller to make them capable of emulating inertial behaviour. Tests were performed in a multi-terminal DC network with two off shore wind farms to assess the feasibility and effectiveness of the concept in a communication-free framework.

Abstract
Ever since the first studies about biomedical implantable devices, the problem of how to energize them has stood out as both important and notoriously difficult to solve. In order to extend the lifetime of implants, it is imperative to develop power generators that are autonomous, safe and maintenance-free. Energy harvesting is a natural way of meeting these requirements. First, the energy source is theoretically everlasting, a fact that helps to guarantee the autonomy. Second, the energy is obtained from the environment of the application itself, contributing to its safety. Finally, a properly designed energy harvesting system is very unlikely to ever require maintenance. This paper follows this line and describes an electromagnetic power transducer that harvests electrical energy from the human gait and stores it. An efficient power management module uses the stored energy to energize the telemetric system of a smart hip prosthesis implant, enabling the early detection of loosening, the target application of this work. The system is able to extract a total 1912.5 mu J of usable energy under normal walking conditions.

Abstract
Ourmain interest is to study the relevant biological thresholds that appear in epidemic and immunological dynamical models. We compute the thresholds of the SIRI epidemic models that determine the appearance of an epidemic disease. We compute the thresholds of a Tregs immunological model that determine the appearance of an immune response.

Abstract
Despite the vitality and dynamism that the field of entrepreneurship has experienced in the last decade, the issue of whether it comprises an effective network of (in)formal communication linkages among the most influential scholars within the area has yet to be examined in depth. This study follows a formal selection procedure to delimit the 'relational environment' of the field of entrepreneurship and to analyze the existence and characterization of (in)visible college(s) based on a theoretically well-grounded framework, thus offering a comprehensive and up-to-date empirical analysis of entrepreneurship research. Based on more than a 1,000 papers published between 2005 and 2010 in seven core entrepreneurship journals and the corresponding (85,000) citations, we found that entrepreneurship is an (increasingly) autonomous, legitimate and cohesive (in)visible college, fine tuned through the increasing visibility of certain subject specialties (e.g., family business, innovation, technology and policy). Moreover, the rather dense formal links that characterize the entrepreneurship (in)visible college are accompanied by a reasonably solid network of informal relations maintained and sustained by the mobility of 'stars' and highly influential scholars. The limited internationalization of the entrepreneurship community, reflected in the almost total absence of non-English-speaking authors/studies/outlets, stands as a major quest for the field.