Enhanced Ferromagnetic Stability in Cu Doped Passivated GaN Nanowires

Density functional calculations are performed to investigate the room temperature ferromagnetism in GaN:Cu nanowires (NWs). Our results indicate that two Cu dopants are most stable when they are near each other. Compared to bulk GaN:Cu, we find that magnetization and ferromagnetism in Cu doped NWs is strongly enhanced because the band width of the Cu td band is reduced due to the 1D nature of the NW. The surface passivation is shown to be crucial to sustain the ferromagnetism in GaN:Cu NWs. These findings are in good agreement with experimental observations and indicate that ferromagnetism in this type of systems can be tuned by controlling the size or shape of the host materials.Comment: Nano Lett., ASAP Article, 10.1021/nl080261

A gap analysis of Internet-of-Things platforms

We are experiencing an abundance of Internet-of-Things (IoT) middleware solutions that provide connectivity for sensors and actuators to the Internet. To gain a widespread adoption, these middleware solutions, referred to as platforms, have to meet the expectations of different players in the IoT ecosystem, including device providers, application developers, and end-users, among others. In this article, we evaluate a representative sample of these platforms, both proprietary and open-source, on the basis of their ability to meet the expectations of different IoT users. The evaluation is thus more focused on how ready and usable these platforms are for IoT ecosystem players, rather than on the peculiarities of the underlying technological layers. The evaluation is carried out as a gap analysis of the current IoT landscape with respect to (i) the support for heterogeneous sensing and actuating technologies, (ii) the data ownership and its implications for security and privacy, (iii) data processing and data sharing capabilities, (iv) the support offered to application developers, (v) the completeness of an IoT ecosystem, and (vi) the availability of dedicated IoT marketplaces. The gap analysis aims to highlight the deficiencies of today's solutions to improve their integration to tomorrow's ecosystems. In order to strengthen the finding of our analysis, we conducted a survey among the partners of the Finnish IoT program, counting over 350 experts, to evaluate the most critical issues for the development of future IoT platforms. Based on the results of our analysis and our survey, we conclude this article with a list of recommendations for extending these IoT platforms in order to fill in the gaps.Comment: 15 pages, 4 figures, 3 tables, Accepted for publication in Computer Communications, special issue on the Internet of Things: Research challenges and solution