Remodeling of photosynthetic machinery induced by growing spinach plants under low light intensities reveals an up-regulation of light-harvesting complexes and down-regulation of photosystem II and cytochrome b6f complexes in intact thylakoids and isolated grana membranes. The antenna size of PSII increased by 40-60% as estimated by fluorescence induction and LHCII/PSII stoichiometry. These low-light-induced changes in the protein composition were accompanied by the formation of ordered particle arrays in the exoplasmic fracture face in grana thylakoids detected by freeze-fracture electron microscopy. Most likely these highly ordered arrays consist of PSII complexes. A statistical analysis of the particles in these structures shows that the distance of neighboring complexes in the same row is 18.0 nm, the separation between two rows is 23.7 nm, and the angle between the particle axis and the row is 26 degrees . On the basis of structural information on the photosystem II supercomplex, a model on the supramolecular arrangement was generated predicting that two neighboring complexes share a trimeric light-harvesting complex. It was suggested that the supramolecular reorganization in ordered arrays in low-light grana thylakoids is a strategy to overcome potential diffusion problems in this crowded membrane. Furthermore, the occurrence of a hexagonal phase of the lipid monogalactosyldiacylglycerol in grana membranes of low-light-adapted plants could trigger the rearrangement by changing the lateral membrane pressure.

Following the vision of an Internet of Things (IoT) real world objects are integrated into the Internet to provide data as sensors and to manipulate the real world as actors. While current IoT approaches focus on the integration of things based on service technologies, scenarios in domains like smart cities, automotive or crisis management require service platforms involving real world objects, backend-systems and mobile devices. In this paper we introduce a service platform based on the Extensible Messaging and Presence Protocol (XMPP) for the development and provision of services for such pervasive infrastructures. We argue for XMPP as protocol for unified, real-time communication and introduce the major concepts of our platform. Based on two case studies we demonstrate real-time capabilities of XMPP for remote robot control and service development in the e-mobility domain.

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Within the traditional telephone system a certain level of quality and security has been established over the years. If we try to use IP Telephony systems as a core part of our future communication infrastructure (e.g. as classical PBX enhancement or replacement) continuous high availability, stable and error-free operation and the protection of the privacy of the spoken word are challenges, that definitely have to be met. Since manufacturers start deploying new end systems and infrastructure components rather fast now -a critical inspection of their security features and vulnerabilities is mandatory. The critical presentation of the theoretical background of certain vulnerabilities, testing and attacking tools and the evaluation results reveals, that well-known security flaws become part of implementations in the new application area again and the security level of a number of examined solutions is rather insufficient.