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We developed a method, named GraFix, that considerably improves sample quality for structure determination by single-particle electron cryomicroscopy (cryo-EM). GraFix uses a glycerol gradient centrifugation step in which the complexes are centrifuged into an increasing concentration of a chemical fixation reagent to prevent aggregation and to stabilize(More)
In this paper, we propose a global tracking service for mobile agents, which is scalable to the Internet and accounts for security issues as well as the particularities of mobile agents (frequent changes in locations). The protocols we propose address agent impersonation, malicious location updates, as well as security issues that arise from profiling(More)
Current search engines crawl the Web, download content, and digest this content locally. For multimedia content, this involves considerable volumes of data. Furthermore, this process covers only publicly available content because content providers are concerned that they otherwise loose control over the distribution of their intellectual property. We(More)
In this paper we introduce the concept of context-aware services as an extended form of location-based services. We describe a new architecture for realizing context-aware services which has a number of key benefits. This architecture relays on mobile software agents as security-centric middleware. Our approach allows to combine disjunct databases by(More)
Current search engines crawl the Web, download content, and digest this content locally. For multimedia content, this involves considerable volumes of data. Furthermore, this process covers only publicly available content because content providers are concerned that they otherwise loose control over the distribution of their intellectual property. We(More)
Cytokines possess discrepant effects on tumour cells varying from anti-to proapoptotic activities. We recently reported that testicular germ cell tumours (TGCT) express a functional form of the proinflammatory cytokine interferon-gamma (IFNg). The present study asked whether TGCT-derived IFNg influences survival or death of neoplastic germ cells. Analysis(More)
Due to the many current weaknesses of security mechanisms in mobile technology, location based services essentially depend on security aware middleware and reliable multilateral security concepts. Neither the latest operating systems of mobile devices nor current concepts in wireless communication GPRS, WLAN, or Bluetooth meet the security requirements(More)
Assessed relationship between children's minor illnesses during the first 3 years of life and parenting stress in the 4th year. Also examined whether a good parenting alliance would compensate for or moderate this relationship. Parents of 56 3- to 4-year-olds completed parenting alliance and stress questionnaires. Child morbidity, assessed from medical(More)