Architecture of a large scale location service

Many mobile applications require some knowledge about the current geographic locations of the mobile objects involved. Therefore, services exist that can store and retrieve the position of mobile objects in an efficient and scalable way. More advanced location-aware applications, however, require additional functionality, like determining all mobile objects inside a certain geographic area (range query). This functionality is not supported by existing services on a large scale yet. In this paper, we present a generic large-scale location service. We describe the location service model, defining the semantics of position, range and nearest neighbor queries. A hierarchical distributed architecture is presented, which can efficiently process these queries, and the structure of a main-memory database for efficiently storing and retrieving position information on a location server. Finally, through measurements on a first prototype of this architecture, we show the feasibility of such a location service

A comparison of protocols for updating location information

The detailed location information of mobile objects, for example that of a user with a mobile computer or phone, is an important input for many location-aware applications. However, constantly updating the location information for thousands of mobile objects is not feasible. Update protocols for location information therefore use the special properties of this information to transmit it as efficiently as possible, that is requiring only few update messages, while still being effective in returning the location information with the desired accuracy. Different classes of such update protocols are described in this paper and a new combined protocol is proposed. To be able to compare their effectiveness and efficiency, we present an analysis for the minimum and average resulting accuracy of the location information on the receiver and the number of messages transmitted between them. We also present some simulation results, which we have performed to back up our analysis

Abschlußbericht der Projektgruppe Evolutionäre Algorithmen

Viele in der Praxis interessante Optimierungsrobleme sind NP-hart. Da kein Algorithmus bekannt ist, der ein Optimum für solche Probleme mit geringerem als exponentiellem Aufwand findet, sucht man, ein Optimum mit Heuristiken möglicht gut anzunähern. Zu diesen gehören auch die Evolutionären Algorithmen. Ziel der Projektgruppe EVA war die Entwicklung einer Experimentierplattform für Evolutionäre Algorithmen, die die Implementierung und empirische Untersuchung dieser Algorithmen erleichtert. Besonderer Wert wurde daher auf möglichst große Unabhängigkeit der Algorithmen vom Problem gelegt. Der Endbericht der Projektgruppe enthält nach einer Einführung den Entwurf von GENOM, die Beschreibung der Implementierung sowie Hinweise zur Bedienung und zu Erweiterungsmöglichkeiten

A map-based dead reckoning protocol for updating location information

An important aspect of location-aware services is the management of location information. To this end, location information needs to be transferred from a mobile device, which determines this information by means of a local positioning sensor (such as GPS), to a location service, where the location information can be queried by applications. Because bandwidth in wide area mobile communications is still scarce and expensive, it is important to use an update protocol that requires as few messages as possible while still guaranteeing a desired accuracy of the location information. To decrease the number of necessary update messages, so-called dead-reckoning strategies have been proposed. In this paper we give an overview of different variants of dead-reckoning protocols for updating location information and propose a new map-based protocol. While a simple dead-reckoning protocol already reduces the number of update messages by up to 83, the map-based protocol further reduces their number by again up to 60

CT Texture Analysis of Pulmonary Neuroendocrine Tumors—Associations with Tumor Grading and Proliferation

Texture analysis derived from computed tomography (CT) might be able to provide clinically relevant imaging biomarkers and might be associated with histopathological features in tumors. The present study sought to elucidate the possible associations between texture features derived from CT images with proliferation index Ki-67 and grading in pulmonary neuroendocrine tumors. Overall, 38 patients (n = 22 females, 58%) with a mean age of 60.8 ± 15.2 years were included into this retrospective study. The texture analysis was performed using the free available Mazda software. All tumors were histopathologically confirmed. In discrimination analysis, “S(1,1)SumEntrp” was significantly different between typical and atypical carcinoids (mean 1.74 ± 0.11 versus 1.79 ± 0.14, p = 0.007). The correlation analysis revealed a moderate positive association between Ki-67 index with the first order parameter kurtosis (r = 0.66, p = 0.001). Several other texture features were associated with the Ki-67 index, the highest correlation coefficient showed “S(4,4)InvDfMom” (r = 0.59, p = 0.004). Several texture features derived from CT were associated with the proliferation index Ki-67 and might therefore be a valuable novel biomarker in pulmonary neuroendocrine tumors. “Sumentrp” might be a promising parameter to aid in the discrimination between typical and atypical carcinoids

Magnetic Resonance Imaging of Peritoneal Carcinomatosis: Evaluation of High b-Value Computed Diffusion-Weighted Imaging

Over the last few years, diffusion-weighted imaging (DWI) has become increasingly relevant in the diagnostic assessment of peritoneal carcinomatosis. The aim of this study was to investigate the benefits of high-b DWI (c-DWI) compared to standard DWI in patients with peritoneal carcinomatosis. A cohort of 40 patients with peritoneal carcinomatosis were included in this retrospective study. DWI was performed with b-values of 50, 400, and 800 or 1000 s/mm2 on a 1.5-T magnetic resonance imaging (MRI) scanner. C-DWI was calculated using a mono-exponential model with high b-values of 1000, 2000, 3000, 4000, and 5000 s/mm2. All c-DWI images with high b-values were compared in terms of volume, detectability of peritoneal lesions, and image quality with the DWI sequence acquired with a b-value of 800 or 1000 s/mm2 by two readers. In the group with a b-value of 800 s/mm2, there was no statistically significant difference in terms of lesion volume. In the second group with a b-value of 1000 s/mm2, peritoneal carcinomatosis lesions were statistically significantly larger than in the c-DWI with a- high b-value of 2000 s/mm2 (median 7 cm3, range 1–26 cm3vs. median 6 cm3, range 1–83 cm3, p < 0.05). In both groups, there was a marked decrease in the detectability of peritoneal lesions starting at b = 2000 s/mm2. In addition, image quality decreased noticeably from c-DWI at b = 3000 s/mm2. In both groups, all images with high b-values at b = 4000 s/mm2 and 5000 s/mm2 were not diagnostically valuable due to poor image quality. The c-DWI technique offers good diagnostic performance without additional scanning time. High c-DWI b-values up to b = 1000 s/mm2 provide comparable detectability of peritoneal carcinomatosis compared to standard DWI. Higher b-values over 1500 s/mm2 result in lower image quality, which might lead to misdiagnosis

Das Nürnberger Kinderpanel: Zielsetzungen, theoretisches Ausgangsmodell, methodische Vorgehensweise sowie wissenschaftliche und praktische Relevanz

Zielsetzung der Studie ist die Gewinnung eines Paneldatensatzes zur Analyse (1) der Gesundheit, des Wohlbefindens, des gesundheitsbewußten Handelns und Wissens von Kindern, (2) der diese beeinflussenden Faktoren und (3) der Auswirkungen von Gesundheit und Wohlbefinden auf die Lebenssituation und Entwicklung von Kindern. Die Autoren nutzen dazu ein integriertes Modell, das sozialisationstheoretische, entwicklungspsychologische und kindheitsorientierte Perspektiven verknüpft und "Kinder als Werdende und Seiende" auffaßt. Kinder werden in diesem Modell als produktiv Realität verarbeitende Subjekte konzipiert im Sinne der akteursbezogenen Kindheitsforschung. Insgesamt will der Nürnberger Kinderpanel einen Beitrag zur Gesundheitsförderung und -planung leisten, da in der Studie Aussagen über die Entstehung von gesundheitsorientierten Lebensstilen und die sie ermöglichenden und behindernden Faktoren gemacht werden. (ICA

Nexus - an open global infrastructure for spatial-aware applications

Due to the lack of a generic platform for location- and spatial-aware systems, many basic services have to be reimplemented in each application that uses spatial-awareness. A cooperation among different applications is also difficult to achieve without a common platform. In this paper we present a platform that solves these problems. It provides an infrastructure that is based on computer models of regions of the physical world, which are augmented by virtual objects. We show how virtual objects make the integration of existing information systems and services in spatial-aware systems easier. Furthermore, our platform supports interactions between the computer models and the real world and integrates single models in a global 'Augmented World'

Nonlinear Supersymmetric Quantum Mechanics: concepts and realizations

Nonlinear SUSY approach to preparation of quantum systems with pre-planned spectral properties is reviewed. Possible multidimensional extensions of Nonlinear SUSY are described. The full classification of ladder-reducible and irreducible chains of SUSY algebras in one-dimensional QM is given. Emergence of hidden symmetries and spectrum generating algebras is elucidated in the context of Nonlinear SUSY in one- and two-dimensional QM.Comment: 75 pages, Minor corrections, Version published in Journal of Physics