Grunewald, Germany
Grunewald, Germany

Time filter

Source Type

Asselmeyer-Maluga T.,German Aerospace Center | Rose H.,Fraunhofer FIRST
General Relativity and Gravitation | Year: 2012

In this paper we discuss the question how matter may emerge from space. For that purpose we consider the smoothness structure of spacetime as underlying structure for a geometrical model of matter. For a large class of compact 4-manifolds, the elliptic surfaces, one is able to apply the knot surgery of Fintushel and Stern to change the smoothness structure. The influence of this surgery to the Einstein-Hilbert action is discussed. Using the Weierstrass representation, we are able to show that the knotted torus used in knot surgery is represented by a spinor fulfilling the Dirac equation and leading to a Dirac term in the Einstein-Hilbert action. For sufficient complicated links and knots, there are "connecting tubes" (graph manifolds, torus bundles) which introduce an action term of a gauge field. Both terms are genuinely geometrical and characterized by the mean curvature of the components. We also discuss the gauge group of the theory to be U(1) × SU(2) × SU(3). © 2012 Springer Science+Business Media, LLC.


Nikulin V.V.,Franklin University | Nikulin V.V.,Bernstein Center for Computational Neuroscience | Linkenkaer-Hansen K.,Center for Neurogenomics and Cognitive Research | Nolte G.,Fraunhofer FIRST | And 2 more authors.
Clinical Neurophysiology | Year: 2010

Objective: The aim of the present study was to show analytically and with simulations that it is the non-zero mean of neuronal oscillations, and not an amplitude asymmetry of peaks and troughs, that is a prerequisite for the generation of evoked responses through a mechanism of amplitude modulation of oscillations. Secondly, we detail the rationale and implementation of the "baseline-shift index" (BSI) for deducing whether empirical oscillations have non-zero mean. Finally, we illustrate with empirical data why the "amplitude fluctuation asymmetry" (AFA) index should be used with caution in research aimed at explaining variability in evoked responses through a mechanism of amplitude modulation of ongoing oscillations. Methods: An analytical approach, simulations and empirical MEG data were used to compare the specificity of BSI and AFA index to differentiate between a non-zero mean and a non-sinusoidal shape of neuronal oscillations. Results: Both the BSI and the AFA index were sensitive to the presence of non-zero mean in neuronal oscillations. The AFA index, however, was also sensitive to the shape of oscillations even when they had a zero mean. Conclusions: Our findings indicate that it is the non-zero mean of neuronal oscillations, and not an amplitude asymmetry of peaks and troughs, that is a prerequisite for the generation of evoked responses through a mechanism of amplitude modulation of oscillations. Significance: A clear distinction should be made between the shape and non-zero mean properties of neuronal oscillations. This is because only the latter contributes to evoked responses, whereas the former does not. © 2009 International Federation of Clinical Neurophysiology.


Wolf A.,Fraunhofer FIRST
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) | Year: 2011

In this article a constraint-based modeling of clinical pathways, in particular of surgical pathways, is introduced and used for an optimized scheduling of their tasks. The addressed optimization criteria are based on practical experiences in the area of Constraint Programming applications in medical work flow management. Objective functions having empirical evidence for their adequacy in the considered use cases are formally presented. It is shown how they are respected while scheduling clinical pathways. © 2011 Springer-Verlag.


Nikulin V.V.,Franklin University | Nikulin V.V.,Bernstein Center for Computational Neuroscience | Nolte G.,Fraunhofer FIRST | Curio G.,Franklin University | Curio G.,Bernstein Center for Computational Neuroscience
Clinical Neurophysiology | Year: 2012

Objective: We present a novel method for the extraction of neuronal components showing cross-frequency phase synchronization. Methods: In general the method can be applied for the detection of phase interactions between components with frequencies f1 and f2, where f2≈ rf1 and r is some integer. We refer to the method as cross-frequency decomposition (CFD), which consists of the following steps: (a) extraction of f1-oscillations with the spatio-spectral decomposition algorithm (SSD); (b) frequency modification of the f1-oscillations obtained with SSD; and (c) finding f2-oscillations synchronous with f1-oscillations using least-squares estimation. Results: Our simulations showed that CFD was capable of recovering interacting components even when the signal-to-noise ratio was as low as 0.01. An application of CFD to the real EEG data demonstrated that cross-frequency phase synchronization between alpha and beta oscillations can originate from the same or remote neuronal populations. Conclusions: CFD allows a compact representation of the sets of interacting components. The application of CFD to EEG data allows differentiating cross-frequency synchronization arising due to genuine neurophysiological interactions from interactions occurring due to quasi-sinusoidal waveform of neuronal oscillations. Significance: CFD is a method capable of extracting cross-frequency coupled neuronal oscillations even in the presence of strong noise. © 2011 International Federation of Clinical Neurophysiology.


Serbedzija N.,Fraunhofer FIRST
Proceedings - International Conference on Software Engineering | Year: 2010

Reflective assistance is concerned with the construction of flexible 'smart' systems that control the eldercare environment, adapting the functioning to the needs of the individual in real-time. In order to achieve this goal, systems must be capable of monitoring the behaviour of the elderly people and responding to dynamic changes in their performance, physical and psychological situation. This paper describes how reflective approach can be used to design and develop a home environment that offers medicare, rehabilitation exercises and improved comfort of elderly inhabitants. Copyright 2010 ACM.


Schutt A.,University of Melbourne | Wolf A.,Fraunhofer FIRST
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) | Year: 2010

The recent success of the lazy clause generator (a hybrid of a FD and a SAT solver) on resource-constrained project scheduling problems (RCPSP) shows the importance of the global cumulative constraint to tackle these problems. A key for an efficient cumulative propagator is a fast and correct pruning of time-bounds. The not-first/not-last rule (which is not subsumed by other rules) detects activities that cannot be run at first/last regarding to an activity set and prunes their time bounds. This paper presents a new sound not-first/not-last pruning algorithm which runs in O(n2 log n), where n is the number of activities. It may not find the best adjustments in the first run, but after at most n iterations. This approach of iteration fits the setup of constraint propagation quite naturally offering the opportunity that a fixed point is reached more efficiently. Moreover, it uses a novel approach of generation of some "artificial" activities in the context of triggering pruning rules correctly. In experiments on RCPSP amongst others from the well-established PSPLib we show that the algorithm runs negligible more often than a complete algorithm while taking its advantage from the lower - to the best of our knowledge the lowest known - runtime complexity. © 2010 Springer-Verlag.


Serbedzija N.,Fraunhofer FIRST
Lecture Notes of the Institute for Computer Sciences, Social-Informatics and Telecommunications Engineering | Year: 2012

Home nursing gains in significance with the human age being prolonged. More and more people reach the state when they need some assistance in order to live independently at their own. However, home nursing is a resource demanding activity stretching medicare to its limits. In this situation, new technology can help. Reflective assistance is concerned with the construction of flexible 'smart' systems that control the eldercare environment, adapting the ambient to the needs of individuals. New technology transforms a living space to a helpful residence assistant that observes inhabitants and offers aid or calls for it in the case of need. To achieve this goal, systems must be capable of monitoring the behavior of the elderly people and of responding to dynamic changes in their performance or physical and psychological situation. This paper describes an approach to design and develop a home ambient that offers medicare, mobile monitoring, rehabilitation exercises and improved comfort of elderly inhabitants. © 2012 ICST Institute for Computer Science, Social Informatics and Telecommunications Engineering.


Serbedzija N.,Fraunhofer FIRST
Lecture Notes of the Institute for Computer Sciences, Social-Informatics and Telecommunications Engineering, LNICST | Year: 2012

User-centric systems call for novel methods and tools for a tight and implicit man machine interaction. Often highly personalized system are sensitive and reactive to user psychological, social and physical situation. However providing such a support may cross the barriers of our privacy or may have impacts on us that we do not necessarily agree upon. © 2012 Springer-Verlag Berlin Heidelberg.


Serbedzija N.,Fraunhofer FIRST
Proceedings of the IASTED International Conference on Assistive Technologies, AT 2012 | Year: 2012

Future assistive technology needs adaptive, autonomous, intelligent and self-aware behavior to be able to offer solutions that are intuitively integrated in our everyday surroundings. New systems have to be as natural as possible. To achieve such an ideal it is necessary not only to develop new techniques but also to have a thorough understanding of the natural phenomena being modeled. This calls for highly multidisciplinary design teams gathering a wide spectrum of expertise. The paper describes how deployment of "natural" processes may improve functioning of technical systems, by illustrating effective deployment of adaptation in man-machine interface applied in automotive and homecare domains featuring autonomous and awareness-rich assistive behavior.


Serbedzija N.,Fraunhofer FIRST | Fairclough S.,Liverpool John Moores University
ACM Transactions on Autonomous and Adaptive Systems | Year: 2012

Pervasive adaptive systems are concerned with the construction of "smart" technologies capable of adapting to the needs of the individual in real time. In order to achieve this level of specificity, systems must be capable of monitoring the psychological status of the user and responding to these changes in real time and across multiple systems if necessary. This article describes a number of conceptual issues associated with this category of adaptive technology. The biocybernetic loop describes different approaches to monitoring the status of the user from physiological sensors to overt behavior. These data are used to drive real time system adaptation tailored to a specific user in a particular context. The rate at which the technology adapts to the individual user are described over three different phases of usage: awareness (short-term), adjustment (medium-term), and coevolution (long-term). An ontology is then proposed for the development of an adaptive software architecture that embodies this approach and may be extended to encompass several distinct loops working in parallel. The feasibility of the approach is assessed through implemented case studies of their performance and functionality. © 2012 ACM.

Loading Fraunhofer FIRST collaborators
Loading Fraunhofer FIRST collaborators