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  1. Article ; Online: Synchronizing distant nodes: a universal classification of networks.

    Flunkert, V / Yanchuk, S / Dahms, T / Schöll, E

    Physical review letters

    2010  Volume 105, Issue 25, Page(s) 254101

    Abstract: Stability of synchronization in delay-coupled networks of identical units generally depends in a complicated way on the coupling topology. We show that for large coupling delays synchronizability relates in a simple way to the spectral properties of the ... ...

    Abstract Stability of synchronization in delay-coupled networks of identical units generally depends in a complicated way on the coupling topology. We show that for large coupling delays synchronizability relates in a simple way to the spectral properties of the network topology. The master stability function used to determine the stability of synchronous solutions has a universal structure in the limit of large delay: It is rotationally symmetric around the origin and increases monotonically with the radius in the complex plane. This allows a universal classification of networks with respect to their synchronization properties and solves the problem of complete synchronization in networks with strongly delayed coupling.
    Language English
    Publishing date 2010-12-17
    Publishing country United States
    Document type Journal Article
    ZDB-ID 208853-8
    ISSN 1079-7114 ; 0031-9007
    ISSN (online) 1079-7114
    ISSN 0031-9007
    DOI 10.1103/PhysRevLett.105.254101
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  2. Book ; Thesis: Die Hagen von Salzgitter-Gebhardshagen, Braunschweig, Gandersheim und des Klützer Ortes

    Dahms, Thomas

    eine regionale Vergleichsstudie zur mittelalterlichen Wald- und Siedlungsgeschichte in Niedersachsen und Mecklenburg

    (Salzgitter-Forschungen ; 4)

    2003  

    Title variant Studien zur Siedlungsgeschichte im Mittelalter am Beispiel niedersächsischer und mecklenburgischer Hagen-Orte
    Author's details Thomas Dahms
    Series title Salzgitter-Forschungen ; 4
    Keywords Hagen ; Mecklenburg ; Niedersachsen
    Language German
    Size 160 S, zahlr. Kt
    Publisher Archiv der Stadt
    Publishing place Salzgitter
    Document type Book ; Thesis
    Thesis / German Habilitation thesis Univ., Diss. u.d.T.: Dahms, Thomas: Studien zur Siedlungsgeschichte im Mittelalter am Beispiel niedersächsischer und mecklenburgischer Hagen-Orte--Göttingen, 1999
    Database Former special subject collection: coastal and deep sea fishing

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  3. Article ; Online: Cluster and group synchronization in delay-coupled networks.

    Dahms, Thomas / Lehnert, Judith / Schöll, Eckehard

    Physical review. E, Statistical, nonlinear, and soft matter physics

    2012  Volume 86, Issue 1 Pt 2, Page(s) 16202

    Abstract: We investigate the stability of synchronized states in delay-coupled networks where synchronization takes place in groups of different local dynamics or in cluster states in networks with identical local dynamics. Using a master stability approach, we ... ...

    Abstract We investigate the stability of synchronized states in delay-coupled networks where synchronization takes place in groups of different local dynamics or in cluster states in networks with identical local dynamics. Using a master stability approach, we find that the master stability function shows a discrete rotational symmetry depending on the number of groups. The coupling matrices that permit solutions on group or cluster synchronization manifolds show a very similar symmetry in their eigenvalue spectrum, which helps to simplify the evaluation of the master stability function. Our theory allows for the characterization of stability of different patterns of synchronized dynamics in networks with multiple delay times, multiple coupling functions, but also with multiple kinds of local dynamics in the networks' nodes. We illustrate our results by calculating stability in the example of delay-coupled semiconductor lasers and in a model for neuronal spiking dynamics.
    MeSH term(s) Action Potentials/physiology ; Animals ; Biological Clocks/physiology ; Computer Simulation ; Feedback, Physiological/physiology ; Humans ; Models, Neurological ; Nerve Net/physiology ; Neurons/physiology ; Oscillometry/methods
    Language English
    Publishing date 2012-07
    Publishing country United States
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ISSN 1550-2376
    ISSN (online) 1550-2376
    DOI 10.1103/PhysRevE.86.016202
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  4. Article ; Online: Genetic diversity and origin of the feral horses in Theodore Roosevelt National Park.

    Ovchinnikov, Igor V / Dahms, Taryn / Herauf, Billie / McCann, Blake / Juras, Rytis / Castaneda, Caitlin / Cothran, E Gus

    PloS one

    2018  Volume 13, Issue 8, Page(s) e0200795

    Abstract: Feral horses in Theodore Roosevelt National Park (TRNP) represent an iconic era of the North Dakota Badlands. Their uncertain history raises management questions regarding origins, genetic diversity, and long-term genetic viability. Hair samples with ... ...

    Abstract Feral horses in Theodore Roosevelt National Park (TRNP) represent an iconic era of the North Dakota Badlands. Their uncertain history raises management questions regarding origins, genetic diversity, and long-term genetic viability. Hair samples with follicles were collected from 196 horses in the Park and used to sequence the control region of mitochondrial DNA (mtDNA) and to profile 12 autosomal short tandem repeat (STR) markers. Three mtDNA haplotypes found in the TRNP horses belonged to haplogroups L and B. The control region variation was low with haplotype diversity of 0.5271, nucleotide diversity of 0.0077 and mean pairwise difference of 2.93. We sequenced one mitochondrial genome from each haplotype determined by the control region. Two complete mtDNA sequences of haplogroup L were closely related to the mtDNA of American Paint horse. The TRNP haplotype B did not have close matches in GenBank. The phylogenetic test placed this sequence in a group consisting of two horses from China, one from Yakutia, and one from Italy raising a possibility of historical transportation of horses from Siberia and East Asia to North America. Autosomal STR loci were polymorphic and indicated that the TRNP horses were distinctly different from 48 major horse breeds. Heterozygosity, mean number of alleles, and other measures of diversity indicated that TRNP herd diversity was below that observed for most other feral herds and domestic breeds. Both mtDNA and STRs demonstrated that the existing genetic data sets of horses are insufficient to determine the exact origins of the TRNP horses. However, measures of nuclear and mitochondrial diversity have elucidated management needs. It is recommended that new genetic stock be introduced and that adaptive management principles are employed to ensure that unique mitochondrial lineages are preserved and genetic diversity is increased and maintained over time.
    MeSH term(s) Animals ; Animals, Wild/genetics ; DNA, Mitochondrial ; Genetic Variation ; Genome, Mitochondrial ; Hair Follicle ; Haplotypes ; Horses/genetics ; North Dakota ; Parks, Recreational ; Phylogeny ; Selective Breeding/genetics ; Species Specificity
    Chemical Substances DNA, Mitochondrial
    Language English
    Publishing date 2018-08-01
    Publishing country United States
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ISSN 1932-6203
    ISSN (online) 1932-6203
    DOI 10.1371/journal.pone.0200795
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  5. Article: Stabilizing continuous-wave output in semiconductor lasers by time-delayed feedback.

    Dahms, Thomas / Hövel, Philipp / Schöll, Eckehard

    Physical review. E, Statistical, nonlinear, and soft matter physics

    2008  Volume 78, Issue 5 Pt 2, Page(s) 56213

    Abstract: The stabilization of steady states is studied in a modified Lang-Kobayashi model of a semiconductor laser. We show that multiple time-delayed feedback, realized by a Fabry-Perot resonator coupled to the laser, provides a valuable tool for the suppression ...

    Abstract The stabilization of steady states is studied in a modified Lang-Kobayashi model of a semiconductor laser. We show that multiple time-delayed feedback, realized by a Fabry-Perot resonator coupled to the laser, provides a valuable tool for the suppression of unwanted intensity pulsations, and leads to stable continuous-wave operation. The domains of control are calculated in dependence on the feedback strength, delay time (cavity round trip time), memory parameter (mirror reflectivity), latency time, feedback phase, and bandpass filtering. Due to the optical feedback, multistable behavior can also occur in the form of delay-induced intensity pulsations or other modes for certain choices of the control parameters. Control may then still be achieved by slowly ramping the injection current during turn-on.
    Language English
    Publishing date 2008-11
    Publishing country United States
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ISSN 1539-3755
    ISSN 1539-3755
    DOI 10.1103/PhysRevE.78.056213
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  6. Article ; Online: Discontinuous attractor dimension at the synchronization transition of time-delayed chaotic systems.

    Zeeb, Steffen / Dahms, Thomas / Flunkert, Valentin / Schöll, Eckehard / Kanter, Ido / Kinzel, Wolfgang

    Physical review. E, Statistical, nonlinear, and soft matter physics

    2013  Volume 87, Issue 4, Page(s) 42910

    Abstract: The attractor dimension at the transition to complete synchronization in a network of chaotic units with time-delayed couplings is investigated. In particular, we determine the Kaplan-Yorke dimension from the spectrum of Lyapunov exponents for iterated ... ...

    Abstract The attractor dimension at the transition to complete synchronization in a network of chaotic units with time-delayed couplings is investigated. In particular, we determine the Kaplan-Yorke dimension from the spectrum of Lyapunov exponents for iterated maps and for two coupled semiconductor lasers. We argue that the Kaplan-Yorke dimension must be discontinuous at the transition and compare it to the correlation dimension. For a system of Bernoulli maps, we indeed find a jump in the correlation dimension. The magnitude of the discontinuity in the Kaplan-Yorke dimension is calculated for networks of Bernoulli units as a function of the network size. Furthermore, the scaling of the Kaplan-Yorke dimension as well as of the Kolmogorov entropy with system size and time delay is investigated.
    Language English
    Publishing date 2013-04
    Publishing country United States
    Document type Journal Article
    ISSN 1550-2376
    ISSN (online) 1550-2376
    DOI 10.1103/PhysRevE.87.042910
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  7. Article ; Online: Adaptation controls synchrony and cluster states of coupled threshold-model neurons.

    Ladenbauer, Josef / Lehnert, Judith / Rankoohi, Hadi / Dahms, Thomas / Schöll, Eckehard / Obermayer, Klaus

    Physical review. E, Statistical, nonlinear, and soft matter physics

    2013  Volume 88, Issue 4, Page(s) 42713

    Abstract: We analyze zero-lag and cluster synchrony of delay-coupled nonsmooth dynamical systems by extending the master stability approach, and apply this to networks of adaptive threshold-model neurons. For a homogeneous population of excitatory and inhibitory ... ...

    Abstract We analyze zero-lag and cluster synchrony of delay-coupled nonsmooth dynamical systems by extending the master stability approach, and apply this to networks of adaptive threshold-model neurons. For a homogeneous population of excitatory and inhibitory neurons we find (i) that subthreshold adaptation stabilizes or destabilizes synchrony depending on whether the recurrent synaptic excitatory or inhibitory couplings dominate, and (ii) that synchrony is always unstable for networks with balanced recurrent synaptic inputs. If couplings are not too strong, synchronization properties are similar for very different coupling topologies, i.e., random connections or spatial networks with localized connectivity. We generalize our approach for two subpopulations of neurons with nonidentical local dynamics, including bursting, for which activity-based adaptation controls the stability of cluster states, independent of a specific coupling topology.
    MeSH term(s) Adaptation, Physiological ; Membrane Potentials ; Models, Neurological ; Nerve Net/cytology ; Nerve Net/physiology ; Neurons/cytology
    Language English
    Publishing date 2013-10
    Publishing country United States
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ISSN 1550-2376
    ISSN (online) 1550-2376
    DOI 10.1103/PhysRevE.88.042713
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  8. Article ; Online: Experimental observations of group synchrony in a system of chaotic optoelectronic oscillators.

    Williams, Caitlin R S / Murphy, Thomas E / Roy, Rajarshi / Sorrentino, Francesco / Dahms, Thomas / Schöll, Eckehard

    Physical review letters

    2013  Volume 110, Issue 6, Page(s) 64104

    Abstract: We experimentally demonstrate group synchrony in a network of four nonlinear optoelectronic oscillators with time-delayed coupling. We divide the nodes into two groups of two each, by giving each group different parameters and by enabling only intergroup ...

    Abstract We experimentally demonstrate group synchrony in a network of four nonlinear optoelectronic oscillators with time-delayed coupling. We divide the nodes into two groups of two each, by giving each group different parameters and by enabling only intergroup coupling. When coupled in this fashion, the two groups display different dynamics, with no isochronal synchrony between them, but the nodes in a single group are isochronally synchronized, even though there is no intragroup coupling. We compare experimental behavior with theoretical and numerical results.
    Language English
    Publishing date 2013-02-08
    Publishing country United States
    Document type Journal Article
    ZDB-ID 208853-8
    ISSN 1079-7114 ; 0031-9007
    ISSN (online) 1079-7114
    ISSN 0031-9007
    DOI 10.1103/PhysRevLett.110.064104
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  9. Article ; Online: Controlling synchrony by delay coupling in networks: from in-phase to splay and cluster states.

    Choe, Chol-Ung / Dahms, Thomas / Hövel, Philipp / Schöll, Eckehard

    Physical review. E, Statistical, nonlinear, and soft matter physics

    2010  Volume 81, Issue 2 Pt 2, Page(s) 25205

    Abstract: We study synchronization in delay-coupled oscillator networks using a master stability function approach. Within a generic model of Stuart-Landau oscillators (normal form of supercritical or subcritical Hopf bifurcation), we derive analytical stability ... ...

    Abstract We study synchronization in delay-coupled oscillator networks using a master stability function approach. Within a generic model of Stuart-Landau oscillators (normal form of supercritical or subcritical Hopf bifurcation), we derive analytical stability conditions and demonstrate that by tuning the coupling phase one can easily control the stability of synchronous periodic states. We propose the coupling phase as a crucial control parameter to switch between in-phase synchronization or desynchronization for general network topologies or between in-phase, cluster, or splay states in unidirectional rings. Our results are robust even for slightly nonidentical elements of the network.
    Language English
    Publishing date 2010-02
    Publishing country United States
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ISSN 1550-2376
    ISSN (online) 1550-2376
    DOI 10.1103/PhysRevE.81.025205
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  10. Article: Control of unstable steady states by extended time-delayed feedback.

    Dahms, Thomas / Hövel, Philipp / Schöll, Eckehard

    Physical review. E, Statistical, nonlinear, and soft matter physics

    2007  Volume 76, Issue 5 Pt 2, Page(s) 56201

    Abstract: Time-delayed feedback methods can be used to control unstable periodic orbits as well as unstable steady states. We present an application of extended time delay autosynchronization introduced by Socolar [Phys. Rev. E 50, 3245 (1994)] to an unstable ... ...

    Abstract Time-delayed feedback methods can be used to control unstable periodic orbits as well as unstable steady states. We present an application of extended time delay autosynchronization introduced by Socolar [Phys. Rev. E 50, 3245 (1994)] to an unstable focus. This system represents a generic model of an unstable steady state which can be found, for instance, in Hopf bifurcation. In addition to the original controller design, we investigate effects of control loop latency and a bandpass filter on the domain of control. Furthermore, we consider coupling of the control force to the system via a rotational coupling matrix parametrized by a variable phase. We present an analysis of the domain of control and support our results by numerical calculations.
    Language English
    Publishing date 2007-11
    Publishing country United States
    Document type Journal Article
    ISSN 1539-3755
    ISSN 1539-3755
    DOI 10.1103/PhysRevE.76.056201
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