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Kato H, Soriano MC, Pereda E, Fischer I, Mirasso CR. Limits to detection of generalized synchronization in delay-coupled chaotic oscillators. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2013; 88:062924. [PMID: 24483548 DOI: 10.1103/physreve.88.062924] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/05/2013] [Indexed: 06/03/2023]
Abstract
We study how reliably generalized synchronization can be detected and characterized from time-series analysis. To that end, we analyze synchronization in a generalized sense of delay-coupled chaotic oscillators in unidirectional ring configurations. The generalized synchronization condition can be verified via the auxiliary system approach; however, in practice, this might not always be possible. Therefore, in this study, widely used indicators to directly quantify generalized and phase synchronization from noise-free time series of two oscillators are employed complementarily to the auxiliary system approach. In our analysis, none of the indices provide the consistent results of the auxiliary system approach. Our findings indicate that it is a major challenge to directly detect synchronization in a generalized sense between two oscillators that are connected via a chain of other oscillators, even if the oscillators are identical. This has major consequences for the interpretation of the dynamics of coupled systems and applications thereof.
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152
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Knochenmuss R, Fischer I, Lührs D, Lin Q. Intermolecular Excited-State Proton Transfer in Clusters of 1-Naphthol with Water and with Ammonia. Isr J Chem 2013. [DOI: 10.1002/ijch.199900029] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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153
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Herterich J, Gerbich T, Fischer I. Excited-State Dynamics of the 2-Methylallyl Radical. Chemphyschem 2013; 14:3906-8. [DOI: 10.1002/cphc.201300700] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2013] [Indexed: 11/08/2022]
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154
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Heinrich UR, Brieger J, Striedter C, Fischer I, Schmidtmann I, Li H, Mann WJ, Helling K. 17β-Estradiol reduces nitric oxide production in the Guinea pig cochlea. Horm Metab Res 2013; 45:887-92. [PMID: 23794402 DOI: 10.1055/s-0033-1347200] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Intense noise exposure and the application of ototoxic substances result in increased levels of reactive oxygen species (ROS) and reactive nitrogen species (RNS), such as nitric oxide (NO). In order to reduce the free NO concentration in the inner ear under pathological conditions, the use of natural cytoprotective substances such as 17β-estradiol is a promising therapeutic concept. In male guinea pigs the organ of Corti and the lateral wall were isolated from the cochlea and afterwards incubated for 6 h in cell-culture medium. 17β-Estradiol was adjusted in 2 concentrations to organ cultures of the right ears (12 animals per concentration). The left ears were used as controls. The NO production was quantified in the supernatant by chemiluminescence after incubation. Depending on the concentration, 17β-estradiol reduced NO in the organ of Corti by 43% (p=0.015) and 46% (p=0.026), respectively. In the lateral wall, the NO concentration was reduced by 24%, but without statistical significance (p=0.86). However, when analyzing the association between the 2 cochlear regions for each animal separately, the NO concentrations were lower in nearly all 17β-estradiol-treated ears compared to controls. In order to demonstrate the flexibility of the organ culture system, the NO donor DETA NONOate and the nitric oxide synthase inhibitors L-NAME and L-NMMA were applied. The electron microscopic analysis revealed a well-preserved cochlear cell morphology after incubation. The ability of 17β-estradiol to influence the NO production preferentially in the organ of Corti might offer new therapeutic perspectives for inner ear protection.
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155
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Hicke K, Porte X, Fischer I. Characterizing the deterministic nature of individual power dropouts in semiconductor lasers subject to delayed feedback. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2013; 88:052904. [PMID: 24329328 DOI: 10.1103/physreve.88.052904] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2013] [Revised: 10/07/2013] [Indexed: 06/03/2023]
Abstract
We implement a method to identify the deterministic nature of specific events in the dynamics of a semiconductor laser subject to time-delayed optical feedback. Specifically, we study the power dropouts in the low-frequency fluctuations regime on an individual event basis and identify whether the underlying dominant mechanism is deterministic. Our approach is based on sychronization with a twin system in a symmetric relay configuration. We investigate the dependence of the fraction of deterministically driven (i.e., synchronized) dropouts on the laser's pump current as a key parameter. Our experimental results are corroborated by numerical modeling based on rate equations. Our numerical findings also provide insights into the influence of spontaneous emission noise.
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156
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Fischer I, Franzreb M. Removal of the nonionic surfactant Eumulgin ES from protein solutions by means of adsorption and ultrafiltration. Sep Purif Technol 2013. [DOI: 10.1016/j.seppur.2013.07.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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157
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Flunkert V, Fischer I, Schöll E. Dynamics, control and information in delay-coupled systems: an overview. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2013; 371:20120465. [PMID: 23960223 PMCID: PMC3758166 DOI: 10.1098/rsta.2012.0465] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
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158
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Fischer I, Hsu CC, Gärtner M, Müller C, Overton TW, Thomas OR, Franzreb M. Continuous protein purification using functionalized magnetic nanoparticles in aqueous micellar two-phase systems. J Chromatogr A 2013; 1305:7-16. [DOI: 10.1016/j.chroma.2013.06.011] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2012] [Revised: 06/09/2013] [Accepted: 06/10/2013] [Indexed: 11/28/2022]
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159
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Heiligenthal S, Jüngling T, D'Huys O, Arroyo-Almanza DA, Soriano MC, Fischer I, Kanter I, Kinzel W. Strong and weak chaos in networks of semiconductor lasers with time-delayed couplings. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2013; 88:012902. [PMID: 23944533 DOI: 10.1103/physreve.88.012902] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/05/2012] [Revised: 04/15/2013] [Indexed: 06/02/2023]
Abstract
Nonlinear networks with time-delayed couplings may show strong and weak chaos, depending on the scaling of their Lyapunov exponent with the delay time. We study strong and weak chaos for semiconductor lasers, either with time-delayed self-feedback or for small networks. We examine the dependence on the pump current and consider the question of whether strong and weak chaos can be identified from the shape of the intensity trace, the autocorrelations, and the external cavity modes. The concept of the sub-Lyapunov exponent λ(0) is generalized to the case of two time-scale-separated delays in the system. We give experimental evidence of strong and weak chaos in a network of lasers, which supports the sequence of weak to strong to weak chaos upon monotonically increasing the coupling strength. Finally, we discuss strong and weak chaos for networks with several distinct sub-Lyapunov exponents and comment on the dependence of the sub-Lyapunov exponent on the number of a laser's inputs in a network.
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160
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Lang M, Holzmeier F, Fischer I, Hemberger P. Threshold Photoionization of Fluorenyl, Benzhydryl, Diphenylmethylene, and Their Dimers. J Phys Chem A 2013; 117:5260-8. [DOI: 10.1021/jp403158z] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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161
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Holzmeier F, Lang M, Hader K, Hemberger P, Fischer I. H2CN+ and H2CNH+: New insight into the structure and dynamics from mass-selected threshold photoelectron spectra. J Chem Phys 2013; 138:214310. [DOI: 10.1063/1.4808050] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
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162
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Gottwald M, Schau T, Neuss M, Ridjab D, Fischer I, Butter C, Zaenker M. THU0069 Increased rate of diastolic heart failure in rheumatoid arthritis correlates with systemic inflammation and persistent disease activity, independent from treatment strategy. Ann Rheum Dis 2013. [DOI: 10.1136/annrheumdis-2012-eular.2034] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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163
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Schau T, Gottwald M, Neuss M, Ridjab D, Fischer I, Butter C, Zaenker M. FRI0124 Increased risk of diastolic heart failure in RA – what should we screening for?:. Ann Rheum Dis 2013. [DOI: 10.1136/annrheumdis-2012-eular.2581] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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164
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Fischer KH, Hemberger P, Bodi A, Fischer I. Photoionisation of the tropyl radical. Beilstein J Org Chem 2013; 9:681-8. [PMID: 23616813 PMCID: PMC3629033 DOI: 10.3762/bjoc.9.77] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2013] [Accepted: 03/13/2013] [Indexed: 11/23/2022] Open
Abstract
We present a study on the photoionisation of the cycloheptatrienyl (tropyl) radical, C7H7, using tunable vacuum ultraviolet synchrotron radiation. Tropyl is generated by flash pyrolysis from bitropyl. Ions and electrons are detected in coincidence, permitting us to record mass-selected photoelectron spectra. The threshold photoelectron spectrum of tropyl, corresponding to the X+ 1A1’ ← X2E2” transition, reveals an ionisation energy of 6.23 ± 0.02 eV, in good agreement with Rydberg extrapolations, but slightly lower than the value derived from earlier photoelectron spectra. Several vibrations can be resolved and are reassigned to the C–C stretch mode ν16+ and to a combination of ν16+ with the ring breathing mode ν2+. Above 10.55 eV dissociative photoionisation of tropyl is observed, leading to the formation of C5H5+ and C2H2.
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165
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Herterich J, Zeißner S, Fischer I. Gas-phase-IR and Solid-State Raman Investigation of Paracyclophanes. Z PHYS CHEM 2013. [DOI: 10.1524/zpch.2013.0211] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Abstract
The vibrational structures of three paracyclophanes were investigated, ortho-dihydroxy-[2.2]paracyclophane (o-DHPC), mono-hydroxy[2.2]paracyclophane (MHPC) and 2,11-dithia[3.3]paracyclophane (2SPC). Gas-phase infrared spectroscopy helps to identify the most stable isomer of o-DHPC and MHPC in the gas phase, while FT-Raman spectroscopy was used to study S2PC. For o-DHPC the IR spectrum confirms that the EZ-rotamer dominates, while for MHPC the spectra agree better with the Z-rotamer, but are not unambiguous. The Raman spectrum of 2SPC showed a dominance of the trans isomer in the solid state.
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166
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Soriano MC, Ortín S, Brunner D, Larger L, Mirasso CR, Fischer I, Pesquera L. Optoelectronic reservoir computing: tackling noise-induced performance degradation. OPTICS EXPRESS 2013; 21:12-20. [PMID: 23388891 DOI: 10.1364/oe.21.000012] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
We present improved strategies to perform photonic information processing using an optoelectronic oscillator with delayed feedback. In particular, we study, via numerical simulations and experiments, the influence of a finite signal-to-noise ratio on the computing performance. We illustrate that the performance degradation induced by noise can be compensated for via multi-level pre-processing masks.
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167
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Giegerich J, Fischer I. Photodissociation dynamics of fulvenallene, C7H6. Phys Chem Chem Phys 2013; 15:13162-8. [DOI: 10.1039/c3cp52274a] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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168
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Auerswald J, Engels B, Fischer I, Gerbich T, Herterich J, Krueger A, Lang M, Schmitt HC, Schon C, Walter C. The electronic structure of pyracene: a spectroscopic and computational study. Phys Chem Chem Phys 2013; 15:8151-61. [DOI: 10.1039/c3cp44271c] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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169
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Christen C, Richter M, Fischer I, Eule C, Spiess B, Hatt JM. Unilateral evisceration of an eye following cornea and lens perforation in a sulfur-crested cockatoo (Cacatua galerita). SCHWEIZ ARCH TIERH 2012; 148:615-9. [PMID: 17209511 DOI: 10.1024/0036-7281.148.11.615] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
A 24-year old male sulfur-crested Cockatoo (Cacatua galerita) was presented with a subacute perforation of the cornea without involvement of the lens. The bird was treated conservatively and the eye remained quiescent up to a second traumatic corneal perforation associated with a lens capsule rupture 15 months later. Due to the second perforating trauma of an already blind eye involving the lens, evisceration of the eye was performed. Two months after surgery the cosmetic result was excellent. Treatment options for perforating ocular traumas in captive birds are discussed in detail.
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170
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Fischer I, Morhardt C, Heissler S, Franzreb M. Partitioning behavior of silica-coated nanoparticles in aqueous micellar two-phase systems: evidence for an adsorption-driven mechanism from QCM-D and ATR-FTIR measurements. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2012; 28:15789-15796. [PMID: 23078043 DOI: 10.1021/la303313m] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Quartz crystal microbalance with dissipation (QCM-D), attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), and total organic carbon detection (TOC) are employed to examine the cause of the differences in the partitioning of silica-coated nanoparticles in an aqueous micellar two-phase system based on nonionic surfactant Eumulgin ES. The particles partition into the micelle-rich phase at pH 3 and into the micelle-poor phase at pH 7. Our results clearly show that the nonionic surfactants are adsorbed to the silica surface at pH 3. Above the critical temperature, a stable surfactant bilayer forms on the silica surface. At pH 7, the surfactants do not adsorb to the particle surface; a surfactant-loaded particle is therefore drawn to the micelle-rich phase but otherwise repelled from it. These results suggest that the partitioning in aqueous micellar two-phase systems is mainly driven by hydrogen bonds formed between the surfactants and the component to be partitioned.
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171
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Fischer I, Romano-Clarke G. Association of microtubule-associated protein (MAP1B) with growing axons in cultured hippocampal neurons. Mol Cell Neurosci 2012; 2:39-51. [PMID: 19912782 DOI: 10.1016/1044-7431(91)90038-p] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/1991] [Indexed: 11/19/2022] Open
Abstract
Microtubule-associated protein 1B (MAP1B) is a major constituent of the neuronal cytoskeleton early in development. This protein is present in embryonic brain and is composed of two isoforms that are the result of differential phosphorylation. We examined the distribution of MAP1B during the differentiation of cultured hippocampal neurons and compared it to that of MAP2 and tubulin. We demonstrated by immunofluorescent doublestaining that MAP1B and MAP2 are colocalized in cell bodies and the minor processes of hippocampal neurons during the early stages of development, before the establishment of neuronal polarity. Later, when neurons acquire axonal and dendritic characteristics, MAP1B is sorted into growing axons, including the growth cone, whereas MAP2 is restricted to dendrites and cell bodies. Unlike tubulin, the localization of MAP1B in growing axons is not uniform. Rather, the protein is found concentrated in the distal portion. During later stages of development, the neurons extend a network of fasciculating axonal and dendritic neurites in which the segregation of MAP1B and MAP2 is maintained. However, the staining of MAP1B in mature neuronal cultures decreases in a pattern that resembles the decline of this protein during brain development. These results support the association of MAP1B with growing axons and its correct developmental regulation in the hippocampal culture system.
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172
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Fischer KH, Herterich J, Fischer I, Jaeqx S, Rijs AM. Phenylpropargyl Radicals and Their Dimerization Products: An IR/UV Double Resonance Study. J Phys Chem A 2012; 116:8515-22. [PMID: 22830569 DOI: 10.1021/jp306075a] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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173
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Fischer I, Franzreb M. Magnetische Extraktion - Ein neuartiger Ansatz zur technischen Aufreinigung von Biomolekülen durch magnetische Nanopartikel. CHEM-ING-TECH 2012. [DOI: 10.1002/cite.201250344] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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174
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Steinbauer M, Giegerich J, Fischer KH, Fischer I. The photodissociation dynamics of the ethyl radical, C2H5, investigated by velocity map imaging. J Chem Phys 2012; 137:014303. [DOI: 10.1063/1.4731285] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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175
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Hemberger P, Köhler J, Fischer I, Piani G, Poisson L, Mestdagh JM. Femtosecond dynamics of cyclopropenylidene, c-C3H2. Phys Chem Chem Phys 2012; 14:6173-8. [PMID: 22173743 DOI: 10.1039/c2cp23728h] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The photophysics of the B (1)B(1) state of isolated cyclopropenylidene, c-C(3)H(2), has been studied by femtosecond time-resolved photoionisation and photoelectron spectroscopy. The carbene was produced by flash pyrolysis of 3-chlorocycloprop-1-ene. The bands at 266.9 nm and 264.6 nm have been investigated. The excited state deactivates in a two step process. The first time constant of less than 50 fs corresponds most likely to a nonradiative transition to the A-state, the second one on the order of 200 fs describes the internal conversion to the electronic ground state. The data are compared to those measured for the chlorinated carbene c-C(3)HCl. In the photoelectron spectrum of c-C(3)H(2) resonances were observed which can be assigned to members of a Rydberg d-series.
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176
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D'Huys O, Fischer I, Danckaert J, Vicente R. Spectral and correlation properties of rings of delay-coupled elements: comparing linear and nonlinear systems. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2012; 85:056209. [PMID: 23004845 DOI: 10.1103/physreve.85.056209] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/10/2012] [Indexed: 06/01/2023]
Abstract
The dynamical properties of delay-coupled systems are currently of great interest. So far the analysis has concentrated primarily on identical synchronization properties. Here we study the dynamics of rings of delay-coupled nodes, a topology that cannot show identical synchronization, and compare its properties to those of linear stochastic maps. We find that, in the long delay limit, the correlation functions and spectra of delay-coupled rings of nonlinear systems obey the same scaling laws as linear systems, indicating that important properties of the emerging solution result from network topology.
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177
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Fischer KH, Schneider M, Fischer I, Pfaffinger B, Braunschweig H, Sztáray B, Bodi A. Cover Picture: Bonding in a Borylene Complex Investigated by Photoionization and Dissociative Photoionization (Chem. Eur. J. 15/2012). Chemistry 2012. [DOI: 10.1002/chem.201290055] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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178
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Soriano MC, Van der Sande G, Fischer I, Mirasso CR. Synchronization in simple network motifs with negligible correlation and mutual information measures. PHYSICAL REVIEW LETTERS 2012; 108:134101. [PMID: 22540702 DOI: 10.1103/physrevlett.108.134101] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/24/2011] [Indexed: 05/31/2023]
Abstract
Can different or even identical coupled oscillators be completely uncorrelated and still be synchronized? What can be concluded from the absence of correlations or even mutual information in networks of dynamical elements about their connectivity? These are fundamental and far-reaching questions arising in many complex systems. In this Letter, we address these two questions and demonstrate in simple and generic network motifs that synchronized behavior in the generalized sense can be realized and constructed such that no correlations and even negligible mutual information remain. Our findings raise new questions, in particular, whether and to what extent indirect connections are being underestimated, since the related collective behavior and even synchronization are less likely to be detected.
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179
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Fischer KH, Schneider M, Fischer I, Pfaffinger B, Braunschweig H, Sztáray B, Bodi A. Bonding in a Borylene Complex Investigated by Photoionization and Dissociative Photoionization. Chemistry 2012; 18:4533-40. [DOI: 10.1002/chem.201103993] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2011] [Indexed: 11/11/2022]
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180
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Tiana-Alsina J, Hicke K, Porte X, Soriano MC, Torrent MC, Garcia-Ojalvo J, Fischer I. Zero-lag synchronization and bubbling in delay-coupled lasers. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2012; 85:026209. [PMID: 22463301 DOI: 10.1103/physreve.85.026209] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2011] [Indexed: 05/31/2023]
Abstract
We show experimentally that two semiconductor lasers mutually coupled via a passive relay fiber loop exhibit chaos synchronization at zero lag, and study how this synchronized regime is lost as the lasers' pump currents are increased. We characterize the synchronization properties of the system with high temporal resolution in two different chaotic regimes, namely, low-frequency fluctuations and coherence collapse, identifying significant differences between them. In particular, a marked decrease in synchronization quality develops as the lasers enter the coherence collapse regime. Our high-resolution measurements allow us to establish that synchronization loss is associated with bubbling events, the frequency of which increases with increasing pump current.
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181
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Larger L, Soriano MC, Brunner D, Appeltant L, Gutierrez JM, Pesquera L, Mirasso CR, Fischer I. Photonic information processing beyond Turing: an optoelectronic implementation of reservoir computing. OPTICS EXPRESS 2012; 20:3241-3249. [PMID: 22330562 DOI: 10.1364/oe.20.003241] [Citation(s) in RCA: 215] [Impact Index Per Article: 17.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Many information processing challenges are difficult to solve with traditional Turing or von Neumann approaches. Implementing unconventional computational methods is therefore essential and optics provides promising opportunities. Here we experimentally demonstrate optical information processing using a nonlinear optoelectronic oscillator subject to delayed feedback. We implement a neuro-inspired concept, called Reservoir Computing, proven to possess universal computational capabilities. We particularly exploit the transient response of a complex dynamical system to an input data stream. We employ spoken digit recognition and time series prediction tasks as benchmarks, achieving competitive processing figures of merit.
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182
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Blumenstock G, Fischer I, de Cruppé W, Geraedts M, Selbmann H. Benchmarking in der Patientenversorgung in Deutschland: Aktueller Entwicklungsstand und Perspektiven. GESUNDHEITSOEKONOMIE UND QUALITAETSMANAGEMENT 2012. [DOI: 10.1055/s-0031-1281826] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/14/2022]
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183
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Fischer I. Intraoperative Tremor Monitoring Using Smartphones. BIOMED ENG-BIOMED TE 2012. [DOI: 10.1515/bmt-2012-4277] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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184
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Köhler J, Quast T, Buback J, Fischer I, Brixner T, Nuernberger P, Geiß B, Mager J, Lambert C. Ultrafast charge-transfer dynamics of donor-substituted truxenones. Phys Chem Chem Phys 2012; 14:11081-9. [DOI: 10.1039/c2cp41061c] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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185
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Fischer I, Franzreb M. Nanoparticle Mediated Protein Separation in Aqueous Micellar Two-Phase Systems. SOLVENT EXTRACTION AND ION EXCHANGE 2012. [DOI: 10.1080/07366299.2011.581093] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/14/2022]
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186
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Hemberger P, Bodi A, Schon C, Steinbauer M, Fischer KH, Kaiser C, Fischer I. A pass too far: dissociation of internal energy selected paracyclophane cations, theory and experiment. Phys Chem Chem Phys 2012; 14:11920-9. [DOI: 10.1039/c2cp40905d] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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187
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Oliver N, Soriano MC, Sukow DW, Fischer I. Dynamics of a semiconductor laser with polarization-rotated feedback and its utilization for random bit generation. OPTICS LETTERS 2011; 36:4632-4634. [PMID: 22139266 DOI: 10.1364/ol.36.004632] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Chaotic semiconductor lasers have been proven attractive for fast random bit generation. To follow this strategy, simple robust systems and a systematic approach determining the required dynamical properties and most suitable conditions for this application are needed. We show that dynamics of a single mode laser with polarization-rotated feedback are optimal for random bit generation when characterized simultaneously by a broad power spectrum and low autocorrelation. We observe that successful random bit generation also is sensitive to digitization and postprocessing procedures. Applying the identified criteria, we achieve fast random bit generation rates (up to 4 Gbit/s) with minimal postprocessing.
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188
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Köhler J, Hemberger P, Fischer I, Piani G, Poisson L. Ultrafast Dynamics of Isolated Fluorenone. J Phys Chem A 2011; 115:14249-53. [DOI: 10.1021/jp2073649] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
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189
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Soriano MC, Zunino L, Larger L, Fischer I, Mirasso CR. Distinguishing fingerprints of hyperchaotic and stochastic dynamics in optical chaos from a delayed opto-electronic oscillator. OPTICS LETTERS 2011; 36:2212-2214. [PMID: 21685970 DOI: 10.1364/ol.36.002212] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
In the dynamics of optical systems, one commonly needs to cope with the problem of coexisting deterministic and stochastic components. The separation of these components is an important, although difficult, task. Often the time scales at which determinism and noise dominate the system's dynamics differ. In this Letter we propose to use information-theory-derived quantifiers, more precisely, permutation entropy and statistical complexity, to distinguish between the two behaviors. Based on experiments of a paradigmatic opto-electronic oscillator, we demonstrate that the time scales at which deterministic or noisy behavior dominate can be identified. Supporting numerical simulations prove the accuracy of this identification.
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190
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Hicke K, D'Huys O, Flunkert V, Schöll E, Danckaert J, Fischer I. Mismatch and synchronization: influence of asymmetries in systems of two delay-coupled lasers. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2011; 83:056211. [PMID: 21728634 DOI: 10.1103/physreve.83.056211] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/29/2010] [Indexed: 05/31/2023]
Abstract
We study the synchronization properties of the delay dynamics of two identical semiconductor lasers coupled through a semitransparent mirror. Via an analytical and numerical approach, we investigate the influence of asymmetries, in particular mismatches of self- and cross-coupling strength and differences in self- and cross-coupling delay. We show that the former mismatch affects the stability of the zero-lag state but not the dynamics within the synchronization manifold, while the latter mismatch does not affect the quality of synchronization but alters the dynamics significantly. Our results are extended to different unidirectional coupling schemes. This is highly relevant for communication schemes utilizing chaotic dynamics. Finally, the influence of nonlinear gain saturation on the dynamics and stability of synchronization is discussed.
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191
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D'Huys O, Fischer I, Danckaert J, Vicente R. Role of delay for the symmetry in the dynamics of networks. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2011; 83:046223. [PMID: 21599286 DOI: 10.1103/physreve.83.046223] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/08/2010] [Revised: 12/21/2010] [Indexed: 05/30/2023]
Abstract
The symmetry in a network of oscillators determines the spatiotemporal patterns of activity that can emerge. We study how a delay in the coupling affects symmetry-breaking and -restoring bifurcations. We are able to draw general conclusions in the limit of long delays. For one class of networks we derive a criterion that predicts that delays have a symmetrizing effect. Moreover, we demonstrate that for any network admitting a steady-state solution, a long delay can solely advance the first bifurcation point as compared to the instantaneous-coupling regime.
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192
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Schierholz J, Denk O, Fischer I, Schwarzkopf A. 602 Aerosolized Liposomal Cycloporine (L-Csa) Shows Antimicrobial Activity to Different Opportunistic Microorganism. J Heart Lung Transplant 2011. [DOI: 10.1016/j.healun.2011.01.615] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022] Open
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193
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Pfister J, Schon C, Roth W, Kaiser C, Lambert C, Gruss K, Braunschweig H, Fischer I, Fink RF, Engels B. Paracyclophanes as Model Compounds for Strongly Interacting π-Systems, Part 3: Influence of the Substitution Pattern on Photoabsorption Properties. J Phys Chem A 2011; 115:3583-91. [DOI: 10.1021/jp200823q] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
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194
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Abstract
Abstract
The threshold photoelectron spectrum of NTCDA (1,4,5,8-naphthalene-tetracarboxylic dianhydride) has been recorded using synchrotron radiation. An ionization energy of 9.66 eV was observed. The experiments are supported by DFT computations that yield a value of 9.51 eV, in good agreement with the measured value. Several bands corresponding to excited electronic states of the cation are also visible and can be assigned with the aid of computations.
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195
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Hemberger P, Lang M, Noller B, Fischer I, Alcaraz C, Cunha de Miranda BK, Garcia GA, Soldi-Lose H. Photoionization of Propargyl and Bromopropargyl Radicals: A Threshold Photoelectron Spectroscopic Study. J Phys Chem A 2011; 115:2225-30. [DOI: 10.1021/jp112110j] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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196
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Tellier A, Fischer I, Merino C, Xia H, Camus-Kulandaivelu L, Städler T, Stephan W. Fitness effects of derived deleterious mutations in four closely related wild tomato species with spatial structure. Heredity (Edinb) 2011; 107:189-99. [PMID: 21245893 DOI: 10.1038/hdy.2010.175] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
A key issue in evolutionary biology is an improved understanding of the genetic mechanisms by which species adapt to various environments. Using DNA sequence data, it is possible to quantify the number of adaptive and deleterious mutations, and the distribution of fitness effects of new mutations (its mean and variance) by simultaneously taking into account the demography of a given species. We investigated how selection functions at eight housekeeping genes of four closely related, outcrossing species of wild tomatoes that are native to diverse environments in western South America (Solanum arcanum, S. chilense, S. habrochaites and S. peruvianum). We found little evidence for adaptive mutations but pervasive evidence for strong purifying selection in coding regions of the four species. In contrast, the strength of purifying selection seems to vary among the four species in non-coding (NC) regions (introns). Using F(ST)-based measures of fixation in subdivided populations, we suggest that weak purifying selection has affected the NC regions of S. habrochaites, S. chilense and S. peruvianum. In contrast, NC regions in S. arcanum show a distribution of fitness effects with mutations being either nearly neutral or very strongly deleterious. These results suggest that closely related species with similar genetic backgrounds but experiencing contrasting environments differ in the variance of deleterious fitness effects.
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197
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Steinbauer M, Lang M, Fischer I, de Miranda BKC, Romanzin C, Alcaraz C. The photoionisation of propargylene and diazopropyne. Phys Chem Chem Phys 2011; 13:17956-9. [DOI: 10.1039/c1cp22265a] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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198
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Schon C, Roth W, Fischer I, Pfister J, Fink RF, Engels B. Paracyclophanes as model compounds for strongly interacting π-systems. Part 2: mono-hydroxy[2.2]paracyclophane. Phys Chem Chem Phys 2011; 13:11076-82. [DOI: 10.1039/c0cp02841j] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
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199
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Steinbauer M, Hemberger P, Fischer I, Bodi A. Photoionization of C7H6 and C7H5: Observation of the Fulvenallenyl Radical. Chemphyschem 2010; 12:1795-7. [DOI: 10.1002/cphc.201000892] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2010] [Indexed: 11/09/2022]
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200
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D'Huys O, Vicente R, Danckaert J, Fischer I. Amplitude and phase effects on the synchronization of delay-coupled oscillators. CHAOS (WOODBURY, N.Y.) 2010; 20:043127. [PMID: 21198097 DOI: 10.1063/1.3518363] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
We consider the behavior of Stuart-Landau oscillators as generic limit-cycle oscillators when they are interacting with delay. We investigate the role of amplitude and phase instabilities in producing symmetry-breaking/restoring transitions. Using analytical and numerical methods we compare the dynamics of one oscillator with delayed feedback, two oscillators mutually coupled with delay, and two delay-coupled elements with self-feedback. Taking only the phase dynamics into account, no chaotic dynamics is observed, and the stability of the identical synchronization solution is the same in each of the three studied networks of delay-coupled elements. When allowing for a variable oscillation amplitude, the delay can induce amplitude instabilities. We provide analytical proof that, in case of two mutually coupled elements, the onset of an amplitude instability always results in antiphase oscillations, leading to a leader-laggard behavior in the chaotic regime. Adding self-feedback with the same strength and delay as the coupling stabilizes the system in the transverse direction and, thus, promotes the onset of identically synchronized behavior.
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