@unpublished{Popivanov2004, author = {Popivanov, Petăr R.}, title = {Lorenz transformations and creation of logarithmic singularities to the solutions of some nonstrictly hyperbolic semilinear systems with two space variables}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-26710}, year = {2004}, language = {en} } @unpublished{PolkovnikovTarkhanov2017, author = {Polkovnikov, Alexander and Tarkhanov, Nikolai Nikolaevich}, title = {A Riemann-Hilbert problem for the Moisil-Teodorescu system}, volume = {6}, number = {3}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-397036}, pages = {31}, year = {2017}, abstract = {In a bounded domain with smooth boundary in R^3 we consider the stationary Maxwell equations for a function u with values in R^3 subject to a nonhomogeneous condition (u,v)_x = u_0 on the boundary, where v is a given vector field and u_0 a function on the boundary. We specify this problem within the framework of the Riemann-Hilbert boundary value problems for the Moisil-Teodorescu system. This latter is proved to satisfy the Shapiro-Lopaniskij condition if an only if the vector v is at no point tangent to the boundary. The Riemann-Hilbert problem for the Moisil-Teodorescu system fails to possess an adjoint boundary value problem with respect to the Green formula, which satisfies the Shapiro-Lopatinskij condition. We develop the construction of Green formula to get a proper concept of adjoint boundary value problem.}, language = {en} } @unpublished{PikovskijZaksFeudeletal.1995, author = {Pikovskij, Arkadij and Zaks, Michael A. and Feudel, Ulrike and Kurths, J{\"u}rgen}, title = {Singular continuous spectra in dissipative dynamics}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-13787}, year = {1995}, abstract = {We demonstrate the occurrence of regimes with singular continuous (fractal) Fourier spectra in autonomous dissipative dynamical systems. The particular example in an ODE system at the accumulation points of bifurcation sequences associated to the creation of complicated homoclinic orbits. Two different machanisms responsible for the appearance of such spectra are proposed. In the first case when the geometry of the attractor is symbolically represented by the Thue-Morse sequence, both the continuous-time process and its descrete Poincar{\´e} map have singular power spectra. The other mechanism owes to the logarithmic divergence of the first return times near the saddle point; here the Poincar{\´e} map possesses the discrete spectrum, while the continuous-time process displays the singular one. A method is presented for computing the multifractal characteristics of the singular continuous spectra with the help of the usual Fourier analysis technique.}, language = {en} } @unpublished{PikovskijFeudel1994, author = {Pikovskij, Arkadij and Feudel, Ulrike}, title = {Characterizing strange nonchaotic attractors}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-13405}, year = {1994}, abstract = {Strange nonchaotic attractors typically appear in quasiperiodically driven nonlinear systems. Two methods of their characterization are proposed. The first one is based on the bifurcation analysis of the systems, resulting from periodic approximations of the quasiperiodic forcing. Secondly, we propose th characterize their strangeness by calculating a phase sensitivity exponent, that measures the sensitivity with respect to changes of the phase of the external force. It is shown, that phase sensitivity appears if there is a non-zero probability for positive local Lyapunov exponents to occur.}, language = {en} } @unpublished{Pikovskij2015, author = {Pikovskij, Arkadij}, title = {Comment on "Asymptotic Phase for Stochastic Oscillators"}, series = {Physical review letters}, volume = {115}, journal = {Physical review letters}, number = {6}, publisher = {American Physical Society}, address = {College Park}, issn = {0031-9007}, doi = {10.1103/PhysRevLett.115.069401}, pages = {1}, year = {2015}, language = {en} } @unpublished{PfaeffleStephan2012, author = {Pf{\"a}ffle, Frank and Stephan, Christoph A.}, title = {On gravity, torsion and the spectral action principle}, issn = {2193-6943}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-59989}, year = {2012}, abstract = {We consider compact Riemannian spin manifolds without boundary equipped with orthogonal connections. We investigate the induced Dirac operators and the associated commutative spectral triples. In case of dimension four and totally anti-symmetric torsion we compute the Chamseddine-Connes spectral action, deduce the equations of motions and discuss critical points.}, language = {en} } @unpublished{PfaeffleStephan2012, author = {Pf{\"a}ffle, Frank and Stephan, Christoph A.}, title = {The Holst action by the spectral action principle}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-60032}, year = {2012}, abstract = {We investigate the Holst action for closed Riemannian 4-manifolds with orthogonal connections. For connections whose torsion has zero Cartan type component we show that the Holst action can be recovered from the heat asymptotics for the natural Dirac operator acting on left-handed spinor fields.}, language = {en} } @unpublished{PfaeffleStephan2012, author = {Pf{\"a}ffle, Frank and Stephan, Christoph A.}, title = {Chiral asymmetry and the spectral action}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-60046}, year = {2012}, abstract = {We consider orthogonal connections with arbitrary torsion on compact Riemannian manifolds. For the induced Dirac operators, twisted Dirac operators and Dirac operators of Chamseddine-Connes type we compute the spectral action. In addition to the Einstein-Hilbert action and the bosonic part of the Standard Model Lagrangian we find the Holst term from Loop Quantum Gravity, a coupling of the Holst term to the scalar curvature and a prediction for the value of the Barbero-Immirzi parameter.}, language = {en} } @unpublished{PetrocziBackhouseBarkoukisetal.2015, author = {Petroczi, Andrea and Backhouse, Susan H. and Barkoukis, Vassilis and Brand, Ralf and Elbe, Anne-Marie and Lazuras, Larnbros and Lucidi, Fabio}, title = {A call for policy guidance on psychometric testing in doping control in sport}, series = {International journal of drug policy}, volume = {26}, journal = {International journal of drug policy}, number = {11}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0955-3959}, doi = {10.1016/j.drugpo.2015.04.022}, pages = {1130 -- 1139}, year = {2015}, abstract = {One of the fundamental challenges in anti-doping is identifying athletes who use, or are at risk of using, prohibited performance enhancing substances. The growing trend to employ a forensic approach to doping control aims to integrate information from social sciences (e.g., psychology of doping) into organised intelligence to protect clean sport. Beyond the foreseeable consequences of a positive identification as a doping user, this task is further complicated by the discrepancy between what constitutes a doping offence in the World Anti-Doping Code and operationalized in doping research. Whilst psychology plays an important role in developing our understanding of doping behaviour in order to inform intervention and prevention, its contribution to the array of doping diagnostic tools is still in its infancy. In both research and forensic settings, we must acknowledge that (1) socially desirable responding confounds self-reported psychometric test results and (2) that the cognitive complexity surrounding test performance means that the response-time based measures and the lie detector tests for revealing concealed life-events (e.g., doping use) are prone to produce false or non-interpretable outcomes in field settings. Differences in social-cognitive characteristics of doping behaviour that are tested at group level (doping users vs. non-users) cannot be extrapolated to individuals; nor these psychometric measures used for individual diagnostics. In this paper, we present a position statement calling for policy guidance on appropriate use of psychometric assessments in the pursuit of clean sport. We argue that, to date, both self-reported and response-time based psychometric tests for doping have been designed, tested and validated to explore how athletes feel and think about doping in order to develop a better understanding of doping behaviour, not to establish evidence for doping. A false 'positive' psychological profile for doping affects not only the individual 'clean' athlete but also their entourage, their organisation and sport itself. The proposed policy guidance aims to protect the global athletic community against social, ethical and legal consequences from potential misuse of psychological tests, including erroneous or incompetent applications as forensic diagnostic tools in both practice and research. (C) 2015 Elsevier B.V. All rights reserved.}, language = {en} } @unpublished{PetrocziBackhouseBarkoukisetal.2015, author = {Petroczi, Andrea and Backhouse, Susan H. and Barkoukis, Vassilis and Brand, Ralf and Elbe, Anne-Marie and Lazuras, Lambros and Lucidi, Fabio}, title = {A matter of mind-set in the interpretation of forensic application}, series = {International journal of drug policy}, volume = {26}, journal = {International journal of drug policy}, number = {11}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0955-3959}, doi = {10.1016/j.drugpo.2015.06.007}, pages = {1142 -- 1143}, year = {2015}, language = {en} }