Refine
Year of publication
Document Type
- Preprint (230) (remove)
Language
- English (230) (remove)
Is part of the Bibliography
- yes (230) (remove)
Keywords
- mental number line (4)
- numerical cognition (4)
- Cauchy problem (3)
- Fredholm property (3)
- index (3)
- reciprocal class (3)
- Brownian motion (2)
- Climate change (2)
- Dirac operator (2)
- Gibbs measure (2)
- Heat equation (2)
- Lefschetz number (2)
- Navier-Stokes equations (2)
- Perturbed complexes (2)
- Riemann-Hilbert problem (2)
- Riemannian manifold (2)
- Stochastic Differential Equation (2)
- Toeplitz operators (2)
- attention (2)
- birth-death-mutation-competition point process (2)
- cluster expansion (2)
- counting process (2)
- curvature (2)
- hard core potential (2)
- local time (2)
- p-Laplace operator (2)
- reversible measure (2)
- singular perturbation (2)
- skew Brownian motion (2)
- spatial cognition (2)
- star product (2)
- stochastic differential equations (2)
- 2AFC (1)
- Adaptive evolution (1)
- Air showers (1)
- Alan Kennedy (1)
- Anti-doping (1)
- Artificial selection (1)
- Athlete (1)
- Attitude (1)
- Averaging principle (1)
- Betriebssysteme (1)
- Bose-Einstein condensation (1)
- Botanic gardens (1)
- Boundary value methods (1)
- Boundary value problems for first order systems (1)
- Brownian bridge (1)
- Brownian motion with discontinuous drift (1)
- CCR-algebra (1)
- Canonical Gibbs measure (1)
- Carleman formulas (1)
- Carrera Digital D132 (1)
- Cauchy data spaces (1)
- Censoring (1)
- Cherenkov Telescopes (1)
- Clifford algebra (1)
- Climate variability (1)
- Clonal plants (1)
- Cross-effects (1)
- Database (1)
- Decoupling (1)
- Delphi study (1)
- Dirac-type operator (1)
- Dirichlet form (1)
- Dirichlet problem (1)
- Dirichlet-to-Neumann operator (1)
- Dispersal (1)
- Drug (1)
- Duality formula (1)
- Echtzeit (1)
- Ecosystem function (1)
- Editorial policies (1)
- Eigenvalues (1)
- Elliptic operators (1)
- Erfahrungsbericht (1)
- Euler equations (1)
- Euler-Lagrange equations (1)
- Evidence-based policy making (1)
- Ex situ conservation (1)
- Extremal problem (1)
- Eye movements (1)
- Eyemind assumption (1)
- Feynman-Kac formula (1)
- Finite difference method (1)
- Fischer-Riesz equations (1)
- Fourth order Sturm-Liouville problem (1)
- Fredholm operator (1)
- Fredholm operators (1)
- Functional diversity (1)
- Functional traits (1)
- Genetic drift (1)
- Gibbs point processes (1)
- Gibbs state (1)
- Green formula (1)
- Green's operator (1)
- Hodge theory (1)
- Hypoelliptic operators (1)
- Hölder-type source condition (1)
- Infinite-dimensional SDE (1)
- Knowledge creep (1)
- Knowledge utilization (1)
- Kolmogorov-Smirnov type tests (1)
- LEGO Mindstorms EV3 (1)
- Lagrangian system (1)
- Lamé system (1)
- Land use (1)
- Landscape (1)
- Laplace-Beltrami operator (1)
- Levy process (1)
- Liouville theorem (1)
- Lipschitz domains (1)
- Logrank test (1)
- Loop space (1)
- Lévy diffusion approximation (1)
- Lévy diffusions on manifolds (1)
- Lévy measure (1)
- Lévy type processes (1)
- MHD-equations (1)
- Malliavin calculus (1)
- Management (1)
- Markov chain (1)
- Markov-field property (1)
- Martin-Dynkin boundary (1)
- Modality (1)
- Modelling (1)
- Montel theorem (1)
- Morse-Smale property (1)
- Neumann problem (1)
- Newton method (1)
- Non-proportional hazards (1)
- Numerov's method (1)
- Operators on manifolds with second order singularities (1)
- Organizational epistemology (1)
- Orthoptera (1)
- Peano phenomena (1)
- Planetary Rings (1)
- Plant growth (1)
- Point process (1)
- Prohibited performance enhancement (1)
- Proportional hazards (1)
- Punctuated equilibrium theory (1)
- Quasilinear equations (1)
- ROC curve (1)
- RT_PREEMT patch (1)
- RT_PREEMT-Patch (1)
- Reading (1)
- Renormalized integral (1)
- Runge-Kutta methods (1)
- SNARC (1)
- SNARC effect (1)
- Scene perception (1)
- Schrödinger problem (1)
- Serial and parallel (1)
- Skorokhod' s invariance principle (1)
- Statistics (1)
- Sturm-Liouville problems (1)
- TOP-Guidelines (1)
- TeV gamma-ray astronomy (1)
- Two-level interacting process (1)
- Two-sample tests (1)
- Vitali theorem (1)
- WKB method (1)
- Wasserstein distance (1)
- Wave operator (1)
- Wiener measure (1)
- absorbing boundary (1)
- aggression (1)
- analytic continuation (1)
- ancient DNA (1)
- anniversary issue (1)
- applied classical electromagnetism (1)
- approximate inertial manifolds (1)
- asymptotic expansion (1)
- asymptotic methods (1)
- asymptotics (1)
- automatic processing (1)
- boundary layer (1)
- boundary regularity (1)
- boundary value problems (1)
- bridge (1)
- bridges of random walks (1)
- calculus of variations (1)
- canonical Marcus integration (1)
- characteristic boundary point (1)
- characteristic points (1)
- children (1)
- classical solution (1)
- climatic limitation (1)
- coercivity (1)
- completeness (1)
- composition operator (1)
- compound Poisson processes (1)
- compound detection or discrimination (1)
- conditional Wiener measure (1)
- conjugate gradient (1)
- continuity in Sobolev spaces with double weights (1)
- continuous time Markov chain (1)
- coupling methods (1)
- cross-cultural (1)
- cusp (1)
- dating (1)
- dbar-Neumann problem (1)
- decay of eigenfunctions (1)
- decomposition (1)
- definition (1)
- derivational affixes (1)
- design options (1)
- detailed balance equation (1)
- determinantal point processes (1)
- developmental dyscalculia (1)
- discontinuous Robin condition (1)
- distorted Brownian motion (1)
- division of spaces (1)
- duality formula (1)
- dynamical system (1)
- ecophysiology (1)
- edge quantizations (1)
- eingebettete Systeme (1)
- elliptic boundary conditions (1)
- elliptic complex (1)
- elliptic complexes (1)
- ellipticity with parameter (1)
- embedded systems (1)
- embodied cognition (1)
- embodied numerical cognition (1)
- empirical Wasserstein distance (1)
- enlargement of filtration (1)
- environmental policy (1)
- equivalence (1)
- evolution equation (1)
- exact simulation (1)
- exact simulation method (1)
- experience report (1)
- experiment (1)
- experiments (1)
- finsler distance (1)
- first boundary value problem (1)
- fixed point formula (1)
- fluctuation phenomena (1)
- foliated diffusion (1)
- gender (1)
- generalized Laplace operator (1)
- geographical and altitudinal distribution (1)
- germination (1)
- gestures (1)
- globally hyperbolic spacetime (1)
- goodness-of-fit (1)
- heat equation (1)
- heavy-tailed distributions (1)
- hitting times (1)
- host-parasite stochastic particle system (1)
- human evolutionary genetics (1)
- hyperbolic dynamical system (1)
- hypoelliptic estimate (1)
- ill-posed problems (1)
- index of stability (1)
- infinite divisibility (1)
- infinite-dimensional Brownian diffusion (1)
- infinitely divisible point processes (1)
- innate number sense (1)
- integral formulas (1)
- integral representation method (1)
- integration by parts on path space (1)
- interaction matrix (1)
- invariant (1)
- invasive (1)
- jump process (1)
- jump processes (1)
- kernel method (1)
- lattice packing and covering (1)
- lattice point (1)
- learning disability (1)
- literature review (1)
- logarithmic residue (1)
- long-term policy (1)
- m-commerce (1)
- manifold with boundary (1)
- mapping degree (1)
- marriage (1)
- mathematical cognition (1)
- mating (1)
- mechanical effects of light (1)
- media violence (1)
- mediation (1)
- minimax convergence rates (1)
- minimax rate (1)
- mixed problems (1)
- mobile commerce research (1)
- model selection (1)
- molecular motor (1)
- morphological processing (1)
- multiplicative Lévy noise (1)
- multiplicative noise (1)
- mycorrhiza (1)
- nitrogen fixation (1)
- noise (1)
- non-Markov drift (1)
- non-linear integro-differential equations (1)
- non-native speakers (1)
- non-probability samples (1)
- non-regular drift (1)
- non-uniqueness (1)
- nonlinear equations (1)
- nonlinear semigroup (1)
- nonparametric regression (1)
- nonsmooth curves (1)
- number line (1)
- numeracy training (1)
- observational data (1)
- occupational gender segregation (1)
- operating systems (1)
- operational momentum (1)
- p-Laplace Operator (1)
- palaeogenomics (1)
- parasites and diseases (1)
- partial least squares (1)
- partnership (1)
- path integral (1)
- periodic Gaussian process (1)
- periodic Ornstein-Uhlenbeck process (1)
- permanental- (1)
- polyhedra and polytopes (1)
- porous medium equation (1)
- probability summation (1)
- pseudodifferential operator (1)
- psychometric functions (1)
- quasilinear Fredholm operator (1)
- quasilinear equation (1)
- random number generation (1)
- random processes (1)
- random walk (1)
- random walk on Abelian group (1)
- random walks on graphs (1)
- real-time (1)
- reciprocal characteristics (1)
- reciprocal processes (1)
- redundancy gain (1)
- regular figures (1)
- regularisation (1)
- regularization (1)
- regularization methods (1)
- rejection sampling (1)
- removable set (1)
- removable sets (1)
- reproducing kernel Hilbert space (1)
- reproductive biology (1)
- response selection (1)
- root functions (1)
- semi-classical difference operator (1)
- semipermeable barriers (1)
- singular drifts (1)
- singular integral equations (1)
- singular point (1)
- skew diffusion (1)
- small noise asymptotic (1)
- socialization effects (1)
- soils (1)
- spatial numerical associations (1)
- spatial-nunmerical association (1)
- specific entropy (1)
- spectral kernel function (1)
- spectral theorem (1)
- spirallike function (1)
- stable limit cycle (1)
- statistical inverse problem (1)
- statistical model selection (1)
- step process (1)
- stereotypes (1)
- stochastic bridge (1)
- stochastic bridges (1)
- stopping rules (1)
- strongly pseudoconvex domains (1)
- symbolic calculation (1)
- symplectic manifold (1)
- the Dirichlet problem (1)
- the first boundary value problem (1)
- time duality (1)
- time series (1)
- time series with heavy tails (1)
- trace (1)
- tunneling (1)
- two-level interacting processes (1)
- variational principle (1)
- visual perception (1)
- weak boundary values (1)
- weighted Hölder spaces (1)
- zero-noise limit (1)
Institute
- Institut für Mathematik (87)
- Interdisziplinäres Zentrum für Dynamik komplexer Systeme (25)
- Institut für Physik und Astronomie (24)
- Institut für Anglistik und Amerikanistik (18)
- Institut für Biochemie und Biologie (18)
- Department Psychologie (17)
- Institut für Geowissenschaften (17)
- Institut für Chemie (7)
- Extern (6)
- Department Sport- und Gesundheitswissenschaften (5)
This is an introduction to Wiener measure and the Feynman-Kac formula on general Riemannian manifolds for Riemannian geometers with little or no background in stochastics. We explain the construction of Wiener measure based on the heat kernel in full detail and we prove the Feynman-Kac formula for Schrödinger operators with bounded potentials. We also consider normal Riemannian coverings and show that projecting and lifting of paths are inverse operations which respect the Wiener measure.
Many perceptual and cognitive tasks permit or require the integrated cooperation of specialized sensory channels, detectors, or other functionally separate units. In compound detection or discrimination tasks, 1 prominent general mechanism to model the combination of the output of different processing channels is probability summation. The classical example is the binocular summation model of Pirenne (1943), according to which a weak visual stimulus is detected if at least 1 of the 2 eyes detects this stimulus; as we review briefly, exactly the same reasoning is applied in numerous other fields. It is generally accepted that this mechanism necessarily predicts performance based on 2 (or more) channels to be superior to single channel performance, because 2 separate channels provide "2 chances" to succeed with the task. We argue that this reasoning is misleading because it neglects the increased opportunity with 2 channels not just for hits but also for false alarms and that there may well be no redundancy gain at all when performance is measured in terms of receiver operating characteristic curves. We illustrate and support these arguments with a visual detection experiment involving different spatial uncertainty conditions. Our arguments and findings have important implications for all models that, in one way or another, rest on, or incorporate, the notion of probability summation for the analysis of detection tasks, 2-alternative forced-choice tasks, and psychometric functions.
We define weak boundary values of solutions to those nonlinear differential equations which appear as Euler-Lagrange equations of variational problems. As a result we initiate the theory of Lagrangian boundary value problems in spaces of appropriate smoothness. We also analyse if the concept of mapping degree of current importance applies to the study of Lagrangian problems.
Projection methods based on wavelet functions combine optimal convergence rates with algorithmic efficiency. The proofs in this paper utilize the approximation properties of wavelets and results from the general theory of regularization methods. Moreover, adaptive strategies can be incorporated still leading to optimal convergence rates for the resulting algorithms. The so-called wavelet-vaguelette decompositions enable the realization of especially fast algorithms for certain operators.
Preclinical work indicates that calcitriol restores vascular function by normalizing the endothelial expression of cyclooxygenase-2 and thromboxane-prostanoid receptors in conditions of estrogen deficiency and thus prevents the thromboxane-prostanoid receptor activation-induced inhibition of nitric oxide synthase. Since endothelial dysfunction is a key factor in the pathogenesis of cardiovascular diseases, this finding may have an important translational impact. It provides a clear rationale to use endothelial function in clinical trials aiming to find the optimal dose of vitamin D for the prevention of cardiovascular events in postmenopausal women.
Untitled
(2011)
We analyze a general class of difference operators containing a multi-well potential and a small parameter. We decouple the wells by introducing certain Dirichlet operators on regions containing only one potential well, and we treat the eigenvalue problem as a small perturbation of these comparison problems. We describe tunneling by a certain interaction matrix similar to the analysis for the Schrödinger operator, and estimate the remainder, which is exponentially small and roughly quadratic compared with the interaction matrix.
This article assesses the distance between the laws of stochastic differential equations with multiplicative Lévy noise on path space in terms of their characteristics. The notion of transportation distance on the set of Lévy kernels introduced by Kosenkova and Kulik yields a natural and statistically tractable upper bound on the noise sensitivity. This extends recent results for the additive case in terms of coupling distances to the multiplicative case. The strength of this notion is shown in a statistical implementation for simulations and the example of a benchmark time series in paleoclimate.
Think local sell global
(2010)
The role of knowledge in the policy process remains a central theoretical puzzle in policy analysis and political science. This article argues that an important yet missing piece of this puzzle is the systematic exploration of the political use of policy knowledge. While much of the recent debate has focused on the question of how the substantive use of knowledge can improve the quality of policy choices, our understanding of the political use of knowledge and its effects in the policy process has remained deficient in key respects. A revised conceptualization of the political use of knowledge is introduced that emphasizes how conflicting knowledge can be used to contest given structures of policy authority. This allows the analysis to differentiate between knowledge creep and knowledge shifts as two distinct types of knowledge effects in the policy process. While knowledge creep is associated with incremental policy change within existing policy structures, knowledge shifts are linked to more fundamental policy change in situations when the structures of policy authority undergo some level of transformation. The article concludes by identifying characteristics of the administrative structure of policy systems or sectors that make knowledge shifts more or less likely.
When trying to extend the Hodge theory for elliptic complexes on compact closed manifolds to the case of compact manifolds with boundary one is led to a boundary value problem for
the Laplacian of the complex which is usually referred to as Neumann problem. We study the Neumann problem for a larger class of sequences of differential operators on
a compact manifold with boundary. These are sequences of small curvature, i.e., bearing the property that the composition of any two neighbouring operators has order less than two.
We develop the method of Fischer-Riesz equations for general boundary value problems elliptic in the sense of Douglis-Nirenberg. To this end we reduce them to a boundary problem for a (possibly overdetermined) first order system whose classical symbol has a left inverse. For such a problem there is a uniquely determined boundary value problem which is adjoint to the given one with respect to the Green formula. On using a well elaborated theory of approximation by solutions of the adjoint problem, we find the Cauchy data of solutions of our problem.
For a sequence of Hilbert spaces and continuous linear operators the curvature is defined to be the composition of any two consecutive operators. This is modeled on the de Rham resolution of a connection on a module over an algebra. Of particular interest are those sequences for which the curvature is "small" at each step, e.g., belongs to a fixed operator ideal. In this context we elaborate the theory of Fredholm sequences and show how to introduce the Lefschetz number.
The dynamics of tail-like current sheets under the influence of small-scale plasma turbulence
(1999)
A 2D-magnetohydrodynamic model of current-sheet dynamics caused by anomalous electrical resistivity as result of small-scale plasma turbulence is proposed. The anomalous resistivity is assumed to be proportional to the square of the gradient of the magnetic pressure as may be valid for instance in the case of lower-hybrid-drift turbulence. The initial resistivity pulse is given. Then the temporal and spatial evolution of the magnetic and electric fields, plasma density, pressure, convection and resistivity are considered. The motion of the induced electric field is discussed as indicator of the plasma disturbances. The obtained results found using much improved numerical methods show a magnetic field evolution with x-line formation and plasma acceleration. Besides, in the current sheet, three types of magnetohydrodynamic waves occur, fast magnetoacoustic waves of compression and rarefaction as well as slow magnetoacoustic waves.
Language processing changes with the knowledge and use of two languages. The advantage of being bilingual comes at the expense of increased processing demands and processing costs. I suggest considering bilingual complexity including these demands and costs. The proposed model claims effortless monolingual processing. By integrating individual and situational variability, the model would lose its idealistic touch, even for monolinguals.
The two and k-sample tests of equality of the survival distributions against the alternatives including cross-effects of survival functions, proportional and monotone hazard ratios, are given for the right censored data. The asymptotic power against approaching alternatives is investigated. The tests are applied to the well known chemio and radio therapy data of the Gastrointestinal Tumor Study Group. The P-values for both proposed tests are much smaller then in the case of other known tests. Differently from the test of Stablein and Koutrouvelis the new tests can be applied not only for singly but also to randomly censored data.
We introduce a theoretical framework for performing statistical hypothesis testing simultaneously over a fairly general, possibly uncountably infinite, set of null hypotheses. This extends the standard statistical setting for multiple hypotheses testing, which is restricted to a finite set. This work is motivated by numerous modern applications where the observed signal is modeled by a stochastic process over a continuum. As a measure of type I error, we extend the concept of false discovery rate (FDR) to this setting. The FDR is defined as the average ratio of the measure of two random sets, so that its study presents some challenge and is of some intrinsic mathematical interest. Our main result shows how to use the p-value process to control the FDR at a nominal level, either under arbitrary dependence of p-values, or under the assumption that the finite dimensional distributions of the p-value process have positive correlations of a specific type (weak PRDS). Both cases generalize existing results established in the finite setting, the latter one leading to a less conservative procedure. The interest of this approach is demonstrated in several non-parametric examples: testing the mean/signal in a Gaussian white noise model, testing the intensity of a Poisson process and testing the c.d.f. of i.i.d. random variables. Conceptually, an interesting feature of the setting advocated here is that it focuses directly on the intrinsic hypothesis space associated with a testing model on a random process, without referring to an arbitrary discretization.
In this paper an analysis of the excitation conditions of mirror waves is done, which propagate parallel to an external magnetic field. There are found analytical expressions for the dispersion relations of the waves in case of different plasma conditions. These relations may be used in future to develop the nonlinear theory of mirror waves. In comparison with former analytical works, in the study the inuence of the magnetic field and nite temperatures of the ions parallel to the magnetic field are taken into account. Application is done for the earth's magnetosheath.
Estimation and testing of distributions in metric spaces are well known. R.A. Fisher, J. Neyman, W. Cochran and M. Bartlett achieved essential results on the statistical analysis of categorical data. In the last 40 years many other statisticians found important results in this field. Often data sets contain categorical data, e.g. levels of factors or names. There does not exist any ordering or any distance between these categories. At each level there are measured some metric or categorical values. We introduce a new method of scaling based on statistical decisions. For this we define empirical probabilities for the original observations and find a class of distributions in a metric space where these empirical probabilities can be found as approximations for equivalently defined probabilities. With this method we identify probabilities connected with the categorical data and probabilities in metric spaces. Here we get a mapping from the levels of factors or names into points of a metric space. This mapping yields the scale for the categorical data. From the statistical point of view we use multivariate statistical methods, we calculate maximum likelihood estimations and compare different approaches for scaling.
Special issue on graph transformation and visual modeling techniques - guest editors' introduction
(2013)
A linear differential operator L is called weakly hypoelliptic if any local solution u of Lu = 0 is smooth. We allow for systems, i.e. the coefficients may be matrices, not necessarily of square size. This is a huge class of important operators which covers all elliptic, overdetermined elliptic, subelliptic and parabolic equations. We extend several classical theorems from complex analysis to solutions of any weakly hypoelliptic equation: the Montel theorem providing convergent subsequences, the Vitali theorem ensuring convergence of a given sequence, and Riemann's first removable singularity theorem. In the case of constant coefficients we show that Liouville's theorem holds, any bounded solution must be constant and any L^p solution must vanish.
We develop a new approach to the analysis of pseudodifferential operators with small parameter 'epsilon' in (0,1] on a compact smooth manifold X. The standard approach assumes action of operators in Sobolev spaces whose norms depend on 'epsilon'. Instead we consider the cylinder [0,1] x X over X and study pseudodifferential operators on the cylinder which act, by the very nature, on functions depending on 'epsilon' as well. The action in 'epsilon' reduces to multiplication by functions of this variable and does not include any differentiation. As but one result we mention asymptotic of solutions to singular perturbation problems for small values of 'epsilon'.
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 Poincaré map have singular power spectra. The other mechanism owes to the logarithmic divergence of the first return times near the saddle point; here the Poincaré 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.
Simplicity is a mindset, a way of looking at solutions, an extremely wide-ranging philosophical stance on the world, and thus a deeply rooted cultural paradigm. The culture of "less" can be profoundly disruptive, cutting out existing "standard" elements from products and business models, thereby revolutionizing entire markets.
Should I stay or should I go - The challenges and opportunities of moving between University systems
(2014)
Serial and parallel processes in eye movement control - current controversies and future directions
(2013)
In this editorial for the Special Issue on Serial and Parallel Processing in Reading we explore the background to the current debate concerning whether the word recognition processes in reading are strictly serialsequential or take place in an overlapping parallel fashion. We consider the history of the controversy and some of the underlying assumptions, together with an analysis of the types of evidence and arguments that have been adduced to both sides of the debate, concluding that both accounts necessarily presuppose some weakening of, or elasticity in, the eyemind assumption. We then consider future directions, both for reading research and for scene viewing, and wrap up the editorial with a brief overview of the following articles and their conclusions.
This essay reads Sam Selvon’s novel The Lonely Londoners (1956) as a milestone in the decolonisation of British fiction. After an introduction to Selvon and the core composition of the novel, it discusses the ways in which the narrative takes on issues of race and racism, how it in the tradition of the Trinidadian carnival confronts audiences with sexual profanation and black masculine swagger, and not least how the novel, especially through its elaborate use of creole Englishes, reimagines London as a West Indian metropolis. The essay then turns more systematically to the ways in which Selvon translates Western literary models and their isolated subject positions into collective modes of narrative performance taken from Caribbean orature and the calypsonian tradition. The Lonely Londoners breathes entirely new life into the ossified conventions of the English novel, and imbues it with unforeseen aesthetic, ethical, political and epistemological possibilities.
Two deterministic processes leading to roughening interfaces are considered. It is shown that the dynamics of linear perturbations of turbulent regimes in coupled map lattices is governed by a discrete version of the Kardar-Parisi-Zhang equation. The asymptotic scaling behavior of the perturbation field is investigated in the case of large lattices. Secondly, the dynamics of an order-disorder interface is modelled with a simple two-dimensional coupled map lattice, possesing a turbulent and a laminar state. It is demonstrated, that in some range of parameters the spreading of the turbulent state is accompanied by kinetic roughening of the interface.
This commentary argues that, rather than providing an "exhaustive review," Elson and Ferguson (2013) discuss a selective sample of empirical studies on violent video game use which corroborate their claim that there is no systematic evidence for a link between violent video game play and aggression. In evaluating the evidence, the authors portray a biased picture of the current state of knowledge about media violence effects. They fail to distinguish between aggression and violence and between everyday and clinical forms of aggression. Furthermore, they misrepresent key constructs, such as mediation, moderation, and external validity, to discredit methodologies used to assess aggression and media violence use. The paper moves the debate backward rather than forward, falling behind existing meta-analytic studies that consider a much wider and more balanced range of studies.
Heterocystous cyanobacteria of the genus Nodularia form extensive blooms in the Baltic Sea and contribute substantially to the total annual primary production. Moreover, they dispense a large fraction of new nitrogen to the ecosystem when inorganic nitrogen concentration in summer is low. Thus, it is of ecological importance to know how Nodularia will react to future environmental changes, in particular to increasing carbon dioxide (CO2) concentrations and what consequences there might arise for cycling of organic matter in the Baltic Sea. Here, we determined carbon (C) and dinitrogen (N-2) fixation rates, growth, elemental stoichiometry of particulate organic matter and nitrogen turnover in batch cultures of the heterocystous cyanobacterium Nodularia spumigena under low (median 315 mu atm), mid (median 353 mu atm), and high (median 548 mu atm) CO2 concentrations. Our results demonstrate an overall stimulating effect of rising pCO(2) on C and N-2 fixation, as well as on cell growth. An increase in pCO(2) during incubation days 0 to 9 resulted in an elevation in growth rate by 84 +/- 38% (low vs. high pCO(2)) and 40 +/- 25% (mid vs. high pCO(2)), as well as in N-2 fixation by 93 +/- 35% and 38 +/- 1%, respectively. C uptake rates showed high standard deviations within treatments and in between sampling days. Nevertheless, C fixation in the high pCO(2) treatment was elevated compared to the other two treatments by 97% (high vs. low) and 44% (high vs. mid) at day 0 and day 3, but this effect diminished afterwards. Additionally, elevation in carbon to nitrogen and nitrogen to phosphorus ratios of the particulate biomass formed (POC : POP and PON : POP) was observed at high pCO(2). Our findings suggest that rising pCO(2) stimulates the growth of heterocystous diazotrophic cyanobacteria, in a similar way as reported for the non-heterocystous diazotroph Trichodesmium. Implications for biogeochemical cycling and food web dynamics, as well as ecological and socio-economical aspects in the Baltic Sea are discussed.
We study resonances for the generator of a diffusion with small noise in R(d) : L = -∈∆ + ∇F * ∇, when the potential F grows slowly at infinity (typically as a square root of the norm). The case when F grows fast is well known, and under suitable conditions one can show that there exists a family of exponentially small eigenvalues, related to the wells of F. We show that, for an F with a slow growth, the spectrum is R+, but we can find a family of resonances whose real parts behave as the eigenvalues of the "quick growth" case, and whose imaginary parts are small.
We argue that the theories of Volokitin and Persson (2014 New J. Phys. 16 118001), Dedkov and Kyasov (2008 J. Phys.: Condens. Matter 20 354006), and Pieplow and Henkel (2013 New J. Phys. 15 023027) agree on the electromagnetic force on a small, polarizable particle that is moving parallel to a planar, macroscopic body, as far as the contribution of evanescent waves is concerned. The apparent differences are discussed in detail and explained by choices of units and integral transformations. We point out in particular the role of the Lorentz contraction in the procedure used by Volokitin and Persson, where a macroscopic body is 'diluted' to obtain the force on a small particle. Differences that appear in the contribution of propagating photons are briefly mentioned.
The main goal of our target article was to provide concrete recommendations for improving the replicability of research findings. Most of the comments focus on this point. In addition, a few comments were concerned with the distinction between replicability and generalizability and the role of theory in replication. We address all comments within the conceptual structure of the target article and hope to convince readers that replication in psychological science amounts to much more than hitting the lottery twice.
We introduce renormalized integrals which generalize conventional measure theoretic integrals. One approximates the integration domain by measure spaces and defines the integral as the limit of integrals over the approximating spaces. This concept is implicitly present in many mathematical contexts such as Cauchy's principal value, the determinant of operators on a Hilbert space and the Fourier transform of an L^p function. We use renormalized integrals to define a path integral on manifolds by approximation via geodesic polygons. The main part of the paper is dedicated to the proof of a path integral formula for the heat kernel of any self-adjoint generalized Laplace operator acting on sections of a vector bundle over a compact Riemannian manifold.
Removing spatial responses reveals spatial concepts even in a culture with mixed reading habits
(2014)
Reflections of Lusáni Cissé
(2016)
Recollecting Bones
(2016)
In the same “guarded, roundabout and reticent way” which Lindsay Barrett invokes for Australian conversations about imperial injustice, Germans, too, must begin to more systematically explore, in Paul Gilroy’s words, “the connections and the differences between anti-semitism and anti-black and other racisms and asses[s] the issues that arise when it can no longer be denied that they interacted over a long time in what might be seen as Fascism’s intellectual, ethical and scientific pre-history” (Gilroy 1996: 26). In the meantime, we need to care for the dead. We need to return them, first, from the status of scientific objects to the status of ancestral human beings, and then progressively, and proactively, as close as possible to the care of those communities from whom they were stolen.
In this work we are concerned with the characterization of certain classes of stochastic processes via duality formulae. First, we introduce a new formulation of a characterization of processes with independent increments, which is based on an integration by parts formula satisfied by infinitely divisible random vectors. Then we focus on the study of the reciprocal classes of Markov processes. These classes contain all stochastic processes having the same bridges, and thus similar dynamics, as a reference Markov process. We start with a resume of some existing results concerning the reciprocal classes of Brownian diffusions as solutions of duality formulae. As a new contribution, we show that the duality formula satisfied by elements of the reciprocal class of a Brownian diffusion has a physical interpretation as a stochastic Newton equation of motion. In the context of pure jump processes we derive the following new results. We will analyze the reciprocal classes of Markov counting processes and characterize them as a group of stochastic processes satisfying a duality formula. This result is applied to time-reversal of counting processes. We are able to extend some of these results to pure jump processes with different jump-sizes, in particular we are able to compare the reciprocal classes of Markov pure jump processes through a functional equation between the jump-intensities.
In this work we study reciprocal classes of Markov walks on graphs. Given a continuous time reference Markov chain on a graph, its reciprocal class is the set of all probability measures which can be represented as a mixture of the bridges of the reference walks. We characterize reciprocal classes with two different approaches. With the first approach we found it as the set of solutions to duality formulae on path space, where the differential operators have the interpretation of the addition of infinitesimal random loops to the paths of the canonical process. With the second approach we look at short time asymptotics of bridges. Both approaches allow an explicit computation of reciprocal characteristics, which are divided into two families, the loop characteristics and the arc characteristics. They are those specific functionals of the generator of the reference chain which determine its reciprocal class. We look at the specific examples such as Cayley graphs, the hypercube and planar graphs. Finally we establish the first concentration of measure results for the bridges of a continuous time Markov chain based on the reciprocal characteristics.
Processes having the same bridges as a given reference Markov process constitute its reciprocal class. In this paper we study the reciprocal class of a continuous time random walk with values in a countable Abelian group, we compute explicitly its reciprocal characteristics and we present an integral characterization of it. Our main tool is a new iterated version of the celebrated Mecke's formula from the point process theory, which allows us to study, as transformation on the path space, the addition of random loops. Thanks to the lattice structure of the set of loops, we even obtain a sharp characterization. At the end, we discuss several examples to illustrate the richness of reciprocal classes. We observe how their structure depends on the algebraic properties of the underlying group.
Processes having the same bridges as a given reference Markov process constitute its reciprocal class. In this paper we study the reciprocal class of compound Poisson processes whose jumps belong to a finite set A in R^d. We propose a characterization of the reciprocal class as the unique set of probability measures on which a family of time and space transformations induces the same density, expressed in terms of the reciprocal invariants. The geometry of A plays a crucial role in the design of the transformations, and we use tools from discrete geometry to obtain an optimal characterization. We deduce explicit conditions for two Markov jump processes to belong to the same class. Finally, we provide a natural interpretation of the invariants as short-time asymptotics for the probability that the reference process makes a cycle around its current state.
In the modern industrialized countries every year several hundred thousands of people die due to the sudden cardiac death. The individual risk for this sudden cardiac death cannot be defined precisely by common available, non-invasive diagnostic tools like Holter-monitoring, highly amplified ECG and traditional linear analysis of heart rate variability (HRV). Therefore, we apply some rather unconventional methods of nonlinear dynamics to analyse the HRV. Especially, some complexity measures that are basing on symbolic dynamics as well as a new measure, the renormalized entropy, detect some abnormalities in the HRV of several patients who have been classified in the low risk group by traditional methods. A combination of these complexity measures with the parameters in the frequency domain seems to be a promising way to get a more precise definition of the individual risk. These findings have to be validated by a representative number of patients.
Prosody and information status in typological perspective - Introduction to the Special Issue
(2015)
Preface to the special issue "Triggered and induced seismicity: probabilities and discrimination"
(2013)
Preface
(2011)
Postcolonial Piracy
(2016)
Media piracy is a contested term in the academic as much as the public debate. It is used by the corporate industries as a synonym for the theft of protected media content with disastrous economic consequences. It is celebrated by technophile elites as an expression of freedom that ensures creativity as much as free market competition. Marxist critics and activists promote flapiracy as a subversive practice that undermines the capitalist world system and its structural injustices. Artists and entrepreneurs across the globe curse it as a threat to their existence, while many use pirate infrastructures and networks fundamentally for the production and dissemination of their art. For large sections of the population across the global South, piracy is simply the only means of accessing the medial flows of a progressively globalising planet.
Postcolonial Justice
(2016)
Contents: 1 Introduction 2 Experiment 3 Data 4 Symbolic dynamics 4.1 Symbolic dynamics as a tool for data analysis 4.2 2-symbols coding 4.3 3-symbols coding 5 Measures of complexity 5.1 Word statistics 5.2 Shannon entropy 6 Testing for stationarity 6.1 Stationarity 6.2 Time series of cycle durations 6.3 Chi-square test 7 Control parameters in the production of rhythms 8 Analysis of relative phases 9 Discussion 10 Outlook
We establish in this paper the existence of weak solutions of infinite-dimensional shift invariant stochastic differential equations driven by a Brownian term. The drift function is very general, in the sense that it is supposed to be neither small or continuous, nor Markov. On the initial law we only assume that it admits a finite specific entropy. Our result strongly improves the previous ones obtained for free dynamics with a small perturbative drift. The originality of our method leads in the use of the specific entropy as a tightness tool and on a description of such stochastic differential equation as solution of a variational problem on the path space.
Does working in a gender-atypical occupation reduce individuals’ likelihood of finding a different-sex romantic partner, and do such occupational partnership penalties contribute to occupational gender segregation? To answer this question, we theorized partnership penalties for working in gender-atypical occupations by drawing on insights from evolutionary psychology, social constructivism, and rational choice theory and exploited the stability of occupational pathways in Germany. In Study 1, we analyzed observational data from a national probability sample (N= 1,634,944) to assess whether individuals in gender-atypical occupations were less likely to be partnered than individuals who worked in gender typical occupations. To assess whether the observed partnership gaps found in Study 1 were causally related to the gender typicality of men’s and women’s occupations, we conducted a field experiment on a dating app (N = 6,778). Because the findings from Study 2 suggested that young women and men indeed experienced penalties for working in a gender-atypical occupation (at least when they were not highly attractive), we employed a choice-experimental design in Study 3 (N = 1,250) to assess whether women and men were aware of occupational partnership penalties and showed that anticipating occupational partnership penalties may keep young and highly educated women from working in gender-atypical occupations. Our main conclusion therefore is that that observed penalties and their anticipation seem to be driven by unconscious rather than conscious processes.
This paper deals with the Mie scattering kernels for multi-spectral data. The kernels may be represented in form of power series. Furthermore, the singular-value spectrum and the degree of ill-posedness in dependence on the refractive index of the particles are numerically approximated. A special hybrid regularization technique allows us to determine via inversion the particle distributions of different types.
Parafoveal preview benefit (PB) is an implicit measure of lexical activation in reading. PB has been demonstrated for orthographic and phonological but not for semantically related information in English. In contrast, semantic PB is obtained in German and Chinese. We propose that these language differences reveal differential resource demands and timing of phonological and semantic decoding in different orthographic systems.