Results for "Claudius Hubig"

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Gaussian time dependent variational principle for the Bose-Hubbard modelJul 10 2019Jul 18 2019We systematically extend Bogoliubov theory beyond the mean field approximation of the Bose-Hubbard model in the superfluid phase. Our approach is based on the time dependent variational principle applied to the family of all Gaussian states (i.e. Gaussian ... More
Time-evolution methods for matrix-product statesJan 17 2019Feb 18 2019Matrix-product states have become the de facto standard for the representation of one-dimensional quantum many body states. During the last few years, numerous new methods have been introduced to evaluate the time evolution of a matrix-product state. ... More
Gaussian TDVP for the Bose-Hubbard modelJul 10 2019We systematically extend Bogoliubov theory beyond the mean field approximation of the Bose- Hubbard model in the superfluid phase. Our approach is based on the time dependent variational principle applied to the family of all Gaussian states (i.e., Gaussian ... More
Time-dependent study of disordered models with infinite projected entangled pair statesDec 10 2018Feb 14 2019Infinite projected entangled pair states (iPEPS), the tensor network ansatz for two-dimensional systems in the thermodynamic limit, already provide excellent results on ground-state quantities using either imaginary-time evolution or variational optimisation. ... More
Universal long-time behavior of stochastically driven interacting quantum systemsSep 27 2016Nov 01 2016One of the most important concepts in non-equilibrium physics is relaxation. In the vicinity of a classical critical point, the relaxation time can diverge and result in a universal power-law for the relaxation dynamics; the emerging classification of ... More
Universal long-time behavior of stochastically driven interacting quantum systemsSep 27 2016One of the most important concepts in non-equilibrium physics is relaxation. In the vicinity of a classical critical point, the relaxation time can diverge and result in a universal power-law for the relaxation dynamics; the emerging classification of ... More
Doped Kondo chain, a heavy Luttinger liquidOct 13 2017May 16 2018The one dimensional $SU(2)$ Kondo Lattice model is studied by Density Matrix Renormalization Group away from half-filling. We find signatures of a Heavy Tomonaga-Luttinger Liquid (HTLL) phase, which describes one dimensional Heavy Fermions. We compute ... More
A Strictly Single-Site DMRG Algorithm with Subspace ExpansionJan 22 2015Apr 12 2015We introduce a strictly single-site DMRG algorithm based on the subspace expansion of the Alternating Minimal Energy (AMEn) method. The proposed new MPS basis enrichment method is sufficient to avoid local minima during the optimisation, similarly to ... More
Time-evolution methods for matrix-product statesJan 17 2019Matrix-product states have become the de facto standard for the representation of one-dimensional quantum many body states. During the last few years, numerous new methods have been introduced to evaluate the time evolution of a matrix-product state. ... More
Higgs Effective Field Theories - Systematics and ApplicationsOct 26 2016We discuss effective field theories (EFTs) for the Higgs particle, which is not necessarily the Higgs of the Standard Model. We distinguish two different consistent expansions: EFTs that describe decoupling new-physics effects and EFTs that describe non-decoupling ... More
Entrenched time delays versus accelerating opinion dynamics: are advanced democracies inherently unstable?Sep 18 2017Oct 02 2017Modern societies face the challenge that the time scale of opinion formation is continuously accelerating in contrast to the time scale of political decision making. With the latter remaining of the order of the election cycle we examine here the case ... More
Why planetary and exoplanetary protection differ: The case of long duration Genesis missions to habitable but sterile M-dwarf oxygen planetsJan 08 2019Time is arguably the key limiting factor for interstellar exploration. At high speeds, flyby missions to nearby stars by laser propelled wafersats taking 50-100 years would be feasible. Directed energy launch systems could accelerate on the other side ... More
Control of the finite size corrections in exact diagonalization studiesNov 23 1995We study the possibility of controlling the finite size corrections in exact diagonalization studies quantitatively. We consider the one- and two dimensional Hubbard model. We show that the finite-size corrections can be be reduced systematically by a ... More
Secant Varieties of Segre--Veronese VarietiesNov 26 2010Nov 11 2011We prove that the ideal of the variety of secant lines to a Segre--Veronese variety is generated in degree three by minors of flattenings. In the special case of a Segre variety this was conjectured by Garcia, Stillman and Sturmfels, inspired by work ... More
Generating functionals for guided self-organizationJul 30 2013Time evolution equations for dynamical systems can often be derived from generating functionals. Examples are Newton's equations of motion in classical dynamics which can be generated within the Lagrange or the Hamiltonian formalism. We propose that generating ... More
Self-Sustained Thought Processes in a Dense Associative NetworkAug 22 2005Mar 02 2007Several guiding principles for thought processes are proposed and a neural-network-type model implementing these principles is presented and studied. We suggest to consider thinking within an associative network built-up of overlapping memory states. ... More
Quantum phases and topological properties of interacting fermions in one-dimensional superlatticesMar 14 2019The realization of artificial gauge fields in ultracold atomic gases has opened up a path towards experimental studies of topological insulators and, as an ultimate goal, topological quantum matter in many-body systems. As an alternative to the direct ... More
Dynamical topological quantum phase transitions in nonintegrable modelsApr 01 2019We consider sudden quenches across quantum phase transitions in the $S=1$ XXZ model starting from the Haldane phase. We demonstrate that dynamical phase transitions may occur during these quenches that are identified by nonanalyticities in the rate function ... More
Thin interface limit for phase-field models of solidification with local mobility correctionMay 08 2019A new approach is developed to derive an analytical form for mobility corrections in phase-field models for pure material solidification. Similar to the thin interface limit approach (Karma and Rappel, 1996) it seeks to remove systematic errors in the ... More
Progressive Blue SurfelsJun 30 2013In this paper we describe a new technique to generate and use surfels for rendering of highly complex, polygonal 3D scenes in real time. The basic idea is to approximate complex parts of the scene by rendering a set of points (surfels). The points are ... More
Products of Young symmetrizers and ideals in the generic tensor algebraJan 31 2013May 08 2013We describe a formula for computing the product of the Young symmetrizer of a Young tableau with the Young symmetrizer of a subtableau, generalizing the classical quasi-idempotence of Young symmetrizers. We derive some consequences to the structure of ... More
Regularity and cohomology of determinantal thickeningsNov 01 2016We consider the ring S=C[x_ij] of polynomial functions on the vector space C^(m x n) of complex m x n matrices. We let GL= GL_m x GL_n and consider its action via row and column operations on C^(m x n) (and the induced action on S). For every GL-invariant ... More
Pushing the complexity barrier: diminishing returns in the sciencesSep 10 2012Sep 14 2012Are the sciences not advancing at an ever increasing speed? We contrast this popular perspective with the view that science funding may actually see diminishing returns, at least regarding established fields. In order to stimulate a larger discussion, ... More
Neural networks with transient state dynamicsMay 01 2007We investigate dynamical systems characterized by a time series of distinct semi-stable activity patterns, as they are observed in cortical neural activity patterns. We propose and discuss a general mechanism allowing for an adiabatic continuation between ... More
Universal scaling relation for magnetic sails: momentum braking in the limit of dilute interstellar mediaJul 10 2017May 09 2018The recent progress in laser propulsion research has advanced substantially the prospects to realize interstellar spaceflight within a few decades. Here we examine passive deceleration via momentum braking from ionized interstellar media. The very large ... More
Equation of motion approach to the Hubbard model in infinite dimensionsMar 08 1994We consider the Hubbard model on the infinite-dimensional Bethe lattice and construct a systematic series of self-consistent approximations to the one-particle Green's function, $G^{(n)}(\omega),\ n=2,3,\dots\ $ . The first $n-1$ equations of motion are ... More
Peculiar modules for 4-ended tanglesDec 13 2017Apr 09 2019With a 4-ended tangle $T$, we associate a Heegaard Floer invariant $\operatorname{CFT^\partial}(T)$, the peculiar module of $T$. Based on Zarev's bordered sutured Heegaard Floer theory, we prove a glueing formula for this invariant which recovers link ... More
Affine Toric Equivalence Relations are EffectiveMay 29 2009Aug 25 2009Any map of schemes $X\to Y$ defines an equivalence relation $R=X\times_Y X\to X\times X$, the relation of "being in the same fiber". We have shown elsewhere that not every equivalence relation has this form, even if it is assumed to be finite. By contrast, ... More
Characters of equivariant D-modules on Veronese conesDec 28 2014Jul 23 2015For d > 1, we consider the Veronese map of degree d on a complex vector space W , Ver_d : W -> Sym^d W , w -> w^d , and denote its image by Z. We describe the characters of the simple GL(W)-equivariant holonomic D-modules supported on Z. In the case when ... More
Representation stability for syzygies of line bundles on Segre--Veronese varietiesSep 06 2012The rational homology groups of the packing complexes are important in algebraic geometry since they control the syzygies of line bundles on projective embeddings of products of projective spaces (Segre--Veronese varieties). These complexes are a common ... More
Iterative Methods for Systems' Solving - a C# approachMay 28 2009This work wishes to support various mathematical issues concerning the iterative methods with the help of new programming languages. We consider a way to show how problems in math have an answer by using different academic resources and different thoughts. ... More
On a polynomial Alexander invariant for tangles and its categorificationJan 19 2016We generalise the Kauffman state formula for the classical multivariate Alexander polynomial of knots and links to tangles and thereby obtain a finite set of polynomial tangle invariants. In the first part of this paper, we investigate some of their properties; ... More
Emotional control - conditio sine qua non for advanced artificial intelligences?Dec 06 2011Humans dispose of two intertwined information processing pathways, cognitive information processing via neural firing patterns and diffusive volume control via neuromodulation. The cognitive information processing in the brain is traditionally considered ... More
Emotions, diffusive emotional control and the motivational problem for autonomous cognitive systemsJan 20 2009All self-active living beings need to solve the motivational problem: The question what to do at any moment of their live. For humans and non-human animals at least two distinct layers of motivational drives are known, the primary needs for survival and ... More
An empirical study of the per capita yield of science Nobel prizes: Is the US era coming to an end?Apr 11 2018We point out that the Nobel prize production of the USA, the UK, Germany and France has been in numbers that are large enough to allow for a reliable analysis or the long-term historical developments. Nobel prizes are often split, such that up to three ... More
Developing Ecospheres on Transiently Habitable Planets: The Genesis ProjectAug 22 2016Sep 01 2016It is often presumed, that life evolves relatively fast on planets with clement conditions, at least in its basic forms, and that extended periods of habitability are subsequently needed for the evolution of higher life forms. Many planets are however ... More
Cognitive computation with autonomously active neural networks: an emerging fieldJan 20 2009The human brain is autonomously active. To understand the functional role of this self-sustained neural activity, and its interplay with the sensory data input stream, is an important question in cognitive system research and we review here the present ... More
Autonomous Dynamics in Neural networks: The dHAN Concept and Associative Thought ProcessesMar 01 2007The neural activity of the human brain is dominated by self-sustained activities. External sensory stimuli influence this autonomous activity but they do not drive the brain directly. Most standard artificial neural network models are however input driven ... More
3x3 Minors of CatalecticantsNov 06 2010May 08 2013Secant varieties to Veronese embeddings of projective space are classical varieties whose equations are not completely understood. Minors of catalecticant matrices furnish some of their equations, and in some situations even generate their ideals. Geramita ... More
Characters of equivariant D-modules on spaces of matricesJul 23 2015Jan 16 2016We compute the characters of the simple GL-equivariant holonomic D-modules on the vector spaces of general, symmetric and skew-symmetric matrices. We realize some of these D-modules explicitly as subquotients in the pole order filtration associated to ... More
Generic Construction of Efficient Matrix Product OperatorsNov 08 2016Matrix Product Operators (MPOs) are at the heart of the second-generation Density Matrix Renormalisation Group (DMRG) algorithm formulated in Matrix Product State language. We give an introduction to arithmetic with general MPOs and compression of general ... More
On a Heegaard Floer theory for tanglesOct 24 2016The purpose of this thesis is to define a "local" version of Ozsv\'{a}th and Szab\'{o}'s Heegaard Floer homology $\operatorname{\widehat{HFL}}$ for links in the 3-dimensional sphere, i.e. a Heegaard Floer homology $\operatorname{\widehat{HFT}}$ for tangles ... More
Cognition and Emotion: Perspectives of a Closing GapFeb 16 2010The primary tasks of a cognitive system is to survive and to maximize a life-long utility function, like the number of offsprings. A direct computational maximization of life-long utility is however not possible in complex environments, especially in ... More
Expanding advanced civilizations in the universeJan 07 2005The 1950 lunch-table remark by Enrico Fermi `Where is everybody' has started intensive scientific and philosophical discussions about what we call nowadays the `Fermi paradox': If there had been ever a single advanced civilization in the cosmological ... More
Homological invariants of determinantal thickeningsDec 28 2017The study of homological invariants such as Tor, Ext and local cohomology modules constitutes an important direction in commutative algebra. Explicit descriptions of these invariants are notoriously difficult to find and often involve combining an array ... More
Regularity and cohomology of determinantal thickeningsNov 01 2016Aug 12 2017We consider the ring S=C[x_ij] of polynomial functions on the vector space C^(m x n) of complex m x n matrices. We let GL= GL_m x GL_n and consider its action via row and column operations on C^(m x n) (and the induced action on S). For every GL-invariant ... More
Interaction quench and thermalization in a one-dimensional topological Kondo insulatorOct 23 2018Feb 26 2019We study the nonequilibrium dynamics of a one-dimensional topological Kondo insulator, modelled by a $p$-wave Anderson lattice model, following a quantum quench of the on-site interaction strength. Our goal is to examine how the quench influences the ... More
Density-matrix embedding theory study of the one-dimensional Hubbard-Holstein modelOct 31 2018We present a density-matrix embedding theory (DMET) study of the one-dimensional Hubbard-Holstein model, which is paradigmatic for the interplay of electron-electron and electron-phonon interactions. Analyzing the single-particle excitation gap, we find ... More
Chern-Simons and RG Flows: Contact with DualitiesMay 09 2014May 27 2014Contact terms in two point functions of global symmetry currents have recently been proposed as a check of Seiberg-like duality in three dimensional supersymmetric field theories. In this paper we compute the contact terms for various N=2 dual pairs in ... More
Observing scale-invariance in non-critical dynamical systemsOct 12 2012Recent observation for scale invariant neural avalanches in the brain have been discussed in details in the scientific literature. We point out, that these results do not necessarily imply that the properties of the underlying neural dynamics are also ... More
Quantum Monte Carlo simulation for the conductance of one-dimensional quantum spin systemsSep 16 2003Nov 03 2003Recently, the stochastic series expansion (SSE) has been proposed as a powerful MC-method, which allows simulations at low $T$ for quantum-spin systems. We show that the SSE allows to compute the magnetic conductance for various one-dimensional spin systems ... More
Vertex routing modelsJun 26 2009A class of models describing the flow of information within networks via routing processes is proposed and investigated, concentrating on the effects of memory traces on the global properties. The long-term flow of information is governed by cyclic attractors, ... More
Ramsey interferometry of Rydberg ensembles inside microwave cavitiesOct 20 2017Jun 15 2018We study ensembles of Rydberg atoms in a confined electromagnetic environment such as provided by a microwave cavity. The competition between standard free space Ising type and cavity-mediated interactions leads to the emergence of different regimes where ... More
Generating functionals for autonomous latching dynamics in attractor relict networksDec 20 2012Jan 15 2013Well characterized sequences of dynamical states play an important role for motor control and associative neural computation in the brain. Autonomous dynamics involving sequences of transiently stable states have been termed associative latching in the ... More
Self-organized stochastic tipping in slow-fast dynamical systemsJul 12 2012Polyhomeostatic adaption occurs when evolving systems try to achieve a target distribution function for certain dynamical parameters, a generalization of the notion of homeostasis. Here we consider a single rate encoding leaky integrator neuron model ... More
Dynamics of the Peierls-active phonon modes in CuGeO_3Apr 08 1998We reconsider the Cross and Fischer approach to spin-Peierls transitions. We show that a soft phonon occurs only if Omega_0<2.2 T_SP. For CuGeO_3 this condition is not fulfilled and the calculated temperature dependence of the Peierls-active phonon modes ... More
Introduction to uniformity in commutative algebraAug 29 2014These notes are based on three lectures given by the first author as part of an introductory workshop at MSRI for the program in Commutative Algebra, 2012-13. The notes follow the talks, but there are extra comments and explanations, as well as a new ... More
Self-organized chaos through polyhomeostatic optimizationJan 05 2010May 28 2010The goal of polyhomeostatic control is to achieve a certain target distribution of behaviors, in contrast to polyhomeostatic regulation which aims at stabilizing a steady-state dynamical state. We consider polyhomeostasis for individual and networks of ... More
Complex activity patterns generated by short-term synaptic plasticityMar 14 2018Short-term synaptic plasticity (STSP) affects the efficiency of synaptic transmission for persistent presynaptic activities. We consider attractor neural networks, for which the attractors are given, in the absence of STSP, by cell assemblies of excitatory ... More
Restoration of Images with Wavefront AberrationsApr 02 2017This contribution deals with image restoration in optical systems with coherent illumination, which is an important topic in astronomy, coherent microscopy and radar imaging. Such optical systems suffer from wavefront distortions, which are caused by ... More
Spin-charge separation at small lengthscales in the 2D t-J modelApr 15 1994We consider projected wavefunctions for the 2D $t-J$ model. For various wavefunctions, including correlated Fermi-liquid and Luttinger-type wavefunctions we present the static charge-charge and spin-spin structure factors. Comparison with recent results ... More
An objective function for self-limiting neural plasticity rulesMay 15 2015Self-organization provides a framework for the study of systems in which complex patterns emerge from simple rules, without the guidance of external agents or fine tuning of parameters. Within this framework, one can formulate a guiding principle for ... More
Local cohomology with support in ideals of symmetric minors and PfaffiansSep 14 2015We compute the local cohomology modules H_Y^(X,O_X) in the case when X is the complex vector space of n x n symmetric, respectively skew-symmetric matrices, and Y is the closure of the GL-orbit consisting of matrices of any fixed rank, for the natural ... More
Dynamical topological quantum phase transitions in nonintegrable modelsApr 01 2019Jul 01 2019We consider sudden quenches across quantum phase transitions in the $S=1$ XXZ model starting from the Haldane phase. We demonstrate that dynamical phase transitions may occur during these quenches that are identified by nonanalyticities in the rate function ... More
Generating functionals for computational intelligence: the Fisher information as an objective function for self-limiting Hebbian learning rulesOct 02 2014Generating functionals may guide the evolution of a dynamical system and constitute a possible route for handling the complexity of neural networks as relevant for computational intelligence. We propose and explore a new objective function, which allows ... More
Spin dynamics of dimerized Heisenberg chainsDec 02 1996We study numerically the dimerized Heisenberg model with frustration appropriate for the quasi-1D spin-Peierls compound CuGeO$_3$. We present evidence for a bound state in the dynamical structure factor for any finite dimerization $\delta$ and estimate ... More
Tangential varieties of Segre-Veronese varietiesNov 26 2011Feb 01 2013We determine the minimal generators of the ideal of the tangential variety of a Segre-Veronese variety, as well as the decomposition into irreducible GL-representations of its homogeneous coordinate ring. In the special case of a Segre variety, our results ... More
The syzygies of some thickenings of determinantal varietiesNov 01 2014Jan 16 2016The vector space of m x n complex matrices (m >= n) admits a natural action of the group GL = GL_m x GL_n via row and column operations. For positive integers a,b, we consider the ideal I_{a x b} defined as the smallest GL-equivariant ideal containing ... More
Molecular-field approach to the spin-Peierls transition in CuGeO_3May 12 1997May 26 1997We present a theory for the spin-Peierls transition in CuGeO_3. We map the elementary excitations of the dimerized chain (solitons) on an effective Ising model. Inter-chain coupling (or phonons) then introduce a linear binding potential between a pair ... More
Design of Artificial Intelligence Agents for Games using Deep Reinforcement LearningMay 10 2019In order perform a large variety of tasks and to achieve human-level performance in complex real-world environments, Artificial Intelligence (AI) Agents must be able to learn from their past experiences and gain both knowledge and an accurate representation ... More
A versatile class of prototype dynamical systems for complex bifurcation cascades of limit cyclesApr 13 2015We introduce a versatile class of prototype dynamical systems for the study of complex bifurcation cascades of limit cycles, including bifurcations breaking spontaneously a symmetry of the system, period doubling bifurcations and transitions to chaos ... More
Two-trace model for spike-timing-dependent synaptic plasticityOct 02 2014We present an effective model for timing-dependent synaptic plasticity (STDP) in terms of two interacting traces, corresponding to the fraction of activated NMDA receptors and the Ca2+ concentration in the dendritic spine of the postsynaptic neuron. This ... More
Evolving complex networks with conserved clique distributionsJun 18 2008We propose and study a hierarchical algorithm to generate graphs having a predetermined distribution of cliques, the fully connected subgraphs. The construction mechanism may be either random or incorporate preferential attachment. We evaluate the statistical ... More
Learning in cognitive systems with autonomous dynamicsApr 08 2008The activity patterns of highly developed cognitive systems like the human brain are dominated by autonomous dynamical processes, that is by a self-sustained activity which would be present even in the absence of external sensory stimuli. During normal ... More
Drifting states and synchronization induced chaos in autonomous networks of excitable neuronsSep 21 2016The study of balanced networks of excitatory and inhibitory neurons has led to several open questions. On the one hand it is yet unclear whether the asynchronous state observed in the brain is autonomously generated, or if it results from the interplay ... More
Syzygies of determinantal thickenings and representations of the general linear Lie superalgebraAug 16 2018We let S denote the ring of polynomial functions on the space of m x n matrices, and consider the action of the group GL = GL_m x GL_n via row and column operations on the matrix entries. For a GL-invariant ideal I in S we show that the linear strands ... More
Extended Supersymmetry on Curved SpacesAug 05 2013Aug 16 2013We study N=2 superconformal theories on Euclidean and Lorentzian four-manifolds with a view toward applications to holography and localization. The conditions for supersymmetry are equivalent to a set of differential constraints including a "generalised" ... More
The loss of interest for the euro in RomaniaSep 07 2016We generalize a money demand micro-founded model to explain Romanians' recent loss of interest for the euro. We show that the reason behind this loss of interest is a severe decline in the relative degree of the euro liquidity against that of the Romanian ... More
A journey to 3d: exact relations for adjoint SQCD from dimensional reductionSep 30 2014May 25 2015In this note we elaborate on the reduction of four dimensional Seiberg duality with adjoint matter to three dimensions. We use the exact formulation of the superconformal index and of the partition function as instruments to test this reduction. We translate ... More
Intrinsic adaptation in autonomous recurrent neural networksOct 14 2011A massively recurrent neural network responds on one side to input stimuli and is autonomously active, on the other side, in the absence of sensory inputs. Stimuli and information processing depends crucially on the qualia of the autonomous-state dynamics ... More
Power laws and Self-Organized Criticality in Theory and NatureOct 21 2013Dec 12 2013Power laws and distributions with heavy tails are common features of many experimentally studied complex systems, like the distribution of the sizes of earthquakes and solar flares, or the duration of neuronal avalanches in the brain. Previously, researchers ... More
Local cohomology with support in generic determinantal idealsSep 03 2013For positive integers m >= n >= p, we compute the GL_m x GL_n-equivariant description of the local cohomology modules of the polynomial ring S of functions on the space of m x n matrices, with support in the ideal of p x p minors. Our techniques allow ... More
Low-temperature transport in Heisenberg chainsMay 30 2001Jan 18 2002A technique to determine accurately transport properties of integrable and non-integrable quantum-spin chains at finite temperatures by Quantum Monte-Carlo is presented. The reduction of the Drude weight by interactions in the integrable gapless regime ... More
The Spin-SAF transition in NaV2O5 induced by spin-pseudospin couplingMar 10 2004We present microscopic estimates for the spin-spin and spin-speudospin interactions of the quarter-filled ladder compound NaV2O5, obtained by exactly diagonalizing appropriate clusters of the underlying generalized Hubbard Hamiltonian. We present evidence ... More
On the evaluation of the specific heat and general off-diagonal n-point correlation functions within the loop algorithmFeb 09 2000Feb 11 2000We present an efficient way to compute diagonal and off-diagonal n-point correlation functions for quantum spin-systems within the loop algorithm. We show that the general rules for the evaluation of these correlation functions take an especially simple ... More
Conductivity of quantum-spin chains: A Quantum Monte Carlo approachApr 15 2002We discuss zero-frequency transport properties of various spin-1/2 chains. We show, that a careful analysis of Quantum Monte-Carlo (QMC) data on the imaginary axis allows to distinguish between intrinsic ballistic and diffusive transport. We determine ... More
Anomalous thermal conductivity of frustrated Heisenberg spin-chains and laddersJan 17 2002Sep 09 2002We study the thermal transport properties of several quantum spin chains and ladders. We find indications for a diverging thermal conductivity at finite temperatures for the models examined. The temperature at which the non-diverging prefactor \kappa^{(th)}(T) ... More
Semi-Invariant Submanifolds in Metric Geometry of AffinorsSep 03 2011We introduce a generalization of structured manifolds as the most general Riemannian metric g associated to an affinor (tensor field of (1,1)-type) F and initiate a study of their semi-invariant submanifolds. These submanifolds are generalization of CR-submanifolds ... More
Distinct values of bilinear forms on algebraic curvesMar 16 2014Feb 21 2015Let $B$ be a bilinear form on pairs of points in the complex plane, of the form $B(p,q) = p^TMq$, for an invertible $2\times2$ complex matrix $M$. We prove that any finite set $S$ contained in an irreducible algebraic curve $C$ of degree $d$ in $\mathbb{C}^2$ ... More
A Self-Organized Neural ComparatorOct 23 2012Oct 25 2012Learning algorithms need generally the possibility to compare several streams of information. Neural learning architectures hence need a unit, a comparator, able to compare several inputs encoding either internal or external information, like for instance ... More
The interaction between trade and FDI: the CEE countries experienceSep 08 2016Inside the EU, the commercial integration of the CEE countries has gained remarkable momentum before the crisis appearance, but it has slightly slowed down afterwards. Consequently, the interest in identifying the factors supporting the commercial integration ... More
Quasi-satellite dynamics in formation flightJan 01 2016The quasi-satellite (QS) phenomenon makes two celestial bodies to fly near each other (Mikkola et al. 2006) and that effect can be used also to make artificial satellites move in tandem. We consider formation flight of two or three satellites in low eccentricity ... More
Iterated local cohomology groups and Lyubeznik numbers for determinantal ringsMay 22 2018We give an explicit recipe for determining iterated local cohomology groups with support in ideals of minors of a generic matrix in characteristic zero, expressing them as direct sums of indecomposable D-modules. For non-square matrices these indecomposables ... More
Near equipartitions of colored point setsFeb 06 2016Oct 12 2016Suppose that $nk$ points in general position in the plane are colored red and blue, with at least $n$ points of each color. We show that then there exist $n$ pairwise disjoint convex sets, each of them containing $k$ of the points, and each of them containing ... More
Attractor metadynamics in a recurrent neural network: adiabatic vs. symmetry protected flowNov 01 2016In dynamical systems with distinct time scales the time evolution in phase space may be influenced strongly by slow manifolds. Orbits then typically follow the slow manifold, which hence act as a transient attractor, performing in addition rapid transitions ... More
Partially predictable chaosMay 18 2016Sep 14 2016For a chaotic system pairs of initially close-by trajectories become eventually fully uncorrelated on the attracting set. This process of decorrelation is split into an initial decrease characterized by the maximal Lyapunov exponent and a subsequent diffusive ... More
Strong coupling and long-range collective interactions in optomechanical arraysFeb 28 2012Oct 16 2012We investigate the collective optomechanics of an ensemble of scatterers inside a Fabry-Perot resonator and identify an optimized configuration where the ensemble is transmissive, in contrast with the usual reflective optomechanics approach. In this configuration, ... More
On the number of ordinary conicsNov 11 2015May 21 2016We prove a lower bound on the number of ordinary conics determined by a finite point set in $\mathbb{R}^2$. An ordinary conic for a subset $S$ of $\mathbb{R}^2$ is a conic that is determined by five points of $S$, and contains no other points of $S$. ... More
Link between chips and cutting moments evolutionJan 21 2012The better understanding of the material cutting process has been shown with the benefit of the forces and moments measurement since some years ago. In paper, simultaneous six mechanical components and chip orientation measurements were realized during ... More
A Generalization of Certain Remarkable Points of the Triangle GeometryAug 06 2010In this article we prove a theorem that will generalize the concurrence theorems that are leading to the Franke's point, Kariya's point, and to other remarkable points from the triangle geometry.