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Static Spherically Symmetric Einstein-aether modelsMay 02 2019May 07 2019We investigate the field equations in the Einstein-aether theory for static spherically symmetric spacetimes and a perfect fluid source and subsequently with the addition of a scalar field (with an exponential self-interaction potential). We introduce ... More

Phase Space of Anisotropic $R^n$ CosmologiesMar 08 2014We construct general anisotropic cosmological scenarios governed by an $f(R)=R^n$ gravitational sector. Focusing then on some specific geometries, and modelling the matter content as a perfect fluid, we perform a phase-space analysis. We analyze the possibility ... More

Qualitative analysis and characterization of two cosmologies including scalar fieldsDec 17 2014The problem of dark energy can be roughly stated as the proposition and validation of a cosmological model that can explain the phenomenon of the accelerated expansion of the Universe. This problem is an open discussion topic in modern physics. One of ... More

On the Past Asymptotic Dynamics of Non-minimally Coupled Dark EnergyDec 04 2008We apply dynamical systems techniques to investigate cosmological models inspired in scalar-tensor theories written in the Einstein frame. We prove that if the potential and the coupling function are sufficiently smooth functions, the scalar field almost ... More

Non-minimally coupled scalar field cosmology with torsionApr 15 2017Apr 17 2018In this work we present a generalized Brans-Dicke lagrangian including a non-minimally coupled Gauss-Bonnet term without imposing the vanishing torsion condition. In the resulting field equations, the torsion is closely related to the dynamics of the ... More

The past and future dynamics of quintom dark energy modelsAug 16 2018Sep 21 2018We study the phase space of the quintom cosmologies for a class of exponential potentials. We combine normal forms expansions and the center manifold theory in order to describe the dynamics near equilibrium sets. Furthermore, we construct the unstable ... More

Asymptotic behavior of Cardassian cosmologies with exponential potentialsMar 22 2005In this paper we analyze the asymptotic behavior of Cardassian cosmological models filled with a perfect fluid and a scalar field with an exponential potential. Cardassian cosmologies arise from modifications of the Friedmann equation, and among the different ... More

Extended phase-space analysis of the Hořava-Lifshitz cosmologyFeb 23 2019We examine the phase space of Ho\v{r}ava-Lifshitz cosmology for a wide range of self-interacting potentials for the scalar field under the detailed - balance condition and without imposing it, by means of the powerful method of $f$-devisers. A compactification ... More

Cosmological solutions in Hořava-Lifshitz gravityMar 26 2019We perform a detailed study on the integrability of the Ho\v{r}% ava-Lifshitz scalar field cosmology in a Friedmann--Lema\^{\i}% tre--Robertson--Walker background spacetime. The approach we follow to determine the integrability is that of the Singularity ... More

Extended phase-space analysis of the Hořava-Lifshitz cosmologyFeb 23 2019Mar 09 2019We examine the phase space of Ho\v{r}ava-Lifshitz cosmology for a wide range of self-interacting potentials for the scalar field under the detailed-balance condition and without imposing it, by means of the powerful method of $f$-devisers. A compactification ... More

Dynamics of the anisotropic Kantowsky-Sachs geometries in $R^n$ gravityJul 22 2010Mar 01 2011We construct general anisotropic cosmological scenarios governed by an $f(R)$ gravitational sector. Focusing then on Kantowski-Sachs geometries in the case of $R^n$-gravity, and modelling the matter content as a perfect fluid, we perform a detailed phase-space ... More

Cosmological dynamical systemsDec 18 2014In this book are studied, from the perspective of the dynamical systems, several Universe models. In chapter 1 we give a bird's eye view on cosmology and cosmological problems. Chapter 2 is devoted to a brief review on some results and useful tools from ... More

Phantom dark energy with varying-mass dark matter particles: acceleration and cosmic coincidence problemApr 09 2009We investigate several varying-mass dark-matter particle models in the framework of phantom cosmology. We examine whether there exist late-time cosmological solutions, corresponding to an accelerating universe and possessing dark energy and dark matter ... More

Cosmology in time asymmetric extensions of general relativityApr 28 2015Nov 09 2015We investigate the cosmological behavior in a universe governed by time asymmetric extensions of general relativity, which is a novel modified gravity based on the addition of new, time-asymmetric, terms on the Hamiltonian framework, in a way that the ... More

Some remarks about non-minimally coupled scalar field modelsMay 10 2014Oct 12 2014Several results related to flat Friedmann-Lema\^{\i}tre-Robertson-Walker models in the conformal (Einstein) frame of scalar-tensor gravity theories are extended. Scalar fields with arbitrary (positive) potentials and arbitrary coupling functions are considered. ... More

Qualitative analysis of Kantowski-Sachs metric in a generic class of $f(R)$ modelsAug 27 2013May 26 2014In this paper we investigate, from the dynamical systems perspective, the evolution of a Kantowski-Sachs metric in a generic class of $f(R)$ models. We present conditions (i. e., differentiability conditions, existence of minima, monotony intervals, etc.) ... More

Dynamical analysis of generalized Galileon cosmologyNov 13 2012Mar 21 2013We perform a detailed dynamical analysis of generalized Galileon cosmology, incorporating also the requirements of ghost and instabilities absence. We find that there are not any new stable late-time solutions apart from those of standard quintessence. ... More

Dynamical behavior in mimetic F(R) gravityDec 31 2014Apr 21 2015We investigate the cosmological behavior of mimetic F(R) gravity. This scenario is the F(R) extension of usual mimetic gravity classes, which are based on re-parametrizations of the metric using new, but not propagating, degrees of freedom, that can lead ... More

Phase-space analysis of Horava-Lifshitz cosmologySep 19 2009We perform a detailed phase-space analysis of Horava-Lifshitz cosmology, with and without the detailed-balance condition. Under detailed-balance we find that the universe can reach a bouncing-oscillatory state at late times, in which dark-energy, behaving ... More

Dynamical behavior in $f(T,T_G)$ cosmologyApr 28 2014Aug 16 2014The $f(T,T_G)$ class of gravitational modification, based on the quadratic torsion scalar $T$, as well as on the new quartic torsion scalar $T_G$ which is the teleparallel equivalent of the Gauss-Bonnet term, is a novel theory, different from both $f(T)$ ... More

Dynamics of Quintessence Models of Dark Energy with Exponential Coupling to the Dark MatterFeb 08 2007We explore quintessence models of dark energy which exhibit non-minimal coupling between the dark matter and the dark energy components of the cosmic fluid. The kind of coupling chosen is inspired in scalar-tensor theories of gravity. We impose a suitable ... More

Cosmological behavior in extended nonlinear massive gravityJan 30 2013Jun 04 2013We perform a detailed dynamical analysis of various cosmological scenarios in extended (varying-mass) nonlinear massive gravity. Due to the enhanced freedom in choosing the involved free functions, this cosmological paradigm allows for a huge variety ... More

Intermediate accelerated solutions as generic late-time attractors in a modified Jordan-Brans-Dicke theoryMay 31 2015Feb 13 2016We investigate a Jordan-Brans-Dicke (JBD) scalar field, $\Phi$, with power-law potential in the presence of a second scalar field, $\phi$, with an exponential potential, in both the Jordan and the Einstein frames. We present the relation of our model ... More

Quintom phase-space: beyond the exponential potentialAug 01 2012Feb 25 2013We investigate the phase-space structure of the quintom dark energy paradigm in the framework of spatially flat and homogeneous universe. Considering arbitrary decoupled potentials, we find certain general conditions under which the phantom dominated ... More

Static Spherically Symmetric Einstein-aether models: Integrability and the Modified Tolman-Oppenheimer-Volkoff approachJun 13 2019We study the evolution of the dynamics and the existence of analytic solutions for the field equations in the Einstein-aether theory for a static spherically symmetric spacetime. In particular, we investigate if the gravitational field equations in the ... More

Quintessence models of Dark Energy with non-minimal couplingFeb 19 2005We explore quintessence models of dark energy which exhibit non-minimal coupling between the dark matter and the dark energy components of the cosmic fluid. The kind of coupling chosen is inspired in scalar-tensor theories of gravity. We impose a suitable ... More

Kantowski-Sachs Einstein-aether perfect fluid modelsJun 28 2016Oct 10 2016We investigate Kantowski-Sachs models in Einstein-aether theory with a perfect fluid source using the singularity analysis to prove the integrability of the field equations and dynamical system tools to study the evolution. We find an inflationary source ... More

Stability of a modified Jordan-Brans-Dicke theory in the dilatonic frameDec 10 2018We investigate the Jordan-Brans-Dicke action in the cosmological scenario of FLRW spacetime with zero spatially curvature and with an extra scalar field minimally coupled to gravity as matter source. The field equations are studied with two ways. The ... More

Equilibrium sets in quintom cosmologies: the past asymptotic dynamicsDec 03 2008Dec 02 2009In the previous paper \cite{Lazkoz:2006pa} was investigated the phase space of quintom cosmologies for a class of exponential potentials. This study suggests that the past asymptotic dynamics of such a model can be approximated by the dynamics near a ... More

Phase-space of flat Friedmann-Robertson-Walker models with both a scalar field coupled to matter and radiationSep 03 2010We investigate the phase-space of a flat FRW universe including both a scalar field, $\phi,$ coupled to matter, and radiation. The model is inspired in scalar-tensor theories of gravity, and thus, related with $F(R)$ theories through conformal transformation. ... More

Exact Solutions in Multi-Scalar Field CosmologyNov 25 2018In multi-scalar field cosmologies new dynamical degrees of freedom are introduced which can explain the observational phenomena. Unlike the usual scalar field theory where a single scalar field is considered, the multi-scalar field cosmologies allow more ... More

Phase-Space analysis of Teleparallel Dark EnergyFeb 15 2012Jul 06 2012We perform a detailed dynamical analysis of the teleparallel dark energy scenario, which is based on the teleparallel equivalent of General Relativity, in which one adds a canonical scalar field, allowing also for a nonminimal coupling with gravity. We ... More

Asymptotic behavior of a scalar field with an arbitrary potential trapped on a Randall-Sundrum's braneworld: the effect of a negative dark radiation term on a Bianchi I braneJan 11 2013Oct 30 2013In this work we present a phase space analysis of a quintessence field and a perfect fluid trapped in a Randall-Sundrum's Braneworld of type 2. We consider a homogeneous but anisotropic Bianchi I brane geometry. Moreover, we consider the effect of the ... More

Phase space analysis of quintessence fields trapped in a Randall-Sundrum braneworld: a refined studyOct 08 2011Aug 09 2012In this paper we investigate, from the dynamical systems perspective, the evolution of an scalar field with arbitrary potential trapped in a Randall-Sundrum's Braneworld of type II. We consider an homogeneous and isotropic Friedmann-Robertson-Walker (FRW) ... More

Dynamical Analysis of an Integrable Cubic Galileon Cosmological ModelMar 17 2017May 31 2017Recently a cubic Galileon cosmological model was derived by the assumption that the field equations are invariant under the action of point transformations. The cubic Galileon model admits a second conservation law which means that the field equations ... More

Dynamical system analysis at background and perturbation levels: Quintessence in severe disadvantage comparing to $Λ$CDMApr 02 2019Aug 01 2019We perform for the first time a dynamical system analysis of both the background and perturbation equations, of $\Lambda$CDM cosmology and quintessence scenario with an exponential potential. In the former case the perturbations do not change the stability ... More

Phase space analysis of quintessence fields trapped in a Randall-Sundrum Braneworld: anisotropic Bianchi I brane with a Positive Dark Radiation termJan 26 2012Oct 26 2012In this paper we investigate, from the dynamical systems perspective, the evolution of an scalar field with arbitrary potential trapped in a Randall-Sundrum's Braneworld of type 2. We consider an homogeneous but anisotropic Bianchi I (BI) brane filled ... More

Noether symmetries and stability of ideal gas solution in Galileon CosmologyFeb 06 2017Mar 03 2017A class of generalized Galileon cosmological models, which can be described by a point-like Lagrangian, is considered in order to utilize Noether's Theorem to determine conservation laws for the field equations. In the Friedmann-Lema\^itre-Robertson-Walker ... More

Spherically symmetric Einstein-aether perfect fluid modelsAug 02 2015Dec 05 2015We investigate spherically symmetric cosmological models in Einstein-aether theory with a tilted (non-comoving) perfect fluid source. We use a 1+3 frame formalism and adopt the comoving aether gauge to derive the evolution equations, which form a well-posed ... More

Dynamical system analysis at background and perturbation levels: Quintessence in severe disadvantage comparing to $Λ$CDMApr 02 2019We perform for the first time a dynamical system analysis of both the background and perturbation equations, of $\Lambda$CDM and quintessence scenarios. In the former case the perturbations do not change the stability of the late-time attractor of the ... More

Dynamical analysis of anisotropic scalar-field cosmologies for a wide range of potentialsAug 07 2013Mar 17 2014We perform a detailed dynamical analysis of anisotropic scalar-field cosmologies, and in particular of the most significant Kantowski-Sachs, Locally Rotationally Symmetric (LRS) Bianchi I and LRS Bianchi III cases. We follow the new and powerful method ... More

Falsifying cosmological models based on a non-linear electrodynamicsSep 28 2017May 28 2018Recently, the nonlinear electrodynamics (NED) has been gaining attention to generate primordial magnetic fields in the Universe and also to resolve singularity problems. Moreover, recent works have shown the crucial role of the NED on the inflation. This ... More

Higher Order Lagrangians inspired by the Pais-Uhlenbeck Oscillator and their cosmological applicationsAug 25 2014May 31 2015We study higher derivative terms associated with scalar field cosmology. We consider a coupling between the scalar field and the geometry inspired by the Pais-Uhlenbeck oscillator, given by $\alpha\partial_{\mu}\partial^{\mu}\phi\partial_{\nu}\partial^{\nu}\phi.$ ... More

Dynamical systems analysis of the cubic galileon beyond the exponential potential and the cosmological analogue of the vDVZ discontinuityJan 07 2018Jun 16 2018In this paper we generalize the dynamical systems analysis of the cubic galileon model previously investigated in \cite{rtgui} by including self-interaction potentials beyond the exponential one. It will be shown that, consistently with the results of ... More

Falsifying Field-based Dark Energy ModelsDec 02 2009We survey the application of specific tools to distinguish amongst the wide variety of dark energy models that are nowadays under investigation. The first class of tools is more mathematical in character: the application of the theory of dynamical systems ... More

Thawing models in the presence of a generalized Chaplygin gasMar 22 2013Oct 30 2013In this paper we consider a cosmological model whose main components are a scalar field and a generalized Chaplygin gas. We obtain an exact solution for a flat arbitrary potential. This solution have the right dust limit when the Chaplygin parameter $A\rightarrow ... More

Global structure of static spherically symmetric solutions surrounded by quintessenceFeb 06 2017May 26 2017We investigate all static spherically symmetric solutions in the context of general relativity surrounded by a minimally-coupled quintessence field, using dynamical system analysis. Applying the 1+1+2 formalism and introducing suitable normalized variables ... More

Coevolution. Extending Prigogine TheoremSep 19 2006Apr 30 2008The formal consideration of the concept of interaction in thermodynamic analysis makes it possible to deduce, in the broadest terms, new results related to the coevolution of interacting systems, irrespective of their distance from thermodynamic equilibrium. ... More

Hilbert's machine and w-orderAug 14 2006Nov 23 2009Hilbert's machine is a supertask machine inspired by Hilbert's Hotel whose functioning leads to a contradictory result involving w-ordering.

Heavy and Light Monopoles in Magnetic Reversion in Artificial Spin IceAug 30 2012This work makes a theoretical study of the dynamics of emergent elemental excitations in artificial spin ice systems with hexagonal geometry during the magnetic reversion of the system. The magnetic and physical parameters of the nanoislands that form ... More

The effect of the size of the system, aspect ratio and impurities concentration on the dynamic of emergent magnetic monopoles in artificial spin ice systemsAug 16 2012In this work we study the dynamical properties of a finite array of nanomagnets in artificial kagome spin ice at room temperature. The dynamic response of the array of nanomagnets is studied by implementing a "frustrated celular aut\'omata" (FCA), based ... More

On Bifurcated supertasks and related questionsJan 24 2010Jan 25 2012Bifurcated supertasks entail the actual infinite division of time (accelerated system of reference) as well as the existence of half-curves of infinite length (supertask system of reference). This paper analyzes both issues from a critique perspective. ... More

New special functions solving nonlinear autonomous dynamical systemsOct 14 2009A general solution is found for a large class of time continuous autonomous nonlinear dynamical systems, the so-called quasi-polynomial systems. This solution is expressed in terms of a new type of special functions defined via their Taylor series. The ... More

Nonlinear supratransmission as a fundamental instabilityOct 08 2003The nonlinear supratransmission is the property of a nonlinear system possessing a natural forbidden band gap to transmit energy of a signal with a frequency in the gap by means of generation of nonlinear modes (gap solitons). This process is shown to ... More

Time-of-arrival formalism for the relativistic particleAug 09 1996Nov 26 1996A suitable operator for the time-of-arrival at a detector is defined for the free relativistic particle in 3+1 dimensions. For each detector position, there exists a subspace of detected states in the Hilbert space of solutions to the Klein Gordon equation. ... More

Nonlinear integrable systems related to arbitrary space-time dependence of the spectral transformJan 14 1994We propose a general algebraic analytic scheme for the spectral transform of solutions of nonlinear evolution equations. This allows us to give the general integrable evolution corresponding to an arbitrary time and space dependence of the spectral transform ... More

Tensor, Symmetric, Exterior, and Other Powers of Persistence ModulesMar 28 2015We reformulate the persistent (co)homology of simplicial filtrations, viewed from a more algebraic setting, namely as the (co)homology of a chain complex of graded modules over polynomial ring $K[t]$. We also define persistent (co)homology of groups, ... More

Excitonic order at strong-coupling: pseudo-spins, doping, and ferromagnetismFeb 17 2000A tight binding model is introduced to describe the strong interaction limit of excitonic ordering. At stoichiometry, the model reduces in the strong coupling limit to a pseudo-spin model with approximate U(4) symmetry. Excitonic order appears in the ... More

Topics in Quantum Geometry of Riemann Surfaces: Two-Dimensional Quantum GravitySep 15 1994Sep 19 1994Lectures given at International School of Physics ``Enrico Fermi'', Varenna, Villa Monastero, June 28-July 7 1994

Desiderata for Vector-Space Word RepresentationsAug 06 2016A plethora of vector-space representations for words is currently available, which is growing. These consist of fixed-length vectors containing real values, which represent a word. The result is a representation upon which the power of many conventional ... More

Classical Limit of Demagnetization in a Field GradientAug 29 2002We calculate the rate of decrease of the expectation value of the transverse component of spin for spin-1/2 particles in a magnetic field with a spatial gradient, to determine the conditions under which a previous classical description is valid. A density ... More

Nonlinear Evolution of Ion Kinetic Instabilities in the Solar WindMar 27 2019In-situ observations of the solar wind (SW) plasma from 0.29 to 1AU show that the protons and alpha particles are often non-Maxwellian, with evidence of kinetic instabilities, temperature anisotropies, differential ion streaming, and associated magnetic ... More

An Approximation for Square Roots known in India prior to Alexander's ConquestOct 20 2010This paper was published in French under the title \textit{Sur une m\'ethode d'approximation des racines carr\'ees dans l'Inde ant\'erieurement \`a la conqu\^ete d'Alexandre}, in the Bulletin de la S. M. F., volume 7 (1879), p. 98-102. It argues that ... More

Nested-set inconsistencyApr 26 2010Jan 25 2012This paper examines a denumerable version of the nested-set theorem and derives from it a contradiction involving the formal consistency of the actual infinity assumed by the Axiom of Infinity.

Living beings as informed systems: towards a physical theory of informationSep 19 2006I propose here a new concept of information based on two relevant aspects of its expression. The first related to the undeniable fact that the expression of information modifies the physical state of its receiver. The second to the arbitrariness of such ... More

Time of arrival in Classical and Quantum MechanicsAug 04 2000The time of arrival at an arbitrary position in configuration space can be given as a function of the phase space variables for the Liouville integrable systems of classical mechanics, but only for them. We review the Jacobi-Lie transformation that explicitly ... More

Nonlinear states and nonlinear tunneling in a potential wellFeb 26 2004Mar 04 2004A nonlinear Schroedinger model in a square well and managed nonlinearity is shown to possess nonlinear states as continuous extensions of the linear levels. The solutions are remarkably stable up to a threshold amplitude where a soliton is emitted and ... More

Orthogonality Catastrophes in Carbon NanotubesJun 02 1999Carbon nanotubes provide a remarkably versatile system in which to explore the effects of Coulomb interactions in one dimension. The most dramatic effects of strong electron-electron repulsion are *orthogonality catastrophes*. These orthogonality catastrophes ... More

Energy density of variational statesAug 26 2014We show, in several important and general cases, that a low variational energy density of a trial state is possible even when the trial state represents a different phase from the ground state. Specifically, we ask whether the ground state energy density ... More

Is quantum mechanics based on an invariance principle?Oct 27 2006Apr 27 2007Non-relativistic quantum mechanics for a free particle is shown to emerge from classical mechanics through an invariance principle under transformations that preserve the Heisenberg position-momentum inequality. These transformations are induced by isotropic ... More

Liouville Theory: Ward Identities for Generating Functional and Modular GeometryMar 02 1994We continue the study of quantum Liouville theory through Polyakov's functional integral \cite{Pol1,Pol2}, started in \cite{T1}. We derive the perturbation expansion for Schwinger's generating functional for connected multi-point correlation functions ... More

On Foundation of the Generalized Nambu MechanicsJan 26 1993We outline the basic principles of canonical formalism for the Nambu mechanics---a generalization of Hamiltonian mechanics proposed by Yoichiro Nambu in 1973. It is based on the notion of Nambu bracket which generalizes the Poisson bracket to the multiple ... More

Cantor versus CantorJan 17 2010Jan 25 2012This paper examines the possibilities of extending Cantor's two arguments on the uncountable nature of the set of real numbers to one of its proper denumerable subsets: the set of rational numbers. The paper proves that, unless certain restrictive conditions ... More

Beyond ChaosApr 18 2008The first part of this paper defines recursive interactions by means of logistic functions and derives a general result on the way interacting systems evolve in attractors. It also defines the notion of coevolution trajectory and presents a new family ... More

Recursion and w-orderApr 18 2008Apr 29 2008This paper has been withdrawn by the author due to an error.

Correcting a minor error in Cantor's calculation of the power of the continuumSep 21 2006Cantor's algebraic calculation of the power of the continuum contains an easily repairable error related to Cantor own way of defining the addition of cardinal numbers. The appropriate correction is suggested.

Recursion and the Axiom of InfinitySep 07 2006Jan 27 2012This paper examines the completion of an w-ordered sequence of recursive definitions which on the one hand defines an increasing sequence of nested set and on the other redefines successively a numeric variable as the cardinal of the successively defined ... More

A general asymptotic decay lemma for elliptic problemsJun 03 2008We prove a general asymptotic decay lemma which is applicable in various contexts. As an example, the general theorem is shown to give lower growth estimates for entire and exterior solutions of the minimal surface equation.

Solution of the Dirichlet boundary value problem for the Sine-Gordon equationApr 17 2002The sine-Gordon equation in light cone coordinates is solved when Dirichlet conditions on the L-shape boundaries of the strip [0,T]X[0,infinity) are prescribed in a class of functions that vanish (mod 2 pi) for large x at initial time. The method is based ... More

Liouville Theory: Quantum Geometry of Riemann SurfacesAug 26 1993Inspired by Polyakov's original formulation of quantum Liouville theory through functional integral, we analyze perturbation expansion around a classical solution. We show the validity of conformal Ward identities for puncture operators and prove that ... More

Absorption of a Particle by a Rotating Black Hole: The Potential BarrierJun 09 2016For a test particle approaching a rapidly rotating black hole we find a range of values of the particle's energy and angular momentum, on the order of 1\% or more of the corresponding values of the hole, such that three conditions are satisfied. 1) The ... More

The Aleph-zero or zero dichotomyApr 18 2008Nov 23 2009This paper proves the existence of a dichotomy which being formally derived from the topological successiveness of w-order leads to the same absurdity of Zeno's Dichotomy II. It also derives a contradictory result from the first Zeno's Dichotomy.

SuperswappingApr 18 2008Jan 27 2012Supertask theory is used here to prove a contradictory result which involves the consistency of w-order and the Axiom of Infinity.

Transfinite partitions of Jordan curvesAug 21 2006The w-asymmetry induced by transfinite partitions makes it impossible for Jordan curves to have an infinite length.

Chain complex reduction using steepness matchingsMar 02 2019Computing the homology of a chain complex with algebraic Morse theory is like doing Gaussian elimination, but only \emph{on certain columns/rows} and \emph{with several pivots} (in all the matrices at once). This significantly reduces fill-in and coefficient ... More

Solution of SRS on the finite intervalOct 16 1995Feb 22 1996The equations of transient stimulated Raman scattering on the finite interval are solved by the spectral transform method on the semi-line. As the problem has a free end, the pump and Stokes output at finite distance can be constructed as the solution ... More

``X-Ray Edge'' Singularities in Nanotubes and Quantum Wires with Multiple SubbandsFeb 11 1999Band theory predicts an inverse square root van Hove singularity in the tunneling density of states at the minimum energy of an unoccupied subband in a one-dimensional quantum wire. With interactions, an orthogonality catastrophe analogous to the x-ray ... More

Spatially Ordered Fractional Quantum Hall StatesFeb 02 1995Fractional quantum Hall liquids can accomodate various degrees of spatial ordering. The most likely scenarios are a Hall hexatic, Hall smectic, and Hall crystal, in which respectively orientational, one--dimensional translational, and two--dimensional ... More

Localization of Elastic Layers by Correlated DisorderOct 01 1993The equilibrium behavior of a system of elastic layers under tension in the presence of correlated disorder is studied using functional renormalization group techniques. The model exhibits many of the features of the Bose glass phase of type II superconductors ... More

Extending Cantor ParadoxSep 12 2008Jan 24 2012The inconsistencies involved in the foundation of set theory were invariably caused by infinity and self-reference; and only with the opportune axiomatic restrictions could them be obviated. Throughout history, both concepts have proved to be an exhaustible ... More

A disturbing supertaskApr 18 2008Jan 27 2012This paper examines the consistency of w-order by means of a supertask that functions as a supertrap for the assumed existence of w-ordered collections, which are simultaneously complete (as is required by the Actual infinity) and uncompletable (because ... More

Simple Natural Language Processing Tools for DanishJun 27 2019This technical note describes a set of baseline tools for automatic processing of Danish text. The tools are machine-learning based, using natural language processing models trained over previously annotated documents. They are maintained at ITU Copenhagen ... More

A position and a time for the photonSep 04 2003This paper gives a constructive answer to the question whether photon states can contain or not, and to what extent, the readings of rulers and clocks. The paper first shows explicitly that, along with the momentum representation, there is room in the ... More

Quintom cosmologies admitting either tracking or phantom attractorsFeb 27 2006In this paper we investigate the evolution of a class of cosmologies fuelled by quintom dark energy and dark matter. Quintom dark energy is a hybrid of quintessence and phantom which involves the participation of two reals scalar fields playing the roles ... More

Indonesian's presidential social media campaignsSep 30 2014Social media has been used for political campaigns of presidential candidates in a number of democratic countries, including Indonesia.The candidates for president and vice president have been following the latest trends in the virtual world by using ... More

Perancangan basisdata sistem informasi penggajianFeb 02 2013The purpose of this research is to design database scheme of information system at XYZ University. By using database design methods (conceptual scheme, logical scheme, & physical scheme) the writer designs payroll information system. The physical scheme ... More

PDF articles metadata harvesterJan 28 2013Scientific journals are very important in recording the finding from researchers around the world. The recent media to disseminate scientific journals is PDF. On scheme to find the scientific journals over the internet is via metadata. Metadata stores ... More

Non-dispersive optics using storage of lightMar 17 2010We demonstrate the non-dispersive deflection of an optical beam in a Stern-Gerlach magnetic field. An optical pulse is initially stored as a spin-wave coherence in thermal rubidium vapour. An inhomogeneous magnetic field imprints a phase gradient onto ... More

Phenomenology of retained refractoriness: On semi-memristive discrete mediaNov 15 2011We study two-dimensional cellular automata, each cell takes three states: resting, excited and refractory. A resting cell excites if number of excited neighbours lies in a certain interval (excitation interval). An excited cell become refractory independently ... More

Continuous 3d Freezing Transition in Layered SuperconductorsAug 26 1995We use Ginzburg-Landau theory to study the $H_{c2}$ transition in layered superconductors with field parallel to the layers, finding a continuous 3d freezing transition to a triangular vortex super-solid in the three-dimensional XY universality class. ... More