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Lyapunov-like functions involving Lie bracketsAug 09 2016For a given closed target we embed the dissipative relation that defines a control Lyapunov function in a more general differential inequality involving Hamiltonians built from iterated Lie brackets. The solutions of the resulting extended relation, here ... More

Asymptotic controllability and optimal controlOct 16 2012Dec 11 2012We consider a control problem where the state must reach asymptotically a target while paying an integral payoff with a non-negative Lagrangian. The dynamics is just continuous, and no assumptions are made on the zero level set of the Lagrangian. Through ... More

Necessary conditions involving Lie brackets for impulsive optimal control problems; the commutative caseOct 16 2012In this article we study control problems with systems that are governed by ordinary differential equations whose vector fields depend linearly in the time derivatives of some components of the control. The remaining components are considered as classical ... More

$\mathcal{L}^1$ limit solutions for control systemsJan 01 2014Feb 11 2015For a control Cauchy problem $$\dot x= {f}(t,x,u,v) +\sum_{\alpha=1}^m g_\alpha(x) \dot u_\alpha,\quad x(a)=\bar x, $$ on an interval $[a,b]$, we propose a notion of limit solution $x,$ verifying the following properties: i) $x$ is defined for $\mathcal{L}^1$ ... More

A note on systems with ordinary and impulsive controlsDec 30 2013Feb 11 2015We investigate an everywhere defined notion of solution for control systems whose dynamics depend nonlinearly on the control $u$ and state $x,$ and are affine in the time derivative $\dot u.$ For this reason, the input $u,$ which is allowed to be Lebesgue ... More

On optimal control problems with impulsive commutative dynamicsNov 26 2013We consider control systems governed by nonlinear O.D.E.'s that are affine in the time-derivative du/dt of the control u. The latter is allowed to be an integrable, possibly of unbounded variation function, which gives the system an impulsive character. ... More

GAC, savings, and unbounded inputsMar 11 2015Jun 08 2016Let a control system and a target be given on an open subset of an Euclidean space. The existence of a Control Lyapunov Function - namely a positive definite, semiconcave, solution of the Hamilton-Jacobi inequality corresponding to the control vector ... More

On the Control of Non Holonomic Systems by Active ConstraintsAug 21 2012The paper is concerned with mechanical systems which are controlled by implementing a number of time-dependent, frictionless holonomic constraints. The main novelty is due to the presence of additional non-holonomic constraints. We develop a general framework ... More

Necessary conditions involving Lie brackets for impulsive optimal control problemsMar 14 2019We obtain higher order necessary conditions for a minimum of a Mayer optimal control problem connected with a nonlinear, control-affine system, where the controls range on an m-dimensional Euclidean space. Since the allowed velocities are unbounded and ... More

A Higher-order Maximum Principle for Impulsive Optimal Control ProblemsMar 12 2019We consider a nonlinear control system, affine with respect to an unbounded control $u$ taking values in a closed cone of $\mathbb{R}^m$, and with drift depending on a second, ordinary control $a$, ranging on a bounded set. We provide first and higher ... More

The quest for extragalactic magnetic fieldsOct 31 2016We review the observational and theoretical constraints on extragalactic magnetic fields across cosmic environment. In the next decade, the combination of sophisticated numerical simulations and various observational probes might succeed in constraining ... More

Lorentzian approach to noncommutative geometryAug 02 2011This thesis concerns the research on a Lorentzian generalization of Alain Connes' noncommutative geometry. In the first chapter, we present an introduction to noncommutative geometry within the context of unification theories. The second chapter is dedicated ... More

Towards a noncommutative version of GravitationMar 29 2010Alain Connes' noncommutative theory led to an interesting model including both Standard Model of particle physics and Euclidean Gravity. Nevertheless, an hyperbolic version of the gravitational part would be necessary to make physical predictions, but ... More

The Classification of the Epimorphisms from the Artin-Tits groups of type $A(\widetilde{A}_{n})$ to $W(\widetilde{A}_{n})$Mar 18 2010Nov 29 2010We present a complete classification for the epimorphisms from the affine Artin-Tits groups $A(\widetilde{A}_{n})$ to the corresponding Coxeter groups $W(\widetilde{A}_{n})$, for $n\geq 1$.

Delicious ice Creams in Plain Awful. Why does salt thaw ice?Apr 22 2016Plain Awful is an imaginary valley on the Andes populated by a highly-imitative, cubical people for which the most criminal offence is to exhibit round objects. The duck family (Scrooge, Donald and nephews) are teaming against Scrooge's worst enemy, Flintheart ... More

b decays: a factory for hidden charm multiquark statesJan 11 2018We assume that the two hidden charm pentaquark discovered at $LHCb$ are built by the three light quarks and the $c \bar{c}$ pair, both colour octets. in relative P-wave for the $\frac{5}{2}^+$ state and by the eigenvectors of the chromomagnetic interaction ... More

Symmetries, Symmetry Breaking, Gauge SymmetriesFeb 23 2015Jul 02 2015The concepts of symmetry, symmetry breaking and gauge symmetries are discussed, their operational meaning being displayed by the observables {\em and} the (physical) states. For infinitely extended systems the states fall into physically disjoint {\em ... More

Metaheuristic Approaches to Realistic Portfolio OptimizationJan 04 2005We investigate the application of two heuristic methods, genetic algorithms and tabu/scatter search, to the optimisation of realistic portfolios. The model is based on the classical mean-variance approach, but enhanced with floor and ceiling constraints, ... More

Comment to "Comment on 'Compositional and Microchemical Evidence of Piezonuclear Fission Reactions in Rock Specimens Subjected to Compression Tests' [Strain 47 (Suppl. 2), 282 (2011)]" by G. Amato et alJun 13 2012Feb 23 2016It is shown that the evidence asserted in the Comment [arXiv:1205.6418] on the chemical composition data published by Carpinteri et al. [Strain 47 (Suppl. 2), 282 (2011)]-that the data "cannot be the result of independent measurements as claimed by the ... More

Towards a General Software Engineering Methodology for the Internet of ThingsJan 21 2016As research in the Internet of Thing area progresses, and a multitude of proposals exist to solve a variety of problems, the need for a general principled software engineering approach for the systematic development of IoT systems and applications arises. ... More

Intermittently Flowing Rivers of Quantized Magnetic FluxMar 09 1997Recent experiments and realistic flux-gradient-driven computer simulations provide evidence of plastic flow of flux lines in a superconductor. The striking videos of the onset of vortex motion vividly illustrate the existence of flowing "rivers" of quantized ... More

Belief revision in quantum decision theory: gambler's and hot hand fallaciesJan 29 2008In the present article we introduce a quantum mechanism which is able to describe the creation of correlations in the evaluation of random independent events: such correlations, known as positive and negative recency, correspond respectively to the hot ... More

Risk, ambiguity and quantum decision theoryNov 06 2007In the present article we use the quantum formalism to describe the effects of risk and ambiguity in decision theory. The main idea is that the probabilities in the classic theory of expected utility are estimated probabilities, and thus do not follow ... More

Quantum amplitude amplification algorithm: an explanation of availability biasOct 06 2008In this article, I show that a recent family of quantum algorithms, based on the quantum amplitude amplification algorithm, can be used to describe a cognitive heuristic called availability bias. The amplitude amplification algorithm is used to define ... More

The conjunction fallacy and interference effectsAug 29 2007In the present article we consider the conjunction fallacy, a well known cognitive heuristic experimentally tested in cognitive science, which occurs for intuitive judgments in situations of bounded rationality. We show that the quantum formalism can ... More

Thermodynamics, entropy and waterwheelsSep 15 2016Oct 30 2016In this paper the analogy between a thermal engine and a waterwheel is developed in details, showing that the analogous of the flow of water in an hydraulic engine is the flow of entropy in a thermal one. This analogy mat serve to analyse in details the ... More

Bipartite Field Theories: from D-Brane Probes to Scattering AmplitudesJul 03 2012Dec 20 2012We introduce and initiate the investigation of a general class of 4d, N=1 quiver gauge theories whose Lagrangian is defined by a bipartite graph on a Riemann surface, with or without boundaries. We refer to such class of theories as Bipartite Field Theories ... More

$\Deltag/g$ results from the Open Charm production at COMPASSAug 31 2012One of the main goals of the COMPASS experiment at CERN is the determination of the gluon contribution to the nucleon spin. To achieve this goal COMPASS uses a naturally polarised muon beam with an energy of 160 GeV and a fixed polarised target. Two types ... More

Conjugacy problem for subgroups with applications to Artin groups and braid type groupsNov 15 2004Let $G$ be a group endowed with a solution to the conjugacy problem and with an algorithm which computes the centralizer in $G$ of any element of $G$. Let $H$ be a subgroup of $G$. We give some conditions on $H$, under which we provide a solution to the ... More

Primordial brusque bounce in Born-Infeld determinantal gravityNov 10 2015Jul 06 2016We study a particular exact solution to the Born-Infeld determinantal gravity consisting of a cosmological model which undergoes a brusque bounce. The latter consists of an event characterized by a non-null (but finite) value of the squared Hubble rate ... More

Nonsingular Promises from Born-Infeld GravityJun 18 2013Jul 16 2013Born-Infeld determinantal gravity formulated in Weitzenbock spacetime is discussed in the context of Friedmann-Robertson-Walker (FRW) cosmologies. It is shown how the standard model big bang singularity is absent in certain spatially flat FRW spacetimes, ... More

Truth-value semantics and functional extensions for classical logic of partial terms based on equalityDec 29 2011Dec 01 2012We develop a bottom-up approach to truth-value semantics for classical logic of partial terms based on equality and apply it to prove the conservativity of the addition of partial description and partial selection functions, independently of any strictness ... More

Physical models from noncommutative causalityNov 14 2017We introduced few years ago a new notion of causality for noncommutative spacetimes directly related to the Dirac operator and the concept of Lorentzian spectral triple. In this paper, we review in a non-technical way the noncommutative causal structure ... More

Survey of Gravity in Non-Commutative GeometryApr 28 2009We present a survey of the application of Cones' Non-Commutative Geometry to gravitation. Bases of the theory and Euclidian gravity models are reviewed. Then we discuss the problem of a Lorentzian generalization of the theory and review existing attempts ... More

WDVV EquationsOct 27 2015The paper aims to point out a novel geometric characterisation of the WDVV equations of 2D topological field theory.

The New SI and the CODATA recommended values of the fundamental constants 2014 (arXiv:1507.07956), after the CCU 2016 draft of the 9th SI Brochure and its 22th meetingDec 09 2015Sep 21 2016This note aims at pointing out some standing features of the present and future CODATA method in the light of the recent CODATA table of the 2014 recommended values for the fundamental constants published on paper arXiv:1507.07956, and of the future 2018 ... More

Thermodynamics, entropy and waterwheelsSep 15 2016In textbooks, it is often repeated that Carnot arrived to the formulation of the second law of thermodynamics without knowing the first, using the caloric theory. In fact, in his book, R\'eflexions sur la puissance motrice du feu, he often repeats that ... More

The Unix KISS: A Case StudyJan 04 2007Jul 05 2013In this paper we show that the initial philosophy used in designing and developing UNIX in early times has been forgotten due to "fast practices". We question the leitmotif that microkernels, though being by design adherent to the KISS principle, have ... More

From Newton to Cellular AutomataDec 10 2009I outline a possible logical path from the formulation of physics of classical mechanics to "abstract" systems like cellular automata. The goal of this article is that of illustrating why physicists often study extremely simplified models, instead of ... More

Liquid money or hard cash? Drowning into granular materialApr 22 2016In British English, the term "hard cash" refers to the form of payment using coins or bill, rather than cheques or credit or money transfer. In American English, it is often prefixed by the adjective "cold". On the contrary, in Italian the equivalent ... More

Quantum mechanics, Bayes' theorem and the conjunction fallacyMar 23 2007May 17 2007In the present article we consider the conjunction fallacy, a well known cognitive heuristic experimentally tested in cognitive science, which occurs for intuitive judgments in situations of bounded rationality. We show that the quantum formalism can ... More

Dimer Models, Integrable Systems and Quantum Teichmuller SpaceMay 09 2011Jul 05 2011We introduce a correspondence between dimer models (and hence superconformal quivers) and the quantum Teichmuller space of the Riemann surfaces associated to them by mirror symmetry. Via the untwisting map, every brane tiling gives rise to a tiling of ... More

Global $\widetilde{SL(2,R)}$ representations of the Schrödinger equation with time-dependent potentialsApr 18 2011We study the representation theory of the solution space of the one-dimensional Schr\"{o}dinger equation with time-dependent potentials that posses $\mathfrak{sl}_2$-symmetry. We give explicit local intertwining maps to multiplier representations and ... More

The inverse fallacy and quantum formalismAug 22 2007In the present article we consider the inverse fallacy, a well known cognitive heuristic experimentally tested in cognitive science, which occurs for intuitive judgments in situations of bounded rationality. We show that the quantum formalism can be used ... More

Global Eikonal Condition for Lorentzian Distance Function in Noncommutative GeometryMar 29 2010Aug 17 2010Connes' noncommutative Riemannian distance formula is constructed in two steps, the first one being the construction of a path-independent geometrical functional using a global constraint on continuous functions. This paper generalizes this first step ... More

A critical review of the CCU 2016 Draft of the Brochure for the New SI definition using (fundamental) constantsDec 30 2015Feb 24 2016This v.3, in addition to: (a) discussion of the role of constants (called fundamental until 2015) in the proposed New SI formulation of the definition of the International System of Units, namely in the present official documents and in some relevant ... More

On Damage Spreading TransitionsAug 24 1995We study the damage spreading transition in a generic one-dimensional stochastic cellular automata with two inputs (Domany-Kinzel model) Using an original formalism for the description of the microscopic dynamics of the model, we are able to show analitically ... More

Bursting Money Bins, the ice and water structureApr 22 2016That water expands when freezing is a well-known fact, and it is at the basis of an experiment that is often involuntary performed with beer bottles in freezers. But why does the water behave this way? And, more difficult, how can one illustrate this ... More

Haantjes Manifolds and Veselov SystemsOct 27 2015A novel geometric interpretation of the solutions of the WDVV equations formerly found by A.P. Veselov is suggested.

Grover's algorithm and human memoryApr 21 2008In this article we consider an experimental study showing the influence of emotion regulation strategies on human memory performance: part of such experimental results are difficult to explain within a classic cognitive allocation model. We provide a ... More

Quantum mechanics and rational ignoranceFeb 20 2007In the present article we use the quantum formalism to describe the process of choice under rational ignorance. We consider as a basic task a question or an issue where the only answers are 0 and 1. We show that under rational ignorance the opinion state ... More

Wigner-function description of EPR experimentJan 12 2007We provide a detailed description of the EPR paradox (in the Bohm version) for a two qubit-state in the discrete Wigner function formalism. We compare the probability distributions for two qubit relevant to simultaneously-measurable observables (computed ... More

Cluster Transformations from Bipartite Field TheoriesJan 02 2013Oct 17 2013Bipartite field theories (BFTs) are a new class of 4d N=1 quantum field theories defined by bipartite graphs on bordered Riemann surfaces. In this paper we derive, purely in terms of the gauge theory, the cluster transformations of face weights under ... More

Towards a new quantum cognition modelNov 23 2016This article presents a new quantum-like model for cognition explicitly based on knowledge. It is shown that this model, called QKT (quantum knowledge-based theory), is able to coherently describe some experimental results that are problematic for the ... More

On the complexity and the information content of cosmic structuresNov 28 2016The emergence of cosmic structure is commonly considered one of the most complex phenomena in Nature. However, this complexity has never been defined nor measured in a quantitative and objective way. In this work we propose a method to measure the information ... More

Temporal Lorentzian Spectral TriplesOct 24 2012Aug 25 2014We present the notion of temporal Lorentzian spectral triple which is an extension of the notion of pseudo-Riemannian spectral triple with a way to ensure that the signature of the metric is Lorentzian. A temporal Lorentzian spectral triple corresponds ... More

The Lorentzian distance formula in noncommutative geometryOct 30 2017Jan 24 2018For almost twenty years, a search for a Lorentzian version of the well-known Connes' distance formula has been undertaken. Several authors have contributed to this search, providing important milestones, and the time has now come to put those elements ... More

Torelli problem for Calabi-Yau threefolds with GLSM descriptionNov 28 2017Dec 22 2017We construct a gauged linear sigma model with two non-birational K\"alher phases which we prove to be derived equivalent, $\mathbb{L}$-equivalent, deformation equivalent and Hodge equivalent. This provides a new counterexample to the birational Torelli ... More

Feedback Control of Rabi Oscillations in Circuit QEDApr 22 2013We consider the feedback stabilization of Rabi oscillations in a superconducting qubit which is coupled to a microwave readout cavity. The signal is readout by homodyne detection of the in-phase quadrature amplitude of the weak measurement output. By ... More

Question for SU(5) x SU(5) string unificationApr 14 2011Apr 24 2011The heterotic string theory can embeds the crossed SU(5) x SU(5) gauge group. Here we investigate the string unification in this framework and the concerning problems. We show generically that only a very constrained parameter space is allowed for new ... More

Spherically symmetric static spacetimes in vacuum f(T) gravitySep 20 2011Oct 17 2011We show that Schwarzschild geometry remains as a vacuum solution for those four-dimensional f(T) gravitational theories behaving as ultraviolet deformations of general relativity. In the gentler context of three-dimensional gravity, we also find that ... More

The regular cosmic string in Born-Infeld gravityNov 23 2010It is shown that Born-Infeld gravity --a high energy deformation of Einstein gravity-- removes the singularities of a cosmic string. The respective vacuum solution results to be free of conical singularity and closed timelike curves. The space ends at ... More

Non trivial frames for f(T) theories of gravity and beyondMar 04 2011Jul 19 2011Some conceptual issues concerning $f(T)$ theories --a family of modified gravity theories based on absolute parallelism-- are analyzed. Due to the lack of local Lorentz invariance, the autoparallel frames satisfying the field equations are evasive to ... More

Sipping Science in a CaféMay 19 2011We present here the European project SciCaf\'e - networking of science caf\'es in Europe and neighboring countries, and the contributions of the CSDC-Caff\`e Scienza partner in Florence, Itay.

A study of polymer knots using a simple knot invariant written consisting of multiple contour integralsJun 24 2013Jul 03 2013In this work the thermodynamic properties of short polymer knots (up to 120 segments) defined on a simple cubic lattice are studied with the help of the Wang-Landau Monte Carlo algorithm. The sampling process is performed using pivot transformations starting ... More

Qubit-oscillator systems in the ultrastrong-coupling regime and their potential for preparing nonclassical statesDec 24 2009Apr 17 2010We consider a system composed of a two-level system (i.e. a qubit) and a harmonic oscillator in the ultrastrong-coupling regime, where the coupling strength is comparable to the qubit and oscillator energy scales. Special emphasis is placed on the possibility ... More

Free expansion of Bose-Einstein condensates with quantized vorticesJul 07 1999The expansion of Bose-Einstein condensates with quantized vortices is studied by solving numerically the time-dependent Gross-Pitaevskii equation at zero temperature. For a condensate initially trapped in a spherical harmonic potential, we confirm previous ... More

Solution to HJB equations with an elliptic integro-differential operator and gradient constraintMay 17 2016Oct 07 2016The main goal of this paper is to establish existence, regularity and uniqueness results for the solution of a Hamilton-Jacobi-Bellman (HJB) equation, whose operator is an elliptic integro-differential operator. The HJB equation studied in this work arises ... More

A conceptual roadmap for setting up a system of units in the New SI contextMar 15 2016The definition of a system of units is analysed here as a structural problem, for which the physical theory provides the necessary conditions of realization but remains as backgrounder. The structurally more sophisticated option is provided by the so-called ... More

Decoherence of scalar cosmological perturbationsFeb 15 2010In this paper we analyze the possibility of detecting nontrivial quantum phenomena in observations of the temperature anisotropy of the cosmic background radiation (CBR), for example, if the Universe could be found in a coherent superposition of two states ... More

Moduli spaces of $Λ$-modules on abelian varietiesFeb 19 2016We study the moduli space $\mathbf{M}_X(\Lambda, n)$ of semistable $\Lambda$-modules of vanishing Chern classes over an abelian variety $X$, where $\Lambda$ belongs to a certain subclass of $D$-algebras. In particular, for $\Lambda = \mathcal{D}_X$ (resp. ... More

On the n-Dimensional Porous Medium Diffusion Equation and Global Actions of the Symmetry GroupSep 07 2012Feb 12 2013By restricting to a special class of smooth functions, the local action of the symmetry group is globalized. This special class of functions is constructed using parabolic induction.

On a theorem of Artin, IINov 09 2004This paper is a sequel of [A.M. Cohen, L. Paris, {\it On a theorem of Artin}, J. Group Theory {\bf 6} (2003), 421--441]. Let $A$ be an Artin group, let $W$ be its associated Coxeter group, and let $CA$ be its associated coloured Artin group, that is, ... More

Topological bifurcations in a model society of reasonable contrariansAug 19 2013People are often divided into conformists and contrarians, the former tending to align to the majority opinion in their neighborhood and the latter tending to disagree with that majority. In practice, however, the contrarian tendency is rarely followed ... More

Phase Transitions of Cellular AutomataSep 15 2014We explore some aspects of phase transitions in cellular automata. We start recalling the standard formulation of statistical mechanics of discrete systems (Ising model), illustrating the Monte Carlo approach as Markov chains and stochastic processes. ... More

Mirror symmetry for Nahm branesSep 05 2017Apr 17 2018Using the Dirac--Higgs bundle and the morphism given by tensorization, we consider a new class of virtual hyperholomorphic bundles over the moduli space of M of degree 0 semistable Higgs bundles. This construction generalizes the Nahm transform of a stable ... More

Reduced purities as measures of decoherence in many-electron systemsSep 04 2013A hierarchy of measures of decoherence for many-electron systems that is based on the purity and the hierarchy of reduced electronic density matrices is presented. These reduced purities can be used to characterize electronic decoherence in the common ... More

Colored BPS Pyramid Partition Functions, Quivers and Cluster TransformationsDec 06 2011We investigate the connections between flavored quivers, dimer models, and BPS pyramids for generic toric Calabi-Yau threefolds from various perspectives. We introduce a purely field theoretic definition of both finite and infinite pyramids in terms of ... More

Hydrodynamic limit of gradient exclusion processes with conductancesJun 19 2008Fix a strictly increasing right continuous with left limits function $W: \bb R \to \bb R$ and a smooth function $\Phi : [l,r] \to \bb R$, defined on some interval $[l,r]$ of $\bb R$, such that $0<b \le \Phi'\le b^{-1}$. We prove that the evolution, on ... More

A new criterion based on Kullback-Leibler information for space filling designsApr 16 2009Experimental designs are tools which can drastically reduce the number of simulations required by time-consuming computer codes. One strategy for selecting the values of the inputs, whose response is to be observed, is to choose these values so that they ... More

Continuous dependence on the derivative of generalized heat equationsDec 11 2013We consider here a generalized heat equation $\partial_t \rho=\frac{d}{dx}\frac{d}{dW}\rho$, where $W$ is a finite measure on the one dimensional torus, and $\frac{d}{dW}$ is the Radon-Nikodym derivative with respect to $W$. Such equation has appeared ... More

Finite Mechanical Proxies for a Class of Reducible Continuum SystemsJul 22 2011Apr 26 2013We present the exact finite reduction of a class of nonlinearly perturbed wave equations, based on the Amann-Conley-Zehnder paradigm. By solving an inverse eigenvalue problem, we establish an equivalence between the spectral finite description derived ... More

Gauge Invariance and Symmetry Breaking by Topology and Energy GapNov 05 2015For the description of observables and states of a quantum system, it may be convenient to use a canonical Weyl algebra of which only a subalgebra $\mathcal A$, with a non-trivial center $\mathcal Z$, describes observables, the other Weyl operators playing ... More

Higher Cluster Categories and QFT DualitiesNov 03 2017We present a unified mathematical framework that elegantly describes minimally SUSY gauge theories in even dimension, ranging from $6d$ to $0d$, and their dualities. This approach combines recent developments on graded quiver with potentials, higher Ginzburg ... More

Euler-Lagrangian approach to 3D stochastic Euler equationsMar 14 20183D stochastic Euler equations with a special form of multiplicative noise are considered. A Constantin-Iyer type representation in Euler-Lagrangian form is given, based on stochastic characteristics. Local existence and uniqueness of solutions in suitable ... More

$ρ$-white noise solution to 2D stochastic Euler equationsOct 11 2017Nov 09 2017A stochastic version of 2D Euler equations with transport type noise in the vorticity is considered, in the framework of Albeverio--Cruzeiro theory [1] where the equation is considered with random initial conditions related to the so called enstrophy ... More

Additive continuity of the renormalized volume under geometric limitsAug 14 2017We study the infimum of the renormalized volume for convex-cocompact hyperbolic manifolds, as well as describing how a sequence converging to such values behaves. In particular, we show that the renormalized volume is continuous under the appropriate ... More

An algebraic formulation of causality for noncommutative geometryDec 20 2012May 23 2013We propose an algebraic formulation of the notion of causality for spectral triples corresponding to globally hyperbolic manifolds with a well defined noncommutative generalization. The causality is given by a specific cone of Hermitian elements respecting ... More

Squeezed Phonon States: Modulating Quantum Fluctuations of Atomic DisplacementsSep 19 1996Sep 20 1996We study squeezed quantum states of phonons, which allow the possibility of modulating the quantum fluctuations of atomic displacements below the zero-point quantum noise level of coherent phonon states. We calculate the corresponding expectation values ... More

Phonon Squeezed States Generated by Second Order Raman ScatteringDec 05 1997We study squeezed states of phonons, which allow a reduction in the quantum fluctuations of the atomic displacements to below the zero-point quantum noise level of coherent phonon states. We investigate the generation of squeezed phonon states using a ... More

Random perturbations of nonlinear parabolic systemsJul 29 2011Several aspects of regularity theory for parabolic systems are investigated under the effect of random perturbations. The deterministic theory, when strict parabolicity is assumed, presents both classes of systems where all weak solutions are in fact ... More

Noise Prevents Singularities in Linear Transport EquationsMay 24 2012A stochastic linear transport equation with multiplicative noise is considered and the question of no-blow-up is investigated. The drift is assumed only integrable to a certain power. Opposite to the deterministic case where smooth initial conditions ... More

Speciation as Pattern Formation by Competition in a Smooth Fitness LandscapeAug 14 1997We investigate the problem of speciation and coexistence in simple ecosystems when the competition among individuals is included in the Eigen model for quasi-species. By suggesting an analogy between the competition among strains and the diffusion of ... More

Pump and Probe nonlinear processes: new modified sum rules from a simple oscillator modelApr 26 1999The nonlinear oscillator model is useful to basically understand the most important properties of nonlinear optical processes. It has been shown to give the correct asymptotic behaviour and to provide the general feature of harmonic generation to all ... More

Control-free control: manipulating a quantum system using only a limited set of measurementsNov 19 2010Dec 07 2010We present and discuss different protocols for preparing an arbitrary quantum state of a qubit using only a restricted set of measurements, with no unitary operations at all. We show that an arbitrary state can indeed be prepared, provided that the available ... More

Monte Carlo Computation of the Vassiliev knot invariant of degree 2 in the integral representationJan 06 2014Jan 07 2014In mathematics there is a wide class of knot invariants that may be expressed in the form of multiple line integrals computed along the trajectory C describing the spatial conformation of the knot. In this work it is addressed the problem of evaluating ... More

Ring polymers with topological constraintsFeb 02 2014In the first part of this work a summary is provided of some recent experiments and theoretical results which are relevant in the research of systems of polymer rings in nontrivial topological conformations. Next, some advances in modeling the behavior ... More

Hierarchical community structure in complex (social) networksFeb 28 2014Mar 10 2014The investigation of community structure in networks is a task of great importance in many disciplines, namely physics, sociology, biology and computer science where systems are often represented as graphs. One of the challenges is to find local communities ... More

Nanoporous compound materials for optical applications - microlasers and microresonatorsJun 30 2004This book chapter is the first part of a review of nanoporous materials for optical applications. Whereas the second part [J.Sauer, F. Marlow and F.Schueth, pp. 153-172 of the same volume] discusses material properties, this part gives a self-contained ... More

On the Zero-Slope Limit of the Compactified Closed Bosonic StringDec 07 1993In the framework of the compactified closed bosonic string theory with the extra spatial coordinates being circular with radius $R$, we perform both the zero-slope limit and the $R \rightarrow 0$ limit of the tree scattering amplitude of four massless ... More