Results for "Luigi Delle Site"

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Formulation of Liouville's Theorem for Grand Ensemble Molecular SimulationsFeb 05 2016Mar 29 2016Liouville's theorem in a grand ensemble, that is for situations where a system is in equilibrium with a reservoir of energy and particles, is a subject that, to our knowledge, has not been explicitly treated in literature related to molecular simulation. ... More
Shannon Entropy and Many-Electron Correlations: Theoretical Concepts, Numerical Results and Collins ConjectureNov 12 2014In this paper I will discuss the overlap between the concept of Shannon Entropy and the concept of electronic correlation. Quantum Monte Carlo numerical results for the uniform electron gas are also presented; these latter on the one hand enhance the ... More
Simulation of many-electron systems that exchange matter with the environmentFeb 20 2019The computational treatment of many-electron systems capable of exchanging {electrons and nuclei} with the environment represents one of the outermost frontiers in simulation methodology. The exchanging process occurs in a large variety of natural and ... More
Levy-Lieb Principle meets Quantum Monte CarloNov 20 2013We review an approach where the energy functional of Density-Functional Theory (DFT) can be determined without empiricism via a Quantum Monte Carlo (QMC) procedure. The idea consists of a nested iterative loop where the configurational space of the electrons ... More
On the formalization of Asynchronous First Passage AlgorithmsMar 14 2019The formalization of First Passage schemes is revisited and the emerging of a conceptual contradiction is underlined. We then show why, despite such a contradiction, the numerical results are not explicitly affected. Through a different formalization ... More
On Some Open Problems in Many-Electron TheoryJun 17 2014Jun 24 2014Mel Levy and Elliott Lieb are two of the most prominent researchers who have dedicated their efforts to the investigation of fundamental questions in many-electron theory. Their results have not only revolutionized the theoretical approach of the field, ... More
Solvation of positive ions in water: The dominant role of water-water interactionFeb 09 2007Local polarization effects, induced by mono and divalent positive ions in water, influence (and in turn are influenced by) the large scale structural properties of the solvent. Experiments can only distinguish this process of interplay in a generic qualitative ... More
Grand-Canonical Adaptive Resolution Centroid Molecular Dynamics: Implementation and ApplicationFeb 29 2016May 09 2016We have implemented the Centroid Molecular Dynamics scheme (CMD) into the Grand Canonical-like version of the Adaptive Resolution Simulation Molecular Dynamics (GC-AdResS) method. We have tested the implementation on two different systems, liquid parahydrogen ... More
Path Integral Molecular Dynamics within the Grand Canonical-like Adaptive Resolution Technique: Simulation of Liquid WaterApr 29 2015Jun 18 2015Quantum effects due to the spatial delocalization of light atoms are treated in molecular simulation via the path integral technique. Among several methods, Path Integral (PI) Molecular Dynamics (MD) is nowadays a powerful tool to investigate properties ... More
A Macromolecule in a Solvent: Adaptive Resolution Molecular Dynamics SimulationJan 10 2007We report adaptive resolution molecular dynamics simulations of a flexible linear polymer in solution. The solvent, i.e., a liquid of tetrahedral molecules, is represented within a certain radius from the polymer's center of mass with a high level of ... More
The design of Kinetic Functionals for Many-Body Electron Systems : Combining analytical theory with Monte Carlo sampling of electronic configurationsNov 12 2007In a previous work [L.Delle Site, J.Phys.A 40, 2787 (2007)] the derivation of an analytic expression for the kinetic functional of a many-body electron system has been proposed. Though analytical, the formula is still non local (multidimensional) and ... More
Adaptive Molecular Resolution Approach in Hamiltonian Form: An Asymptotic AnalysisOct 04 2016Oct 05 2016Adaptive Molecular Resolution approaches in Molecular Dynamics are becoming relevant tools for the analysis of molecular liquids characterized by the interplay of different physical scales. The essential difference among these methods is in the way the ... More
pH-dependent coarse-grained model of peptidesDec 18 2012Apr 26 2013We propose the first, to our knowledge, coarse-grained modeling strategy for peptides where the effect of changes of the pH can be efficiently described. The idea is based on modeling the effects of the pH value on the main driving interactions. We use ... More
Adaptive Resolution Molecular Dynamics Simulation: Changing the Degrees of Freedom on the FlyOct 10 2005We present a new adaptive resolution technique for efficient particle-based multiscale molecular dynamics (MD) simulations. The presented approach is tailor-made for molecular systems where atomistic resolution is required only in spatially localized ... More
Influence of pH and sequence in peptide aggregation via molecular simulationAug 13 2015We employ a recently developed coarse-grained model for peptides and proteins where the effect of pH is automatically included. We explore the effect of pH in the aggregation process of the amyloidogenic peptide KTVIIE and two related sequences, using ... More
Nanoscale domains in ionic liquids: A statistical mechanics definition for molecular dynamics studiesMar 14 2019One of the many open questions concerning Ionic Liquids (ILs) is the existence of nanoscale supramolecular domains which characterize the bulk. The hypothesis of their existence does not meet a general consensus since their definition seems to be based ... More
Partitioning a macroscopic system into independent subsystemsMar 31 2017Jun 06 2017We discuss the problem of partitioning a macroscopic system into a collection of independent subsystems. The partitioning of a system into replica-like subsystems is nowadays a subject of major interest in several field of theoretical and applied physics, ... More
Adaptive molecular resolution via a continuous change of the phase space dimensionalitySep 01 2006For the study of complex synthetic and biological molecular systems by computer simulations one is still restricted to simple model systems or to by far too small time scales. To overcome this problem multiscale techniques are being developed for many ... More
pH-dependent Response of Coiled Coils: A Coarse-Grained Molecular Simulation StudyApr 26 2013In a recent work we proposed a coarse-grained methodology for studying the response of peptides when simulated at different values of pH; in this work we extend the methodology to analyze the pH-dependent behavior of coiled coils. This protein structure ... More
Coupling different levels of resolution in molecular simulationsJul 31 2009Aug 17 2009Simulation schemes that allow to change molecular representation in a subvolume of the simulation box while preserving the equilibrium with the surrounding introduce conceptual problems of thermodynamic consistency. In this work we present a general scheme ... More
Quantum-classical correspondence via a deformed kinetic operatorApr 16 2005We propose an approach to the quantum-classical correspondence based on a deformation of the momentum and kinetic operators of quantum mechanics. Making use of the factorization method, we construct classical versions of the momentum and kinetic operators ... More
Electronic Energy Functionals: Levy-Lieb principle within the Ground State Path Integral Quantum Monte CarloMay 29 2012We propose a theoretical/computational protocol based on the use of the Ground State (GS) Path Integral (PI) Quantum Monte Carlo (QMC) for the calculation of the kinetic and Coulomb energy density for a system of $N$ interacting electrons in an external ... More
Grand-canonical-like molecular-dynamics simulations by using an adaptive-resolution techniqueJan 21 2013In this work, we provide a detailed theoretical analysis, supported by numerical tests, of the reliability of the adaptive resolution simulation (AdResS) technique in sampling the Grand Canonical ensemble. We demonstrate that the correct density and radial ... More
Is there a third order phase transition for supercritical fluids?Jun 17 2013Dec 03 2013We prove that according to Molecular Dynamics (MD) simulations of liquid mixtures of Lennard-Jones (L-J) particles, there is no third order phase transition in the supercritical regime beyond Andrew's critical point. This result is in open contrast with ... More
Variational approach to dequantizationNov 08 2005Mar 28 2006We present a dequantization procedure based on a variational approach whereby quantum fluctuations latent in the quantum momentum are suppressed. This is done by adding generic local deformations to the quantum momentum operator which give rise to a deformed ... More
Simulation of Macromolecular Liquids with the Adaptive Resolution Molecular Dynamics TechniqueFeb 05 2016Jan 30 2017We extend the application of the adaptive resolution technique (AdResS) to liquid systems composed of alkane chains of different lengths. The aim of the study is to develop and test the modifications of AdResS required in order to handle the change of ... More
Simulation of Macromolecular Liquids with the Adaptive Resolution Molecular Dynamics TechniqueFeb 05 2016We extend the application of the adaptive resolution technique (AdResS) to liquid systems composed of alkane chains of different lengths. The aim of the study is to develop and test the modifications of AdResS required in order to handle the change of ... More
Adaptive Resolution Simulation as a Grand Canonical Molecular Dynamics Scheme: Principles, Applications and PerspectivesDec 15 2014We describe the adaptive resolution multiscale method AdResS. The conceptual evolution as well as the improvements of its technical efficiency are described step by step, with an explicit reference to current limitations and open problems.
Autocatalytic and cooperatively-stabilized dissociation of water on a stepped platinum surfaceNov 12 2012Water-metal interfaces are ubiquitous and play a key role in many chemical processes, from catalysis to corrosion. Whereas water adlayers on atomically flat transition metal surfaces have been investigated in depth, little is known about the chemistry ... More
Chemical potential of liquids and mixtures via Adaptive Resolution SimulationNov 27 2013Jul 03 2014We employ the adaptive resolution approach AdResS, in its recently developed Grand Canonical-like version (GC-AdResS) [Wang et al. Phys.Rev.X 3, 011018 (2013)], to calculate the excess chemical potential, $\mu^{ex}$, of various liquids and mixtures. We ... More
Exploring the conformational dynamics of alanine dipeptide in solution subjected to an external electric field: A nonequilibrium molecular dynamics simulationSep 05 2013Mar 12 2014In this paper, we investigate the conformational dynamics of alanine dipeptide under an external electric field by nonequilibrium molecular dynamics simulation. We consider the case of a constant and of an oscillatory field. In this context we propose ... More
Naturalness and Dark Matter in the BLSSMFeb 06 2017We study the naturalness properties of the $B-L$ Supersymmetric Standard Model (BLSSM) and compare them to those of the Minimal Supersymmetric Standard Model (MSSM) at both low (i.e., Large Hadron Collider) energies and high (i.e., unification) scales. ... More
${}^8$Be Decay Anomaly and Light $Z'$May 13 2019In this proceedings, we discuss a light (17 MeV) $Z'$ solution to the anomaly observed in the decay of Beryllium-8 by the Atomki collaboration. We detail an anomaly free model with minimal particle content which can satisfy all other experimental constraints ... More
Levy-Lieb principle: The bridge between the electron density of Density Functional Theory and the wavefunction of Quantum Monte CarloNov 27 2014The constrained-search principle introduced by Levy and Lieb, is proposed as a practical, though conceptually rigorous, link between Density Functional Theory (DFT) and Quantum Monte Carlo (QMC). The resulting numerical protocol realizes in practice the ... More
Levy-Lieb constrained-search formulation as a minimization of the correlation functionalApr 03 2007The constrained-search formulation of Levy and Lieb, which formally defines the exact Hohenberg-Kohn functional for any N-representable electron density, is here shown to be equivalent to the minimization of the correlation functional with respect to ... More
Some fundamental problems for an energy conserving adaptive resolution molecular dynamics schemeSep 17 2007Adaptive resolution molecular dynamics (MD) schemes allow for changing the number of degrees of freedom on the fly and preserve the free exchange of particles between regions of different resolution. There are two main alternatives on how to design the ... More
The Effective Actions of Pseudoscalar and Scalar Particles in Theories with Gauge and Conformal AnomaliesJan 28 2010We review recent work on the effective field theory description and the phenomenology of axion-like and scalar particles in models characterized by gauge and/or conformal anomalies.
On the upper bound of the electronic kinetic energy in terms of density functionalsApr 08 2005We propose a simple density functional expression for the upper bound of the kinetic energy for electronic systems. Such a functional is valid in the limit of slowly varying density, its validity outside this regime is discussed by making a comparison ... More
An analytic expression for the electronic correlation term of the kinetic functionalJan 16 2007We propose an analytic formula for the non-local Fisher information functional, or electronic kinetic correlation term, appearing in the expression of the kinetic density functional. Such an explicit formula is constructed on the basis of well-founded ... More
Equation of state of compressed matter: A simple statistical modelDec 16 2004We propose a simple approach for studying systems of compressed matter based on the Thomas-Fermi statistical model of single atom. The central point of our work is the development of the concept of ``statistical ionization'' by compression; in simple ... More
A procedure for calculating the many-particle Bohm quantum potentialDec 16 2004In a recent work, M.Kohout (M.Kohout, Int.J.Quant.Chem. 87, 12 2002) raised the important question of how to make a correct use of Bohm's approach for defining a quantum potential. In this work, by taking into account Kohout's results, we propose a general ... More
Bader's interatomic surface and Bohmian mechanicsAug 27 2002A Thomas-Fermi statistical analysis of Bader's interatomic surface developed in a previous work (L.Delle Site, Phys.Lett.A 286 61-64 (2001)) is here extended by considering exchange effects and electron density's inhomogeneity at basic level via Thomas-Fermi-Dirac-Weizsacker ... More
Adaptive resolution molecular dynamics simulation through coupling to an internal particle reservoirDec 14 2011Nov 11 2012For simulation studies of (macro) molecular liquids it would be of significant interest to be able to adjust or increase the level of resolution within one region of space, while allowing for the free exchange of molecules between open regions of different ... More
Water on Pt(111): the importance of proton disorderJan 23 2007The structure of a water adlayer on Pt(111) surface is investigated by extensive first principle calculations. Only allowing for proton disorder the ground state energy can be found. This results from an interplay between water/metal chemical bonding ... More
Molecular dynamics of open systems: construction of a mean-field particle reservoirFeb 19 2019The simulation of open molecular systems requires explicit or implicit reservoirs of energy and particles. Whereas full atomistic resolution is desired in the region of interest, there is some freedom in the implementation of the reservoirs. Here, we ... More
The momentum distribution of the homogeneous electron gasMay 11 2011May 17 2011We calculate the off-diagonal density matrix of the homogeneous electron gas at zero temperature using unbiased Reptation Monte Carlo for various densities and extrapolate the momentum distribution, and the kinetic and potential energies to the thermodynamic ... More
Molecular Dynamics in a Grand Ensemble: Bergmann-Lebowitz model and Adaptive Resolution SimulationDec 02 2014May 27 2015This article deals with the molecular dynamics simulation of open systems that can exchange energy and matter with a reservoir; the physics of the reservoir and its interactions with the system are described by the model introduced by Bergmann and Lebowitz.Despite ... More
Adaptive Resolution Simulation of Liquid WaterNov 21 2006Dec 06 2006We present a multiscale simulation of liquid water where a spatially adaptive molecular resolution procedure allows for changing on-the-fly from a coarse-grained to an all-atom representation. We show that this approach leads to the correct description ... More
Modeling Diffusive Dynamics in Adaptive Resolution Simulation of Liquid WaterOct 01 2007We present a dual-resolution molecular dynamics (MD) simulation of liquid water employing a recently introduced Adaptive Resolution Scheme (AdResS). The spatially adaptive molecular resolution procedure allows for changing from a coarse-grained to an ... More
Adaptive Resolution Molecular Dynamics Technique: Down to the EssentialJun 26 2018We investigate the role of the thermodynamic (TD) force, as an essential and sufficient technical ingredient for an efficient and accurate adaptive resolution algorithm. Such a force applied in the coupling region of an adaptive resolution Molecular Dynamics ... More
Sneutrino Dark Matter, Constraints and PerspectivesApr 20 2018The prevalent Dark Matter (DM) candidate of the (B-L) Supersymmetric Standard Model (BLSSM) is the Right Handed (RH) sneutrino. In this work we assess the ability of ground and space based experiments to establish the nature of this particle, through ... More
Thomas-Fermi generalized approach for studying systems under pressureDec 16 2004In a previous work one of the authors proposed a simple model for studying systems under pressure based on the Thomas-Fermi (TF) model of single atom. In this work we intend to extend the previous work to more general Thomas-Fermi models where electronic ... More
Classical-path integral adaptive resolution in molecular simulation: towards a smooth quantum-classical couplingFeb 22 2010Simulations that couple different classical molecular models in an adaptive way by changing the number of degrees of freedom on the fly, are available within reasonably consistent theoretical frameworks. The same does not occur when it comes to classical-quantum ... More
The Standard Model in a Weak Gravitational Background. Dilatons, Scale Anomalies and Conformal MethodsAug 01 2013The principal goal of the physics of the fundamental interactions is to provide a consistent description of the nature of the subnuclear forces, which manifest in our universe, together with the gravitational force, in a unified framework. This attempt, ... More
Massless Scalar Degrees of Freedom in QCD and in the Electroweak Sector from the Trace AnomalyAug 31 2012Sep 05 2012The interaction of QCD and electroweak sector with gravity is characterized by the generation of a massless pole in a specific form factor present in the 1-loop effective action. We briefly illustrate how to single out this behaviour in perturbation theory, ... More
Dilaton Interactions in QCD and in the Electroweak Sector of the Standard ModelAug 31 2012Sep 05 2012We overview the structure of the effective action involving a dilaton and a Higgs in the Standard Model, which has been computed recently for the neutral currents sector. We discuss the role of the dilatation current ($J_D$) and of an effective degree ... More
Classical kinetic energy, quantum fluctuation terms and kinetic-energy functionalsSep 17 2006Apr 08 2007We employ a recently formulated dequantization procedure to obtain an exact expression for the kinetic energy which is applicable to all kinetic-energy functionals. We express the kinetic energy of an N-electron system as the sum of an N-electron classical ... More
Flow boundary conditions for chain-end adsorbing polymer blendsJul 18 2005Using the phenol-terminated polycarbonate blend as an example, we demonstrate that the hydrodynamic boundary conditions for a flow of an adsorbing polymer melt are extremely sensitive to the structure of the epitaxial layer. Under shear, the adsorbed ... More
Dynamic surface decoupling in a sheared polymer meltFeb 24 2005We propose that several mechanisms contribute to friction in a polymer melt adsorbed at a structured surface. The first one is the well known disentanglement of bulk polymer chains from the surface layer. However, if the surface is ideal at the atomic ... More
Polymers near Metal Surfaces: Selective Adsorption and Global ConformationsAug 19 2002Sep 20 2002We study the properties of a polycarbonate melt near a nickel surface as a model system for the interaction of polymers with metal surfaces by employing a multiscale modeling approach. For bulk properties a suitably coarse grained bead spring model is ... More
Trilinear Gauge Interactions in Extensions of the Standard Model and UnitarityMay 27 2009We summarize recent work on the characterization of anomaly poles in connection with the field-theory interpretation of the Green-Schwarz mechanism of anomaly cancellation and on their effective field theories, stressing on the properties of the anomaly ... More
Gravity and the Neutral Currents: Effective Interactions from the Trace AnomalyFeb 22 2011May 03 2011We present a complete study of the one graviton-two neutral gauge bosons vertex at 1-loop level in the electroweak theory. This vertex provides the leading contribution to the interaction between the Standard Model and gravity, mediated by the trace anomaly, ... More
The Trace Anomaly and the Couplings of QED and QCD to GravityJul 13 2010Jul 26 2010We report on the computation of the effective actions describing the interaction of gravity both for an abelian and a non-abelian gauge theory, mediated by the trace anomaly.
Trace Anomaly, Massless Scalars and the Gravitational Coupling of QCDMay 23 2010Aug 11 2010The anomalous effective action describing the coupling of gravity to a non-abelian gauge theory can be determined by a variational solution of the anomaly equation, as shown by Riegert long ago. It is given by a nonlocal expression, with the nonlocal ... More
On the stability of the electroweak vacuum in the presence of low-scale seesaw modelsJun 10 2015Jun 16 2015The scale of neutrino masses and the Planck scale are separated by more than twenty-seven order of magnitudes. However, they can be linked by imposing the stability of the electroweak (EW) vacuum. The crucial ingredient is provided by the generation of ... More
Constraints on Abelian Extensions of the Standard Model from Two-Loop Vacuum Stability and $U(1)_{B-L}$Oct 08 2015Aug 02 2016We present a renormalization group study of the scalar potential in a minimal $U(1)_{B-L}$ extension of the Standard Model involving one extra heavier Higgs and three heavy right-handed neutrinos with family universal B-L charge assignments. We implement ... More
Sum rules and spectral density flow in QCD and in superconformal theoriesSep 17 2014We discuss the signature of the anomalous breaking of the superconformal symmetry in $\mathcal{N}=1$ super Yang Mills theory and its manifestation in the form of anomaly poles. Moreover, we describe the massive deformations of the $\mathcal{N}=1$ theory ... More
Conformal anomaly actions for dilaton interactionsSep 15 2014Oct 07 2014We discuss, in conformally invariant field theories such as QCD with massless fermions, a possible link between the perturbative signature of the conformal anomaly, in the form of anomaly poles of the 1-particle irreducible effective action, and its description ... More
Vacuum Stability in U(1)-Prime Extensions of the Standard Model with TeV Scale Right Handed NeutrinosJul 31 2014Sep 02 2014We investigate a minimal $U(1)'$ extension of the Standard Model with one extra complex scalar and generic gauge charge assignments. We use a type-I seesaw mechanism with three heavy right handed neutrinos to illustrate the constraints on the charges, ... More
On the fate of the Standard Model at finite temperatureJul 24 2015Dec 21 2015In this paper we revisit and update the computation of thermal corrections to the stability of the electroweak vacuum in the Standard Model. At zero temperature, we make use of the full two-loop effective potential, improved by three-loop beta functions ... More
Anomaly Poles as Common Signatures of Chiral and Conformal AnomaliesSep 24 2009Nov 22 2009One feature of the chiral anomaly, analyzed in a perturbative framework, is the appearance of massless poles which account for it. They are identified by a spectral analysis of the anomaly graph and are usually interpreted as being of an infrared origin. ... More
Stability constraints of the scalar potential in extensions of the Standard Model with TeV scale right handed neutrinosNov 26 2014We investigate the stability of the scalar potential in a minimal $U(1)'$ extension of the Standard Model augmented by an extra complex scalar and three right handed neutrinos. We consider a type-I seesaw scenario for the generation of the small neutrino ... More
Three and Four Point Functions of Stress Energy Tensors in D=3 for the Analysis of Cosmological Non-GaussianitiesSep 29 2012We compute the correlation functions of 3 and 4 stress energy tensors $(T)$ in D=3 in free field theories of scalars, abelian gauge fields, and fermions, which are relevant in the analysis of cosmological non-gaussianities. These correlators appear in ... More
Explanation of the Beryllium Anomaly in a $U(1)'$-Extended 2-Higgs Doublet ModelAug 29 2017We consider an extension of the Standard Model with an extra gauged $U(1)'$ symmetry in presence of a 2-Higgs Doublet Model structure of the scalar sector. We show that this scenario is able to explain the anomaly observed by the Atomki collaboration ... More
Explanation of the 17 MeV Atomki Anomaly in a $U(1)^\prime$-Extended 2-Higgs Doublet ModelApr 11 2017Feb 15 2018Motivated by an anomaly observed in the decay of an excited state of Beryllium by the Atomki collaboration, we study an extension of the Standard Model with a gauged $U(1)'$ symmetry in presence of a 2-Higgs Doublet Model structure of the Higgs sector. ... More
The Trace Anomaly and the Gravitational Coupling of an Anomalous U(1)Mar 20 2010Dec 24 2010We extend a previous computation of the TJJ correlator, involving the energy-momentum tensor of an abelian gauge theory and two vector currents, to the case of mixed axial-vector/vector currents. The study is performed in analogy to the case of the $AVV$ ... More
Electromagnetic interferences from plasmas generated in meteoroids impactsApr 23 1998Dec 16 2001It is shown that the plasma, generated during an impact of a meteoroid with an artificial satellite, can produce electromagnetic radiation below the microwave frequency range. This interference is shown to exceed local noise sources and might disturb ... More
On the atmospheric fragmentation of small asteroidsDec 12 2000Dec 13 2000It is known, from observational data recorded from airbursts, that small asteroids breakup at dynamical pressures lower than their mechanical strength. This means that actual theoretical models are inconsistent with observations. In this paper, we present ... More
Where the "it from bit" come from?Jun 03 2013In his 1989 essay, John Archibald Wheeler has tried to answer the eternal question of existence. He did it by searching for links between information, physics, and quanta. The main concept emerging from his essay is that "every physical quantity, every ... More
The Blandford-Znajek theory revisitedMay 14 2012Jan 15 2016The Blandford-Znajek theory (1977) is generally studied to understand the generation of powerful relativistic jets. However, it could also give important insights about the feedback between a rotating black hole, its ergosphere, and a surrounding accretion ... More
Notes on the data analysis in high-energy astrophysicsOct 12 2009These notes were originally prepared as additional material for the lessons I have given at the summer school Gamma-ray Astrophysics and Multifrequency: Data analysis and astroparticle problems, organized by the Department of Physics of the University ... More
The scientific construction of the worldJul 15 2015There is no mysterious link between mathematics and physics, because both of them are human inventions designed to study the world.
Accretion and jet power in active galactic nucleiJun 27 2011Aug 24 2011The classical diagrams of radio loudness and jet power as a function of mass and accretion rate of the central spacetime singularity in active galactic nuclei are reanalyzed by including the data of the recently discovered powerful relativistic jets in ... More
Algebraic equivalence between certain models for superfluid--insulator transitionFeb 25 2000Dec 12 2000Algebraic contraction is proposed to realize mappings between models Hamiltonians. This transformation contracts the algebra of the degrees of freedom underlying the Hamiltonian. The rigorous mapping between the anisotropic $XXZ$ Heisenberg model, the ... More
Redshift Surveys and Large--Scale StructureJan 18 1996I review the present status of the mapping of the large-scale structure of the Universe through wide-angle redshift surveys. In the first part of the paper, I discuss the current state of the art, describing in some detail the recently completed ESO Slice ... More
The ESO All-Southern-Sky Redshift Survey of ROSAT Clusters of GalaxiesOct 11 1994We discuss the rationale and the present status of a large redshift survey aiming at measuring distances for all the clusters of galaxies detected by the ROSAT X--ray All--Sky Survey in the southern hemisphere, with flux larger than $\sim 2\times 10^{-12}$ ... More
A simple model of scientific progress - with examplesApr 23 2016One of the main goals of scientific research is to provide a description of the empirical data which is as accurate and comprehensive as possible, while relying on as few and simple assumptions as possible. In this paper, I propose a definition of the ... More
Finite size emptiness formation probability of the XXZ spin chain at $Δ=-1/2$Oct 11 2011In this paper we compute the Emptiness Formation Probability of a (twisted-) periodic XXZ spin chain of finite length at $\Delta=-1/2$, thus proving the formulae conjectured by Razumov and Stroganov \cite{raz-strog1, raz-strog2}. The result is obtained ... More
Derived equivalence and fibrations over curves and surfacesMar 23 2018Oct 26 2018We prove that the bounded derived category of coherent sheaves reconstructs the isomorphism classes of fibrations of a smooth projective complex variety onto smooth curves of genus g>1. Moreover we extend this invariance to special classes of fibrations ... More
On the existence of solutions for the Maxwell equationsMay 12 2009Mathematical proofs are presented concerning the existence of solutions of the Maxwell equations with suitable boundary conditions. In particular it is stated that the well known "delayed potentials" provide effective solutions of the equations, under ... More
Derived Semidistributive LatticesAug 13 2007Jul 21 2008For L a finite lattice, let C(L) denote the set of pairs g = (g_0,g_1) such that g_0 is a lower cover of g_1 and order it as follows: g <= d iff g_0 <= d_0, g_1 <= d_1, but not g_1 <= d_0. Let C(L,g) denote the connected component of g in this poset. ... More
A bimodule structure for the bounded cohomology of commutative local ringsNov 21 2018Stable cohomology is a generalization of Tate cohomology to associative rings, first defined by Pierre Vogel. For a commutative local ring $R$ with residue field $k$, stable cohomology modules $\widehat{\mathrm{Ext}}{\vphantom E}^{n}_R\;(k,k)$, defined ... More
The AGN tori sizes: a remark on astro-ph/0512025 by Moshe ElitzurDec 05 2005We point out that in Granato & Danese 1994 and Granato et al. 1997 we predicted maximum observable sizes for the putative torus in NGC1068 of 10-20 pc, not "hundreds of parsecs" as stated by M. Elitzur in astro-ph/0512025.
The Lefschetz thimble and the sign problemDec 25 2015In this talk I review the proposal to formulate quantum field theories (QFTs) on a Lefschetz thimble, which was put forward to enable Monte Carlo simulations of lattice QFTs affected by sign problem. First I will review the theoretical justification of ... More
Science and IllusionsApr 23 2016It is mostly agreed that Popper's criterion of falsifiability fails to provide a useful demarcation between science and pseudo-science, because ad-hoc assumptions are always able to save any theory that conflicts with the empirical data (a.k.a. the Duhem-Quine ... More
A behavioural approach to obstacle avoidance for mobile manipulators based on distributed sensingFeb 09 2015A reactive obstacle avoidance method for mobile manipulators is presented. The objectives of the developed algorithm are twofold. The first one is to find a trajectory in the configuration space of a mobile manipulator so as to follow a given trajectory ... More
Modeling sorption of emerging contaminants in biofilmsJun 05 2017A mathematical model for emerging contaminants sorption in multispecies biofilms, based on a continuum approach and mass conservation principles is presented. Diffusion of contaminants within the biofilm is described using a diffusion-reaction equation. ... More
Microlensing towards the LMC revisited by adopting a non-Gaussian velocity distribution for the sourcesJan 28 2009We discuss whether the Gaussian is a reasonable approximation of the velocity distribution of stellar systems that are not spherically distributed. By using a non-Gaussian velocity distribution to describe the sources in the Large Magellanic Cloud (LMC), ... More
On the dynamic programming approach for the 3D Navier-Stokes equationsSep 14 2006The dynamic programming approach for the control of a 3D flow governed by the stochastic Navier-Stokes equations for incompressible fluid in a bounded domain is studied. By a compactness argument, existence of solutions for the associated Hamilton-Jacobi-Bellman ... More
Measure-valued equations for Kolmogorov operators with unbounded coefficientsJul 21 2007Given a real and separable Hilbert space H we consider the measure-valued equation \begin{equation*} \int_H\phi(x)\mu_t(dx)- \int_H\phi(x)\mu(dx)= \int_0^t(\int_HK_0\phi(x)\mu_s(dx))ds, \end{equation*} where K_0 is the Kolmogorov differential operator ... More