Results for "D. Stam"

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Spectropolarimetric signatures of Earth-like extrasolar planetsJul 26 2007We present results of numerical simulations of the flux (irradiance), F, and the degree of polarization (i.e. the ratio of polarized to total flux), P, of light that is reflected by Earth-like extrasolar planets orbiting solar-type stars, as functions ... More
Modeled flux and polarisation signals of horizontally inhomogeneous exoplanets, applied to Earth--like planetsOct 11 2012We present modeled flux and linear polarisation signals of starlight that is reflected by spatially unresolved, horizontally inhomogeneous planets and discuss the effects of including horizontal inhomogeneities on the flux and polarisation signals of ... More
Flux and polarization signals of spatially inhomogeneous gaseous exoplanetsJul 03 2013We present numerically calculated, disk--integrated, spectropolarimetric signals of starlight that is reflected by vertically and horizontally inhomogeneous gaseous exoplanets. We include various spatial features that are present on Solar System's gaseous ... More
The influence of forward-scattered light in transmission measurements of (exo)planetary atmospheresAug 14 2012[Abridged] The transmission of light through a planetary atmosphere can be studied as a function of altitude and wavelength using stellar or solar occultations, giving often unique constraints on the atmospheric composition. For exoplanets, a transit ... More
Blue, white, and red ocean planets - Simulations of orbital variations in flux and polarization colorsApr 18 2019Apr 26 2019An exoplanet's habitability will depend strongly on the presence of liquid water. Flux and/or polarization measurements of starlight that is reflected by exoplanets could help to identify exo-oceans. We investigate which broadband spectral features in ... More
Characterizing exoplanetary atmospheres through infrared polarimetryAug 05 2011Planets can emit polarized thermal radiation, just like brown dwarfs. We present calculated thermal polarization signals from hot exoplanets, using an advanced radiative transfer code that fully includes all orders of scattering by gaseous molecules and ... More
Looking for the rainbow on exoplanets covered by liquid and icy water cloudsNov 06 2012Looking for the primary rainbow in starlight that is reflected by exoplanets appears to be a promising method to search for liquid water clouds in exoplanetary atmospheres. Ice water clouds, that consist of water crystals instead of water droplets, could ... More
Unconstrained Variables and Equivalence Relations for Lattice Gauge TheoriesNov 18 2010Aug 11 2011We write the partition function for a lattice gauge theory, with compact gauge group, exactly in terms of unconstrained variables and show that, in the mean field approximation, the dynamics of pure gauge theories, invariant under compact, continuous,groups ... More
Second Order Phase Transition in Anisotropic Lattice Gauge Theories with Extra DimensionsOct 25 2010Field theories with extra dimensions live in a limbo. While their classical solutions have been the subject of considerable study, their quantum aspects are difficult to control. A special class of such theories are anisotropic gauge theories. The anisotropy ... More
Anomaly cancellation for anisotropic lattice fields with extra dimensionsJan 12 2010The current flow from the bulk is due to the anomaly on the brane-but the absence of current flow is not, necessarily, due to anomaly cancellation, but to the absence of the chiral zero modes themselves, due to the existence of the layered phase. This ... More
Critical Properties of Stochastic Cellular Automata}Jun 01 1994We study the effect of mixing two rules on the dynamics of one-dimensional cellular automata by large scale numerical simulations. We calculate the decay of the magnetization for the Domany-Kinzel automaton (XOR/AND mixing) to its equilibrium value in ... More
How quantum mechanics probes superspaceJun 27 2016We study the relation between the partition function of a non--relativistic particle, that describes the equilibrium fluctuations implicitly, and the partition function of the same system, deduced from the Langevin equation, that describes the fluctuations ... More
The influence of non-isotropic scattering of thermal radiation on spectra of brown dwarfs and hot exoplanetsMay 16 2011Jun 03 2011(abridged) We calculate near-infrared thermal emission spectra using a doubling-adding radiative transfer code, which includes scattering by clouds and haze. Initial temperature profiles and cloud optical depths are taken from the drift-phoenix brown ... More
Observing the Earth as an exoplanet with LOUPE, the Lunar Observatory for Unresolved Polarimetry of EarthMar 01 2012The detections of small, rocky exoplanets have surged in recent years and will likely continue to do so. To know whether a rocky exoplanet is habitable, we have to characterise its atmosphere and surface. A promising characterisation method for rocky ... More
Scattering matrices and expansion coefficients of Martian analogue palagonite particlesSep 16 2008We present measurements of ratios of elements of the scattering matrix of Martian analogue palagonite particles for scattering angles ranging from 3 to 174 degrees and a wavelength of 632.8 nm. To facilitate the use of these measurements in radiative ... More
Using polarimetry to retrieve the cloud coverage of Earth-like exoplanetsAug 23 2017Context. Clouds have already been detected in exoplanetary atmospheres. They play crucial roles in a planet's atmosphere and climate and can also create ambiguities in the determination of atmospheric parameters such as trace gas mixing ratios. Knowledge ... More
Atmospheric characterization of cold exoplanets using a 1.5-m coronagraphic space telescopeMar 13 2012Context. High-contrast imaging is currently the only available technique for the study of the thermodynamical and compositional properties of exoplanets in long-period orbits. The SPICES project is a coronagraphic space telescope dedicated to the spectro-polarimetric ... More
The Herschel-SPIRE submillimetre spectrum of MarsMay 25 2010We have obtained the first continuous disk averaged spectrum of Mars from 450 to 1550 Ghz using the Herschel-SPIRE Fourier Transform Spectrometer. The spectrum was obtained at a constant resolution of 1.4 GHz across the whole band. The flux from the planet ... More
Large atom number Bose-Einstein condensate of sodiumSep 04 2006We describe the setup to create a large Bose-Einstein condensate containing more than 120x10^6 atoms. In the experiment a thermal beam is slowed by a Zeeman slower and captured in a dark-spot magneto-optical trap (MOT). A typical dark-spot MOT in our ... More
Excitations of Bose-Einstein condensates in a one-dimensional periodic potentialJan 13 2009We report on the experimental investigation of the response of a three-dimensional Bose-Einstein condensate (BEC) in the presence of a one-dimensional (1D) optical lattice. By means of Bragg spectroscopy we probe the band structure of the excitation spectrum ... More
Circular polarization signals of cloudy (exo)planetsMay 22 2018The circular polarization of light that planets reflect is often neglected because it is very small compared to the linear polarization. It could, however, provide information on a planet's atmosphere and surface, and on the presence of life, because ... More
Quantum Magnets and Matrix Lorenz SystemsApr 23 2015The Landau--Lifshitz--Gilbert equations for the evolution of the magnetization, in presence of an external torque, can be cast in the form of the Lorenz equations and, thus, can describe chaotic fluctuations. To study quantum effects, we describe the ... More
Quantum cat map dynamics on AdS$_2$Aug 28 2016Sep 29 2016We present a toy model for the chaotic unitary scattering of single particle wave packets on the radial AdS$_2$ geometry of extremal BH horizons. Based on our recent work on the discretization of the AdS$_2$ space-time, which describes a finite and random ... More
Colored-noise magnetization dynamics: from weakly to strongly correlated noiseNov 06 2015Statistical averaging theorems allow us to derive a set of equations for the averaged magnetization dynamics in the presence of colored (non-Markovian) noise. The non-Markovian character of the noise is described by a finite auto-correlation time, tau, ... More
A group action principle for Nambu dynamics of spin degrees of freedomJan 10 2018We describe a formulation of the group action principle, for linear Nambu flows, that explicitly takes into account all the defining properties of Nambu mechanics and illustrate its relevance by showing how it can be used to describe the off-shell states ... More
Probing magneto-elastic phenomena through an effective spin-bath coupling modelSep 16 2018Jan 17 2019A phenomenological model is constructed, that captures the effects of coupling magnetic and elastic degrees of freedom, in the presence of external, stochastic perturbations, in terms of the interaction of magnetic moments with a bath, whose individual ... More
Non-blinking single-photon emitters in silicaSep 24 2015Samples for single-emitter spectroscopy are usually prepared by spin-coating a dilute solution of emitters on a microscope cover slip of silicate based glass (such as quartz). Here, we show that both borosilicate glass and quartz contain intrinsic defect ... More
Nambu mechanics for stochastic magnetization dynamicsOct 14 2016The Landau-Lifshitz-Gilbert (LLG) equation describes the dynamics of a damped magnetization vector that can be understood as a generalization of Larmor spin precession. The LLG equation cannot be deduced from the Hamiltonian framework, by introducing ... More
Coupling magneto-elastic Lagrangians to spin transfer torque sourcesNov 21 2017Jun 13 2018The consequences of coupling magnetic and elastic degrees of freedom, where spins and deformations are carried by point-like objects subject to local interactions, are studied, theoretically and by detailed numerical simulations. From the constrained ... More
The O2 A-band in fluxes and polarization of starlight reflected by Earth-like exoplanetsApr 20 2017Earth-like, potentially habitable exoplanets are prime targets in the search for extraterrestrial life. Information about their atmosphere and surface can be derived by analyzing light of the parent star reflected by the planet. We investigate the influence ... More
The quantum cat map on the modular discretization of extremal black hole horizonsAug 28 2016May 29 2018Based on our recent work on the discretization of the radial AdS$_2$ geometry of extremal BH horizons,we present a toy model for the chaotic unitary evolution of infalling single particle wave packets. We construct explicitly the eigenstates and eigenvalues ... More
Long range correlations and folding angle in polymers with applications to α-helical proteinsJun 22 2013The conformational complexity of linear polymers far exceeds that of point-like atoms and molecules. Polymers can bend, twist, even become knotted. Thus they may also display a much richer phase structure than point particles. But it is not very easy ... More
Non-Markovian magnetization dynamics for uniaxial nanomagnetsNov 05 2015A stochastic approach for the description of the time evolution of the magnetization of nanomagnets is proposed, that interpolates between the Landau-Lifshitz-Gilbert and the Landau-Lifshitz-Bloch approximations, by varying the strength of the noise. ... More
Blue, white, and red ocean planets - Simulations of orbital variations in flux and polarization colorsApr 18 2019An exoplanet's habitability will depend strongly on the presence of liquid water. Flux and/or polarization measurements of starlight that is reflected by exoplanets could help to identify exo-oceans. We investigate which broadband spectral features in ... More
Finite-dimensional colored fluctuation-dissipation theorem for spin systemsOct 05 2016When nano-magnets are coupled to random external sources, their magnetization becomes a random variable, whose properties are defined by an induced probability density, that can be reconstructed from its moments, using the Langevin equation, for mapping ... More
Super Earth Explorer: A Coronagraphic Off-Axis Space TelescopeNov 24 2008Nov 25 2008The Super-Earth Explorer is an Off-Axis Space Telescope (SEE-COAST) designed for high contrast imaging. Its scientific objective is to make the physico-chemical characterization of exoplanets possibly down to 2 Earth radii >. For that purpose it will ... More
Quantum cat map dynamics on AdS$_2$Aug 28 2016We present a toy model for the chaotic unitary scattering of single particle wave packets on the radial AdS$_2$ geometry of extremal BH horizons. Based on our recent work for the discretization of the AdS$_2$ space-time, which describes a finite and random ... More
Closing the hierarchy for non-Markovian magnetization dynamicsJun 01 2015We propose a stochastic approach for the description of the time evolution of the magnetization of nanomagnets, that interpolates between the Landau--Lifshitz--Gilbert and the Landau--Lifshitz--Bloch approximations, by varying the strength of the noise. ... More
Nambu mechanics for stochastic magnetization dynamicsOct 14 2016Jan 19 2017The Landau-Lifshitz-Gilbert (LLG) equation describes the dynamics of a damped magnetization vector that can be understood as a generalization of Larmor spin precession. The LLG equation cannot be deduced from the Hamiltonian framework, by introducing ... More
Probing the hue of the stochastic magnetization dynamicsJul 06 2016The Fokker--Planck equation describes the evolution of a probability distribution towards equilibrium--the flow parameter is the equilibration time. Assuming the distribution remains normalizable for all times, it is equivalent to an open hierarchy of ... More
A functional calculus for the magnetization dynamicsJun 07 2016A functional calculus approach is applied to the derivation of evolution equations for the moments of the magnetization dynamics of systems subject to stochastic fields. It allows us to derive a general framework for obtaining the master equation for ... More
Chaotic Information Processing by Extremal Black HolesApr 02 2015We review an explicit regularization of the AdS$_2$/CFT$_1$ correspondence, that preserves all isometries of bulk and boundary degrees of freedom. This scheme is useful to characterize the space of the unitary evolution operators that describe the dynamics ... More
Force generation by Myosin II Filaments in Compliant NetworksApr 12 2014Jul 08 2014Myosin II isoforms with varying mechanochemistry and filament size interact with filamentous actin (F-actin) networks to generate contractile forces in cells. How their properties control force production in environments with varying stiffness is poorly ... More
PyMieDAP: a Python--Fortran tool to compute fluxes and polarization signals of (exo)planetsApr 23 2018PyMieDAP (the Python Mie Doubling-Adding Programme) is a Python--based tool for computing the total, linearly, and circularly polarized fluxes of incident unpolarized sun- or starlight that is reflected by, respectively, Solar System planets or moons, ... More
Position measurement of non-integer OAM beams with structurally invariant propagationJul 19 2012Sep 18 2012We present a design to generate structurally propagation invariant light beams carrying non-integer orbital angular momentum (OAM) using Hermite-Laguerre-Gaussian (HLG) modes. Different from previous techniques, the symmetry axes of our beams are fixed ... More
Population Synthesis of Radio Pulsars in the Fermi EraDec 18 2009Dec 20 2009We present results of our pulsar population synthesis of normal pulsars from the Galactic disk using our previously developed Monte-Carlo code. From our studies of observed radio pulsars that have clearly identifiable core and cone components, in which ... More
Traces of exomoons in computed flux and polarization phase curves of starlight reflected by exoplanetsJul 26 2018Context: Detecting moons around exoplanets is a major goal of current and future observatories. Moons are suspected to influence rocky exoplanet habitability, and gaseous exoplanets in stellar habitable zones could harbour abundant and diverse moons to ... More
Using SPICA Space Telescope to characterize ExoplanetsSep 01 2008Sep 15 2008We present the 3.5m SPICA space telescope, a proposed Japanese-led JAXA-ESA mission scheduled for launch around 2017. The actively cooled (<5 K), single aperture telescope and monolithic mirror will operate from ~3.5 to ~210 um and will provide superb ... More
Ultraviolet Spectropolarimetry as a Tool for Understanding the Diversity of Exoplanetary AtmospheresMar 14 2019Mar 15 2019The polarization state of starlight reflected by a planetary atmosphere uniquely reveals coverage, particle size, and composition of aerosols as well as changing cloud patterns. It is not possible to obtain a comparable level of detailed from flux-only ... More
Polarized scattered light from self-luminous exoplanets. Three-dimensional scattering radiative transfer with ARTESJun 28 2017Nov 08 2018Direct imaging has paved the way for atmospheric characterization of young and self-luminous gas giants. Scattering in a horizontally-inhomogeneous atmosphere causes the disk-integrated polarization of the thermal radiation to be linearly polarized, possibly ... More
Ultraviolet Spectropolarimetry as a Tool for Understanding the Diversity of Exoplanetary AtmospheresMar 14 2019The polarization state of starlight reflected by a planetary atmosphere uniquely reveals coverage, particle size, and composition of aerosols as well as changing cloud patterns. It is not possible to obtain a comparable level of detailed from flux-only ... More
Noise correlation spectroscopy of the broken order of a Mott insulating phaseMar 13 2008We use a two-color lattice to break the homogeneous site occupation of an atomic Mott Insulator of bosonic 87Rb. We detect the disruption of the ordered Mott domains via noise correlation analysis of the atomic density distribution after time-of-flight. ... More
A lattice model approach to the morphology formation from ternary mixtures during the evaporation of one componentAug 28 2018Stimulated by experimental evidence in the field of solution--born thin films, we study the morphology formation in a three state lattice system subjected to the evaporation of one component. The practical problem that we address is the understanding ... More
Diversity among other worlds: characterization of exoplanets by direct detectionNov 15 2008Dec 04 2008The physical characterization of exoplanets will require to take spectra at several orbital positions. For that purpose, a direct imaging capability is necessary. Direct imaging requires an efficient stellar suppression mechanism, associated with an ultrasmooth ... More
Spectral and Temporal Variability of Earth Observed in PolarizationNov 29 2018We present a comprehensive set of spectropolarimetric observations of Earthshine as obtained by FORS2 at the VLT for phase angles from 50degree to 135degree (Sun-Earth-Moon angle), covering a spectral range from 430nm to 920nm. The degree of polarization ... More
Characterizing Exoplanets in the Visible and Infrared: A Spectrometer Concept for the EChO Space MissionMay 14 2013Transit-spectroscopy of exoplanets is one of the key observational techniques to characterize the extrasolar planet and its atmosphere. The observational challenges of these measurements require dedicated instrumentation and only the space environment ... More
Water production in comet 81P/Wild 2 as determined by Herschel/HIFIJul 01 2010The high spectral resolution and sensitivity of Herschel/HIFI allows for the detection of multiple rotational water lines and accurate determinations of water production rates in comets. In this letter we present HIFI observations of the fundamental 110-101 ... More
The Hera Saturn Entry Probe MissionOct 26 2015The Hera Saturn entry probe mission is proposed as an M--class mission led by ESA with a contribution from NASA. It consists of one atmospheric probe to be sent into the atmosphere of Saturn, and a Carrier-Relay spacecraft. In this concept, the Hera probe ... More
Resonant superradiant backward-scattering as a source for many-particle entanglementJul 10 2007We investigate the atom pair production by superradiant backward-scattering from a Bose-Einstein condensate. By driving the superradiant process with two frequencies we can extend both the range of pulse duration and intensity by two orders of magnitude ... More
Cen A persistence and Virgo absence versus updated maps to understand UHECR natureDec 31 2010Ultra High Cosmic Rays (UHECR) should be tracing their sources, making a new astronomy. Their events counting are finally growing, by Auger experiment, into cosmic sky. Their map should follow the mass distribution in a narrow cosmic volume (the GZK cut ... More
Deep Core muon neutrino rate and anisotropy by mixing and CPT violationDec 23 2010Neutrinos are allowed to mix and to oscillate among their flavor. Muon and tau in particular oscillate at largest values.Last Minos experiment claimed possible difference among their matter and anti-matter masses, leading to a first violation of the most ... More
Achievements and Mirages in Uhecr and Neutrino AstronomyMay 11 2009Photon Astronomy ruled the last four centuries while wider photon band ruled last radio-X-Gamma century of discovery. Present decade may see the rise and competition of UHECR and UHE Neutrino Astronomy. Tau Neutrino may win and be the first flavor revealed. ... More
An apparent GRBs evolution around us or a sampling of thin GRB beaming jets?Oct 13 2009Oct 14 2009The gamma ray burst apparent average isotropic power versus their red-shift of all known GRB (Sept.2009) is reported. It calls for an unrealistic Gamma Ray Burst Evolution around us or it just probe the need of a very thin gamma precession-jet model. ... More
Inconsistence of super-luminal Cern-Opera neutrino speed with observed SN1987A burst and neutrino mixing for any imaginary neutrino massSep 25 2011Mar 05 2012We tried to fit in any way the recent Opera-Cern claims of a neutrino super-luminal speed with observed Supernova SN1987A neutrino burst and all (or most) neutrino flavor oscillation. We considered three main frame-works: (1) A tachyon imaginary neutrino ... More
Some surface subgroups survive surgeryApr 07 2001It is shown that with finitely many exceptions, the fundamental group obtained by Dehn surgery on a one cusped hyperbolic 3-manifold contains the fundamental group of a closed surface.
Intrinsic Properties of the <z>=2.7 Lyman Alpha Forest from Keck Spectra of QSO HS 1946+7658Jan 27 1997Feb 20 1997We present the highest quality Lyman Alpha forest spectra published to date, from the QSO HS 1946+7658. The distribution of H I column densities is a power law of slope -1.5 from Log N = 12.1 - 14. This power law can extend to N = 0, because lines weaker ... More
Possible flakes of molecular hydrogen in the early UniverseNov 18 2002The thermochemistry of H2 and HD in non-collapsed, non-reionized primordial gas up to the end of the dark age is investigated with recent radiation-matter and chemical reaction rates taking into account the efficient coolant HD, and the possibility of ... More
The category of singularities as a crystal and global Springer fibersDec 14 2014May 12 2015We prove the "Gluing Conjecture" on the spectral side of the categorical geometric Langlands correspondence. The key tool is the structure of crystal on the category of singularities, which allows to reduce the conjecture to the question of homological ... More
The spin-1 ladder : A bosonization studyAug 16 1999We construct a field-theoretic description of two coupled spin-1 Heisenberg chains, starting with the known representation of a single spin-1 chain in terms of Majorana fermions (or Ising models). After reexamining the bosonization rules for two Ising ... More
Ginzburg-Landau equations for superconducting quark matter in neutron starsJun 19 2000May 18 2002We investigate magnetic properties of color superconducting quark matter within a Ginzburg-Landau approach. The simultaneous coupling of the quark fields to gluonic and electromagnetic gauge fields leads to rotated electromagnetism with a massive (Higgsed) ... More
13CO(1-0) and 12CO(2-1) in the center of the barred galaxy NGC 1530Apr 26 1999We present 13CO(1-0) and 12CO(2-1) aperture synthesis maps of the barred spiral galaxy NGC1530. The angular resolutions are respectively 3''.1 and 1''.6. Both transitions show features similar to the 12CO(1-0) map, with a nuclear feature (a ring or unresolved ... More
Production of complex particles in low energy spallation and in fragmentation reactions by in-medium random clusterizationMay 18 2005Rules for in-medium complex particle production in nuclear reactions are proposed. These rules have been implemented in two models to simulate nucleon-nucleus and nucleus-nucleus reactions around the Fermi energy. Our work emphasizes the effect of randomness ... More
The far future of exoplanet direct characterizationOct 05 2009Oct 06 2009In this outlook we describe what could be the next steps of the direct characterization of habitable exoplanets after first the medium and large mission projects and investigate the benefits of the spectroscopic and direct imaging approaches. We show ... More
Combining angular differential imaging and accurate polarimetry with SPHERE/IRDIS to characterize young giant exoplanetsSep 21 2017Oct 16 2017Young giant exoplanets emit infrared radiation that can be linearly polarized up to several percent. This linear polarization can trace: 1) the presence of atmospheric cloud and haze layers, 2) spatial structure, e.g. cloud bands and rotational flattening, ... More
Neutrino oscillations along the Earth to probe flavor parameters: a NeuWorldJan 11 2013Mar 12 2013On 2010 MINOS experiment was showing an hint of possible different mass splitting and mixing angles for neutrinos and anti-neutrinos, suggesting a charge-parity-time (CPT) violation in the lepton sector; last year 2012 a second result from MINOS showed ... More
Beaming Selection and SN-GRB-Jets EvolutionFeb 19 2009After a decade of Fireball reign there is a hope for thin collimated Jet to solve the Supernova-GRB mystery
Anisotropies of Cosmic Rays and Search for Intergalactic Cascades from the direction of the Highest Energetic Cosmic Ray Events with the HEGRA Scintillator ArraySep 07 1999Data taken with the HEGRA Scintillator Array have been used to search for spatial anisotropies in the arrival directions of cosmic rays above 20 TeV. In this paper results on the search for TeV gamma-ray emission from the Galactic plane and the Gould ... More
Perturbative BPS-algebras in superstring theoryFeb 27 1997This paper investigates the algebraic structure that exists on perturbative BPS-states in the superstring, compactified on the product of a circle and a Calabi-Yau fourfold. This structure was defined in a recent article by Harvey and Moore. It shown ... More
Solid State Quantum BitsMay 27 2005We present the solid-state quantum circuits that have been developed in order to implement quantum bits suitable for a quantum processor. These qubits are either based on the quantum state of a single particle (semiconductor qubits), or on the quantum ... More
Applying MVC and PAC patterns in mobile applicationsJan 20 2010Additional requirements are set for mobile applications in relation to applications for desktop computers. These requirements primarily concern the support to different platforms on which such applications are performed, as well as the requirement for ... More
Bound States and Superconductivity in Dense Fermi SystemsDec 02 2008A quantum field theoretical approach to the thermodynamics of dense Fermi systems is developed for the description of the formation and dissolution of quantum condensates and bound states in dependence of temperature and density. As a model system we ... More
Gravity as an effective theoryOct 21 2009Using as inspiration the well known chiral effective lagrangian describing the interactions of pions at low energies, in these lectures we review the quantization procedure of Einstein gravity in the spirit of effective field theories. As has been emphasized ... More
Superconductivity in the 2D Hubbard model: Electron doping is differentAug 04 2008A variational Monte Carlo calculation is used for studying the ground state of the two-dimensional Hubbard model, including hopping between both nearest and next-nearest neighbor sites. Superconductivity with d-wave symmetry is found to be restricted ... More
Classical Functional Bethe Ansatz for $SL(N)$: separation of variables for the magnetic chainMar 04 1994The Functional Bethe Ansatz (FBA) proposed by Sklyanin is a method which gives separation variables for systems for which an $R$-matrix is known. Previously the FBA was only known for $SL(2)$ and $SL(3)$ (and associated) $R$-matrices. In this paper I ... More
A new class of magnetic materials: Sr2FeMoO6 and related compoundsFeb 27 2001Ordered double perovskite oxides of the general formula, A2BB'O6, have been known for several decades to have interesting electronic and magnetic properties. However, a recent report of a spectacular negative magnetoresistance effect in a specific member ... More
Existence, multiplicity and stability of endemic states for an age-structured S-I epidemic modelJun 20 2008Feb 25 2010We study an S--I type epidemic model in an age-structured population, with mortality due to the disease. A threshold quantity is found that controls the stability of the disease-free equilibrium and guarantees the existence of an endemic equilibrium. ... More
A locally symmetric Kaehler Einstein structure on the cotangent bundle of a space formAug 25 2003We obtain a locally symmetric Kaehler Einstein structure on the cotangent bundle of a Riemannian manifold of negative constant sectional curvature. Similar results are obtained on a tube around zero section in the cotangent bundle, in the case of a Riemannian ... More
Semi-classical description of the frustrated antiferromagnetic chainSep 21 1994The antiferromagnetic Heisenberg model on a chain with nearest and next nearest neighbor couplings is mapped onto the $SO(3)$ nonlinear sigma model in the continuum limit. In one spatial dimension this model is always in its disordered phase and a gap ... More
GSC 2314-0530: the shortest-period eclipsing system with dMe componentsMay 03 2010CCD photometric observations in VRI colors and spectroscopic observations of the newly discovered eclipsing binary GSC 2314-0530 (NSVS 6550671) with dMe components and very short period of P=0.192636 days are presented. The simultaneous light-curve solution ... More
Non-existence of a dilaton gravity action for the exact string black holeOct 07 2002Nov 07 2002We prove that no local diffeomorphism invariant two-dimensional theory of the metric and the dilaton without higher derivatives can describe the exact string black hole solution found a decade ago by Dijkgraaf, Verlinde and Verlinde. One of the key points ... More
eta and eta' mesons and dimension 2 gluon condensate <A^2>Dec 05 2005The study of light pseudoscalar quark-antiquark bound states in the Dyson-Schwinger approach with the effective QCD coupling enhanced by the interplay of the dimension 2 gluon condensate <A^2> and dimension 4 gluon condensate <F^2>, is extended to the ... More
Supersymmetric AdS(4) compactifications of IIA supergravityDec 21 2004Jan 25 2005We derive necessary and sufficient conditions for N=1 compactifications of (massive) IIA supergravity to AdS(4) in the language of SU(3) structures. We find new solutions characterized by constant dilaton and nonzero fluxes for all form fields. All fluxes ... More
A Selection of Giant Radio Sources from NVSSMar 22 2016May 10 2016Results of the application of pattern recognition techniques to the problem of identifying Giant Radio Sources (GRS) from the data in the NVSS catalog are presented and issues affecting the process are explored. Decision-tree pattern recognition software ... More
Comparing Pattern Recognition Feature Sets for Sorting Triples in the FIRST DatabaseMay 03 2006Pattern recognition techniques have been used with increasing success for coping with the tremendous amounts of data being generated by automated surveys. Usually this process involves construction of training sets, the typical examples of data with known ... More
Topological Dependence of Universal Correlations in Multi-Parameter HamiltoniansDec 03 1996Universality of correlation functions obtained in parametric random matrix theory is explored in a multi-parameter formalism, through the introduction of a diffusion matrix $D_{ij}(R)$, and compared to results from a multi-parameter chaotic model. We ... More
A class of locally symmetric Kaehler Einstein structures on the cotangent bundle of a space formJul 14 2004We obtain a class of locally symmetric Kaehler Einstein structures on the cotangent bundle of a Riemannian manifold of negative sectional curvature. Similar results are obtained in the case of a Riemannian manifold of positive sectional curvature. The ... More
EChO - Exoplanet Characterisation ObservatoryDec 12 2011A dedicated mission to investigate exoplanetary atmospheres represents a major milestone in our quest to understand our place in the universe by placing our Solar System in context and by addressing the suitability of planets for the presence of life. ... More
Chiral symmetry breaking via constituent quarks for qbarq pseudoscalar mesonsJul 18 2005We base our chiral symmetry approach on the quark-level linear sigma model Lagrangian. Then we review the Nambu--Goldstone theorem with vanishing pi, K, eta_8 masses. Next we dynamically generate the pi, K, eta_8 masses away from the chiral limit. Then ... More
Quantitative determination of the level of cooperation in the presence of punishment in three public good experimentsOct 25 2006Nov 21 2007Strong reciprocity is a fundamental human characteristic associated with our extraordinary sociality and cooperation. Laboratory experiments on social dilemma games and many field studies have quantified well-defined levels of cooperation and propensity ... More
Representations of algebraic groups over a 2-dimensional local fieldFeb 14 2003Jun 14 2004We introduce a categorical framework for the study of representations of $G_F$, where $G$ is a reductive group, and $\bF$ is a 2-dimensional local field, i.e. $F=K((t))$, where $K$ is a local field. Our main result says that the space of functions on ... More