Results for "K. H. Andersen"

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A Particle Model of Rolling Grain Ripples Under WavesSep 09 1999May 02 2000A simple model is presented for the formation of rolling grain ripples on a flat sand bed by the oscillatory flow generated by a surface wave. An equation of motion is derived for the individual ripples, seen as "particles", on the otherwise flat bed. ... More
Hierarchical Markovian modeling of multi-time scale systemsJan 15 2002Feb 26 2002We present a systematic way to analyze and model systems having many characteristic time-scales. The method we propose is employed for a test-case of a meandering jet model manifesting chaotic tracer dispersion with long time-correlations. We first choose ... More
Shell Model for Time-correlated Random Advection of Passive ScalarsFeb 09 1999Oct 20 1999We study a minimal shell model for the advection of a passive scalar by a Gaussian time correlated velocity field. The anomalous scaling properties of the white noise limit are studied analytically. The effect of the time correlations are investigated ... More
Bursts and Shocks in a Continuum Shell ModelMar 26 1998We study a "burst" event, i. e. the evolution of an initial condition having support only in a finite interval of k-space, in the continuum shell model due to Parisi. We show that the continuum equation without forcing or dissipation can be explicitly ... More
Ultrabright Linearly Polarized Photon Generation from a Nitrogen Vacancy Center in a Nanocube Dimer AntennaJun 29 2017We demonstrate an exceptionally bright photon source based on a single nitrogen- vacancy center (NV-center) in a nanodiamond (ND), placed in the nanoscale gap between two monocrystalline silver cubes in a dimer configuration. The system is operated near ... More
Gold Photoluminescence Wavelength and Polarization EngineeringSep 16 2016We demonstrate engineering of the spectral content and polarization of photoluminescence (PL) from arrayed gold nanoparticles atop a subwavelength-thin dielectric spacer and optically-thick gold film, a configuration that supports gap-surface plasmon ... More
UCN production by multiphonon processes in superfluid Helium under pressureNov 26 2008Jan 29 2009Cold neutrons are converted to ultra-cold neutrons (UCN) by the excitation of a single phonon or multiphonons in superfluid helium. The dynamic scattering function S(q, omega) of the superfluid helium strongly depends on pressure, leading to a pressure- ... More
Simple stochastic models showing strong anomalous diffusionApr 05 2000Sep 05 2000We show that {\it strong} anomalous diffusion, i.e. $\mean{|x(t)|^q} \sim t^{q \nu(q)}$ where $q \nu(q)$ is a nonlinear function of $q$, is a generic phenomenon within a class of generalized continuous-time random walks. For such class of systems it is ... More
Pulses in the Zero-Spacing Limit of the GOY ModelMay 12 1999Aug 31 1999We study the propagation of localised disturbances in a turbulent, but momentarily quiescent and unforced shell model (an approximation of the Navier-Stokes equations on a set of exponentially spaced momentum shells). These disturbances represent bursts ... More
Corridors of barchan dunes: stability and size selectionMar 06 2003Jul 31 2003Barchans are crescentic dunes propagating on a solid ground. They form dune fields in the shape of elongated corridors in which the size and spacing between dunes are rather well selected. We show that even very realistic models for solitary dunes do ... More
Study of FK Comae Berenices: VII. Correlating photospheric and chromospheric activityMay 26 2015We study the connection between the chromospheric and photospheric behaviour of the active late-type star FK Comae. We use spot temperature modelling, light curve inversion based on narrow- and wide-band photometric measurements, Halpha observations from ... More
IRAS 05358+3543: Multiple outflows at the earliest stages of massive star formationMar 01 2002We present a high-angular-resolution molecular line and millimeter continuum study of the massive star formation site IRAS 05358+3543. The most remarkable feature is a highly collimated (collimation factor ~10) and massive (>10 M_sun) bipolar outflow ... More
Self-Organized Topological Superconductivity in a Yu-Shiba-Rusinov ChainSep 24 2015Apr 22 2016We study a chain of magnetic moments exchange coupled to a conventional three dimensional superconductor. In the normal state the chain orders into a collinear configuration, while in the superconducting phase we find that ferromagnetism is unstable to ... More
A design study of VOR: a versatile optimal resolution chopper spectrometer for the ESSJul 02 2014VOR, the versatile optimal resolution chopper spectrometer, is designed to probe dynamic phenomena that are currently inaccessible for inelastic neutron scattering due to flux limitations. VOR is a short instrument by the standards of the European Spallation ... More
Surpassing the standard quantum limit for optical imaging using non-classical multimode lightApr 04 2002Using continuous wave superposition of spatial modes, we demonstrate experimentally displacement measurement of a light beam below the standard quantum limit. Multimode squeezed light is obtained by mixing a vacuum squeezed beam and a coherent beam that ... More
Pattern Dynamics of Vortex Ripples in Sand: Nonlinear Modeling and Experimental ValidationJan 29 2002Vortex ripples in sand are studied experimentally in a one-dimensional setup with periodic boundary conditions. The nonlinear evolution, far from the onset of instability, is analyzed in the framework of a simple model developed for homogeneous patterns. ... More
Spiral magnetic order and topological superconductivity in a chain of magnetic adatoms on a two-dimensional superconductorJul 27 2016Oct 19 2016We study the magnetic and electronic phases of a 1D magnetic adatom chain on a 2D superconductor. In particular, we confirm the existence of a `self-organized' 1D topologically non-trivial superconducting phase within the set of subgap Yu-Shiba-Rusinov ... More
The Overlapping Muffin-Tin ApproximationAug 01 2008Aug 03 2008We present the formalism and demonstrate the use of the overlapping muffin-tin approximation (OMTA). This fits a full potential to a superposition of spherically symmetric short-ranged potential wells plus a constant. For one-electron potentials of this ... More
Experimental investigation of the Landau-Pomeranchuk-Migdal effect in low-Z targetsSep 23 2013In the CERN NA63 collaboration we have addressed the question of the potential inadequacy of the commonly used Migdal formulation of the Landau-Pomeranchuk-Migdal (LPM) effect by measuring the photon emission by 20 and 178 GeV electrons in the range 100 ... More
Model for the low-temperature magnetic phases observed in doped YBa_2Cu_3O_{6+x}Mar 18 1997A classical statistical model for the antiferromagnetic (AFM) ordering of the Cu-spins in the CuO_2 planes of reduced YBa_2Cu_3O_{6+x} type materials is presented. The magnetic phases considered are the experimentally observed high-temperature AFI phase ... More
Disentangling time-focusing from beam divergence: a novel approach for high-flux thermal neutron spectroscopy at continuous and long-pulse sourcesApr 12 2019We present the concept of a novel time-focusing technique for neutron spectrometers, which allows to disentangle time-focusing from beam divergence. The core of this approach is a double rotating-crystal monochromator that can be used to extract a larger ... More
Interpolation across a muffin-tin interstitial using localized linear combinations of spherical wavesApr 27 2016Jul 22 2016A method for 3D interpolation between hard spheres is described. The function to be interpolated could be the charge density between atoms in condensed matter. Its electrostatic potential is found analytically, and so are various integrals. Periodicity ... More
Mesoscopic and Microscopic Phase Segregation in Manganese PerovskitesJun 12 2000Jun 16 2000Mesoscopic (500-2000 Angstrom) and microscopic (5-20 Angstrom) phase segregation with temperature and magnetic field was studied in the model manganite Pr0.7Ca0.3MnO3 by high-resolution neutron diffraction and inelastic neutron scattering. Intra-granular ... More
The Stability Balloon for Two-dimensional Vortex Ripple PatternsJun 22 2001Patterns of vortex ripples form when a sand bed is subjected to an oscillatory fluid flow. Here we describe experiments on the response of regular vortex ripple patterns to sudden changes of the driving amplitude a or frequency f. A sufficient decrease ... More
Temperature Dependence of the Flux Line Lattice Transition into Square Symmetry in Superconducting LuNi$_2$B$_2$CApr 03 2001We have investigated the temperature dependence of the H || c flux line lattice structural phase transition from square to hexagonal symmetry, in the tetragonal superconductor LuNi_2B_2C (T_c = 16.6 K). At temperatures below 10 K the transition onset ... More
Multiband model for tunneling in MgB2 junctionsNov 07 2001May 13 2002A theoretical model for quasiparticle and Josephson tunneling in multiband superconductors is developed and applied to MgB2-based junctions. The gap functions in different bands in MgB2 are obtained from an extended Eliashberg formalism, using the results ... More
High energy cosmic-ray interactions with particles from the SunMar 25 2011Cosmic-ray protons with energies above $10^{16}$ eV passing near the Sun may interact with photons emitted by the Sun and be excited to a $\Delta^+$ resonance. When the $\Delta^+$ decays, it produces pions which further decay to muons and photons which ... More
Interdependence of magnetism and superconductivity in the borocarbide TmNi2B2CDec 16 1999We have discovered a new antiferromagnetic phase in TmNi2B2C by neutron diffraction. The ordering vector is Q_A = (0.48,0,0) and the phase appears above a critical in-plane magnetic field of 0.9 T. The field was applied in order to test the assumption ... More
GRB 000301C: a possible short/intermediate duration burst connected to a DLA systemSep 03 2001We discuss two main aspects of the GRB 000301C afterglow (Fynbo et al. 2000, Jensen et al. 2000); its short duration and its possible connection with a Damped Ly-alpha Absorber (DLA). GRB 000301C falls in the short class of bursts, though it is consistent ... More
Band structure and atomic sum rules for x-ray dichroismJul 06 2000Corrections to the atomic orbital sum rule for circular magnetic x-ray dichroism in solids are derived using orthonormal LMTOs as a single-particle basis for electron band states.
NMTO Wannier-like functions for insulators and metalsApr 14 2005Apr 18 2005Within this paper we outline a method able to generate truly minimal basis sets which describe either a group of bands, a band, or even just the occupied part of a band accurately. These basis sets are the so-called NMTOs, Muffin Tin Orbitals of order ... More
The Steenrod problem of realizing polynomial cohomology ringsApr 30 2007Aug 04 2008In this paper we completely classify which graded polynomial R-algebras in finitely many even degree variables can occur as the singular cohomology of a space with coefficients in R, a 1960 question of N. E. Steenrod, for a commutative ring R satisfying ... More
Efficient collisional blockade loading of single atom into a tight microtrapJun 05 2015We show that controlled inelastic collisions can improve the single atom loading efficiency in the collisional blockade regime of optical microtraps. A collisional loss process where only one of the colliding atoms are lost, implemented during loading, ... More
Three-dimensional MgB$_{2}$-type superconductivity in hole-doped diamondApr 19 2004Nov 30 2004We substantiate by calculations that the recently discovered superconductivity below 4 K in 3% boron-doped diamond is caused by electron-phonon coupling of the same type as in MgB$_2$, albeit in 3 dimensions. Holes at the top of the zone-centered, degenerate ... More
Magnitude and phase reciprocity calibration of ultrasonic piezoelectric disk in airApr 08 2016A modified conventional three-transducer reciprocity calibration method is used to measure the magnitude and phase responses of the transmitting voltage response and the free-field open-circuit receiving voltage sensitivity of ultrasonic piezoelectric ... More
The classification of 2-compact groupsNov 14 2006Jan 11 2007We prove that any connected 2-compact group is classified by its 2-adic root datum, and in particular the exotic 2-compact group DI(4), constructed by Dwyer-Wilkerson, is the only simple 2-compact group not arising as the 2-completion of a compact connected ... More
The classification of 2-compact groups (talk summary)Oct 10 2005This is a summary of a talk given at the "Conference on Pure and Applied Topology", Isle of Skye, June 24, 2005. It contains an announcement and sketch of proof of the classification of 2-compact groups.
Automorphisms of p-compact groups and their root dataOct 10 2005Jan 11 2007We construct a model for the space of automorphisms of a connected p-compact group in terms of the space of automorphisms of its maximal torus normalizer and its root datum. As a consequence we show that any homomorphism to the outer automorphism group ... More
Muffin Tin Orbitals of Arbitrary OrderOct 27 2000Oct 30 2000We have derived orbital basis sets from scattering theory. They are expressed as polynomial approximations to the energy dependence of a set of partial waves, in quantized form. The corresponding matrices, as well as the Hamiltonian and overlap matrices, ... More
Bose-Einstein Condensation in Anisotropic Harmonic TrapsNov 08 1996We study the thermodynamic behaviour of an ideal gas of bosons trapped in a three-dimensional anisotropic harmonic oscillator potential. The condensate fraction as well as the specific heat is calculated using the Euler-Maclaurin approximation. For a ... More
Exchange cotunneling through quantum dots with spin-orbit couplingJun 11 2010We investigate the effects of spin-orbit interaction (SOI) on the exchange cotunneling through a spinful Coulomb blockaded quantum dot. In the case of zero magnetic field, Kondo effect is shown to take place via a Kramers doublet and the SOI will merely ... More
The C*-algebra of an affine map on the 3-torusApr 01 2012We study the C*-algebra of an affine map on a compact abelian group and give necessary and sufficient conditions for strong transitivity when the group is a torus. The structure of the C*-algebra is completely determined for all strongly transitive affine ... More
Superconductivity-enhanced bias spectroscopy in carbon nanotube quantum dotsSep 11 2008May 25 2009We study low-temperature transport through carbon nanotube quantum dots in the Coulomb blockade regime coupled to niobium-based superconducting leads. We observe pronounced conductance peaks at finite source-drain bias, which we ascribe to elastic and ... More
Imaging the impact on cuprate superconductivity of varying the inter-atomic distances within individual crystal unit-cellsSep 03 2008Many theoretical models of high temperature superconductivity focus only on the doping dependence of the CuO2 plane electronic structure. But such models are manifestly insufficient to explain the strong variations in superconducting critical temperature ... More
The jet and circumburst stellar wind of GRB 980519Jul 21 2000We present extensive multi-colour (UBVR_CI_C) photometry of the optical afterglow of GRB 980519. Upon discovery, 8.3 hours after the burst, the source was decaying as a power law, (t-t_GRB)^alpha, with a rapid decay rate alpha_1 = - 1.73+-0.04. About ... More
Kondo-Enhanced Andreev Tunneling in InAs Nanowire Quantum DotsMar 10 2007We report measurements of the nonlinear conductance of InAs nanowire quantum dots coupled to superconducting leads. We observe a clear alternation between odd and even occupation of the dot, with sub-gap-peaks at $|V_{sd}|=\Delta/e$ markedly stronger(weaker) ... More
Constraints on the optical afterglow emission of the short/hard burst GRB 010119Sep 29 2001We report optical observations of the short/hard burst GRB 010119 error box, one of the smallest error boxes reported to date for short/hard GRBs. Limits of R > 22.3 and I > 21.2 are imposed by observations carried out 20.31 and 20.58 hours after the ... More
Experimental investigations of synchrotron radiation at the onset of the quantum regimeJun 28 2012The classical description of synchrotron radiation fails at large Lorentz factors, $\gamma$, for relativistic electrons crossing strong transverse magnetic fields $B$. In the rest frame of the electron this field is comparable to the so-called critical ... More
Staging superstructures in high-$T_c$ Sr/O co-doped La$_{2-x}$Sr$_x$CuO$_{4+y}$Jul 12 2017Aug 11 2017We present high energy X-ray diffraction studies on the structural phases of an optimal high-$T_c$ superconductor La$_{2-x}$Sr$_x$CuO$_{4+y}$ tailored by co-hole-doping. This is specifically done by varying the content of two very different chemical species, ... More
Ultracold-neutron infrastructure for the gravitational spectrometer GRANITNov 11 2008Jan 29 2009The gravitational spectrometer GRANIT will be set up at the Institut Laue Langevin. It will profit from the high ultracold neutron density produced by a dedicated source. A monochromator made of crystals from graphite intercalated with potassium will ... More
Magnetic ordering in electronically phase separated Sr/O co-doped La(2-x)Sr(x)CuO(4+y)Apr 01 2009Jun 10 2009We present results of magnetic neutron diffraction experiments on the co-doped super-oxygenated La(2-x)Sr(x)CuO(4+y) (LSCO+O) system with x=0.09. The spin-density wave has been studied and we find long-range incommensurate antiferromagnetic order below ... More
Cellularity of certain quantum endomorphism algebrasMar 05 2013We exhibit for all positive integers r, an explicit cellular structure for the endomorphism algebra of the r'th tensor power of an integral form of the Weyl module with highest weight d of the quantised enveloping algebra of sl2. When q is specialised ... More
Compensated electron and hole pockets in an underdoped high Tc superconductorJan 27 2010Apr 28 2010We report quantum oscillations in the underdoped high Tc YBCO over a wide range in magnetic field 28<B<85 T corresponding to ~12 oscillations, enabling the Fermi surface topology to be mapped to high resolution. As earlier reported by Sebastian et al., ... More
Phonon Mode Spectroscopy, Electron-Phonon Coupling and the Metal-Insulator Transition in Quasi-One-Dimensional M2Mo6Se6Jul 30 2010We present electronic structure calculations, electrical resistivity data and the first specific heat measurements in the normal and superconducting states of quasi-one-dimensional M2Mo6Se6 (M = Tl, In, Rb). Rb2Mo6Se6 undergoes a metal-insulator transition ... More
Hybrid Plasmonic Bullseye Antennas for Efficient Photon CollectionApr 12 2018We propose highly efficient hybrid plasmonic bullseye antennas for collecting photon emission from nm-sized quantum emitters. In our approach, the emitter radiation is coupled to surface plasmon polaritons that are consequently converted into highly directional ... More
Excitation of surface plasmon polariton modes with multiple nitrogen vacancy centers in single nanodiamondsSep 15 2016Nitrogen-vacancy (NV) centers in diamonds are interesting due to their remarkable characteristics that are well suited to applications in quantum-information processing and magnetic field sensing, as well as representing stable fluorescent sources. Multiple ... More
Diffraction of slow neutrons by holographic SiO_2 nanoparticle-polymer composite gratingsJun 07 2011Diffraction experiments with holographic gratings recorded in SiO$_2$ nanoparticle-polymer composites have been carried out with slow neutrons. The influence of parameters such as nanoparticle concentration, grating thickness and grating spacing on the ... More
Phonon-induced quadrupolar ordering of the magnetic superconductor TmNi$_2$B$_2$CAug 26 2005We present synchrotron x-ray diffraction studies revealing that the lattice of thulium borocarbide is distorted below T_Q = 13.5 K at zero field. T_Q increases and the amplitude of the displacements is drastically enhanced, by a factor of 10 at 60 kOe, ... More
Kinetic hindrance during the initial oxidation of Pd(100) at ambient pressuresNov 24 2003The oxidation of the Pd(100) surface at oxygen pressures in the 10^-6 to 10^3 mbar range and temperatures up to 1000 K has been studied in-situ by surface x-ray diffraction (SXRD). The results provide direct structural information on the phases present ... More
Polarized 3He as a probe for short-range spin-dependent interactionsSep 17 2010Oct 19 2010We have studied the relaxation of a spin-polarized gas in a magnetic field, in the presence of short-range spin-dependent interactions. As a main result we have established a link between the specific properties of the interaction and the dependence of ... More
The Einstein-Podolsky-Rosen paradox: from concepts to applicationsMay 31 2008Dec 19 2008This Colloquium examines the field of the EPR Gedankenexperiment, from the original paper of Einstein, Podolsky and Rosen, through to modern theoretical proposals of how to realize both the continuous-variable and discrete versions of the EPR paradox. ... More
s-wave superconductivity from antiferromagnetic spin-fluctuation model for bilayer materialsJan 25 1995It is usually believed that the spin-fluctuation mechanism for high-temperature superconductivity results in d-wave pairing, and that it is destructive for the conventional phonon-mediated pairing. We show that in bilayer materials, due to nearly perfect ... More
Reduced fusion systems over 2-groups of small orderJun 16 2016We prove, when $S$ is a $2$-group of order at most $2^9$, that each reduced fusion system over $S$ is the fusion system of a finite simple group and is tame. It then follows that each saturated fusion system over a $2$-group of order at most $2^9$ is ... More
Directed Reduction Algorithms and Decomposable GraphsMar 27 2013In recent years, there have been intense research efforts to develop efficient methods for probabilistic inference in probabilistic influence diagrams or belief networks. Many people have concluded that the best methods are those based on undirected graph ... More
Random matrix theory for systems with an approximate symmetry and widths of acoustic resonances in thin chaotic platesNov 30 2000We discuss a random matrix model of systems with an approximate symmetry and present the spectral fluctuation statistics and eigenvector characteristics for the model. An acoustic resonator like, e.g., an aluminium plate may have an approximate symmetry. ... More
Third-generation muffin-tin orbitalsMar 05 2002By the example of sp^3-bonded semiconductors, we illustrate what 3rd-generation muffin-tin orbitals (MTOs) are. We demonstrate that they can be downfolded to smaller and smaller basis sets: sp^3d^10,sp^3, and bond orbitals. For isolated bands, it is possible ... More
Nonequilibrium transport via spin-induced sub-gap states in superconductor/quantum dot/normal metal cotunnel junctionsJul 27 2010Nov 12 2010We study low-temperature transport through a Coulomb blockaded quantum dot (QD) contacted by a normal (N), and a superconducting (S) electrode. Within an effective cotunneling model the conduction electron self energy is calculated to leading order in ... More
Quantum confinement in CdSe nanocrystallitesOct 07 2001Quantum confinement increases the spacing between energy levels as the nanocrystallite size is decreased. Its qualitative features hold both for states localized near the center of a nanocrystallite and those near the surface, such as states due primarily ... More
How chemistry controls electron localization in 3d1 perovskites: A Wannier-function studyApr 01 2005Oct 11 2005In the series of 3d1 t2g perovskites, SrVO3--CaVO3--LaTiO3--YTiO3 the transition-metal d electron becomes increasingly localized and undergoes a Mott transition between CaVO3 and LaTiO3. By defining a low-energy Hubbard Hamiltonian in the basis of Wannier ... More
The recurrence time of Dansgaard-Oeschger events and limits on the possible periodic componentMay 12 2005By comparing the high-resolution isotopic records from the GRIP and NGRIP icecores, we approximately separate the climate signal from local noise to obtain an objective criterion for defining Dansgaard-Oeschger events. Our analysis identifies several ... More
Signatures of orbital loop currents in the spatially resolved local density of statesMar 06 2012Polarized neutron scattering measurements have suggested that intra-unit cell antiferromagnetism may be associated with the pseudogap phase. Assuming that loop current order is responsible for the observed magnetism, we calculate some signatures of such ... More
The SONG prototype: Efficiency of a robotic telescopeJan 24 2019The Stellar Observations Network Group prototype telescope at the Teide Observatory has been operating in scientific mode since March 2014. The first year of observations has entirely been carried out using the high resolution echelle spectrograph. Several ... More
Nanodiamond dust and the energy distribution of quasarsSep 24 2005The spectral energy distribution of quasars shows a sharp steepening of the continuum shortward of ~ 1100 A. The steepening could be a result of dust absorption. We present a dust extinction model which considers crystalline carbon grains and compare ... More
Species competition: coexistence, exclusion and clusteringDec 06 2008Jul 22 2009We present properties of Lotka-Volterra equations describing ecological competition among a large number of competing species. First we extend to the case of a non-homogeneous niche space stability conditions for solutions representing species coexistence. ... More
Unravelling incommensurate magnetism and its emergence in iron-based superconductorsDec 22 2016Nov 09 2018We focus on a broad class of tetragonal itinerant systems sharing a tendency towards the spontaneous formation of incommensurate magnetism with ordering wavevectors $\mathbf{Q}_{1,2}=(\pi-\delta,0)/(0,\pi-\delta)$ or $\mathbf{Q}_{1,2}=(\pi,\delta)/(-\delta,\pi)$. ... More
Theoretical study of impurity-induced magnetism in FeSeNov 05 2018Experimental evidence suggests that FeSe is close to a magnetic instability, and recent scanning tunneling microscopy (STM) measurements on FeSe multilayer films have revealed stripe order locally pinned near defect sites. Motivated by these findings, ... More
Orbital fluctuations in the different phases of LaVO3 and YVO3Feb 13 2007Aug 31 2007We investigate the importance of quantum orbital fluctuations in the orthorhombic and monoclinic phases of the Mott insulators LaVO3 and YVO3. First, we construct ab-initio material-specific t2g Hubbard models. Then, by using dynamical mean-field theory, ... More
Model Hamiltonian parameters for half-metallic ferromagnets NiMnSb and CrO2Mar 10 2006Jul 23 2006Using the recently developed Nth-order muffin-tin-orbital (NMTO) based downfolding technique we revisit the electronic properties of half-metallic ferromagnets, the semi-Heusler NiMnSb and rutile CrO2. The NMTO Wannier orbitals for the Mn-d and Cr-t2g ... More
Electron-phonon interaction in Graphite Intercalation CompoundsJan 15 2007Motivated by the recent discovery of superconductivity in Ca- and Yb-intercalated graphite (CaC$_{6}$ and YbC$_{6}$) and from the ongoing debate on the nature and role of the interlayer state in this class of compounds, in this work we critically study ... More
Reduced, tame and exotic fusion systemsSep 03 2010We define here two new classes of saturated fusion systems, reduced fusion systems and tame fusion systems. These are motivated by our attempts to better understand and search for exotic fusion systems: fusion systems which are not the fusion systems ... More
Reduced fusion systems over 2-groups of small orderJun 16 2016May 31 2017We prove, when $S$ is a $2$-group of order at most $2^9$, that each reduced fusion system over $S$ is the fusion system of a finite simple group and is tame. It then follows that each saturated fusion system over a $2$-group of order at most $2^9$ is ... More
Buckling and d-Wave Pairing in HiTc-SuperconductorsOct 24 1997We have investigated whether the electron-phonon interaction can support a d-wave gap-anisotropy. On the basis of models derived from LDA calculations, as well as LDA linear-response calculations we argue that this is the case, for materials with buckled ... More
Conditions for abrupt failure in the democratic fiber bundle modelDec 29 1997We argue that the existence of abrupt failure in the democratic fiber bundle model is more general than concluded by da Silveira in his comment (cond-mat/9709327). We refute his claim that the nature of the rupture process in the DFBM depends on the ``disorder ... More
Effects of Grain Morphology and Impurities on the Infrared Spectra of Silicon Carbide ParticlesNov 15 2001Nov 21 2001In this paper we demonstrate that distinguishing between the polytypes of silicon carbide by means of infrared features in small-grain spectra is impossible. Therefore, the infrared spectra of carbon stars, unfortunately, do not provide a means for drawing ... More
Food web framework for size-structured populationsApr 23 2010Dec 06 2010We synthesise traditional unstructured food webs, allometric body size scaling, trait-based modelling, and physiologically structured modelling to provide a novel and ecologically relevant tool for size-structured food webs. The framework allows food ... More
Passive scalar intermittency in low temperature helium flowsJul 11 2000We report new measurements of turbulent mixing of temperature fluctuations in a low temperature helium gas experiment, spanning a range of microscale Reynolds number, $R_{\lambda}$, from 100 to 650. The exponents $\xi_{n}$ of the temperature structure ... More
The SONG project and the prototype node at TenerifeNov 08 2011SONG (Stellar Observations Network Group) is a global network of 1-m class robotic telescopes that is under development. The SONG prototype will shortly be operational at Observatorio del Teide, Tenerife, and first light is expected by December 2011. ... More
Nonequilibrium transport through a spinful quantum dot with superconducting leadsSep 07 2011We study the nonlinear cotunneling current through a spinful quantum dot contacted by two superconducting leads. Applying a general nonequilibrium Green function formalism to an effective Kondo model, we study the rich variation in the IV-characteristics ... More
LDA energy bands, low-energy Hamiltonians, t', t'', t_{perp}(k), and J_{perp}Sep 08 1995We describe the LDA bandstructure of YBa_2Cu_3O_7 in the 2 eV range from the Fermi energy using orbital projections and compare with YBa_2Cu_4O_8. Then, the high-energy and chain-related degrees of freedom are integrated out and we arrive at two, nearest-neighbor, ... More
Multiplet ligand-field theory using Wannier orbitalsNov 21 2011Mar 07 2012We demonstrate how ab initio cluster calculations including the full Coulomb vertex can be done in the basis of the localized, generalized Wannier orbitals which describe the low-energy density functional (LDA) band structure of the infinite crystal, ... More
Self-consistent theory of phonon renormalization and electron-phonon coupling near a 2D Kohn singularityOct 02 2007We show that the usual expression for evaluating electron-phonon coupling and the phonon linewidth in 2D metals with a cylindrical Fermi surface cannot be applied near the wave vector corresponding to the Kohn singularity. Instead, the Dyson equation ... More
Electron-phonon interaction in the normal and superconducting states of MgB2Feb 27 2001Apr 18 2001For the 40K-superconductor MgB2 we have calculated the electronic and phononic structures and the electron-phonon interaction throughout the Brillouin zone ab initio. In contrast to the isoelectronic graphite, MgB2 has holes in the bonding sigma-bands, ... More
Global Conditioning for Probabilistic Inference in Belief NetworksFeb 27 2013In this paper we propose a new approach to probabilistic inference on belief networks, global conditioning, which is a simple generalization of Pearl's (1986b) method of loopcutset conditioning. We show that global conditioning, as well as loop-cutset ... More
Tri-critical behavior in rupture induced by disorderSep 02 1996We discover a qualitatively new behavior for systems where the load transfer has limiting stress amplification as in real fiber composites. We find that the disorder is a relevant field leading to tri--criticality, separating a first-order regime where ... More
Phase fluctuations in atomic Bose gasesSep 07 2001Jan 24 2002We improve on the Popov theory for partially Bose-Einstein condensed atomic gases by treating the phase fluctuations exactly. As a result, the theory becomes valid in arbitrary dimensions and is able to describe the low-temperature crossover between three, ... More
Rigidity and Normal Modes in Random Matrix SpectraDec 15 1998We consider the Gaussian ensembles of random matrices and describe the normal modes of the eigenvalue spectrum, i.e., the correlated fluctuations of eigenvalues about their most probable values. The associated normal mode spectrum is linear, and for large ... More
Anomalous spin-waves and the commensurate-incommensurate magnetic phase transition in LiNiPO4Feb 13 2009Detailed spin-wave spectra of magneto-electric LiNiPO4 have been measured by neutron scattering at low temperatures in the commensurate (C) antiferromagnetic (AF) phase with ordering temperature 20.8 K. An anomalous low-energy mode is observed at the ... More
Direct proof of unique magnetic and superconducting phases in superoxygenated high-Tc cupratesJun 10 2013Jul 17 2013We present a combined magnetic neutron scattering and muon spin rotation study of the nature of the magnetic and superconducting phases in electronically phase separated La(2-x)Sr(x)CuO(4+y), x = 0.04, 065, 0.09. For all samples, we find long-range modulated ... More
The supernova 2003lw associated with X-ray flash 031203Mar 18 2004Apr 04 2004The X-Ray Flash (XRF), 031203 with a host galaxy at z=0.1055, is, apart from GRB980425, the closest Gamma-Ray Burst (GRB) or XRF known to date. We monitored its host galaxy from 1-100 days after the burst. In spite of the high extinction to the source ... More
Field-induced magnetic phases and electric polarization in LiNiPO4Jan 15 2009Neutron diffraction is used to probe the (H,T) phase diagram of magneto-electric (ME) LiNiPO4 for magnetic fields along the c-axis. At zero field the Ni spins order in two antiferromagnetic phases. One has commensurate (C) structures and general ordering ... More