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Current Sheets and Collisionless Damping in Kinetic Plasma TurbulenceApr 10 2013Jun 07 2013We present the first study of the formation and dissipation of current sheets at electron scales in a wave-driven, weakly collisional, 3D kinetic turbulence simulation. We investigate the relative importance of dissipation associated with collisionless ... More

Evidence of Critical Balance in Kinetic Alfven Wave Turbulence SimulationsDec 30 2011A numerical simulation of kinetic plasma turbulence is performed to assess the applicability of critical balance to kinetic, dissipation scale turbulence. The analysis is performed in the frequency domain to obviate complications inherent in performing ... More

Validity of the Taylor Hypothesis for Linear Kinetic Waves in the Weakly Collisional Solar WindMay 21 2014The interpretation of single-point spacecraft measurements of solar wind turbulence is complicated by the fact that the measurements are made in a frame of reference in relative motion with respect to the turbulent plasma. The Taylor hypothesis---that ... More

Temperature-dependent Saturation of Weibel-type Instabilities in Counter-streaming PlasmasFeb 22 2019We present the first 2X2V continuum Vlasov-Maxwell simulations of interpenetrating, unmagnetized plasmas to study the competition between two-stream, Oblique, and filamentation modes in the weakly relativistic regime. We find that after nonlinear saturation ... More

A Weakened Cascade Model for Turbulence in Astrophysical PlasmasSep 19 2011A refined cascade model for kinetic turbulence in weakly collisional astrophysical plasmas is presented that includes both the transition between weak and strong turbulence and the effect of nonlocal interactions on the nonlinear transfer of energy. The ... More

Interpreting Magnetic Variance Anisotropy Measurements in the Solar WindMay 03 2012The magnetic variance anisotropy ($\mathcal{A}_m$) of the solar wind has been used widely as a method to identify the nature of solar wind turbulent fluctuations; however, a thorough discussion of the meaning and interpretation of the $\mathcal{A}_m$ ... More

An extended MHD study of the 16 October 2015 MMS diffusion region crossingMar 15 2019The Magnetospheric Multiscale (MMS) mission has given us unprecedented access to high cadence particle and field data of magnetic reconnection at Earth's magnetopause. MMS first passed very near an X-line on 16 October 2015, the Burch event, and has since ... More

Multiscale nature of the dissipation range in gyrokinetic simulations of Alfvénic turbulenceMay 08 2015Jul 09 2015Nonlinear energy transfer and dissipation in Alfv\'en wave turbulence are analyzed in the first gyrokinetic simulation spanning all scales from the tail of the MHD range to the electron gyroradius scale. For typical solar wind parameters at 1 AU, about ... More

Physical Interpretation of the Angle Dependent Magnetic Helicity Spectrum in the Solar Wind: The Nature of Turbulent Fluctuations near the Proton Gyroradius ScaleMar 10 2014Motivated by recent observations of distinct parallel and perpendicular signatures in magnetic helicity measurements segregated by wave period and angle between the local magnetic field and the solar wind velocity, this paper undertakes a comparison of ... More

Collisionless Reconnection in the Large Guide Field Regime: Gyrokinetic Versus Particle-in-Cell SimulationsDec 18 2013Feb 18 2014Results of the first validation of large guide field, $B_g / \delta B_0 \gg 1$, gyrokinetic simulations of magnetic reconnection at a fusion and solar corona relevant $\beta_i = 0.01$ and solar wind relevant $\beta_i = 1$ are presented, where $\delta ... More

An Oscillating Langevin Antenna for Driving Plasma Turbulence SimulationsMay 09 2013Oct 21 2013A unique method of driving Alfvenic turbulence via an oscillating Langevin antenna is presented. This method of driving is motivated by a desire to inject energy into a finite domain numerical simulation in a manner that models the nonlinear transfer ... More

Using Synthetic Spacecraft Data to Interpret Compressible Fluctuations in Solar Wind TurbulenceJun 28 2012Kinetic plasma theory is used to generate synthetic spacecraft data to analyze and interpret the compressible fluctuations in the inertial range of solar wind turbulence. The kinetic counterparts of the three familiar linear MHD wave modes---the fast, ... More

The slow-mode nature of compressible wave power in solar wind turbulenceJun 21 2011We use a large, statistical set of measurements from the Wind spacecraft at 1 AU, and supporting synthetic spacecraft data based on kinetic plasma theory, to show that the compressible component of inertial range solar wind turbulence is primarily in ... More

The Quasilinear Premise for the Modeling of Plasma TurbulenceApr 10 2014The quasilinear premise is a hypothesis for the modeling of plasma turbulence in which the turbulent fluctuations are represented by a superposition of randomly-phased linear wave modes, and energy is transferred among these wave modes via nonlinear interactions. ... More

Effect of a weak ion collisionality on the dynamics of kinetic electrostatic shocksOct 04 2018Feb 06 2019In strictly collisionless electrostatic shocks, the ion distribution function can develop discontinuities along phase-space separatrices, due to partial reflection of the ion population. In this paper, we depart from the strictly collisionless regime ... More

Transition from ion-coupled to electron-only reconnection: Basic physics and implications for plasma turbulenceJan 28 2019Using kinetic particle-in-cell (PIC) simulations, we simulate reconnection conditions appropriate for the magnetosheath and solar wind, i.e., plasma beta (ratio of gas pressure to magnetic pressure) greater than 1 and low magnetic shear (strong guide ... More

Dissipation via Landau Damping in Two- and Three-Dimensional Plasma TurbulenceOct 09 2015Plasma turbulence is ubiquitous in space and astrophysical plasmas, playing an important role in plasma energization, but the physical mechanisms that lead to dissipation of the turbulent energy remain to be definitively identified. This work addresses ... More

Low Mach-number collisionless electrostatic shocks and associated ion accelerationSep 01 2017Dec 19 2017The existence and properties of low Mach-number ($M \gtrsim 1$) electrostatic collisionless shocks are investigated with a semi-analytical solution for the shock structure. We show that the properties of the shock obtained in the semi-analytical model ... More

[Plasma 2020 Decadal] Multipoint Measurements of the Solar Wind: A Proposed Advance for Studying Magnetized TurbulenceMar 13 2019A multi-institutional, multi-national science team will soon submit a NASA proposal to build a constellation of spacecraft to fly into the near-Earth solar wind in a swarm spanning a multitude of scales in order to obtain critically needed measurements ... More

Gyrokinetic Simulations of Solar Wind Turbulence from Ion to Electron ScalesApr 05 2011The first three-dimensional, nonlinear gyrokinetic simulation of plasma turbulence resolving scales from the ion to electron gyroradius with a realistic mass ratio is presented, where all damping is provided by resolved physical mechanisms. The resulting ... More

[Plasma 2020 Decadal] Disentangling the Spatiotemporal Structure of Turbulence Using Multi-Spacecraft DataMar 13 2019This white paper submitted for 2020 Decadal Assessment of Plasma Science concerns the importance of multi-spacecraft missions to address fundamental questions concerning plasma turbulence. Plasma turbulence is ubiquitous in the universe, and it is responsible ... More

The Violation of the Taylor Hypothesis in Measurements of Solar Wind TurbulenceJun 20 2014Motivated by the upcoming Solar Orbiter and Solar Probe Plus missions, qualitative and quantitative predictions are made for the effects of the violation of the Taylor hypothesis on the magnetic energy frequency spectrum measured in the near-Sun environment. ... More

Rational streams coalgebraicallyJul 25 2008Sep 19 2008We study rational streams (over a field) from a coalgebraic perspective. Exploiting the finality of the set of streams, we present an elementary and uniform proof of the equivalence of four notions of representability of rational streams: by finite dimensional ... More

Mobile Phone Faraday CageDec 23 2011A Faraday cage is an interesting physics phenomena where an electromagnetic wave can be excluded from a volume of space by enclosure with an electrically conducting material. The practical application of this in the classroom is to block the signal to ... More

The Wonders of LevitationOct 27 2010I discuss some interesting classroom demonstrations of diamagnetism and how this effect can produce levitation. The possibilities for hands-on demonstrations of diamagnetic and superconducting levitation are discussed. To conclude I discuss some practical ... More

Visualising a FuseOct 27 2010Nov 09 2010In this brief article I describe an experiment to illustrate how a fuse works. I have used this as part of lessons for my year 11 classes to demonstrate how an electrical fuse 'blows' when too high a current passes through it.

Trapped surfaces, horizons and exact solutions in higher dimensionsMar 30 2002May 18 2002A very simple criterion to ascertain if (D-2)-surfaces are trapped in arbitrary D-dimensional Lorentzian manifolds is given. The result is purely geometric, independent of the particular gravitational theory, of any field equations or of any other conditions. ... More

Applications of Super-Energy TensorsDec 13 1999In this contribution I intend to give a summary of the new relevant results obtained by using the general superenergy tensors. After a quick review of the definition and properties of these tensors, several of their mathematical and physical applications ... More

Super-energy tensorsJun 21 1999A purely algebraic construction of super-energy tensors for arbitrary fields is presented in any dimensions. These tensors have good mathematical and physical properties, and they can be used in any theory having as basic arena an n-dimensional manifold ... More

(Super)^n-Energy for arbitrary fields and its interchange: Conserved quantitiesMay 17 1999Inspired by classical work of Bel and Robinson, a natural purely algebraic construction of super-energy tensors for arbitrary fields is presented, having good mathematical and physical properties. Remarkably, there appear quantities with mathematical ... More

Remarks on Superenergy TensorsJan 07 1999We define super-energy tensors for arbitrary physical fields, including the gravitational, electromagnetic and massless scalar fields. We also define super-super-energy tensors, and so on. All these tensors satisfy the so-called "Dominant Superenergy ... More

Superenergy tensors and their applicationsFeb 20 2002In Lorentzian manifolds of any dimension the concept of causal tensors is introduced. Causal tensors have positivity properties analogous to the so-called ``dominant energy condition''. Further, it is shown how to build, from ANY given tensor $A$, a new ... More

Effective Operators and Extended SymmetryJul 30 1993In this note we expand on our previous study of the implications of LEP1 results for future colliders. We extend the effective operator-based analysis of De R\'ujula et al. to a larger symmetry group, and show at which cost their expectations can be relaxed. ... More

Gravitational waves from the collapse and bounce of a stellar core in tensor-scalar gravityNov 16 1999Tensor-scalar theory of gravity allows the generation of gravitational waves from astrophysical sources, like Supernov\ae{}, even in the spherical case. That motivated us to study the collapse of a degenerate stellar core, within tensor-scalar gravity, ... More

The Domino EffectJan 07 2004The physics of a row of toppling dominoes is discussed. In particular the forces between the falling dominoes are analyzed and with this knowledge, the effect of friction has been incorporated. A set of limiting situations is discussed in detail, such ... More

The Spin Gap in the Context of the Boson-Fermion Model for High $T_c$ SuperconductivityDec 18 1996The issue of the spin gap in the magnetic susceptibility $\chi''(q,\omega)$ in high T_c superconductors is discussed within a scenario of a mixture of localized tightly bound electron pairs in singlet states (bi-polarons) and itinerant electrons. Due ... More

Breakdown of Landau Fermi liquid properties in the $2D$ Boson-Fermion modelDec 07 1995We study the normal state spectral properties of the fermionic excitations in the Boson-Fermion model. The fermionic single particle excitations show a flattening of the dispersion as the Fermi vector ${\bf k}_{_F}$ is approached from below, forshadowing ... More

Trace anomalies and the $ΔI = 1/2$ ruleNov 30 2000Trace Anomaly Dominance in weak $K$-decays successfully reproduces the $\Delta I = {1\over 2}$ selection rule results, as observed in $K_S \to \pi\pi, K_L \to \pi\pi\pi, K_S \to \gamma\gamma$ and $K_L \to \pi^0 \gamma\gamma$.

Spin Waves in Canted Phases: An Application to Doped ManganitesNov 29 1999Dec 12 2000We present the effective lagrangian for low energy and momentum spin waves in canted phases at next to leading order in the derivative expansion. The symmetry breaking pattern SU(2) --> 1 of the internal spin group and that of the crystallographic space ... More

Elastic s-wave scattering phase shifts and |Vub| from lattice calculations of form factors for exclusive semileptonic decaysNov 21 2007Omnes dispersion relations make a connection between form factors for exclusive semileptonic decays and phase shifts in the corresponding elastic scattering channels. We describe two applications. In the first, we use lattice form factor calculations ... More

Stochastic MultiresonanceMar 02 1997We present a class of systems for which the signal-to-noise ratio as a function of the noise level may display a multiplicity of maxima. This phenomenon, referred to as stochastic multiresonance, indicates the possibility that periodic signals may be ... More

All tree-level amplitudes in N=4 SYMAug 19 2008Mar 16 2009We give an explicit formula for all tree amplitudes in N=4 SYM, derived by solving the recently presented supersymmetric tree-level recursion relations. The result is given in a compact, manifestly supersymmetric form and we show how to extract from it ... More

Stability of string defects in models of non-Abelian symmetry breakingJul 09 1998Aug 12 1998In this paper we describe a new type of topological defect, called a homilia string, which is stabilized via interactions with the string network. Using analytical and numerical techniques, we investigate the stability and dynamics of homilia strings, ... More

X-ray properties of active M dwarfs as observed by XMM-NewtonApr 06 2005We present a comparative study of X-ray emission from a sample of active M dwarfs with spectral types \hbox{M3.5 - M4.5} using XMM-Newton observations of two single stars, AD Leonis and EV Lacertae, and two unresolved binary systems, AT Microscopii and ... More

X-ray emission from the remarkable A-type star HR 8799Apr 08 2010We present a Chandra observation of the exceptional planet bearing A5V star HR 8799, more precisely classified as a kA5hF0mA5 star and search for intrinsic X-ray emission. We clearly detect HR 8799 at soft X-ray energies with the ACIS-S detector in a ... More

Revealing the extended radio emission from the gamma-ray binary HESS J0632+057Aug 01 2011Sep 04 2011Context. After the detection of a 321-days periodicity in X-rays, HESS J0632+057 can be robustly considered a new member of the selected group of gamma-ray binaries. These sources are known to show extended radio structure at scales of milliarcseconds ... More

O(alpha_s) Spin-Spin Correlations for Top and Bottom Quark Production in e+ e- AnnihilationJun 23 1997Oct 15 1997We present the full O(alpha_s) longitudinal spin-spin correlations for heavy-quark pair production at e+ e- high-energy colliders in closed analytical form. In such reactions, quark and antiquark have strongly correlated spins, and the longitudinal components ... More

Shades of Hyperbolicity for HamiltoniansDec 19 2012We prove that a C2 Hamiltonian system H in M is globally hyperbolic if any of the following statements holds: H is robustly topologically stable; H is stably shadowable; H is stably expansive; and H has the stable weak specification property. Moreover, ... More

Optical Control of Donor Spin Qubits in SiliconJul 28 2015Oct 26 2015We show how to achieve optical, spin-selective transitions from the ground state to excited orbital states of group-V donors (P, As, Sb, Bi) in silicon. We consider two approaches based on either resonant, far-infrared (IR) transitions of the neutral ... More

Diffuse flux of galactic neutrinos and gamma raysOct 08 2016We calculate the fluxes of neutrinos and gamma rays from interactions of cosmic rays with interstellar matter in our galaxy. We use EPOS-LHC, SIBYLL and GHEISHA to obtain the yield of these particles in proton, helium and iron collisions at kinetic energies ... More

How to separate the low amplitude delta Scuti variation from the instrumental ones in CoRoT data?Apr 01 2016Rich regular frequency patterns were found in the Fourier spectra of low-amplitude delta Scuti stars observed by CoRoT satellite (see Papar\'o et al. 2016a,b). The CoRoT observations are, however, influenced by the disturbing effect of the South Atlantic ... More

Classical information capacity of a class of quantum channelsDec 16 2004Apr 14 2005We consider the additivity of the minimal output entropy and the classical information capacity of a class of quantum channels. For this class of channels the norm of the output is maximized for the output being a normalized projection. We prove the additivity ... More

Breathers in the weakly coupled topological discrete sine-Gordon systemFeb 19 1998Jul 06 1998Existence of breather (spatially localized, time periodic, oscillatory) solutions of the topological discrete sine-Gordon (TDSG) system, in the regime of weak coupling, is proved. The novelty of this result is that, unlike the systems previously considered ... More

Good rotationsMay 20 1998Numerical integrations in celestial mechanics often involve the repeated computation of a rotation with a constant angle. A direct evaluation of these rotations yields a linear drift of the distance to the origin. This is due to roundoff in the representation ... More

The global properties of all variety of AGNDec 13 2004Active Galactic Nuclei (AGN) have been a challenging field of research for the past six decades. Nevertheless, many questions still remain unanswered today, regardless of the tremendous theoretical and technological advances. In this brief review I propose ... More

Theory of Exciton Migration and Field-Induced Dissociation in Conjugated PolymersJul 08 1996The interplay of migration, recombination, and dissociation of excitons in disordered media is studied theoretically in the low temperature regime. An exact expression for the photoluminescence spectrum is obtained. The theory is applied to describe the ... More

Kovacs effect in facilitated spin models of strong and fragile glassesAug 18 2004Nov 29 2004We investigate the Kovacs (or crossover) effect in facilitated $f$-spin models of glassy dynamics. Although the Kovacs hump shows a behavior qualitatively similar for all cases we have examined (irrespective of the facilitation parameter $f$ and the spatial ... More

Bound States of Black Holes and Other $P$-BranesMay 13 1996May 24 1996In the process of identifying heterotic and Type $II$ BPS string states with extremal dilaton black holes, it has been suggested that solutions with scalar/Maxwell parameters $a=\sqrt{3}$, $1$, $1/\sqrt{3}$ and $0$ correspond to $1-$, $2-$, $3-$ and $4$-particle ... More

Connecting Berry's phase and the pumped charge in a Cooper pair pumpMar 10 2003Apr 30 2003The properties of the tunnelling-charging Hamiltonian of a Cooper pair pump are well understood in the regime of weak and intermediate Josephson coupling, i.e. when $E_{\mathrm{J}}\lesssim E_{\mathrm{C}}$. It is also known that Berry's phase is related ... More

Isospin amplitudes and CP violation in $(B \to Kπ)$ decaysNov 25 1997We present a simple isospin invariant parametrization for $(B \to K\pi)$ decay amplitudes which consistently includes CP violation and (quasi-elastic) hadronic final states interactions. We find that the observed $(B \to K\pi)$ decays do not lead to a ... More

Phases and Amplitudes in Inclusive $Ψ$ and $Ψ'$ DecaysJun 14 1999In inclusive decays of the $\Psi$ (3097), electromagnetic and gluonic annihilation amplitudes add incoherently, namely they are 90$^\circ$ out of phase. We argue that this incoherence must persist in each exclusive decay channel. For inclusive $\Psi'$ ... More

Testing various polarized parton distributions at RHICJun 03 1997Jun 06 1997A very promising spin physics programme will be soon on the way at the BNL Relativistic Heavy Ion Collider (RHIC). By studying the spin asymmetries for various processes (single photon, single-jet and $W^{\pm}$ production), we will compare the different ... More

Effects of Fermion Flavor on Exciton Condensation in Double Layer SystemsAug 31 2011We use fermionic path integral quantum Monte Carlo to study the effects of fermion flavor on the physical properties of dipolar exciton condensates in double layer systems. We find that by including spin in the system weakens the effective interlayer ... More

Laplacian operators and Radon transforms on Grassmann graphsApr 01 2004Aug 26 2005Let $\Omega$ be a vector space over a finite field with q elements. Let G denote the general linear group of endomorphisms of $\Omega$ and let us consider the left regular representation $\rho: G \to B(L_2(X))$ associated to the natural action of G on ... More

An Asymptotic Analysis of a 2-D Model of Dynamically Active Compartments Coupled by Bulk DiffusionNov 10 2015A class of coupled cell-bulk ODE-PDE models is formulated and analyzed in a two-dimensional domain, which is relevant to studying quorum sensing behavior on thin substrates. In this model, spatially segregated dynamically active signaling cells of a common ... More

New X-ray observations of IQ Aurigae and alpha2 Canum Venaticorum - Probing the magnetically channelled wind shock model in A0p starsMay 18 2011We present new X-ray observations of the A0p stars alpha^2 CVn (log Lx < 26.0 erg/s) and IQ Aur (log Lx = 29.6 erg/s) and find that their X-ray luminosities differ by at least three orders of magnitude. IQ Aur possesses a strong cool plasma component ... More

Hyperbolicity and Stability for Hamiltonian flowsApr 05 2012We prove that a Hamiltonian star system, defined on a 2d-dimensional symplectic manifold M, is Anosov. As a consequence we obtain the proof of the stability conjecture for Hamiltonians. This generalizes the 4-dimensional results in [6].

Periodic morphological changes in gamma-ray binariesOct 29 2012Gamma-ray binaries allow us to study physical processes such as particle acceleration up to very-high energies and gamma-ray emission and absorption with changing geometrical configurations on a periodic basis. They produce outflows of radio-emitting ... More

Double Gate Bias Dependency of Low Temperature Conductivity of SiO2-Si-SiO2 Quantum WellsNov 28 2006The gate bias dependency of conductivity is examined in two Si quantum wells with well thickness tw = 7 nm and tw = 14 nm. The conductivity of the thinner device behaves smoothly whereas the thicker device shows strong non-monotonic features as a function ... More

Highly optimized tolerance and power laws in dense and sparse resource regimesApr 20 2005Power law cumulative frequency $(P)$ vs. event size $(l)$ distributions $P(\geq l)\sim l^{-\alpha}$ are frequently cited as evidence for complexity and serve as a starting point for linking theoretical models and mechanisms with observed data. Systems ... More

LEP1 vs. Future Colliders: Effective Operators And Extended Gauge GroupJul 24 1992In an effective Lagrangian approach to physics beyond the Standard Model, it has been argued that imposing $SU(2) \times U(1)$ invariance severely restricts the discovery potential of future colliders. We exhibit a possible way out in an extended gauge ... More

The free surface of superfluid 4He at zero temperatureMar 21 2005The structure and energetics of the free surface of superfluid $^4$He are studied using the diffusion Monte Carlo method. Extending a previous calculation by Vall\'es and Schmidt, which used the Green's function Monte Carlo method, we study the surface ... More

Thouless Energy and Correlations of QCD Dirac EigenvaluesMar 23 1998Mar 31 1998Eigenvalues and eigenfunctions of the QCD Dirac operator are studied for gauge field configurations given by a liquid of instantons. We find that for energy differences $\delta E$ below an energy scale $E_c$ the eigenvalue correlations are given by Random ... More

On the study of jamming percolationAug 05 2007Sep 12 2007We investigate kinetically constrained models of glassy transitions, and determine which model characteristics are crucial in allowing a rigorous proof that such models have discontinuous transitions with faster than power law diverging length and time ... More

On the study of force-balance percolationJun 10 2008We study models of correlated percolation where there are constraints on the occupation of sites that mimic force-balance, i.e. for a site to be stable requires occupied neighboring sites in all four compass directions in two dimensions. We prove rigorously ... More

Comment on ``Jamming Percolation and Glass Transitions in Lattice Models.''Dec 19 2006Toninelli, Biroli, and Fisher recently introduced the knights model, a correlated percolation system (Phys. Rev. Lett. 96, 035702 (2006)). They claimed to prove that the critical point of this model was the same as that for directed percolation, and then ... More

Mechanical switching of ferro-electric rubberDec 09 2008At the A to C transition, smectic elastomers have recently been observed to undergo $\sim$35% spontaneous shear strains. We first explicitly describe how strains of up to twice this value could be mechanically or electrically induced in Sm-$C$ elastomers ... More

A numerical simulation of the evolution and fate of a FRI jet. The case of 3C 31Sep 12 2007The evolution of FRI jets has been long studied in the framework of the FRI-FRII dichotomy. In this paper, we test the present theoretical and observational models via a relativistic numerical simulation of the jets in the radio galaxy 3C 31. We use the ... More

Existence de filtrations admissibles sur des isocristauxApr 24 2002Let (D,phi) be an isocrystal over an algebraically closed field of characteristic p. Let F^bullet be a filtration on D. If F^bullet is (weakly) admissible, its type vector is greater or equal to the slope vector of (D,phi). We prove that conversely, give ... More

Quasars at z=6: the survival of the fittestJul 05 2006The Sloan Digital Sky survey detected luminous quasars at very high redshift, z>6. Follow-up observations indicated that at least some of these quasars are powered by supermassive black holes (SMBHs) with masses in excess of billion solar masses. SMBHs, ... More

Mass transfer variation in the outburst model of dwarf novae and soft X-ray transientsJul 30 2008We discuss two mechanisms that could result in an enhancement of the mass transfer rate during outbursts of dwarf novae and soft X-ray transients: the hot outer disc rim itself could heat the L1 point and scattered radiation by optically thin outflowing ... More

Observable Effects of Dust Formation in Dynamic Atmospheres of M-type Mira VariablesJan 18 2006The formation of dust with temperature-dependent non-grey opacity is considered in a series of self-consistent model atmospheres at different phases of an O-rich Mira variable of mass 1.2 $M_\odot$. Photometric and interferometric properties of these ... More

Theory of Electric Field-Induced Photoluminescence Quenching in Disordered Molecular SolidsFeb 12 1998The dynamics of excitons in disordered molecular solids is studied theoretically, taking into account migration between different sites, recombination, and dissociation into free charge carriers in the presence of an electric field. The theory is applied ... More

The Adsorption of H2O on TiO2 and SnO2(110) Studied by First-Principles CalculationsAug 24 1995First-principles calculations based on density functional theory and the pseudopotential method have been used to investigate the energetics of H$_2$O adsorption on the (110) surface of TiO$_2$ and SnO$_2$. Full relaxation of all atomic positions is performed ... More

Domino MagnificationJan 03 2013Jan 28 2013The conditions are investigated under which a row of increasing dominoes is able to keep tumbling over. The analysis is restricted to the simplest case of frictionless dominoes that only can topple not slide. The model is scale invariant, i.e. dominoes ... More

Continuum Double Exchange ModelOct 29 1998Jun 18 1999We present a continuum model for doped manganites which consist of two species of quantum spin 1/2 fermions interacting with classical spin fields. The phase structure at zero temperature turns out to be considerably rich: antiferromagnetic insulator, ... More

Effective Field Theory Approach to Ferromagnets and Antiferromagnets in Crystaline SolidsSep 26 1997Jun 18 1999We present a systematic construction of effective lagrangians for the low energy and momentum region of ferromagnetic and antiferromagnetic spin waves in crystalline solids. We fully exploit the spontaneous symmetry breaking pattern $SU(2)\to U(1)$, the ... More

Ion beam requirements for fast ignition of inertial fusion targetsDec 31 2014Jan 15 2015Ion beam requirements for fast ignition are investigated by numerical simulation taking into account new effects such as ion beam divergence not included before. We assume that ions are generated by the TNSA scheme in a curved foil placed inside a re-entrant ... More

Catalogue of Be/X-ray binary systems in the Small Magellanic Cloud: X-ray, optical & IR propertiesJun 05 2015This is a catalogue of approximately 70 X-ray emitting binary systems in the Small Magellanic Cloud (SMC) that contain a Be star as the mass donor in the system and a clear X-ray pulse signature from a neutron star. The systems are generally referred ... More

Generating of an electric potential on the Moon by Cosmic rays and Solar Wind?Aug 12 2010We investigate the possibility that the Moon develops an electric potential originating from the impinging particles on the Moon from cosmic rays and solar wind. The investigation includes all experimental data of the flux of charged particle for energies ... More

AIS-BN: An Adaptive Importance Sampling Algorithm for Evidential Reasoning in Large Bayesian NetworksJun 01 2011Stochastic sampling algorithms, while an attractive alternative to exact algorithms in very large Bayesian network models, have been observed to perform poorly in evidential reasoning with extremely unlikely evidence. To address this problem, we propose ... More

Effect of the Output of the System in Signal DetectionMar 02 1997We analyze the consequences that the choice of the output of the system has in the efficiency of signal detection. It is shown that the signal and the signal-to-noise ratio (SNR), used to characterize the phenomenon of stochastic resonance, strongly depend ... More

Simple loop integrals and amplitudes in N=4 SYMAug 17 2010We use momentum twistors to evaluate planar loop integrals. Infrared divergences are regulated by the recently proposed AdS-inspired mass regulator. We show that two-loop amplitudes in N=4 super Yang-Mills can be expanded in terms of basis integrals having ... More

Quantum state of two trapped Bose-Einstein condensates with a Josephson couplingOct 14 1997We consider the precise quantum state of two trapped, coupled Bose Einstein condensates in the two-mode approximation. We seek a representation of the state in terms of a Wigner-like distribution on the two-mode Bloch sphere. The problem is solved using ... More

Correlation-driven multigap d-wave superconductivity in Anderson lattice modelOct 01 2015We present the full Gutzwiller-wave-function solution of the Anderson lattice model in two dimensions that leads to the correlation-driven multigap superconducting (SC) ground state with the dominant $d_{x^2-y^2}$-wave symmetry. The results are consistent ... More

A deep XMM-Newton X-ray observation of the Chamaeleon I dark cloudOct 26 2006Methods. The northern-eastern fringe of the Chameleon I dark cloud was observed with XMM-Newton, revisiting a region observed with ROSAT 15 years ago. Centered on the extended X-ray source CHXR49 we are able to resolve it into three major contributing ... More

Quiescent X-ray emission from the M9 dwarf LHS 2065Jun 24 2008We investigate an archival XMM-Newton observation of LHS 2065, an ultracool dwarf with spectral type M9. We clearly detect LHS 2065 at soft X-ray energies in less than 1 h effective exposure time above the 3 sigma level with the PN and MOS1 detector. ... More

Universal fluctuations in spectra of the lattice Dirac operatorJan 21 1995Recently, Kalkreuter obtained the complete Dirac spectrum for an $SU(2)$ lattice gauge theory with dynamical staggered fermions on a $12^4$ lattice for $\beta =1.8$ and $\beta=2.8$. We performed a statistical analysis of his data and found that the eigenvalue ... More

A search for microquasar candidates at low galactic latitudesJan 23 2004Recent studies of relativistic jet sources in the Galaxy, also known as microquasars, have been very useful in trying to understand the accretion/ejection processes that take place near compact objects. However, the number of sources involved in such ... More

Umklapp scattering from spin fluctuations in Copper-OxidesMay 16 1995May 18 1995The $\mathbf k$-dependent electronic momentum relaxation rate due to Umklapp scattering from antiferromagnetic spin fluctuations is studied within a renormalized mean-field approach to an extended $t-J$ model appropriate to YBa$_2$Cu$_3$O$_{7-x}$ and ... More