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Results for "G. -P. Hao"

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A high-order Nystrom discretization scheme for boundary integral equations defined on rotationally symmetric surfacesDec 30 2011A scheme for rapidly and accurately computing solutions to boundary integral equations (BIEs) on rotationally symmetric surfaces in R^3 is presented. The scheme uses the Fourier transform to reduce the original BIE defined on a surface to a sequence of ... More
High-order accurate Nystrom discretization of integral equations with weakly singular kernels on smooth curves in the planeDec 29 2011Nov 21 2012Boundary integral equations and Nystrom discretization provide a powerful tool for the solution of Laplace and Helmholtz boundary value problems. However, often a weakly-singular kernel arises, in which case specialized quadratures that modify the matrix ... More
Bosonic Many-body Theory of Quantum Spin IceSep 17 2014Feb 12 2015We carry out an analytical study of quantum spin ice, a U$(1)$ quantum spin liquid close to the classical spin ice solution for an effective spin $1/2$ model with anisotropic exchange couplings $J_{zz}$, $J_{\pm}$ and $J_{z\pm}$ on the pyrochlore lattice. ... More
Order-by-disorder near criticality in $XY$ pyrochlore magnetsJun 18 2015We consider a system of spins on the sites of a three-dimensional pyrochlore lattice of corner-sharing tetrahedra interacting with a predominant effective $xy$ exchange. In particular, we investigate the selection of a long-range ordered state with broken ... More
A Cold Atomic Fermi Gas with a Spatially Modulated InteractionOct 30 2006Oct 31 2006We study an ultra-cold atomic Fermi Gas with the atom-atom interaction modulated periodically in space. A novel ground state with cooper pairs occupying non-zero center of mass momenta is found. Such a state is closely related to the state proposed by ... More
A Tonks Giradeau Gas in the Presence of a Local PotentialFeb 07 2006The physics of a Tonks-Giradeau Gas in the presence of a local potential is studied. In order to evaluate the single particle density matrix (SPDM) of the many-body ground state, the Wiger-Jordan transformation is used. The eigenvector with the largest ... More
Observation of an in-plane magnetic-field-driven phase transition in a quantum Hall system with SU(4) symmetrySep 10 2007Sep 11 2007In condensed matter physics, the study of electronic states with SU(N) symmetry has attracted considerable and growing attention in recent years, as systems with such a symmetry can often have a spontaneous symmetry-breaking effect giving rise to a novel ... More
Probing Quantum Hall Pseudospin Ferromagnet by Resistively Detected NMRApr 06 2009Resistively Detected Nuclear Magnetic Resonance (RD-NMR) has been used to investigate a two-subband electron system in a regime where quantum Hall pseudo-spin ferromagnetic (QHPF) states are prominently developed. It reveals that the easy-axis QHPF state ... More
Experimental Studies of Scaling Behavior of a Quantum Hall System with a Tunable Landau Level MixingJul 02 2008Temperature dependence of the longitudinal and Hall resistance is studied in the regime of localization-delocalization transition. We carry out measurements of a scaling exponent $\kappa$ in the Landau level mixing region at several filling factors. The ... More
Microscopic Theory of Spontaneous Decay in a DielectricJul 21 2005May 29 2006The local field correction to the spontanous dacay rate of an impurity source atom imbedded in a disordered dielectric is calculated to second order in the dielectric density. The result is found to differ from predictions associated with both "virtual" ... More
A Possible Late Time $Λ$CDM-like Background Cosmology in Relativistic MOND TheoryApr 05 2005Mar 28 2009In the framework of Relativistic MOND theory (TeVeS), we show that a late time background $\Lambda$CDM cosmology can be attained by choosing a specific $F(\mu)$ that also meets the requirement for the existence of Newtonian and MOND limits. We investigate ... More
Multiple imputation for sharing precise geographies in public use dataMar 19 2012When releasing data to the public, data stewards are ethically and often legally obligated to protect the confidentiality of data subjects' identities and sensitive attributes. They also strive to release data that are informative for a wide range of ... More
Microscopic Theory of the Photon Recoil of an Atom in a DielectricMay 29 2006Oct 27 2006An atom recoils when it undergoes spontaneous decay. In this paper we present a microscopic calculation of the recoil of a source atom imbedded in a dielectric medium. We find that the source atom recoils with the canonical photon momentum $n\hbar k_{0,}$ ... More
Out-of-Plane Mechanical Properties of 2D Hybrid Organic-Inorganic Perovskites by NanoindentationMar 29 2018Jun 08 20182D layered hybrid organic-inorganic perovskites (HOIPs) have demonstrated improved stability and promising photovoltaic performance. The mechanical properties of such functional materials are both fundamentally and practically important to achieve both ... More
First-principles study of native point defects in Bi2Se3Jun 30 2012Using first-principles method within the framework of the density functional theory, we study the influence of native point defect on the structural and electronic properties of Bi$_2$Se$_3$. Se vacancy in Bi$_2$Se$_3$ is a double donor, and Bi vacancy ... More
Free spectral range electrical tuning of a high quality on-chip microcavityJun 20 2018Reconfigurable photonic circuits have applications ranging from next-generation computer architectures to quantum networks, coherent radar and optical metamaterials. However, complete reconfigurability is only currently practical on millimetre-scale device ... More
SPDA: Superpixel-based Data Augmentation for Biomedical Image SegmentationFeb 28 2019Supervised training a deep neural network aims to "teach" the network to mimic human visual perception that is represented by image-and-label pairs in the training data. Superpixelized (SP) images are visually perceivable to humans, but a conventionally ... More
Molecule States in a Gate Tunable Graphene Double Quantum DotNov 24 2010We have measured a graphene double quantum dot device with multiple electrostatic gates that are used to enhance control to investigate it. At low temperatures the transport measurements reveal honeycomb charge stability diagrams which can be tuned from ... More
Stability Margin Scaling Laws for Distributed Formation Control as a Function of Network StructureMay 03 2010Oct 12 2010We consider the problem of distributed formation control of a large number of vehicles. An individual vehicle in the formation is assumed to be a fully actuated point mass. A distributed control law is examined: the control action on an individual vehicle ... More
Quantum Kagome IceJun 30 2014Actively shought since the turn of the century, two-dimensional quantum spin liquids (QSLs) are exotic phases of matter where magnetic moments remain disordered even at extremely low temperatures. Despite ongoing searches, QSLs remain elusive, due to ... More
Refrustration and competing orders in the prototypical Dy2Ti2O7 spin ice materialDec 16 2015Spin ices, frustrated magnetic materials analogous to common water ice, are exemplars of high frustration in three dimensions. Recent experimental studies of the low-temperature properties of the paradigmatic Dy$_2$Ti$_2$O$_7$ spin ice material, in particular ... More
Neutron spectroscopic study of crystal field excitations in Tb2Ti2O7 and Tb2Sn2O7Oct 11 2013Apr 30 2014We present time-of-flight inelastic neutron scattering measurements at low temperature on powder samples of the magnetic pyrochlore oxides Tb2Ti2O7 and Tb2Sn2O7. These two materials possess related, but different ground states, with Tb2Sn2O7 displaying ... More
Generative Semantic Manipulation with Contrasting GANAug 01 2017Generative Adversarial Networks (GANs) have recently achieved significant improvement on paired/unpaired image-to-image translation, such as photo$\rightarrow$ sketch and artist painting style transfer. However, existing models can only be capable of ... More
Understanding the LIGO GW150914 eventApr 21 2016Aug 09 2016We present a simplified method for the extraction of meaningful signals from Hanford and Livingstone 32 seconds data for the GW150914 event made publicly available by the LIGO collaboration and demonstrate its ability to reproduce the LIGO collaboration's ... More
Soft Label Memorization-Generalization for Natural Language InferenceFeb 27 2017Jan 25 2019Often when multiple labels are obtained for a training example it is assumed that there is an element of noise that must be accounted for. It has been shown that this disagreement can be considered signal instead of noise. In this work we investigate ... More
Development of an Advanced Automated Method for Solar Filament Recognition and Its Scientific Application to a Solar Cycle of MLSO Hα\ DataMar 26 2013We developed a method to automatically detect and trace solar filaments in H\alpha\ full-disk images. The program is able not only to recognize filaments and determine their properties, such as the position, the area, the spine, and other relevant parameters, ... More
Repairing without Retraining: Avoiding Disparate Impact with Counterfactual DistributionsJan 29 2019When the average performance of a prediction model varies significantly with respect to a sensitive attribute (e.g., race or gender), the performance disparity can be expressed in terms of the probability distributions of input and output variables for ... More
Impedance Spectra of Mixed Conductors: a 2D Study of CeriaMar 21 2009Apr 16 2009In this paper we develop an analytical framework for the study of electrochemical impedance of mixed ionic and electronic conductors (MIEC). The framework is based on first-principles and it features the coupling of electrochemical reactions, surface ... More
Coannihilation with a chargino and gauge boson pair production at one-loopSep 17 2009Sep 18 2009We present a complete calculation of the electroweak one-loop corrections to the relic density within the MSSM framework. In the context of the neutralino as dark matter candidate, we review different scenarios of annihilation and coannihilation with ... More
The CPA Equation of State and an Activity Coefficient Model for Accurate Molar Enthalpy Calculations of Mixtures with Carbon Dioxide and Water/BrineApr 20 2015Thermodynamic property calculations of mixtures containing carbon dioxide (CO$_2$) and water, including brines, are essential in theoretical models of many natural and industrial processes. The properties of greatest practical interest are density, solubility, ... More
Repairing without Retraining: Avoiding Disparate Impact with Counterfactual DistributionsJan 29 2019May 17 2019When the performance of a machine learning model varies over groups defined by sensitive attributes (e.g., gender or ethnicity), the performance disparity can be expressed in terms of the probability distributions of the input and output variables over ... More
On the Direction of Discrimination: An Information-Theoretic Analysis of Disparate Impact in Machine LearningJan 16 2018In the context of machine learning, disparate impact refers to a form of systematic discrimination whereby the output distribution of a model depends on the value of a sensitive attribute (e.g., race or gender). In this paper, we present an information-theoretic ... More
Building an Evaluation Scale using Item Response TheoryMay 28 2016Sep 23 2016Evaluation of NLP methods requires testing against a previously vetted gold-standard test set and reporting standard metrics (accuracy/precision/recall/F1). The current assumption is that all items in a given test set are equal with regards to difficulty ... More
Automated Detection Methods for Solar Activities and an Application for Statistic Analysis of Solar FilamentApr 10 2018With the rapid development of telescopes, both temporal cadence and the spatial resolution of observations are increasing. This in turn generates vast amount of data, which can be efficiently searched only with automated detections in order to derive ... More
Atomically-thin micas as proton conducting membranesJun 11 2019Monolayers of graphene and hexagonal boron nitride (hBN) are highly permeable to thermal protons. For thicker two-dimensional (2D) materials, proton conductivity diminishes exponentially so that, for example, monolayer MoS2 that is just three atoms thick ... More
From Hunds insulator to Fermi liquid: Optical spectroscopy study of K doping in BaMn$_2$As$_2$Sep 22 2015We present optical transmission measurements that reveal a charge gap of 0.86 eV in the local moment antiferromagnetic insulator BaMn$_2$As$_2$, an order of magnitude larger than previously reported. Density functional theory plus dynamical mean field ... More
Dynamics, Structure and Glass Formation of Calcium Aluminate LiquidsDec 22 2017Crystalline calcium-aluminates include the phases essential in the setting of Portland cements developed over the last century. It is only within recent decades, however, that calcium-aluminate melts and glasses have begun to attract attention, bringing ... More
"Anomalous" Optical GRB Afterglows are Common: Two z~4 Bursts, GRB 060206 and 060210Feb 23 2006Dec 04 2006We report on two recent z~4 gamma-ray bursts (GRBs), GRB 060206 and GRB 060210, for which we have obtained well-sampled optical light curves. Our data, combined with early optical data reported in the literature, shows unusual behavior for both afterglows. ... More
ZM-Net: Real-time Zero-shot Image Manipulation NetworkMar 21 2017Mar 22 2017Many problems in image processing and computer vision (e.g. colorization, style transfer) can be posed as 'manipulating' an input image into a corresponding output image given a user-specified guiding signal. A holy-grail solution towards generic image ... More
Fractional quantum Hall states of bosons on conesSep 22 2016Sep 26 2016Motivated by a recent experiment which synthesizes Landau levels for photons on cones [Schine {\em et al.}, Nature 534, 671 (2016)], and more generally the interest in understanding gravitational responses of quantum Hall systems, we study fractional ... More
Distributed $(Δ+1)$-Coloring in Sublogarithmic RoundsMar 04 2016Jan 17 2018We give a new randomized distributed algorithm for $(\Delta+1)$-coloring in the LOCAL model, running in $O(\sqrt{\log \Delta})+ 2^{O(\sqrt{\log \log n})}$ rounds in a graph of maximum degree~$\Delta$. This implies that the $(\Delta+1)$-coloring problem ... More
Nematicity in stripe ordered cuprates probed via resonant x-ray scatteringFeb 05 2016In underdoped cuprate superconductors, a rich competition occurs between superconductivity and charge density wave (CDW) order. Whether rotational symmetry breaking (nematicity) occurs intrinsically and generically or as a consequence of other orders ... More
Report of the Subgroup on the Top QuarkNov 04 1993The top group studied discovery issues as well as measurements to be made at the Tevatron, the LHC and the SSC.
Relic density at one-loop with gauge boson pair productionOct 19 2009Oct 23 2009We have computed the full one-loop corrections (electroweak as well as QCD) to processes contributing to the relic density of dark matter in the MSSM where the LSP is the lightest neutralino. We cover scenarios where the most important channels are those ... More
Distributed $(Δ+1)$-Coloring in Sublogarithmic RoundsMar 04 2016The $(\Delta+1)$-coloring problem is a fundamental symmetry breaking problem in distributed computing. We give a new randomized coloring algorithm for $(\Delta+1)$-coloring running in $O(\sqrt{\log \Delta})+ 2^{O(\sqrt{\log \log n})}$ rounds with probability ... More
Adaptive Detection of Point-like Targets in Spectrally Symmetric InterferenceNov 23 2015We address adaptive radar detection of targets embedded in ground clutter dominated environments characterized by a symmetrically structured power spectral density. At the design stage, we leverage on the spectrum symmetry for the interference to come ... More
Fractional quantum Hall states of bosons on conesSep 22 2016Sep 19 2017Motivated by a recent experiment which synthesizes Landau levels for photons on cones [Schine {\em et al.}, Nature 534, 671 (2016)], and more generally the interest in understanding gravitational responses of quantum Hall states, we study fractional quantum ... More
A practical light transport system model for chemiluminescence distribution reconstructionDec 08 2018Plenoptic cameras and other integral photography instruments capture richer angular information from a scene than traditional 2D cameras. This extra information is used to estimate depth, perform superresolution or reconstruct 3D information from the ... More
Nucleation in aqueous NaCl solutions shifts from 1-step to 2-step mechanism on crossing the spinodalDec 07 2018Dec 25 2018In this work, we use large-scale molecular dynamics simulations coupled to free energy calculations to identify for the first time a limit of stability (spinodal) and a change in the nucleation mechanism in aqueous NaCl solutions. This is a system of ... More
Getting in shape and swimming: the role of cortical forces and membrane heterogeneity in eukaryotic cellsOct 04 2017May 23 2018Recent research has shown that motile cells can adapt their mode of propulsion to the mechanical properties of the environment in which they find themselves--crawling in some environments while swimming in others. The latter can involve movement by blebbing ... More
Distributed computation of equilibria in misspecified convex stochastic Nash gamesAug 25 2013Oct 11 2015The distributed computation of Nash equilibria is assuming growing relevance in engineering where such problems emerge in the context of distributed control. Accordingly, we consider static stochastic convex games complicated by a parametric misspecification, ... More
Global Analysis of General SU(2) x SU(2) x U(1) Models with Precision DataMar 17 2010We present the results of a global analysis of a class of models with an extended electroweak gauge group of the form SU(2) x SU(2) x U(1), often denoted as G(221) models, which include as examples the left-right, the lepto-phobic, the hadro-phobic, the ... More
The Utility Cost of Robust Privacy GuaranteesJan 18 2018May 10 2018Consider a data publishing setting for a data set with public and private features. The objective of the publisher is to maximize the amount of information about the public features in a revealed data set, while keeping the information leaked about the ... More
Understanding Deep Learning Performance through an Examination of Test Set Difficulty: A Psychometric Case StudyFeb 15 2017Sep 07 2018Interpreting the performance of deep learning models beyond test set accuracy is challenging. Characteristics of individual data points are often not considered during evaluation, and each data point is treated equally. We examine the impact of a test ... More
Two-dimensional ${J}_{\rm eff}$ = 1/2 antiferromagnetic insulator unraveled from interlayer exchange coupling in artificial perovskite iridate superlatticesMar 14 2017Aug 01 2017We report an experimental investigation of the two-dimensional ${J}_{\rm eff}$ = 1/2 antiferromagnetic Mott insulator by varying the interlayer exchange coupling in [(SrIrO$_3$)$_1$, (SrTiO$_3$)$_m$] ($m$ = 1, 2 and 3) superlattices. Although all samples ... More
Quantum transport in Majorana nanowire devices: next stepsMay 20 2019Majorana zero modes are localized quasiparticles that obey non-Abelian exchange statistics. Braiding Majorana zero modes forms the basis of topologically protected quantum operations which could in principle significantly reduce qubit decoherence and ... More
Novel spin-orbit coupling driven emergent states in iridate-based heterostructuresNov 21 2017Recent years have seen many examples of how the strong spin-orbit coupling (SOC) present in iridates can stabilize new emergent states that are difficult or impossible to realize in more conventional materials. In this review we outline a representative ... More
On the Robustness of Information-Theoretic Privacy Measures and MechanismsNov 14 2018Consider a data publishing setting for a dataset composed of non-private features correlated with a set of private features not necessarily present in the dataset. The objective of the publisher is to maximize the amount of information about the non-private ... More
Real-time On-Demand Crowd-powered Entity ExtractionApr 12 2017Dec 06 2017Output-agreement mechanisms such as ESP Game have been widely used in human computation to obtain reliable human-generated labels. In this paper, we argue that a "time-limited" output-agreement mechanism can be used to create a fast and robust crowd-powered ... More
Ground State Phase Diagram of Generic XY Pyrochlore Magnets with Quantum FluctuationsNov 13 2013Motivated by recent experimental and theoretical progress on the Er2Ti2O7 pyrochlore XY antiferromagnet, we study the problem of quantum order-by-disorder in pyrochlore XY systems. We consider the most general nearest-neighbor pseudo spin-1/2 Hamiltonian ... More
Simulating the Transverse Ising Model on a Quantum Computer: Error Correction with the Surface CodeSep 29 2012Mar 29 2013We estimate the resource requirements for the quantum simulation of the ground state energy of the one dimensional quantum transverse Ising model (TIM), based on the surface code implementation of a fault tolerant quantum computer. The surface code approach ... More
Evorus: A Crowd-powered Conversational Assistant Built to Automate Itself Over TimeJan 08 2018Jan 10 2018Crowd-powered conversational assistants have been shown to be more robust than automated systems, but do so at the cost of higher response latency and monetary costs. A promising direction is to combine the two approaches for high quality, low latency, ... More
Diversity of hysteresis in a fully cooperative coinfection modelApr 11 2017We propose a fully cooperative coinfection model in which singly infected individuals are more likely to acquire a second disease than those who are susceptible, and doubly infected individuals are also assumed to be more contagious than those infected ... More
Bayesian quantile additive regression treesJul 10 2016Ensemble of regression trees have become popular statistical tools for the estimation of conditional mean given a set of predictors. However, quantile regression trees and their ensembles have not yet garnered much attention despite the increasing popularity ... More
The Utility Cost of Robust Privacy GuaranteesJan 18 2018Consider a data publishing setting for a data set with public and private features. The objective of the publisher is to maximize the amount of information about the public features in a revealed data set, while keeping the information leaked about the ... More
Parity restoration in the Highly Truncated Diagonalization Approach: application to the outer fission barrier of $^{240}$PuOct 01 2012The restoration of the parity symmetry has been performed in the framework of the Highly Truncated Diagonalization Approach suited to treat correlations in an explicitly particle-number conserving microscopic approach. To do so we have assumed axial symmetry ... More
Long-term and blow-up behaviors of exponential moments in multi-dimensional affine diffusionsOct 14 2010May 15 2012This paper considers multi-dimensional affine processes with continuous sample paths. By analyzing the Riccati system, which is associated with affine processes via the transform formula, we fully characterize the regions of exponents in which exponential ... More
Fluctuation-Driven Selection at Criticality in a Frustrated Magnetic System: the Case of Multiple-k Partial Order on the Pyrochlore LatticeOct 18 2013We study the problem of partially ordered phases with periodically arranged disordered (paramagnetic) sites on the pyrochlore lattice, a network of corner-sharing tetrahedra. The periodicity of these phases is characterized by one or more wave vectors ... More
Distributed computation of equilibria in misspecified convex stochastic Nash gamesAug 25 2013Oct 14 2017The distributed computation of Nash equilibria is assuming growing relevance in engineering where such problems emerge in the context of distributed control. Accordingly, we present schemes for computing equilibria of two classes of static stochastic ... More
Statistical Analysis of Filament Features Based on the Hα Solar Images from 1988 to 2013 by Computer Automated Detection MethodNov 15 2015We improve our filament automated detection method which was proposed in our previous works. It is then applied to process the full disk H$\alpha$ data mainly obtained by Big Bear Solar Observatory (BBSO) from 1988 to 2013, spanning nearly 3 solar cycles. ... More
Nature of weak magnetism in SrTiO3/LaAlO3 multilayersNov 21 2012We report the observation of weak magnetism in superlattices of LaAlO3/SrTiO3 using beta-detected nuclear magnetic resonance. The spin lattice relaxation rate of 8 Li in superlattices with a spacer layers of 8 and 6 unit cells of LaAlO3 exhibits a strong ... More
Mode Structure in Superconducting Metamaterial Transmission Line ResonatorsDec 06 2018May 31 2019Superconducting metamaterials are a promising resource for quantum information science. In the context of circuit QED, they provide a means to engineer on-chip, novel dispersion relations and a band structure that could ultimately be utilized for generating ... More
Strongly Variable z=1.48 FeII and MgII Absorption in the Spectra of z=4.05 GRB 060206Dec 15 2006Mar 20 2007We report on the discovery of strongly variable FeII and MgII absorption lines seen at z=1.48 in the spectra of the z=4.05 GRB 060206 obtained between 4.13 to 7.63 hours (observer frame) after the burst. In particular, the FeII line equivalent width (EW) ... More
Mode Structure in Superconducting Metamaterial Transmission Line ResonatorsDec 06 2018Superconducting metamaterials are a promising resource for quantum information science. In the context of circuit QED, they provide a means to engineer on-chip, novel dispersion relations and a band structure that could ultimately be utilized for generating ... More
Observations and analysis of phase scintillation of spacecraft signal on the interplanetary plasmaMar 10 2014Aims. The phase scintillation of the European Space Agency's (ESA) Venus Express (VEX) spacecraft telemetry signal was observed at X-band (\lambda = 3.6 cm) with a number of radio telescopes of the European VLBI Network (EVN) in the period 2009-2013. ... More
Strong, anisotropic anomalous Hall effect and spin Hall effect in chiral antiferromagnetic compounds Mn$_3X$ ($X$ = Ge, Sn, Ga, Ir, Rh and Pt)Oct 13 2016We have carried out a comprehensive study of the intrinsic anomalous Hall effect and spin Hall effect of several chiral antiferromagnetic compounds, Mn$_3X$ ($X$ = Ge, Sn, Ga, Ir, Rh and Pt) by $ab~initio$ band structure and Berry phase calculations. ... More
Strong, anisotropic anomalous Hall effect and spin Hall effect in chiral antiferromagnetic compounds Mn$_3X$ ($X$ = Ge, Sn, Ga, Ir, Rh and Pt)Oct 13 2016Apr 04 2017We have carried out a comprehensive study of the intrinsic anomalous Hall effect and spin Hall effect of several chiral antiferromagnetic compounds, Mn$_3X$ ($X$ = Ge, Sn, Ga, Ir, Rh and Pt) by $ab~initio$ band structure and Berry phase calculations. ... More
Material supply and magnetic configuration of an active region filamentJan 10 2017It is important to study the fine structures of solar filaments with high-resolution observations since it can help us understand the magnetic and thermal structures of the filaments and their dynamics. In this paper, we study a newly-formed filament ... More
Agent Madoff: A Heuristic-Based Negotiation Agent For The Diplomacy Strategy GameFeb 19 2019In this paper, we present the strategy of Agent Madoff, which is a heuristic-based negotiation agent that won 2nd place at the Automated Negotiating Agents Competition (ANAC 2017). Agent Madoff is implemented to play the game Diplomacy, which is a strategic ... More
Distinct turbulence saturation regimes in stellaratorsMar 09 2017Sep 29 2017In the complex 3D magnetic fields of stellarators, ion-temperature-gradient turbulence is shown to have two distinct saturation regimes, as revealed by petascale numerical simulations, and explained by a simple turbulence theory. The first regime is marked ... More
On the Covariance of the Mixmaster ChaoticityFeb 05 2001We analyze the dynamics of the Mixmaster Universe on the base of a standard Arnowitt-Deser-Misner Hamiltonian approach showing how its asymptotic evolution to the cosmological singularity is isomorphic to a billiard on the Lobachevsky plane. The key result ... More
Structure functions for large $x$ and renormalization of Wilson loopsOct 30 1992Feb 04 2005We discuss the relation between partonic distributions near the phase space boundary and Wilson loop expectation values calculated along paths partially lying on the light-cone. Due to additional light-cone singularities, multiplicative renormalizability ... More
Tensor Mode Backreaction During Slow-roll InflationMay 15 2014Aug 15 2014We consider the backreaction of the long wavelength tensor modes produced during a slow-roll inflationary regime driven by a single scalar field in a spatially flat Friedmann-Lema\^{\i}tre-Robertson-Walker background geometry. We investigate the effects ... More
Ultra-compact (X-ray) binariesMay 30 2006A short review of ultra-compact binaries, focused on ultra-compact X-ray binaries, is followed by a discussion of recent results of our VLT campaign to obtain optical spectra of (candidate) ultra-compact X-ray binaries. We find evidence for carbon/oxygen ... More
p-wave and d-wave superconductivity in quasi-two-dimensional metalsJun 07 1999We compare predictions of the mean-field theory of superconductivity for nearly antiferromagnetic and nearly ferromagnetic metals in two dimensions. The calculations are based on a parametrization of the effective interaction arising from the exchange ... More
Multiple scales analysis of slow--fast quasilinear systemsMar 13 2019This article illustrates the application of multiple scales analysis to two archetypal quasilinear systems; i.e. to systems involving fast dynamical modes, called fluctuations, that are not directly influenced by fluctuation--fluctuation nonlinearities ... More
The universal instability in general geometryJun 30 2015The "universal" instability has recently been revived by Landreman, Antonsen and Dorland [1], who showed that it indeed exists in plasma geometries with straight (but sheared) magnetic field lines. Here it is demonstrated analytically that this instability ... More
The distances to Galactic low-mass X-ray binaries: consequences for black hole luminosities and kicksJul 08 2004We investigated the reported distances of Galactic black hole (BH) and neutron star low-mass X-ray binaries (LMXBs). Comparing the distances derived for the neutron stars CygX-2 and XTE J2123-058 using the observed Eddington limited photospheric radius ... More
Power corrections and the interplay between perturbative and non-perturbative phenomenaSep 10 1999We discuss the issue of interplay between perturbative and non-perturbative phenomena for power corrections to e+e- event shapes.
Structure functions and energy dissipation dependence on Reynolds numberJul 04 2001The dependence of the statistics of energy dissipation on the Reynolds number is investigated in an experimental jet flow. In a range of about one decade of $Re_{\lambda}$ (from about 200 to 2000) the adimensional mean energy dissipation is found to be ... More
The Landau electron problem on a cylinderMay 20 2003Aug 12 2003We consider the quantum mechanics of an electron confined to move on an infinite cylinder in the presence of a uniform radial magnetic field. This problem is in certain ways very similar to the corresponding problem on the infinite plane. Unlike the plane ... More
Barrier crossing to the small Holstein polaron regimeAug 15 2008We investigate the dimensionality effects of the Holstein polaron from the fully quantum regime, where the crossover between large and small polaron solutions is known to be continuous in all dimensions, into the limit described by the semiclassical Discrete ... More
Wigner crystal phases in bilayer grapheneFeb 08 2016It is generally believed that a Wigner Crystal in single layer graphene can not form because the magnitudes of the Coulomb interaction and the kinetic energy scale similarly with decreasing electron density. However, this scaling argument does not hold ... More
Density Fluctuation Mediated SuperconductivitySep 24 2003We conpare predictions of the mean-field theory of supercnductivity for metallic systems on the border of a density instability for cubic and tetragonal lattices. The calculations are based on a parametrisation of an effective interaction arising from ... More
Reconstructions of the Strong Gravitational Lenses MS 2137 and MS 1455 Using a Two-Stage Inversion AlgorithmMay 19 1999We propose a new, two-stage algorithm for inverting strong gravitational lenses. The key to the algorithm is decoupling the effects of lens magnification and intrinsic structure in the background source in the appearance of lensed arcs. First, the distribution ... More
Isotropic Observers and the Inflationary Backreaction ProblemAug 05 2011Apr 27 2012In an inflationary regime driven by a free massive inflaton we derive within a genuinely gauge invariant approach the backreaction effects due to long wavelength scalar fluctuations on the effective Hubble factor and equation of state with respect to ... More
Classification of k-netsJan 29 2016A finite \emph{$k$-net} of order $n$ is an incidence structure consisting of $k\ge 3$ pairwise disjoint classes of lines, each of size $n$, such that every point incident with two lines from distinct classes is incident with exactly one line from each ... More
Generalisations of the Laplace-Runge-Lenz vectorMar 15 2004The characteristic feature of the Kepler Problem is the existence of the so-called Laplace--Runge--Lenz vector which enables a very simple discussion of the properties of the orbit for the problem. It is found that there are many classes of problems, ... More
Magnetically mediated superconductivity: Crossover from cubic to tetragonal latticeJul 23 2002We compare predictions of the mean-field theory of superconductivity for nearly antiferromagnetic and nearly ferromagnetic metals for cubic and tetragonal lattices. The calculations are based on the parametrization of an effective interaction arising ... More
Monte Carlo study of the phase transition in the Critical behavior of the Ising model with shearOct 16 2009The critical behavior of the Ising model with non-conserved dynamics and an external shear profile is analyzed by studying its dynamical evolution in the short time regime. Starting from high temperature disordered configurations (FDC), the critical temperature ... More