Results for "P. C. Cheng"

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Wall Crossing, Discrete Attractor Flow and Borcherds AlgebraJun 16 2008Oct 07 2008The appearance of a generalized (or Borcherds-) Kac-Moody algebra in the spectrum of BPS dyons in N=4, d=4 string theory is elucidated. From the low-energy supergravity analysis, we identify its root lattice as the lattice of the T-duality invariants ... More
Uniaxial Phase Transition in Si : Ab initio CalculationsMay 29 2002Based on a previously proposed thermodynamic analysis, we study the relative stabilities of five Si phases under uniaxial compression using ab initio methods. The five phases are diamond, beta-tin, sh, sc, and hcp structures. The possible phase-transition ... More
Hole doped Dirac states in silicene by biaxial tensile strainOct 28 2013Nov 11 2013The effects of biaxial tensile strain on the structure, electronic states, and mechanical properties of silicene are studied by ab-initio calculations. Our results show that up to 5% strain the Dirac cone remains essentially at the Fermi level, while ... More
Gamma-ray properties of globular clusters and the "fundamental planes"Nov 04 2011We report on the discovery of gamma-ray emission from several globular clusters (GCs), including Terzan 5, the second known gamma-ray GCs. By now, more than a dozen GCs are known to emit gamma-rays of energies above 100 MeV, thus enabling us to carry ... More
On the Performance and Convergence of Distributed Stream Processing via Approximate Fault ToleranceNov 12 2018Nov 17 2018Fault tolerance is critical for distributed stream processing systems, yet achieving error-free fault tolerance often incurs substantial performance overhead. We present AF-Stream, a distributed stream processing system that addresses the trade-off between ... More
Resistivity measurements unveil microscopic properties of CrAsDec 24 2018We report resistivity measurements of a CrAs single crystal in a wide temperature range, with the specific aim to assess the applicability of the Bloch-Gruneisen formula for electron-phonon resistivity. We find that the resistance reaches a residual value ... More
A fitting formula for the merger timescale of galaxies in hierarchical clusteringJul 18 2007Nov 30 2007We study galaxy mergers using a high-resolution cosmological hydro/N-body simulation with star formation, and compare the measured merger timescales with theoretical predictions based on the Chandrasekhar formula. In contrast to Navarro et al., our numerical ... More
Effects of cobalt doping and three-dimensionality in $BaFe_2As_2$Apr 08 2009Jul 21 2009We investigate the dual roles of a cobalt impurity in the Ba-122 ferropnictide superconductor in the state with coexisting collinear spin density wave (SDW) order as a dopant and as a scattering center, using first principles electronic structure methods. ... More
High-Energy Emission of the First Millisecond PulsarMay 09 2014We report on X-ray and gamma-ray observations of the millisecond pulsar B1937+21 taken with the Chandra X-ray Observatory, XMM-Newton, and the Fermi Large Area Telescope. The pulsar X-ray emission shows a purely non-thermal spectrum with a hard photon ... More
K3 Surfaces, N=4 Dyons, and the Mathieu Group M24May 28 2010Jun 03 2010A close relationship between K3 surfaces and the Mathieu groups has been established in the last century. Furthermore, it has been observed recently that the elliptic genus of K3 has a natural interpretation in terms of the dimensions of representations ... More
The Spectra of Supersymmetric States in String TheoryJul 19 2008In this thesis we study the spectra of supersymmetric states in string theory compactifications with eight and sixteen supercharges, with special focus placed on the quantum states of black holes and the phenomenon of wall-crossing in these theories. ... More
More Bubbling SolutionsNov 15 2006Mar 19 2007In this note we construct families of asymptotically flat, smooth, horizonless solutions with a large number of non-trivial two-cycles (bubbles) of N=1 five-dimensional supergravity with an arbitrary number of vector multiplets, which may or may not have ... More
A non-thermal pulsed X-ray emission of AR~ScorpiiDec 18 2017We report the analysis result of UV/X-ray emission from AR~Scorpii, which is an intermediate polar (IP) composed of a magnetic white dwarf and a M-type star, with the XMM-Newton data. The X-ray/UV emission clearly shows a large variation over the orbit, ... More
Early Re-brightenings in GRB Afterglows as Signatures of Low-to-High Density BoundaryApr 01 2005The association of long gamma-ray bursts (GRBs) with star forming regions and the idea of massive stars as progenitors of GRBs are widely accepted. Because of their short lifetimes, it is very likely that massive stars are still embedded in dense molecular ... More
Spin-orbit-coupled dipolar Bose-Einstein condensatesOct 04 2011Jun 08 2012We propose an experimental scheme to create spin-orbit coupling in spin-3 Cr atoms using Raman processes. Employing linear Zeeman effect and optical Stark shift, two spin states within the ground electronic manifold are selected, which results in a pseudo-spin-1/2 ... More
Curvature effect on the interaction between folded graphitic surface and silver clustersAug 12 2008Evidence of curvature effects on the interaction and binding of silver clusters on folded graphitic surfaces has been shown from both experiment and theory. Density Functional Theory (DFT) calculations within the local density and generalized gradient ... More
Non-diffusive spin dynamics in a two-dimensional electron gasOct 03 2006We describe measurements of spin dynamics in the two-dimensional electron gas in GaAs/GaAlAs quantum wells. Optical techniques, including transient spin-grating spectroscopy, are used to probe the relaxation rates of spin polarization waves in the wavevector ... More
Superconducting Vortex with Antiferromagnetic CoreApr 06 1997Jun 27 1997We show that a superconducting vortex in underdoped high T_c superconductors could have an antiferromagnetic core. This type of vortex configuration arises as a topological solution in the recently constructed SO(5) nonlinear sigma model and in Ginzburg-Landau ... More
Flavor symmetry breaking and scaling for improved staggered actions in quenched QCDDec 28 2006We present a study of the flavor symmetry breaking in the pion spectrum for various improved staggered fermion actions. To study the effects of link fattening and tadpole improvement, we use three different variants of the p4 action - p4fat3, p4fat7, ... More
Entropy Production of Open Quantum System in Multi-Bath EnvironmentJul 08 2014We study the entropy production of an open quantum system surrounded by a complex environment consisting of several heat baths at different temperatures. The detailed balance is elaborated in view of the distinguishable channels provided by the couplings ... More
Three-body systems with attractive 1/r potentialsDec 22 2005We have used the hyperspherical adiabatic representation to describe the system of three identical bosons in an spin stretched state interacting by an attractive 1/r potential. A proposal has been made how such a system might be realized experimentally ... More
Photometric properties and luminosity function of nearby massive early-type galaxiesMay 02 2013Jun 07 2013We perform photometric analyses for a bright early-type galaxy (ETG) sample with 2949 galaxies ($M_{\rm r}<-22.5$ mag) in the redshift range of 0.05 to 0.15, drawn from the SDSS DR7 with morphological classification from Galaxy Zoo 1. We measure the Petrosian ... More
Generalised Umbral MoonshineAug 28 2016Mar 02 2019Umbral moonshine describes an unexpected relation between 23 finite groups arising from lattice symmetries and special mock modular forms. It includes the Mathieu moonshine as a special case and can itself be viewed as an example of the more general moonshine ... More
Doppler broadening thermometry based on cavity ring-down spectroscopyFeb 05 2015Jul 22 2015A Doppler broadening thermometry (DBT) instrument is built based on cavity ring-down spectroscopy (CRDS) for precise determination of the Boltzmann constant. Compared with conventional direct absorption methods, the high-sensitivity of CRDS allows to ... More
Gamma-ray emission from the globular clusters Liller 1, M80, NGC 6139, NGC 6541, NGC 6624, and NGC 6752Jan 21 2011Globular clusters (GCs) are emerging as a new class of gamma-ray emitters, thanks to the data obtained from the Fermi Gamma-ray Space Telescope. By now, eight GCs are known to emit gamma-rays at energies >100~MeV. Based on the stellar encounter rate of ... More
Unification of bulk and interface electroresistive switching in oxide systemsMay 20 2008Jun 01 2008We demonstrate that the physical mechanism behind electroresistive switching in oxide Schottky systems is electroformation, as in insulating oxides. Negative resistance shown by the hysteretic current-voltage curves proves that impact ionization is at ... More
High-energy emissions from the gamma-ray binary LS 5039Jun 24 2014We study mechanisms of multi-wavelength emissions (X-ray, GeV and TeV gamma-rays) from the gamma-ray binary LS~5039. This paper is composed of two parts. In the first part, we report on results of observational analysis using four year data of \fermi\ ... More
Measurement of a Sign-Changing Two-Gap Superconducting Phase in Electron-Doped Ba(Fe_{1-x}Co_x)_2As_2 Single Crystals using Scanning Tunneling SpectroscopyJul 28 2010Jan 30 2011Scanning tunneling spectroscopic studies of $Ba(Fe_{1-x}Co_x)_2As_2$ (x = 0.06, 0.12) single crystals reveal direct evidence for predominantly two-gap superconductivity. These gaps decrease with increasing temperature and vanish above the superconducting ... More
Modulation of pairing interaction in Bi$_2$Sr$_2$CaCu$_2$O$_{8+δ}$ by an O dopant: a density functional theory studyJun 10 2010Sep 03 2010Scanning tunneling spectroscopy measurements on the high temperature superconductor Bi$_2$Sr$_2$CaCu$_2$O$_{8+\delta}$ have reported an enhanced spectral gap in the neighborhood of O dopant atoms. We calculate, within density functional theory (DFT), ... More
The radiative corrections of the triangular anomalyMar 06 1996Dec 13 1996We calculate the triangular anomaly in the next order in the Abelian-Higgs theory with an appropriate number of families of chiral fermions and with Yukawa couplings. The calculation is performed with the method of subtraction aided by the Ward- Takahashi ... More
How to renormalize a quantum gauge field theory with chiral fermionsMar 06 1996Mar 06 1996We propose using the method of subtraction to renormalize quantum gauge theories with chiral fermions and with spontaneous symmetry breaking. The Ward-Takahashi identities derived from the BRST invariance in these theories are complex and rich in content. ... More
On a conjecture of Braverman and KazhdanFeb 18 2016In this paper a proof of Conjecture 9.12 of Braverman and Kazhdan in their article "gamma-functions of representations and lifting" on the acyclicity of their l-adic gamma-sheaves over certain affine spaces is given for GL(n).
Baryon Number, Strangeness and Electric Charge Fluctuations in QCD at High TemperatureNov 06 2008May 04 2009We analyze baryon number, strangeness and electric charge fluctuations as well as their correlations in QCD at high temperature. We present results obtained from lattice calculations performed with an improved staggered fermion action (p4-action) at two ... More
Meson propagators in spontaneously broken gauge theoriesJul 09 2001Contrary to common belief, the longitudinal vector meson and scalar meson propagators have very different forms in spontaneously broken gauge theories. We choose the Abelian-Higgs model as an example and show that the longitudinal vector meson and scalar ... More
How to treat $γ_5$Aug 09 1996Feb 25 1997We present a method to perform renormalized perturbation calculation in gauge theories with chiral fermions. We find it proper to focus directly on the Ward-Takahashi identities, relegating dimensional regularization into a supplementary and secondary ... More
The Standard Model in the Alpha gauge is not renormalizableJan 27 1999Jan 27 1999We study the Ward-Takahashi identities in the standard model with the gauge fixing terms given by (1.1) and (1.2). We find that the isolated singularities of the propagators for the unphysical particles are poles of even order, not the simple poles people ... More
Local Density of States and Angle-Resolved Photoemission Spectral Function of an Inhomogeneous D-wave SuperconductorAug 15 2005Nanoscale inhomogeneity seems to be a central feature of the d-wave superconductivity in the cuprates. Such a feature can strongly affect the local density of states (LDOS) and the spectral weight functions. Within the Bogoliubov-de Gennes formalism we ... More
Nonlinear magneto-optic effects in doped graphene and gapped graphene: a perturbative treatmentNov 13 2017Mar 02 2018The nonlinear magneto-optic responses are investigated for gapped graphene and doped graphene in a perpendicular magnetic field. The electronic states are described by Landau levels, and the electron dynamics in an optical field is obtained by solving ... More
Enhancement of Jc by doping silver in grain boundaries of YBa2Cu3Oy polycrystals with solid-state diffusion methodFeb 06 2003Grain boundaries (GBs) of YBa2Cu3Oy (YBCO) are preferentially doped with Ag by the solid-state diffusion method. The distribution of Ag is highly localized in the GB. As a result of the Ag doping, the Jc-H behavior of YBCO textured polycrystalline samples ... More
Spin relaxation in $n$-type ZnO quantum wellsAug 05 2009Sep 14 2009We perform an investigation on the spin relaxation for $n$-type ZnO (0001) quantum wells by numerically solving the kinetic spin Bloch equations with all the relevant scattering explicitly included. We show the temperature and electron density dependence ... More
Bit Flipping Moment Balancing Schemes for Insertion, Deletion and Substitution Error CorrectionJan 23 2019In this paper, two moment balancing schemes, namely a variable index scheme and a fixed index scheme, for either single insertion/deletion error correction or multiple substitution error correction are introduced for coded sequences originally developed ... More
Physical masses and the vacuum expectation value of the Higgs fieldMar 07 1996By using the Ward-Takahashi identities in the Landau gauge, we derive exact relations between particle masses and the vacuum expectation value of the Higgs field in the Abelian gauge field theory with a Higgs meson.
Is the Standard Model Renormalizable?Feb 26 1999In this paper, we study the renormalizability of the Standard Model in the Landau gauge. On the basis of the Ward-Takahashi identities, we derive exact expressions for the physical masses of the W and Z as well as the renormalized coupling constants in ... More
Nonperturbative model for optical response under intense periodic fields with application to graphene in a strong perpendicular magnetic fieldDec 26 2017Mar 02 2018Graphene exhibits extremely strong optical nonlinearity when a strong perpendicular magnetic field is applied, the response current shows strong field dependence even for moderate light intensity, and the perturbation theory fails. We nonperturbatively ... More
Quantum Decoherence of Charge Qubit coupled to Nonlinear Nanomechanical ResonatorApr 27 2013When the nonlinearity of nanomechanical resonator is not negligible, the quantum decoherence of charge qubit is studied analytically. Using nonlinear Jaynes-Cummings model, one explores the possibility of being quantum data bus for nonlinear nanomechanical ... More
Parsec-scale radio structure of 14 Fanaroff-Riley type 0 radio galaxiesJul 06 2018Recently a population of compact radio galaxies were classified as Fanaroff-Riley type 0 radio galaxies (FR 0s). The physical nature of FR 0s and the connection with the classical FR I and II galaxies are not currently well understood. Here, we report ... More
Analytical smoothing effect of solution for the boussinesq equationsFeb 22 2017In this paper, we study the analytical smoothing effect of Cauchy problem for the incompressible Boussinesq equations. Precisely, we use the Fourier method to prove that the Sobolev H 1-solution to the incompressible Boussinesq equations in periodic domain ... More
Non-Divergence of Unipotent Flows on Quotients of Rank One Semisimple GroupsAug 12 2014Let $G$ be a semisimple Lie group of rank $1$ and $\Gamma$ be a torsion free discrete subgroup of $G$. We show that in $G/\Gamma$, given $\epsilon>0$, any trajectory of a unipotent flow remains in the set of points with injectivity radius larger than ... More
Mode change of a gamma-ray pulsar, PSR J2021+4026Jun 01 2017Jun 11 2017A glitch of a pulsar is known as a sudden increase in the spin frequency and spin-down rate (frequency time derivative), and it can be caused by a sudden rel\ ease of the stress built up in the solid crust of the star or pinned vortices in the superfluid ... More
Equation of State for physical quark massesNov 11 2009Mar 16 2010We calculate the QCD equation of state for temperatures corresponding to the transition region with physical mass values for two degenerate light quark flavors and a strange quark using an improved staggered fermion action (p4-action) on lattices with ... More
The existence of solutions of 2-dimensional incompressible Navier-Stokes equations with surface tension in an optimal Sobolev spaceJul 14 2013We establish the existence of a solution to the Navier-Stokes equations on a moving domain with surface tension in an optimal Sobolev space for the case of two space dimension. No compatibility conditions are required to guarantee the existence of a solution. ... More
The Cross-Correlation between Galaxies and Groups: Probing the Galaxy Distribution in and around Dark Matter HaloesApr 21 2005Jun 27 2005We determine the cross-correlation function between galaxies and galaxy groups, using both the Two-Degree Field Galaxy Redshift Survey (2dFGRS) and the Sloan Digital Sky Survey (SDSS). We study the cross-correlation as a function of group mass, and as ... More
The Phase-Space Parameters of Brightest Halo GalaxiesFeb 23 2005Mar 01 2005The brightest galaxy in a dark matter halo is expected to reside at rest at the center of the halo. In this paper we test this `Central Galaxy Paradigm' using group catalogues extracted from the 2dFGRS and the SDSS. For each group we compute a parameter, ... More
A Circular White-Light Flare with Impulsive and Gradual White-Light KernelsDec 20 2017White-light flares are the flares with emissions visible in the optical continuum. They are thought to be rare and pose the most stringent requirements in energy transport and heating in the lower atmosphere. Here we present a nearly circular white-light ... More
A Large Effective Phonon Magnetic Moment in a Dirac SemimetalMay 01 2019We have investigated the low frequency terahertz response of the Dirac semimetal Cd$_3$As$_2$ concentrating on its phonon dynamics and their response to magnetic field. Due to the very small effective mass in these materials, we observed a very prominent ... More
Magnetic microscopy and simulation of strain-mediated control of magnetization in Ni/PMN-PT nanostructuresOct 03 2016Strain-mediated thin film multiferroics comprising piezoelectric/ferromagnetic heterostructures enable the electrical manipulation of magnetization with much greater efficiency than other methods; however, the investigation of nanostructures fabricated ... More
Rapid X-ray variations of the Geminga pulsar wind nebulaAug 14 2017A recent study by Posselt et al. (2017) reported the deepest X-ray investigation of the Geminga pulsar wind nebula (PWN) by using \emph{Chandra X-ray Observatory}. In comparison with previous studies of this system, a number of new findings have been ... More
Discovery of GeV gamma-ray emission from PSR B1259-63/LS 2883Mar 16 2011Jun 02 2011The binary system PSR B1259-63/LS 2883 consists of a 47.8 ms radio pulsar that orbits the companion Be star with a period of 3.4 years in a highly eccentric orbit. The system is well sampled in radio, X-rays, and TeV gamma-rays, and shows orbital-phase-dependent ... More
Electrostatic Force Microscopy on Oriented Graphite Surfaces: Where Insulating and Conducting Behaviors CoexistApr 11 2006We present measurements of the electric potential fluctuations on the surface of highly oriented pyrolytic graphite using electrostatic force and atomic force microscopy. Micrometric domain-like potential distributions are observed even when the sample ... More
Spatial and kinematic alignments between central and satellite halosJun 02 2007Dec 18 2007Based on a cosmological N-body simulation we analyze spatial and kinematic alignments of satellite halos within six times the virial radius of group size host halos (Rvir). We measure three different types of spatial alignment: halo alignment between ... More
Anomalous Meissner effect in pnictide superconductorsOct 22 2010The Meissner effect has been studied in Ba(Fe0.926Co0.074)2As2 and Ba0.6K0.4Fe2As2 single crystals and compared to well known, type-II superconductors LuNi2B2C and V3Si. Whereas flux penetration is mostly determined by the bulk pinning (and, perhaps, ... More
Penetration of cosmic rays into dense molecular clouds: role of diffuse envelopeFeb 07 2018A flux of cosmic rays (CRs) propagating through a diffuse ionized gas can excite MHD waves, thus generating magnetic disturbances. We propose a generic model of CR penetration into molecular clouds through their diffuse envelopes, and identify the leading ... More
In-memory computing on a photonic platformJan 18 2018Collocated data processing and storage are the norm in biological systems. Indeed, the von Neumann computing architecture, that physically and temporally separates processing and memory, was born more of pragmatism based on available technology. As our ... More
Frictional Drag Between Coupled 2D Hole Gases in GaAs/AlGaAs HeterostructuresApr 15 1999We report on the first measurements of the drag effect between coupled 2D-hole gases. We investigate the coupling by changing the carrier densities in the quantum wells, the widths of the barriers between the gases and the perpendicular magnetic field. ... More
Improved Irreversibility Behaviour and Critical Current Density in MgB2-Diamond NanocompositesFeb 18 2003MgB2-diamond nanocomposite superconductors have been synthesized by addition of nano-diamond powder. Microstructural analysis shows that the nanocomposite superconductor consists of tightly-packed MgB2 nano-grains (~50-100 nm) with highly-dispersed and ... More
An experimental study on $Γ$(2) modular symmetry in the quantum Hall system with a small spin-splittingSep 13 2006Dec 26 2006Magnetic-field-induced phase transitions were studied with a two-dimensional electron AlGaAs/GaAs system. The temperature-driven flow diagram shows the features of the $\Gamma$(2) modular symmetry, which includes distorted flowlines and shiftted critical ... More
Studying the SGR 1806-20/Cl* 1806-20 region using the \emph{Fermi} Large Area TelescopeJun 06 2016The region around SGR 1806-20 and its host stellar cluster Cl* 1806-20 is a potentially important site of particle acceleration. The soft $\gamma-$ray repeater and Cl* 1806-20, which also contains several very massive stars including a luminous blue variable ... More
Anomalous Scaling and Refined Similarity of an Active Scalar in a Model of Homogeneous Turbulent ConvectionAug 02 2007Nov 07 2007Anomalous scaling in the statistics of an active scalar in homogeneous turbulent convection is studied using a dynamical shell model. We extend refined similarity ideas for homogeneous and isotropic turbulence to homogeneous turbulent convection and attribute ... More
Modeling the Heating and Cooling of WZ Sagittae following the July 2001 OutburstOct 30 2003FUSE and HST/STIS spectra of the dwarf nova WZ Sge, obtained during and following the early superoutburst of July 2001 over a time span of 20 months, monitor changes in the components of the system during its different phases. The synthetic spectral fits ... More
A Two-ribbon White-light Flare Associated with a Failed Solar Eruption Observed by ONSET, SDO, and IRISJul 08 2015Two-ribbon brightenings are one of the most remarkable characteristics of an eruptive solar flare and are often used for predicting the occurrence of coronal mass ejections (CMEs). Nevertheless, it was called in question recently whether all two-ribbon ... More
Pathways-driven Sparse Regression Identifies Pathways and Genes Associated with High-density Lipoprotein Cholesterol in Two Asian CohortsFeb 23 2013Standard approaches to analysing data in genome-wide association studies (GWAS) ignore any potential functional relationships between genetic markers. In contrast gene pathways analysis uses prior information on functional structure within the genome ... More
The Alignment between Satellites and Central Galaxies: Theory vs. ObservationsJan 05 2007Apr 24 2007Recent studies have shown that the distribution of satellite galaxies is preferentially aligned with the major axis of their central galaxy. The strength of this alignment has been found to depend strongly on the colours of the satellite and central galaxies, ... More
All-electron self-consistent GW in the Matsubara-time domain: implementation and benchmarks of semiconductors and insulatorsFeb 06 2016The GW approximation is a well-known method to improve electronic structure predictions calculated within density functional theory. In this work, we have implemented a computationally efficient GW approach that calculates central properties within the ... More
X-ray Census of Millisecond Pulsars in the Galactic fieldJul 17 2018We have conducted a systematic survey for the X-ray properties of millisecond pulsars (MSPs). Currently, there are 47 MSPs with confirmed X-ray detections. We have also placed the upper limits for the X-ray emission from the other 36 MSPs by using the ... More
Gamma-ray Emission of the Kes 73/1E 1841-045 Region Observed with the Fermi Large Area TelescopeJan 31 2017Feb 21 2017The supernova remnant Kes 73 and/or the magnetar 1E 1841-045 at its center can deposit a large amount of energy to the surroundings and is potentially responsible for particle acceleration. Using the data taken with the Fermi Large Area Telescope (LAT), ... More
Discovery of an ultracompact gamma-ray millisecond pulsar binary candidateAug 21 2014Sep 21 2014We report multi-wavelength observations of the unidentified Fermi object 2FGL J1653.6-0159. With the help of high-resolution X-ray observation, we have identified an X-ray and optical counterpart of 2FGL J1653.6-0159. The source exhibits a periodic modulation ... More
Anomalous quantum-critical spin dynamics in YFe2Al10Jan 11 2018We report results of a muon spin relaxation ($\mu$SR) study of YFe$_2$Al$_{10}$, a quasi-2D nearly-ferromagnetic metal in which unconventional quantum critical behavior is observed. No static Fe$^{2+}$ magnetism, with or without long-range order, is found ... More
Anomalous quantum-critical spin dynamics in YFe2Al10Jan 11 2018Feb 14 2018We report results of a muon spin relaxation ($\mu$SR) study of YFe$_2$Al$_{10}$, a quasi-2D nearly-ferromagnetic metal in which unconventional quantum critical behavior is observed. No static Fe$^{2+}$ magnetism, with or without long-range order, is found ... More
Fermi-LAT Detection of Pulsed Gamma-rays Above 50 GeV from the Vela PulsarOct 20 2014Oct 21 2014The First \fermi-LAT Catalog of Sources Above 10 GeV reported evidence of pulsed emission above 25 GeV from 12 pulsars, including the Vela pulsar, which showed evidence of pulsation at $>37$ GeV energy bands. Using 62 months of \fermi-LAT data, we analyzed ... More
Exploring the X-ray and gamma-ray properties of the redback millisecond pulsar PSR J1723-2837Nov 01 2013Dec 24 2013We have investigated the X-ray and $\gamma$-ray properties of the redback millisecond pulsar PSR J1723-2837 with XMM-Newton, Chandra and Fermi. We have discovered the X-ray orbital modulation of this binary system with the minimum that coincides with ... More
Localization in the non-analytic quantum kicked systemsJul 09 2004Numerical investigations on non-analytic quantum kicked systems are presented. A new type of localization - power-law localization is found to be universal in the nonanalytic systems. With increasing the perturbation strength, a transition from perturbative ... More
Searches for millisecond pulsar candidates among the unidentified Fermi objectsJul 09 2015Here we report the results of searching millisecond pulsar (MSP) candidates from the Fermi LAT second source catalog (2FGL). Seven unassociated $\gamma-$ray sources in this catalog are identified as promising MSP candidates based on their $\gamma$-ray ... More
The birth of radio millisecond pulsars and their high-energy signatureDec 16 2014Millisecond pulsars (MSPs) are thought to born in low-mass X-ray binaries when the neutron star has gained enough angular momentum from the accreting materials of its companion star. It is generally believed that a radio MSP is born when the neutron star ... More
High-Energy emissions from the Pulsar/Be binary system PSR J2032+4127/MT91 213Feb 15 2017PSR J2032+4127 is a radio-loud gamma-ray-emitting pulsar; it is orbiting around a high-mass Be type star with a very long orbital period of 25-50years, and is approaching periastron, which will occur in late 2017/early 2018. This system comprises with ... More
CO (7-6), [CI] 370 micron and [NII] 205 micron Line Emission of the QSO BRI 1335-0417 at Redshift 4.407Jul 16 2018We present the results from our Atacama Large Millimeter/submillimeter Array (ALMA) imaging observations of the CO (7-6), [CI] 370 um (hereafter [CI]) and [NII] 205 um (hereafter [NI]I) lines and their underlying continuum emission of BRI 1335-0417, an ... More
High-Tc superconductivity up to 55 K under high pressure in the heavily electron doped Lix(NH3)yFe2Se2 single crystalSep 25 2017We report a high-pressure study on the heavily electron doped Lix(NH3)yFe2Se2 single crystal by using the cubic anvil cell apparatus. The superconducting transition temperature Tc = 44 K at ambient pressure is first suppressed to below 20 K upon increasing ... More
The X-ray modulation of PSR J2032+4127/MT91 213 during the Periastron Passage in 2017Mar 18 2018We present the Neil Gehrels Swift Observatory (Swift), Fermi Large Area Telescope (Fermi-LAT), and Karl G. Jansky Very Large Array (VLA) observations of the gamma-ray binary PSR J2032+4127/MT91 213, of which the periastron passage has just occurred in ... More
Extreme Ultraviolet Imaging of Three-dimensional Magnetic Reconnection in a Solar EruptionJun 27 2015Magnetic reconnection, a change of magnetic field connectivity, is a fundamental physical process in which magnetic energy is released explosively. It is responsible for various eruptive phenomena in the universe. However, this process is difficult to ... More
Exploring the intrabinary shock from the redback millisecond pulsar PSR J2129-0429Feb 13 2015We have investigated the intrabinary shock emission from the redback millisecond pulsar PSR J2129-0429 with XMM-Newton and Fermi. Orbital modulation in X-ray and UV can be clearly seen. Its X-ray modulation has a double-peak structure with a dip in between. ... More
Observing two dark accelerators around the Galactic Centre with Fermi Large Area TelescopeJan 25 2016We report the results from a detailed $\gamma-$ray investigation in the field of two "dark accelerators", HESS J1745-303 and HESS J1741-302, with $6.9$ years of data obtained by the Fermi Large Area Telescope. For HESS J1745-303, we found that its MeV-GeV ... 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
Non-perturbative QCD spin studiesNov 09 1998A whole class of non-perturbative QCD studies, e.g. the instanton models, chiral quark models, etc. indicates that the effective degrees of freedom for the physics in the low Q^(2) < 1 GeV^(2) region could be the constituent quarks (CQs) and internal ... More
The Proton Spin and Flavor Structure in the Chiral Quark ModelSep 09 1997After a pedagogical review of the simple constituent quark model and deep inelastic sum rules, we describe how a quark sea as produced by the emission of internal Goldstone bosons by the valence quarks can account for the observed features of proton spin ... More
Antiquark Polarization inside the Proton is SmallOct 05 1995Oct 08 1995Quark contributions to the proton spin as deduced from polarized DIS of leptons off a nucleon target, and the octet baryon magnetic moments, can be used to deduce the antiquark polarizations $\Delta_{\overline{q}}$ inside the proton. In this way, the ... More
Sunspot Rotation as a Driver of Major Solar Eruptions in NOAA Active Region 12158Jul 13 2016We studied the developing conditions of sigmoid structure under the influence of magnetic non-potential characteristics of a rotating sunspot in the active region (AR) 12158. Vector magnetic field measurements from Helioseismic Magnetic Imager and coronal ... More
A Geometric Derivation of the Dyon Wall-Crossing GroupJan 13 2009Recently, using supergravity analysis, a hyperbolic reflection group was found to underlie the structure of wall-crossing, or the discontinuous moduli dependence of the supersymmetric index due to the presence of walls of marginal stability, of the BPS ... More
Dying Dyons Don't CountJun 17 2007Oct 31 2008The dyonic 1/4-BPS states in 4D string theory with N=4 spacetime supersymmetry are counted by a Siegel modular form. The pole structure of the modular form leads to a contour dependence in the counting formula obscuring its duality invariance. We exhibit ... More
How Do the Open Source Communities Address Usability and UX Issues? An Exploratory StudyFeb 20 2019Usability and user experience (UX) issues are often not well emphasized and addressed in open source software (OSS) development. There is an imperative need for supporting OSS communities to collaboratively identify, understand, and fix UX design issues ... More
Imaging and Spectroscopic Diagnostics on the Formation of Two Magnetic Flux Ropes Revealed by SDO/AIA and IRISFeb 27 2015Helical magnetic flux rope (MFR) is a fundamental structure of corona mass ejections (CMEs) and has been discovered recently to exist as a sigmoidal channel structure prior to its eruption in the extreme ultraviolet (EUV) high temperature passbands of ... More
Solvability and regularity for an elliptic system prescribing the curl, divergence, and partial trace of a vector field on Sobolev-class domainsAug 11 2014Sep 09 2015We provide a self-contained proof of the solvability and regularity of a Hodge-type elliptic system, wherein the divergence and curl of a vector field are prescribed in an open, bounded, Sobolev-class domain, and either the normal component or the tangential ... More