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Results for "M. Gu"

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New Benchmark of X-ray Line Emission Models of Fe XVIIMay 05 2009We review the accuracy of existing \ion{Fe}{17} X-ray line emission models by comparing them with an extensive analysis of \textit{Chandra} high energy transmission grating (HETG) observations of stellar coronae. We find significant discrepancies between ... More
Connectivity, toughness, spanning trees of bounded degree, and the spectrum of regular graphsFeb 18 2016In this paper, we present some new results describing connections between the spectrum of a regular graph and its generalized connectivity, toughness, and the existence of spanning trees with bounded degree.
Universal condition for critical percolation thresholds of kagome-like latticesDec 01 2008Jan 13 2009Lattices that can be represented in a kagome-like form are shown to satisfy a universal percolation criticality condition, expressed as a relation between P_3, the probability that all three vertices in the triangle connect, and P_0, the probability that ... More
Carbon Nanotube-based Super Nanotube: Tailorable Thermal Conductivity at Three-dimensionalMay 21 2015The advancements of nanomaterials or nanostructures have enabled the possibility of fabricating multifunctional materials that hold great promises in engineering applications. The carbon nanotube (CNT)-based nanostructure is one representative building ... More
Scaling Study of the Metal-Insulator Transition in one-Dimensional Fermion SystemsMar 20 2003We consider the Ising phase of the antiferromagnetic XXZ Heisenberg chain on a finite-size lattice with N sites.We compute the large $N$ behavior of the spin stiffness, obtaining the correlation length \xi. We use our results to discuss the scaling behavior ... More
Robust charge stripe order under high electric fields in Nd1.67Sr0.33NiO4Oct 05 2006The influence of high electric fields on the charge stripe order in Nd1.67Sr0.33NiO4 was studied by means of simultaneous hard x-ray diffraction and electrical transport experiments. Direct measurements of the charge stripe satellite peaks in zero and ... More
Fabrication of Asymmetric Electrode Pairs with Nanometer Separation Made of Two Distinct MetalsSep 15 2003We report a simple and reproducible method to fabricate two metallic electrodes made of different metals with a nanometer-sized gap. These electrodes are fabricated by defining a pair of gold electrodes lithographically and electrodepositing a second ... More
The morphology and temperature dependent tensile properties of diamond nanothreadsMar 17 2018The ultrathin one-dimensional sp3 diamond nanothreads (NTHs), as successfully synthesised recently, have greatly augmented the interests from the carbon community. In principle, there can exist different stable NTH structures. In this work, we studied ... More
Numerical and Monte Carlo Bethe ansatz method: 1D Heisenberg modelOct 22 2002In this paper we present two new numerical methods for studying thermodynamic quantities of integrable models. As an example of the effectiveness of these two approaches, results from numerical solutions of all sets of Bethe ansatz equations, for small ... More
A reduced complexity numerical method for optimal gate synthesisNov 28 2010Although quantum computers have the potential to efficiently solve certain problems considered difficult by known classical approaches, the design of a quantum circuit remains computationally difficult. It is known that the optimal gate design problem ... More
Inner-shell Absorption Lines of Fe~VI-- Fe~XVI: A Many-body Perturbation Theory ApproachDec 15 2005We provide improved atomic calculation of wavelengths, oscillator strengths, and autoionization rates relevant to the $2\to 3$ inner-shell transitions of Fe~VI--XVI, the so-called Fe~M-shell unresolved transition array (UTA). A second order many-body ... More
Robust charge and magnetic order under electric field and current in the multiferroic LuFe(2)O(4)Jan 20 2010Apr 20 2010We performed elastic neutron scattering measurements on the charge- and magnetically-ordered multiferroic material LuFe(2)O(4). An external electric field along the [001] direction with strength up to 20 kV/cm applied at low temperature (~100 K) does ... More
In-situ electron backscatter diffraction of thermal cycling in a single grain Cu/Sn-3Ag-0.5Cu/Cu solder jointJul 15 2019The heterogeneous evolution of microstructure in a single Cu/SAC305/Cu solder joint is investigated using in-situ thermal cycling combined with electron backscatter diffraction (EBSD). Local deformation due to thermal expansion mismatch results in heterogeneous ... More
Spontaneous symmetry breaking by charge stripes in the high-pressure phase of superconducting La(1.875)Ba(0.125)CuO(4)Sep 29 2009Feb 03 2010In those cases where charge stripe order has been observed in cuprates, the crystal structure is such that the average rotational symmetry of the CuO2 planes is reduced from four-fold to two-fold. As a result, one could argue that the reduced lattice ... More
Charge and Spin Transport in the One-dimensional Hubbard ModelOct 24 2007Nov 20 2007In this paper we study the charge and spin currents transported by the elementary excitations of the one-dimensional Hubbard model. The corresponding current spectra are obtained by both analytic methods and numerical solution of the Bethe-ansatz equations. ... More
Peak Effect of Flux Pinning in Sc5Ir4Si10 SuperconductorsOct 15 2010Magnetic hysteresis loops (MHLs) have been comparatively measured on both textured and single crystalline Sc5Ir4Si10 superconductors. Critical current densities and flux pinning forces are calculated from MHLs by Bean model. Three kinds of peaks of the ... More
Modeling of heterojunction photovoltaic cells based on ZnO nanowires array and earth-abundant cuprous oxide absorbersDec 09 2010Jan 27 2011As a potential solution for low-cost efficient solar cells, radial junctions consisting of ZnO nanowires arrays embedded in Cu2O thin films have been theoretically modeled. Calculations have been performed to explore the geometric dependence of performance ... More
Non-Fermi Liquid Behavior in 3+1 Dimensions with PT Invariant Gauge Field: An Renormalization Group ApproachNov 29 1994We introduce a Hamiltonian coupled between a normal Fermi surface and a polarized Maxwell type gauge field.We adopt a {\it calibrated scaling } approach in order to be consistent with the results obtained at $2+1$ dimensions as well as the Weinberg's ... More
An efficient algorithm for solving elliptic problems on percolation clustersJul 31 2019We present an efficient algorithm to solve elliptic Dirichlet problems defined on the cluster of $\mathbb{Z}^d$ supercritical Bernoulli percolation, as a generalization of the iterative method proposed by S. Armstrong, A. Hannukainen, T. Kuusi and J.-C. ... More
Enumeration of paths and cycles and e-coefficients of incomparability graphsSep 04 2007We prove that the number of Hamiltonian paths on the complement of an acyclic digraph is equal to the number of cycle covers. As an application, we obtain a new expansion of the chromatic symmetric function of incomparability graphs in terms of elementary ... More
Quantum Strategies and Local OperationsFeb 26 2010Mar 14 2012This thesis is divided into two parts. In Part I we introduce a new formalism for quantum strategies, which specify the actions of one party in any multi-party interaction involving the exchange of multiple quantum messages among the parties. This formalism ... More
Short Quantum GamesNov 03 2005In this thesis we introduce quantum refereed games, which are quantum interactive proof systems with two competing provers. We focus on a restriction of this model that we call "short quantum games" and we prove an upper bound and a lower bound on the ... More
A partition of connected graphsMay 09 2005We define an algorithm k which takes a connected graph G on a totally ordered vertex set and returns an increasing tree R (which is not necessarily a subtree of G). We characterize the set of graphs G such that k(G)=R. Because this set has a simple structure ... More
A remark on descent for Coxeter groupsJul 04 2017Jul 06 2017Let $\Gamma$ be a finite Coxeter group with reflection representation $R$. We show that a $\Gamma$-equivariant quasicoherent sheaf on $R$ descends to the quotient space $R//\Gamma$ if it descends to the quotient space $R//\langle s_i\rangle$ for every ... More
On the Cohomology of the Classifying Spaces of Projective Unitary GroupsDec 01 2016Jan 29 2019Let $\mathbf{B}PU_{n}$ be the classifying space of $PU_n$, the projective unitary group of order $n$, for $n>1$. We use the Serre spectral sequence associated to a fiber sequence $\mathbf{B}U_n\rightarrow\mathbf{B}PU_n\rightarrow K(\mathbb{Z},3)$ to determine ... More
Integrable systems from the classical reflection equationMay 21 2014Jun 08 2015We construct integrable Hamiltonian systems on $G/K$, where $G$ is a quasitriangular Poisson Lie group and $K$ is a Lie subgroup arising as the fixed point set of a group automorphism $\sigma$ of $G$ satisfying the classical reflection equation. In the ... More
The evolution of dusty torus covering factor in quasarsJul 04 2013Jul 15 2013We have assembled a large sample of 5996 quasars at redshift 2.0=< z <= 2.4 (high-z) or 0.7=< z <= 1.1 (low-z) from SDSS data release nine and seven quasar catalogs. The spectral energy distribution (SED) of quasars were constructed by collecting WISE, ... More
A Study of Weakly Discontinuous Solutions for Hyperbolic Differential Equations Based on Wavelet Transform MethodsSep 20 2013Dec 25 2013A new way to prove the one-dimensional Cauchy problem's weakly discontinuous solutions for hyperbolic PDEs are on the characteristics is discussed in this paper. To do so, I use wavelet singularity detection methods or WTMM [1] based on two-dimensional ... More
Shrinkability of Decomposition of $S^n$ Having Arbitrarily Small Neighborhoods with ($n-1$)-Sphere FrontiersSep 20 2013Dec 04 2013Let $G$ be a usc decomposition of $S^n$, $H_G$ denote the set of nondegenerate elements and $\pi$ be the natural projection of $S^n$ onto $S^n/G$. Suppose that each point in the decomposition space has arbitrarily small neighborhoods with ($n-1$)-sphere ... More
A Study of Weakly Discontinuous Solutions for Hyperbolic Differential Equations Based on Wavelet Transform MethodsNov 03 2013Dec 04 2013A new approach to prove the one-dimensional Cauchy problem's weakly discontinuous solutions for hyperbolic PDEs are on the characteristics is discussed in this paper. To do so, I use wavelet singularity detection methods or WTMM [1] based on two-dimensional ... More
Set maps, umbral calculus, and the chromatic polynomialJul 03 2005Jul 05 2007Some important properties of the chromatic polynomial also hold for any polynomial set map satisfying p_S(x+y)=\sum_{T\uplus U=S}p_T(x)p_U(y). Using umbral calculus, we give a formula for the expansion of such a set map in terms of any polynomial sequence ... More
Surface effect on the wrinkling of an elastic sheet under tensionOct 27 2013Nov 21 2013Wrinkling of stretched elastic sheets is widely observed, and the scaling relations between the amplitude and wavelength of the wrinkles have been proposed by Cerda and Mahadevan. However, the surface effects should be taken into account when the sheet ... More
Cascading A*: a Parallel Approach to Approximate Heuristic SearchJun 04 2014May 03 2016In this paper, we proposed a new approximate heuristic search algorithm: Cascading A*, which is a two-phrase algorithm combining A* and IDA* by a new concept "envelope ball". The new algorithm CA* is efficient, able to generate approximate solution and ... More
On algebraic surfaces of general type with negative c2Nov 30 2014Dec 08 2014We prove that for any prime number $p\ge 3$, there exists a positive number $\kappa_p$ such that $\chi(\mathcal{O}_X)\ge \kappa_pc_1^2$ holds true for all algebraic surfaces $X$ of general type in characteristic $p$. In particular, $\chi(\mathcal{O}_X)>0$. ... More
Some torsion classes in the Chow ring and cohomology of $BPGL_n$Jan 29 2019Apr 22 2019In the integral cohomology ring of the classifying space of the projective linear group $PGL_n$ (over $\mathbb{C}$), we find a collection of $p$-torsions $y_{p,k}$ of degree $2(p^{k+1}+1)$ for any odd prime divisor $p$ of $n$, and $k\geq 0$. If in addition, ... More
On a measure of distance for quantum strategiesAug 27 2010Mar 14 2012The present paper studies an operator norm that captures the distinguishability of quantum strategies in the same sense that the trace norm captures the distinguishability of quantum states or the diamond norm captures the distinguishability of quantum ... More
A Note on Bounded Biclique Coverings of Complete GraphsNov 09 2015An undirected biclique $K_{a,b}$ is a graph with vertices partitioned into two sets: a set $A$ containing $a$ vertices and a set $B$ containing $b$ vertices such that every vertex in set $A$ is connected to every vertex in set $B$, and such that no two ... More
The Topological Period-Index Problem over 8-Complexes, IIMar 14 2018Jun 04 2019We complete the study of the topological period-index problem over 8 dimensional finite CW complexes started in a preceding paper. More precisely, we determine the sharp upper bound of the index of a topological Brauer class $\alpha\in H^3(X;\mathbb{Z})$, ... More
Neyman's C(α) Test for Unobserved HeterogeneityFeb 01 2013Oct 06 2014A unified framework is proposed for tests of unobserved heterogeneity in parametric statistic models based on Neyman's $C(\alpha)$ approach. Such tests are irregular in the sense that the first order derivative of the log likelihood with respect to the ... More
Spanning rigid subgraph packing and sparse subgraph coveringMay 01 2014Jun 12 2018Rigidity, arising in discrete geometry, is the property of a structure that does not flex. Laman provides a combinatorial characterization of rigid graphs in the Euclidean plane, and thus rigid graphs in the Euclidean plane have applications in graph ... More
Strong Suppression of the Spin Hall Effect in the Spin Glass StateOct 03 2015Nov 09 2015We have measured spin Hall effects in spin glass metals, CuMnBi alloys, with the spin absorption method in the lateral spin valve structure. Far above the spin glass temperature Tg where the magnetic moments of Mn impurities are randomly frozen, the spin ... More
Photocurrent Enhancement of Graphene Photodetectors by Photon Tunneling of Light into Surface PlasmonsOct 13 2016We demonstrate that surface plasmon resonances excited by photon tunneling through an adjacent dielectric medium enhance photocurrent detected by a graphene photodetector. The device is created by overlaying a graphene sheet over an etched gap in a gold ... More
Coherent State Distinguishability in Continuous Variable Quantum CryptographyMar 15 2007We use the probability of error as a measure of distinguishability between two pure and two mixed symmetric coherent states in the context of continuous variable quantum cryptography. We show that the two mixed symmetric coherent states (in which the ... More
Evidence for local moment magnetism in superconducting FeTe0.35Se0.65Dec 10 2010The nature of the magnetic correlations in Fe-based superconductors remains a matter of controversy. To address this issue, we use inelastic neutron scattering to characterize the strength and temperature dependence of low-energy spin fluctuations in ... More
Magnetic field induced enhancement of spin-order peak intensity in La(1.875)Ba(0.125)CuO(4)Oct 22 2008Dec 18 2008We report on neutron-scattering results on the impact of a magnetic field on stripe order in the cuprate La$_{1.875}$Ba$_{0.125}$CuO$_4$. It is found that a 7 T magnetic field applied along the {\it c} axis causes a small but finite enhancement of the ... More
Baryon content and dynamic state of galaxy clusters: XMM-Newton observations of A1095 and A1926Mar 11 2016We have initiated a program to study the baryon content and dynamic state of galaxy clusters. Here we present results primarily from XMM-Newton observations of two optically-selected galaxy clusters, A1095 ($z \simeq 0.210$) and A1926 ($z \simeq 0.136$). ... More
Neutrino masses, leptogenesis and dark matter in hybrid seesawNov 06 2008We suggest a hybrid seesaw model where relatively ``light''right-handed neutrinos give no contribution to the neutrino mass matrix due to a special symmetry. This allows their Yukawa couplings to the standard model particles to be relatively strong, so ... More
Magnetic field control of charge structures in the magnetically disordered phase of the multiferroic LuFe$_2$O$_4$Apr 09 2009Apr 10 2009Using neutron diffraction, we have studied the magnetic field effect on charge structures in the charge-ordered multiferroic material LuFe$_2$O$_4$. An external magnetic field is able to change the magnitude and correlation lengths of the charge valence ... More
Operational resource theory of continuous-variable nonclassicalityApr 26 2018Dec 10 2018Genuinely quantum states of a harmonic oscillator may be distinguished from their classical counterparts by the Glauber-Sudarshan P-representation -- a state lacking a positive P-function is said to be nonclassical. In this paper, we propose a general ... More
Time Reversal Symmetry Breaking in the Fe-Chalcogenide SuperconductorsJul 26 2019The interplay of topology and superconductivity has been studied in the FeTe1-xSex family of Fe-based superconductors using high resolution laser-based photoemission. At the superconducting transition a gap is observed to open at the Dirac point in a ... More
Thermal conductivity of a new carbon nanotube analogue: the diamond nanothreadNov 05 2015Based on the non-equilibrium molecular dynamics simulations, we have studied the thermal conductivities of a novel ultra-thin one-dimensional carbon nanomaterial - diamond nanothread (DNT). Unlike single-wall carbon nanotube (CNT), the existence of the ... More
Antiferromagnetism and chiral d-wave superconductivity from an effective $t-J-D$ model for twisted bilayer grapheneJan 31 2019Starting from the strong-coupling limit of an extended Hubbard model, we develop a spin-fermion theory to study the insulating phase and pairing symmetry of the superconducting phase in twisted bilayer graphene. Assuming that the insulating phase is an ... More
FeTe$_{0.55}$Se$_{0.45}$: a multiband superconductor in the clean and dirty limitFeb 26 2015Apr 09 2015The detailed optical properties of the multiband iron-chalcogenide superconductor FeTe$_{0.55}$Se$_{0.45}$ have been reexamined for a large number of temperatures above and below the critical temperature $T_c=14$ K for light polarized in the a-b planes. ... More
Generalized isobaric multiplet mass equation and its application to the Nolen-Schiffer anomalyDec 25 2017Feb 02 2018The Wigner Isobaric Multiplet Mass Equation (IMME) is the most fundamental prediction in nuclear physics with the concept of isospin. However, it was deduced based on the Wigner-Eckart theorem with the assumption that all charge-violating interactions ... More
Overarching framework between Gaussian quantum discord and Gaussian quantum illuminationNov 30 2016Feb 28 2017We cast the problem of illuminating an object in a noisy environment into a communication protocol. A probe is sent into the environment, and the presence or absence of the object constitutes a signal encoded on the probe. The probe is then measured to ... More
Intra-day variability of three Seyfert Galaxies measured with XMM-NewtonMar 12 2019We present and analyze the variability of three Seyfert galaxies on intra-day timescales. We have analyzed in a uniform manner the 38 longest ( $>30$ ks) observations made for NGC 4051, MCG$-06-30-15$ and NGC 4151 by XMM-Newton between 2000 and 2015. ... More
Tuning the Resonance Properties of 2D Carbon Nanotube Networks towards Mechanical ResonatorJun 24 2015The capabilities of the mechanical resonator-based nanosensors in detecting ultra-small mass or force shifts have driven a continuing exploration of the palette of nanomaterials for such application purpose. Based on large-scale molecular dynamics simulations, ... More
Interplay between magnetism and superconductivity in iron-chalcogenide superconductors: crystal growth and characterizationsApr 04 2011Jul 09 2011In this review, we present a summary of the results on single crystal growth of two types of iron-chalcogenide superconductors, Fe(1+y)Te(1-x)Se(x) (11), and A(x)Fe(2-y)Se(2) (A= K, Rb, Cs, Tl, Tl/K, Tl/Rb), using Bridgman, zone-melting, vapor self-transport, ... More
Lattice dynamics of the high temperature shape memory alloy Nb-RuMar 01 2006Nb-Ru is a high temperature shape memory alloy that undergoes a Martensitic transformation from a parent cubic b-phase into a tetragonal b' phase at TM 900 C. Measurements of the phonon dispersion curves show that the [110]-TA2 phonon branch, corresponding ... More
On the interplay of paramagnetism and topology in the Fe-based High Tc SuperconductorsMar 25 2019The high Tc superconductor FeTe0.55Se0.45 has recently been shown to support a surface state with topological character. Here we use low-energy laser-based ARPES with variable light polarization, including both linear and circular polarization, to re-examine ... More
Reconstruction-Stabilized Epitaxy of LaCoO3/SrTiO3(111) Heterostructures by Pulsed Laser DepositionJan 04 2018Unlike widely explored complex oxide heterostructures grown along [001], the study of [111]-oriented heterointerfaces are very limited thus far. One of the main challenges is to overcome the polar discontinuity that hinders the epitaxy of atomically sharp ... More
Enhanced charge stripe order of superconducting La(2-x)Ba(x)CuO(4) in a magnetic fieldDec 14 2012The effect of a magnetic field on the charge stripe order in La(2-x)Ba(x)CuO(4) has been studied by means of high energy (100 keV) x-ray diffraction for charge carrier concentrations ranging from strongly underdoped to optimally doped. We find that charge ... More
Kepler-411: a four-planet system with an active host starFeb 26 2019We present a detailed characterization of the Kepler-411 system (KOI 1781). This system was previously known to host two transiting planets: one with a period of 3 days ($R=2.4R_\oplus$; Kepler-411b) and one with a period of 7.8 days ($R=4.4R_\oplus$; ... More
Experimental investigation of linear-optics-based quantum target detectionApr 12 2019The development of new techniques to improve measurements is crucial for all sciences. By employing quantum systems as sensors to probe some physical property of interest allows the application of quantum resources, such as coherent superpositions and ... More
Strong pinning in the hole-doped pnictide superconductor La$_{0.34}$Na$_{0.66}$Fe$_2$As$_2$Mar 10 2019We present magnetization studies as a function of time, temperature and magnetic field for $H$ $\parallel$ c-axis, in a hole-doped pnictide superconductor, La$_{0.34}$Na$_{0.66}$Fe$_2$As$_2$, with, $T_c$ $\approx$ 27 K. The obtained vortex phase-diagram ... More
Quantitative Raman measurements of the evolution of the Cooper-pairs density with doping in Bi2Sr2CaCu2O8+d superconductorsJan 17 2009Sep 21 2009We report Raman measurements on Bi2Sr2CaCu2O8+d single crystals which allow us to quantitavely evaluate the doping dependence of the density of Cooper pairs in the superconducting state. We show that the drastic loss of Cooper pairs in the antinodal region ... More
High Resolution Chandra Spectroscopy of Gamma Cassiopeia (B0.5IVe)Sep 10 2003Oct 13 2003gamma Cas has long been famous for its unique hard X-ray characteristics. We report herein on a 53 ks Chandra HETGS observation of this target. An inspection of our spectrum shows that it is quite atypical for a massive star, with abnormally weak Fe XXV, ... More
Determination of the optical properties of La{2-x}Ba{x}CuO{4} for several dopings, including the anomalous x=1/8 phaseOct 10 2011Apr 11 2012The optical properties the high-temperature superconductor La{2-x}Ba{x}CuO{4} have been measured over a wide frequency and temperature range for light polarized in the a-b planes and along the c axis. Three different Ba concentrations have been examined, ... More
Large Bi-2212 single crystal growth by the floating-zone techniqueMay 29 2008Effects of the growth velocity on the crystal growth behavior of Bi_2Sr_2Ca_1Cu_2O_x (Bi-2212) have been studied by floating zone technique. The results show that a necessary condition for obtaining large single crystals along the c-axis is that the solid-liquid ... More
Weightless: Lossy Weight Encoding For Deep Neural Network CompressionNov 13 2017The large memory requirements of deep neural networks limit their deployment and adoption on many devices. Model compression methods effectively reduce the memory requirements of these models, usually through applying transformations such as weight pruning ... More
Remarkable Stability of Charge Density Wave Order in La$_{1.875}$Ba$_{0.125}$CuO$_4$Jun 13 2016Mar 04 2018The occurrence of charge-density-wave (CDW) order in underdoped cuprates is now well established, although the precise nature of the CDW and its relationship with superconductivity is not. Theoretical proposals include contrasting ideas such as that pairing ... More
Science with hot astrophysical plasmasJul 05 2017We present some recent highlights and prospects for the study of hot astrophysical plasmas. Hot plasmas can be studied primarily through their X-ray emission and absorption. Most astrophysical objects, from solar system objects to the largest scale structures ... More
Charge order and low frequency spin dynamics in lanthanum cuprates revealed by Nuclear Magnetic ResonanceJul 02 2010We report detailed 17O, 139La, and 63Cu Nuclear Magnetic Resonance (NMR) and Nuclear Quadrupole Resonance (NQR) measurements in a stripe ordered La1.875Ba0.125CuO4 single crystal and in oriented powder samples of La1.8-xEu0.2SrxCuO4. We observe a partial ... More
Crossing on hyperbolic latticesNov 23 2011Jun 05 2012We divide the circular boundary of a hyperbolic lattice into four equal intervals, and study the probability of a percolation crossing between an opposite pair, as a function of the bond occupation probability p. We consider the {7,3} (heptagonal), enhanced ... More
Large magnetoresistance in La2/3Ca1/3MnO3 thin films induced by metal masked ion damage techniqueMar 09 2006e have developed a simple process to obtain large magnetoresistance (MR) in perovskite manganite thin films by a combination of focused ion beam (FIB) milling and 120 keV H$_{2}^{+}$ ion implantation. Metal slits about 70 nm in width were printed by 30 ... More
Digital Fourier transform spectroscopy: a high-performance, scalable technology for on-chip spectrum analysisFeb 15 2018Mar 16 2018Optical spectrum analysis is the cornerstone of spectroscopic sensing, optical network performance monitoring, and hyperspectral imaging. While conventional high-performance spectrometers used to perform such analysis are often large benchtop instruments, ... More
From Brittle to Ductile: A Structure Dependent Ductility of Diamond NanothreadNov 05 2015May 29 2016As a potential building block for the next generation of devices or multifunctional materials that are spreading almost every technology sector, one-dimensional (1D) carbon nanomaterial has received intensive research interests. Recently, a new ultra-thin ... More
Stimulation-based control of dynamic brain networksJan 05 2016The ability to modulate brain states using targeted stimulation is increasingly being employed to treat neurological disorders and to enhance human performance. Despite the growing interest in brain stimulation as a form of neuromodulation, much remains ... More
Beam energy dependence of the viscous damping of anisotropic flowMay 15 2013Aug 18 2013The flow harmonics $v_{2,3}$ for charged hadrons, are studied for a broad range of centrality selections and beam collision energies in Au+Au ($\sqrt{s_{NN}}= 7.7 - 200$ GeV) and Pb+Pb ($\sqrt{s_{NN}}= 2.76$ TeV) collisions. They validate the characteristic ... More
Metal-insulator-metal transition in NdNiO3 films capped by CoFe2O4Feb 07 2017Metal-insulator transition features as a transformation, from a highly charge conductive state to another state where charge conductivity is greatly suppressed when decreasing the temperature. Here we demonstrate two consecutive transitions in NdNiO3 ... More
Local Structure of the Superconductor K0.8Fe1.6+xSe2: Evidence of Large Structural DisorderNov 04 2011The local structure of superconducting single crystals of K0.8Fe1.6+xSe2 with Tc = 32.6 K was studied by x-ray absorption spectroscopy. Near-edge spectra reveal that the average valence of Fe is 2+. The room temperature structure about the Fe, K and Se ... More
Observing the ambiguity of simplicity via quantum simulations of an Ising spin chainNov 10 2017The modelling of stochastic processes is ubiquitous throughout the natural and social sciences. An ideal model produces the correct statistical output without any unnecessary complexity. This minimal-complexity criterion is important conceptually, entailing ... More
Low energy magnetic excitations from the Fe$_{1+y-z}$(Ni/Cu)$_{z}$Te$_{1-x}$Se$_{x}$ systemApr 04 2014We report neutron scattering measurements on low energy ($\hbar\omega \sim 5$~meV) magnetic excitations from a series of Fe$_{1+y-z}$(Ni/Cu)$_{z}$Te$_{1-x}$Se$_{x}$ samples which belong to the "11" Fe-chalcogenide family. Our results suggest a strong ... More
Electronic Raman Scattering in copper oxide Superconductors: Understanding the Phase DiagramMar 29 2011Apr 30 2011Electronic Raman scattering measurements have been performed on hole doped copper oxide superconductors as a function of temperature and doping level. In the superconducting state coherent Bogoliubov quasiparticles develop preferentially over the nodal ... More
On exterior calculus and curvature in piecewise-flat manifoldsDec 05 2012Simplicial, piecewise-flat discretizations of manifolds provide a clear path towards curvature analysis on discrete geometries and for solutions of PDE's on manifolds of complex topologies. In this manuscript we review and expand on discrete exterior ... More
Beyond Wigner's isobaric multiplet mass equation: Effect of charge-symmetry-breaking interaction and Coulomb polarizationJan 20 2016Feb 27 2019The quadratic form of the isobaric multiplet mass equation (IMME), which was originally suggested by Wigner and has been generally regarded as valid, is seriously questioned by recent high-precision nuclear mass measurements. The usual resolution to this ... More
Is anisotropic flow really acoustic?Jan 02 2013Aug 18 2013The flow harmonics for charged hadrons ($v_{n}$) and their ratios $(v_n/v_2)_{n\geq 3}$, are studied for a broad range of transverse momenta ($p_T$) and centrality ($\text{cent}$) in Pb+Pb collisions at $\sqrt{s_{NN}}= 2.76$ TeV. They indicate characteristic ... More
Influences of Si sheet doping densities on the morphological, conductive and optical characteristics of InAs/GaAs quantum dotsJun 10 2011The influences of Si sheet doping levels on the properties of InAs/GaAs quantum dots (QDs) are investigated by atomic force microscopy (AFM) and photoluminescence (PL). AFM measurements reveal that Si sheet doping doesn't change the morphology of InAs ... More
HL Tau disk in HCO+ (3-2) and (1-0) with ALMA: gas density, temperature, gap, and one-arm spiralJun 13 2019We present our observational results of the 1.1 mm continuum and the HCO+ (3-2) line in HL Tau at angular resolutions of 0.1" obtained with ALMA and our data analysis of the 2.9 mm and 1.1 mm continuum and the HCO+ (3-2) and (1-0) lines of the HL Tau ... More
Nonconvex Sparse Logistic Regression with Weakly Convex RegularizationAug 07 2017In this work we propose to fit a sparse logistic regression model by a weakly convex regularized nonconvex optimization problem. The idea is based on the finding that a weakly convex function as an approximation of the $\ell_0$ pseudo norm is able to ... More
An improved boundary condition at a low grid resolution and Reynolds numberJun 10 2018Complex geometries can be easily treated using the well-known full-way and half-way bounce-back rules. However, the accuracy of the full-way bounce-back rule is one order lower than the half-way bounce-back rule. Moreover, when the walls are not aligned ... More
Cooper Pairing in A Doped 2D Antiferromagnet with Spin-Orbit CouplingDec 21 2017We study the two-dimensional Hubbard model with the Rashba type spin-orbit coupling within and beyond the mean-field theory. The antiferromagnetic ground state for the model at half-filling and the Cooper pairing induced by antiferromagnetic spin fluctuations ... More
Magnetism and Thermodynamics of Spin-1/2 Heisenberg Diamond Chains in a Magnetic FieldApr 02 2007The magnetic and thermodynamic properties of spin-1/2 Heisenberg diamond chains are investigated in three different cases: (a) J1, J2, J3>0 (frustrated); (b) J1, J3<0, J2>0 (frustrated); and (c) J1, J2>0, J3<0 (non-frustrated). The density matrix renormalization ... More
Spectrum-Revealing Cholesky Factorization for Kernel MethodsApr 14 2018Kernel methods represent some of the most popular machine learning tools for data analysis. Since exact kernel methods can be prohibitively expensive for large problems, reliable low-rank matrix approximations and high-performance implementations have ... More
Leptogenesis with testable Dirac neutrino mass generationJul 22 2019A TeV-scale Higgs doublet can acquire a tiny vacuum expectation value via its small mixing with the standard model Higgs doublet. Ones then can realize a testable Dirac neutrino mass generation through the sizable Yukawa couplings among this new Higgs ... More
Bounds on Traceability SchemesSep 27 2016The Stinson-Wei traceability scheme (known as traceability scheme) was proposed for broadcast encryption as a generalization of the Chor-Fiat-Naor traceability scheme (known as traceability code). Cover-free family was introduced by Kautz and Singleton ... More
Optimal smoothing in nonparametric mixed-effect modelsJul 21 2005Mixed-effect models are widely used for the analysis of correlated data such as longitudinal data and repeated measures. In this article, we study an approach to the nonparametric estimation of mixed-effect models. We consider models with parametric random ... More
Thermodynamic potentials and Thermodynamic Relations in Nonextensive ThermodynamicsApr 02 2010Apr 05 2010The generalized Gibbs free energy and enthalpy is derived in the framework of nonextensive thermodynamics by using the so-called physical temperature and the physical pressure. Some thermodynamical relations are studied by considering the difference between ... More
A Randomized Algorithm for Preconditioner SelectionAug 01 2019The task of choosing a preconditioner $\boldsymbol{M}$ to use when solving a linear system $\boldsymbol{Ax}=\boldsymbol{b}$ with iterative methods is difficult. For instance, even if one has access to a collection $\boldsymbol{M}_1,\boldsymbol{M}_2,\ldots,\boldsymbol{M}_n$ ... More
Hedge and Mutual Funds' Fees and the Separation of Private InvestmentsAug 23 2012Oct 25 2014A fund manager invests both the fund's assets and own private wealth in separate but potentially correlated risky assets, aiming to maximize expected utility from private wealth in the long run. If relative risk aversion and investment opportunities are ... More