Results for "S. McKeown Walker"

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Band Structure and Spin-Orbital Texture of the (111)-KTaO3 Two-Dimensional Electron GasMar 14 2019Two-dimensional electron gases (2DEGs) in oxides show great potential for discovering new physical phenomena and at the same time hold promise for electronic applications. In this work we use angle resolved photoemission to determine the electronic structure ... More
In-situ strain-tuning of the metal-insulator-transition of Ca$_{2}$RuO$_{4}$ in angle-resolved photoemission experimentsMar 01 2018Oct 24 2018We report the evolution of the $k$-space electronic structure of lightly doped bulk Ca$_{2}$RuO$_{4}$ with uniaxial strain. Using ultrathin plate-like crystals, we achieve strain levels up to $-4.1\%$, sufficient to suppress the Mott phase and access ... More
Observation of out-of-plane spin texture in a SrTiO3 (111) two-dimensional electron gasJun 05 2018We explore the second order bilinear magnetoelectric resistance (BMER) effect in the d-electron-based two-dimensional electron gas (2DEG) at the SrTiO3 (111) surface. We find an evidence of a spin-split band structure with the archetypal spin-momentum ... More
Electronic structure of buried LaNiO3 layers in (111)-oriented LaNiO3/LaMnO3 superlattices probed by soft x-ray ARPESNov 25 2016Taking advantage of the large electron escape depth of soft x-ray angle resolved photoemission spectroscopy we report electronic structure measurements of (111)-oriented [LaNiO3/LaMnO3] superlattices and LaNiO3 epitaxial films. For thin films we observe ... More
High-resolution photoemission on Sr2RuO4 reveals correlation-enhanced effective spin-orbit coupling and dominantly local self-energiesDec 16 2018We explore the interplay of electron-electron correlations and spin-orbit coupling in the model Fermi liquid Sr2RuO4 using laser-based angle-resolved photoemission spectroscopy. Our precise measurement of the Fermi surface confirms the importance of spin-orbit ... More
Generating Bézout trees for Pythagorean pairsMar 13 2018Relatively prime pairs of integers can be represented as nodes in three way branching trees. We construct trees of B\'ezout coefficients which correspond to the relatively prime pairs in the aforementioned trees. As one application, we compare the B\'ezout ... More
ARPES Studies of Two-Dimensional Electron Gases at Transition Metal Oxide SurfacesDec 12 2016High mobility two-dimensional electron gases (2DEGs) underpin today's silicon based devices and are of fundamental importance for the emerging field of oxide electronics. Such 2DEGs are usually created by engineering band offsets and charge transfer at ... More
Exponential map and normal form for cornered asymptotically hyperbolic metricsSep 30 2016This paper considers asymptotically hyperbolic manifolds with a finite boundary intersecting the usual infinite boundary -- cornered asymptotically hyperbolic manifolds -- and proves a theorem of Cartan-Hadamard type near infinity for the normal exponential ... More
Jefferson Lab Science, Past and FutureDec 03 2014The Continuous Electron Beam Accelerator Facility (CEBAF) and associated experimental equipment at Jefferson Lab comprise a unique facility for experimental nuclear physics. This facility is presently being upgraded, which will enable a new experimental ... More
Formal theory of cornered asymptotically hyperbolic Einstein metricsAug 08 2017This paper makes a formal study of asymptotically hyperbolic Einstein metrics given, as conformal infinity, a conformal manifold with boundary. The space on which such an Einstein metric exists thus has a finite boundary in addition to the usual infinite ... More
DataJoint: A Simpler Relational Data ModelJul 29 2018The relational data model offers unrivaled rigor and precision in defining data structure and querying complex data. Yet the use of relational databases in scientific data pipelines is limited due to their perceived unwieldiness. We propose a simplified ... More
A new and efficient approach to time-dependent density-functional perturbation theory for optical spectroscopyAug 17 2005Using a super-operator formulation of linearized time-dependent density-functional theory, the dynamical polarizability of a system of interacting electrons is given a matrix continued-fraction representation whose coefficients can be obtained from the ... More
The quantum AdS_5 x S^5 superstring at finite couplingAug 22 2013The integrability of string theory in AdS_5 x S^5 and of the dilatation operator of N=4 super-Yang-Mills theory has been used to propose an exact solution to the spectral problem in these theories. Weak coupling perturbation theory both in gauge theory ... More
Real-Time Web Scale Event Summarization Using Sequential Decision MakingMay 12 2016We present a system based on sequential decision making for the online summarization of massive document streams, such as those found on the web. Given an event of interest (e.g. "Boston marathon bombing"), our system is able to filter the stream for ... More
A CO (J=3-2) Outflow Survey of the Elias 29 RegionFeb 28 2007We present a 5'x5' integrated intensity map of 12CO (J=3-2) emission from the rho-Ophiuchi cloud core that traces low-luminosity outflow emission from two protostars: Elias 29 and, most likely, LFAM 26. The morphology of the outflow from Elias 29 is bipolar ... More
The Cryogenic Target for the G$^0$ Experiment at Jefferson LabFeb 23 2005A cryogenic horizontal single loop target has been designed, built, tested and operated for the G$^0$ experiment in Hall C at Jefferson Lab. The target cell is 20 cm long, the loop volume is 6.5 l and the target operates with the cryogenic pump fully ... More
Stable commutator length in free products of cyclic groupsApr 23 2013We give an algorithm to compute stable commutator length in free products of cyclic groups which is polynomial time in the length of the input, the number of factors, and the orders of the finite factors. We also describe some experimental and theoretical ... More
Bifurcation of Positive Equilibria in Nonlinear Structured Population Models with Varying Mortality RatesFeb 09 2010A parameter-dependent model involving nonlinear diffusion for an age-structured population is studied. The parameter measures the intensity of the mortality. A bifurcation approach is used to establish existence of positive equilibrium solutions.
Global Bifurcation of Positive Equilibria in Nonlinear Population ModelsJul 07 2009Existence of nontrivial nonnegative equilibrium solutions for age structured population models with nonlinear diffusion is investigated. Introducing a parameter measuring the intensity of the fertility, global bifurcation is shown of a branch of positive ... More
An elementary view of familial pseudofunctorsDec 23 2018Mar 16 2019A classical result due to Diers shows that a presheaf $F\colon\mathcal{A}\to\mathbf{Set}$ on a category $\mathcal{A}$ is a coproduct of representables precisely when each connected component of $F$'s category of elements has an initial object. Most often, ... More
Yoneda structures and KZ doctrinesMar 25 2017Aug 09 2017In this paper we strengthen the relationship between Yoneda structures and KZ doctrines by showing that for any locally fully faithful KZ doctrine, with the notion of admissibility as defined by Bunge and Funk, all of the Yoneda structure axioms apart ... More
Positive Equilibrium Solutions for Age and Spatially Structured Population ModelsFeb 17 2009The existence of positive equilibrium solutions to age-dependent population equations with nonlinear diffusion is studied in an abstract setting. By introducing a bifurcation parameter measuring the intensity of the fertility it is shown that a branch ... More
Coexistence Steady States in a Predator-Prey ModelFeb 09 2010An age-structured predator-prey system with diffusion and Holling-Tanner-type nonlinearities is considered. Regarding the intensity of the fertility of the predator as bifurcation parameter, we prove that a branch of positive coexistence steady states ... More
Age-dependent equations with non-linear diffusionOct 30 2008We consider the well-posedness of models involving age structure and non-linear diffusion. Such problems arise in the study of population dynamics. It is shown how diffusion and age boundary conditions can be treated that depend non-linearly and possibly ... More
Automated Calibration System for a High-Precision Measurement of Neutrino Mixing Angle $θ_{13}$ with the Daya Bay Antineutrino DetectorsMay 10 2013We describe the automated calibration system for the antineutrino detectors in the Daya Bay Neutrino Experiment. This system consists of 24 identical units instrumented on 8 identical 20-ton liquid scintillator detectors. Each unit is a fully automated ... More
Spin-Orbit Torque and Nernst Effect in Bi-Sb/Co HeterostructuresOct 12 2018Harmonic measurements of the longitudinal and transverse voltages in Bi-Sb/Co bilayers are presented. A large second harmonic voltage signal due to the ordinary Nernst effect is observed. In experiments where a magnetic field is rotated in the film plane, ... More
R$^3$SGM: Real-time Raster-Respecting Semi-Global Matching for Power-Constrained SystemsOct 30 2018Stereo depth estimation is used for many computer vision applications. Though many popular methods strive solely for depth quality, for real-time mobile applications (e.g. prosthetic glasses or micro-UAVs), speed and power efficiency are equally, if not ... More
Star Formation in the Northern Cloud Complex of NGC 2264Mar 09 2006We have made continuum and spectral line observations of several outflow sources in the Mon OB1 dark cloud (NGC 2264) using the Heinrich Hertz Telescope (HHT) and ARO 12m millimeter-wave telescope. This study explores the kinematics and outflow energetics ... More
Synthesis of SnTe Nanoplates with {100} and {111} SurfacesJun 19 2014SnTe is a topological crystalline insulator that possesses spin-polarized, Dirac-dispersive surface states protected by crystal symmetry. Multiple surface states exist on the {100}, {110}, and {111} surfaces of SnTe, with the band structure of surface ... More
Quasiparticle dynamics and spin-orbital texture of the SrTiO3 two-dimensional electron gasMar 03 2014Sep 07 2014Two-dimensional electron gases (2DEGs) in SrTiO$_3$ have become model systems for engineering emergent behaviour in complex transition metal oxides. Understanding the collective interactions that enable this, however, has thus far proved elusive. Here ... More
Control of a two-dimensional electron gas on SrTiO3(111) by atomic oxygenMay 13 2014We report on the formation of a two-dimensional electron gas (2DEG) at the bare surface of (111) oriented SrTiO3. Angle resolved photoemission experiments reveal highly itinerant carriers with a 6-fold symmetric Fermi surface and strongly anisotropic ... More
Linear Structures in the Core of the Coma Cluster of GalaxiesSep 19 2013The hot X-ray emitting plasma in galaxy clusters is predicted to have turbulent motions which can contribute around ten percent of the cluster's central energy density. We report deep Chandra X-ray Observatory observations of the Coma cluster core, showing ... More
Generalized unitarity and the worldsheet S matrix in AdS_n x S^n x M^(10-2n)Apr 15 2013May 27 2014The integrability-based solution of string theories related to AdS(n)/CFT(n-1) dualities relies on the worldsheet S matrix. Using generalized unitarity we construct the terms with logarithmic dependence on external momenta at one- and two-loop order in ... More
Controlling bulk conductivity in topological insulators: Key role of anti-site defectsApr 18 2012The binary Bi-chalchogenides, Bi2Ch3, are widely regarded as model examples of a recently discovered new form of quantum matter, the three-dimensional topological insulator (TI) [1-4]. These compounds host a single spin-helical surface state which is ... More
On the magnetic structure of Sr3Ir2O7: an x-ray resonant scattering studyJul 01 2012This report presents azimuthal dependent and polarisation dependent x-ray resonant magnetic scattering at the Ir L3 edge for the bilayered iridate compound, Sr3Ir2O7. Two magnetic wave vectors, k1=(1/2,1/2,0) and k2=(1/2,-1/2,0), result in domains of ... More
LAAIR: A Layered Architecture for Autonomous Interactive RobotsNov 08 2018Nov 09 2018When developing general purpose robots, the overarching software architecture can greatly affect the ease of accomplishing various tasks. Initial efforts to create unified robot systems in the 1990s led to hybrid architectures, emphasizing a hierarchy ... More
The role of mutation rate variation and genetic diversity in the architecture of human diseaseAug 29 2013We have investigated the role that the mutation rate and the structure of genetic variation at a locus play in determining whether a gene is involved in disease. We predict that the mutation rate and its genetic diversity should be higher in genes associated ... More
The Effect of Resource Limits and Task Complexity on Collaborative Planning in DialogueNov 15 1995This paper shows how agents' choice in communicative action can be designed to mitigate the effect of their resource limits in the context of particular features of a collaborative planning task. I first motivate a number of hypotheses about effective ... More
Redundancy in Collaborative DialogueMar 16 1995In dialogues in which both agents are autonomous, each agent deliberates whether to accept or reject the contributions of the current speaker. A speaker cannot simply assume that a proposal or an assertion will be accepted. However, an examination of ... More
Experimentally Evaluating Communicative Strategies: The Effect of the TaskAug 24 1994Effective problem solving among multiple agents requires a better understanding of the role of communication in collaboration. In this paper we show that there are communicative strategies that greatly improve the performance of resource-bounded agents, ... More
Luminous "Dark" HalosAug 10 1999Aug 07 2000Several lines of evidence suggest that cold, dense gas clouds make a substantial contribution to the total mass of dark halos. If so then physical collisions between clouds must occur; these cause strong, radiative shocks to propagate through the cold ... More
Dark Matter in the Milky Way's Dwarf Spheroidal SatellitesMay 02 2012The Milky Way's dwarf spheroidal satellites include the nearest, smallest and least luminous galaxies known. They also exhibit the largest discrepancies between dynamical and luminous masses. This article reviews the development of empirical constraints ... More
Theory of Tunneling for Rough JunctionsMar 01 1999A formally exact expression for the tunneling current, for its separation into specular and diffuse components, and for its directionality, is given for a thick tunnel junction with rough interfaces in terms of the properties of appropriately defined ... More
Orthorhombically Mixed s and d$_{x^2-y^2}$ Wave Superconductivity and Josephson TunnelingOct 03 1995The effect of orthorhombicity on Josephson tunneling in high T$_c$ superconductors such as YBCO is studied for both single crystals and highly twinned crystals. It is shown that experiments on highly twinned crystals experimentally determine the symmetry ... More
Geodesic Rosen continued fractionsOct 06 2013Apr 21 2015We describe how to represent Rosen continued fractions by paths in a class of graphs that arise naturally in hyperbolic geometry. This representation gives insight into Rosen's original work about words in Hecke groups, and it also helps us to identify ... More
Determination of the Antiferroquadrupolar Order Parameters in UPd3Oct 26 2006By combining accurate heat capacity and X-ray resonant scattering results we have resolved the long standing question regarding the nature of the quadrupolar ordered phases in UPd_3. The order parameter of the highest temperature quadrupolar phase has ... More
Measurement of the Proton's Neutral Weak Magnetic Form FactorFeb 26 1997We report the first measurement of the parity-violating asymmetry in elastic electron scattering from the proton. The asymmetry depends on the neutral weak magnetic form factor of the proton which contains new information on the contribution of strange ... More
Phase-Sensitive Tetracrystal Pairing-Symmetry Measurements and Broken Time-Reversal Symmetry States of High Tc SuperconductorsApr 24 2000A detailed analysis of the symmetric tetracrystal geometry used in phase-sensitive pairing symmetry experiments on high Tc superconductors is carried out for both bulk and surface time-reversal symmetry-breaking states, such as the d+id' and d+is states. ... More
Centering, Anaphora Resolution, and Discourse StructureAug 11 1997Centering was formulated as a model of the relationship between attentional state, the form of referring expressions, and the coherence of an utterance within a discourse segment (Grosz, Joshi and Weinstein, 1986; Grosz, Joshi and Weinstein, 1995). In ... More
Limited Attention and Discourse StructureDec 18 1995Aug 14 1996This squib examines the role of limited attention in a theory of discourse structure and proposes a model of attentional state that relates current hierarchical theories of discourse structure to empirical evidence about human discourse processing capabilities. ... More
The Role of Cognitive Modeling in Achieving Communicative IntentionsJul 19 1994Jul 20 1994A discourse planner for (task-oriented) dialogue must be able to make choices about whether relevant, but optional information (for example, the "satellites" in an RST-based planner) should be communicated. We claim that effective text planners must explicitly ... More
Ancilla-Based Fortification of Phase Super-Sensitivity in Two-Photon InterferometeryNov 04 2016We show that the careful tailoring of an ancillary degree of freedom can increase the sensitivity of a quantum sensor. Specifically, through calculation of the Fisher information, we show that transformation and measurement of polarization correlations ... More
Orientations and p-Adic AnalysisApr 30 2009May 04 2009Matthew Ando produced power operations in the Lubin-Tate cohomology theories and was able to classify which complex orientations were compatible with these operations. The methods used by Ando, Hopkins and Rezk to classify orientations of topological ... More
Inferring Information Flow in Spike-train Data Sets using a Trial-Shuffle MethodFeb 17 2018Oct 25 2018Understanding information processing in the brain requires the ability to determine the functional connectivity between the different regions of the brain. We present a method using transfer entropy to extract this flow of information between brain regions ... More
Integer hulls of linear polyhedra and scl in familiesNov 05 2010Dec 10 2011The integer hull of a polyhedron is the convex hull of the integer points contained in it. We show that the vertices of the integer hulls of a rational family of polyhedra of size O(n) have quasipolynomial coordinates. As a corollary, we show that the ... More
On an age and spatially structured population model for Proteus Mirabilis swarm-colony developmentDec 20 2007Proteus mirabilis are bacteria that make strikingly regular spatial-temporal patterns on agar surfaces. In this paper we investigate a mathematical model that has been shown to display these structures when solved numerically. The model consists of an ... More
Causal Inference in Travel Demand Modeling (and the lack thereof)Jun 22 2017Dec 07 2017This paper is about the general disconnect that we see, both in practice and in literature, between the disciplines of travel demand modeling and causal inference. In this paper, we assert that travel demand modeling should be one of the many fields that ... More
Shellability and Regularity of Chain Complexes over a Principal RingDec 20 2011Oct 17 2012The goal of this paper is to generalize some of the existing toolkit of combinatorial algebraic topology in order to study the homology of abstract chain complexes. We define shellability of chain complexes in a similar way as for cell complexes and introduce ... More
On Multivariate Optimal TransportationJan 10 2018Sep 20 2018Optimal transports between multivariate distributions are difficult to find. Explicit results exist for multivariate Gaussian and special cases of elliptical distributions. Using results on the optimality of radial transformations and positive semidefinite ... More
On a model for a sliding droplet:Well-posedness and stability of translating circular solutionsMay 16 2017In this paper the model for a highly viscous droplet sliding down an inclined plane is analyzed. It is shown that, provided the slope is not too steep, the corresponding moving boundary problem possesses classical solutions. Well-posedness is lost when ... More
Parity-Violating Electron Scattering and the Electric and Magnetic Strange Form Factors of the NucleonJul 22 2012Measurement of the neutral weak vector form factors of the nucleon provides unique access to the strange quark content of the nucleon. These form factors can be studied using parity-violating electron scattering. A comprehensive program of experiments ... More
Extreme Scattering Events: insights into the interstellar medium on AU-scalesOct 25 2006Several radio-wave scintillation phenomena exhibit properties which are difficult to accommodate within the standard propagation model based on distributed Kolmogorov turbulence in the ionised ISM; here we discuss one such phenomenon, namely Extreme Scattering ... More
Supersymmetry and Chiral SymmetryDec 14 1999We dispute a recent claim for a nonperturbative nonrenormalisation theorem stating that mass cannot be spontaneously generated in supersymmetric QED. We also extend a long-standing perturbative result, namely that the effective potential is zero to all ... More
Extreme scattering of pulsarsNov 07 1999Extreme Scattering Events are radio-wave lensing events caused by AU-sized concentrations of ionised gas. Although they were discovered more than a decade ago we still have no clear picture of the physical nature of the lenses. To discriminate between ... More
A topos view of the type-2 fuzzy truth value algebraOct 17 2018It is known that fuzzy set theory can be viewed as taking place within a topos. There are several equivalent ways to construct this topos, one is as the topos of \'{e}tal\'{e} spaces over the topological space $Y=[0,1)$ with lower topology. In this topos, ... More
Uniqueness of Weak Solutions to a Prion Equation with Polymer JoiningMar 24 2017We consider a model for prion proliferation that includes prion polymerization, polymer splitting, and polymer joining. The model consists of an ordinary differential equation for the prion monomers and a hyperbolic nonlinear differential equation with ... More
Rational Singularities and Uniform Symbolic TopologiesOct 10 2015Oct 03 2017Take $(R, \mathfrak{m})$ any normal Noetherian domain, either local or $\mathbb{N}$-graded over a field. We study the question of when $R$ satisfies the uniform symbolic topology property (USTP) of Huneke, Katz, and Validashti: namely, that there exists ... More
Uniform Symbolic Topologies in Normal Toric RingsJun 20 2017Oct 03 2017Given a normal toric algebra $R$, we compute a uniform integer $D = D(R) > 0$ such that the symbolic power $P^{(D N)} \subseteq P^N$ for all $N >0$ and all monomial primes $P$. We compute the multiplier $D$ explicitly in terms of the polyhedral cone data ... More
A note on Non-Noetherian Cohen-Macaulay ringsDec 12 2018Jan 10 2019In this note, we study the Cohen-Macaulayness of non-Noetherian rings. We show that Hochster's celebrated theorem that a finitely generated normal semigroup ring is Cohen-Macaulay does not extend to non-Noetherian rings. We also show that for any valuation ... More
The Gromov boundary of the ray graphAug 16 2016The ray graph is a Gromov hyperbolic graph on which the mapping class group of the plane minus a Cantor set acts by isometries. We give a description of the Gromov boundary of the ray graph in terms of cliques of long rays on the plane minus a Cantor ... More
Surface subgroups from linear programmingDec 11 2012Jul 11 2014We show that certain classes of graphs of free groups contain surface subgroups, including groups with positive $b_2$ obtained by doubling free groups along collections of subgroups, and groups obtained by "random" ascending HNN extensions of free groups. ... More
The Large Magellanic Cloud and the Distance ScaleDec 14 2011The Magellanic Clouds, especially the Large Magellanic Cloud, are places where multiple distance indicators can be compared with each other in a straight-forward manner at considerable precision. We here review the distances derived from Cepheids, Red ... More
Ziggurats and rotation numbersOct 01 2011Dec 03 2011We establish the existence of new rigidity and rationality phenomena in the theory of nonabelian group actions on the circle, and introduce tools to translate questions about the existence of actions with prescribed dynamics into finite combinatorics. ... More
Uniform Symbolic Topologies via Multinomial ExpansionsMar 13 2017Dec 15 2017When does a Noetherian commutative ring $R$ have uniform symbolic topologies on primes--read, when does there exist an integer $D>0$ such that the symbolic power $P^{(Dr)} \subseteq P^r$ for all prime ideals $P \subseteq R$ and all $r >0$? Groundbreaking ... More
Absence of Giant Spin Splitting in the Two-Dimensional Electron Liquid at the Surface of SrTiO$_3$ (001)Mar 01 2016We reinvestigate the putative giant spin splitting at the surface of SrTiO$_3$ reported by Santander-Syro $et~al.$ [Nature Mat. 13, 1085 (2014)]. Our spin- and angle-resolved photoemission experiments on (001) oriented surfaces supporting a two-dimensional ... More
Observation of Large Topologically Trivial Fermi-Arcs in the Candidate Type-II Weyl Semimetal WTe2Apr 08 2016Sep 12 2016We report angle-resolved photoemission experiments resolving the distinct electronic structure of the inequivalent top and bottom (001) surfaces of WTe2. On both surfaces, we identify a surface state that forms a large Fermi-arc emerging out of the bulk ... More
Slaving of the magnetic moment canting to the correlated oxygen rotation in Sr2IrO4 revealed by X-ray resonant scatteringAug 29 2013Sep 27 2013Sr2IrO4 is a prototype of the class of Mott insulators in the strong spin-orbit interaction (SOI) limit described by a $J_{\mathrm{eff}}=1/2$ ground state. In Sr2IrO4, the strong SOI is predicted to manifest itself in the slaving of the canting of the ... More
Production of A=6,7 Nuclides in the Alpha + Alpha Reaction and Cosmic Ray NucleosynthesisApr 03 2001Cross sections for production of 6He, 6Li, 7Li, and 7Be in the alpha+alpha reaction were measured at bombarding energies of 159.3, 279.6, and 619.8 MeV, and are found to decrease rapidly with increasing energy. These cross sections are essential for the ... More
Collapse of the Mott gap and emergence of a nodal liquid in lightly doped Sr$_2$IrO$_4$Jun 01 2015Superconductivity in underdoped cuprates emerges from an unusual electronic state characterised by nodal quasiparticles and an antinodal pseudogap. The relation between this state and superconductivity is intensely studied but remains controversial. The ... More
Atomically precise lateral modulation of a two-dimensional electron liquid in anatase TiO2 thin filmsMar 01 2017Engineering the electronic band structure of two-dimensional electron liquids (2DELs) confined at the surface or interface of transition metal oxides is key to unlocking their full potential. Here we describe a new approach to tailoring the electronic ... More
Antiferromagnetic order and domains in Sr3Ir2O7 probed by x-ray resonant scatteringJan 06 2012This article reports a detailed x-ray resonant scattering study of the bilayer iridate compound, Sr3Ir2O7, at the Ir L2 and L3 edges. Resonant scattering at the Ir L3 edge has been used to determine that Sr3Ir2O7 is a long-range ordered antiferromagnet ... More
Dark matter profiles and annihilation in dwarf spheroidal galaxies: prospectives for present and future gamma-ray observatories - I. The classical dSphsApr 03 2011Jul 05 2011Due to their large dynamical mass-to-light ratios, dwarf spheroidal galaxies (dSphs) are promising targets for the indirect detection of dark matter (DM) in gamma-rays. We examine their detectability by present and future gamma-ray observatories. The ... More
Statistical Evaluation of Experimental Determinations of Neutrino Mass HierarchyOct 12 2012Dec 05 2012Statistical methods of presenting experimental results in constraining the neutrino mass hierarchy (MH) are discussed. Two problems are considered and are related to each other: how to report the findings for observed experimental data, and how to evaluate ... More
Spectroscopic evidence for polaronic behaviour of the strong spin-orbit insulator Sr$_3$Ir$_2$O$_7$Feb 02 2013We investigate the bilayer Ruddlesden-Popper iridate Sr$_3$Ir$_2$O$_7$ by temperature-dependent angle-resolved photoemission. We find a narrow-gap correlated insulator, with spectral features indicative of a polaronic ground state, strikingly similar ... More
Measurement of the vector analyzing power in elastic electron-proton scattering as a probe of double photon exchange amplitudesFeb 22 2000We report the first measurement of the vector analyzing power in inclusive transversely polarized elastic electron-proton scattering at Q^2 = 0.1 (GeV/c)^2 and large scattering angles. This quantity should vanish in the single virtual photon exchange, ... More
Neutrino mass hierarchy determination and other physics potential of medium-baseline reactor neutrino oscillation experimentsJul 28 2013Oct 01 2013Medium-baseline reactor neutrino oscillation experiments (MBRO) have been proposed to determine the neutrino mass hierarchy (MH) and to make precise measurements of the neutrino oscillation parameters. With sufficient statistics, better than ~3%/\sqrt{E} ... More
A Second Detector Focusing on the Second Oscillation Maximum at an Off-axis Location to Enhance the Mass Hierarchy Discovery Potential in LBNE10Jul 28 2013The Long Baseline Neutrino Oscillation Experiment (LBNE) is proposed to determine the neutrino mass hierarchy and measure the CP phase in the leptonic sector. The current design of LBNE Phase I consists of a 10 kt liquid argon time projection chamber ... More
Spin resonance in the superconducting state of Li$_{1-x}$Fe$_{x}$ODFe$_{1-y}$Se observed by neutron spectroscopyJul 19 2016We have performed inelastic neutron scattering measurements on a powder sample of the superconductor lithium iron selenide hydroxide Li$_{1-x}$Fe$_{x}$ODFe$_{1-y}$Se ($x \simeq 0.16, y \simeq 0.02$, $T_{\rm c} = 41$\,K). The spectrum shows an enhanced ... More
A Wind Tunnel in Your Classroom: The Design and Implementation of a Portable Wind Tunnel for Use in the Science ClassroomAug 09 2002This article describes a wind tunnel's ease of construction and its uses as a visualization tool that integrates concepts at the primary and secondary levels. An Appendix contains detailed building instructions. A web site (under construction) will provide ... More
Network architecture for a topological quantum computer in siliconJul 26 2018Nov 27 2018A design for a large-scale surface code quantum processor based on a node/network approach is introduced for semiconductor quantum dot spin qubits. The minimal node contains only 7 quantum dots, and nodes are separated on the micron scale, creating useful ... More
XMM-Newton observation of the ultraluminous quasar SDSS J010013.02+280225.8 at redshift 6.326May 18 2017A brief Chandra observation of the ultraluminous quasar, SDSS J010013.02+280225.8 at redshift 6.326, showed it to be a relatively bright, soft X-ray source with a count rate of about 1 ct/ks. In this paper we present results for the quasar from a 65ks ... More
Experimental Observation of Strong Coupling Between an Epsilon-Near-Zero Mode in a Deep Subwavelength Nanofilm and a Gap Plasmon ModeJan 09 2018Strong coupling is a phenomenon which occurs when the interaction between two resonance systems is so strong that the oscillatory energy exchange between them exceeds all dissipative loss channels. Each resonance can then no longer be described individually ... More
Exchange Interactions Mediated by Non-Magnetic Cations in Double PerovskitesFeb 25 2019Establishing the physical mechanism governing exchange interactions is fundamental for exploring exotic phases such as the quantum spin liquids (QSLs) in real materials. In this work, we address exchange interactions in Sr2CuTe$_{1-x}$W$_{x}$O, a series ... More
The ARIEL-CMU Systems for LoReHLT18Feb 24 2019This paper describes the ARIEL-CMU submissions to the Low Resource Human Language Technologies (LoReHLT) 2018 evaluations for the tasks Machine Translation (MT), Entity Discovery and Linking (EDL), and detection of Situation Frames in Text and Speech ... More
The POlarised GLEAM Survey (POGS) I: First Results from a Low-Frequency Radio Linear Polarisation Survey of the Southern SkySep 25 2018The low-frequency polarisation properties of radio sources are poorly studied, particularly in statistical samples. However, the new generation of low-frequency telescopes, such as the Murchison Widefield Array (MWA; the precursor for the low-frequency ... More
The Scalar Strange Content of the Nucleon from Lattice QCDJan 07 2013Jun 25 2013The scalar strange-quark matrix element of the nucleon is computed with lattice QCD. A mixed-action scheme is used with domain-wall valence fermions computed on the staggered MILC sea-quark configurations. The matrix element is determined by making use ... More
Feasibility Study of Social Media for Public Health Behaviour ChangesJan 13 2017Social networking sites such as Twitter and Facebook have been shown to function as effective social sensors that can "feel the pulse" of a community. The aim of the current study is to test the feasibility of designing, implementing and evaluating a ... More
Inferring Narrative Causality between Event Pairs in FilmsAug 30 2017To understand narrative, humans draw inferences about the underlying relations between narrative events. Cognitive theories of narrative understanding define these inferences as four different types of causality, that include pairs of events A, B where ... More
Realistic Surface Scattering and Surface Bound State Formation in the High T_c Superconductor YBa_2Cu_3O_{6+x}Sep 03 1998Surface Umklapp scattering of quasiparticles, and surface roughness are shown to play essential roles in the formation of the surface bound states in realistic models for YBa_2Cu_3O_{6+x}. The results account for the shape, the impurity dependence of ... More
Discrete-Lattice Model for Surface Bound States and Tunneling in d-Wave SuperconductorsMar 06 1998Surface bound states in a discrete-lattice model of a $d_{x^2 - y^2}$ cuprate superconductor are shown to be, in general, coherent superpositions of an incoming excitation and more than one outgoing excitation, and a simple graphical construction based ... More