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Evolution of Magnetic Helicity During Eruptive Flares and Coronal Mass EjectionsJul 13 2016During eruptive solar flares and coronal mass ejections, a non-pot{\-}ential magnetic arcade with much excess magnetic energy goes unstable and reconnects. It produces a twisted erupting flux rope and leaves behind a sheared arcade of hot coronal loops. ... More

Exploring the biases of a new method based on minimum variance for interplanetary magnetic cloudsSep 03 2018Magnetic clouds (MCs) are twisted magnetic structures ejected from the Sun and probed by in situ instruments. They are typically modeled as flux ropes (FRs). The determination of the FR global characteristics requires the estimation of the FR axis orientation. ... More

Are There Different Populations of Flux Ropes in the Solar Wind?Jan 27 2014Flux ropes are twisted magnetic structures, which can be detected by in situ measurements in the solar wind. However, different properties of detected flux ropes suggest different types of flux-rope population. As such, are there different populations ... More

Global axis shape of magnetic clouds deduced from the distribution of their local axis orientationMay 17 2013Coronal mass ejections (CMEs) are routinely tracked with imagers in the interplanetary space while magnetic clouds (MCs) properties are measured locally by spacecraft. However, both imager and insitu data do not provide direct estimation on the global ... More

From coronal observations to MHD simulations, the building blocks for 3D models of solar flaresMay 20 2015Solar flares are energetic events taking place in the Sun's atmosphere, and their effects can greatly impact the environment of the surrounding planets. In particular, eruptive flares, as opposed to confined flares, launch coronal mass ejections into ... More

Generic magnetic field intensity profiles of interplanetary coronal mass ejections at Mercury, Venus and Earth from superposed epoch analysesJan 28 2019We study interplanetary coronal mass ejections (ICMEs) measured by probes at different heliocentric distances (0.3-1AU) to investigate the propagation of ICMEs in the inner heliosphere and determine how the generic features of ICMEs change with heliospheric ... More

On the Young-Fibonacci insertion algorithmApr 16 2007This work is concerned with some properties of the Young-Fibonacci insertion algorithm and its relation with Fomin's growth diagrams. It also investigates a relation between the combinatorics of Young-Fibonacci tableaux and the study of Okada's algebra ... More

Apparent and Intrinsic Evolution of Active Region UpflowsFeb 20 2017We analyze the evolution of Fe XII coronal plasma upflows from the edges of ten active regions (ARs) as they cross the solar disk using the Hinode Extreme Ultraviolet Imaging Spectrometer (EIS). Confirming the results of Demoulin et al. (2013, Sol. Phys. ... More

The standard flare model in three dimensions III. Slip-running reconnection propertiesMay 17 2013A standard model for eruptive flares aims at describing observational 3D features of the reconnecting coronal magnetic field. Extensions to the 2D model require the physical understanding of 3D reconnection processes at the origin of the magnetic configuration ... More

Root systems and graph associahedraFeb 12 2016It is known that a connected simple graph $G$ associates a simple polytope $P_G$ called a graph associahedron in Euclidean space. In this paper we show that the set of facet vectors of $P_G$ forms a root system if and only if $G$ is a cycle graph and ... More

The Development of Gas/Star Offsets in Tidal TailsNov 06 2000We present models of interacting galaxies in order to study the development of spatial offsets between the gaseous and stellar components in tidal tails. Observationally, such offsets are observed to exist over large scales (e.g., NGC 3690; Hibbard et ... More

Gas/Star Offsets in Tidal TailsAug 09 2000We use numerical simulations to study the development of gas/star offsets in the tidal tails of merging galaxies. These offsets are shown to be a natural consequence of the radially extended HI spatial distribution in disk galaxies, coupled with internal ... More

Morphology of Galaxy Mergers at Intermediate RedshiftOct 14 1994Using a combination of numerical simulation and synthesized Hubble Space Telescope Wide Field Camera 2 (HST WFC2) images, we follow the detectability of morphological signatures of disk galaxy mergers at intermediate redshifts z=0.4 and z=1.0. Rapid evolution ... More

Do mergers make (normal) ellipticals?Sep 06 2000Under the merger hypothesis, elliptical galaxies are built through mergers of gas-rich spirals. However, the relative paucity of HI in most normal ellipticals demands significant processing of atomic gas into other forms if this process is to be viable. ... More

Interactions and Mergers of Cluster GalaxiesMay 27 2003Jun 18 2003The high-density environment of galaxy clusters is ripe for collisional encounters of galaxies. While the large velocity dispersion of clusters was originally thought to preclude slow encounters, the infall of smaller groups into the cluster environment ... More

Interactions and mergers at higher redshiftOct 12 2000In models of hierarchical structure formation, interactions and mergers at high redshift play a key role in the formation and evolution of galaxies. Numerical modeling and observations of nearby systems explore the detailed physics of galaxy interactions, ... More

Non-equilibrium Kinematics in Merging GalaxiesOct 11 1999Measurements of the kinematics of merging galaxies are often used to derive dynamical masses, study evolution onto the fundamental plane, or probe relaxation processes. These measurements are often compromised to some degree by strong non-equilibrium ... More

Dynamics of MergersMar 08 1999I review the dynamics of galaxy mergers, paying particular attention to the triggering of gaseous inflows and onset of ultraluminous activity in galaxies.

The Evolution of Tidal DebrisJan 26 2004Galaxy interactions expel a significant amount of stars and gas into the surrounding environment. I review the formation and evolution of the tidal debris spawned during these collisions, and describe how this evolution depends on the large scale environment ... More

Optimization of Lattice QCD codes for the AMD Opteron processorOct 05 2005We report our experience of the optimization of the lattice QCD codes for the new Opteron cluster at DESY Hamburg, including benchmarks. Details of the optimization using SSE/SSE2 instructions and the effective use of prefetch instructions are discussed. ... More

Electric current in flares ribbons: observations and 3D standard modelFeb 10 2014Apr 23 2014We present for the first time the evolution of the photospheric electric currents during an eruptive X-class flare, accurately predicted by the standard 3D flare model. We analyze this evolution for the February 15, 2011 flare using HMI/SDO magnetic observations ... More

Slipping magnetic reconnection during an X-class solar flare observed by SDO/AIAJan 29 2014We present SDO/AIA observations of an eruptive X-class flare of July 12, 2012, and compare its evolution with the predictions of a 3D numerical simulation. We focus on the dynamics of flare loops that are seen to undergo slipping reconnection during the ... More

Comparing generic models for interplanetary shocks and magnetic clouds axis configurations at 1 AUMar 20 2015Interplanetary Coronal Mass Ejections are the manifestation of solar transient eruptions, which can significantly modify the plasma and magnetic conditions in the heliosphere. They are often preceded by a shock, and a magnetic flux rope is detected in ... More

Gasdynamics and Starbursts in Interacting GalaxiesNov 10 1997The onset of gaseous inflows and central activity in interacting galaxies is driven largely by induced bars in the host galaxies. The stability of galaxies against growing bar modes is a direct function of their structural properties --- galaxies with ... More

Uniqueness of the direct decomposition of toric manifoldsApr 03 2013In this paper, we study the uniqueness of the direct decomposition of a toric manifold. We first observe that the direct decomposition of a toric manifold as \emph{algebraic varieties} is unique up to order of the factors. An algebraically indecomposable ... More

A Generic Data Acquisition Framework For High Performance 2D X-RAY DetectorsJun 23 2018This paper presents the design criteria and the current implementation of a generic and functionally rich data acquisition framework for high performance detectors called RASHPA. The framework is based on the use of RDMA mechanisms for optimized data ... More

Dynamical Modeling of NGC 7252 and the Return of Tidal MaterialMar 07 1995Motivated by recent neutral hydrogen observations with the VLA, we have undertaken an investigation into the interaction that produced the well known merger remnant NGC 7252. Through fully self-consistent N-body simulations, we are able to reproduce the ... More

Finite size mass shift formula for stable particles revisitedSep 01 2004Luescher's finite size mass shift formula in a periodic finite volume, involving forward scattering amplitudes in the infinite volume, is revisited for the two stable distinguishable particle system. The generalized mass shift formulae for the boson and ... More

Excitation of Activity in Galaxies by Minor MergersJan 24 1995Mergers between gas--rich disks and less--massive dwarf galaxies are studied using numerical simulation. As the orbit of a satellite decays through dynamical friction, the primary disk develops large-amplitude spirals in response to its tidal forcing. ... More

Star Forming Galaxy Models: Blending Star Formation into TREESPHJun 14 1994We have incorporated star formation algorithms into a hybrid N-body/smoothed particle hydrodynamics code (TREESPH) in order to describe the star forming properties of disk galaxies over timescales of a few billion years. The models employ a Schmidt law ... More

The global well-posedness for the compressible fluid model of Korteweg typeAug 20 2019In this paper, we consider the compressible fluid model of Korteweg type which can be used as a phase transition model. It is shown that the system admits a unique, global strong solution for small initial data in $\mathbb R^N$, $N \geq 3$. In this study, ... More

Evolution of the Magnetic Field Distribution of Active RegionsSep 13 2016Aims. Although the temporal evolution of active regions (ARs) is relatively well understood, the processes involved continue to be the subject of investigation. We study how the magnetic field of a series of ARs evolves with time to better characterise ... More

Generalisation of the Magnetic Field Configuration of typical and atypical Confined FlaresNov 03 2018Atypical flares cannot be naturally explained with standard models. To predict such flares, we need to define their physical characteristics, in particular, their magnetic environment, and identify pairs of reconnected loops. Here, we present in detail ... More

Systematics of flux tubes in the dual Ginzburg-Landau theory and Casimir scaling hypothesis: folklore and lattice factsSep 05 2001Sep 16 2002The ratios between string tensions $\sigma_D$ of color-electric flux tubes in higher and fundamental SU(3) representations, $d_{D} \equiv \sigma_{D}/\sigma_{\bf 3}$, are systematically studied in a Weyl symmetric formulation of the DGL theory. The ratio ... More

NGC 2442: Tidal Encounters and the Evolution of Spiral GalaxiesJan 06 1997Using imaging Fabry-Perot data, we study the star-forming properties and kinematics of the nearby barred spiral galaxy NGC 2442. The Halpha emission is very localized along the strong spiral arms of the galaxy, and shows a marked asymmetry between the ... More

Ultraluminous Starbursts in Major MergersMay 16 1994We use numerical simulation to investigate the triggering of starbursts in merging disk galaxies. The properties of the merger-driven starbursts are sensitive to the structure of the progenitor galaxies; specifically, to the amount of material in a dense ... More

Dense Stellar Cores in Merger RemnantsSep 29 1994We use numerical models which include star formation to analyze the mass profiles of remnants formed by mergers of disk galaxies. During a merger, dissipation in gas and ensuing star formation leave behind a dense stellar core in the remnant. Rather than ... More

Intragroup and Intracluster LightOct 07 2015The largest stellar halos in the universe are found in massive galaxy clusters, where interactions and mergers of galaxies, along with the cluster tidal field, all act to strip stars from their host galaxies and feed the diffuse intracluster light (ICL) ... More

Global strings in five-dimensional supergravityDec 19 2015We show the existence of solitonic solutions of five-dimensional supergravity, which can be interpreted as global cosmic strings in our universe. They possess the same mathematical structure as the stringy cosmic strings studied by Greene, Shapere, Vafa ... More

Spin-dependent potentials from lattice QCDSep 29 2006Jan 23 2007The spin-dependent corrections to the static inter-quark potential are phenomenologically relevant to describing the fine and hyperfine spin splitting of the heavy quarkonium spectra. We investigate these corrections, which are represented as the field ... More

Halpha Velocity Mapping of Ultraluminous Infrared GalaxiesDec 04 1997We use imaging Fabry-Perot observations to explore the dynamical conditions in four southern ultraluminous (L_IR > 10^12 L_sun) infrared galaxies. These galaxies all show morphological and kinematic features indicative of a major merger, but span a wide ... More

Gasdynamics and Starbursts in Major MergersDec 14 1995Using numerical simulation, we study the development of gaseous inflows and triggering of starburst activity in mergers of comparable-mass disk galaxies. In all encounters studied, the galaxies experience strong gaseous inflows and moderate to intense ... More

Chemical abundances of field halo stars -- Implications for the building blocks of the Milky WayAug 26 2019I would like to review recent efforts of detailed chemical abundance measurements for field Milky Way halo stars. Thanks to the advent of wide-field spectroscopic surveys up to a several kpc from the Sun, large samples of field halo stars with detailed ... More

Heavy quarkonium spectroscopy in pNRQCD with lattice QCD inputNov 29 2012Dec 07 2012The charmonium and bottomonium mass spectra are investigated in potential nonrelativistic QCD (pNRQCD) with the heavy quark potential computed by lattice QCD simulations. The potential consists of a static potential and relativistic corrections classified ... More

More on the finite size mass shift formula for stable particlesApr 13 2005The next to leading order (NLO) contribution of the generalized finite size mass shift formula for an interacting two stable particle system in a periodic $L^{3}$ box is discriminated with maintaining its model independent structure and validity to all ... More

On the finite size mass shift formula for stable particlesJun 21 2004Feb 22 2005Luescher's finite size mass shift formula in a periodic finite volume, involving forward scattering amplitudes in the infinite volume, is revisited for the two stable distinguishable particle system. The generalized mass shift formulae for the boson and ... More

Scaling study of the relativistic corrections to the static potentialNov 17 2009The relativistic corrections to the static potential, i.e. the O(1/m) correction, the O(1/m^2) spin-dependent and momentum-dependent corrections are investigated in SU(3) lattice gauge theory. These corrections are relevant ingredients of an effective ... More

Remarks on hypergeometric Cauchy numbersFeb 15 2018Hypergeometric numbers can be recognized as one of the most natural extensions of the classical Cauchy numbers in terms of determinants, though many kinds of generalizations of the Cauchy numbers have been considered by many authors. In addition, there ... More

Brudno's theorem for Z^d (or Z^d_+) subshiftsAug 22 2015We generalize Brudno's theorem of $1$-dimensional shift dynamical system to $\mathbb{Z}^d$ (or $\mathbb{Z}_+^d$) subshifts. That is to say, in $\mathbb{Z}^d$ (or $\mathbb{Z}^d_+$) subshift, the Kolmogorov-Sinai entropy is equivalent to the Kolmogorov ... More

A family of pairs of imaginary cyclic fields of degree $(p-1)/2$ with both class numbers divisible by $p$Sep 21 2018We construct a new infinite family of pairs of imaginary cyclic fields of degree $(p-1)/2$ explicitly with both class numbers divisible by a given prime number $p$. For the proof, we use the fundamental unit of $\mathbb Q(\sqrt{p})$, certain units which ... More

On the Laxton GroupSep 21 2018Sep 26 2018We redefine a multiplicative group structure on the set of equivalence classes of rational sequences satisfying a fixed linear recurrence of degree two, which was defined by R. R. Laxton in his paper "On groups of linear recurrences I" published in Duke ... More

Slipping Magnetic Reconnection, Chromospheric Evaporation, Implosion, and Precursors in the 2014 September 10 X1.6-Class Solar FlareMar 19 2016We investigate the occurrence of slipping magnetic reconnection, chromospheric evaporation, and coronal loop dynamics in the 2014 September 10 X-class flare. The slipping reconnection is found to be present throughout the flare from its early phase. Flare ... More

Particle Acceleration In Plasmoid Ejections Derived From Radio Drifting Pulsating StructuresDec 26 2014We report observations of slowly drifting pulsating structures (DPS) in the 0.8-4.5 GHz frequency range of the RT4 and RT5 radio spectrographs at Ondrejov observatory, between 2002 and 2012. We found 106 events of drifting pulsating structures, which ... More

Sound Representation and Classification Benchmark for Domestic RobotsFeb 15 2014We address the problem of sound representation and classification and present results of a comparative study in the context of a domestic robotic scenario. A dataset of sounds was recorded in realistic conditions (background noise, presence of several ... More

Binary Search Tree insertion, the Hypoplactic insertion, and Dual Graded GraphsMay 18 2007Fomin (1994) introduced a notion of duality between two graded graphs on the same set of vertices. He also introduced a generalization to dual graded graphs of the classical Robinson-Schensted-Knuth algorithm. We show how Fomin's approach applies to the ... More

Relativistic corrections to the static potential at O(1/m) and O(1/m^2)Nov 15 2007We investigate the relativistic corrections to the static potential, i.e. the O(1/m) potential and the O(1/m^2) velocity-dependent potentials, in SU(3) lattice gauge theory. They are important ingredients of potential nonrelativistic QCD for heavy quarkonium. ... More

Capture and Annihilation of Dark Matter in Milky Way Globular ClustersFeb 10 2010Feb 12 2010Paper has been withdrawn due to a critical error in the numerical evaluation of the capture fraction.

Several properties of hypergeometric Bernoulli numbersMar 21 2018Sep 30 2018In this paper, we give the determinant expressions of the hypergeometric Bernoulli numbers, and some relations between the hypergeometric and the classical Bernoulli numbers which include Kummer's congruences. By applying Trudi's formula, we have some ... More

The Molecular ISM in Low Surface Brightness Disk GalaxiesNov 02 1998We present models for the interstellar medium in disk galaxies. In particular, we investigate whether the ISM in low surface brightness galaxies can support a significant fraction of molecular gas given their low metallicity and surface density. It is ... More

Glueball masses in 4d U(1) lattice gauge theory using the multi-level algorithmSep 01 2003Sep 04 2003We take a new look at plaquette-plaquette correlators in 4d compact U(1) lattice gauge theory which are separated in time, both in the confined and the deconfined phases. From the behaviour of these correlators we extract glueball masses in the scalar ... More

Casimir scaling hypothesis on the nonperturbative force in QCD vs. dual superconducting scenario of confinementDec 30 2002We discuss the Casimir scaling hypothesis on the nonperturbative force in terms of the dual superconducting picture of the QCD vacuum by calculating the string tensions of flux tubes associated with static charges in various SU(3) representations in the ... More

Chemical abundances of the Milky Way thick disk and stellar halo II.: sodium, iron-peak and neutron-capture elementsJun 05 2013We present chemical abundance analyses of sodium, iron-peak and neutron-capture elements for 97 kinematically selected thick disk, inner halo and outer halo stars with metallicities -3.3<[Fe/H]<-0.5. The main aim of this study is to examine chemical similarities ... More

Removing Internal Reflections from Deep Imaging DatasetsSep 17 2009We present a means of characterizing and removing internal reflections between the CCD and other optical surfaces in an astronomical camera. The stellar reflections appear as out-of-focus images and are not necessarily axisymmetric about the star. Using ... More

First-principles study of Exchange Interaction in Ising-type Multiferroic Ca$_3$CoMnO$_6$Apr 15 2014We perform first-principles calculations of multiferroic Ca$_3$CoMnO$_6$ and evaluate the exchange coupling constants using the Green's function method. We clarify the effect of intra-chain and inter-chain exchange interactions on magnetic stability. ... More

Dynamical Stability and Environmental Influences in Low Surface Brightness Disk GalaxiesDec 11 1996Using analytic stability criteria, we demonstrate that, due to their low surface mass density and large dark matter content, LSB disks are quite stable against the growth of global nonaxisymmetric modes such as bars. However, depending on their (poorly ... More

Dynamical Stability and Galaxy Evolution in LSB Disk GalaxiesNov 29 1996We demonstrate that, due to their low surface mass density and large dark matter content, LSB disks are quite stable against the growth of global bar modes. However, they may be only marginally stable against local disk instabilities. We simulate a collision ... More

Flavor independent systematics of excited baryons and intra-band transitionDec 30 2002Transitions among excited nucleons are studied within a non-relativistic quark model with a deformed harmonic oscillator potential. The transition amplitudes are factorized into the $l$-th moment and a geometrical factor. This fact leads to an analogous ... More

Nonperturbative determination of the QCD potential at O(1/m)Jul 07 2006Sep 23 2006The relativistic correction to the QCD static inter-quark potential at O(1/m) is investigated nonperturbatively for the first time by using lattice Monte Carlo QCD simulations. The correction is found to be comparable with the Coulombic term of the static ... More

Constraining Dark Halo Potentials with Tidal TailsFeb 16 1999We present an extensive parameter survey to study the influence of halo mass profiles on the development of tidal tails in interacting disk galaxies. We model the galaxies using a fixed exponential disk with a central bulge and vary the halo potential ... More

Electromagnetic transitions of excited baryons in a deformed oscillator quark modelOct 25 1999Sep 01 2000We study electromagnetic transitions of excited baryons in a deformed oscillator quark model, where baryon excited states are described as rotational bands of deformed intrinsic states. We describe all necessary tools to compute transition amplitudes ... More

Using Tidal Tails to Probe Dark Matter HalosSep 04 1995We use simulations of merging galaxies to explore the sensitivity of the morphology of tidal tails to variations of the halo mass distributions in the parent galaxies. Our goal is to constrain the mass of dark halos in well-known merging pairs. We concentrate ... More

Static potential, force, and flux-tube profile in 4D compact U(1) lattice gauge theory with the multi-level algorithmNov 11 2003Jun 03 2004The long range properties of four-dimensional compact U(1) lattice gauge theory with the Wilson action in the confinement phase is studied by using the multi-level algorithm. The static potential, force and flux-tube profile between two static charges ... More

Spatially Resolved Spectroscopy of Passive Spiral GalaxiesJan 07 2008Passive spiral galaxies, despite their spiral morphological appearance, do not have any emission lines indicative of ongoing star formation in their optical spectra. Previous studies have suggested that passive spiral galaxies preferentially exist in ... More

An LDPCC decoding algorithm based on Bowman-Levin approximation --Comparison with BP and CCCP--Oct 21 2004Jan 28 2005Belief propagation (BP) and the concave convex procedure (CCCP) are both methods that utilize the Bethe free energy as a cost function and solve information processing tasks. We have developed a new algorithm that also uses the Bethe free energy, but ... More

Determination of the spin-dependent potentials with the multi-level algorithmOct 10 2005The spin-dependent corrections to the static interquark potential are relevant to describing the fine and hyper-fine splittings of the heavy quarkonium spectra. We investigate these corrections in SU(3) lattice gauge theory with the Polyakov loop correlation ... More

Compensation of radiation damages for SOI pixel detector via tunnelingJul 10 2015Jul 14 2015We are developing monolithic pixel detectors based on SOI technology for high energy physics, X-ray applications and so on.To employ SOI pixel detector on such radiation environments, we have to solve effects of total ionizing dose (TID) for transistors ... More

Constraining dark halos with tidal tailsDec 08 1997Massive and extended dark halos can inhibit the formation of long tidal tails in galaxy collisions. We examine this effect using an extensive survey of simulations with different dark halo potentials to constrain halo properties of interacting galaxies. ... More

Tidal Tales Two: The Effect of Dark Matter Halos on Tidal Tail Morphology and KinematicsAug 01 1997We examine the effect of different dark matter halo potentials on the morphology and kinematics of tidals tails in a merger model of NGC 7252. We find that models of merging galaxies with low halo masses of Mh = 4-8 M{disk+bulge} (Mdb) can fit the observed ... More

Superconducting atomic contacts inductively coupled to a microwave resonatorSep 29 2014We describe and characterize a microwave setup to probe the Andreev levels of a superconducting atomic contact. The contact is part of a superconducting loop inductively coupled to a superconducting coplanar resonator. By monitoring the resonator reflection ... More

Superposed epoch study of ICME sub-structures near Earth and their effects on galactic cosmic raysMay 26 2016Jul 28 2016Interplanetary coronal mass ejections (ICMEs) are the interplanetary manifestations of solar eruptions. The overtaken solar wind forms a sheath of compressed plasma at the front of ICMEs. Magnetic clouds (MCs) are a subset of ICMEs with specific properties ... More

Chemical Feature of Eu abundance in the Draco dwarf spheroidal galaxyApr 13 2015Chemical abundance of r-process elements in nearby dwarf spheroidal (dSph) galaxies is a powerful tool to probe the site of r-process since their small-mass scale can sort out individual events producing r-process elements. A merger of binary neutron ... More

Chemical compositions of six metal-poor stars in the ultra-faint dwarf spheroidal galaxy Boötes IJan 07 2014Jan 08 2014Ultra-faint dwarf galaxies recently discovered around the Milky Way (MW) contain extremely metal-poor stars, and might represent the building blocks of low-metallicity components of the MW. Among them, the Bo\"otes I dwarf spheroidal galaxy is of particular ... More

Towards the String representation of the dual Abelian Higgs model beyond the London limitAug 20 2001Sep 16 2002We perform a path-integral analysis of the string representation of the dual Abelian Higgs (DAH) model beyond the London limit, where the string describing the vortex of a flux tube has a finite thickness. We show that besides an additional vortex core ... More

Chemical Compositions of Kinematically Selected Outer Halo StarsJul 01 2009Oct 09 2009Chemical abundances of 26 metal-poor dwarfs and giants are determined from high-resolution and high signal-to-noise ratio spectra obtained with Subaru/HDS. The sample is selected so that most of the objects have outer-halo kinematics. Self-consistent ... More

The Initial mass function of the first stars inferred from extremely metal-poor starsJan 23 2018Mar 07 2018We compare elemental abundance patterns of $\sim 200$ extremely metal-poor (EMP; [Fe/H]$<-3$) stars with supernova yields of metal-free stars in order to obtain insights into the characteristic masses of the first (Population III or Pop III) stars in ... More

Simulating Diffuse Light in Galaxy ClustersMar 08 2006Using N-body simulations, we have modeled the production and evolution of low surface brightness, diffuse intra-cluster light (ICL) in galaxy clusters. By creating simulated observations of the clusters we have measured the evolution of the ICL luminosity ... More

Quantifying the Fragility of Galactic Disks in Minor MergersOct 09 1995We perform fully self-consistent stellar dynamical simulations of the accretion of a companion ("satellite") galaxy by a large disk galaxy to investigate the interaction between the disk, halo, and satellite components of the system during a merger. Our ... More

Radial Gas Flows in Colliding Galaxies: Connecting Simulations and ObservationsJul 29 2004(abridged) We investigate the detailed response of gas to the formation of transient and long-lived dynamical structures induced in the early stages of a disk-disk collision, and identify observational signatures of radial gas inflow through a detailed ... More

Evolution of Flare Ribbons, Electric Currents and Quasi-separatrix Layers During an X-class FlareApr 25 2016The standard model for eruptive flares has in the past few years been extended to 3D. It predicts typical J-shaped photospheric footprints of the coronal current layer, forming at similar locations as the Quasi-Separatrix Layers (QSLs). Such a morphology ... More

Coupled MHD-Focused Transport Simulations for Modeling Solar Particle EventsMay 13 2019We describe the initial version of the Solar Particle Event (SPE) Threat Assessment Tool or STAT. STAT relies on elements of Corona-Heliosphere (CORHEL) and the Earth-Moon-Mars Radiation Environment Module (EMMREM), and allows users to investigate coronal ... More

CP-odd WWZ couplings induced by vector-like quarksFeb 26 1999Mar 13 1999A minimal extension of the standard model includes extra quarks with charges 2/3 and/or -1/3, whose left-handed and right-handed components are both SU(2) singlets. This model predicts new interactions of flavor-changing neutral current at the tree level, ... More

The origin of low [alpha/Fe] ratios in extremely metal-poor starsMar 07 2014We show that the low ratios of $\alpha$ elements (Mg, Si, and Ca) to Fe recently found for a small fraction of extremely metal-poor stars can be naturally explained with the nucleosynthesis yields of core-collapse supernovae, i.e., $13-25M_\odot$ supernovae, ... More

Diffuse Light in the Virgo ClusterAug 09 2005We present deep optical imaging of the inner 1.5 x 1.5 degrees of the Virgo cluster to search for diffuse intracluster light (ICL). Our image reaches a 1 sigma depth of mu_v=28.5 mag/arcsec^2 -- 1.5 mag/arcsec^2 deeper than previous surveys -- and reveals ... More

Discovery of a vast ionized gas cloud in the M51 systemApr 05 2018We present the discovery of a vast cloud of ionized gas 13$^{\prime}$ (32 kpc) north of the interacting system M51. We detected this cloud via deep narrow-band imaging with the Burrell Schmidt Telescope, where it appears as an extended, diffuse H$\alpha$-emitting ... More

Models of Cuspy Triaxial GalaxiesNov 28 2000We construct numerical models of mildly triaxial elliptical galaxies with central density cusps. Using a technique we call ``adiabatic squeezing'', we begin with a spherical gamma=1 Hernquist model and apply a drag to the velocities of the particles along ... More

The Quantity of Intracluster Light: Comparing Theoretical and Observational Measurement Techniques Using Simulated ClustersMar 07 2011Using a suite of N-body simulations of galaxy clusters specifically tailored to study the intracluster light (ICL) component, we measure the quantity of ICL using a number of different methods previously employed in the literature for both observational ... More

Strong coronal channelling and interplanetary evolution of a solar storm up to Earth and MarsJun 09 2015Jun 10 2015The severe geomagnetic effects of solar storms or coronal mass ejections (CMEs) are to a large degree determined by their propagation direction with respect to Earth. There is a lack of understanding of the processes that determine their non-radial propagation. ... More

CP-odd Anomalous W-boson Couplings from SupersymmetyOct 02 1997The supersymmetric standard model contains a new CP-violating phase in the mass matrices for charginos and neutralinos, which could induce CP-odd anomalous couplings for the WWZ and WW\gamma vertices at the one-loop level. We study these couplings, paying ... More

String representation of the dual Ginzburg-Landau theory beyond the London limitDec 30 2002The effective string action of the color-electric flux tube in the dual Ginzburg-Landau (DGL) theory is studied by performing a path-integral analysis by taking into account the finite thickness of the flux tube. A modified Yukawa interaction appears ... More

Optical high-resolution spectroscopy of 14 young $α$-rich starsApr 24 2018We report chemical abundances of 14 young $\alpha$-rich stars including neutron-capture elements based on high-quality optical spectra from HIRES/Keck I and differential line-by-line analysis. From the comparison of the abundance patterns of young $\alpha$-rich ... More