Results for "Hidefumi Akiyama"

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Gorenstein cut polytopesFeb 12 2013Nov 01 2013An integral convex polytope ${\mathcal P}$ is said to be Gorenstein if its toric ring $K[{\mathcal P}]$ is normal and Gorenstein. In this paper, Gorenstein cut polytopes of graphs are characterized explicitly. First, we prove that Gorenstein cut polytopes ... More
Normality of cut polytopes of graphs is a minor closed propertyJun 29 2009Oct 04 2009Sturmfels-Sullivant conjectured that the cut polytope of a graph is normal if and only if the graph has no K_5 minor. In the present paper, it is proved that the normality of cut polytopes of graphs is a minor closed property. By using this result, we ... More
Intersubband absorption linewidth in GaAs quantum wells due to scattering by interface roughness, phonons, alloy disorder, and impuritiesAug 09 2002We calculate the intersubband absorption linewidth in quantum wells (QWs) due to scattering by interface roughness, LO phonons, LA phonons, alloy disorder, and ionized impurities, and compare it with the transport energy broadening that corresponds to ... More
Fourier imaging study of efficient near-field optical coupling in solid immersion fluorescence microscopyMay 02 2002We measured images and Fourier images of fluorescence for 0.11- and 0.22-$\mu$m-diameter dye-doped polystyrene micro-sphere beads on a solid immersion lens, and experimentally verified strongly-angle-dependent fluorescence intensities due to efficient ... More
Toric ideals and their circuitsOct 11 2012In this paper, we study toric ideals generated by circuits. For toric ideals which have squarefree quadratic initial ideals, a sufficient condition to be generated by circuits is given. In particular, squarefree Veronese subrings, the second Veronese ... More
A Gröbner basis characterization for chordal comparability graphsJan 31 2016Aug 04 2016In this paper, we study toric ideals associated with multichains of posets. It is shown that the comparability graph of a poset is chordal if and only if there exists a quadratic Gr\"obner basis of the toric ideal of the poset. Strong perfect elimination ... More
Reflexive polytopes arising from bipartite graphs with $γ$-positivity associated to interior polynomialsOct 29 2018Apr 27 2019In this paper, we introduce polytopes ${\mathcal B}_G$ arising from root systems $B_n$ and finite graphs $G$, and study their combinatorial and algebraic properties. In particular, it is shown that ${\mathcal B}_G$ is a reflexive polytope with a regular ... More
Reverse lexicographic squarefree initial ideals and Gorenstein Fano polytopesOct 17 2014Dec 30 2015Via the theory of reverse lexicographic squarefree initial ideals of toric ideals, we give a new class of Gorenstein Fano polytopes (reflexive polytopes) arising from a pair of stable set polytopes of perfect graphs.
Quantum wells with atomically smooth interfacesMay 09 2002By a cleaved-edge overgrowth method with molecular beam epitaxy and a (110) growth-interrupt-anneal, we have fabricated a GaAs quantum well exactly 30 monolayers thick bounded by atomically smooth AlGaAs hetero-interfaces without atomic roughness. Micro-photoluminescence ... More
Ambiguity of black hole entropy in loop quantum gravityAug 19 2005Nov 17 2005We reexmine some proposals of black hole entropy in loop quantum gravity (LQG) and consider a new possible choice of the Immirzi parameter which has not been pointed out so far. We also discuss that a new idea is inevitable if we regard the relation between ... More
Roots of the Ehrhart polynomial of hypersimplicesApr 29 2013Aug 14 2013The Ehrhart polynomial of the $d$-th hypersimplex $\Delta(d,n)$ of order $n$ is studied. By computational experiments and a known result for $d=2$, we conjecture that the real part of every roots of the Ehrhart polynomial of $\Delta(d,n)$ is negative ... More
Enriched order polytopes and Enriched Hibi ringsMar 03 2019Stanley introduced two classes of lattice polytopes associated to posets, which are called the order polytope ${\mathcal O}_P$ and the chain polytope ${\mathcal C}_P$ of a poset $P$. It is known that, given a poset $P$, the Ehrhart polynomials of ${\mathcal ... More
Toric ideals of finite graphs and adjacent 2-minorsAug 14 2011Oct 08 2012We study the problem when an ideal generated by adjacent 2-minors is the toric ideal of a finite graph.
Centrally symmetric configurations of integer matricesMay 22 2011The concept of centrally symmetric configurations of integer matrices is introduced. We study the problem when the toric ring of a centrally symmetric configuration is normal as well as is Gorenstein. In addition, Gr\"obner bases of toric ideals of centrally ... More
Reverse lexicographic Gröbner bases and strongly Koszul toric ringsFeb 14 2014Jun 05 2014Restuccia and Rinaldo proved that a standard graded $K$-algebra $K[x_1, ... x_n]/I$ is strongly Koszul if the reduced Gr\"obner basis of $I$ with respect to any reverse lexicographic order is quadratic. In this paper, we give a sufficient condition for ... More
Continuous area spectrum in regular black holeApr 07 2005May 23 2005We investigate highly damped quasinormal modes of regular black hole coupled to nonlinear electrodynamics. Using the WKB approximation combined with complex-integration technique, we show that the real part of the frequency disappears in the highly damped ... More
Non-very ample configurations arising from contingency tablesApr 23 2009Dec 08 2009In this paper, it is proved that, if a toric ideal possesses a fundamental binomial none of whose monomials is squarefree, then the corresponding semigroup ring is not very ample. Moreover, very ample semigroup rings of Lawrence type are discussed. As ... More
AGN Population at 10^-13 erg s-1 cm-2: Results from Optical Identification of ASCA SurveysJan 04 2001In this paper, results of optical identification of ASCA surveys are summarized. To understand luminous AGNs in the z<1 universe, the ASCA AGN sample is still better than samples of AGNs from deep Chandra or XMM-Newton surveys. Combining the identified ... More
The universal area spectrum in single-horizon black holesMay 22 2004Jun 16 2004We investigate highly damped quasinormal mode of single-horizon black holes motivated by its relation to the loop quantum gravity. Using the WKB approximation, we show that the real part of the frequency approaches the value $T_{\rm H}\ln 3$ for dilatonic ... More
Reflexive polytopes arising from bipartite graphs with $γ$-positivity associated to interior polynomialsOct 29 2018Nov 01 2018In this paper, we introduce polytopes ${\mathcal B}_G$ arising from root systems $B_n$ and finite graphs $G$, and study their combinatorial and algebraic properties. In particular, it is shown that ${\mathcal B}_G$ is a reflexive polytope with a regular ... More
Enriched chain polytopesDec 05 2018Stanley introduced a lattice polytope $\mathcal{C}_P$ arising from a finite poset $P$, which is called the chain polytope of $P$. The geometric structure of $\mathcal{C}_P$ has good relations with the combinatorial structure of $P$. In particular, the ... More
Toric rings and ideals of nested configurationsJul 19 2009Feb 07 2010The toric ring together with the toric ideal arising from a nested configuration is studied, with particular attention given to the algebraic study of normality of the toric ring as well as the Gr\"obner bases of the toric ideal. One of the combinatorial ... More
Two way subtable sum problems and quadratic Groebner basesNov 19 2007Jun 12 2008Hara, Takemura and Yoshida discuss toric ideals arising from two way subtable sum problems and shows that these toric ideals are generated by quadratic binomials if and only if the subtables are either diagonal or triangular. In the present paper, we ... More
The $h^*$-polynomials of locally anti-blocking lattice polytopes and their $γ$-positivityJun 11 2019A lattice polytope $\mathcal{P} \subset \mathbb{R}^d$ is called a locally anti-blocking polytope if for any closed orthant $\mathbb{R}^d_{\varepsilon}$ in $\mathbb{R}^d$, $\mathcal{P} \cap \mathbb{R}^d_{\varepsilon}$ is unimodularly equivalent to an anti-blocking ... More
Spiral Delone sets and three distance theoremApr 24 2019We show that a constant angle progression on the Fermat spiral forms a Delone set if and only if its angle is badly approximable.
Mean Divisibility of Multinomial coefficientsDec 16 2012Dec 06 2013Let m_1,...,m_s be positive integers. Consider the sequence defined by multinomial coefficients: a_n=\binom{(m_1+m_2+... +m_s)n}{m_1 n, m_2 n,..., m_s n}. Fix a positive integer k\ge 2. We show that there exists a positive integer C(k) such that \frac{\prod_{n=1}^t ... More
Spiral Delone sets and three distance theoremApr 24 2019Apr 30 2019We show that a constant angle progression on the Fermat spiral forms a Delone set if and only if its angle is badly approximable.
Strong coincidence and Overlap coincidenceSep 15 2015We show that strong coincidences of a certain many choices of control points are equivalent to overlap coincidence for the suspension tiling of Pisot substitution. The result is valid for degree $\ge 2$ as well, under certain topological conditions. This ... More
Host Galaxies of the High-redshift AGNs in the GOODS FieldsMay 16 2005The star-formation rates and the stellar masses of the host galaxies of AGNs at high-redshifts are keys to understanding the evolution of the relation between the mass of the spheroidal component of a galaxy and the mass of its central black hole. We ... More
Room-temperature excitonic absorption in quantum wiresMay 20 2005Jun 17 2005We measured absorption spectra of T-shaped quantum wires at room temperature using waveguide-transmission spectroscopy. Strong and narrow room-temperature one-dimensional-exciton absorption peak was observed, which shows peak modal absorption coefficient ... More
Evolution of excitons via biexcitons to an electron-hole plasma without level crossing between band edge and exciton in a quantum wireFeb 20 2004Mar 14 2005A recent single quantum wire is of sufficient quality to reveal new details of the photoluminescence (PL) evolution with increasing electron--hole (e--h) pair density. At a pair density of 3.6 $\times$ 10$^{3}$ cm$^{-1}$, the PL is characteristic of biexcitons ... More
Determination and Spectroscopy of Quantum Yields in Bio/Chemiluminescence via Novel Light-Collection-Efficiency Calibration: Reexamination of The Aqueous Luminol Chemiluminescence StandardOct 17 2006We have developed a luminescence-measurement system for liquid bio/chemiluminescence that can obtain quantitative luminescence spectra as the absolute total number of luminescence photons at each wavelength or photon energy and quantum yields. Calibration ... More
A family of non-sofic beta expansionsJan 24 2014Let \beta_n>1 be a root of x^n-x-1 for n=4,5,... We will prove that \beta_n is not a Parry number, i.e., the associated beta transformation does not correspond a sofic symbolic system. A generalization is shown in the last section.
Minimum polyhedron with $n$ verticesApr 11 2017Oct 15 2018We study a polyhedron with $n$ vertices of fixed volume having minimum surface area. Completing the proof of Toth, we show that all faces of a minimum polyhedron are triangles, and further prove that a minimum polyhedron does not allow deformation of ... More
Strong photo-absorption by a single quantum wire in waveguide-transmission spectroscopyFeb 15 2005We measured the absorption spectrum of a single T-shaped, 14x6 nm lateral-sized quantum wire embedded in an optical waveguide using waveguide-transmission spectroscopy at 5 K. In spite of its small volume, the one-dimensional-exciton ground state shows ... More
One-dimensional continuum and exciton states in quantum wiresSep 10 2002High-quality T-shaped quantum wires are fabricated by cleaved-edge overgrowth with the molecular beam epitaxy on the interface improved by a growth-interrupt high-temperature anneal. Characterization by micro-photoluminescence (PL) and PL excitation (PLE) ... More
Observation of large many-body Coulomb interaction effects in a doped quantum wireApr 14 2002We demonstrate strong one dimensional (1-D) many-body interaction effects in photoluminescence (PL) in a GaAs single quantum wire of unprecedented optical quality, where 1-D electron plasma densities are controlled via electrical gating. We observed PL ... More
Lasing from a single quantum wireSep 18 2002A laser with an active volume consisting of only a single quantum wire in the 1-dimensional (1-D) ground state is demonstrated. The single wire is formed quantum-mechanically at the T-intersection of a 14 nm Al_{0.07}Ga_{0.93}As quantum well and a 6 nm ... More
Ehrhart series of fractional stable set polytopes of finite graphsMar 31 2016Nov 29 2016The fractional stable set polytope ${\rm FRAC}(G)$ of a simple graph $G$ with $d$ vertices is a rational polytope that is the set of nonnegative vectors $(x_1,\ldots,x_d)$ satisfying $x_i+x_j\le 1$ for every edge $(i,j)$ of $G$. In this paper we show ... More
Strongly Koszul edge ringsOct 28 2013Jan 23 2014We classify the finite connected simple graphs whose edge rings are strongly Koszul. From the classification, it follows that if the edge ring is strongly Koszul, then its toric ideal possesses a quadratic Gr\"obner basis.
Toric rings and ideals of stable set polytopesMar 06 2016In this paper, we discuss the normality of the toric rings of stable set polytopes, and the set of generators and Gr\"obner bases of toric ideals of stable set polytopes by using the results on that of edge polytopes of finite nonsimple graphs. In particular, ... More
Polarization-dependent photoluminescence-excitation spectra of one-dimensional exciton and continuum states in T-shaped quantum wiresMar 17 2003Jul 09 2003We measured polarization-dependent photoluminescence-excitation spectra of highly uniform T-shaped quantum wires at 5 K. We attribute one peak to the 1D-exciton ground state and the continuous absorption band to 1D continuum states. These had similar ... More
Ehrhart series of fractional stable set polytopes of finite graphsMar 31 2016The fractional stable set polytope ${\rm FRAC}(G)$ of a simple graph $G$ with $d$ vertices is a rational polytope that is the set of nonnegative vectors $(x_1,\ldots,x_d)$ satisfying $x_i+x_j\le 1$ for every edge $(i,j)$ of $G$. In this paper we show ... More
Imaging of emission patterns in a T-shaped quantum wire laserMar 18 2003Spatially and spectrally resolved microscopic images of spontaneous and stimulated emissions are imaged at the mirror facets of a GaAs T-shaped quantum wire laser with high uniformity. Laser emission from the one-dimensional ground state reveals a circular ... More
Intersubband electronic Raman scattering in narrow GaAs single quantum wells dominated by single-particle excitationsJun 08 2004We measured resonant Raman scattering by intersubband electronic excitations in GaAs/AlAs single quantum wells (QWs) with well widths ranging from 8.5 to 18 nm. In narrow (less than 10 nm) QWs with sufficiently high electron concentrations, only single-particle ... More
Quantum-dot single-photon source on a CMOS silicon photonic chip integrated using transfer printingDec 31 2018Silicon photonics is a powerful platform for implementing large-scale photonic integrated circuits (PICs), because of its compatibility with mature complementary-metal-oxide-semiconductor (CMOS) technology. Exploiting silicon-based PICs for quantum photonic ... More
Heterogeneity of link weight and the evolution of cooperationJul 24 2015Oct 31 2015In this paper, we investigate the effect of "heterogeneity of link weight", heterogeneity of the frequency or amount of interactions among individuals, on the evolution of cooperation. Based on an analysis of the evolutionary prisoner's dilemma game on ... More
Quantum Phase Transition in Antiferromagnetic Heisenberg Chains Coupled to PhononsAug 30 2011We develop an analytical approach based on a unitary transformation to investigate S=1/2 antiferromagnetic Heisenberg chains coupled to phonons, and find a new quantum phase transition at zero temperature. Although the usual phase transition occurs depending ... More
Spatially resolved stellar mass buildup and quenching in massive disk galaxies over the last 10 Gyr revealed with spatially resolved SED fittingFeb 20 2019Despite decreasing cosmic star formation rate density over the last 10 Gyr, the stellar mass ($M_{*}$) buildups in galaxies were still progressing during this epoch. About 50\% of the current $M_{*}$ density in the universe was built over the last $\sim ... More
Comments on the height reducing propertyMay 06 2012Dec 20 2012A complex number alpha is said to satisfy the height reducing property if there is a finite subset F of the ring Z of the rational integers such that Z[alpha]=F[alpha]. This problem of finding F has been considered by several authors, especially in contexts ... More
Topology and Energetics of Metal-Encapsulating Si Fullerene-Like Cage ClustersJul 27 2001Aug 09 2001On the basis of a topological discussion as well as an {\it ab initio} calculation, we show that it is possible to construct a fullerene-like Si cage by doping of a transition metal atom. The cage is a simple 3-polytope which maximizes the number of its ... More
Roots of Ehrhart polynomials of Gorenstein Fano polytopesJan 23 2010Given arbitrary integers $k$ and $d$ with $0 \leq 2k \leq d$, we construct a Gorenstein Fano polytope $\Pc \subset \RR^d$ of dimension $d$ such that (i) its Ehrhart polynomial $i(\Pc, n)$ possesses $d$ distinct roots; (ii) $i(\Pc, n)$ possesses exactly ... More
Markov chain Monte Carlo methods for the Box-Behnken designs and centrally symmetric configurationsFeb 09 2015We consider Markov chain Monte Carlo methods for calculating conditional p values of statistical models for count data arising in Box-Behnken designs. The statistical model we consider is a discrete version of the first-order model in the response surface ... More
Unmixed bipartite graphs and sublattices of the Boolean latticesJun 06 2008The correspondence between unmixed bipartite graphs and sublattices of the oolean lattice is discussed. By using this correspondence, we show the existence of squarefree quadratic initial ideals of toric ideals arising from minimal vertex covers of unmixed ... More
Nonrigid chiral soliton for the octet and decuplet baryonsOct 01 2003Systematic treatment of the collective rotation of the nonrigid chiral soliton is developed in the SU(3) chiral quark soliton model and applied to the octet and decuplet baryons. The strangeness degrees of freedom are treated by a simplified bound-state ... More
Invariant measure of rotational beta expansion and a problem of TarskiSep 16 2015Nov 28 2016We study invariant measures of a piecewise expanding map in $\mathbb{R}^m$ defined by an expanding similitude modulo lattice. Using the result of Bang on a problem of Tarski, we show that when the similarity ratio is not less than $m+1$, it has an absolutely ... More
Stability of the rotating SU(3) SkyrmionSep 18 2007Nov 13 2007The profile functions of the SU(3) Skyrme soliton are investigated for the octet, decuplet, and antidecuplet baryons by the mean field approach. In this approach, the profile functions are affected by the spatial rotation, the flavor rotation, and the ... More
Quantum corrections to the masses of the octet and decuplet baryons in the SU(3) chiral quark soliton modelJul 29 2006Mesonic fluctuations around the chiral solitons are investigated in the SU(3) chiral quark soliton model. Since the soliton takes the non-hedgehog shape for the hyperons and the hedgehog one for the non-hedgehog baryons in our approach, the fluctuations ... More
An Extremely Red Nucleus in an Absorbed QSO at z=0.65Dec 27 2000The results of K-band-imaging observations of a candidate of an absorbed QSO at z=0.653, AX J131831+3341, are presented. The B-K color of the object is 4.85 mag, which is much redder than optically-selected QSOs. The K-band image shows nuclear and extended ... More
Rotational beta expansion: Ergodicity and SoficnessFeb 06 2015Sep 15 2015We study a family of piecewise expanding maps on the plane, generated by composition of a rotation and an expansive similitude of expansion constant $\beta$. We give two constants $B_1$ and $B_2$ depending only on the fundamental domain that if $\beta>B_1$ ... More
Evolution of spatially resolved star formation main sequence and surface density profiles in massive disc galaxies at $0\lesssim z \lesssim 1$: inside-out stellar mass buildup and quenchingFeb 11 2018Aug 20 2018We investigate a relation between surface densities of star formation rate (SFR) and stellar mass ($M_{*}$) at a $\sim 1$ kpc scale namely spatially resolved star formation main sequence (SFMS) in massive ($\log(M_{*}/M_{\odot})>10.5$) face-on disc galaxies ... More
Higher Order Oscillation and Uniform DistributionDec 26 2016It is known that the M\"obius function in number theory is higher order oscillating. In this paper we show that there is another kind of higher order oscillating sequences in the form $(e^{2\pi i \alpha \beta^{n}g(\beta)})_{n\in \N}$, for a non-decreasing ... More
Yet another characterization of the Pisot substitution conjectureOct 08 2018We give a sufficient geometric condition for a subshift to be measurably isomorphic to a domain exchange and to a translation on a torus. And for an irreducible unit Pisot substitution, we introduce a new topology on the discrete line and we give a simple ... More
Gain in a quantum wire laser of high uniformityJun 08 2002A multi-quantum wire laser operating in the 1-D ground state has been achieved in a very high uniformity structure that shows free exciton emission with unprecedented narrow width and low lasing threshold. Under optical pumping the spontaneous emission ... More
Instability of the hedgehog shape for the octet baryon in the chiral quark soliton modelMay 12 2003In this paper the stability of the hedgehog shape of the chiral soliton is studied for the octet baryon with the SU(3) chiral quark soliton model. The strangeness degrees of freedom are treated by a simplified bound-state approach, which omits the locality ... More
Invariant measure of rotational beta expansion and a problem of TarskiSep 16 2015We study invariant measures of a piecewise expanding map in $\mathbb{R}^m$ defined by an expanding similitude modulo lattice. Using the result of Bang on a problem of Tarski, we show that when the similarity ratio is not less than $m+1$, it has an absolutely ... More
Evolution of Cooperation, Differentiation, Complexity, and Diversity in an Iterated Three-person GameApr 10 1995A non-zero-sum 3-person coalition game is presented, to study the evolution of complexity and diversity in cooperation, where the population dynamics of players with strategies is given according to their scores in the iterated game and mutations. Two ... More
Understanding the Scatter in the Spatially-resolved Star Formation Main Sequence of Local Massive Spiral GalaxiesApr 15 2017We investigate the relation between star formation rate (SFR) and stellar mass ($M_*$) in sub-galactic ($\sim 1$kpc) scale of 93 local ($0.01<z<0.02$) massive ($M_*>10^{10.5}M_{\odot}$) spiral galaxies. To derive spatially-resolved SFR and stellar mass, ... More
Discretized rotation has infinitely many periodic orbitsJun 18 2012Dec 20 2012For a fixed k in (-2,2), the discretized rotation on Z^2 is defined by (x,y)->(y,-[x+ky]). We prove that this dynamics has infinitely many periodic orbits.
Discrete spectra and Pisot numbersMar 23 2011By the m-spectrum of a real number q>1 we mean the set Y^m(q) of values p(q) where p runs over the height m polynomials with integer coefficients. These sets have been extensively investigated during the last fifty years because of their intimate connections ... More
Markov chain Monte Carlo methods for the regular two-level fractional factorial designs and cut idealsFeb 12 2013It is known that a Markov basis of the binary graph model of a graph $G$ corresponds to a set of binomial generators of cut ideals $I_{\widehat{G}}$ of the suspension $\widehat{G}$ of $G$. In this paper, we give another application of cut ideals to statistics. ... More
Determination of the Number of Graphene Layers: Discrete Distribution of the Secondary Electron Intensity Derived from Individual Graphene LayersAug 12 2010Sep 28 2010Using a scanning electron microscope, we observed a reproducible, discrete distribution of secondary electron intensity stemming from an atomically thick graphene film on a thick insulating substrate. The discrete distribution made it possible to uniquely ... More
Integer decomposition property for Cayley sums of order and stable set polytopesJul 16 2018Lattice polytopes which possess the integer decomposition property (IDP for short) turn up in many fields of mathematics. It is known that if the Cayley sum of lattice polytopes possesses IDP, then so does their Minkowski sum. In this paper, the Cayley ... More
The number of $4$-cycles and the cyclomatic number of a finite simple graphJan 18 2018Let $G$ be a finite connected simple graph with $d$ vertices and $e$ edges. The cyclomatic number $e-d+1$ of $G$ is the dimension of the cycle space of $G$. Let $c_4(G)$ denote the number of $4$-cycles of $G$ and $k_4(G)$ that of $K_4$, the complete graph ... More
Powers of componentwise linear idealsApr 27 2009We give criteria for graded ideals to have the property that all their powers are componentwise linear. Typical examples to which our criteria can be applied include the vertex cover ideals of certain finite graphs.
The Fate of a Five-Dimensional Rotating Black Hole via Hawking RadiationFeb 21 2005Aug 23 2005We study the evolution of a five-dimensional rotating black hole emitting scalar field radiation via the Hawking process for arbitrary initial values of the two rotation parameters $a$ and $b$. It is found that any such black hole whose initial rotation ... More
Algorithm for determining pure pointedness of self-affine tilingsMar 15 2010Overlap coincidence in a self-affine tiling in $\R^d$ is equivalent to pure point dynamical spectrum of the tiling dynamical system. We interpret the overlap coincidence in the setting of substitution Delone set in $\R^d$ and find an efficient algorithm ... More
The computation of overlap coincidence in Taylor-Socolar substitution tilingDec 18 2012Recently Taylor and Socolar introduced an aperiodic mono-tile. The associated tiling can be viewed as a substitution tiling. We use the substitution rule for this tiling and apply the algorithm of \cite{AL} to check overlap coincidence. It turns out that ... More
"Visible" 5d orbital states in a pleochroic oxychlorideApr 12 2019Transition metal compounds sometimes exhibit beautiful colors. We report here on a new oxychloride Ca3ReO5Cl2 which shows unusually distinct pleochroism; that is, the material exhibits different colors depending on viewing directions. This ple-ochroism ... More
De-leptonization and Non-Axisymmetric Instabilities in Core Collapse SupernovaeSep 26 2006The timescale of de-leptonization by neutrino loss and associated contraction of a proto-neutron star is short compared to the time to progagate a shock through the helium core of a massive star, and so the de-leptonization phase does not occur in the ... More
Magnetic Fields in Core Collapse Supernovae: Possibilities and GapsDec 15 2004Spectropolarimetry of core collapse supernovae has shown that they are asymmetric and often, but not universally, bi-polar. The Type IIb SN1993J and similar events showed large scatter in the Stokes parameter plane. Observational programs clearly have ... More
MHD Simulations of Core Collapse Supernovae with Cosmos++Aug 08 2010We performed 2D, axisymmetric, MHD simulations with Cosmos++ in order to examine the growth of the magnetorotational instability (MRI) in core--collapse supernovae. We have initialized a non--rotating 15 solar mass progenitor, infused with differential ... More
The Non-Monotonic Dependence of Supernova and Remnant Formation on Progenitor RotationApr 26 2005May 02 2005Traditional models of core collapse suggest the issue of successful versus failed supernova explosions and neutron star versus black hole formation depends monotonically on the mass (and metallicity) of the progenitor star. Here we argue that the issue ... More
Magnetic Field in SupernovaeNov 20 2002A relatively modest value of the initial rotation of the iron core, a period of ~ 6-31 s, will give a very rapidly rotating protoneutron star and hence strong differential rotation with respect to the infalling matter. Under these conditions, a seed field ... More
Overlap coincidence to strong coincidence in substitution tiling dynamicsMar 03 2014Overlap coincidence is an equivalent criterion to pure discrete spectrum of the dynamics of self affine tilings. In the case of one dimension, strong coincidence on m letter irreducible substitution has been introduced in Dekking (1978) and Arnoux and ... More
Enhanced thermopower via spin-state modificationJul 02 2018We investigated the effect of pressure on the magnetic and thermoelectric properties of Sr$_{3.1}$Y$_{0.9}$Co$_{4}$O$_{10+\delta }$. The magnetization is reduced with the application of pressure, reflecting the spin-state modification of the Co$^{3+}$ ... More
Shear viscosity of classical fields in scalar theoryApr 04 2019We investigate the shear viscosity of classical scalar fields in the $\phi^4$ theory on a lattice by using the Green-Kubo formula. Equilibrium expectation value of the time correlation function of the energy-momentum tensor is evaluated as the ensemble ... More
Roots of Ehrhart polynomials arising from graphsMar 29 2010Dec 29 2010Several polytopes arise from finite graphs. For edge and symmetric edge polytopes, in particular, exhaustive computation of the Ehrhart polynomials not merely supports the conjecture of Beck {\it et al.}\ that all roots $\alpha$ of Ehrhart polynomials ... More
Interstellar Scintillation and the Radio Counterpart of the Fast Radio Burst FRB150418Mar 15 2016May 14 2016Keane et al. (2016) have recently reported the discovery of a new fast radio burst, FRB150418, with a promising radio counterpart at 5.5 and 7.5 GHz -- a rapidly decaying source, falling from 200-300 $\mu$Jy to 100 $\mu$Jy on timescales of $\sim$6 d. ... More
Centrally symmetric configurations of order polytopesSep 15 2014Apr 04 2015It is shown that the toric ideal of the centrally symmetric configuration of the order polytope of a finite partially ordered set possesses a squarefree quadratic initial ideal. It then follows that the convex polytope arising from the centrally symmetric ... More
Groebner bases of nested configurationsJan 07 2008In this paper we introduce a new and large family of configurations whose toric ideals possess quadratic Groebner bases. As an application, a generalization of algebras of Segre-Veronese type will be studied.
The number of edges of the edge polytope of a finite simple graphAug 16 2013Jan 07 2016Let $d \geq 3$ be an integer. It is known that the number of edges of the edge polytope of the complete graph with $d$ vertices is $d(d-1)(d-2)/2$. In this paper, we study the maximum possible number $\mu_d$ of edges of the edge polytope arising from ... More
Kinematic and Energetic Properties of the 2012 March 12 Polar Coronal Mass EjectionJul 15 2015We report on the energetics of the 2012 March 12 polar coronal mass ejection (CME) originating from a southern latitude of ~60o. The polar CME is similar to low-latitude CMEs in almost all respects: three-part morphology, post eruption arcade (PEA), CME ... More
The Effects of Accretion Flow Dynamics on the Black Hole Shadow of Sagittarius A$^{*}$Aug 10 2016A radiatively inefficient accretion flow (RIAF), which is commonly characterized by its sub-Keplerian nature, is a favored accretion model for the supermassive black hole at Galactic center, Sagittarius A$^{*}$. To investigate the observable features ... More
Topology of planar self-affine tiles with collinear digit setJan 09 2018We consider the self-affine tiles with collinear digit set defined as follows. Let $A,B\in\mathbb{Z}$ satisfy $|A|\leq B\geq 2$ and $M\in\mathbb{Z}^{2\times2}$ be an integral matrix with characteristic polynomial $x^2+Ax+B$. Moreover, let $\mathcal{D}=\{0,v,2v,\ldots,(B-1)v\}$ ... More
On B. Mossé's unilateral recognizability theoremDec 27 2017We complete statement and proof for B. Moss\'e's unilateral recognizability theorem. We also provide an algorithm for deciding the unilateral non-recognizability of a given primitive substitution.
Generic point equivalence and Pisot numbersMay 10 2019Let $\beta >1$ be an integer or generally a Pisot number. Put $T(x) = \{ \beta x \}$ on $[0,1]$ and let $S: [0,1]\to [0,1]$ be a piecewise linear transformation whose slopes have the form $\pm \beta^m$ with positive integers $m$. We give sufficient conditions ... More
Reversible Nets of PolyhedraJul 02 2016An example of reversible (or hinge inside-out transformable) figures is the Dudeney's Haberdasher's puzzle in which an equilateral triangle is dissected into four pieces, then hinged like a chain, and then is transformed into a square by rotating the ... More
A candidate of a type-2 QSO at z=0.9: Large X-ray absorption with a strong broad-H-alpha emission lineNov 02 2001Deep hard X-ray and near infrared observations of a type-2 radio-quiet QSO candidate at z=0.9, AXJ08494+4454, are reported. The 0.5-10keV Chandra X-ray Observatory spectrum of AXJ08494+4454 is hard, and is explained well with a power-law continuum absorbed ... More
On nearly linear recurrence sequencesJul 29 2016A nearly linear recurrence sequence (nlrs) is a complex sequence $(a_n)$ with the property that there exist complex numbers $A_0$,$\ldots$, $A_{d-1}$ such that the sequence $\big(a_{n+d}+A_{d-1}a_{n+d-1}+\cdots +A_0a_n\big)_{n=0}^{\infty}$ is bounded. ... More