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Yoshifumi Futaana

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Erratum to "Cobordisms of maps with singularities of given class"

Ando Yoshifumi
09 Nov 2009 math.GT math.AT arxiv.org/abs/0911.1588

We correct the proof in the unoriented case of Theorem 1.2 in the paper "Cobordisms of maps with singularities of given class"

Cobordisms of maps with singularities of a given class

Ando Yoshifumi
29 Jul 2007 math.GT arxiv.org/abs/0707.4329

Let P be a connected smooth p-manifold. We describe the group of all cobordism classes of smooth maps of n-manifolds to P with singularities of a given $cal K$-invariant class in terms of certain stable homotopy groups by applying the relative homotopy principle on the existence level. We also deal with the oriented version and construct a classifying space to which this oriented cobordism group is represented as the set of homotopy classes of P in the codimension n<p and n\geqq p\geqq 2.

Smooth maps with singularities of bounded K-codimensions

Ando Yoshifumi
01 Apr 2007 math.GT arxiv.org/abs/0704.0115

We will prove the relative homotopy principle for smooth maps with singularities of a given {\cal K}-invariant class with a mild condition. We next study a filtration of the group of homotopy self-equivalences of a given manifold P by considering singularities of non-negative {\cal K}-codimensions.

Cobordisms of maps without prescribed singularities

Ando Yoshifumi
12 Dec 2004 math.GT arxiv.org/abs/math/0412234

Let $N$ and $P$ be smooth closed manifolds of dimensions $n$ and $p$ respectively. Given a Thom-Boardman symbol $I$, a smooth map $f:N\to P$ is called an $\Omega^{I}$-regular map if and only if the Thom-Boardman symbol of each singular point of $f$ is not greater than $I$ in the lexicographic order. We will represent the group of all cobordism classes of $\Omega^{I}$-regular maps of $n$-dimensional closed manifolds into $P$ in terms of certain stable homotopy groups. As an application we will study the relationship among the stable homotopy groups of spheres, the above cobordism group and higher singularities.

The homotopy principle in the existence level for maps with only singularities of types A, D and E

Ando Yoshifumi
17 Nov 2004 math.GT arxiv.org/abs/math/0411399

Let N and P be smooth manifolds of dimensions n and p (n \geq p \geq 2) respectively. Let \Omega(N,P) denote an open subspace of J^{infty}(N,P) which consists of all regular jets and jets with prescribed singularities of types A_{i}, D_{j} and E_{k}. An \Omega-regular map f:N \to P refers to a smooth map having only singularities in \Omega(N,P) and satisfy the transversality condition. We will prove the homotopy principle in the existence level for \Omega-regular maps.

A homotopy principle for maps with prescribed Thom-Boardman singularities

Ando Yoshifumi
11 Sep 2003 math.GT arxiv.org/abs/math/0309204

Let N and P be smooth manifolds of dimensions n and p (n>=p>=2). Let Omega^{I}(N,P) denote an open subspace of J(N,P) which consists of all Boardman submanifolds Sigma^{J}(N,P) with J=< I in the lexicographic order. We will prove the homotopy principle in the existence level for Omega^{I}(N,P).

Existence theorems of fold-maps

Ando Yoshifumi
08 Sep 2003 math.GT arxiv.org/abs/math/0309141

A smooth map having only fold singularities is called a fold-map. We will give effective conditions for a continuous map to be homotopic to a fold-map from the viewpoint of the homotopy principle.

ASCA Discovery of an X-ray Pulsar in the Error Box of SGR1900+14

Hurley K., Li P., Kouveliotou C., Murakami T., Ando M., Strohmayer T., van Paradijs J., Vrba F., Luginbuhl C., Yoshida A.
24 Nov 1998 astro-ph arxiv.org/abs/astro-ph/9811388

We present a 2 - 10 keV ASCA observation of the field around the soft gamma repeater SGR1900+14. One quiescent X-ray source was detected in this observation, and it was in the SGR error box. In 2 - 10 keV X-rays, its spectrum may be fit by a power law with index -2.2, and its unabsorbed flux is 9.6 x 10^-12 erg cm^-2 s^-1. We also find a clear 5.16 s period. The properties of the three well-studied soft gamma repeaters are remarkably similar to one another, and provide evidence that all of them are associated with young, strongly magnetized neutron stars in supernova remnants.

Temperature- and magnetic-field-dependent thermal conductivity of pure and Zn-doped Bi_{2}Sr_{2}CaCu_{2}O_{8+\delta} single crystals

Ando Yoichi, Takeya J., Abe Yasushi, Nakamura K., Kapitulnik A.
16 Dec 1998 cond-mat.supr-con arxiv.org/abs/cond-mat/9812265

The thermal conductivity \kappa of Bi-2212 is measured in pure and Zn-doped crystals as a function of temperature and magnetic field. The in-plane resistivity is also measured on the identical samples. Using these data, we make a crude estimate of the impurity-scattering rate \Gamma of the pure and the Zn-doped crystals. Our measurement show that the "plateau" in the \kappa(H) profile is not observed in the majority of our Bi-2212 crystals, including one of the cleanest crystals available to date. The estimated values of \Gamma for the pure and Zn-doped samples allow us to compare the \kappa(H) data with the existing theories of the quasiparticle heat transport in d-wave superconductors under magnetic field. Our analysis indicates that a proper inclusion of the quasiparticle-vortex scattering, which is expected to play the key role in the peculiar behavior of the \kappa(H), is important for a quantitative understanding of the QP heat transport in the presence of the vortices.

Normal-state magnetotransport in La_{1.905}Ba_{0.095}CuO_{4} single crystals

Abe Yasushi, Ando Yoichi, Takeya J., Tanabe H., Watauchi T., Tanaka I., Kojima H.
21 Dec 1998 cond-mat.supr-con arxiv.org/abs/cond-mat/9812335

The normal-state magnetotransport properties of La_{2-x}Ba_{x}CuO_{4} single crystals with x=0.095 are measured; at this composition, a structural transition to a low-temperature-tetragonal (LTT) phase occurs without suppression of superconductivity. None of the measured properties (in-plane and out-of-plane resistivity, magnetoresistance, and Hall coefficient) shows any sudden change at the LTT phase transition, indicating that the occurrence of the LTT phase does not necessarily cause an immediate change in the electronic state such as the charge-stripe stabilization.