#### Filter Results:

- Full text PDF available (7)

#### Publication Year

1987

2009

- This year (0)
- Last 5 years (0)
- Last 10 years (7)

#### Publication Type

#### Co-author

#### Journals and Conferences

Learn More

- Naoyuki Koike
- 2009

First we show that a curvature-adapted proper complex equifocal submanifold is a principal orbit of a Hermann type action under certain condition. Next we show that a proper complex equifocal submanifold is curvature-adapted under certain condition.

Mutagenicity of five benzene metabolites was examined by a fluctuation test modified by Gatehouse. The test was performed by using Salmonella typhimurium TA100 with or without a metabolic activation system. Catechol showed mutagenic activity with and without a metabolic activation system in the fluctuation test. Hydroxyhydroquinone, phenol, hydroquinone and… (More)

- Naoyuki Koike
- 2009

In this paper, we prove that there exists no equifocal submanifold with non-flat section in irreducible simply connected symmetric spaces of compact type and rank greater than one. As its application, it is shown that all polar actions on the symmetric spaces are hyperpolar.

Mutagenicity of nine epoxy resin hardeners was examined by a fluctuation test modified by Gatehouse. The test was performed by using Salmonella typhimurium TA98 with a metabolic activation system. In our laboratory, the results of the fluctuation test were compared with the results obtained by the previously mentioned Ames preincubation method. Six out of… (More)

- Naoyuki Koike
- 2009

In this paper, we investigate the mean curvature flows having an equifocal submanifold in a symmetric space of compact type and its focal submanifolds as initial data. The investigation is performed by investigating the lifts of the submanifolds and the flows to an (infinite dimensional separable) Hilbert space through a Riemannian submersion of the Hilbert… (More)

- Naoyuki Koike
- 2008

In a symmetric space of non-compact type, the notion of a complex equifocal submanifold (with flat section) is defined. It is conjectured that this notion coincides with the notion of an isoparametric submanifold with flat section. As a subclass of a complex equifocal submanifold, the notion of a proper complex equifocal submanifold is defined. In this… (More)

- Naoyuki Koike
- 2008

In this paper, we investigate curvature-adapted and proper complex equifocal submanifolds in a symmetric space of non-compact type. The class of these submanifolds contains principal orbits of Hermann type actions as homogeneous examples and is included by that of curvature-adapted and isoparametric submanifolds with flat section. First we introduce the… (More)

- Naoyuki Koike
- 2009

In this paper, we investigate the mean curvature flows having an equifocal submanifold in a symmetric space of compact type and its focal submanifolds as initial data. The investigation is performed by investigating the lifts of the submanifolds and the flows to an (infinite dimensional separable) Hilbert space through a Riemannian submersion of the Hilbert… (More)

- Naoyuki Koike
- 2009

In this paper, we first investigate the geometry of the orbits of the isotropy action of a semi-simple pseudo-Riemannian symmetric space by investigating the complexified action. Next we investigate the geometry of the orbits of a Hermann type action on a semi-simple pseudo-Riemannian symmetric space. By considering two special Hermann type actions on a… (More)

- ‹
- 1
- ›