Kotaro Yamada

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It is well-known that the unit cotangent bundle of any Riemannian manifold has a canonical contact structure. A surface in a Riemannian 3-manifold is called a (wave) front if it is the projection of a Legendrian immersion into the unit cotangent bundle. We shall give easily-computable criteria for a singular point on a front to be a cuspidal edge or a(More)
Gastrointestinal hormones including gastric inhibitory polypeptide (GIP), glucagon-like peptide (GLP)-1, and GLP-2 are secreted immediately after meal ingestion, and GIP and GLP-2 have been shown to regulate bone turnover. We hypothesize that endogenous GLP-1 may also be important for control of skeletal homeostasis. We investigated the role of GLP-1 in the(More)
where Â, B̂, Ĉ, D̂ and h are meromorphic functions on M. Though √ h is a multi-valued function on M, F is well-defined as a PSL(2,C)-valued mapping. A meromorphic map F as in (1.1) is called a null curve if the pull-back of the Killing form by F vanishes, which is equivalent to the condition that the derivative Fz = ∂F/∂z with respect to each complex(More)
The Thomson scattering system in the TST-2 has been upgraded to improve the reliability and accuracy of measurements. The signal intensity increased because of a new high-energy (1.6 J) laser. A large-numericalaperture (N.A.) fiber was tested, and it was found that a 6-m-long fiber can be used without significant transmission loss. With the upgraded system,(More)
Curcumin is a compound derived from the spice turmeric, and is a potent anti-oxidant, anti-carcinogenic, and anti-hepatotoxic agent. We have investigated the acute effects of curcumin on hepatic glucose production. Gluconeogenesis and glycogenolysis in isolated hepatocytes, and gluconeogenetic enzyme activity after 120 min exposure to curcumin were(More)
After Gálvez, Mart́ınez and Milán discovered a (Weierstrass-type) holomorphic representation formula for flat surfaces in hyperbolic 3-space H, the first, third and fourth authors here gave a framework for complete flat fronts with singularities in H. In the present work we broaden the notion of completeness to weak completeness, and of front to p-front. As(More)
We shall introduce the singular curvature function on cuspidal edges of surfaces, which is related to the Gauss-Bonnet formula and which characterizes the shape of cuspidal edges. Moreover, it is deeply related to the behavior of the Gaussian curvature of a surface near cuspidal edges and swallowtails. Introduction LetM be an oriented 2-manifold and f : M →(More)