Hybrid dynamics of H\'enon mappings

For studying the meromorphic degeneration of complex dynamics, the theory of hybrid spaces, introduced by Boucksom, Favre and Jonsson, is known to be a strong tool. In this paper, we apply this theory to the dynamics of H\'enon maps. For a family of H\'enon maps $\{H_t\}_{t\in\mathbb{D}^*}$ that is parametrized by a unit punctured disk and meromorphically degenerates at the origin, we show that as $t\to 0$, the family of the invariant measures $\{\mu_t\}$ "weakly converges" to a measure on the Berkovich affine plane associated to the non-archimedean H\'enon map determined by the family $\{H_t\}_t$. We also calculate the limit of their Lyapunov exponents.Comment: 19 page

Hydrogen Sensors Using Nitride-Based Semiconductor Diodes: The Role of Metal/Semiconductor Interfaces

In this paper, I review my recent results in investigating hydrogen sensors using nitride-based semiconductor diodes, focusing on the interaction mechanism of hydrogen with the devices. Firstly, effects of interfacial modification in the devices on hydrogen detection sensitivity are discussed. Surface defects of GaN under Schottky electrodes do not play a critical role in hydrogen sensing characteristics. However, dielectric layers inserted in metal/semiconductor interfaces are found to cause dramatic changes in hydrogen sensing performance, implying that chemical selectivity to hydrogen could be realized. The capacitance-voltage (C–V) characteristics reveal that the work function change in the Schottky metal is not responsible mechanism for hydrogen sensitivity. The interface between the metal and the semiconductor plays a critical role in the interaction of hydrogen with semiconductor devises. Secondly, low-frequency C–V characterization is employed to investigate the interaction mechanism of hydrogen with diodes. As a result, it is suggested that the formation of a metal/semiconductor interfacial polarization could be attributed to hydrogen-related dipoles. In addition, using low-frequency C–V characterization leads to clear detection of 100 ppm hydrogen even at room temperature where it is hard to detect hydrogen by using conventional current-voltage (I–V) characterization, suggesting that low-frequency C–V method would be effective in detecting very low hydrogen concentrations

On a family of quotients of Fermat curves

Let Fx be the N-th Fermat curve defined by the equation: ux+vn=1. For a pair (r, s) of positive integers such that r+s≦N-1 and g.c.d (r, s, N)=1, we denote by F(r, s) the quotient of Fx defined by the equation: ..

キノコの成分研究(第28報)エゾハリタケのステロール成分について

Eleven sterols were isolated from the fruiting bodies of Climacodon septentrionalis (Fr.) Karst. (Climacodontaceae) and identified as (22E)-ergosta-5,7,9(11),22-tetraen-3β-ol (1), ergosterol (2), ergosta-5,7-dien-3β-ol (3), (22E)-ergosta-5,8,22-trien-3β-ol (4), (22E)-ergosta-7,22-dien-3β-ol (5), ergost-7-en-3β-ol (6), ergosterol peroxide (7), 5α,8α-epidioxy-(22E)-ergosta-6,9(11),22-trien-3β-ol (8), 5α,6α-epoxy-(22E)-ergosta-8(14),22-diene-3β,7α-diol (9), 6β-methoxy-(22E)-ergosta-7,22-diene-3β,5α-diol (10), and 6β-methoxy-(22E)-ergosta-7,22-diene-3β,5α,9α-triol (11). Their structures were determined on the basis of spectral data. Compounds 1-11 have been isolated from the fruiting bodies of C. septentrionalis for the first time