Stability of degenerate abelian varieties

We compactify canonically the moduli scheme of abelian schemes over Z[+_N,1/N] by introducing the noncommutative level structures. Any degenerate abelian scheme on the boundary of the compactification is a singular one among our models - projectively stable quasi-abelian schemes. We prove that a degenerate abelian scheme has Kempf-stable Hilbert points if and only if it is a projectively stable quasi-abelian scheme.     

A wet method of carbon extraction from iron artifacts for14C age measurement with AMS

Japanese iron artifacts contain a small amount of charcoal which was used in manufacturing. We developed a wet method of carbon extraction from the iron samples for AMS radiocarbon dating. The method consists of dissolution of iron with a Cu²⁺ solution and dissolution of deposited Cu in HCl. High extraction yields (80–90%) and low contamination by modern carbon were achieved by the wet method.     

Unusual evolution of the conduction-electron state in CexLa1-xB6 from non-Fermi liquid to Fermi liquid

We report unusual evolution of the conduction-electron state in the localized f electron system CexLa1-xB6 from normal electron state to heavy Fermi liquid (FL) state through local FL and non-FL states with increasing Ce concentration and/or with increasing magnetic field. The effective mass of quasiparticle or the coefficient A of T2 term of resistivity is found to increase divergently near the boundary between FL state and non-FL state. The features of the non-FL state are also different from those of the typical non-FL systems previously observed or theoretically predicted.     

Curie temperatures of CoPt ultrathin continuous films

The effects of layer thickness and thermal annealing on Curie temperature have been studied for CoPt ultrathin continuous layers in AlN/CoPt multilayer structures. It is found that there exists a critical thickness below which Curie temperature rapidly decreases due to the loss of spin-spin interactions in the vicinity of interface. After high temperature annealing, the in-plane lattice constant of CoPt film is increased and the exchange coupling parameter is decreased. Consequently, Curie temperatures decrease for some films with large thickness, compared with as-deposited state. Upon annealing at 600?^°C, CoPt undergoes ordering transformation, which also contributes to the degradation of the Curie temperature. However, when the CoPt film thickness is below 2?nm, the Curie temperature is increased after annealing. Especially for 1?nm thick film, the Curie temperature is strikingly increased from 173?^°C to 343?^°C after annealing at 600?^°C. This effect is attributed to the out-of-plane lattice deformation of CoPt thin layers in AlN/CoPt multilayer structures.     

Electron cyclotron heating in the WT-1 tokamak

When a high power microwave is injected into a tokamak plasma, the intensities of microwave radiations emitted from the plasma and those of impurity lines are increased. Such increases are observed only when the electron cyclotron resonance field is present in the torus. The upper hybrid resonance heating is also observed near the plasma surface.     

Absorption cross sections for antiprotons on carbon, aluminum and copper at 485 and 597 MeV/c

Absorption cross sections for antiprotons on C, Al and Cu have been measured by a transmission method at 485 and 597 MeV/c. Nuclei are shown to be black to antiprotons at these momenta. Using the available data up to 280 GeV/c, the momentum dependence of the absorption cross sections is investigated. Empirically, a simple expression σ_abs = γ(p/p₀)^−β, with β and γ constants and p₀ = 1 GeV/c, gives a good account of the data in a remarkably wide momentum range, 0.5–280 GeV/c.     

Electron-hole coupled plasma mode in the magnetoreflection of graphite under high magnetic fields

A new structure which cannot be explained by any transitions between Landau levels was found in the far-infrared magnetoreflection spectra in graphite under high magnetic fields up to 45 T. The photon energy at which this structure is observed tends to zero at zero field, and it increases superlinearly with increasing magnetic field. The origin of this mode is interpreted in terms of the electron-hole coupled plasma which has never been observed in other substances before.