We extend the spinorial geometry techniques developed for the solution of supergravity Killing spinor equations to the kappa symmetry condition for supersymmetric brane probe configurations in any supergravity background. In particular, we construct the linear systems associated with the kappa symmetry projector of M-and type II branes acting on any Killing spinor. As an example, we show that static supersymmetric M2-brane configurations which admit a Killing spinor representing the SU (5) orbit of Spin(10, 1) are generalized almost hermitian calibrations and the embedding map is pseudo-holomorphic. We also present a bound for the Euclidean action of M-and type II branes embedded in a supersymmetric background with non-vanishing fluxes. This leads to an extension of the definition of generalized calibrations which allows for the presence of non-trivial Born-Infeld type of fields in the brane actions.
A crystallographic study was done in the Nd2CuO4-Sr2CuO3 system. Five phases were found in this system; A: Nd2CuO4, B: Nd2SrCu2O6, C: (Nd0.45Sr0.55)3Cu2O6-y
, D: (Nd1-x
Sr
x
)2CuO4-y
, and E: Sr2CuO3. Phases B and C possess Sr3Ti2O7-type structures, and phase D has the same structure as La2CuO4. No superconductivity was observed in any of the above-mentioned phases down to 4.2 K.
A new compound, PrBa2Cu3O
y
, which is isomorphic with YBa2Cu3O
y
, was prepared as single phase. With specimens quenched from 920°C, the oxygen content y was 6.8 ± 0.1 and the ratio of Pr3+ to Pr4+ was 0.4:0.6. With furnace-cooled specimens, the value of y was 7.1 ± 0.1 and the ratio became 0.1:0.9. The average valence of Cu ions was 2.0 ± 0.1 for the former and 2.1 ± 0.1 for the latter. Specimens handled both ways were nonmetallic and nonsuperconducting down to 4.2 K.
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