Foetomaternal alloimmune thrombocytopenia (FMAIT) occurs when maternal antibodies of an antigen-negative mother cause destruction of sensitized foetal platelets. In Caucasian populations, 6-12% of human platelet antigen (HPA)-1a-negative women develop anti-HPA-1a, and the incidence of clinically affected cases is estimated to be 10-20% of immunized women. This study was performed in order to elucidate the rate of maternal immunization, incidence of FMAIT and the likely outcome of the condition in Asians. Excluding two or more pregnancies during the period, serum samples from 24 630 pregnant women, mainly Japanese, were screened for antibodies against platelet alloantigens by means of mixed passive haemagglutination (MPHA) (Anti-HPA-MPHA, Olympus, Tokyo). Antibodies were detected in 0.91% (223/24 630) of the women's samples and the immunization rate was correlated with the number of pregnancies. Antibody specificity included anti-HPA-4b (49), anti-HPA-5a (three), anti-HPA-5b (168), anti-HPA-4b + 5b (one) and anti-Nak(a) (CD36) (two). No alloimmunization was observed within the HPA-1, HPA-2, HPA-3 or HPA-6 systems. Among HPA-4b- or HPA-5b-negative women, 24% or 14% estimated, respectively, had antibodies and 26% (10/38) or 10% (12/125) of neonates, respectively, born to these mothers developed thrombocytopenia. Two neonates born to mothers having anti-HPA-4b developed generalized purpura. No cases of intracranial bleeding or death due to FMAIT were recorded. Generalized purpura due to FMAIT occurs in one in 9359 (95% CI: 1 in 77 519-1 in 2591) pregnancies solely because of HPA-4b incompatibility.

A new computational scheme integrating multi-center ab initio molecular orbitals for determining total energy and normal vibration of large cluster systems is presented. This method can be used to treat large cluster systems such as solvents by quantum mechanics. The geometry parameters, the total energies, the relative energies, and the normal vibrations for four models of water cluster, the hydrated hydronium ion complex, and the transition state of proton transfer are calculated by the present method and are compared with those obtained by the full ab initio MO method. The results agree very well. The scheme proposed in this article is also intended to be used in modeling computer cluster systems using parallel algorithms.

The driving and damping mechanism of plasma flow is an important issue because flow shear has a significant impact on turbulence in a plasma, which determines the transport in the magnetized plasma. Here we report clear evidence of the flow damping due to stochastization of the magnetic field. Abrupt damping of the toroidal flow associated with a transition from a nested magnetic flux surface to a stochastic magnetic field is observed when the magnetic shear at the rational surface decreases to 0.5 in the large helical device. This flow damping and resulting profile flattening are much stronger than expected from the Rechester–Rosenbluth model. The toroidal flow shear shows a linear decay, while the ion temperature gradient shows an exponential decay. This observation suggests that the flow damping is due to the change in the non-diffusive term of momentum transport.

H a k o z a k i , Fukuoka 81 2, Japan Zr-Hf interdiffusions were carried out at 1350" to 1520°C for p o l y c r y s t a l l i n e t e t r a g o n a l s o l i d s o l u t i o n s of l4CeO2.86(Zrl-,Hf,)O2 with X = 0.02 and 0.10. Lattice and grain-boundary interdiffusion parameters were calculated from the concentration distributions by using Oishi and Ichimura's equation. Lattice interdiffusion coefficients were described by D = 3.0 X 1w exp[-623 (kJ/mol)/RT] cmz/s and grain-boundary interdiffusion parameters by SD' = 0.29 exp[-506 (kJ/mol)/RT] cm3/s. The cation diffusivity was lower than the anion diffusivity. The results were compared with diffusivities in the fluorite-cubic solid solution. The critical grain radii for stabilization of the tetragonal phase in Ce02-doped ZrOz were 11 and 6 pm for the solutions with 2 and 10 mol% HfOz substitution, respectively, both of which are much greater than in the Yz03-doped Zr02 solid solution. [