Solid-state qubits with current-controlled coupling.

The ability to switch the coupling between quantum bits (qubits) on and off is essential for implementing many quantum-computing algorithms. We demonstrated such control with two flux qubits coupled together through their mutual inductances and through the dc superconducting quantum interference device (SQUID) that reads out their magnetic flux states. A bias current applied to the SQUID in the zero-voltage state induced a change in the dynamic inductance, reducing the coupling energy controllably to zero and reversing its sign.

The incidence of insulin-dependent diabetes mellitus in urban districts of Shanghai (1989-1993).

A retrospective study on the incidence of insulin-dependent diabetes mellitus (IDDM) among children aged 0-14 years was carried out from 1989-1993 in urban Shanghai, China. The average annual population at risk (0-14 yr) consisted of 1,401,664 children. All the cases were collected from the hospitals (primary source) and from primary and middle schools and kindergartens (second source) with independent validation of case ascertainment. There were 53 IDDM cases from the primary source, 23 from the secondary source, with a total of 58. The ascertainment corrected total number of IDDM cases was 67 by the capture-recapture method. The average crude annual incidence rate was 0.83 [95% confidence interval (CI) 0.61-1.04] and ascertainment corrected incidence rate 0.96 (95% CI 0.80-1.12) per 100,000. Peak incidence fell in 1992 and in the 9 year-old group. The incidence of childhood IDDM in the urban districts of Shanghai was reconfirmed to be the lowest in the world but by comparing the results of former investigations a trend was found of increasing incidence of IDDM.

Etiological investigation of farmer's lung disease: a serological study.

To confirm the main etiological antigen of farmer's lung in Dafeng County, Jiangsu Province, People's Republic of China, precipitins in serum from 30 patients with farmer's lung were tested with several strains of antigens. Reactions against two strains of T.vulgaris were shown in 46.7% and 66.7% of the patients group, which were significantly higher than in the controls, while the percentage of reactions against Faenia rectivirgula and A. fumigates were low in the patients group and had no significant difference with the controls. The results indicate that the main etiological agents were some strains of T. vulgaris. This finding was consistent with the microbiological study of sputum of the patients and moldy hay samples from the working area.