Shuttling a single charge across a one-dimensional array of silicon quantum dots.

Significant advances have been made towards fault-tolerant operation of silicon spin qubits, with single qubit fidelities exceeding 99.9%, several demonstrations of two-qubit gates based on exchange coupling, and the achievement of coherent single spin-photon coupling. Coupling arbitrary pairs of spatially separated qubits in a quantum register poses a significant challenge as most qubit systems are constrained to two dimensions with nearest neighbor connectivity. For spins in silicon, new methods for quantum state transfer should be developed to achieve connectivity beyond nearest-neighbor exchange. Here we demonstrate shuttling of a single electron across a linear array of nine series-coupled silicon quantum dots in ~50 ns via a series of pairwise interdot charge transfers. By constructing more complex pulse sequences we perform parallel shuttling of two and three electrons at a time through the array. These experiments demonstrate a scalable approach to physically transporting single electrons across large silicon quantum dot arrays.

The efficacy of selenium dioxide as a selenium supplement for dairy cattle.

The efficacy of selenium dioxide (SeO2) was similar to sodium selenate (Na2SeO4 x 10H2O), in terms of increasing and maintaining blood Se concentrations, when administered orally twice daily to give 0.64 mg of Se/day to grazing dairy cows for 55 days.

Surface quality of gypsums when poured against alginates.

Alginate impression materials are universally accepted for the fabrication of dental casts. Since casts reflect a direct link between the patient and the dentist, it is imperative that their surfaces be of highest quality. This study assesses the quality of dental cast surfaces when poured against alginate impression materials. A standardized system previously designed by the authors allowed the evaluations of 16 different gypsums poured against 32 different alginate surfaces, including a plexiglass control surface. Five hundred and twelve gypsum surfaces were produced and evaluated for quality in the following manner: 1) assessed visually with the aid of photomicrographs for surface smoothness; 2) evaluated by a modified Vickers scratch test for surface hardness. The results indicate that certain gypsum-alginate combinations provide superior surfaces with respect to hardness and smoothness, while other combinations suggest a high degree of incompatibility.

Pelagic paralysis.

Three conditions that may occur after consumption of seafood--puffer fish poisoning, ciguatera, and paralytic shellfish poisoning--are caused by a group of poisons that block voltage-gated sodium channels in myelinated and non-myelinated nerves. The conditions cannot be distinguished clinically and so constitute an entity for which the name pelagic paralysis is proposed. Variations in the clinical features can be accounted for by large differences in the amount of toxin present in the seafood.