Assembly and coherent control of a register of nuclear spin qubits.

The generation of a register of highly coherent, but independent, qubits is a prerequisite to performing universal quantum computation. Here we introduce a qubit encoded in two nuclear spin states of a single 87Sr atom and demonstrate coherence approaching the minute-scale within an assembled register of individually-controlled qubits. While other systems have shown impressive coherence times through some combination of shielding, careful trapping, global operations, and dynamical decoupling, we achieve comparable coherence times while individually driving multiple qubits in parallel. We highlight that even with simultaneous manipulation of multiple qubits within the register, we observe coherence in excess of 105 times the current length of the operations, with [Formula: see text] seconds. We anticipate that nuclear spin qubits will combine readily with the technical advances that have led to larger arrays of individually trapped neutral atoms and high-fidelity entangling operations, thus accelerating the realization of intermediate-scale quantum information processors.

Spatio-Temporal Flexibility of Attention Inferred from Drivers' Steering Movements.

Participants attempted to center a cursor on a video display of a winding roadway with a rate control system. Fourier analysis of their steering movements in response to sinusoidal perturbations of the roadway revealed how much attention they allocated to different roadway preview locations. We compared a full 1.0 s of preview with preview restricted to a narrow slit around 0.3 s or 0.6 s. Participants were able to flexibly shift their attention to either slit. However, they performed better in terms of root-mean-squared error, velocity error, and acceleration error with the fuller view. They concentrated their attention over a range from 0.1 s to 0.3 s of preview in a manner qualitatively consistent with Miller's optimal control model.

Meta-analysis of randomized controlled trials on the risk of bleeding with dabigatran.

Dabigatran is a univalent low-molecular-weight direct thrombin inhibitor that has been developed as an alternative to vitamin K antagonists (VKAs). However, uncertainty remains regarding dabigatran's safety profile with respect to bleeding. Our objective was to compare the risk of bleeding and all-cause mortality of dabigatran with that of VKAs in a systematic review and meta-analysis of randomized controlled trials (RCTs). We systematically searched MEDLINE, Embase, and the Cochrane Library of clinical trials to identify RCTs comparing the bleeding risk of dabigatran (150 mg twice daily) with that of VKAs. Included RCTs had treatment duration ≥90 days and were published in English or French. Data were meta-analyzed using random-effects models. Five RCTs (n = 20,332) were included in our systematic review. Study populations consisted of patients with atrial fibrillation (n = 18,615) and venous thromboembolism (n = 7,998). When data were pooled across the 4 RCTs (n = 17,466) without overlapping populations, dabigatran was not associated with an increased risk of major bleeding compared with VKAs (relative risk [RR] 0.92, 95% confidence interval [CI] 0.81 to 1.05). Dabigatran was associated with a decreased risk of intracranial bleeding (RR 0.40, 95% CI 0.27 to 0.59) but an increased risk of gastrointestinal bleeding (RR 1.51, 95% CI 1.23 to 1.84). Dabigatran was also associated with a trend toward decreased all-cause mortality (RR 0.90, 95% CI 0.80 to 1.01). In conclusion, results suggest that dabigatran has a favorable safety profile with respect to bleeding compared with VKAs.