Nonlocal Spin Correlation as a Signature of Ising Anyons Trapped in Vacancies of the Kitaev Spin Liquid.

In the Kitaev chiral spin liquid, Ising anyons are realized as Z_{2} fluxes binding Majorana zero modes, which, however, are thermal excitations with finite decay rates. On the other hand, a lattice vacancy traps a Z_{2} flux even in the ground state, resulting in the stable realization of a Majorana zero mode in a vacancy. We demonstrate that spin-spin correlation functions between two vacancy sites exhibit long-range correlation arising from the fractionalized character of Majorana zero modes, in spite of the strong decay of bulk spin correlations. Remarkably, this nonlocal spin correlation does not decrease as the distance between two vacancy sites increases, signaling Majorana teleportation. Furthermore, we clarify that the nonlocal correlation can be detected electrically via the measurement of nonlocal conductance between two vacancy sites, which is straightforwardly utilized for the readout of Majorana qubits. These findings pave the way to the measurement-based quantum computation with Ising anyons trapped in vacancies of the Kitaev spin liquid.

The true distal posterior inferior cerebellar artery aneurysm: clinical characteristics and strategy for treatment.

OBJECTIVE: A series of aneurysms located at the 4 (th) or 5 (th) segment of the posterior inferior cerebellar artery (PICA) has not been previously reported in the literature. We report six such cases and analyze their clinical characteristics and outcomes from three different treatment strategies. MATERIAL AND METHODS: We reviewed six patients with a diagnosis of distal PICA aneurysm. The following data were analyzed: age, sex, aneurysm size, Hunt-Hess grade at presentation, angiographic characteristics, and clinical treatment outcome determined by Glascow outcome scores (GOS). Treatments performed included clipping and wrapping, sacrificing the parent arteries of the aneurysms, and selective coiling. RESULTS: Six patients (5 females, 1 male; mean age: 61.2 years; mean aneurysm size: 6.2 mm) presented at our facility with subarachnoid hemorrhage (SAH) caused by aneurysm rupture. Two patients presented with Hunt-Hess grades 4 and 5; all others were in Hunt-Hess grades 2 or 3. One patient died before surgery. Treatment outcomes of the surviving five patients were as follows: three patients had GOS of 5, one improved by operation, and another died from re-bleeding after selective coiling. CONCLUSION: Surgery for the true distal PICA aneurysm results in good clinical outcomes. Clipping or wrapping should be considered as the first choice for treatment, and sacrificing the parent artery of the distal PICA aneurysm is relatively safer than selective coiling. The type of parent artery and particularly the collateralization of its distal part should be considered as an essential factor to take into consideration when choosing a treatment strategy.

[Clinical application of three-dimensional ultrasound imaging as intraoperative navigation for liver surgery].

Intraoperative hepatic ultrasonography provides a great deal of information about tumor location and vascular anatomy in the liver, and is an indispensable procedure for hepatic resection. However, an accurate three-dimensional understanding of ultrasound (US) images depends on the operator's skill and experience, as the original display is two dimensional. We developed a new three-dimensional US (3D-US) image processing method by application of the intensity projection method to US. The minimum and maximum intensity projection can display the arrangement of blood vessels (hepatic veins and portal veins) and hyperechoic regions, respectively. The intensity projection from several points of view can reconstruct 3D imaging by cine-display. Moving a probe manually, images are taken and processed on a real-time basis (in about 10 seconds). 3D-US was used in 24 patients undergoing hepatic resection, and allowed easy visualization of the tumors and vascular anatomy. It is considered to be an efficient and safe navigation system in liver surgery.