Depinning phase transition of antiferromagnetic skyrmions with quenched disorder.

Antiferromagnetic skyrmions are considered to be promising information carriers due to their attractive properties. Therefore, the pinning phenomenon of antiferromagnetic skyrmions is of great significance. With the Landau-Lifshitz-Gilbert equation, we simulate the nonstationary dynamic behaviors of skyrmions driven by currents in a chiral antiferromagnetic thin film with quenched disorder. Based on the dynamic scaling forms, the critical current and static and dynamic critical exponents of the depinning phase transition are accurately determined. A theoretical analysis using Thiele's approach is presented in comparison with the numerical simulation. Unlike the ferromagnetic skyrmions, the critical current of the antiferromagnetic skyrmions is very sensitive to a small nonadiabatic coefficient. This is important for manipulating antiferromagnetic skyrmions and designing novel information processing devices.

[Clinical retrospective control study of single-port laparoendoscopic and multi-port laparoscopic ovarian cystectomy].

Objective: To investigate clinical outcomes of laparoendoscopic single-site ovarian cystectomy compared with traditional multi-port laparoscopic ovarian cystectomy. Methods: Data of 81 patients with ovarian cystectomy from January 2016 to May 2017, the single-site group (n=40) and the multi-port group (n=41) in Peking Union Medical College Hospital were retrospectively collected. The outcomes of single-site and multi-port groups were analyzed and compared, including: postoperative fever, operation time, blood loss, hemoglobin change, surgical complications, postoperative pain score, postoperative analgesic requirements, body image scale and cosmetic score, length of hospital stay, postoperative total cost. Results: No complication was found in two groups. No difference was found in postoperative fever, blood loss, hemoglobin change, postoperative pain score, length of hospital stay, and total cost between the two groups (all P>0.05). Operation time was (50±20) minutes in single-site group, and (40±15) minutes in multi-port group; postoperative analgesic requirements was 28%(11/40) in single-site group, and 7%(4/41) in multi-port group; cosmetic score was 22.6±2.6 in single-site group, and 17.3±2.6 in multi-port group; body image scale was 5.7±1.2 in single-site group, and 6.2±1.2 in multi-port group; these four clinical parameters were statistical differences (all P<0.05). Conculsion: Laparoendoscopic single-site ovarian cystectomy is feasible and safe, although it could't relieve the postoperative pian, it do offer a higher cosmetic satisfaction.