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In this paper, an unmanned aerial vehicle (UAV) nonorthogonal multiple access (NOMA) system operating in millimeter-wave (mmWave) communications under the aid of multiple reconfigurable intelligent surfaces (RISs) is determined. Specifically, two NOMA users receive messages from UAV via both UAV-RISs-user and UAV-user links using mmWave communications. The closed-form expressions of outage probabilities (OPs) and achievable data rates (ADRs) are successfully derived over Nakagami-m fading channels to investigate the performance of the RISs aided UAV-NOMA-mmWave system. Computer simulations are provided to validate the derived expressions. Numerical results observe that by utilizing RISs, the OPs and ADRs performance of UAV-NOMA-mmWave system is significantly improved in comparison with the case without RISs. More specifically, even with high altitude of UAV (300 m) and high carrier frequency (50 GHz), the OPs of UAV-NOMA-mmWave system with RISs are remarkably lower than those without RISs. Meanwhile, the ADRs with RISs are only higher than those without RISs in low transmit power of UAV. In high transmit power of UAV, ADRs with and without RISs are similar due to the NOMA characteristics. Besides the distances and carrier frequency, the effects of other parameters such as the position of RISs, the number of reflecting elements (REs), and the altitude of UAVs are clarified to obtain the system behaviors. [ABSTRACT FROM AUTHOR]

Background: The aim of this study was to assess the efficacy of our simple landmark technique for laparoscopic detorsion and the Ladd's procedure (lap‐Ladd) for malrotation with midgut volvulus in neonates and to identify the risk factors for reoperation after the lap‐Ladd. Methods: We conducted a retrospective chart review of 42 patients after lap‐Ladd for malrotation between April 2017 and June 2019. Information regarding patient status and intraoperative and postoperative data were analyzed. Results: Thirty‐one patients had volvulus (73.8 %), while 11 patients did not (26.2%). The median age and weight between the two groups at operation were 9 days (range, 3–28 days), 3.2 kg (range, 2–8 kg) and 6 days (range, 2–11), 2.9 kg (range, 2–3.8 kg), respectively. The operative time was significantly shorter in patients with volvulus compared to those without (60 vs 105 min, P = 0.002). Two cases were converted to open surgery because of ischemic changes of the total small intestine during surgery. Reoperation was required in two patients with volvulus (due to adhesive small bowel obstruction and recurrent volvulus). There was no significant predictive factor for reoperation after the lap‐Ladd procedure. Conclusion: Our simple landmark lap‐Ladd procedure demonstrated feasibility and good short‐term outcomes in neonates with malrotation, regardless of the presence or absence of volvulus. [ABSTRACT FROM AUTHOR]

In this paper, a novel compact multipleinput multiple-output (MIMO) antenna with the size of 26 mm × 60 mm × 1.6 mm for ultra-wide band (UWB) applications is proposed. The proposed MIMO antenna consists of two single UWB antennas and a stub placed between the two antennas to reduce the mutual coupling. The proposed antenna achieves the voltage standing wave ratio (VSWR) less than 2 and more than 86% radiation efficiency over the whole band of interest. Performance of the antenna is examined using both simulation and experiment. [ABSTRACT FROM AUTHOR]