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Keita Nakayama,Masataka Sakane,Susumu Ejima,Daisuke Ito,Tomofumi Nishino,Sou Kitajima,Masashi Yamazaki 대한척추외과학회 2015 Asian Spine Journal Vol.9 No.6
Study Design: Prospective experimental study on humans. Purpose: To determine whether postural differences during a low-speed impact are observed in the sagittal and axial views, particularly in a relaxed state. Overview of Literature: Three-dimensional motion capture systems have been used to analyze posture and head-neck-torso kinematics in humans during a simulated low-speed impact, yet little research has focused on the axial view. Since a seatbelt asymmetrically stabilizes a driver’s right shoulder and left lower waist into the seat, it potentially creates movement in the axial view. Methods: Three healthy adult men participated in the experimental series, which used a low-speed sled system. The acceleration pulse created a full sine shape with a maximum acceleration of 8.0 m/s2 at 500 ms, during which the kinematics were evaluated in relaxed and tensed states. The three-dimensional motion capture system used eight markers to record and analyze body movement and head-neck-torso kinematics in the sagittal and axial views during the low-speed impact. Head and trunk rotation angles were also calculated. Results: Larger movements were observed in the relaxed than in the tensed state in the sagittal view. The cervical and thoracic spine flexed and extended, respectively, in the relaxed state. In the axial view, larger movements were also observed in the relaxed state than in the tensed state, and the left shoulder rotated. Conclusions: During simulated frontal impact, the rotation angle between the head and trunk was significantly larger in the relaxed state. Therefore, we recommend also observing movement in the axial view during impact tests.
Kazuhiko Kinoshita,Kazuki Ginnan,Keita Kawano,Hiroki Nakayama,Tsunemasa Hayashi,Takashi Watanabe 한국통신학회 2020 한국통신학회 APNOMS Vol.2020 No.09
In recent years, LTE system with unlicensed bands is proposed. It can achieve not only to boost the capacity of cellular networks but also to use unlicensed bands effectively since LTE can achieve better spectrum efficiency than Wi-Fi. However, when LTE is introduced into an environment where Wi-Fi access points are already deployed, significant interference may be caused to Wi-Fi. Therefore, the coexistence of LTE and Wi-Fi with unlicensed bands is the problem. In this paper, we assume an environment where LTE base stations and Wi-Fi access points are deployed high-densely with unlicensed bands and co-channel interference frequently is caused. Then, we aim to enhance the average user throughput and its fairness through a centralized control of LTE and Wi-Fi. Specifically, we propose a channel assignment method and a users’ access system selection method using GA. The proposed method enhances both the average user throughput and the fairness of user throughput compared with conventional static channel assignment methods.
Risk Factors for Loosening of S2 Alar Iliac Screw: Surgical Outcomes of Adult Spinal Deformity
Iijima Yasushi,Kotani Toshiaki,Sakuma Tsuyoshi,Nakayama Keita,Akazawa Tsutomu,Kishida Shunji,Muramatsu Yuta,Sasaki Yu,Ueno Keisuke,Asada Tomoyuki,Sato Kosuke,Minami Shohei,Ohtori Seiji 대한척추외과학회 2020 Asian Spine Journal Vol.14 No.6
Study Design: Retrospective study.Purpose: To determine the risk factors for S2 alar iliac (S2AI) screw loosening and its association with lumbosacral fusion in patients with adult spinal deformity (ASD).Overview of Literature: S2AI screws have been widely used for ASD surgery in recent years. However, no studies have analyzed the risk factors for loosening of S2AI screws and its association with lumbosacral fusion.Methods: Cases of 50 patients with ASD who underwent long spinal fusion (>9 levels) with S2AI screws were retrospectively reviewed. Loosening of S2AI screws and S1 pedicle screws and bone fusion at the level of L5–S1 at 2 years after surgery were investigated using computed tomography. In addition, risk factors for loosening of S2AI screws were determined in patients with ASD. Results: At 2 years after surgery, 33 cases (66%) of S2AI screw loosening and six cases (12%) of S1 pedicle screw loosening were observed. In 40 of 47 cases (85%), bone fusion at L5–S1 was found. Pseudarthrosis at L5–S1 was not significantly associated with S2AI screw loosening (19.3% vs. 6.3%, <i>p</i>=0.23), but significantly higher in patients with S1 screw loosening (83.3% vs. 4.9%, <i>p</i><0.001). On multivariate logistic regression analyses, high upper instrumented vertebra (UIV) level (T5 or above) (odds ratio [OR], 4.4; 95% confidence interval [CI], 1.0–18.6; <i>p</i>=0.045) and obesity (OR, 11.4; 95% CI, 1.2–107.2; <i>p</i>=0.033) were independent risk factors for S2AI screw loosening.Conclusions: High UIV level (T5 or above) and obesity were independent risk factors for S2AI screw loosening in patients with lumbosacral fixation in surgery for ASD. The incidence of lumbosacral fusion is associated with S1 screw loosening, but not S2AI screw loosening.