Tip–neck distance ratio as a novel predictor for failure in cephalomedullary nailing of unstable trochanteric fractures (UTF)

The discrete effect on the boundary condition has been a fundamental topic for the lattice Boltzmann method (LBM) in simulating heat and mass transfer problems. In previous works based on the anti-bounce-back (ABB) boundary condition for convection-diffusion equations (CDEs), it is indicated that the discrete effect cannot be commonly removed in the Bhatnagar–Gross–Krook (BGK) model except for a special value of relaxation time. Targeting this point in this paper, we still proceed within the framework of BGK model for two-dimensional CDEs, and analyze the discrete effect on a non-halfway single-node boundary condition which incorporates the effect of the distance ratio. By analyzing an unidirectional diffusion problem with a parabolic distribution, the theoretical derivations with three different discrete velocity models show that the numerical slip is a combined function of the relaxation time and the distance ratio. Different from previous works, we definitely find that the relaxation time can be freely adjusted by the distance ratio in a proper range to eliminate the numerical slip. Some numerical simulations are carried out to validate the theoretical derivations, and the numerical results for the cases of straight and curved boundaries confirm our theoretical analysis. Finally, it should be noted that the present analysis can be extended from the BGK model to other lattice Boltzmann (LB) collision models for CDEs, which can broaden the parameter range of the relaxation time to approach 0.5.

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A multivariate intersection over union of SiamRPN network for visual tracking

The Visual Computer ◽

10.1007/s00371-021-02150-1 ◽

2021 ◽

Author(s):

Zhihui Huang ◽

Huimin Zhao ◽

Jin Zhan ◽

Huakang Li

Keyword(s):

Aspect Ratio ◽

Visual Tracking ◽

Target Location ◽

Coincidence Degree ◽

Distance Ratio ◽

Geometric Factors ◽

Fast Motion ◽

Definition Of ◽

Overlap Area ◽

Center Distance

AbstractSiamPRN algorithm performs well in visual tracking, but it is easy to drift under occlusion and fast motion scenes because it uses $$\ell _1$$ ℓ 1 -smooth loss function to measure the regression location of bounding box. In this paper, we propose a multivariate intersection over union (MIOU) loss in SiamRPN tracking framework. Firstly, MIOU loss includes three geometric factors in regression: the overlap area ratio, the center distance ratio, and the aspect ratio, which can better reflect the coincidence degree of target box and prediction box. Secondly, we improve the definition of aspect ratio loss to avoid gradient explosion, improve the optimization performance of prediction box. Finally, based on SiamPRN tracker, we compared the tracking performance of $$\ell _1$$ ℓ 1 -smooth loss, IOU loss, GIOU loss, DIOU loss, and MIOU loss. Experimental results show that the MIOU loss has better target location regression than other loss functions on the OTB2015 and VOT2016 benchmark, especially for the challenges of occlusion, illumination change and fast motion.

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Benefit of lag screw placement by a single- or two-screw nailing system in elderly patients with AO/OTA 31-A2 trochanteric fractures

Journal of International Medical Research ◽

10.1177/03000605211003766 ◽

2021 ◽

Vol 49 (3) ◽

pp. 030006052110037

Author(s):

Fulong Zhao ◽

Lijuan Guo ◽

Xuefei Wang ◽

Yakui Zhang

Keyword(s):

Blood Loss ◽

Elderly Patients ◽

Fracture Healing ◽

Healing Time ◽

Harris Hip Score ◽

Intraoperative Blood Loss ◽

Trochanteric Fractures ◽

Surgical Time ◽

Gamma3 Nail ◽

Intertan Nail

Objective To retrospectively analyze the clinical outcomes of two intramedullary fixation devices, the INTERTAN nail and Gamma3 nail, for treatment of AO/OTA 31-A2 trochanteric fractures in elderly patients. Methods In total, 165 elderly patients underwent treatment for AO/OTA 31-A2 trochanteric fractures in our hospital from June 2017 to June 2018 (INTERTAN group, n = 79; Gamma3 group, n = 86). All patients underwent radiological and clinical investigations and were followed up for an average of 12 months. Age, sex, fracture type, surgical time, intraoperative blood loss, fracture healing time, and complications were compared between the two groups. Results The surgical time was significantly shorter and the intraoperative blood loss volume was significantly lower in the Gamma3 than INTERTAN group (58.2 ± 2.5 vs. 81.7 ± 14.2 minutes and 170 ± 29 vs. 220 ± 16 mL, respectively). However, there were no significant differences in the reduction quality, hospital stay, fracture healing time, Harris hip score, postoperative complications, or 1-year postoperative mortality. Conclusion Both INTERTAN and Gamma3 nails may be effective for surgical treatment of AO/OTA 31-A2 trochanteric fractures in elderly patients. However, the Gamma3 nail was superior to the INTERTAN nail in terms of surgical time and intraoperative blood loss.

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