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Background: Transoral thyroidectomy has superior cosmesis and better postoperative voice outcomes than conventional thyroidectomy. However, it usually requires a steep learning curve and longer operative time. The transoral robotic thyroidectomy (TORT) learning curve has not been well investigated. This study aimed to evaluate the TORT learning curve and factors affecting operative time. Methods: We retrospectively studied 173 consecutive patients who underwent TORT with or without central neck dissection from July 2017 to August 2021. We assessed the TORT learning curve using operative time, complication rate, and surgical success (procedure conversion) rate. The operative time and surgical success rate learning curves were calculated using the cumulative summation (CUSUM) method. Additionally, we analyzed factors affecting operative time in TORT. Results: Total thyroidectomy operative time was significantly longer than those of lobectomy and isthmusectomy (p < 0.001). In correlation analysis, a significantly positive correlation was observed between body mass index (BMI) and operative time (R2 = 0.04, p = 0.025). The TORT learning curve was 52 cases in the CUSUM operative time analysis. In the CUSUM surgical success rate chart, the turning point was the 55th case. Complication and procedure conversion rates were significantly decreased after the learning curve. Conclusions: The CUSUM learning curve of TORT was about 52–55 cases, and the operative time, total complication rate, and procedure conversion decreased significantly after the learning curve. The operative time was associated with the extent of thyroidectomy and BMI. [ABSTRACT FROM AUTHOR]

Objectives: Foreign bodies (FBs) in external auditory canal (EAC) can occur at any age but are especially common in children and adolescents. The aims of the study were to evaluate the clinical characteristics of EAC FBs in children and adolescents and to discuss their proper management. Methods: A retrospective medical chart review was performed on patients who were treated for EAC FBs in a tertiary referral center from January 2007 to December 2017. We investigated the parameters of age, sex, type of FB, sedation method, complications, and removal strategy. Results: Of 284 patients, 176 (62.0%) were male. Peak incidences were noted at the ages of 3 to 6 years and 17 to 18 years. The frequently observed FBs were insects, followed by air-gun pellets, cotton balls, marbles, and earrings. Forty-one (14.4%) EAC FBs were removed with the naked eye, while 243 (85.6%) were removed under microscope in the otolaryngology department. Of these patients, 23 (9.5%) were administered sedatives and 1 (4.1%) needed general anesthesia. During or after the removal procedure, 4 (15.5%) patients had complications of EAC abrasion or laceration (42, 14.8%), and tympanic membrane perforation (2, 0.7%). Conclusions: External auditory canal FB showed a distinct characteristic of incidence regarding age, related to removal strategies. Characteristics of FB must be considered for safe removal. [ABSTRACT FROM AUTHOR]

This paper develops and benchmarks an immersed peridynamics method to simulate the deformation, damage, and failure of hyperelastic materials within a fluid-structure interaction framework. The immersed peridynamics method describes an incompressible structure immersed in a viscous incompressible fluid. It expresses the momentum equation and incompressibility constraint in Eulerian form, and it describes the structural motion and resultant forces in Lagrangian form. Coupling between Eulerian and Lagrangian variables is achieved by integral transforms with Dirac delta function kernels, as in standard immersed boundary methods. The major difference between our approach and conventional immersed boundary methods is that we use peridynamics, instead of classical continuum mechanics, to determine the structural forces. We focus on non-ordinary state-based peridynamic material descriptions that allow us to use a constitutive correspondence framework that can leverage well-characterized nonlinear constitutive models of soft materials. The convergence and accuracy of our approach are compared to both conventional and immersed finite element methods using widely used benchmark problems of nonlinear incompressible elasticity. We demonstrate that the immersed peridynamics method yields comparable accuracy with similar numbers of structural degrees of freedom for several choices of the size of the peridynamic horizon. We also demonstrate that the method can generate grid-converged simulations of fluid-driven material damage growth, crack formation and propagation, and rupture under large deformations. [ABSTRACT FROM AUTHOR]

In this paper, the shifted Jacobi spectral-Galerkin method is introduced to deal with fractional order initial value problems (FIVPs). In the proposed method, the exact solution of the FIVP is approximated by using shifted Jacobi polynomials on each subinterval of the total time. The main advantage of the proposed method is that the rate of convergence in L 2 -norm depends on the local smoothness of solution. This enables the proposed method to work for nonsmooth solutions. The second merit is that the flexibility between the length of sub-interval and the degree of polynomial significantly enhances the numerical accuracy. We derive the spectral-Galerkin approximation formula for the Volterra integral equation of the second kind which is equivalent to the FIVP. Error analysis in L 2 -norm for the case α = β = 0 in shifted Jacobi polynomials is provided and it justifies the spectral rate of convergence with respect to both the degree and the length of the subinterval when the source function is Lipschitz continuous in the second argument. Numerical illustrations for multi-order, linear, and nonlinear FIVPs are demonstrated to confirm the convergence rate. • We divide the time interval [0, T into a set of sub-intervals and approximate the solution by shifted Jacobi polynomials constructed on each sub-interval. • The method has the spectral rate of convergence in both the degree N of shifted Jacobi polynomial and the size of time sub-interval h. That is, the error ≈ h m i n N + 1 , s k N − s k , where s k represents a local smoothness of solution. • Computational cost is remarkably reduced because of solving a matrix system for each sub-interval. [ABSTRACT FROM AUTHOR]

• The Caputo fractional numerical differentiation is directly built from the original FDE so that the discrete formula for the solution has an explicit form. • The numerical formula for the Caputo fractional derivative is not involved by the derivative of y (t) so that a simple linear interpolate approximation can be easily applied. • For a fractional order ν ≈ 0, the stable perturbation technique is proposed compared with other methods. • Numerical performance can be boosted up by the technique of the decomposition of ν in case of that ν ≈ 1. This paper proposes new direct and acceleration numerical methods for solving Fractional order Differential Equations (FDEs). For the Caputo differential operator with fractional order 0 < ν < 1, we rewrite the FDE as an equivalent integral form circumventing the derivative of the solution by the integral by parts. We obtain a discrete formulation directly from the integral form using the Lagrange interpolate polynomials. We provide truncation errors depending on the fractional order ν for linear and quadratic interpolations, which are O (h 2 − ν) and O (h 3 − ν) respectively. In order to overcome a strong singular issue as ν ≈ 0 we propose the explicit predictor-corrector scheme with perturbation technique. In case of ν ≈ 1, the truncation errors are reduced by O (h) and O (h 2). In order to accelerate the convergence rate, we decompose ν = ν / 2 + ν / 2 , convert the FDE into the system of FDEs, and apply the predictor-corrector scheme. Numerical tests for linear, nonlinear, variable order and time-fractional sub-diffusion problems demonstrate that the proposed methods give a prominent performance. We also compare the numerical results with other high-order explicit and implicit schema. [ABSTRACT FROM AUTHOR]

The effect of knot clusters on the bending properties of Korean pine (Pinus koraiensis) cross-laminated timber (CLT) was analyzed to increase the utilization of low-quality lumber. The laminae used to manufacture the CLT were classified into five groups, four major layer groups, and one minor layer group, by mechanical grade and knot area ratio (KAR) of the lamina. Out-of-plane bending tests were conducted on CLT made from each layer group. The modulus of elasticity (MOE) of the manufactured CLT was closely correlated with the MOE of each individual major axis lamina. In the case of the modulus of rupture (MOR) of the CLT, the KAR of the laminae used in the major axis layer was more significantly affected than the MOE. The main finding is that the lower fifth percentile MOR value of the CLT specimens with large knots (KAR > 0.5) was higher than the acceptable reference value of E3 grade CLT (ANSI/APA PRG 320) made from a similar lamina grade. Therefore, the use of low-quality lumber to manufacture CLT can be expanded under the condition of limitation of the greater KAR. [ABSTRACT FROM AUTHOR]