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In this paper, we propose a penalized weighted quantile estimating equations (PWQEEs) method to obtain sparse, robust and efficient estimators for the quantile regression with longitudinal data. The PWQEE incorporates the within correlations in the longitudinal data by Gaussian copulas and can also down-weight the high leverage points in covariates to achieve double-robustness to both the non-normal distributed errors and the contaminated covariates. To overcome the obstacles of discontinuity of the PWQEE and nonconvex optimization, a local distribution smoothing method and the minimization–maximization algorithm are proposed. The asymptotic properties of the proposed method are also proved. Furthermore, finite sample performance of the PWQEE is illustrated by simulation studies and a real-data example. [ABSTRACT FROM AUTHOR]

Binary complex plasmas consist of microparticles of two different species and can form two-dimensional square lattices under certain conditions. The dispersion relations of the square lattice waves are derived for the longitudinal and transverse in-plane modes, assuming that the out-of-plane mode is suppressed by the strong vertical confinement. The results are compared with the spectra obtained in Langevin dynamics simulations. Furthermore, we investigate the dependence of the dispersion relation on the charge ratio and mass ratio of the two particle species. [ABSTRACT FROM AUTHOR]

Objective: The aim of our study was to investigate the relationship between nasal irrigation techniques (NIT) and the survival rate and the quality of life (QOL) in patients with nasal sinusitis (NS), Methods: We studied data from 1134 patients with nasopharyngeal carcinoma (NPC) who received radical radiotherapy, which were randomly divided into three groups (A, B and C). Group A used nasal irrigator; Group B used homemade nasal irrigation (Nl) connector combined with enemator; and Group C used nasal sprayer. The clinical effects, 5-year overall survival (OS) and progression-free survival (PFS) were observed. Furthermore, the QOL in patients with NS was evaluated using the Sino-Nasal Outcome Test 20. Results: The median follow-up time was 69 months. The 5-year OS and PFS were 80.5% and 73.2%, respectively, for all patients. There was no significant difference in OS, PFS, xerostomia and neck skin toxicity grade 3 and greater among groups. There was no difference among groups. The incidence of NS was the highest in group C. Conclusion: The symptoms of NS seriously affected the QOL period of 1 year. Group C showed no improvement during the follow-up period, which for A and B, by contrast, had after 1 year. Although the exact mechanism remains to be explored in NIT, our findings suggest that patients with NPC should nasal irrigate for 2 years after radiotherapy. Advances in knowledge: Our study shows that a nasal irrigator is necessary for patients with NPC for a high QOL in terms of NS. [ABSTRACT FROM AUTHOR]