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This paper aims to study stable portfolios with mean-variance-CVaR criteria for high-dimensional data. Combining different estimators of covariance matrix, computational methods of CVaR, and regularization methods, we construct five progressive optimization problems with short selling allowed. The impacts of different methods on out-of-sample performance of portfolios are compared. Results show that the optimization model with well-conditioned and sparse covariance estimator, quantile regression computational method for CVaR, and reweighted L1 norm performs best, which serves for stabilizing the out-of-sample performance of the solution and also encourages a sparse portfolio.

In this paper, random matrix theory is employed to perform information selection and denoising, and mean-realized variance-CVaR multi-objective portfolio models before (after) denoising are constructed for high-frequency data. The empirical study is conducted based on high-frequency data from stocks in the SSE 180 Index. Compared with the existing literatures, the main contribution of this paper is the introduction of both realized covariance matrix and random matrix theory in multi-objective portfolio problem. The result shows that the use of the realized covariance matrix can reduce the loss of market information, and random matrix theory could help improve the quality of information contained in correlation matrix among assets. Under the denoised mean-realized variance-CVaR criterion, the new portfolio selection has better out-of-sample performance.

microRNAs (miRNAs) are a class of small non-coding RNAs that can post-transcriptionally regulate gene expression and play critical roles in many important biological processes. The role of miRNAs in prostate cancer (PCa) development and pathogenesis remains largely unknown. In the present study, we showed that miR-200b was downregulated in clinical prostatic tumors when compared to normal prostate tissue and in advanced PCa cell lines when compared to normal epithelial prostatic cells. Enforced miR-200b expression suppressed PCa cell proliferation and migration and enhanced chemosensitivity to docetaxel by targeting B-cell-specific Moloney murine leukemia virus insertion site 1 (Bmi-1). Bmi-1 was detected at higher levels in PCa, and knockdown of Bmi-1 showed similar effects as miR-200b overexpression in PCa cells. Moreover, we confirmed that these effects were correlated with increased levels of E-cadherin and P16 and a reduction in vimentin expression and expression of stem cell markers (CD44 and OCT4). These findings suggest that miR-200b plays vital roles as a tumor-suppressor by targeting Bmi-1 and may be a promising therapeutic target for PCa treatment.

Background The purpose of the study was to investigate parents’ perceptions of antibiotic use for their children, interactions between parents and physicians regarding treatment with antibiotics, and factors associated with parents self-medicating children with antibiotics. Methods A cross-sectional study was conducted in vaccination clinics in two rural Chinese counties. Primary caregivers (the child’s parents in 97% of cases) visiting these clinics for the vaccination of their young children were given a 55-item structured questionnaire to collect information on the parents’ knowledge and attitudes regarding when, why, and how to use antibiotics and on their practices of purchasing antibiotics and medicating children. Results Of the 854 participating primary caregivers, 79% thought antibiotics could cure viral infections, and half believed that antibiotics could shorten the duration of upper respiratory tract infection. Parents reported a median of two hospital visits for their children during the previous 6 months, equal to the median number of antibiotic prescriptions received from physicians. Sixty-two percent of the parents had self-medicated their children with antibiotics. Living in rural villages (Adj OR = 1.643, 95% CI: 1.108–2.436), raising more than one child (Adj OR = 2.174, 95% CI: 1.485–3.183), increasing age of child (Adj OR = 1.146, 95% CI: 1.037–1.266), purchasing antibiotics without a prescription (Adj OR = 6.264, 95% CI: 4.144–9.469), storing antibiotics at home (Adj OR = 2.792, 95% CI: 1.961–3.975) and good adherence to physicians’ advice (Adj OR = 0.639, 95% CI: 0.451–0.906) were independently associated with self-medicating behavior. Conclusions Low levels of knowledge on the use of antibiotics and a high prevalence of self-medicating children with antibiotics were observed among parents in rural China. Interventions for the rational use of antibiotics in children should focus on strengthening mass health education, improving effective communication between physicians and patients, and enforcing supervision of the sale of antibiotics in retail pharmacies.