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This paper is concerned with the parameter estimation in linear regression model. To overcome the multicollinearity problem, a new class of estimator, namely principal component two-parameter (PCTP) estimator is proposed. The superiority of the new estimator over the principal component regression (PCR) estimator, the r − k class estimator, the r − d class estimator and the two-parameter estimator proposed by Yang and Chang (Commun Stat Theory Methods 39:923-934 2010) are discussed with respect to the mean squared error matrix (MSEM) criterion. Furthermore, we give a numerical example and a simulation study to illustrate some of the theoretical results.

PurposeThere is no effective treatment for liver fibrosis, which is a common phase during the progression of many chronic liver diseases to cirrhosis. Previous studies found that Semen Brassicae therapy can effectively improve the clinical symptoms of patients with asthma, allergic rhinitis, and chronic lung diseases; however, its effects on liver fibrosis in rats and its possible mechanisms of action remain unclear.MethodsRats were injected intraperitoneally with 4% thioacetamide aqueous solution (5 mL·kg−1) at a dose of 200 mg·kg−1 twice a week for 8 consecutive weeks to establish the liver fibrosis model and were then treated with different concentrations of Semen Brassicae extract. After Semen Brassicae treatment, the morphology of the liver tissue was analyzed using hematoxylin and eosin and Masson’s trichrome staining, and liver index and liver fibrosis grade were calculated. Thereafter, the levels of collagen-I, collagen-III, α-SMA, transforming growth factor (TGF)-β1, p-Smad 2/3, Smad 2/3, Smad4, NF-κB-p65, p-NF-κB-p65, IL-1β, IL-6, AKT, and p-AKT were determined using Western blotting.ResultsCompared with the untreated model group, the Semen Brassicae-treated group showed significantly decreased liver function indices; expression levels of collagen-I, collagen-III, and α-SMA; and hepatic fibrosis. Further studies also showed that the expression of TGF-β1, Smad4, p-Smad 2/3/Smad 2/3, p-NF-κB-p65/NF-κB-p65, IL-1β, IL-6, and p-AKT/AKT significantly decreased after the treatment.ConclusionThese results indicate that Semen Brassicae exhibits an anti-hepatic fibrosis effect, and the underlying mechanism of action may be related to the regulation of TGF-β1/Smad, NF-κB, and AKT signaling pathways and the reduction of extracellular matrix deposition.

Under the new development pattern, promoting urban green transformation efficiently addresses resource and environmental restrictions and is the foundation of high-quality development. However, the development of green transformation in Chinese cities faces constraints in three dimensions, production, life, and ecology, and it is not clear whether the digital economy, as a key driver of green development, can empower urban green transformation. Therefore, this paper measures the level of urban green transformation from the three dimensions of production, life, and ecological space and empirically tests the impact of the digital economy on urban green transformation from 2011 to 2020 by using panel data from 41 cities in the Yangtze River Delta urban agglomeration. The results indicate: (1) The development of the green transformation level in the Yangtze River Delta urban agglomeration demonstrates a constant upward trend, but the absolute difference fluctuates and declines; (2) the development of the digital economy has a positive impact on urban green transformation, as well as changes in urban production, living, and ecological space; (3) the digital economy helps the green transformation of cities by supporting the growth of an advanced and rationalized industrial structure. Nevertheless, the indirect influence of an advanced and rational industrial structure on urban green transformation is quite different.

This paper is concerned with the parameter estimation in logistic regression model. To overcome the multicollinearity problem, Schaefer et al. (1984) and Urgan and Tez (2008), respectively, proposed the logistic ridge regression estimator and logistic Liu estimator for the logistic regression model. In this article, the almost unbiased Ridge and Liu estimator are proposed by applying the almost unbiased method. Necessary and sufficient conditions for the superiority of the new estimators over the logistic ridge regression estimator and logistic Liu estimator in the mean squared error sense are derived.