A Sparse Ridge Estimation for the Sparse Logistic Regression Model

Xiaotian Sun,최호식,권성훈 한국자료분석학회 2014 Journal of the Korean Data Analysis Society Vol.16 No.4

In this paper, we study a new penalized maximum likelihood estimator, the sparse ridge, for the sparse logistic regression model. Here, the sparsity of the logistic model implies that the model includes some irrelevant predictive variables. Hence, by deleting the irrelevant predictive variables from the model, we want to identify a correct sub-model, enhancing both prediction accuracy and model interpretability. For the problem, the sparse ridge gives a simultaneous process of selecting relevant predictive variables and estimating included parameters. First, the sparse ridge achieves a sparsity as usual penalized maximum likelihood estimators such as the least absolute selection and shrinkage operator and smoothly clipped absolute deviation penalized estimators. Hence we can use the sparse ridge for variable selection for the sparse logistic regression model. Further, the sparse ridge shares a common shrinkage effect in parameter estimation with the ridge. Hence the sparse ridge is expected to perform well under the multi-collinearity, especially. Numerical studies via simulated and real data analysis show that the sparse ridge can be a nice alternative to the well-known penalized maximum likelihood estimators.

Nonlinear Anti-swing Control of Underactuated Tower Crane Based on Improved Energy Function

Huaitao Shi,Jianqi Huang,Xiaotian Bai,Xiang Huang,Jie Sun 제어·로봇·시스템학회 2021 International Journal of Control, Automation, and Vol.19 No.12

The control system of tower crane exhibits strong nonlinearity in the process of control execution, which is prone to the problems of inaccurate positioning control of the payload and difficult anti-swing control. Aiming at the problems, this paper proposes a control law based on improved energy coupling analysis for suppressing the payload swing in the tower cranes. A three-dimensional dynamic model of tower crane system with considering friction is established, and an improved energy coupling signal is designed. The coupling relationship of trolley movement and payload swing, jib rotation and payload swing are considered, then a nonlinear anti-swing controller is established in order to reduce the swing. The closed-loop stability of the system with the controller is verified by the Lyapunov method and LaSalle invariance principle, simulations and experimental analyses are performed to verify the controller performance. The control performance of the controller is compared with other classic and typical current control methods, and the proposed controller outperformed other controllers. The anti-swing controller proposed in this paper has accurate positioning, and can achieve precise control when the payload is transported, reaching the set target position in a little time and eliminating residual swing angle. Meanwhile the proposed controller has a good control robustness, which can restore stability in around a very short time when the rope length and payload mass of the system’s inherent property are changed and external interference is added. In addition, when different target position parameters are uncertain, the proposed control law has good robust performance.

Experimental Investigation on the Properties of Sustainable Pervious Concrete with Different Aggregate Gradation

Junyu Zhang,Haoran Sun,Xiaotian Shui,Wenxuan Chen 한국콘크리트학회 2024 International Journal of Concrete Structures and M Vol.18 No.2

Pervious concrete (PC) as a green infrastructure material has been increasingly used due to its positive environmental impacts, such as controlling storm water runoff, removing water pollutants and reducing heat island effect. The aggregate gradation is a critical factor influencing the physical properties of PC. Therefore, this paper represents an attempt to determine the effects of aggregate gradation on the various physical properties of PC, and then to explore relationships between them. To this end, three aggregate gradations 4.75–9.5 mm, 9.5–19 mm and 19–31.5 mm were recombined with various proportions (20–80%) to obtain five different gradations named as A, B, C, D and E. PC mixtures were prepared with these five aggregate gradations. Then, physical and mechanical properties of PC including porosity, permeability, compressive strength and water stability were investigated, according to the available specification. The results suggested that it was feasible to use waste concrete for permeable pavement, because all the specimens provided required specification requirements. Different linear relationships were also found between the maximum aggregate size and porosity, permeability coefficient, compressive strength and its loss rate. That is, porosity and permeability increased with the proportion of larger size aggregate increased, however, compressive strength reduced. Thus the compressive strength had an inverse correlation with the porosity and water permeability. Among five different aggregate gradations, group C (20% of 4.75–9.5 mm aggregate, 50% of 9.5–19 mm aggregate and 30% of 19–31.5 mm aggregate) can be seen as the optimum gradation and is suitable for base layer materials of permeable pavements.

Molecular and Cellular Microbiology / Biomedical Sciences : Alteration of the Metabolome Profile in Endothelial Cells by Overexpression of miR-143/145

( Wenshuo Wang ),( Ye Yang ),( Yiqing Wang ),( Liewen Pang ),( Jiechun Huang ),( Hongyue Tao ),( Xiaotian Sun ),( Chen Liu ) 한국미생물 · 생명공학회 2016 Journal of microbiology and biotechnology Vol.26 No.3

Communication between endothelial cells (ECs) and smooth muscle cells (SMCs) via miR-143/145 clusters is vital to vascular stability. Previous research demonstrates that miR-143/145 released from ECs can regulate SMC proliferation and migration. In addition, a recent study has found that SMCs also have the capability of manipulating EC function via miR-143/145. In the present study, we artificially increased the expression of miR-143/145 in ECs, to mimic a similar change caused by miR-143/145 released by SMCs, and applied untargeted metabolomics analysis, aimed at investigating the consequential effect of miR-143/145 overexpression. Our results showed that miR-143/145 overexpression alters the levels of metabolites involved in energy production, DNA methylation, and oxidative stress. These changed metabolites indicate that metabolic pathways, such as the SAM cycle and TCA cycle, exhibit significant differences from the norm with miR-143/145 overexpression.

Trastuzumab combined with irinotecan in patients with HER2-positive metastatic colorectal cancer: A phase II single-arm study and exploratory biomarker analysis

Ting Xu,Xicheng Wang,Ying Xin,Zhenghang Wang,Jifang Gong,Xiaotian Zhang,Yanyan Li,Congcong Ji,Yu Sun,Feilong Zhao,Depei Huang,Yuezong Bai,Jian Li,Lin Shen 대한암학회 2023 Cancer Research and Treatment Vol.55 No.2

Purpose The human epidermal growth factor receptor 2 (HER2) is an established therapeutic target for various kinds of solid tumors. HER2 amplification occurs in approximately 1% to 6% of colorectal cancer. In this study, we aimed to assess the efficacy and safety of trastuzumab in combination with chemotherapy in HER2-positive metastatic colorectal cancer (mCRC). Materials and Methods An open-label, phase II trial (Clinicaltrials.gov: NCT03185988) was designed to evaluate the antitumor activity of trastuzumab and chemotherapy in HER2-positive digestive cancers excluding gastric cancer in 2017. Patients from this trial with HER2-positive, KRAS/BRAF wild-type, unresectable mCRC were analyzed in this manuscript. Eligible patients were treated with trastuzumab (8 mg/kg loading dose and then 6 mg/kg every 3 weeks) and irinotecan (120 mg/m2 days 1 and 8 every 3 weeks). The primary endpoint was the objective response rate. Results Twenty-one HER2-positive mCRC patients were enrolled in this study. Seven patients (33.3%) achieved an objective res-ponse, and 11 patients (52.4%) had stable disease as their best response. The median progression-free survival (PFS) was 4.3 months (95% confidence interval, 2.7 to 5.9). Four of the 21 patients (19.0%) had grade 3 adverse events, including leukopenia, neutropenia, urinary tract infection, and diarrhea. No treatment-related death was reported. Exploratory analyses revealed that high tumor tissue HER2 copy number was associated with better therapeutic response and PFS. Alterations in the mitogen-activated protein kinase pathway, HER2 gene, phosphoinositide 3-kinase/AKT pathway, and cell cycle control genes were potential drivers of trastuzumab resistance in mCRC. Conclusion Trastuzumab combined with chemotherapy is a potentially effective and well-tolerated therapeutic regimen in mCRC with a high HER2 copy number.