Concise Fuzzy System Modeling Integrating Soft Subspace Clustering and Sparse Learning
IEEE TRANSACTIONS ON FUZZY SYSTEMS
Authors: Xu, Peng; Deng, Zhaohong; Cui, Chen; Zhang, Te; Choi, Kup-Sze; Suhang, Gu; Wang, Jun; Wang, Shitong
Abstract
The superior interpretability and uncertainty modeling ability of Takagi-Sugeno-Kang fuzzy system (TSK FS) make it possible to describe complex nonlinear systems intuitively and efficiently. However, classical TSK FS usually adopts the whole feature space of the data for model construction, which can result in lengthy rules for high-dimensional data and lead to degeneration in interpretability. Furthermore, for highly nonlinear modeling task, it is usually necessary to use a large number of rules which further weaken the clarity and interpretability of TSK FS. To address these issues, an enhanced soft subspace clustering (ESSC) and sparse learning (SL) based concise zero-order TSK FS construction method, called ESSC-SL-CTSK-FS, is proposed in this paper by integrating the techniques of ESSC and SL. In this method, ESSC is used to generate the antecedents and various sparse subspaces for different fuzzy rules, whereas SL is used to optimize the consequent parameters of the fuzzy rules based on which the number of fuzzy rules can be effectively reduced. Finally, the proposed ESSC-SL-CTSK-FS method is used to construct concise zero-order TSK FS that can explain the scenes in high-dimensional data modeling more clearly and easily. Experiments are conducted on various real-world datasets to confirm the advantages.
Fluid Shear Stress Suppresses Osteoclast Differentiation in RAW264.7 Cells through Extracellular Signal-Regulated Kinase 5 (ERK5) Signaling Pathway
MEDICAL SCIENCE MONITOR
Authors: Ma, Chongwen; Geng, Bin; Zhang, Xiaohui; Li, Rui; Yang, Xinxin; Xia, Yayi
Abstract
Background: Although extracellular signal-regulated kinase 5 (ERK5) is known to be critical for osteoclast differentiation, there are few studies on how fluid shear stress (FSS) regulates osteoclast differentiation through the ERK5 signaling pathway. We examined the expression of nuclear factor of activated T cells c1 (NFATc1) in RAW264.7 cells and its downstream factors, including cathepsin K (CTSK), tartrate-resistant acid phosphatase (TRAP), matrix metalloproteinases-9 (MMP-9) and their relationship with ERK5. Material/Methods: RAW264.7 cells were treated with RANKL, XMD8-92 (ERK5 inhibitor), and then loaded onto 12 dyn/cm(2) FSS for 4 days. Endpoints measured were osteoclast differentiation, bone resorption, and TRAP activity. Cell viability was detected by using the Cell Counting Kit-8 (CCK-8) assay. Western blot was used to analyze protein expression of phosphorylated-ERK5 (p-ERK5), NFATc1, CTSK, TRAP, and MMP-9. Results: FSS inhibited osteoclast differentiation and expression of NFATc1, CTSK, TRAP, and MMP-9; cell viability was not affected. ERK5 expression increased by FSS but not by RANKL, and it was blocked by XMD8-92. Furthermore, FSS suppressed osteoclast differentiation in RAW264.7 cells through ERK5 pathway. Conclusions: Our findings demonstrated that FSS inhibited osteoclast differentiation in RAW264.7 cells via the ERK5 path- way through reduced NFATc1 expression and its downstream factors MMP-9, CTSK, and TRAP.