This paper presents the comparison results of a study to identify an appropriate semi-active control algorithm for a MR suspension system from a variety of semi-active control algorithms for use with MR dampers. Five representative control algorithms are considered including the skyhook controller, the hybrid controller, the LQG controller, the sliding mode controller and the fuzzy logic controller. To compare the control performances of the five control algorithms, a quarter car model with a MR damper is adopted as the baseline model for our analysis. After deriving the governing motion equations of the proposed dynamic model, five controllers are developed. Then each control policy is applied to the baseline model equipped with a MR damper. The performances of each control algorithm under various road conditions are compared along with the equivalent passive model in both time and frequency domains through the numerical simulation. Subsequently, a road test is performed to validate the actual control performance. The results show that the performance of a MR suspension X. Dong ( ) system is highly dependent on the choice of algorithm employed, and the sliding mode control strategy exhibits an excellent integrated performance.
Human chromosome 8p23 is known as a region that is associated with loss of heterozygosity (LOH), which is frequently deleted in hepatocellular carcinoma (HCC) tissues. We report here the characterization of a gene for a liver-related putative tumor suppressor (LPTS) localized at 8p23, that was isolated by allelic-loss mapping and positional candidate cloning. The expression of the gene for LPTS was ubiquitous in normal human tissues, albeit at relatively low levels, whereas levels appeared to be significantly reduced, or sometimes undetectable in HCC cells and neoplastic tissues. Thus, it appeared that LPTS might be involved in the control of cell proliferation. Indeed, we observed the significant suppression of growth and growth arrest of SMMC-7721 HCC cells after introduction of the gene for LPTS. We also used antisense oligodeoxynucleotides (AS-ODNs) to suppress the expression of LPTS in normal liver cells L02. Several ASODNs specific for LPTS mRNA significantly enhanced cell growth, whereas control oligodeoxynucleotides (ODNs) did not. Our results suggest that LPTS might be a growthinhibitory protein in human hepatocytes. (HEPATOLOGY 2000;32:721-727.)
Small cell lung cancer (SCLC) has a high degree of plasticity and is characterized by a remarkable response to chemotherapy followed by the development of resistance. Here, we use a mouse SCLC model to show that intratumoral heterogeneity of SCLC is progressively established during SCLC tumorigenesis. YAP/TAZ and Notch are required for the generation of non-neuroendocrine (Non-NE) SCLC tumor cells, but not for the initiation of SCLC. YAP signals through Notch-dependent and Notch-independent pathways to promote the fate conversion of SCLC from NE to Non-NE tumor cells by inducing Rest expression. In addition, YAP activation enhances the chemoresistance in NE SCLC tumor cells, while the inactivation of YAP in Non-NE SCLC tumor cells switches cell death induced by chemotherapy drugs from apoptosis to pyroptosis. Our study demonstrates that YAP plays critical roles in the establishment of intratumoral heterogeneity and highlights the potential of targeting YAP for chemoresistant SCLC.
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