631 research outputs found

    The boundedness of commutators of sublinear operators on Herz Triebel-Lizorkin spaces with variable exponent

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    In this paper, the authors first discuss the characterization of Herz Triebel-Lizorkin spaces with variable exponent via two families of operators. By this characterization, the authors prove that the Lipschitz commutators of sublinear operators is bounded from Herz spaces with variable exponent to Herz Triebel-Lizorkin spaces with variable exponent. As an application, the corresponding boundedness estimates for the commutators of maximal operator, Riesz potential operator and Calder\'on-Zygmund operator are established.Comment: commutator; sublinear operator; Lipschitz spaces; Herz Triebel-Lizorkin spaces; variable exponen

    EEG-based fatigue driving detection using correlation dimension

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    Driver fatigue is an important cause of traffic accidents and the detection of fatigue driving has been a hot issue in automobile active safety during the past decades. The purpose of this study is to develop a novel method to detect fatigue driving based on electroencephalogram (EEG). The volunteer is asked to perform simulated driving tasks under different mental state while EEG signals are acquired simultaneously from six electrodes at central, parietal and occipital lobe, including C3, C4, P3, P4, O1 and O2. Due to the non-linearity of human brain responses, correlation dimension is estimated with G-P algorithm to quantify the collected EEGs. Statistical analysis reveals significant decreases from awake to fatigue state of the correlation dimension for all the channels across 5 subjects (awake state: 3.87±0.13; fatigue state: 2.76±0.34; p< 0.05, paired t-test), which indicates that the correlation dimension is a promising parameter in detecting fatigue driving with EEGs

    Learning the Uncertainty Sets for Control Dynamics via Set Membership: A Non-Asymptotic Analysis

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    Set-membership estimation is commonly used in adaptive/learning-based control algorithms that require robustness over the model uncertainty sets, e.g., online robustly stabilizing control and robust adaptive model predictive control. Despite having broad applications, non-asymptotic estimation error bounds in the stochastic setting are limited. This paper provides such a non-asymptotic bound on the diameter of the uncertainty sets generated by set membership estimation on linear dynamical systems under bounded, i.i.d. disturbances. Further, this result is applied to robust adaptive model predictive control with uncertainty sets updated by set membership. We numerically demonstrate the performance of the robust adaptive controller, which rapidly approaches the performance of the offline optimal model predictive controller, in comparison with the control design based on least square estimation's confidence regions

    Epithelial-Mesenchymal Transition in tumor microenvironment

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    The epithelial to mesenchymal transition (EMT) plays crucial roles in the formation of the body plan and also in the tumor invasion process. In addition, EMT also causes disruption of cell-cell adherence, loss of apico-basal polarity, matrix remodeling, increased motility and invasiveness in promoting tumor metastasis. The tumor microenvironment plays an important role in facilitating cancer metastasis and may induce the occurrence of EMT in tumor cells. A large number of inflammatory cells infiltrating the tumor site, as well as hypoxia existing in a large area of tumor, in addition many stem cells present in tumor microenvironment, such as cancer stem cells (CSCs), mesenchymal stem cells (MSCs), all of these may be the inducers of EMT in tumor cells. The signaling pathways involved in EMT are various, including TGF-β, NF-κB, Wnt, Notch, and others. In this review, we discuss the current knowledge about the role of the tumor microenvironment in EMT and the related signaling pathways as well as the interaction between them

    Prognostic value of growth differentiation factor-15 in Chinese patients with heart failure: A prospective observational study

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      Background: Growth differentiation factor-15 (GDF-15), a biomarker associated with remodeling, oxidative stress and inflammation, has been used to stratify heart failure (HF) patients. However, its prognostic value in Chinese HF patients is still unknown. Methods: GDF-15 levels were examined on admission in 272 consecutive HF patients in Beijing Hospital (a Chinese tertiary medical center) by a commercial enzyme-linked immunosorbent assay. We recorded the incidence of all-cause mortality and/or readmission for HF during a median follow-up period of 558 days. Patients were stratified according to the tertiles of GDF-15. Results: Fifty-three (19.5%) patients died and 103 (37.9%) patients had major adverse cardiac events (MACE) which included the composite outcome of all-cause mortality or readmission for HF at the end of follow-up. Kaplan-Meier survival curves showed that the third tertile of GDF-15 was associated with increased rate of all-cause mortality (compared with the first and second tertiles, log rank p = 0.001 and 0.001, respectively) or MACE (compared with the first and second tertiles, log rank p = 0.002 and p &lt; 0.001, respectively). In addition, multivariate Cox regression model showed that the highest tertile of GDF-15 was independently associated with increased risk of all-cause death (hazard ratio = 5.95, 95% confidence interval 1.88–18.78, p = 0.002) compared with the lowest tertile after adjustment for related clinical variables such as age, renal function or N-terminal pro-B-type natriuretic peptide.  Conclusions: Plasma GDF-15 is an independent predictor of all-cause mortality in Chinese patients with HF. It may potentially be used to stratify and prognosticate HF patients

    The role of immunosuppression of mesenchymal stem cells in tissue repair and tumor growth

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    Mesenchymal stem cells (MSCs) have acquired great interests for their potential use in the clinical therapy of many diseases because of their functions including multiple lineage differentiation, low immunogenicity and immunosuppression. Many studies suggest that MSCs are strongly immunosuppressive in vitro and in vivo. MSCs exert a profound inhibitory effect on the proliferation of T cells, B cells, dendritic cells and natural killer cells. In addition, several soluble factors have been reported to involved in the immunosuppressive effects by MSCs such as TGF-β, HGF, PGE2, IDO and iNOS. These results suggest that MSCs can be used in the therapy of immune disorder diseases, prevention of organ transplantation rejection and tissue injury. In recent study, we demonstrated that MSCs in tumor inflammatory microenvironment might be elicited of immunosuppressive function. Thus, the application of MSCs in cancer therapy might have negative effect by helping tumor cells escaping from the immune surveillance

    Soil organic pollution and ecological risk assessment in brownfield soil from Northwest China: an integrated analysis of man-land interrelations

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    In general, chemical plants are accompanied by a variety of secondary production in the production process, which may have different degrees of impact on the environment. At the same time, in order to ensure the environmental safety of new urban construction land, it is necessary to conduct pollution investigation and further environmental risk assessment on potentially polluting abandoned chemical plants. This paper takes a chemical plant producing food grade fumaric acid in Northwest China as an example to investigate the pollution of organic matter in the soil in accordance with relevant standards, then analyzes the vertical pollution degree of key pollution areas. The calculation results of single factor pollution index and Nemerow pollution index show that there are 17 kinds of organic pollutants that exceed the screening value in land of Class I. Among them, benzene, 1,2,3-trichloropropane and 1,1,2,2-tetrachloroethane are most serious, and the highest exceeded the standard by 11,311 times. Moreover, the distillation zone and the reactor zone have reached the level of V pollution, and the maximum pollution depth can reach more than 6 m. The results of HERA software analysis showed that there were 18 and 10 kinds of organic pollutants with carcinogenic risk values exceeding 10−6 in the reactor and distillation area, respectively, and 25 and 11 kinds of organic pollutants with hazard quotients exceeding 1, respectively. According to relevant regulations, the contaminated areas with unacceptable regional risks must be properly repaired
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