Nasopharyngeal carcinoma (NPC), a malignant tumor at the top and side of the nasopharyngeal cavity, highly occurs in the southern region of China. Cancer cell metastasis is one of the leading causes of death in NPC patients. Osteopontin (OPN), is a phosphorylated extracellular matrix protein with a variety of functions, was found to be overexpressed in many cancers. However, the expression and role of OPN in patients with NPC in Guangxi, China are unclear. Here, we observed that NPC patients had upregulated OPN at mRNA protein and levels. Immunochemistry (IHC) analysis of OPN expression in 68 NPC clinical specimens indicated that high expression of OPN had positive correlation with NPC lymph node metastasis (P = 0.012), distant metastasis (P = 0.001) and TNM staging (P = 0.018). Moreover, compared with relatively low OPN, NPC patients with higher expression of OPN showed a poorer overall survival rate (P = 0.001, log rank test). Multivariate analysis showed that OPN expression in NPC was an independent prognostic marker. The proliferation, apoptosis and migration ability of CEN-2Z cancer cells in NPC were determined by MTT, flow cytometry and wound-healing assays, respectively. Upregulation of OPN in CEN-2Z cancer cells promoted cancer cell proliferation and migration, and suppressed apoptosis. In sum, our result suggests OPN could be used as a valuable oncoprotein and show that overexpression of OPN in NPC may serve as a potential prognostic marker.

In this paper, a two-neuron system with inertia and delay is proposed firstly. a PD controller is then applied to the system for the purpose of improving its dynamical performance. Through the mathematical transformation, we extend the system to a four-dimensional one with only time delays. With the help of the associated characteristic equation of the mathematical model, suffcient conditions for ensuring the system stability are proposed. Furthermore, with the time delay as the bifurcation parameter, relevant requirements for the generation of Hopf bifurcation are derived. Then a series of numerical simulatiosns are carried out to justify the theoretical analysis and it is found that the application of PD control scheme helps to advance the bifurcation point dramatically through a slight adjustment of the controller parameters.

The optimal control of dynamics is a popular topic for small-world networks. In this paper, we address the problem of improving the behavior of Hopf bifurcations in an integer-order model of small-world networks. In this study, the time delay is used as the bifurcation parameter. We add a fractional-order proportional-derivative (PD) scheme to an integer-order Newman-Watts (N-W) small-world model to better control the Hopf bifurcation of the model. The most important contribution of this paper involves obtaining the stability of the system and the variation of the conditions of the Hopf bifurcation after a fractional PD controller is added to the integer-order small-world model. The results demonstrate that the designed PD controller can be used to restrain or promote the occurrence of Hopf bifurcations by setting appropriate parameters. We also describe several simulations to verify our research results.

This paper proposed an original fractional-order proportional-derivative (PD) feedback controller which is designed to control the Hopf bifurcation caused by the congestion control system. The proposed P D 1 n controller has the different order with the original congestion system. The proposed fractional-order PD controller has the different order with the controlled system and the communication delay is selected as the bifurcation parameter. Then the conditions of the stability and Hopf bifurcation are obtained by analyzing its characteristic equation and the stability domain can be extended under the adjustment of appropriate control gain parameters and the order. Therefore, the congestion system becomes controllable and the desirable behaviors can be realized. Finally, numerical simulations are carried out to testify the validity of the theoretical analysis in the designed fractional-order PD controller.

No abstract