Control spiral wave dynamics using feedback signals from line detectors

We numerically study trajectories of spiral-wave-cores in excitable systems modulated proportionally to the integral of the activity on the straight line, several or dozens of equi-spaced measuring points on the straight line, the double-line and the contour-line. We show the single-line feedback results in the drift of core center along a straight line being parallel to the detector. An interesting finding is that the drift location in $y$ is a piecewise linear-increasing function of both the feedback line location and time delay. Similar trajectory occurs when replacing the feedback line with several or dozens of equi-spaced measuring points on the straight line. This allows to move the spiral core to the desired location along a chosen direction by measuring several or dozens of points. Under the double-line feedback, the shape of the tip trajectory representing the competition between the first and second feedback lines is determined by the distance of two lines. Various drift attractors in spiral wave controlled by square-shaped contour-line feedback are also investigated. A brief explanation is presented.Comment: 6 pages and 7 figures; Accepted for publication in EPL; Figs.5 and 6 are in JPG forma

Expression of DNMT1 and DNMT3a Are Regulated by GLI1 in Human Pancreatic Cancer

BACKGROUND AND AIMS: GLI1, as an indispensable transcriptional factor of Hedgehog signaling pathway, plays an important role in the development of pancreatic cancer (PC). DNA methyltransferases (DNMTs) mediate the methylation of quantity of tumor-related genes. Our study aimed to explore the relationship between GLI1 and DNMTs. METHODS: Expressions of GLI1 and DNMTs were detected in tumor and adjacent normal tissues of PC patients by immunohistochemistry (IHC). PANC-1 cells were treated by cyclopamine and GLI1-siRNA, while BxPC-3 cells were transfected with overexpression-GLI1 lentiviral vector. Then GLI1 and DNMTs expression were analyzed by qRT-PCR and western blot (WB). Then we took chromatin immunoprecipitation (ChIP) to demonstrate GLI1 bind to DNMT1. Finally, nested MSP was taken to valuate the methylation levels of APC and hMLH1, when GLI1 expression altered. RESULTS: IHC result suggested the expressions of GLI1, DNMT1 and DNMT3a in PC tissues were all higher than those in adjacent normal tissues (p<0.05). After GLI1 expression repressed by cyclopamine in mRNA and protein level (down-regulation 88.1±2.2%, 86.4±2.2%, respectively), DNMT1 and DNMT3a mRNA and protein level decreased by 91.6%±2.2% and 83.8±4.8%, 87.4±2.7% and 84.4±1.3%, respectively. When further knocked down the expression of GLI1 by siRNA (mRNA decreased by 88.6±2.1%, protein decreased by 63.5±4.5%), DNMT1 and DNMT3a mRNA decreased by 80.9±2.3% and 78.6±3.8% and protein decreased by 64.8±2.8% and 67.5±5.6%, respectively. Over-expression of GLI1 by GLI1 gene transfection (mRNA increased by 655.5±85.9%, and protein increased by 272.3±14.4%.), DNMT1 and DNMT3a mRNA and protein increased by 293.0±14.8% and 578.3±58.5%, 143.5±17.4% and 214.0±18.9%, respectively. ChIP assays showed GLI1 protein bound to DNMT1 but not to DNMT3a. Results of nested MSP demonstrated GLI1 expression affected the DNA methylation level of APC but not hMLH1 in PC. CONCLUSION: DNMT1 and DNMT3a are regulated by GLI1 in PC, and DNMT1 is its direct target gene

Control of spiral waves and spatiotemporal chaos by periodic perturbation near the boundary

In this paper, the relation between the excited period and the perturbation one is firstly studied, and several segments of linear relation can be found. Their appearance is mainly due to the existence of vulnerable periods and absolute refractory ones. Further, a method for controlling spiral waves and spatiotemporal chaos in excitable media is proposed. In the method, a target wave train is generated by periodic perturbation in a small rectangle region near the left boundary, and competes with spiral waves or spatiotemporal chaos. The availability and efficiency of the control depend on the comparison of excited periods between spiral waves or spatiotemporal chaos and target wave trains, the selection of perturbation period is tied to the relation between the excited period and the perturbation one. These results are interesting to understand many real cases, such as heart diseases and their therapy. We find spiral-wave tip can flee away from the boundary, but the elimination of the tip is very difficult. The effect of noise is also considered

Fabrication of Ultralow Ice-Adhesion Slippery Liquid Infused Porous Surfaces on Aluminum Alloy (7075-T651)

Slippery liquid infused porous surfaces (SLIPS) have been considered to be potential and effective method for anti-icing. Much work needed to be done for the application in field. In this study, SLIPS were successfully fabricated on 7075-T651 aluminum alloy by anodizing in phosphoric acid solution with three different voltage parameters and coating lubricant. Then the most suitable anodization parameters of samples were selected through the anti-icing performance tests. The best as-prepared surface exhibited ultralow ice-adhesion strength, which reduced from 261 to 6 kPa. Meanwhile, the freezing time of water-drop on aluminum alloy surfaces have been dramatically delayed at &minus;5 and &minus;10 &deg;C (humidity of 75% &plusmn; 5%), respectively. Moreover, the durability of the SLIPS have also been investigated. Cycles of icing/deicing, mechanical damage, thermal and UV exposure were used to investigate the durability of SLIPS, and SLIPS could still show low ice-adhesion strength

Customized proximal point algorithms for linearly constrained convex minimization and saddle-point problems: A unified approach

This paper focuses on some customized applications of the proximal point algorithm (PPA) to two classes of problems: the convex minimization problem with linear constraints and a generic or separable objective function, and a saddle-point problem. We treat these two classes of problems uniformly by a mixed variational inequality, and show how the application of PPA with customized metric proximal parameters can yield favorable algorithms which are able to make use of the models' structures effectively. Our customized PPA revisit turns out to unify some algorithms including some existing ones in the literature and some new ones to be proposed. From the PPA perspective, we establish the global convergence and a worst-case O(1/t) convergence rate for this series of algorithms in a unified way. © 2013 Springer Science+Business Media New York.Link_to_subscribed_fulltex