390 research outputs found
Ergodic measures in minimal group actions with finite topological sequence entropy
Let be an infinite discrete countable group and be a minimal
-system. In this paper, we prove the supremum of topological sequence
entropy of is not less than
. If additionally is
abelian then there is a constant with such that where is
the maximal equicontinuous factor of , is the
factor map and is the Haar measure of .Comment: arXiv admin note: text overlap with arXiv:2002.08792 by other author
Precise Localization and Formation Control of Swarm Robots via Wireless Sensor Networks
Precise localization and formation control are one of the key technologies to achieve coordination and control of swarm robots, which is also currently a bottleneck for practical applications of swarm robotic systems. Aiming at overcoming the limited individual perception and the difficulty of achieving precise localization and formation, a localization approach combining dead reckoning (DR) with wireless sensor network- (WSN-) based methods is proposed in this paper. Two kinds of WSN localization technologies are adopted in this paper, that is, ZigBee-based RSSI (received signal strength indication) global localization and electronic tag floors for calibration of local positioning. First, the DR localization information is combined with the ZigBee-based RSSI position information using the Kalman filter method to achieve precise global localization and maintain the robot formation. Then the electronic tag floors provide the robots with their precise coordinates in some local areas and enable the robot swarm to calibrate its formation by reducing the accumulated position errors. Hence, the overall performance of localization and formation control of the swarm robotic system is improved. Both of the simulation results and the experimental results on a real schematic system are given to demonstrate the success of the proposed approach
Preliminary study of beta-blocker therapy on modulation of interleukin-33/ST2 signaling during ventricular remodeling after acute myocardial infarction
Background: This study aimed to evaluate the role of b-blocker therapy on modulating interleukin (IL)-33/ST2 (interleukin-1 receptor-like 1) signaling during ventricular remodeling related to heart failure (HF) after acute myocardial infarction (AMI).
Methods: Sprague-Dawley rats that survived surgery to induce AMI were randomly divided into the placebo group and the b-blocker treatment group. A sham group was used as a control. Left ventricular (LV) function variables, the myocardial infarct size, fibrosis and IL-33/ST2 protein expression was measured.
Results: Compared with the placebo group, b-blocker treatment significantly improved LV function and reduced infarct size (p < 0.05). There was higher protein expression of IL-33 (p < 0.05) and sST2 (p < 0.05), as well as higher expression of fibrosis (p < 0.05), compared to the sham group. Notably, the high expression of cardioprotective IL-33 was not affected by b-blocker treatment (p > 0.05), however, treatment with b-blocker enhanced IL-33/ST2 signaling, with lower expression of sST2 (p < 0.05) and significantly attenuated fibrosis (p < 0.05).
Conclusions: Our study suggested that b-blocker therapy might play a beneficial role in the modulation of IL-33/ST2 signaling during ventricular remodeling. These results may be helpful in identifying IL-33/ST2 systems as putative b-blocker targets at an early stage after AMI. (Cardiol J 2017; 24, 2: 188–194
Investigation of the topography-dependent current in conductive AFM and the calibration method
The topography and the electrical properties of materials are two crucial
characteristics in determining their functionalities. Conductive atomic force
microscopy (CAFM) is widely recognized for its ability to independently measure
the topology and conductivity of the sample surface. The increasing trend
towards miniaturization in electrical devices and sensors has led to an urgent
demand for enhancing the accuracy of CAFM characterization. However, the
sample's topography may affect the current measured by CAFM, leading to an
inaccurate estimation of the sample's conductivity. Herein, we investigated the
existence of topography-dependent current that originates from changes in
capacitance between the probe and sample in CAFM testing. A linear correlation
between the current and topography has been established using both experimental
and theoretical methods. A calibration method based on this linear correlation
has been proposed to eliminate the current error induced by the uneven surface
of both insulators and conductors. This work will yield substantial advantages
for research requiring high-precision CAFM testing.Comment: Corrected typo
A Coumarin–Hemicyanine Deep Red Dye with a Large Stokes Shift for the Fluorescence Detection and Naked-Eye Recognition of Cyanide
In this study, we synthesized a coumarin–hemicyanine-based deep red fluorescent dye that exhibits an intramolecular charge transfer (ICT). The probe had a large Stokes shift of 287 nm and a large molar absorption coefficient (ε = 7.5 × 105 L·mol−1·cm−1) and is best described as a deep red luminescent fluorescent probe with λem = 667 nm. The color of probe W changed significantly when it encountered cyanide ions (CN−). The absorption peak (585 nm) decreased gradually, and the absorption peak (428 nm) increased gradually, so that cyanide (CN−) could be identified by the naked eye. Moreover, an obvious fluorescence change was evident before and after the reaction under irradiation using 365 nm UV light. The maximum emission peak (667 nm) decreased gradually, whilst the emission peak (495 nm) increased gradually, which allowed for the proportional fluorescence detection of cyanide (CN−). Using fluorescence spectrometry, the fluorescent probe W could linearly detect CN− over the concentration range of 1–9 μM (R2 = 9913, RSD = 0.534) with a detection limit of 0.24 μM. Using UV-Vis spectrophotometry, the linear detection range for CN− was found to be 1–27 μM (R2 = 0.99583, RSD = 0.675) with a detection limit of 0.13 μM. The sensing mechanism was confirmed by 1H NMR spectroscopic titrations, 13C NMR spectroscopy, X-ray crystallographic analysis and HRMS. The recognition and detection of CN− by probe W was characterized by a rapid response, high selectivity, and high sensitivity. Therefore, this probe provides a convenient, effective and economical method for synthesizing and detecting cyanide efficiently and sensitively
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