An Improved Markov Model for IEEE 802.15.4 Slotted CSMA/CA Mechanism

IEEE 802.15.4 protocol is proposed to meet the low latency and energy consumption needs in low-rate wireless applications, however, few analytical models are tractable enough for comprehensive evaluation of the protocol. To evaluate the IEEE 802.15.4 slotted CSMA/CA channel access mechanism in this paper, we propose a practical and accurate discrete Markov chain model, which can dynamically represent different network loads. By computing the steady-state distribution probability of the Markov chain, we obtain an evaluation formula for throughput, energy consumption, and access latency. Then we further analyze the parameters that influence performance including packet arrival rate, initial backoff exponent and maximum backoff number. Finally, NS2 simulator has been used to evaluate the performance of the 802.15.4 CSMA/CA mechanism under different scenarios and to validate the accuracy of the proposed model.

A Fast Tongue Detection and Location Algorithm in Natural Environment

The collection and extraction of tongue images has always been an important part of intelligent tongue diagnosis.At present,the collection of tongue images generally needs to be completed in a sealed,stable light environment,which is not conducive to the promotion of extensive tongue image and intelligent tongue diagnosis.In response to the problem,a newalgorithm named GCYTD(GELU-CA-YOLO Tongue Detection)is proposed to quickly detect and locate the tongue in a natural environment,which can greatly reduce the restriction of the tongue image collection environment.The algorithm is based on the YOLO(You Only Look Once)V4-tiny network model to detect the tongue.Firstly,the GELU(Gaussian Error Liner Units)activation function is integrated into the model to improve the training speed and reduce the number of model parameters;then,the CA(Coordinate Attention)mechanism is integrated into the model to enhance the detection precision and improve the failure tolerance of the model.Compared with the other classical algorithms,Experimental results show thatGCYTD algorithm has a better performance on the tongue images of all types in terms of training speed,tongue detection speed and detection precision,etc.The lighter model can contribute on deploying the tongue detection model on small mobile terminals.

Mechanical force and cytoplasmic Ca^(2+) activate mechanosensitive BK channel in parallel

BK channels are widely expressed in both excitable and non-excitable cells and known to be involved in many physiological processes,such as vascular smooth tone regulation,neuronal firing and endocrine cell secretion[1].Recently, the BK channels have

Changchun Institute of Optics and Fine Mechanics and Physics of CAS

Changchun Institute of Optics, Fine Mechanics, and Physics (CIOMP) of CAS was established in Changchun, Jilin Province, on July 5, 1999 on the basis of consolidation of two former CAS institutes: Changchun Institute of Optics and Fine Mechanics, and Changchun Institute of Physics. The institute is an experimental unit of CAS Knowledge Innovation Program (KIP).

A novel TRPC6-dependent mechanism of TGF-β-induced migration and invasion of human hepatocellular carcinoma cells

Mechanisms on cancer cell migration and invasion have been major topics of cancer research and anti-cancer therapy development. Among the multiple cell signaling pathways involved in cell migration, those elicited by transforming growth factorβ（TGF-β） have attracted tremendous attention. The TGF-βpolypeptide cytokines include four isoforms：TGF-β1, TGF-β2, TGF-β3, and TGF-β4, which are secreted mainly from cells of white blood cell lineage, such as macrophages, T cells and platelets.

Effect of Extrusion Temperature on the Microstructure and Mechanical Properties of Mg–5Al–2Ca Alloy

In this work, the Mg–5Al–2Ca alloy was extruded at 573, 623 and 673 K, with a ratio of 16：1 and a constant speed of 3 mm/s. Results demonstrate that the Al2Ca particle is formed in Mg–5Al–2Ca alloy. The size, amount and distribution of Al2Ca particles are influenced evidently by extrusion temperature. Unlike previous reports, the intensity of basal texture increases with increasing extrusion temperature, and the reasons are analyzed and given. Even though the average grain size increases as the extrusion temperature increased from 573 to 623 K, the YS, UTS and elongation of asextruded Mg–5Al–2Ca alloy are almost kept the same at 573 and 623 K. The reason is speculated as the balance of grain size, Al2Ca phase and texture at the two temperatures. The work hardening rate depends on extrusion temperature, and the largest θ value of Mg–5Al–2Ca alloy is obtained when the extrusion was performed at 623 K.