Dear Editor, This letter presents a coverage optimization algorithm for underwater acoustic sensor networks (UASN) based on Dijkstra method. Due to the particularity of underwater environment, the ...multipath effect and channel are easily disturbed, resulting in more node energy consumption. Once the energy is exhausted, the network transmission stability and network connectivity will be affected. Coverage optimization is a key problem in UASN, which directly affects the network lifetime. Considering the complexity of underwater acoustic channel, the energy transfer model is improved in this paper. Dijkstra algorithm is used to transform global optimization into inter node optimization to achieve optimal coverage. The feasibility and complexity of the algorithm are analyzed. Simulation results show that compared with similar algorithms, this algorithm can achieve better network coverage, which prolongs the network lifetime and improves the network performance effectively.
Cyclic Nucleotide-Binding Domain (CNBD)-family channels display distinct voltage-sensing properties despite sharing sequence and structural similarity. For example, the human Ether-a-go-go Related ...Gene (hERG) channel and the Hyperpolarization-activated Cyclic Nucleotide-gated (HCN) channel share high amino acid sequence similarity and identical domain structures. hERG conducts outward current and is activated by positive membrane potentials (depolarization), whereas HCN conducts inward current and is activated by negative membrane potentials (hyperpolarization). The structural basis for the "opposite" voltage-sensing properties of hERG and HCN remains unknown.
We found the voltage-sensing domain (VSD) involves in modulating the gating polarity of hERG. We identified that a long-QT syndrome type 2-related mutation within the VSD, K525N, mediated an inwardly rectifying non-deactivating current, perturbing the channel closure, but sparing the open state and inactivated state. K525N rescued the current of a non-functional mutation in the pore helix region (F627Y) of hERG. K525N&F627Y switched hERG into a hyperpolarization-activated channel. The reactivated inward current induced by hyperpolarization mediated by K525N&F627Y can be inhibited by E-4031 and dofetilide quite well. Moreover, we report an extracellular interaction between the S1 helix and the S5-P region is crucial for modulating the gating polarity. The alanine substitution of several residues in this region (F431A, C566A, I607A, and Y611A) impaired the inward current of K525N&F627Y.
Our data provide evidence that a potential cooperation mechanism in the extracellular vestibule of the VSD and the PD would determine the gating polarity in hERG.
Myeloma cells retain B cell functions, considered to be potential antigen presenting cells, yet there is little information regarding promoting Th2 cell proliferation or the direct effects to myeloma ...on the Th2 cells stimulated by microbial antigens-loaded myeloma cells.
Mixed lymphocyte reaction was used colorimetric assays via CCK8-kit. Surface molecular expression was performed by flow cytometry, cells sorting using microbeads. The concentrations of cytokines in serum were assessed using an ELISA kit. Clonogenic assay were performed in a methylcellulose culture system. Statistical analysis was assessed using the Student's t-test or one-way analysis of variance for multiple comparisons test.
The expression of HLA-DR, CD80 and CD40 on RPMI8266 cell membrane surface was upregulated by interaction with interferon-γ and/or Bacillus Calmette-Guerin Vaccine (BCGV). RPMI8266 cells were able to induce the mixed lymphocyte reaction in a dose-dependent fashion. The Th2 ratio induced by RPMI8266 treated by BCGV and interferon-γ (treated-RPMI8266) cells was only slightly greater than by untreated-tumor cells, but the serum IL-4 level secreted by Th2 cells was markedly higher in treated-RPMI8266 cells group. Th2 cells stimulated by treated-myeloma cells could directly promote treated-myeloma cell clonogenicity in a dose-dependent manner. Anti-HLADR IgG2b completely blocked increased of IL-4 secretion by Th2 cells stimulated by treated-myeloma cells, while also blocked enhancing the clonogenicity of treated tumor cells stimulated by MM-Th2 cells.
These results indicate that a novel mechanism of myeloma pathogenesis in myeloma cells could act as an APC to present microbial Ags to Th2 cells, promoting Th2 cell proliferation, consequently facilitating tumor development by close interaction between Th2 myeloma cells. Taken together, the microbial Ag presenting course of MM-Th2-MM interactions-restricted by MHC class-II-may result in tumor development such that all factors involved in the system could have a potential for myeloma therapeutic intervention.
•A distributed data integrity verification method without third-party auditor is proposed. Based on the constructed hashTable, each hospital server can audit the data in a distributed manner.•A ...blockchain-based auditing scheme is designed for cloud-edge healthcare system, which includes the consensus protocol Proof of Auditing Frequency (PoAF) and related block structures.•The proposed scheme is evaluated against two start-of-the-art schemes in a simulated cloud-edge healthcare system and comprehensively evaluated.
Cloud-edge healthcare system provides storage and computing functions at the hospital servers, bringing low latency for doctors and patients. However, hospital servers cannot be trusted and have limited computing resources. Data integrity verification for the cloud-edge healthcare system is an urgent concern. To this end, we proposed a data integrity auditing scheme based on blockchain. First, a distributed data integrity verification method without a third-party auditor is designed. The data are divided into smaller parts and hashed into a hash table. The verification tag is constructed according to the column of the hash table and secret string generated by a pseudo-random function. Then, a detailed blockchain-based data integrity auditing scheme is proposed, including Proof of Auditing Frequency and block structure. Besides, a security analysis for the common attacks is given. Finally, the proposed scheme is evaluated against two start-of-the-art schemes in a simulated cloud-edge healthcare system. The results demonstrate that the proposed scheme can verify data integrity without losing efficiency.
In this paper, the trade-off between utility and energy consumption in orthogonal frequency division multiplexing (OFDM)-based cognitive radio (CR) network is investigated. Energy efficiency problem ...is very important in the field of CR network, where the utility is maximized and the energy consumption is minimized in such a CR network. Since the trade-off between them has been paying more attentions in literature, this study summarizes the power allocation as an optimization problem that maximizes the energy efficiency via a new energy efficiency metric defined by this paper. The formulated problem is a large-scale nonconvex problem, which is very difficult to solve. In this paper, we present an improved particle swarm optimization (PSO) algorithm to solve the difficult large-scale optimization problem directly. Given the weak convergence of the original PSO around local optima, an improved version that combines the chaos theory is proposed in this study, where chaos theory can help PSO search for solutions around the personal and global bests. In addition, for the purpose of accelerating the convergence process when facing with such a large-scale optimization, the original problem is decomposed into a number of small ones by employing the coevolutionary methodology, and then divide-and-conquer strategy is used to avoid producing infeasible solutions. Simulations demonstrate that the proposed coevolution chaotic PSO needs a smaller number of iterations and can achieve more energy efficiency than the other algorithms.
With the rapid development of wireless sensor networks, reducing energy consumption is becoming one of the important factors to extend node lifetime, and it is necessary to adjust the launching power ...of each node because of the limited energy available to the sensor nodes in the networks. This paper proposes a power and rate control model based on the network utility maximization (NUM) framework, where a weighting factor is used to reflect the influence degree of the sending power and transmission rate to the utility function. In real networks, nodes interfere with each other in the procedure of transmitting signal, which may lead to signal transmission failure and may negatively have impacts on networks throughput. Using dual decomposition techniques, the NUM problem is decomposed into two distributed subproblems, and then the conjugate gradient method is applied to solve the optimization problem with the calculation of the Hessian matrix and its inverse in order to guarantee fast convergence of the algorithm. The convergence proof is also provided in this paper. Numerical examples show that the proposed solution achieves significant throughput compared with exiting approaches.
This paper proposes a disturbance observer-based anti-disturbance control strategy for a class of stochastic systems subject to two kinds of disturbances. One represents the stochastic disturbance ...with partially-known information. The other is an independent Wiener process. The stochastic disturbance observer can be constructed separately from the controller design to estimate the first kind of disturbance. Based on stochastic disturbance observer, a novel anti-disturbance control scheme is proposed to improve the ability of anti-disturbance for stochastic systems. A simulation example is given to demonstrate the effectiveness of the proposed method.
In this paper, we study the distributed output tracking problem for nonlinear multi-agent systems (MASs) perturbed by second-order moment processes. This is in contrast with most of the existing ...results where only white noise model is considered. For the case where the graph topology is directed and the leader is the neighbor of only a small portion of followers, new distributed tracking control laws are designed via the distributed backstepping method. By using the stochastic analysis tools, it is shown that the output tracking errors between the followers and the leader can be tuned arbitrarily small while all the states of the closed-loop system remain bounded in probability. Finally, the effectiveness of the tracking controller is demonstrated by a simulation example.
Independent interactive medical applications cooperate closely with user systems through independent information and data exchange, which realizes digital and intelligent communication for health ...monitoring system. Due to extensive connectivity and application services, heavy data traffic and limited energy consumption reduce the quality of application services. In this paper, a mathematical model for efficient energy harvesting resource allocation based on cognitive radio sensor network (CRSN) infrastructure is constructed to address energy limitation issues in health monitoring system applications. Because of the highly dynamic nature of available network resources, energy efficiency and communication reliability can be improved. Since the proposed optimization problem is a complex and NP hard problem, coevolutionary theory is adopted, and then a stochastic optimization algorithm based on polynomial approximation and quantum particle swarm optimization is proposed. Simulation results show that the proposed CQPSO algorithm has better performance in terms of re-transmission probability, system throughput, and energy consumption compared to other similar algorithms. Efficient resource allocation improves the performance of the health monitoring system, more effectively and real-time monitoring of human physiological and motion information, providing testers with high-precision quantitative information, and achieving early monitoring and intervention of common diseases.
•The additional antenna provides more space freedom and improves throughput.•The modeling problem is to maximize the network utility under uncertainty.•Bernstein approximation technique is used to control the approximation error.•Coevolution theory is adopted to deal with the large-scale character of problems.
This paper investigates the utility maximization problem for the downlink of the multi-interface multichannel wireless mesh network with orthogonal frequency division multiple access. A cross-layer ...joint power and multiple access control algorithm are proposed. Rosen projection matrix is combined with Solodov projection techniques to build a three-memory gradient Rosen projection method, which is applied to solve this optimization problem. The convergence analysis is given and simulations show that the proposed solution achieves significant throughput compared with existing approaches.
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