Receiver-Initiated Handshaking MAC Based on Traffic Estimation for Underwater Sensor Networks

In underwater sensor networks (UWSNs), the unique characteristics of acoustic channels have posed great challenges for the design of medium access control (MAC) protocols. The long propagation delay problem has been widely explored in recent literature. However,the long preamble problem with acoustic modems revealed in real experiments brings new challenges to underwater MAC design. The overhead of control messages in handshaking-based protocols becomes significant due to the long preamble in underwater acoustic modems. To address this problem, we advocate the receiver-initiated handshaking method with parallel reservation to improve the handshaking efficiency. Despite some existing works along this direction, the data polling problem is still an open issue. Without knowing the status of senders, the receiver faces two challenges for efficient data polling: when to poll data from the sender and how much data to request. In this paper, we propose a traffic estimation-basedreceiver-initiated MAC(TERI-MAC)to solve this problem with an adaptive approach. Data polling in TERI-MAC depends on an online approximation of traffic distribution. It estimates the energy efficiency and network latency and starts the data request only when the preferred performance can be achieved. TERI-MAC can achieve a stable energy efficiency with arbitrary network traffic patterns. For traffic estimation, we employ a resampling technique to keep a small computation and memory overhead. The performance of TERI-MAC in terms of energy efficiency, channel utilization, and communication latency is verified in simulations. Our results show that, compared with existing receiver-initiated-based underwater MAC protocols, TERI-MAC can achieve higher energy efficiency at the price of a delay penalty. This confirms the strength of TERI-MAC for delay-tolerant applications

Receiver-Initiated Handshaking MAC Based On Traffic Estimation for Underwater Sensor Networks

In underwater sensor networks (UWSNs), the unique characteristics of acoustic channels have posed great challenges for the design of medium access control (MAC) protocols. The long propagation delay problem has been widely explored in recent literature. However, the long preamble problem with acoustic modems revealed in real experiments brings new challenges to underwater MAC design. The overhead of control messages in handshaking-based protocols becomes significant due to the long preamble in underwater acoustic modems. To address this problem, we advocate the receiver-initiated handshaking method with parallel reservation to improve the handshaking efficiency. Despite some existing works along this direction, the data polling problem is still an open issue. Without knowing the status of senders, the receiver faces two challenges for efficient data polling: when to poll data from the sender and how much data to request. In this paper, we propose a traffic estimation-based receiver-initiated MAC (TERI-MAC) to solve this problem with an adaptive approach. Data polling in TERI-MAC depends on an online approximation of traffic distribution. It estimates the energy efficiency and network latency and starts the data request only when the preferred performance can be achieved. TERI-MAC can achieve a stable energy efficiency with arbitrary network traffic patterns. For traffic estimation, we employ a resampling technique to keep a small computation and memory overhead. The performance of TERI-MAC in terms of energy efficiency, channel utilization, and communication latency is verified in simulations. Our results show that, compared with existing receiver-initiated-based underwater MAC protocols, TERI-MAC can achieve higher energy efficiency at the price of a delay penalty. This confirms the strength of TERI-MAC for delay-tolerant applications

Reliable and Efficient Data Transfer for Underwater Acoustic Networks

As an emerging research area, Underwater Acoustic Networks (UANs) have attracted tremendous interests in last several years. Reliable and efficient data transfer is of critical importance for UANs since it provides essential services for various tasks. Due to the unique features of UANs including the long propagation delay, low bandwidth and high error probability, reliable and efficient data transfer has been facing great challenges. In this dissertation work, we tackle this problem from three different perspectives. Hybrid ARQ (HARQ), which combines Forward Error Correction (FEC) Coding and Automatic Repeat reQuest (ARQ) has been proved to be an effective way to counter packet loss caused by error prone UAN channels. Along this path, we propose three HARQ based schemes. We focus on string topology unicast UANs, which have been widely adopted for underwater applications. What these three schemes have in common is that they all employ a combination of FEC coding and ARQ. However, they choose different FEC coding schemes based on the underlying UAN platforms and targeted application scenarios. Also different multi-hop coordination schemes are adopted to handle collisions. Underwater Hybrid ARQ (UW-HARQ) is a simple end-to-end approach targeted for UANs with limited computation capability and power capacity. Random Binary Linear Coding is employed by UW-HARQ due to its low complexity and an optimal coding ratio estimation scheme is proposed. For powerful UAN platforms with more computation capacity and less energy constraint, we design a Coding based multi-hop Coordinated Reliable Data Transfer (CCRDT) protocol, which is tailored for multi-hop homogeneous string topology UANs. GF(256) Random Linear Coding is employed to enhance reliability and efficiency over one hop. A multi-hop coordination scheme is proposed to eliminate collisions and improve throughput. CCRDT has been implemented on real UAN nodes and extensive lab tests have been conducted to show its advantages over existing approaches. To work with heterogeneous UANs where channel quality on different links sometimes varies significantly, Fountain code based Adaptive multi-hop Reliable data transfer (FOCAR) is proposed. A multi-hop optimization approach is incorporated into FOCAR to achieve minimum end-to-end delay over multiple hops. The three HARQ based approaches are targeted for string topology unicast UANs. To address the reliable and efficient broadcast problem for UANs, we propose a Two-phase Broadcast (TBS) scheme. TBS does not rely on topology or neighbor information and thus is more adaptive to the dynamic changes in UANs. TBS includes two phases: the Fast Spreading phase and the Data Recovery phase. The Fast Spreading phase combines opportunistic overhearing and network coding to improve broadcast efficiency. The Data Recovery phase aims to guarantee reliability and reduce interference probability. CCRDT and FOCAR utilize multi-hop coordination to eliminate collisions in string topology UANs. By contrast, we propose a Selective ARQ and Slotted Handshake based Access (SASHA), for arbitrary topology UANs, which allows the occurrence of collisions but is able to recover from them. SASHA embraces the most commonly employed techniques in coordination based UAN MAC design. We implemented SASHA on real UAN nodes and conducted a sea test to evaluate its performance. We investigated the hop-by-hop and end-to-end behavior of SASHA. From the experimental data, practical issues have been discovered and corresponding design guidelines are suggested

PDK4 rescues high-glucose-induced senescent fibroblasts and promotes diabetic wound healing through enhancing glycolysis and regulating YAP and JNK pathway

Abstract During the process of wound healing, fibroblasts migrate to the wound site and perform essential functions in promoting cell proliferation, as well as synthesizing and secreting the extracellular matrix (ECM). However, in diabetic wounds, senescent fibroblasts exhibit impaired proliferative capacity and fail to synthesize essential ECM components. Pyruvate dehydrogenase kinase 4 (PDK4), a key enzyme regulating energy metabolism, has been implicated in modulating cellular senescence and fibroblast function. However, its specific role in diabetic wounds remains poorly understood. In this study, we conducted a series of in vivo and in vitro experiments using STZ-induced diabetic mice and human dermal fibroblasts. We evaluated cellular senescence markers, including SA-β-gal, P53, P16, P21, and PAI-1, as well as senescence-associated secretory phenotype (SASP) factors. Finally, we observed that PDK4 increased in normal wound healing, but its expression was insufficient in diabetic wounds. Significantly, the overexpression of PDK4 demonstrated the potential to accelerate diabetic wound healing and improve the senescence phenotype both in vivo and in vitro. Furthermore, our study elucidated the underlying mechanism by which PDK4 improved the senescent phenotype through the enhancement of glycolysis and regulation of YAP and JNK pathway. The effect was dependent on metabolic reprogramming and subsequent reduction of reactive oxygen species (ROS), which was mediated by PDK4. Overall, our findings highlight the potential of PDK4 as a promising therapeutic target for addressing diabetic wounds

The design of index system of irregularities considering the whole process of electricity market transaction

In the early stage of competitive trading of electric power market, the imperfection of market mechanism hinders the normal development of market competition, which leads to the defects of competition system and a large number of market transaction irregularities. The study of the irregularities of the market subject in the new background can provide a new strategy for the future power market. The study of the irregularities of the market subject in the new background can provide a new strategy for the future power market. In view of this, this paper first combed the analysis process of irregularities of whole process of electricity market trading. Then, the paper divides them from three time scales, namely, pre transaction, transaction and post transaction, and analyzes the three irregularities and reasons of the basic information accuracy and matching degree before transaction, the vicious bidding strategy in transaction, and the completion situation after the transaction. Finally, an index system of irregularities is proposed for the whole process of electricity market transaction, which will provide a useful reference for future effective supervision of market transactions, reduce the occurrence of irregularities and ensure the smooth development of market transactions

The design of index system of irregularities considering the whole process of electricity market transaction

In the early stage of competitive trading of electric power market, the imperfection of market mechanism hinders the normal development of market competition, which leads to the defects of competition system and a large number of market transaction irregularities. The study of the irregularities of the market subject in the new background can provide a new strategy for the future power market. The study of the irregularities of the market subject in the new background can provide a new strategy for the future power market. In view of this, this paper first combed the analysis process of irregularities of whole process of electricity market trading. Then, the paper divides them from three time scales, namely, pre transaction, transaction and post transaction, and analyzes the three irregularities and reasons of the basic information accuracy and matching degree before transaction, the vicious bidding strategy in transaction, and the completion situation after the transaction. Finally, an index system of irregularities is proposed for the whole process of electricity market transaction, which will provide a useful reference for future effective supervision of market transactions, reduce the occurrence of irregularities and ensure the smooth development of market transactions

Receiver-Initiated Handshaking MAC Based on Traffic Estimation for Underwater Sensor Networks ^‡

In underwater sensor networks (UWSNs), the unique characteristics of acoustic channels have posed great challenges for the design of medium access control (MAC) protocols. The long propagation delay problem has been widely explored in recent literature. However, the long preamble problem with acoustic modems revealed in real experiments brings new challenges to underwater MAC design. The overhead of control messages in handshaking-based protocols becomes significant due to the long preamble in underwater acoustic modems. To address this problem, we advocate the receiver-initiated handshaking method with parallel reservation to improve the handshaking efficiency. Despite some existing works along this direction, the data polling problem is still an open issue. Without knowing the status of senders, the receiver faces two challenges for efficient data polling: when to poll data from the sender and how much data to request. In this paper, we propose a traffic estimation-based receiver-initiated MAC (TERI-MAC) to solve this problem with an adaptive approach. Data polling in TERI-MAC depends on an online approximation of traffic distribution. It estimates the energy efficiency and network latency and starts the data request only when the preferred performance can be achieved. TERI-MAC can achieve a stable energy efficiency with arbitrary network traffic patterns. For traffic estimation, we employ a resampling technique to keep a small computation and memory overhead. The performance of TERI-MAC in terms of energy efficiency, channel utilization, and communication latency is verified in simulations. Our results show that, compared with existing receiver-initiated-based underwater MAC protocols, TERI-MAC can achieve higher energy efficiency at the price of a delay penalty. This confirms the strength of TERI-MAC for delay-tolerant applications

Root Metabolism and Effects of Root Exudates on the Growth of <i>Ralstonia solanacearum</i> and <i>Fusarium moniliforme</i> Were Significantly Different between the Two Genotypes of Peanuts

Wild peanut species Arachis correntina (A. correntina) had a higher continuous cropping tolerance than peanut cultivars, closely correlating with the regulatory effects of its root exudates on soil microorganisms. To reveal the resistance mechanism of A. correntina to pathogens, we adopted transcriptomic and metabolomics approaches to analyze differentially expressed genes (DEGs) and differentially expressed metabolites (DEMs) between A. correntina and peanut cultivar Guihua85 (GH85) under hydroponic conditions. Interaction experiments of peanut root exudates with Ralstonia solanacearum (R. solanacearum) and Fusarium moniliforme (F. moniliforme) were carried out in this study. The result of transcriptome and metabolomics association analysis showed that there were fewer up-regulated DEGs and DEMs in A. correntina compared with GH85, which were closely associated with the metabolism of amino acids and phenolic acids. Root exudates of GH85 had stronger effects on promoting the growth of R. solanacearum and F. moniliforme than those of A. correntina under 1 and 5 percent volume (1% and 5%) of root exudates treatments. Thirty percent volume (30%) of A. correntina and GH85 root exudates significantly inhibited the growth of two pathogens. The exogenous amino acids and phenolic acids influenced R. solanacearum and F. moniliforme showing concentration effects from growth promotion to inhibition as with the root exudates. In conclusion, the greater resilience of A. correntina) to changes in metabolic pathways for amino acids and phenolic acids might aid in the repression of pathogenic bacteria and fungi