Search

Programmable smart contracts facilitate the application of blockchain to many areas of industry, e.g., supply chains, energy, and healthcare. The off-chain execution model for blockchain smart contracts is a promising approach to achieve scalability for industrial applications, which executes each smart contract in one of the small-scale consensus groups. However, previous work based on such a model cannot efficiently handle cross-group contract transactions that involve multiple cross-group invocations between smart contracts because of the heavyweight state synchronization and repeated executions. In this article, we propose interactive consensus-based off-chain execution (ICOE), a lightweight group-consensus-based off-chain execution model, for cross-group contract transactions without the need of state synchronization and duplicate executions and also prove its correctness. The key novelty of our ICOE is to let the invoked smart contract only executed in its residing group and only return the execution result to the invoking smart contract while leveraging the two-phase commit protocol to guarantee consistent commits across multiple groups within the same invoking smart contract transaction. We implement ICOE and the extensive experimental results show that our ICOE achieves a 14× improvement of throughput on average compared with the state-of-the-art model.

Concurrent execution of smart contracts is a promising approach to boost their performance in current blockchain systems. However, prior work on concurrent execution only considered each smart contract transaction as a single atomic unit for the concurrent scheduling, which is not suitable for the increasingly complex smart contracts with high contention in practice. In this article, we present SC-Chef, a new concurrency control system to turboboost smart contract concurrent execution for high contention workloads via the transaction decomposition. The key novelty of our SC-Chef is to decompose the original transaction into multiple subtransactions that can be executed independently, while still respecting the original logic dependency. We implement and evaluate our SC-Chef in the private Ethereum platform. Our extensive experiments show that our SC-Chef outperforms the classic optimistic concurrency control and two-phase lock by 60% and 70% on average in the case of high contention, respectively.

In this article, we present a system PA SAL to explore the feasibility to enable visible light localization without adopting three practices as follows: 1) the LED as the transmitter modulates the signal; 2) the object of interest as the receiver carries light-sensing devices; and 3) place a large number of photodiodes in indoor environments. Specifically, we exploit the photoelectric characteristics of LED and spectral selectivity of RGB-LED to design an RGB-LED unit as both the transmitter and receiver. Inside the RGB-LED unit, we use the novel rake RGB-LED series layout perspective to increase the direct current response and sensing range of the detector, instead of simply combining a large number of monochromatic LEDs. Furthermore, we propose a joint received intensity positioning algorithm, which effectively recognizes the direction of the object, to achieve localization. In the end, we prototype PA SAL with off-the-shelf devices, and extensive experiments demonstrate that our PA SAL system could accurately sense the object and achieve localization. We believe our PA SAL system offers a new perspective to achieve both sensing and localization, and could serve as a promising complement to existing solutions.

The effect of nonacylated and acylated anthocyanins on urinary metabolites in diabetic rats was investigated. Nonacylated anthocyanins extract from bilberries (NAAB) or acylated anthocyanins extract from purple potatoes (AAPP) was given to Zucker diabetic fatty (ZDF) rats for 8 weeks at daily doses of 25 and 50 mg/kg body weight. 1H NMR metabolomics was applied to study alterations in urinary metabolites from three time points (weeks 1, 4, and 8). Both types of anthocyanins modulated the metabolites associated with the tricarboxylic acid cycle, gut microbiota metabolism, and renal function at weeks 1 and 4, such as 2-oxoglutarate, fumarate, alanine, trigonelline, and hippurate. In addition, only a high dose of AAPP decreased monosaccharides, formate, lactate, and glucose levels at week 4, suggesting improvement in energy production in mitochondria, glucose homeostasis, and oxidative stress. This study suggested different impacts of AAPP and NAAB on the metabolic profile of urine in diabetes.

Docosahexaenoic acid [22:6(n-3), DHA] plays an important role in human physiology including gut health. This research aimed to investigate the impact of positional distribution of DHA in dietary triacylglycerols (TAG) on gut metabolomic profile and microbiota. In the 4-week feeding trial, the Sprague-Dawley rats were fed on an n-3 deficient feed supplemented with TAG containing DHA at the sn-1, 2, or 3 position and palmitic acid at the remaining positions. Three groups receiving standard n-3 adequate feed, n-3 deficient feed, or n-3 deficient feed supplemented with tripalmitin were included as controls. The gut metabolome was studied using LC–MS-based non-targeted metabolomics, and microbiota profiles were investigated by 16S rRNA sequencing. Compared to the n-3 adequate diet, four-week feeding on the n-3 deficient diet affected the fecal pyrimidine metabolism, steroid biosynthesis, and arginine and proline metabolism. Feeding with DHA-containing TAGs, especially TAG with DHA at sn-3 position, increased the level of N5-Carboxy aminoimidazole ribonucleotide related to purine biosynthesis and dimethylbenzimidazole involved in vitamin B2 biosynthesis. N-3 deficient diet lowered the abundance of the genus Alistipesand the species Bacteroides massiliensisin the gut microbiota. Compared to the n-3 deficient groups, feeding with DHA-containing TAGs decreased the abundance of species Prevotellasp. CAG: 1031, and feeding with sn-2 DHA resulted in an increase in the abundance of Bacteroides fragilisand a decrease in the abundance of Faecalibacteriumsp. CAP 74. This is the first study showing that dietary DHA from different positions of TAG may affect gut metabolites and microbiota differently.

Anthocyanins have been reported to possess antidiabetic effects. Recent studies indicate acylated anthocyanins have better stability and antioxidative activity compared to their nonacylated counterparts. This study compared the effects of nonacylated and acylated anthocyanins on hepatic gene expression and metabolic profile in diabetic rats, using full-length transcriptomics and 1H NMR metabolomics. Zucker diabetic fatty (ZDF) rats were fed with nonacylated anthocyanin extract from bilberries (NAAB) or acylated anthocyanin extract from purple potatoes (AAPP) at daily doses of 25 and 50 mg/kg body weight for 8 weeks. Both anthocyanin extracts restored the levels of multiple metabolites (glucose, lactate, alanine, and pyruvate) and expression of genes (G6pac, Pck1, Pklr, and Gck) involved in glycolysis and gluconeogenesis. AAPP decreased the hepatic glutamine level. NAAB regulated the expression of Mgat4a, Gstm6, and Lpl, whereas AAPP modified the expression of Mgat4a, Jun, Fos, and Egr1. This study indicated different effects of AAPP and NAAB on the hepatic transcriptomic and metabolic profiles of diabetic rats.

Blue light has been previously reported to play a salient role in the treatment of seasonal affective disorder. The present study aimed to investigate whether blue light had antidepressant effect on light-deprivation-induced depression model, and the underlying visual neural mechanism. Blue light mitigated depression-like behaviors induced by light deprivation as measured by elevated sucrose preference and reduced immobility time. Blue light enhanced melanopsin expression and light responses in the retina. We also found the upregulation of serotonin and brain derived neurotrophic factor expression in the c-fos-positive areas of rats treated with blue light compared with those maintained in darkness. The species gap between nocturnal albino (Sprague-Dawley rat) and diurnal pigmented animals (human) might have influenced extrapolating data to humans. Blue light has antidepressant effect on light-deprived Sprague-Dawley rats, which might be related to activating the serotonergic system and neurotrophic activity via the retinoraphe and retinoamygdala pathways. Blue light is the effective component of light therapy for treatment of depression.

This study compared the effects of the nonacylated and acylated anthocyanin-rich extracts on plasma metabolic profiles of Zucker diabetic fatty rats. The rats were fed with the nonacylated anthocyanin extract from bilberries (NAAB) or the acylated anthocyanin extract from purple potatoes (AAPP) at daily doses of 25 and 50 mg/kg body weight for 8 weeks. 1H NMR metabolomics was used to study the changes in plasma metabolites. A reduced fasting plasma glucose level was seen in all anthocyanin-fed groups, especially in the groups fed with NAAB. Both NAAB and AAPP decreased the levels of branched-chain amino acids and improved lipid profiles. AAPP increased the glutamine/glutamate ratio and decreased the levels of glycerol and metabolites involved in glycolysis, suggesting improved insulin sensitivity, gluconeogenesis, and glycolysis. AAPP decreased the hepatic TBC1D1and G6PCmessenger RNA level, suggesting regulation of gluconeogenesis and lipogenesis. This study indicated that AAPP and NAAB affected the plasma metabolic profile of diabetic rats differently.

1,4-Naphthoquinone-coated BC (1,4 NQ-BC) is an important component of PM2.5and a representative secondary particle. However, there is no research on the crosstalk mechanism between necroptosis and macrophage extracellular traps (METs) after 1,4 NQ-BC exposure. In this study, we treated RAW264.7 cells with 50, 100, and 200 mg/L 1,4 NQ-BC for 24 h, with 10 μM necrostatin-1 for 24 h, and with 2.5 μM phorbol 12-myristate 13-acetate (PMA) for 3 h. Our experiment revealed that under normal physiological conditions, when macrophages receive external stimuli (such as pathogens; in this experiment, PMA), they will form METs and capture and kill pathogens, thus exerting innate immune function. However, exposure to 1,4 NQ-BC can cause necroptosis in macrophages, accompanied by increased levels of reactive oxygen species (ROS) and cytosolic calcium ions, as well as the expression disorder of inflammatory factors and chemokines, prevent the formation of METs, lead to loss of the function of capturing and killing pathogens, and weaken the innate immune function. Notably, inhibition of necroptosis restored the formation of METs, indicating that necroptosis inhibited the formation of METs. Our study was the first to explore the crosstalk mechanism between necroptosis and METs. This experiment will enrich the mechanism of macrophage injury caused by 1,4 NQ-BC exposure.

Currently, the elastic interconnection has realized the high-rate data transmission among data centers (DCs). Thus, the elastic data center network (EDCN) emerged. In EDCNs, it is essential to achieve the virtual network (VN) embedding, which includes two main components: VM (virtual machine) mapping and VL (virtual link) mapping. In VM mapping, we allocate appropriate servers to hold VMs. While for VL mapping, an optimal substrate path is determined for each virtual lightpath. For the VN embedding in EDCNs, the power efficiency is a significant concern, and some solutions were proposed through sleeping light-duty servers. However, the increasing communication traffic between VMs leads to a serious energy dissipation problem, since it also consumes a great amount of energy on switches even utilizing the energy-efficient optical transmission technique. In this paper, considering load balancing and power-efficient VN embedding, we formulate the problem and design a novel heuristic for EDCNs, with the objective to achieve the power savings of servers and switches. In our solution, VMs are mapped into a single DC or multiple DCs with the short distance between each other, and the servers in the same cluster or adjacent clusters are preferred to hold VMs. Such that, a large amount of servers and switches will become vacant and can go into sleep mode. Simulation results demonstrate that our method performs well in terms of power savings and load balancing. Compared with benchmarks, the improvement ratio of power efficiency is 5%–13%. 本文将考虑了负载均衡的虚拟网络嵌入能效问题抽象成数学模型, 并提出了一种综合考虑服务器和交换机能耗的绿色虚拟网络嵌入算法, 力求将虚拟机映射到彼此物理距离更近的服务器中, 并根据链路频谱信息和交换机当前能耗设置链路代价, 以指导虚拟链路进行节能性的映射。通过大量仿真, 本文证明了所提出算法在节能和负载均衡方面的优势。

The processed surface contour shape is extracted with the finite element simulation software. The difference value of contour shape change is used as the parameters of balancing surface roughness to construct finite element model of supersonic vibration milling in cutting stability domain. The surface roughness trial scheme is designed in the orthogonal test design method to analyze the surface roughness test result in the response surface methodology. The surface roughness prediction model is established and optimized. Finally, the surface roughness finite element simulation prediction model is verified by experiments. The research results show that, compared with the experiment results, the error range of the finite element simulation model is 27.5%–30.9%, and the error range of the empirical model obtained by the response surface method is between 4.4% and 12.3%. So, the model in this paper is accurate and will provide the theoretical basis for the optimization study of the auxiliary milling process of supersonic vibration.

If a false rumor propagates via Twitter, while the truth propagates between friends in Facebook, which one will prevail? This question captures the essence of the problem we address here. We study the intertwined propagation of two competing "memes" (or viruses, rumors, products etc.) in a composite network. A key novelty is the use of a composite network, which in its simplest model is defined as a single set of nodes with two distinct types of edges interconnecting them. Each meme spreads across the composite network in accordance to an SIS-like propagation model (a flu-like infection-recovery). To study the epidemic behavior of our system, we formulate it as a non-linear dynamic system (NLDS). We develop a metric for each meme that is based on the eigenvalue of an appropriately constructed matrix and argue that this metric plays a key role in determining the "winning" meme. First, we prove that our metric determines the tipping point at which both memes become extinct eventually. Second, we conjecture that the meme with the strongest metric will most likely prevail over the other, and we show evidence of that via simulations in both real and synthetic composite networks. Our work is among the first to study the interplay between two competing memes in composite networks.

In this paper, we investigate survivability in wavelength division multiplexing (WDM) mesh networks and propose a new algorithm called improved shared-path protection (ISPP) to completely tolerate the double-link failures. Compared with previous algorithms for protecting double-link failures, i.e., shared-path protection (SPP) and shared-link protection (SLP), the advantage of ISPP is to allow primary paths and backup paths to share the mixed wavelength-links based on the proposed new rules in which some primary wavelength-links can be changed to mixed wavelength-links, which can be shared by primary paths and backup paths. In addition, some mixed wavelength-links also can be shared by different backup paths for saving resources. Simulation results show that ISPP algorithm performs better in resource utilization ratio and blocking probability than conventional SPP and SLP algorithms.

In recent years, the demands of high traffic transmission motivate the rapid development of wireless access techniques, and it becomes promising to design the fifth generation (5G) wireless networks. Essential requirements for 5G involve higher traffic volume, indoor or hotspot traffic, and spectrum, energy, and cost efficiency. So compared with the previous four generations, 5G will need to be a paradigm shift that includes very high carrier frequencies with massive bandwidths, extreme base station and device densities and unprecedented numbers of antennas. For this next generation networks, it will meet the new and challenging requirements that today's wireless access networks could not meet. Especially, multi-hop relaying in 5G wireless networking is foreseen to be a revolution in the way of connections with or without the direct intervention of the infrastructure. In traditional centralized schemes of connectivity, users connect exclusively through their nearest Base Station, or at most from a fixed relay station. However, 5G networks will use multi-hop relaying connection, i.e., besides the above traditional centralized schemes, they will also apply the new paradigm of Device-to-Device (D2D) networking, in which users are allowed to communicate peer-to-peer through direct links that do not necessarily involve the intervention of a Base Station. This new relaying approach can improve spectrum efficiency, better fairness in resource allocation, energy efficient usage, and etc. Meanwhile, this novel approach in 5G will face the challenge of distributed management of communications, subject to mobility, in which end-user terminals will play a more active role in the self-configuration of the network.

Owing to the recent advancements in the Internet of Things (IoT), an increasing number of IoT devices have led to frequency crowding in wireless networks. The low-complexity visible light communication (VLC) system is a promising solution for indoor frequency-crowded wireless networks owing to the ubiquity of light-emitting diodes (LEDs) and readily deployable, low-cost modulation methods. However, due to the inherent limitations of LED materials and growth of data from IoT applications, low-complexity VLC systems can barely boost the data throughput without adding complex modulations and circuits. This study aims to design and implement a spectrum-efficient, low-complexity VLC system to improve data throughput with very little cost to support indoor IoT applications. This system uses multiamplitude voltage to transmit multiple bit streams simultaneously, making it a novel system. However, it is not trivial to achieve this goal as the varying voltage can cause the LEDs to flicker. Therefore, we further propose a voltage-to-current amplifier circuit, which effectively mitigates the effects of changes in the LED’s brightness upon human eyes. Finally, we evaluate the system under different speeds, distances, and angles. Extensive experiments demonstrate promising results from the viewpoint of spectrum efficiency, throughput, bit-error rate, and user perception.