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151 results on '"Li, Sheng-Nan"'

1. Centralised or Decentralised? Data Analysis of Transaction Network of Hedera Hashgraph

Author

Amherd, Lucas, Li, Sheng-Nan, and Tessone, Claudio J.

Subjects
Computer Science - Cryptography and Security, Economics - General Economics
Abstract

An important virtue of distributed ledger technologies is their acclaimed higher level of decentralisation compared to traditional financial systems. Empirical literature, however, suggests that many systems tend towards centralisation as well. This study expands the current literature by offering a first-time, data-driven analysis of the degree of decentralisation of the platform Hedera Hashgraph, a public permissioned distributed ledger technology, employing data directly fetched from a network node. The results show a considerably higher amount of released supply compared to the release schedule and a growing number of daily active accounts. Also, Hedera Hashgraph exhibits a high centralisation of wealth and a shrinking core that acts as an intermediary in transactions for the rest of the network. However, the Nakamoto index and Theil index point to recent progress towards a more decentralised network.

Published
2023

3. Twisted by the Pools: Detection of Selfish Anomalies in Proof-of-Work Mining

Author

Li, Sheng-Nan, Campajola, Carlo, and Tessone, Claudio J.

Subjects
Computer Science - Cryptography and Security
Abstract

The core of many cryptocurrencies is the decentralised validation network operating on proof-of-work technology. In these systems, validation is done by so-called miners who can digitally sign blocks once they solve a computationally-hard problem. Conventional wisdom generally considers this protocol as secure and stable as miners are incentivised to follow the behaviour of the majority. However, whether some strategic mining behaviours occur in practice is still a major concern. In this paper we target this question by focusing on a security threat: a selfish mining attack in which malicious miners deviate from protocol by not immediately revealing their newly mined blocks. We propose a statistical test to analyse each miner's behaviour in five popular cryptocurrencies: Bitcoin, Litecoin, Monacoin, Ethereum and Bitcoin Cash. Our method is based on the realisation that selfish mining behaviour will cause identifiable anomalies in the statistics of miner's successive blocks discovery. Secondly, we apply heuristics-based address clustering to improve the detectability of this kind of behaviour. We find a marked presence of abnormal miners in Monacoin and Bitcoin Cash, and, to a lesser extent, in Ethereum. Finally, we extend our method to detect coordinated selfish mining attacks, finding mining cartels in Monacoin where miners might secretly share information about newly mined blocks in advance. Our analysis contributes to the research on security in cryptocurrency systems by providing the first empirical evidence that the aforementioned strategic mining behaviours do take place in practice.

Published
2022

9. Energy evolution and failure characteristics of single fissure carbonaceous shale under drying−wetting cycles

Author

LIU Xin-xi, LI Yu, FAN Zi-jian, LI Sheng-nan, WANG Wei-wei, and DONG Peng

Subjects
triaxial compression, single fissure carbonaceous shale, drying?wetting cycle, energy evolution, failure characteristics, Engineering geology. Rock mechanics. Soil mechanics. Underground construction, TA703-712
Abstract

In order to investigate the energy evolution and failure characteristics of carbonaceous shale containing single fissure under drying−wetting cycles, the intact carbonaceous shale samples and the carbonaceous shale samples with fissure angles of 30°, 45° and 60° were prepared. MTS815 rock mechanics test system was used to conduct triaxial compression tests under different drying−wetting cycles. The influence of drying−wetting cycles on the strength, failure mode and energy evolution of single fissure carbonaceous shale were studied. The results show that the elastic energy and dissipated energy at crack initiation stress, damage stress and peak stress present exponential relationships with drying-wetting cycles. The elastic energy and dissipated energy at crack initiation stress and dissipated energy at damage stress are less sensitive to drying−wetting cycle, while the sensitivities of elastic energy at damage stress, and elastic energy and dissipated energy at peak stress are relatively high. The failure mode of carbonaceous shale is dominated by drying−wetting cycle and fissure angle, in which the drying-wetting cycle is the main controlling factor, and the fissure angle is the secondary controlling factor. It is found that tensile shear failure occurs in dry rock sample with fissure angle of 30°, while the dry rock sample with fissure angle of 45°and 60° are subjected to shear failure. With the increase of the number of drying−wetting cycles, the macroscopic length of the main crack increases, the density of secondary cracks increases, and the failure mode transforms to shear-tension composite failure. With the increase of the number of drying−wetting cycles, the energy storage level at crack initiation stress Kci and the energy storage level at damage stress Kcd increase gradually. The higher the energy storage level at crack initiation and damage stress, the more likely the crack initiation and rock damage occur. Kcd can be used as a warning indicator of rock failure. A larger Kcd indicates that the rock is more vulnerable to failure.

Published
2022
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21. Reward Distribution in Proof-of-Stake Protocols: A Trade-Off Between Inclusion and Fairness

Author

Li, Sheng-Nan; https://orcid.org/0000-0002-2305-3186, Spychiger, Florian; https://orcid.org/0000-0001-6602-8450, Tessone, Claudio; https://orcid.org/0000-0001-7733-6221, Li, Sheng-Nan; https://orcid.org/0000-0002-2305-3186, Spychiger, Florian; https://orcid.org/0000-0001-6602-8450, and Tessone, Claudio; https://orcid.org/0000-0001-7733-6221

Abstract

Proof-of-Stake (PoS) variants provide an energy-efficient alternative to Proof-of-Work (PoW). However, it is not clear whether practical PoS implementations are fair with respect to wealth, stake, and reward distribution. In this paper, we analyse the fairness of the four well-known PoS platforms Tezos, Polkadot, Cardano, and Casper through a data-driven approach. For this, we collect data on stakes and rewards for all the four platforms over several years. We then apply four measures to study the fairness along different dimensions. We calculate the Gini coefficient to explore the wealth inequality, the Nakamoto coefficient to investigate the degree of decentralization, and the expectational and robust fairness of the stake-reward proportions, i.e., if the validators receive their fair share of the rewards given their stake share. We can show that there are dynamics of high wealth inequalities and stake centralization in all the systems with Polkadot being the exception. With respect to stake-reward fairness, the platforms differ in the distributions of deviations from the fair share, i.e., in Cardano and Tezos, the differences have a lower magnitue as many small validators participate. However, by examining specific outcomes, we can show that platforms with a limited validator set such as Polkadot and Casper tend to be fairer regarding the reward payoffs, but it is not possible for smaller validators to participate. This mechanism sheds light on a trade-off that the platforms face: the more inclusive (open) the validation process is designed, the unfairer the reward distribution tends to be. Our results allow us to conclude that the way of how PoS is implemented matters greatly for its fairness.

Published
2023

27. Stochastic Modelling of Selfish Mining in Proof-of-Work Protocols

Author

Schwarz-Schilling, Caspar, Li, Sheng-Nan, Tessone, Claudio; https://orcid.org/0000-0001-7733-6221, Schwarz-Schilling, Caspar, Li, Sheng-Nan, and Tessone, Claudio; https://orcid.org/0000-0001-7733-6221

Abstract

In blockchain-based systems whose consensus mechanisms resort to Proof-of-Work (PoW), it is expected that a miner’s share of total block revenue is proportional to their share of hashing power with respect to the rest of the network. The protocol relies on the immediate broadcast of blocks by miners, to earn precedence in peers’ local blockchains. However, a deviation from this strategy named selfish mining (SM), may lead miners to earn more than their “fair share”. In this paper, we introduce an agent-based model to simulate the dynamics of SM behaviour by a single miner as well as mining pools to understand the influence of (a) mining power distribution, (b) overlay network topology, (c) positioning of the selfish nodes within the peer to peer network. Our minimalistic model allows us to find that in high levels of latency, SM is always a more profitable strategy; our results are very robust to different network topologies and mining nodes’ centrality in the network. Moreover, the power-law distribution of the miners’ hashing power can make it harder for a selfish miner to be profitable. In addition, we analyze the effect of SM on system global efficiency and fairness. Our analysis confirms that SM is always more profitable for hashing powers representing more than one-third of the total computing power. Further, it also confirms that SM behaviour could cause a statistically significant high probability of continuously mined blocks opening the door for empirical verification of the phenomenon.

Published
2022

28. sj-docx-1-onc-10.1177_11795549221110522 – Supplemental material for Hysteroscopic Curettage Followed by Megestrol Acetate Plus Metformin as a Fertility-Sparing Treatment for Women with Atypical Endometrial Hyperplasia or Well-Differentiated Endometrioid Endometrial Carcinoma

Author

Jing, Chu-Yu, Li, Sheng-Nan, Shan, Bo-Er, Zhang, Wei, Tian, Wen-Juan, Ren, Yu-Lan, and Wang, Hua-Ying

Subjects
FOS: Clinical medicine, 111299 Oncology and Carcinogenesis not elsewhere classified
Abstract

Supplemental material, sj-docx-1-onc-10.1177_11795549221110522 for Hysteroscopic Curettage Followed by Megestrol Acetate Plus Metformin as a Fertility-Sparing Treatment for Women with Atypical Endometrial Hyperplasia or Well-Differentiated Endometrioid Endometrial Carcinoma by Chu-Yu Jing, Sheng-Nan Li, Bo-Er Shan, Wei Zhang, Wen-Juan Tian, Yu-Lan Ren and Hua-Ying Wang in Clinical Medicine Insights: Oncology

Published
2022
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34. Upregulation of OSBPL3 by HIF1A promotes colorectal cancer progression through activation of RAS signaling pathway

Author

Jiao, Hong-li, Weng, Bin-shu, Yan, Shan-shan, Lin, Zi-mo, Wang, Shu-yang, Chen, Xiao-ping, Liang, Guang-hua, Li, Xiao-Qing, Zhao, Wei-yi, Huang, Jia-Yi, Zhang, Dan, Zhang, Ling-jie, Han, Fang-yi, Li, Sheng-nan, Chen, Li-jie, Zhu, Jiong-hua, He, Wen-feng, Ding, Yan-qing, and Ye, Ya-ping

Subjects
Male, Mice, Nude, Fatty Acid-Binding Proteins, Models, Biological, Article, Cell Line, Tumor, Animals, Humans, lcsh:QH573-671, neoplasms, Mice, Inbred BALB C, Base Sequence, lcsh:Cytology, Middle Aged, Hypoxia-Inducible Factor 1, alpha Subunit, Prognosis, Colorectal cancer, digestive system diseases, Up-Regulation, Gene Expression Regulation, Neoplastic, Gene Knockdown Techniques, Disease Progression, ras Proteins, Female, Colorectal Neoplasms, Cell signalling, Signal Transduction
Abstract

Oxysterol-binding protein like protein 3 (OSBPL3) has been shown involving in the development of several human cancers. However, the relationship between OSBPL3 and colorectal cancer (CRC), particularly the role of OSBPL3 in the proliferation, invasion and metastasis of CRC remains unclear. In this study, we investigated the role of OSBPL3 in CRC and found that its expression was significantly higher in CRC tissues than that in normal tissues. In addition, high expression of OSBPL3 was closely related to poor differentiation, advanced TNM stage and poor prognosis of CRC. Further experiments showed that over-expression of OSBPL3 promoted the proliferation, invasion and metastasis of CRC in vitro and in vivo models. Moreover, we revealed that OSBPL3 promoted CRC progression through activation of RAS signaling pathway. Furthermore, we demonstrated that hypoxia induced factor 1 (HIF-1A) can regulate the expression of OSBPL3 via binding to the hypoxia response element (HRE) in the promoter of OSBPL3. In summary, Upregulation of OSBPL3 by HIF1A promotes colorectal cancer progression through activation of RAS signaling pathway. This novel mechanism provides a comprehensive understanding of both OSBPL3 and the RAS signaling pathway in the progression of CRC and indicates that the HIF1A–OSBPL3–RAS axis is a potential target for early therapeutic intervention in CRC progression.

Published
2020

37. Classification of helicopter’s typical flight state based on threshold

Author

Li Sheng-nan, Wang Jing-lin, Yang Le, and null ZhangShang-tian

Abstract

Dividing the 37 flying state of a certain line number helicopter. Firstly, dividing the helicopter rotation and single-engine flight. Secondly, performing preliminary state division for the remaining samlpes, the specific division of yaw angle, helicopter flight altitude and indicated air speed are different states, the least squares polynomial method is used for smoothing respectively. Calculating the extreme value of each parameter data, with the difference value of the extreme value of the parameter data being less than 10 as the limiting condition, dividing the original data segment into non-turning, level flight and steady speed state. The remaining sampling points are in the state of unsteady turning and non-level flight. Taking the difference value 0 as the limiting condition, further divide the non-steady speed and non-level flight state. Dividing the state of turning and non-turning, level flight, ascent and descent, steady speed, increase speed and deceleration state, which is the preliminary division state. Finally, dividing the near-ground and non-near-ground, classifying the helicopter status according to the height threshold, and analyze the accuracy of the classification results. The results show that this method is versatile, can quickly divide helicopters with different flight complexity, and has high accuracy.

Published
2021

41. Effect of Se-enriched Organic Fertilizers on Selenium Accumulation in Corn and Soil

Author

LI Sheng-nan, YUE Shi-zhong, LI Hua-fen, and QIAO Yu-hui

Subjects
inorganic chemicals, lcsh:GE1-350, corn, Se-enriched cow dung, selenium content, Se-enriched rice straw biochar, food and beverages, lcsh:Agriculture (General), lcsh:S1-972, lcsh:Environmental sciences
Abstract

The effect of two Se-enriched organic fertilizers (cow dung and rice straw biochar) on selenium accumulation of corn growing in selenium deficient soil was studied with pot experiment. The results showed that corn accumulated more selenium and the selenium was much easier to convert from root to shoot in the corn plant with the application of Se-enriched cow dung than Se-enriched rice straw biochar. With the application of more organic fertilizer such as 25 t·hm-2 Se-enriched cow dung or 40 t·hm-2 Se-enriched rice straw biochar, the accumulation of selenium and growth status of corn were getting better than the other treatments. At the same time, as the application amount of Se-enriched organic fertilizers (cow dung and rice straw biochar) increased, the total selenium content in the soil also increased, which positively correlated with each other.

Published
2015

44. Chinese herb mix Tiáo-Gēng-Tāng possesses antiaging and antioxidative effects and upregulates expression of estrogen receptors alpha and beta in ovariectomized rats

Author

Xu Lian-wei, Kluwe Lan, Zhang Ting-ting, Li Sheng-nan, Mou Yan-yan, Sang Zhen, Ma Jun, Lu Xiong, and Sun Zhuo-jun

Subjects
Other systems of medicine, RZ201-999
Abstract

Abstract Background Herb mixtures are widely used as an alternative to hormonal therapy in China for treatment of the menopausal syndrome. However, composition of these herb mixtures are complex and their working mechanism is often unknown. This study investigated the effect of Tiáo-Gēng-Tāng (TG-decoction), a Chinese herbal mixture extract, in balancing female hormones, regulating expression of estrogen receptors (ERs), and preventing aging-related tissue damage. Methods Ovariectomized 5-month-old female rats were used to model menopause and treated with either TG-decoction or conjugated estrogen for 8 weeks. Estradiol (E2), luteinizing hormone (LH) and follicle-stimulating hormone (FSH) were measured in serum and in the hypothalamus. Hypothalamic expression of estrogen receptor (ER) alpha and beta were studied by real-time PCR and western blotting. Total antioxidant capacity (T-AOC), oxidation indicator superoxide dismutase (SOD) activity and tissue damage parameter malondialdehyde (MDA) were measured using standard assays. Aging-related ultrastructural alterations in mitochondria were studied in all animals by transmission electron microscopy. Results TG-decoction-treatment elevated E2 and lowered FSH in serum of ovariectomized rats. The potency and efficacy of TG-decoction on the hypothalamus was generally weaker than that of conjugated estrogens. However, TG-decoction was superior in upregulating expression of ERα and β. TG-decoction increased hypothalamic SOD and T-AOC levels and decreased MDAlevels and mitochondrial damage in hypothalamic neurons. Conclusions TG-decoction balances female hormones similarly to conjugated estrogens but less effectively. However, it is superior in up regulating ERα and β and exhibits antioxidative antiaging activities. Whilst it shares similar effects with estrogen, TG-decoction also seems to have distinctive and more complex functions and activities.

Published
2011
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46. Uncovering the popularity mechanisms for Facebook applications

Author

Li, Sheng-Nan, Guo, Qiang, Yang, Kai, Liu, Jian-Guo, Zhang, Yi-Cheng, Li, Sheng-Nan, Guo, Qiang, Yang, Kai, Liu, Jian-Guo, and Zhang, Yi-Cheng

Abstract

Understanding the popularity dynamics of online application(App) is significant for the online social systems. In this paper, by dividing the Facebook Apps into different groups in terms of their popularities, we empirically investigate the popularity dynamics for different kinds of Facebook Apps. Then, taking into account the influence of cumulative and recent popularities on the user choice, we present a model to regenerate the growth of popularity for different App groups. The experimental results of 917 Facebook Apps show that as the popularities of Facebook Apps increase, the recent popularity plays more important role. Specifically, the recent popularity plays more important role in regenerating the popularity dynamics for more popular Apps, and the cumulative popularity plays more important role for unpopular Apps. We also conduct temporal analysis on the growth characteristic of individual App by comparing the increment at each time with the average of historical records. The results show that the growth of more popular App tends to fluctuate more greatly. Our work may shed some lights for deeply understanding the popularity mechanism for online applications.

Published
2018

47. Evolution properties of the community members for dynamic networks

Author

Yang, Kai, Guo, Qiang, Li, Sheng-Nan, Han, Jing-Ti, Liu, Jian-Guo, University of Zurich, and Liu, Jian-Guo

Subjects
10009 Department of Informatics, 000 Computer science, knowledge & systems, 3100 General Physics and Astronomy
Abstract

The collective behaviors of community members for dynamic social networks are significant for understanding evolution features of communities. In this Letter, we empirically investigate the evolution properties of the new community members for dynamic networks. Firstly, we separate data sets into different slices, and analyze the statistical properties of new members as well as communities they joined in for these data sets. Then we introduce a parameter φ to describe community evolution between different slices and investigate the dynamic community properties of the new community members. The empirical analyses for the Facebook, APS, Enron and Wiki data sets indicate that both the number of new members and joint communities increase, the ratio declines rapidly and then becomes stable over time, and most of the new members will join in the small size communities that is s≤10s≤10. Furthermore, the proportion of new members in existed communities decreases firstly and then becomes stable and relatively small for these data sets. Our work may be helpful for deeply understanding the evolution properties of community members for social networks.

Published
2017

48. Adsorption effect of ammonia by four fillings

Author

LI Sheng-nan, Hu Xiaozhen, He Kai, Lu Shaoyong, and Jin Xiangcan

Subjects
Ion exchange, Chemistry, chemistry.chemical_element, Sorption, Aquatic Science, Vermiculite, Pollution, Nitrogen, Ammonia, chemistry.chemical_compound, Adsorption, Environmental chemistry, Desorption, Earth and Planetary Sciences (miscellaneous), Zeolite, Water Science and Technology
Abstract

Nitrogen is one kind of important elements related to eutrophication of lakes. The removal of exterior pollution source and interior pollution source is significant for eutrophication control of lakes. Ammonia removal by fillings is an important ways for the control of exterior pollution source of lakes. The ammonia adsorption behavior of four kinds of fillings, such as savageness zeolite, haydite, vermiculite and soil were investigated. The main way of ammonia removal by fillings, the effects of solution pH and temperature on removal rate of ammonia were observed. The results indicated that there were significant differences between zeolite and other fillings, and the sorption efficiency in the order were zeolite, vermiculi, soil and haydite. The ion exchange function is the main way of removing ammonia by zeolite, zeolite has the worst sorption ability, whereas other three fillings have almost the same sorption and ion exchange capacities. In addition, adsorption capacities of these four fillings decreased as temperature increased between 15-35℃; as the pH values increased at the range of 3-9 the adsorption capacities of these four fillings increase too. All adsorption experiments reached equilibrium within six hours.

Published
2008

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