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Cooperation among an anonymous group protected Bitcoin during failures of decentralization

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arXiv 2022年

作者： Blackburn, Alyssa Huber, Christoph Eliaz, Yossi Shamim, Muhammad S. Weisz, David Seshadri, Goutham Kim, Kevin Hang, Shengqi Aiden, Erez Lieberman The Center for Genome Architecture Baylor College of Medicine HoustonTX77030 United States Department of Molecular and Human Genetics Baylor College of Medicine HoustonTX United States Center for Theoretical Biological Physics Rice University HoustonTX77030 United States Institute for Markets and Strategy WU Vienna University of Economics and Business Vienna Austria Department of Physics University of Houston HoustonTX77204 United States Medical Scientist Training Program Baylor College of Medicine HoustonTX United States Department of Computer Science Rice University HoustonTX77030 United States

Bitcoin is a digital currency designed to rely on a decentralized, trustless network of anonymous agents. Using a pseudonymous-address-linking procedure that achieves >99% sensitivity and >99% specificity, we reveal that between launch (1/3/2009), and when the price reached $1 (2/9/2011), most bitcoin was mined by only sixty-four agents. This was due to the rapid emergence of Pareto distributions in bitcoin income, producing such extensive resource centralization that almost all contemporary bitcoin addresses can be connected to these top agents by a chain of six transactions. Centralization created a social dilemma. Attackers could routinely exploit bitcoin via a "51% attack", making it possible for them to repeatedly spend the same bitcoins. Yet doing so would harm the community. Strikingly, we find that potential attackers always chose to cooperate instead. We model this dilemma using an N-player Centipede game in which anonymous players can choose to exploit, and thereby undermine, an appreciating good. Combining theory and economic experiments, we show that, even when individual payoffs are unchanged, cooperation is more frequent when the game is played by an anonymous group. Although bitcoin was designed to rely on a decentralized, trustless network of anonymous agents, its early success rested instead on cooperation among a small group of altruistic founders. © 2022, CC BY.

关键词： Pareto principle

Blending effects of boron carbide and lanthanum(III) oxide reinforcements on the structural, physical, mechanical, and radiation shielding properties of 316L-stainless steel composites for nuclear applications

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Annals of Nuclear Energy 2025年 221卷

作者： ALMisned, Ghada Yayla, Nihal Albayrak, M.Gökhan Güler, Ömer Baykal, Duygu Sen Alkarrani, Hessa Tekin, H.O. Department of Physics College of Science Princess Nourah Bint Abdulrahman University P.O. Box 84428 Riyadh11671 Saudi Arabia Munzur University Department of Strategic Raw Materials and Advanced Technology Applications Tunceli Turkey Fırat University Metallurgical and Materials Engineering Department Engineering Faculty Elazığ Turkey Rare Earth Elements Application and Research Center Munzur University Tunceli62000 Turkey Istanbul Nisantasi University Faculty of Engineering and Architecture Mechatronics Engineering Istanbul34398 Turkey Research Institute for Medical and Health Sciences University of Sharjah Sharjah Sharjah27272 United Arab Emirates Medical Diagnostic Imaging Department College of Health Sciences University of Sharjah Sharjah27272 United Arab Emirates Istinye University Faculty of Engineering and Natural Sciences Computer Engineering Department Istanbul34396 Turkey

Four composite samples were fabricated, maintaining 10 % B4C and varying La2O3 content from 0 % to 20 %. X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), and Energy Dispersive X-ray Spectroscopy (EDX) analyses confirmed the successful incorporation of reinforcements, preserving the austenitic structure of 316L-SS. Elastic modulus calculations revealed a gradual reduction from 225.0 GPa to 215.0 GPa with increasing La2O3 due to clustering and reduced homogeneity. Gamma-ray shielding properties demonstrated significant improvements, particularly at low and intermediate photon energies, with Sample 4 with 20 % La2O3 addition, achieving a 13.6 % higher linear attenuation coefficients (LAC) at 0.015 MeV. Neutron shielding highlighted Sample 4 as one of the most effective materials, outperforming conventional alloys. This study demonstrates the potential of 316L Stainless-Steel (316L-SS) + B4C + La2O3 composites as multifunctional materials for radiation-intensive applications, offering superior attenuation and structural stability. It can be concluded that optimization of reinforcement distribution would play an important role in balancing mechanical and shielding performance in next-generation nuclear materials. © 2025 Elsevier Ltd

关键词： Reactor shielding

A Fast and Compact Invertible Sketch for Network-Wide Heavy Flow Detection

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arXiv 2019年

作者： Tang, Lu Huang, Qun Lee, Patrick P.C. Department of Computer Science and Engineering Chinese University of Hong Kong Hong Kong State Key Lab of Computer Architecture Institute of Computing Technology Chinese Academy of Sciences

Fast detection of heavy flows (e.g., heavy hitters and heavy changers) in massive network traffic is challenging due to the stringent requirements of fast packet processing and limited resource availability. Invertible sketches are summary data structures that can recover heavy flows with small memory footprints and bounded errors, yet existing invertible sketches incur high memory access overhead that leads to performance degradation. We present MV-Sketch, a fast and compact invertible sketch that supports heavy flow detection with small and static memory allocation. MV-Sketch tracks candidate heavy flows inside the sketch data structure via the idea of majority voting, such that it incurs small memory access overhead in both update and query operations, while achieving high detection accuracy. We present theoretical analysis on the memory usage, performance, and accuracy of MV-Sketch in both local and network-wide scenarios. We further show how MV-Sketch can be implemented and deployed on P4-based programmable switches subject to hardware deployment constraints. We conduct evaluation in both software and hardware environments. Trace-driven evaluation in software shows that MV-Sketch achieves higher accuracy than existing invertible sketches, with up to 3.38× throughput gain. We also show how to boost the performance of MV-Sketch with SIMD instructions. Furthermore, we evaluate MV-Sketch on a Barefoot Tofino switch and show how MV-Sketch achieves line-rate measurement with limited hardware resource overhead. Copyright © 2019, The Authors. All rights reserved.

关键词： Memory architecture

Block-groups and Hall relations

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arXiv 2020年

作者： Gaysin, Azza M. Volkov, Mikhail V. Department of Algebra Faculty of Mathematics and Physics Charles University Sokolovska 83 Praha 8186 00 Czech Republic Chair of Algebra and Theoretical Computer Science Institute of Natural Sciences and Mathematics Ural Federal University Lenina 51 Ekaterinburg620000 Russia

A binary relation on a finite set is called a Hall relation if it contains a permutation of the set. Under the usual relational product, Hall relations form a semigroup which is known to be a block-group, that is, a semigroup with at most one idempotent in each R-class and each L -class. Here we show that in a certain sense, the converse is true: every block-group divides a semigroup of Hall relations on a finite *** Codes 20M20 20M30 Copyright © 2020, The Authors. All rights reserved.

关键词： Set theory

Singular Value Decomposition and Neural Networks

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arXiv 2019年

作者： Bermeitinger, Bernhard Hrycej, Tomas Handschuh, Siegfried Chair of Data Science Institute of Computer Science University of St.Gallen St.Gallen Switzerland University Passau Passau Germany

Singular Value Decomposition (SVD) constitutes a bridge between the linear algebra concepts and multi-layer neural networks—it is their linear analogy. Besides of this insight, it can be used as a good initial guess for the network parameters, leading to substantially better optimization results. Copyright © 2019, The Authors. All rights reserved.

关键词： Singular value decomposition

Assessment of PM2.5-associated mortality burden among the elderly: Insights into demographic, socio-economic, and geographic factors

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Air Quality, Atmosphere & Health 2024年第7期17卷 1535-1545页

作者： Sharma, Ayushi Hsiao, Hsi-yu Liu, Jia-Yi Lung, Shih-Chun Candice Su, Huey-Jen Shen, Ching-Fen Chen, Nai-Tzu Wu, Pei-Chih Lin, Cheng-Yu Liang, Sheng-Fu Cheng, Tain-Junn Chan, Ta-Chien Tsay, Yaw-Shyan Chung, Hsin-Ying Wang, Yu-Chun Department of Environmental Engineering College of Engineering Chung Yuan Christian University Taoyuan Taiwan Department of Civil Engineering College of Engineering Chung Yuan Christian University Taoyuan Taiwan Research Center for Environmental Changes Academia Sinica Taipei City Taiwan Department of Environmental and Occupational Health National Cheng Kung University Tainan City Taiwan National Cheng Kung University Hospital Pediatrics Office Tainan City Taiwan Department of Green Energy and Environmental Resources Chang Jung Christian University Tainan City Taiwan Sleep Medicine Center College of Medicine National Cheng Kung University Hospital National Cheng Kung University Tainan Taiwan Department of Computer Science and Information Engineering & Institute of Medical Informatics National Cheng Kung University Tainan City Taiwan Department of Neurology and Occupational Medicine Chi Mei Medical Center Tainan City Taiwan School of Medicine College of Medicine National Sun Yat-Sen University Kaohsiung City Taiwan Research Center for Humanities and Social Sciences Academia Sinica Taipei City Taiwan Department of Architecture National Cheng Kung University Tainan City Taiwan Department of Plant Industry National Pingtung University of Science and Technology Tainan City Taiwan

Since long-term exposure to PM2.5 is a growing concern in Taiwan, therefore, our study aimed to investigate the association between different PM2.5 concentrations and cause-specific mortalities, as well as explore the influence of demographic, socio-economic, and geographic determinants on mortality. Utilizing a Distributed Lag Non-Linear Model (DLNM), we estimated the PM2.5-attributable mortality burden among the elderly population (above 65 years) in Taiwan from 2005 to 2018. Our analysis considered various thresholds defined by the World Health Organization (WHO) to assess the impact of PM2.5 concentrations, ranging from standard Air Quality Guidelines (AQG) levels (0–15 μg/m3) to higher interim targets (up to 80 μg/m3). Our study reveals that achieving AQG levels (< 15 μg/m3) in Taiwan could potentially prevent 5571 elderly deaths, including 889 deaths from CVDs, 934 deaths from RTIs, and 680 deaths from chronic diseases. We observed a rapid increase in attributable deaths at lower PM2.5 concentrations, with a subsequent marginal increase at higher levels of exposure. We also identified several factors that modify the effects of PM2.5 exposures among elderly. For example, we found that higher elderly population ratios and high-income households were associated with an elevated risk of PM2.5-related deaths. In contrast, higher social welfare expenditure, better availability of medical practitioners per square kilometer, and higher forest-to-land ratios were associated with positive effects, indicating their potential in reducing mortality risk. This study fills a knowledge gap by examining the health consequences of varying PM2.5 levels and explored the complex interplay between demographic, socio-economic, and geographic factors in relation to PM2.5-related mortality.

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A Comparison of Machine Learning Algorithms for Fall Detection using Wearable Sensors

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A Comparison of Machine Learning Algorithms for Fall Detecti...

International Conference on Artificial Intelligence in Information and Communication (ICAIIC)

作者： Nicolas Zurbuchen Pascal Bruegger Adriana Wilde Institute of Complex Systems (iCoSys) School of Engineering and Architecture of Fribourg Switzerland HES-SO University of Applied Sciences and Arts Western Switzerland Fribourg Switzerland Centre for Health Technologies (CHT) School of Electronics and Computer Science University of Southampton Southampton United Kingdom

ISBN: (数字)9781728149851

ISBN: (纸本)9781728149868

The proportion of people 60 years old and above is expected to double globally to reach 22 % by 2050. This creates societal challenges such as the increase of age-related illnesses and the need for caregivers. Falls are a major threat for the elderly, often causing serious injuries especially when the fallen person stays on the ground for a long time without assistance. This paper presents the development of a Fall Detection System (FDS) using an accelerometer combined with a gyroscope worn at the waist. Data come from SisFall, a publicly available dataset containing records of Activities of Daily Living and falls. We compared five Machine Learning algorithms. We first applied preprocessing and a feature extraction stage before using five Machine Learning algorithms, allowing us to compare them. Ensemble learning algorithms such as Random Forest and Gradient Boosting have the best performance, with a Sensitivity and Specificity both close to 99%.

关键词： Feature extraction Sensors Legged locomotion Senior citizens Machine learning algorithms Accelerometers Biomedical monitoring

The essential deployment metamodel: A systematic review of deployment automation technologies

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arXiv 2019年

作者： Wurster, Michael Breitenbücher, Uwe Falkenthal, Michael Krieger, Christoph Leymann, Frank Saatkamp, Karoline Soldani, Jacopo Institute of Architecture of Application Systems University of Stuttgart Stuttgart Germany Department of Computer Science University of Pisa Pisa Italy

In recent years, a plethora of deployment technologies evolved, many following a declarative approach to automate the delivery of software components. Even if such technologies share the same purpose, they differ in features and supported mechanisms. Thus, it is difficult to compare and select deployment automation technologies as well as to migrate from one technology to another. Hence, we present a systematic review of declarative deployment technologies and introduce the Essential Deployment Metamodel (EDMM) by extracting the essential parts that are supported by all these technologies. Thereby, the EDMM enables a common understanding of declarative deployment models by facilitating the comparison, selection, and migration of technologies. Moreover, it provides a technology-independent baseline for further deployment automation research. Copyright © 2019, The Authors. All rights reserved.

关键词： Automation

SMART project management for SMART cities: Analyzing critical factors affecting trust among Virtual Project Teams 6

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SMART project management for SMART cities: Analyzing critica...

6th HCT Information Technology Trends, ITT 2019

作者： Kaur, Sukhwant Akre, Vishwesh Arif, Mohammed University of Ontario Institute of Technology Durham College-School of Business IT and Technology ON Canada Computer and Information Science Higher Colleges of Technology Dubai Women's Dubai United Arab Emirates School Architecture and Built Environment Sustainability and Construction Futures Faculty of Science and Engineering University of Wolverhampton United Kingdom

ISBN: (纸本)9781728150611

SMART cities suggest a domain that attracts an increasing scientific, political and economic attention. Smart Cities have been characterised and defined by a number of factors including sustainability, economic development and a high quality of life. Enhancing these factors can be achieved through infrastructure (physical capital), human capital, social capital and ICT infrastructure. It requires ambitious projects to transform entire urban areas through master planning and infrastructure development. This required SMART project management. In order to accomplish the goals of SMART project management, the construction industries have to rely on multi-disciplinary project teams having varied expertise. Majority of these companies have adopted virtual teams for their business activities. These virtual teams work at global level and face a number of challenges that can have an impact on team effectiveness. This research paper focuses on classification of smart cities and key challenges faced by the virtual project teams. Further to this, this paper reviews existing international literature to identify the variables affecting trust among virtual team members in construction sector of Middle East. The variables are then grouped together to form factors after understanding their definitions and commonalities among them. This research highlights the importance of these factors to project managers of smart city projects and it would be beneficial to Project Managers of Architectural/Engineering/Construction Companies as well as that of other sectors by facilitating them to know the actions required for better team collaboration in virtual teams. This may lead to greater team performance and individual learning. © 2019 IEEE.

关键词： Smart city