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Book ; Online: Airdrops

Messias, Johnnatan / Yaish, Aviv / Livshits, Benjamin

Giving Money Away Is Harder Than It Seems

2023

Abstract: Airdrops are used by blockchain applications and platforms to attract an initial user base, and to grow the user base over time. In the case of many airdrops, tokens are distributed to select users as a "reward" for interacting with the underlying ... ...

Abstract	Airdrops are used by blockchain applications and platforms to attract an initial user base, and to grow the user base over time. In the case of many airdrops, tokens are distributed to select users as a "reward" for interacting with the underlying platform, with a long-term goal of creating a loyal community that will generate genuine economic activity well after the airdrop has been completed. Although airdrops are widely used by the blockchain industry, a proper understanding of the factors contributing to an airdrop's success is generally lacking. In this work, we outline the design space for airdrops, and specify a reasonable list of outcomes that an airdrop should ideally result in. We then analyze on-chain data from several larger-scale airdrops to empirically evaluate the success of previous airdrops, with respect to our desiderata. In our analysis, we demonstrate that airdrop farmers frequently dispose of the lion's share of airdrops proceeds via exchanges. Our analysis is followed by an overview of common pitfalls that common airdrop designs lend themselves to, which are then used to suggest concrete guidelines for better airdrops. Comment: This research article is a work of scholarship and reflects the authors' own views and opinions. It does not necessarily reflect the views or opinions of any other person or organization, including the authors' employer. Readers should not rely on this article for making strategic or commercial decisions, and the authors are not responsible for any losses that may result from such use
Keywords	Computer Science - Cryptography and Security
Publishing date	2023-12-05
Publishing country	us
Document type	Book ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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Book ; Online: Cross-border Exchange of CBDCs using Layer-2 Blockchain

Gogol, Krzysztof / Messias, Johnnatan / Schlosser, Malte / Kraner, Benjamin / Tessone, Claudio

2023

Abstract: This paper proposes a novel multi-layer blockchain architecture for the cross-border trading of CBDCs. The permissioned layer-2, by relying on the public consensus of the underlying network, assures the security and integrity of the transactions and ... ...

Abstract	This paper proposes a novel multi-layer blockchain architecture for the cross-border trading of CBDCs. The permissioned layer-2, by relying on the public consensus of the underlying network, assures the security and integrity of the transactions and ensures interoperability with domestic CBDCs implementations. Multiple Layer-3s operate various Automated Market Makers (AMMs) and compete with each other for the lowest costs. To provide insights into the practical implications of the system, simulations of trading costs are conducted based on historical FX rates, with Project Mariana as a benchmark. The study shows that, even with liquidity fragmentation, a multi-layer and multi-AMM setup is more cost-efficient than a single AMM. Comment: This paper was presented at the Crypto Finance Conference (CfC) Academic Track 2024 in St. Moritz, Switzerland
Keywords	Computer Science - Cryptography and Security ; Computer Science - Social and Information Networks
Subject code	303
Publishing date	2023-12-22
Publishing country	us
Document type	Book ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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Book ; Online: Dissecting Bitcoin and Ethereum Transactions

Messias, Johnnatan / Pahari, Vabuk / Chandrasekaran, Balakrishnan / Gummadi, Krishna P. / Loiseau, Patrick

On the Lack of Transaction Contention and Prioritization Transparency in Blockchains

2023

Abstract: In permissionless blockchains, transaction issuers include a fee to incentivize miners to include their transactions. To accurately estimate this prioritization fee for a transaction, transaction issuers (or blockchain participants, more generally) rely ... ...

Abstract	In permissionless blockchains, transaction issuers include a fee to incentivize miners to include their transactions. To accurately estimate this prioritization fee for a transaction, transaction issuers (or blockchain participants, more generally) rely on two fundamental notions of transparency, namely contention and prioritization transparency. Contention transparency implies that participants are aware of every pending transaction that will contend with a given transaction for inclusion. Prioritization transparency states that the participants are aware of the transaction or prioritization fees paid by every such contending transaction. Neither of these notions of transparency holds well today. Private relay networks, for instance, allow users to send transactions privately to miners. Besides, users can offer fees to miners via either direct transfers to miners' wallets or off-chain payments -- neither of which are public. In this work, we characterize the lack of contention and prioritization transparency in Bitcoin and Ethereum resulting from such practices. We show that private relay networks are widely used and private transactions are quite prevalent. We show that the lack of transparency facilitates miners to collude and overcharge users who may use these private relay networks despite them offering little to no guarantees on transaction prioritization. The lack of these transparencies in blockchains has crucial implications for transaction issuers as well as the stability of blockchains. Finally, we make our data sets and scripts publicly available. Comment: This is a pre-print of our paper accepted to appear to the Financial Cryptography and Data Security 2023 (FC '23)
Keywords	Computer Science - Cryptography and Security
Subject code	650
Publishing date	2023-02-14
Publishing country	us
Document type	Book ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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Book ; Online: Understanding Blockchain Governance

Messias, Johnnatan / Pahari, Vabuk / Chandrasekaran, Balakrishnan / Gummadi, Krishna P. / Loiseau, Patrick

Analyzing Decentralized Voting to Amend DeFi Smart Contracts

2023

Abstract: Governance protocols define the means for amending or changing smart contracts without any centralized authority. They distribute the decision-making power to every user of the smart contract: Users vote on accepting or rejecting every change. In this ... ...

Abstract	Governance protocols define the means for amending or changing smart contracts without any centralized authority. They distribute the decision-making power to every user of the smart contract: Users vote on accepting or rejecting every change. In this work, we review and characterize decentralized governance in practice, using Compound and Uniswap -- two widely used governance protocols -- as a case study. We reveal a high concentration of voting power in both Compound and Uniswap: 10 voters hold together 57.86% and 44.72% of the voting power, respectively. Although proposals to change or amend the protocol receive, on average, a substantial number of votes (i.e., 89.39%) in favor within the Compound protocol, they require fewer than three voters to obtain 50% or more votes. We show that voting on Compound proposals can be unfairly expensive for small token holders, and we discover voting coalitions that can further marginalize these users.
Keywords	Computer Science - Cryptography and Security
Subject code	320
Publishing date	2023-05-28
Publishing country	us
Document type	Book ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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Book ; Online: Particle-Based Score Estimation for State Space Model Learning in Autonomous Driving

Singh, Angad / Makhlouf, Omar / Igl, Maximilian / Messias, Joao / Doucet, Arnaud / Whiteson, Shimon

2022

Abstract: Multi-object state estimation is a fundamental problem for robotic applications where a robot must interact with other moving objects. Typically, other objects' relevant state features are not directly observable, and must instead be inferred from ... ...

Abstract	Multi-object state estimation is a fundamental problem for robotic applications where a robot must interact with other moving objects. Typically, other objects' relevant state features are not directly observable, and must instead be inferred from observations. Particle filtering can perform such inference given approximate transition and observation models. However, these models are often unknown a priori, yielding a difficult parameter estimation problem since observations jointly carry transition and observation noise. In this work, we consider learning maximum-likelihood parameters using particle methods. Recent methods addressing this problem typically differentiate through time in a particle filter, which requires workarounds to the non-differentiable resampling step, that yield biased or high variance gradient estimates. By contrast, we exploit Fisher's identity to obtain a particle-based approximation of the score function (the gradient of the log likelihood) that yields a low variance estimate while only requiring stepwise differentiation through the transition and observation models. We apply our method to real data collected from autonomous vehicles (AVs) and show that it learns better models than existing techniques and is more stable in training, yielding an effective smoother for tracking the trajectories of vehicles around an AV. Comment: Accepted to CoRL 2022
Keywords	Computer Science - Robotics ; Computer Science - Machine Learning
Subject code	629
Publishing date	2022-12-13
Publishing country	us
Document type	Book ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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Article ; Online: Power of Judgment: The Significance of Kant's Philosophy for the Medical System Today.

Weigel, T F / Hanisch, E / Hanisch, A / Buia, A / Müller, L P / Messias, J / Hessler, C

Journal of surgical education

2018 Volume 76, Issue 1, Page(s) 4–8

Abstract: The ways of thinking in the manufacturing sciences are increasingly determining the rationality within medicine as a practical or action-based science. This "technological paradigm" infiltrates the field of medicine with the promise of increasing ... ...

Abstract	The ways of thinking in the manufacturing sciences are increasingly determining the rationality within medicine as a practical or action-based science. This "technological paradigm" infiltrates the field of medicine with the promise of increasing efficiency while simultaneously improving quality at various points in the system. Simple linear causal relationships generally need to be taken into account when manufacturing products. Even complex manufacturing processes can be broken down into the smallest units and, therefore, also be automated. The situation in complex systems such as the human body, however, is completely different. In order for doctors to be able to carry out their actions within this complex system, medicine as a science provides the physician with rules on the means that should be used to decide which remedy should be used, when and how. This judgment of which remedy should be used, when and how, what is known as the indication, is a central medical moment. This requires a power of judgment sharpened by experience. The indication, in turn, essentially determines the course of a disease and thus the quality of the treatment or the quality of result so often referred to these days.
MeSH term(s)	Judgment ; Medicine/standards ; Philosophy, Medical
Language	English
Publishing date	2018-08-12
Publishing country	United States
Document type	Journal Article
ZDB-ID	2277538-9
ISSN	1878-7452 ; 1931-7204
ISSN (online)	1878-7452
ISSN	1931-7204
DOI	10.1016/j.jsurg.2018.07.007
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Book ; Online: Selfish & Opaque Transaction Ordering in the Bitcoin Blockchain

Messias, Johnnatan / Alzayat, Mohamed / Chandrasekaran, Balakrishnan / Gummadi, Krishna P. / Loiseau, Patrick / Mislove, Alan

The Case for Chain Neutrality

2021

Abstract: Most public blockchain protocols, including the popular Bitcoin and Ethereum blockchains, do not formally specify the order in which miners should select transactions from the pool of pending (or uncommitted) transactions for inclusion in the blockchain. ...

Abstract	Most public blockchain protocols, including the popular Bitcoin and Ethereum blockchains, do not formally specify the order in which miners should select transactions from the pool of pending (or uncommitted) transactions for inclusion in the blockchain. Over the years, informal conventions or "norms" for transaction ordering have, however, emerged via the use of shared software by miners, e.g., the GetBlockTemplate (GBT) mining protocol in Bitcoin Core. Today, a widely held view is that Bitcoin miners prioritize transactions based on their offered "transaction fee-per-byte." Bitcoin users are, consequently, encouraged to increase the fees to accelerate the commitment of their transactions, particularly during periods of congestion. In this paper, we audit the Bitcoin blockchain and present statistically significant evidence of mining pools deviating from the norms to accelerate the commitment of transactions for which they have (i) a selfish or vested interest, or (ii) received dark-fee payments via opaque (non-public) side-channels. As blockchains are increasingly being used as a record-keeping substrate for a variety of decentralized (financial technology) systems, our findings call for an urgent discussion on defining neutrality norms that miners must adhere to when ordering transactions in the chains. Finally, we make our data sets and scripts publicly available. Comment: This is a pre-print of our paper accepted to appear to ACM IMC 2021
Keywords	Computer Science - Cryptography and Security
Publishing date	2021-10-22
Publishing country	us
Document type	Book ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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Article: Zinc and selenium accumulation and their effect on iron bioavailability in common bean seeds

de Figueiredo, Marislaine A / Jonathan J. Hart / Li Li / Luiz R.G. Guilherme / Messias J.B. de Andrade / Paulo F. Boldrin / Raymond P. Glahn

Plant physiology and biochemistry. 2017 Feb., v. 111

2017

Abstract: Common beans (Phaseolus vulgaris) are the most important legume crops. They represent a major source of micronutrients and a target for essential trace mineral enhancement (i.e. biofortification). To investigate mineral accumulation during seed ... ...

Abstract	Common beans (Phaseolus vulgaris) are the most important legume crops. They represent a major source of micronutrients and a target for essential trace mineral enhancement (i.e. biofortification). To investigate mineral accumulation during seed maturation and to examine whether it is possible to biofortify seeds with multi-micronutrients without affecting mineral bioavailability, three common bean cultivars were treated independently with zinc (Zn) and selenium (Se), the two critical micronutrients that can be effectively enhanced via fertilization. The seed mineral concentrations during seed maturation and the seed Fe bioavailability were analyzed. Common bean seeds were found to respond positively to Zn and Se treatments in accumulating these micronutrients. While the seed pods showed a decrease in Zn and Se along with Fe content during pod development, the seeds maintained relatively constant mineral concentrations during seed maturation. Selenium treatment had minimal effect on the seed accumulation of phytic acid and polyphenols, the compounds affecting Fe bioavailability. Zinc treatment reduced phytic acid level, but did not dramatically affect the concentrations of total polyphenols. Iron bioavailability was found not to be greatly affected in seeds biofortified with Se and Zn. In contrast, the inhibitory polyphenol compounds in the black bean profoundly reduced Fe bioavailability. These results provide valuable information for Se and Zn enhancement in common bean seeds and suggest the possibility to biofortify with these essential nutrients without greatly affecting mineral bioavailability to increase the food quality of common bean seeds.
Keywords	bioavailability ; biofortification ; black beans ; crops ; cultivars ; iron ; nutrients ; Phaseolus vulgaris ; phytic acid ; pods ; polyphenols ; seed maturation ; seeds ; selenium ; zinc
Language	English
Dates of publication	2017-02
Size	p. 193-202.
Publishing place	Elsevier Masson SAS
Document type	Article
ZDB-ID	742978-2
ISSN	1873-2690 ; 0981-9428
ISSN (online)	1873-2690
ISSN	0981-9428
DOI	10.1016/j.plaphy.2016.11.019
Database	NAL-Catalogue (AGRICOLA)

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Article ; Online: Zinc and selenium accumulation and their effect on iron bioavailability in common bean seeds.

de Figueiredo, Marislaine A / Boldrin, Paulo F / Hart, Jonathan J / de Andrade, Messias J B / Guilherme, Luiz R G / Glahn, Raymond P / Li, Li

Plant physiology and biochemistry : PPB

2016 Volume 111, Page(s) 193–202

Abstract	Common beans (Phaseolus vulgaris) are the most important legume crops. They represent a major source of micronutrients and a target for essential trace mineral enhancement (i.e. biofortification). To investigate mineral accumulation during seed maturation and to examine whether it is possible to biofortify seeds with multi-micronutrients without affecting mineral bioavailability, three common bean cultivars were treated independently with zinc (Zn) and selenium (Se), the two critical micronutrients that can be effectively enhanced via fertilization. The seed mineral concentrations during seed maturation and the seed Fe bioavailability were analyzed. Common bean seeds were found to respond positively to Zn and Se treatments in accumulating these micronutrients. While the seed pods showed a decrease in Zn and Se along with Fe content during pod development, the seeds maintained relatively constant mineral concentrations during seed maturation. Selenium treatment had minimal effect on the seed accumulation of phytic acid and polyphenols, the compounds affecting Fe bioavailability. Zinc treatment reduced phytic acid level, but did not dramatically affect the concentrations of total polyphenols. Iron bioavailability was found not to be greatly affected in seeds biofortified with Se and Zn. In contrast, the inhibitory polyphenol compounds in the black bean profoundly reduced Fe bioavailability. These results provide valuable information for Se and Zn enhancement in common bean seeds and suggest the possibility to biofortify with these essential nutrients without greatly affecting mineral bioavailability to increase the food quality of common bean seeds.
MeSH term(s)	Biofortification ; Biological Availability ; Biomass ; Caco-2 Cells ; Humans ; Iron/metabolism ; Minerals/metabolism ; Phaseolus/metabolism ; Phytic Acid/metabolism ; Polyphenols/metabolism ; Seeds/growth & development ; Seeds/metabolism ; Selenium/metabolism ; Zinc/metabolism
Chemical Substances	Minerals ; Polyphenols ; Phytic Acid (7IGF0S7R8I) ; Iron (E1UOL152H7) ; Selenium (H6241UJ22B) ; Zinc (J41CSQ7QDS)
Language	English
Publishing date	2016-11-28
Publishing country	France
Document type	Journal Article
ZDB-ID	742978-2
ISSN	1873-2690 ; 0981-9428
ISSN (online)	1873-2690
ISSN	0981-9428
DOI	10.1016/j.plaphy.2016.11.019
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Article ; Online: Manejo da irrigação utilizando sensor da umidade do solo alternativo Irrigation scheduling using alternative soil moisture sensor

Wellington A. de Freitas / Jacinto de A. Carvalho / R. A. Braga / Messias J. B. de Andrade

Revista Brasileira de Engenharia Agrícola e Ambiental - Agriambi, Vol 16, Iss 3, Pp 268-

2012 Volume 274

Abstract: Um sensor alternativo utilizando a medida da capacitância para determinação da umidade do solo foi desenvolvido e calibrado em laboratório, e avaliado por meio da comparação com tensiômetros, no manejo da irrigação da cultura do feijoeiro. Utilizou-se um ...

Abstract	Um sensor alternativo utilizando a medida da capacitância para determinação da umidade do solo foi desenvolvido e calibrado em laboratório, e avaliado por meio da comparação com tensiômetros, no manejo da irrigação da cultura do feijoeiro. Utilizou-se um delineamento inteiramente casualizado com 5 repetições e esquema fatorial com dois métodos de manejo (alternativo e tensiometria) além tensões de água no solo (20, 40 e 60 kPa). Observou-se que, independente do método empregado, a produção do feijoeiro foi maior quando submetido a tensão de 39 kPa; entretanto, o manejo da irrigação utilizando-se o método alternativo levou a um número maior de irrigações e também do volume de água aplicado, com consequente redução da eficiência do uso da água em comparação com o uso de tensiômetros. An alternative sensor using a capacitance measurement for determining soil moisture was developed and calibrated in the laboratory and evaluated by comparison with tensiometers in the irrigation of common bean. A completely randomized design was used with five replications and a factorial with two methods of management (alternative and tensiometer) and soil water tensions (20, 40 and 60 kPa). It was observed that regardless of the method, the bean yield was higher when subjected to stress of 39 kPa, however, irrigation management using the alternative method led to a greater number of irrigation and also the volume of water applied, with consequent reduction in water use efficiency compared to the use of tensiometers.
Keywords	capacitância ; feijão ; tensão de água no solo ; capacitance ; common bean ; soil water tension ; Agriculture (General) ; S1-972
Language	English
Publishing date	2012-01-01T00:00:00Z
Publisher	Universidade Federal de Campina Grande
Document type	Article ; Online
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