Lazy Contracts: Alleviating High Gas Costs by Secure and Trustless Off-chain Execution of Smart Contracts

Smart contracts are programs that are executed on the blockchain and can hold, manage and transfer assets in the form of cryptocurrencies. The contract's execution is then performed on-chain and is subject to consensus, i.e. every node on the blockchain network has to run the function calls and keep track of their side-effects. In most programmable blockchains, such as Ethereum, the notion of gas is introduced to prevent DoS attacks by malicious parties who might try to slow down the network by performing heavy computations. A fixed cost to each atomic operation, and the initiator of a function call pays the total gas cost as a transaction fee. This helps prevent DoS attacks, but the resulting fees are extremely high. For example, in 2022, on Ethereum alone, there has been a total gas usage of 1.77 Million ETH ~ 4.3 Billion USD. This thesis proposes "lazy contracts" as a solution to alleviate these costs. Our solution moves most of the computation off-chain, ensuring that each function call incurs only a tiny amount of gas usage, while preserving enough data on-chain to guarantee an implicit consensus about the state of the contract variables and ownership of funds. A complete on-chain execution of the functions will only be triggered in case two parties to the contract are in disagreement about the current state, which in turn can only happen if at least one party is dishonest. In such cases, our protocol can identify the dishonest party and penalize them by having them pay for the entire gas usage. Hence, no rational party has an incentive to act dishonestly. Finally, we perform extensive experiments over 160,735 real-world Solidity contracts that were involved in 9,055,492 transactions in January 2022--January 2023 on Ethereum and show that our approach reduces the overall gas usage by 55.4%, which amounts to an astounding saving of 109.9 Million USD in gas fees.Comment: 60 pages, 10 figure

High-Frequency Causality in the VIX Index and its derivatives: Empirical Evidence

In February 2018, the VIX index has seen its largest ever increase and has lead to significant losses for some major volatility related products. Despite many efforts, the precise underlying reasons are yet to be discovered. We study the role of linear causality in the VIX index and its derivatives during January and February 2018. Due to the shortcomings of statistical inferences for stochastic volatility models, the dynamics of the volatility expectation index VIX remain controversial. Leveraging intraday data, we discover novel empirical results describing their interaction. We find bidirectional causality between the VIX spot and the implied volatility of Standard and Poors 500 options, suggesting a volatility feedback effect. The spot index tends to be lagging its own futures, while the vector autoregressions error correction mechanism reveals a significant mean-reverting equilibrium relationship. The evidence is consistent with recent theories indicating that implied volatility has stronger feedback than realized volatility. The paper reveals a retroactive information flow and highlights novel insights for the market microstructure of VIX derivatives and their related SnP 500 options

Rational Micro-Nano Structuring for Thin Film Evaporation

Heat management in electronics and photonics devices is a critical challenge that impedes the accelerated breakthrough in these fields. Among approaches for heat dissipation, thin film evaporation with micro/nano structures has been one of the most promising approaches that can address future technological demand. The geometry and dimension of these micro/nano structures directly govern the interfacial heat flux. Here, through theoretical and experimental analysis, we find that there is an optimal dimension of micro/nano structures that maximizes the interfacial heat flux by thin film evaporation. This optimal criterion is a consequence of two opposing phenomena: non-uniform evaporation flux across a liquid meniscus (divergent mass flux near three phase contact line) and the total liquid area exposed for evaporation. This general criterion is independent of the solid material and thermo-physical properties of the cooling liquid. This study paves the path for development of high-performance thermal management systems.Mechanical Engineering, Department o

Nonstructural Vulnerability Functions for Building Categories

Nonstructural building components account for the majority of building construction cost and as a result, their damage in earthquakes can dominate repair costs. The relationships between earthquake excitation and repair cost for nonstructural components are sometime depicted in seismic vulnerability functions. These relationships can be used at the level of individual buildings, as in ATC-58 (Applied Technology Council 2012), but there is also a need for such relationships at the level of building categories, for use in societal-level risk modeling. This work addresses the latter problem. There are several ways to address the problem: 1) by empirical means (relating aggregate nonstructural loss to ground motion through regression analysis); 2) by analytical means (relating structural response to component-level damage, which is then related to repair costs); and 3) by expert opinion. This work deals with analytical means. There is a growing library of component-level fragility functions for nonstructural components, and at least in the United States, an extensive database of costs for performing repairs. These enable the development of analytical relationships between structural response and nonstructural loss. Our intention is to produce and illustrate a method for developing broadly applicable analytical seismic vulnerability functions for non-structural components of buildings defined only by broad categories of material, lateral force-resisting system, and height. The methodology is developed with collaboration and supervision of Professor Keith Porter at the University of Colorado Boulder and is intended for use as a guideline by the Global Earthquake Model. A central challenge in such an effort is that the source data can be highly detailed. These detailed elements must be aggregated to systems and thence to all nonstructural components. So we (the present author with assistance and feedback form collaborators in the GEM project) have developed the methodology with a broad-brush approach, using cost manuals to identify the 4 or 5 systems that contribute the most cost to a typical building of the given category, and determining from a modest sample of buildings within the category of interest the detailed components that appear to be most common within those systems

Successful Desensitization ofEfavirenz in an 8 -year-Old HIV-Positive Child

Abstract: Background & Aims: Allergic reaction is a common side effect of Efavirenz and drug replacement may not be an option to physicians. Here, a successful drug desensitization experiment on an 8-year-old female child over a period of 9 days is reported. Case presentation: The patient was an 8-year old female child with HIV in Kerman, Iran who had been received oral efavirenz together with lamivudine and zidovudine. The patient had showed allergic reaction in the form of skin rashes and itchy skin right one hour after the use of the medication. Since replacing efavirenz with other medications was not an option, in this case, we developed a 9- day drug desensitization strategy in which on the first day, 300 mg of efavirenz was dissolved in 10 ml water and was given to the patient. The medication was doubled every day since after. After 9 days of drug administration, the patient was successfully desensitized toward the medication. The patient was monitored for 3 months and had no problem while using efavirenz together with lamivudine and zidovudine. Conclusion: This drug desensitization protocol for efavirenz can be recommended to physicians when medication replacement may not be an option due to the lack of drug availability. Keywords: Efavirenz, Desensitization, Drug hypersensitivit

Yarn properties developments with diagonally slotted roller on ring spinning machine

To develop new ring spinning process, the diagonally slotted rollers (DSR) of various angles (15°, 30° and 45°) have been designed, manufactured and then fitted below and parallel to the top front draft rollers of a ring spinning frame. The yarn samples of 20 tex are produced in conventional ring spinning, Solo spinning and newly developed DSR spinning methodologies. In ring spinning process, the escaped fibre ends from the strand surface in the spinning triangle do not entangle with other fibres when the yarn is twisted and therefore they make the yarn hairs. In DSR rollers, the slot walls provide a condition to prevent escaping of fibre ends from the strand and keep the fibre ends on the strand surface in the twisting process. The experimental results show that the yarns produced with DSR roller of 30° slot angle (DSR30) have less S3 value of hairiness and a cleaner appearance than conventional ring-spun yarns. The hairiness of the yarns of DSR30 and Solo spinning processes do not have a statistically significant difference. Also, the improvement in ring-spun yarn tenacity and elongation is much larger for newly developed DSR spinning process in comparison with Solo spinning process. Consequently, it is concluded that the DSR spinning methodology improves the hairiness and mechanical properties of ring-spun yarns even more successfully in comparison with the Solo spinning method

Effects of oral, smoked, and vaporized cannabis on endocrine pathways related to appetite and metabolism: a randomized, double-blind, placebo-controlled, human laboratory study.

As perspectives on cannabis continue to shift, understanding the physiological and behavioral effects of cannabis use is of paramount importance. Previous data suggest that cannabis use influences food intake, appetite, and metabolism, yet human research in this regard remains scant. The present study investigated the effects of cannabis administration, via different routes, on peripheral concentrations of appetitive and metabolic hormones in a sample of cannabis users. This was a randomized, crossover, double-blind, placebo-controlled study. Twenty participants underwent four experimental sessions during which oral cannabis, smoked cannabis, vaporized cannabis, or placebo was administered. Active compounds contained 6.9 ± 0.95% (~50.6 mg) ∆9-tetrahydrocannabinol (THC). Repeated blood samples were obtained, and the following endocrine markers were measured: total ghrelin, acyl-ghrelin, leptin, glucagon-like peptide-1 (GLP-1), and insulin. Results showed a significant drug main effect (p = 0.001), as well as a significant drug × time-point interaction effect (p = 0.01) on insulin. The spike in blood insulin concentrations observed under the placebo condition (probably due to the intake of brownie) was blunted by cannabis administration. A significant drug main effect (p = 0.001), as well as a trend-level drug × time-point interaction effect (p = 0.08) was also detected for GLP-1, suggesting that GLP-1 concentrations were lower under cannabis, compared to the placebo condition. Finally, a significant drug main effect (p = 0.01) was found for total ghrelin, suggesting that total ghrelin concentrations during the oral cannabis session were higher than the smoked and vaporized cannabis sessions. In conclusion, cannabis administration in this study modulated blood concentrations of some appetitive and metabolic hormones, chiefly insulin, in cannabis users. Understanding the mechanisms underpinning these effects may provide additional information on the cross-talk between cannabinoids and physiological pathways related to appetite and metabolism

Profit-Influencing Factors in Orthopedic Surgery: An Analysis of Costs and Reimbursements.

The aging population and the associated demand for orthopedic surgeries are increasing health costs. Although the Diagnostic Related Groups (DRG) system was introduced to offer incentives for hospitals, concerns remain that reimbursements for older and frail patients do not cover all hospital expenses. We investigated further: (1) Does age influence net financial results in orthopedic surgery? (2) Are there patient or surgical factors that influence results? This retrospective, monocentric study compares costs and reimbursements for orthopedic patients in a tertiary care hospital in Switzerland between 2015 and 2017. The data of 1230 patients were analyzed. Overall, the net results for the hospital were positive, despite 19.5% of patients being treated at a loss. We did not find any correlation between age and profitability (p = 0.61). Patient-related factors associated with financial losses were female sex (p < 0.001) and diabetes (p = 0.013). Patients free of serious comorbidities (p = 0.012) or with a higher cost weight (p < 0.001) were more often profitable. A longer length of stay was associated with higher losses (p < 0.001). This is the first study to address the Swiss DRG reimbursement system in a broad orthopedic population, while also analyzing specific patient and surgical factors. Overall, the reimbursement system is fair, but could better account for certain interventions

Harm reduction and abstinence-based models for treatment of substance use disorders during the COVID-19 pandemic : a global perspective

M.F. is an employee of the US Federal Government and is supported by National Institutes of Health (NIH) intramural funding (ZIA-DA000635 and ZIA-AA000218), outside of this research.The COVID-19 pandemic has significantly affected treatment services for people with substance use disorders (SUDs). Based on the perspectives of service providers from eight countries, we discuss the impact of the pandemic on SUD treatment services. Although many countries quickly adapted in provision of harm reduction services by changes in policy and service delivery, some went into a forced abstinence-based strategy. Similarly, disruption of abstinence-based approaches such as therapeutic communities has been reported. Global awareness is crucial for responsible management of SUDs during the pandemic, and the development of international health policy guidelines is an urgent need in this area.Publisher PDFPeer reviewe