scholarly journals k-root-n: An Efficient Algorithm for Avoiding Short Term Double-Spending Alongside Distributed Ledger Technologies Such as Blockchain

2020 ◽  
Author(s):  
Zvi Schreiber
Keyword(s):  
High Probability ◽  
Due Diligence ◽  
Short Term ◽  
Byzantine Faults ◽  
Global Consensus ◽  
Distributed Ledger ◽  
Velocity Of Money ◽  
Very High ◽  
Birthday Paradox

Blockchains such as the bitcoin blockchain depend on reaching a global consensus on the distributed ledger; therefore, they suffer from well know scalability problems. This paper proposes an algorithm that avoids double-spending in the short term with just O(√n) messages; each node receiving money off-chain performs the due diligence of consulting k√n random nodes to check if any of them is aware of double-spending. Two nodes receiving double-spent money will in this way consult at least one common node with very high probability, due to the ‘birthday paradox’, and any common honest node consulted will detect the fraud. Since the velocity of money in the real world has coins circulating through at most a few wallets per day, the size of the due diligence communication is small in the short term. This `k-root-n’ algorithm is suitable for an environment with synchronous or asynchronous (but with fairly low latency) communication and with Byzantine faults. The presented k-root-n algorithm should be practical to avoid double-spending with arbitrarily high probability, while feasibly coping with the throughput of all world commerce. It is resistant to Sybil attacks even beyond 50% of nodes. In the long term, the k-root-n algorithm is less efficient. Therefore, it should preferably be used as a complement and not a replacement to a global distributed ledger technology.

scholarly journals k-Root-n: An Efficient Algorithm for Avoiding Short Term Double-Spending Alongside Distributed Ledger Technologies such as Blockchain

Information ◽  
2020 ◽  
Vol 11 (2) ◽  
pp. 90 ◽  
Author(s):  
Zvi Schreiber
Keyword(s):  
High Probability ◽  
Due Diligence ◽  
Short Term ◽  
Byzantine Faults ◽  
Global Consensus ◽  
Distributed Ledger ◽  
Velocity Of Money ◽  
Very High ◽  
Birthday Paradox

Blockchains such as the bitcoin blockchain depend on reaching a global consensus on the distributed ledger; therefore, they suffer from well-known scalability problems. This paper proposes an algorithm that avoids double-spending in the short term with just O(√n) messages instead of O(n); each node receiving money off-chain performs the due diligence of consulting k√n random nodes to check if any of them is aware of double-spending. Two nodes receiving double-spent money will in this way consult at least one common node with very high probability, because of the ‘birthday paradox’, and any common honest node consulted will detect the fraud. Since the velocity of money in the real world has coins circulating through at most a few wallets per day, the size of the due diligence communication is small in the short term. This ‘k-root-n’ algorithm is suitable for an environment with synchronous or asynchronous (but with fairly low latency) communication and with Byzantine faults. The presented k-root-n algorithm should be practical to avoid double-spending with arbitrarily high probability, while feasibly coping with the throughput of all world commerce. It is resistant to Sybil attacks even beyond 50% of nodes. In the long term, the k-root-n algorithm is less efficient. Therefore, it should preferably be used as a complement, and not a replacement, to a global distributed ledger technology.

Positive Emotions

2009 ◽  
pp. 12-24 ◽  
Author(s):  
Michael A. Cohn ◽  
Barbara L. Fredrickson
Keyword(s):  
Positive Emotions ◽  
Well Being ◽  
Life Outcomes ◽  
Short Term ◽  
Future Success ◽  
Broaden And Build Theory ◽  
Mental And Physical Health ◽  
Very High ◽  
Future Growth

Positive emotions include pleasant or desirable situational responses, ranging from interest and contentment to love and joy, but are distinct from pleasurable sensation and undifferentiated positive affect. These emotions are markers of people's overall well-being or happiness, but they also enhance future growth and success. This has been demonstrated in work, school, relationships, mental and physical health, and longevity. The broaden-and-build theory of positive emotions suggests that all positive emotions lead to broadened repertoires of thoughts and actions and that broadening helps build resources that contribute to future success. Unlike negative emotions, which are adapted to provide a rapid response to a focal threat, positive emotions occur in safe or controllable situations and lead more diffusely to seeking new resources or consolidating gains. These resources outlast the temporary emotional state and contribute to later success and survival. This chapter discusses the nature of positive emotions both as evolutionary adaptations to build resources and as appraisals of a situation as desirable or rich in resources. We discuss the methodological challenges of evoking positive emotions for study both in the lab and in the field and issues in observing both short-term (“broaden”) and long-term (“build”) effects. We then review the evidence that positive emotions broaden perception, attention, motivation, reasoning, and social cognition and ways in which these may be linked to positive emotions' effects on important life outcomes. We also discuss and contextualize evidence that positive emotions may be detrimental at very high levels or in certain situations. We close by discussing ways in which positive emotions theory can be harnessed by both basic and applied positive psychology research.

scholarly journals Long- and Short-Term Changes of the Structure of Macrophytes in Lake Piaseczno in Relation to Land Use in the Łęczna-Włodawa Lakeland (Poland)

2013 ◽  
Vol 15 (2) ◽  
pp. 101-110
Author(s):  
Joana Sender ◽  
Weronika Maślanko
Keyword(s):  
Land Use ◽  
Aquatic Plants ◽  
Short Term ◽  
Main Interest ◽  
Central European ◽  
Macrophyte Communities ◽  
Long Term Changes ◽  
Very High ◽  
Macrophyte Structure

ABSTRACT The Łęczna-Włodawa Plain, known also as the Łęczna-Wlodawa Lakeland, lies within the territory of the largest subregion of the Polesie region, covering over 1,300 km2. The main interest of the Łęczna-Włodawa Lakeland is that it is the oldest in the Central European Lowlands group of about 68 lakes. Among such a large number of lakes there exist all trophic types. However, since the late 1950’s, enormous dynamics of change associated with the disappearance of oligo- and mesotrophic lakes and their transformation into eutrophic, even hypertrophic, lakes have been observed. One of the biocenotic elements of the lakes, which are indicators of these changes, is aquatic plants. The aim of this study was to determine the macrophyte structure of Piaseczno Lake and changes of land use in its surroundings. Piaseczno Lake still represents very high natural values. A reduction in the number of macrophyte communities, which occurred especially in 2008, was a consequence of the fast-growing recreation infrastructure. From 1976 until 2010 an area of recreation infrastructure in the studied area increased more than 3.5 times, and in the built-up area more than five times, as well as a doubling of the total length of the roads. Meanwhile the surface area of wetlands and peatbogs significantly decreased - more than 11 times. Long-term changes in the structure of the macrophyte communities show that the number of communities has varied in each year, probably as a consequence of changes in landuse. Analysis showed changes to the surfaces inhabited by macrophytes, which have decreased significantly over only four years, by more than 25%. However, the proportion of rush communities has increased.

scholarly journals APASL HCV guidelines of virus-eradicated patients by DAA on how to monitor HCC occurrence and HBV reactivation

2019 ◽  
Vol 13 (6) ◽  
pp. 649-661 ◽  
Author(s):  
Tatsuo Kanda ◽  
George K. K. Lau ◽  
Lai Wei ◽  
Mitsuhiko Moriyama ◽  
Ming-Lung Yu ◽  
...  
Keyword(s):  
Hbv Dna ◽  
Hbv Reactivation ◽  
Close Attention ◽  
Short Term ◽  
Direct Acting Antiviral ◽  
B Virus ◽  
Direct Acting ◽  
Very High

Abstract In the direct-acting antiviral (DAA) era for hepatitis C virus (HCV) infection, sustained virological response (SVR) is very high, but close attention must be paid to the possible occurrence of hepatocellular carcinoma (HCC) and reactivation of hepatitis B virus (HBV) in patients with co-infection who achieved SVR in short term. HCC occurrence was more often observed in patients with previous HCC history. We found occurrence of HCC in 178 (29.6%) of 602 patients with previous HCC history (15.4 months mean follow-up post-DAA initiation) but, in contrast, in only 604 (1.3%) of 45,870 patients without previous HCC history (18.2 months mean follow-up). Thus, in these guidelines, we recommend the following: in patients with previous HCC history, surveillance at 4-month intervals for HCC by ultrasonography (US) and tumor markers should be performed. In patients without previous HCC history, surveillance at 6- to 12-month intervals for HCC including US is recommended until the long-term DAA treatment effects, especially for the resolution of liver fibrosis, are confirmed. This guideline also includes recommendations on how to follow-up patients who have been infected with both HCV and HBV. When HCV was eradicated in these HBsAg-positive patients or patients with previous HBV infection (anti-HBc and/or anti-HBs-positive), it was shown that HBV reactivation or HBV DNA reappearance was observed in 67 (41.4%) of 162 or 12 (0.9%) of 1317, respectively. For these co-infected patients, careful attention should be paid to HBV reactivation for 24 weeks post-treatment.

scholarly journals Capital Structure and Firms’ Performance: Evidence from Vietnam’s Stock Exchange

2015 ◽  
Vol 7 (12) ◽  
pp. 1 ◽  
Author(s):  
Tristan Nguyen ◽  
Huy-Cuong Nguyen
Keyword(s):  
Capital Structure ◽  
Stock Exchange ◽  
Debt Maturity ◽  
Management Process ◽  
Short Term ◽  
Fixed Assets ◽  
Two Factors ◽  
The Impact ◽  
Very High

<p>Our paper examines what impact capital structure has on firms’ performance in selected firms listed on HCMC Stock Exchange. The data is collected from 147 listed companies during the period from 2006 to 2014. The study not only checks the impact the level of leverage has on firms’ performance, which is found to be negative in this study, but it also uses the short-term and long-term debt ratios to see the effect of debt maturity. However, there is no difference whether it is short-term or long-term. Tangibility is found to be negative with a very high proportion on average. With the suggestion that companies might invest too much in fixed assets and there is a lack of efficiency, this could be the alert for firms to improve their management process. Size and growth are found to be positive, since larger firms have lower costs of bankruptcy and higher growth rates associate with higher performance. Moreover, the study also adds the effects of industry and macroeconomics, and the result shows a correlation between the two factors and firms’ performance.</p>

Lead concentrations in tissues of fruit bats (Pteropus sp.) in urban and non-urban locations

1993 ◽  
Vol 20 (3) ◽  
pp. 315 ◽  
Author(s):  
B Hariono ◽  
J Ng ◽  
RH Sutton
Keyword(s):  
Environmental Exposure ◽  
Urban Areas ◽  
Fruit Bats ◽  
Short Term ◽  
Probable Source ◽  
High Concentrations ◽  
Highly Correlated ◽  
High Lead ◽  
Very High

Lead concentrations were measured in tissues from 37 fruit bats from the Brisbane area and 5 bats from non-urban areas. On the basis of toxicity levels of 25 ug per g of kidney and 10 ug per g of liver, 11 of the Brisbane bats had concentrations consistent with toxicity. Other Brisbane bats had very high lead concentrations in bone and teeth. The lead concentrations in the non-urban bats were very low. Lead concentrations in the fur were variable but were highly correlated with concentrations in bones and teeth, reflecting long-term exposure to lead. High concentrations of lead were recovered from fur washings, which correlated very highly with the concentrations in kidney and liver, reflecting more recent and continuing exposure to lead. The source of the lead was not verified but the atmosphere was the probable source. Measurement of lead concentrations in the fur and its washings would appear to provide a means of monitoring lead accumulation in the tissues of fruit bats over both the long and short term. Such measurements could be valuable in monitoring environmental exposure to lead.

scholarly journals Estimating Long-Term Drinking Patterns for People with Lifetime Alcohol Use Disorder

2019 ◽  
Vol 39 (7) ◽  
pp. 765-780
Author(s):  
Carolina Barbosa ◽  
William N. Dowd ◽  
Arnie P. Aldridge ◽  
Christine Timko ◽  
Gary A. Zarkin
Keyword(s):  
High Risk ◽  
Alcohol Consumption ◽  
Alcohol Use ◽  
Transition Probabilities ◽  
World Health ◽  
Drinking Patterns ◽  
Short Term ◽  
Demographic Groups ◽  
Very High

Background. There is a lack of data on alcohol consumption over time. This study characterizes the long-term drinking patterns of people with lifetime alcohol use disorders who have engaged in treatment or informal care. Methods. We developed multinomial logit models using the National Epidemiologic Survey on Alcohol and Related Conditions (NESARC) to estimate short-term transition probabilities (TPs) among the 4 World Health Organization drinking risk levels (low, medium, high, and very high risk) and abstinence by age, sex, and race/ethnicity. We applied an optimization algorithm to convert 3-year TPs from NESARC to 1-year TPs, then used simulated annealing to calibrate TPs to a propensity-scored matched set of participants derived from a separate 16-year study of alcohol consumption. We validated the resulting long-term TPs using NESARC-III, a cross-sectional study conducted on a different cohort. Results. Across 24 demographic groups, the 1-year probability of remaining in the same state averaged 0.93, 0.81, 0.49, 0.51, and 0.63 for abstinent, low, medium, high, and very high-risk states, respectively. After calibration to the 16-year study data ( N = 420), resulting TPs produced state distributions that hit the calibration target. We find that the abstinent or low-risk states are very stable, and the annual probability of leaving the very high-risk state increases by about 20 percentage points beyond 8 years. Limitations. TPs for some demographic groups had small cell sizes. The data used to calibrate long-term TPs are based on a geographically narrow study. Conclusions. This study is the first to characterize long-term drinking patterns by combining short-term representative data with long-term data on drinking behaviors. Current research is using these patterns to estimate the long-term cost effectiveness of alcohol treatment.

Development, Survival and Reproduction of Camnula pellucida (Scudder) (Orthoptera: Acrididae) in Relation to Climatic Conditions

1966 ◽  
Vol 98 (2) ◽  
pp. 158-169 ◽  
Author(s):  
R. Pickford
Keyword(s):  
Decisive Role ◽  
Climatic Conditions ◽  
Reproductive Capacity ◽  
Short Term ◽  
Rate Of Development ◽  
Weather Patterns ◽  
Survival And Reproduction ◽  
Hot Weather ◽  
Very High

AbstractField-rearing studies of Camnula pellucida (Scudder) conducted at Saskatoon from 1960 to 1962 indicated that marked differences often occurred in rate of development, survival and fecundity because of differing weather patterns. Grasshoppers usually developed more rapidly as they hatched later in the season when temperatures were rising. In addition, striking differences occurred in growth rates of grasshoppers hatched on similar dates in different years due to sharply contrasting climatic conditions. Although survival of nymphs was generally high, mortality was consistently greatest during early nymphal life. Precipitation or excessively hot weather during this period increased mortality considerably, yet did not affect the older nymphs. Survival of adults was also generally high whether they fledged early or late in the season. They were able to endure very high temperatures during mid-summer or below freezing temperatures during late autumn. The three-year average reproductive capacity of this grasshopper was approximately eight egg-pods or 176 eggs per female. The rate of oviposition varied with temperature, reaching a maximum per female of approximately one pod every four days during mid-summer when temperatures were high and declining thereafter as temperatures dropped. The average egg-pod contained 22.13 eggs which showed a tendency to increase as adults fledged later in the season.It is suggested that climatic conditions frequently play a decisive role in the short-term modification of grasshopper infestations as well as in the long-term cyclic rise and fall in populations; consistently favourable or unfavourable conditions throughout the grasshopper cycle could result in an explosive outbreak or in almost complete elimination of any threat to the crop.

scholarly journals The successful use of fentanyl/fluanisone ('Hypnorm') as an anaesthetic for intracranial surgery in neonatal rats

2000 ◽  
Vol 34 (3) ◽  
pp. 260-264 ◽  
Author(s):  
Gavin J. Clowry ◽  
Paul A. Flecknell
Keyword(s):  
High Survival ◽  
High Survival Rate ◽  
Neonatal Rats ◽  
Short Term ◽  
Depth Of Anaesthesia ◽  
Fentanyl Citrate ◽  
Intracranial Surgery ◽  
Old Rats ◽  
Very High

This study reports on the successful use of fentanyl citrate and fluanisone ('Hypnorm') anaesthesia for intracranial surgery in neonatal (7-day-old) rats. Provided the anaesthetic was administered subcutaneously, the animals showed a very high survival rate in the short term (81/85, 95%) and showed no ill effects in the long term. The depth of anaesthesia was sufficient to allow the operation to be carried out without the animal reacting to any painful stimuli. However, the animals did make random movements during the period of surgical anaesthesia which were not related to any painful stimuli. Although these movements did not interfere with the surgery performed here, such movements would interfere with operations requiring greater precision, such as the localized micro-injection of neural tracers.

Between Catastrophes: God, Nature and Humanity

2021 ◽  
Vol 77 (2-3) ◽  
pp. 489-500
Author(s):  
John Milbank
Keyword(s):  
Human Life ◽  
Human Existence ◽  
The Other ◽  
Short Term ◽  
Global Consensus ◽  
First Response ◽  
Relative Stress ◽  
Doctrine Of Creation ◽  
The One

Critical responses to the pandemic have divided between the need to control and defeat it and fears of a new medicalisation of human existence. In the short-term the first response is right, but in the long-term the second. The ideological division on this issue on the left roughly correlates with a relative stress on the power of the market on the one hand or the power of the state on the other. But these are two halves of the same picture: the mechanisation of human life and the artificial rendering of the natural scarce and threatening. The tendencies that give rise to pandemics and those which exult in increasing total control are the same. Resistance can only come from a resistance to liberal mechanising as such. This requires the double sense that we are as spirits located within nature and yet as spirits transcend nature, which the theological doctrine of creation upholds. The challenge is to create a new global consensus and shared metaphysical politics around this legacy.

Sign in / Sign up

Export Citation Format

Share Document