2,856 research outputs found

    Fission modes of 256Fm and 258Fm in a microscopic approach

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    A static microscopic study of potential-energy surfaces within the Skyrme-Hartree-Fock-plus-BCS model is carried out for the 256Fm and 258Fm isotopes with the goal of deducing some properties of spontaneous fission. The calculated fission modes are found to be in agreement with the experimentaly observed asymmetric-to-symmetric transition in the fragment-mass distributions and with the high- and low-total-kinetic-energy modes experimentally observed in 258Fm. Most of the results are similar to those obtained in macroscopic-microscopic models as well as in recent Hartree-Fock-Bogolyubov calculations with the Gogny interaction, with a few differences in their interpretations. In particular an alternative explanation is proposed for the low-energy fission mode of 258Fm.Comment: 14 pages, 11 figures, 3 tables, submitted to Phys. Rev.

    Alien Registration- Bonneau, Armand M. (Lewiston, Androscoggin County)

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    https://digitalmaine.com/alien_docs/30599/thumbnail.jp

    Alien Registration- Bonneau, Armand M. (Lewiston, Androscoggin County)

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    https://digitalmaine.com/alien_docs/30599/thumbnail.jp

    Constrained Cost-Coupled Stochastic Games with Independent State Processes

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    We consider a non-cooperative constrained stochastic games with N players with the following special structure. With each player there is an associated controlled Markov chain. The transition probabilities of the i-th Markov chain depend only on the state and actions of controller i. The information structure that we consider is such that each player knows the state of its own MDP and its own actions. It does not know the states of, and the actions taken by other players. Finally, each player wishes to minimize a time-average cost function, and has constraints over other time-avrage cost functions. Both the cost that is minimized as well as those defining the constraints depend on the state and actions of all players. We study in this paper the existence of a Nash equilirium. Examples in power control in wireless communications are given.Comment: 7 pages, submitted in september 2006 to Operations Research Letter

    GOTCHA Password Hackers!

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    We introduce GOTCHAs (Generating panOptic Turing Tests to Tell Computers and Humans Apart) as a way of preventing automated offline dictionary attacks against user selected passwords. A GOTCHA is a randomized puzzle generation protocol, which involves interaction between a computer and a human. Informally, a GOTCHA should satisfy two key properties: (1) The puzzles are easy for the human to solve. (2) The puzzles are hard for a computer to solve even if it has the random bits used by the computer to generate the final puzzle --- unlike a CAPTCHA. Our main theorem demonstrates that GOTCHAs can be used to mitigate the threat of offline dictionary attacks against passwords by ensuring that a password cracker must receive constant feedback from a human being while mounting an attack. Finally, we provide a candidate construction of GOTCHAs based on Inkblot images. Our construction relies on the usability assumption that users can recognize the phrases that they originally used to describe each Inkblot image --- a much weaker usability assumption than previous password systems based on Inkblots which required users to recall their phrase exactly. We conduct a user study to evaluate the usability of our GOTCHA construction. We also generate a GOTCHA challenge where we encourage artificial intelligence and security researchers to try to crack several passwords protected with our scheme.Comment: 2013 ACM Workshop on Artificial Intelligence and Security (AISec

    Nonpartisan election formats do not affect voting behaviors

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    Nonpartisan elections—in which candidates are not endorsed by a political party and their party affiliation does not appear on the ballot—have been criticized as depriving crucial information to voters, making it difficult for them to vote for candidates that represent their beliefs. Chris W. Bonneau and Damon M. Cann tested the impact of nonpartisan election conditions using both a laboratory experiment and data from the Cooperative Congressional Election Survey. They find that there is no significant difference between voting behaviors in partisan and nonpartisan election formats

    Sleepiness and fatigue following traumatic brain injury

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    Objectives : To compare individuals with traumatic brain injury (TBI) to healthy controls (CTLs) on measures of sleepiness, fatigue, and sleep, and explore correlates of sleepiness and fatigue separately for each group. Methods : Participants were 22 adults with moderate/severe TBI (time since injury ⩾1 year; mean = 53.0 ± 37.1 months) and 22 matched healthy CTLs. They underwent one night of polysomnographic (PSG) recording of their sleep followed the next day by the Maintenance of Wakefulness Test (MWT). They also completed a 14-day sleep diary, the Epworth Sleepiness Scale (ESS), the Functional Outcomes of Sleep Questionnaire (FOSQ), and the Multidimensional Fatigue Inventory (MFI). Results : There were no significant group differences on measures of objective (MWT) or subjective (ESS) sleepiness, both groups being quite alert. However, TBI participants reported greater consequences of sleepiness on their general productivity (FOSQ), spent more time in bed at night, and napped more frequently and for a longer time during the day. Subjective fatigue was significantly higher in TBI participants on the general, physical, and mental fatigue MFI subscales. There were no between-group differences on any sleep parameters derived either from PSG or sleep diary. Conclusions : Fatigue appeared to be a more prominent symptom than sleepiness when assessed between 1 and 11 years after TBI. Participants with TBI used compensatory strategies such as increasing time spent in bed and daytime napping in this sample. Future research should document the time course of sleepiness and fatigue after TBI and investigate treatment options
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