44,880 research outputs found
Clustering and Micro-immiscibility in Alcohol-Water Mixtures: Evidence from Molecular Dynamics Simulations
We have investigated the hydrogen-bonded structures in liquid methanol and a
7:3 mole fraction aqueous solution using classical Molecular Dynamics
simulations at 298K and ambient pressure. We find that, in contrast to recent
predictions from X-ray emission studies, the hydrogen-bonded structure in
liquid methanol is dominated by chain and small ring structures. In the
methanol-rich solution, we find evidence of micro-immiscibility, supporting
recent conclusions derived from neutron diffraction data.Comment: 5 pages, 4 figure
The quantum correlation between the selection of the problem and that of the solution sheds light on the mechanism of the quantum speed up
In classical problem solving, there is of course correlation between the
selection of the problem on the part of Bob (the problem setter) and that of
the solution on the part of Alice (the problem solver). In quantum problem
solving, this correlation becomes quantum. This means that Alice contributes to
selecting 50% of the information that specifies the problem. As the solution is
a function of the problem, this gives to Alice advanced knowledge of 50% of the
information that specifies the solution. Both the quadratic and exponential
speed ups are explained by the fact that quantum algorithms start from this
advanced knowledge.Comment: Earlier version submitted to QIP 2011. Further clarified section 1,
"Outline of the argument", submitted to Phys Rev A, 16 page
Assessing the quality of a student-generated question repository
We present results from a study that categorizes and assesses the quality of
questions and explanations authored by students, in question repositories
produced as part of the summative assessment in introductory physics courses
over the past two years. Mapping question quality onto the levels in the
cognitive domain of Bloom's taxonomy, we find that students produce questions
of high quality. More than three-quarters of questions fall into categories
beyond simple recall, in contrast to similar studies of student-authored
content in different subject domains. Similarly, the quality of
student-authored explanations for questions was also high, with approximately
60% of all explanations classified as being of high or outstanding quality.
Overall, 75% of questions met combined quality criteria, which we hypothesize
is due in part to the in-class scaffolding activities that we provided for
students ahead of requiring them to author questions.Comment: 24 pages, 5 figure
Size-Change Abstraction and Max-Plus Automata
Max-plus automata (over ℕ ∪ − ∞) are finite devices that map input words to non-negative integers or − ∞. In this paper we present (a) an algorithm allowing to compute the asymptotic behaviour of max-plus automata, and (b) an application of this technique to the evaluation of the computational time complexity of programs
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Today's problems with the evaluation methods of full lightning impulse parameters as described in IEC 60060-1
In this paper the present problems with the evaluation methods for lightning impulse parameters, as defined in IEC 60060-1, are described. Also the current practice of evaluation in many laboratories world-wide, that is obtained by a questionnaire, is presented. Some of the work performed up the present time and the initial conclusions are reported, then some recommendations are made for future work
The Logit Equilibrium: A Perspective on Intuitive Behavioral Anomalies
This paper considers a class of models in which rank-based payoffs are sensitive to small amounts of noise in decision making. Examples include auction, price-competition, coordination, and location games. Observed laboratory behavior in these games is often responsive to asymmetric costs associated with deviations from the Nash equilibrium. These payoff asymmetry effects are incorporated in an approach that introduces noisy behavior via probabilistic choice. In equilibrium, behavior is characterized by a probability distribution that satisfies a "rational expectations" consistency condition: the beliefs that determine player's expected payoffs match the decision distributions that arise from applying a logit probabilistic choice function to those expected payoffs. We prove existence of a unique, symmetric logit (quantal response) equilibrium and derive comparative statics results. The paper provides a unified perspective on many recent laboratory studies of games in which Nash equilibrium predictions are inconsistent with both intuition and experimental evidence.logit equilibrium, quantal response equilibrium, probabilistic choice, auctions.
Stochastic Game Theory: Adjustment to Equilibrium Under Noisy Directional Learning
This paper presents a dynamic model in which agents adjust their decisions in the direction of higher payoffs, subject to random error. This process produces a probability distribution of players' decisions whose evolution over time is determined by the Fokker-Planck equation. The dynamic process is stable for all potential games, a class of payoff structures that includes several widely studied games. In equilibrium, the distributions that determine expected payoffs correspond to the distributions that arise from the logit function applied to those expected payoffs. This "logit equilibrium" forms a stochastic generalization of the Nash equilibrium and provides a possible explanation of anomalous laboratory data.bounded rationality, noisy directional learning, Fokker- Planck equation, potential games, logit equilibrium, stochastic potential.
Superfluid Motion of Light
Superfluidity, the ability of a fluid to move without dissipation, is one of
the most spectacular manifestations of the quantum nature of matter. We explore
here the possibility of superfluid motion of light. Controlling the speed of a
light packet with respect to a defect, we demonstrate the presence of
superfluidity and, above a critical velocity, its breakdown through the onset
of a dissipative phase. We describe a possible experimental realization based
on the transverse motion through an array of waveguides. These results open new
perspectives in transport optimization.Comment: 4 pages, 3 figure
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