52,761 research outputs found
Some Further Economics of Easter Island: Adding Subsistence and Resource Conservation
We extend Brander-Taylor's model of development on Easter Island by adding a resource subsistence requirement to people's preferences, and a conservation incentive in the form of a revenue-neutral, ad valorem tax on resource consumption. Adding subsistence improves plausibility; makes overshoot and collapse of population more extreme, and the steady state less stable; and allows for the possibility that statue building and erection will suddenly stop, in line with the archaeological evidence. We find a tax rate path which almost completely prevents overshoot, and conjecture that the overall strength of this path must rise when the subsistence level rises.
Integer Factorization with a Neuromorphic Sieve
The bound to factor large integers is dominated by the computational effort
to discover numbers that are smooth, typically performed by sieving a
polynomial sequence. On a von Neumann architecture, sieving has log-log
amortized time complexity to check each value for smoothness. This work
presents a neuromorphic sieve that achieves a constant time check for
smoothness by exploiting two characteristic properties of neuromorphic
architectures: constant time synaptic integration and massively parallel
computation. The approach is validated by modifying msieve, one of the fastest
publicly available integer factorization implementations, to use the IBM
Neurosynaptic System (NS1e) as a coprocessor for the sieving stage.Comment: Fixed typos in equation for modular roots (Section II, par. 6;
Section III, par. 2) and phase calculation (Section IV, par 2
B-Physics at the Tevatron (Proceedings of PASCOS2010)
We report on recent B-Physics results from the Tevatron. The topics covered
include measurement of the polarization amplitudes in ,
the search for rare flavor-changing neutral-current decays, CP violation in
and semileptonic decays, and a new measurement
of the like-sign asymmetry in dimuon events.Comment: 6 pages, proceedings paper, 16th International Symposium on
Particles, Strings, and Cosmology, Valencia, Spain, July 19 - 23, 201
Earthquake cycles and neural reverberations
Driven systems of interconnected blocks with stick-slip friction capture main features of earthquake processes. The microscopic dynamics closely resemble those of spiking nerve cells. We analyze the differences in the collective behavior and introduce a class of solvable models. We prove that the models exhibit rapid phase locking, a phenomenon of particular interest to both geophysics and neurobiology. We study the dependence upon initial conditions and system parameters, and discuss implications for earthquake modeling and neural computation
Entropy in quantum chromodynamics
We review the role of zero-temperature entropy in several closely-related
contexts in QCD. The first is entropy associated with disordered condensates,
including . The second is vacuum entropy arising from QCD
solitons such as center vortices, yielding confinement and chiral symmetry
breaking. The third is entanglement entropy, which is entropy associated with a
pure state, such as the QCD vacuum, when the state is partially unobserved and
unknown. Typically, entanglement entropy of an unobserved three-volume scales
not with the volume but with the area of its bounding surface. The fourth
manifestation of entropy in QCD is the configurational entropy of
light-particle world-lines and flux tubes; we argue that this entropy is
critical for understanding how confinement produces chiral symmetry breakdown,
as manifested by a dynamically-massive quark, a massless pion, and a condensate.Comment: 22 pages, 2 figures. Preprint version of invited review for Modern
Physics Letters
Bayesian model-independent evaluation of expansion rates of the universe
Marginal likelihoods for the cosmic expansion rates are evaluated using the
`Constitution' data of 397 supernovas, thereby updating the results in some
previous works. Even when beginning with a very strong prior probability that
favors an accelerated expansion, we obtain a marginal likelihood for the
deceleration parameter peaked around zero in the spatially flat case. It
is also found that the new data significantly constrains the cosmographic
expansion rates, when compared to the previous analyses. These results may
strongly depend on the Gaussian prior probability distribution chosen for the
Hubble parameter represented by , with . This and similar
priors for other expansion rates were deduced from previous data. Here again we
perform the Bayesian model-independent analysis in which the scale factor is
expanded into a Taylor series in time about the present epoch. Unlike such
Taylor expansions in terms of redshift, this approach has no convergence
problem.Comment: To appear in Astrophysics and Space Scienc
Fractals and Scars on a Compact Octagon
A finite universe naturally supports chaotic classical motion. An ordered
fractal emerges from the chaotic dynamics which we characterize in full for a
compact 2-dimensional octagon. In the classical to quantum transition, the
underlying fractal can persist in the form of scars, ridges of enhanced
amplitude in the semiclassical wave function. Although the scarring is weak on
the octagon, we suggest possible subtle implications of fractals and scars in a
finite universe.Comment: 6 pages, 3 figs, LaTeX fil
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