52 research outputs found
Three flavors of extremal Betti tables
We discuss extremal Betti tables of resolutions in three different contexts.
We begin over the graded polynomial ring, where extremal Betti tables
correspond to pure resolutions. We then contrast this behavior with that of
extremal Betti tables over regular local rings and over a bigraded ring.Comment: 20 page
Improved Holographic QCD
We provide a review to holographic models based on Einstein-dilaton gravity
with a potential in 5 dimensions. Such theories, for a judicious choice of
potential are very close to the physics of large-N YM theory both at zero and
finite temperature. The zero temperature glueball spectra as well as their
finite temperature thermodynamic functions compare well with lattice data. The
model can be used to calculate transport coefficients, like bulk viscosity, the
drag force and jet quenching parameters, relevant for the physics of the
Quark-Gluon Plasma.Comment: LatEX, 65 pages, 28 figures, 9 Tables. Based on lectures given at
several Schools. To appear in the proceedinds of the 5th Aegean School
(Milos, Greece
How to Argue about Health Care
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/68919/2/10.1177_107755878704400102.pd
A Tail of a Quark in N=4 SYM
We study the dynamics of a `composite' or `dressed' quark in strongly-coupled
large-N_c N=4 super-Yang-Mills, making use of the AdS/CFT correspondence. We
show that the standard string dynamics nicely captures the physics of the quark
and its surrounding non-Abelian field configuration, making it possible to
derive a relativistic equation of motion that incorporates the effects of
radiation damping. From this equation one can deduce a non-standard dispersion
relation for the composite quark, as well as a Lorentz covariant formula for
its rate of radiation. We explore the consequences of the equation in a few
simple examples.Comment: 26 pages, no figures. v2: added brief clarification on string
boundary conditions, version to be published in JHE
Regular rates of popular culture change reflect random copying
Almost by definition, âpopular cultureâ reflects the effects of most people imitating those around them. At the same time, trends and fashions are constantly changing, with future outcomes potentially irrational and nearly impossible to predict. A simple null model, which captures these seemingly conflicting tendencies of conformity and change, involves the random copying of cultural variants between individuals, with occasional innovation. Here, we show that the random-copying model predicts a continual flux of initially obscure new ideas (analogous to mutations) becoming highly popular by chance alone, such that the turnover rate on a list of most popular variants depends on the list size and the amount of innovation but not on population size. We also present evidence for remarkably regular turnover on âpop chartsââincluding the most popular music, first names, and dog breeds in 20th-century United Statesâwhich fits this expectation. By predicting parametric effects on the turnover of popular fashion, the random-copying model provides an additional means of characterizing collective copying behavior in culture evolution
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