271 research outputs found
The Principle of Minimum Differentiation Revisited: Return of the Median Voter
We study a linear location model (Hotelling, 1929) in which n (with n ≥ 2) boundedly rational players follow (noisy) myopic best-reply behavior. We show through numerical and mathematical analysis that such players spend almost all the time clustered together near the center, re-establishing Hotelling's “Principle of Minimum Differentiation” that had been discredited by equilibrium analyses. Thus, our analysis of the best-response dynamics shows that when considering e.g. market dynamics as well as their policy and welfare implications, it may be important to look beyond equilibrium analyse
Принцип "распространяемости" в современной новостной журналистике: критерии отбора событий
The article revised and updated the Galtung, J. & Ruge, M. system of twelve factors of ‘newsworthiness’ with consideration for the modern model of a two-way transaction, involving both news producer (the journalist) and the news receiver (the audience) in which spreadability became the core.Статья посвящена критериям отбора происшествий при составлении аудиторией своей собственной повестки дня и дает ответ на вопрос о том, какими признаками должно обладать происшествие, чтобы спровоцировать аудиторию распространять информацию о себе в социальных медиа. Приняв во внимание изменения медиапространства и новые исследования в области медиа, авторы сделали попытку скорректировать и дополнить критерии новостного отбора, предложенные Гантлунгом и Руге в 1965 г
Carrier concentrations in Bi_{2}Sr_{2-z}La_{z}CuO_{6+\delta} single crystals and their relation to Hall coefficient and thermopower
We measured the thermopower S and the Hall coefficients R_H of
Bi_{2}Sr_{2-z}La_{z}CuO_{6+\delta} (BSLCO) single crystals in a wide doping
range, in an effort to identify the actual hole concentrations per Cu, p, in
this system. It is found that the "universal" relation between the
room-temperature thermopower and T_c does not hold in the BSLCO system.
Instead, comparison of the temperature-dependent R_H data with other cuprate
systems is used as a tool to identify the actual p value. To justify this
approach, we compare normalized R_H(T) data of BSLCO, La_{2-x}Sr_{x}CuO_{4}
(LSCO), YBa_{2}Cu_{3}O_{y}, and Tl_{2}Ba_{2}CuO_{6+\delta}, and demonstrate
that the R_H(T) data of the LSCO system can be used as a template for the
estimation of p. The resulting phase diagram of p vs T_c for BSLCO suggests
that T_c is anomalously suppressed in the underdoped samples, becoming zero at
around p ~ 0.10, while the optimum T_c is achieved at p ~ 0.16 as expected.Comment: 4 pages including 5 figures, accepted for publication in Phys. Rev.
B, Rapid Communication
Zn-doping effect on the magnetotransport properties of Bi_{2}Sr_{2-x}La_{x}CuO_{6+\delta} single crystals
We report the magnetotransport properties of
Bi_{2}Sr_{2-x}La_{x}Cu_{1-z}Zn_{z}O_{6+\delta} (Zn-doped BSLCO) single crystals
with z of up to 2.2%. Besides the typical Zn-doping effects on the in-plane
resistivity and the Hall angle, we demonstrate that the nature of the
low-temperature normal state in the Zn-doped samples is significantly altered
from that in the pristine samples under high magnetic fields. In particular, we
observe nearly-isotropic negative magnetoresistance as well as an increase in
the Hall coefficient at very low temperatures in non-superconducting Zn-doped
samples, which we propose to be caused by the Kondo scattering from the local
moments induced by Zn impurities.Comment: 4 pages, 4 figures, final version (one reference added), published in
Phys. Rev.
On Effective Action of Multiple M5-branes and ABJM Action
We calculate the fluctuations from the classical multiple M5-brane solution
of ABJM action which we found in the previous paper. We obtain D4-brane-like
action but the gauge coupling constant depends on the spacetime coordinate.
This is consistent with the expected properties of M5-brane action, although we
will need to take into account the monopole operators in order to fully
understand M5-branes. We also see that the Nambu-Poisson bracket is hidden in
the solution.Comment: 21 pages; v2:version to appear in JHE
Massive Three-Dimensional Supergravity From R+R^2 Action in Six Dimensions
We obtain a three-parameter family of massive N=1 supergravities in three
dimensions from the 3-sphere reduction of an off-shell N=(1,0) six-dimensional
Poincare supergravity that includes a curvature squared invariant. The
three-dimensional theory contains an off-shell supergravity multiplet and an
on-shell scalar matter multiplet. We then generalise this in three dimensions
to an eight-parameter family of supergravities. We also find a duality
relationship between the six-dimensional theory and the N=(1,0) six-dimensional
theory obtained through a T^4 reduction of the heterotic string effective
action that includes the higher-order terms associated with the
supersymmetrisation of the anomaly-cancelling \tr(R\wedge R) term.Comment: Latex, 32 Pages, an equation is corrected, a few new equations and a
number of clarifying remarks are adde
Abelian-Higgs and Vortices from ABJM: towards a string realization of AdS/CMT
We present ans\"{a}tze that reduce the mass-deformed ABJM model to gauged
Abelian scalar theories, using the fuzzy sphere matrices . One such
reduction gives a Toda system, for which we find a new type of nonabelian
vortex. Another gives the standard Abelian-Higgs model, thereby allowing us to
embed all the usual (multi-)vortex solutions of the latter into the ABJM model.
By turning off the mass deformation at the level of the reduced model, we can
also continuously deform to the massive theory in the massless ABJM
case. In this way we can embed the Landau-Ginzburg model into the AdS/CFT
correspondence as a consistent truncation of ABJM. In this context, the mass
deformation parameter and a field VEV act as and
respectively, leading to a well-motivated AdS/CMT construction from string
theory. To further this particular point, we propose a simple model for the
condensed matter field theory that leads to an approximate description for the
ABJM abelianization. Finally, we also find some BPS solutions to the
mass-deformed ABJM model with a spacetime interpretation as an M2-brane ending
on a spherical M5-brane.Comment: 43 pages, latex, explanations added in the introduction, end of
section 4, and on page 2
Absolute calibration of imaging plate for GeV electrons
Copyright 2008 American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. The following article appeared in Review of Scientific Instruments, 79(6), 066102_1-066102_3, 2008 and may be found at http://dx.doi.org/10.1063/1.294021
Vortex loop operators, M2-branes and holography
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