15,075 research outputs found
Hadron Correlation in Jets
We review some recent experimental and theoretical work on the correlation
among hadrons produced at intermediate at RHIC. The topics include:
forward and backward asymmetry with and without trigger at mid-rapidity,
associated-particle distribution on the near side, the puzzle and its
solution, associated particles on the away side, and two-jet recombination at
LHC.Comment: Talk given at the 11th Workshop on Correlation and Fluctuation in
Multiparticle Production, Hangzhou, China, Nov 21-24, 200
Density scaling in viscous liquids: From relaxation times to four-point susceptibilities
We present numerical calculations of a four-point dynamic susceptibility,
chi_4(t), for the Kob-Andersen Lennard-Jones mixture as a function of
temperature T and density rho. Over a relevant range of T and rho, the full
t-dependence of chi_4(t) and thus the maximum in chi_4(t), which is
proportional to the dynamic correlation volume, are invariant for state points
for which the scaling variable rho^gamma/T is constant. The value of the
material constant gamma is the same as that which superposes the relaxation
time, tau, of the system versus rho^gamma/T. Thus, the dynamic correlation
volume is directly related to tau for any thermodynamic condition in the regime
where density scaling holds. Finally, we examine the conditions under which the
density scaling properties are related to the existence of strong correlations
between pressure and energy fluctuations.Comment: 5 pages, 4 figures, updated reference
Affirmative Action and Its Mythology
For more than three decades, critics and supporters of affirmative action have fought for the moral high ground  through ballot initiatives and lawsuits, in state legislatures, and in varied courts of public opinion. The goal of this paper is to show the clarifying power of economic reasoning to dispel some myths and misconceptions in the racial affirmative action debates. We enumerate seven commonly held (but mistaken) views one often encounters in the folklore about affirmative action (affirmative action may involve goals and timelines, but definitely not quotas, e.g.). Simple economic arguments reveal these seven views to be more myth than fact.
Electron-Phonon Interaction in Embedded Semiconductor Nanostructures
The modification of acoustic phonons in semiconductor nanostructures embedded
in a host crystal is investigated including corrections due to strain within
continuum elasticity theory. Effective elastic constants are calculated
employing {\em ab initio} density functional theory. For a spherical InAs
quantum dot embedded in GaAs barrier material, the electron-phonon coupling is
calculated. Its strength is shown to be suppressed compared to the assumption
of bulk phonons
Counterion density profiles at charged flexible membranes
Counterion distributions at charged soft membranes are studied using
perturbative analytical and simulation methods in both weak coupling
(mean-field or Poisson-Boltzmann) and strong coupling limits. The softer the
membrane, the more smeared out the counterion density profile becomes and
counterions pentrate through the mean-membrane surface location, in agreement
with anomalous scattering results. Membrane-charge repulsion leads to a
short-scale roughening of the membrane.Comment: 4 pages, 4 figure
Understanding ratio distribution in the mixed events
The event mixing method is analyzed for the study of the event-by-event
ratio distribution. It is shown that there exists some correlation
between the kaon and pion multiplicities in the mixed events. The ratio
distributions in the mixed events for different sets of real events are shown.
The dependence of the distributions on the mean ratio, mean and
variance of multiplicity distribution in the real events is investigated
systematically. The effect of imperfect particle identification on the
ratio distribution in the mixed event is also considered.Comment: 11 pages in revtex, 8 eps figures include
The SNR G106.3+2.7 and its Pulsar Wind Nebula: relics of triggered star formation in a complex environment
We propose that the pulsar nebula associated with the pulsar J2229+6114 and
the supernova remnant (SNR) G106.3+2.7 are the result of the same supernova
explosion. The whole structure is located at the edge of an HI bubble with
extended regions of molecular gas inside. The radial velocities of both the
atomic hydrogen and the molecular material suggest a distance of 800 pc. At
this distance the SNR is 14 pc long and 6 pc wide. Apparently the bubble was
created by the stellar wind and supernova explosions of a group of stars in its
center which also triggered the formation of the progenitor star of G106.3+2.7.
The progenitor star exploded at or close to the current position of the pulsar,
which is at one end of the SNR rather than at its center. The expanding shock
wave of the supernova explosion created a comet shaped supernova remnant by
running into dense material and then breaking out into the inner part of the HI
bubble. A synchrotron nebula with a shell-like structure (the ``Boomerang'') of
length 0.8 pc was created by the pulsar wind interacting with the dense ambient
medium. The expanding shock wave created an HI shell of mass 0.4 Msun around
this nebula by ionizing the atomic hydrogen in its vicinity.Comment: 10 pages, Latex, with aastex and emulateapj5, 5 figures. ApJ,
accepted, scheduled for the v560 n1 p1 Oct 10, 2001 issu
Coordinating reforms in transition economies
We establish a theory to analyze how initial conditions of organizational differences in transition economies affect reform strategies, especially the 'big-bang' approach in Eastern Europe and former Soviet Union economies as the U-form and the 'experimental' approach in China as the M-form. We model the coordination of specialized tasks inside an organization as 'attribute matching' and compare organizational forms (U-form and M-form) in coordinating reforms. Organizational forms affect the information structure of an organization and thus the way to coordinate reforms. Compared to the U-form, the M-form organization achieves better coordination but suffers from higher costs due to a lack of scale economies. The M-form has a distinctive advantage in carrying out experimentation that it is more flexible in reforms.postprin
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