3,831 research outputs found
Generalized parton distributions of nuclei
We review recent theoretical results on generalized parton distributions
(GPDs) of nuclei, emphasizing the following three roles of nuclear GPDs: (i)
complementarity to free proton GPDs, (ii) the enhancement of traditional
nuclear effects such as nuclear binding, EMC effect, nuclear shadowing, and
(iii) an access to novel nuclear effects such as medium modifications of bound
nucleons.Comment: 5 pages, 2 figures. Revised version contains additional references.
Presented at CIPANP 2009: 10th Conference on the Intersections of Particle
and Nuclear Physics, La Jolla, California, May 26-31, 200
The Electron-Ion Collider
The future Electron-Ion Collider (EIC) is a proposed new facility to collide
high-energy electrons with beams of polarized protons/light nuclei and
unpolarized nuclei. We overview the goals of the project and key measurements
at the EIC. We also briefly comment on recent developments of the project.Comment: 4 pages, 1 figure. Presented at CIPANP 2009: 10th Conference on the
Intersections of Particle and Nuclear Physics, La Jolla, California, May
26-31, 200
Managing urban socio-technical change? Comparing energy technology controversies in three European contexts
A {\em local graph partitioning algorithm} finds a set of vertices with small
conductance (i.e. a sparse cut) by adaptively exploring part of a large graph
, starting from a specified vertex. For the algorithm to be local, its
complexity must be bounded in terms of the size of the set that it outputs,
with at most a weak dependence on the number of vertices in . Previous
local partitioning algorithms find sparse cuts using random walks and
personalized PageRank. In this paper, we introduce a randomized local
partitioning algorithm that finds a sparse cut by simulating the {\em
volume-biased evolving set process}, which is a Markov chain on sets of
vertices. We prove that for any set of vertices that has conductance at
most , for at least half of the starting vertices in our algorithm
will output (with probability at least half), a set of conductance
. We prove that for a given run of the algorithm,
the expected ratio between its computational complexity and the volume of the
set that it outputs is . In comparison, the best
previous local partitioning algorithm, due to Andersen, Chung, and Lang, has
the same approximation guarantee, but a larger ratio of between the complexity and output volume. Using our local
partitioning algorithm as a subroutine, we construct a fast algorithm for
finding balanced cuts. Given a fixed value of , the resulting algorithm
has complexity and returns a cut with
conductance and volume at least ,
where is the largest volume of any set with conductance at most
.Comment: 20 pages, no figure
On the nature of bias and defects in the software specification process
Implementation bias in a specification is an arbitrary constraint in the solution space. This paper describes the problem of bias. Additionally, this paper presents a model of the specification and design processes describing individual subprocesses in terms of precision/detail diagrams and a model of bias in multi-attribute software specifications. While studying how bias is introduced into a specification we realized that software defects and bias are dual problems of a single phenomenon. This was used to explain the large proportion of faults found during the coding phase at the Software Engineering Laboratory at NASA/GSFC
p6 - Chiral Resonating Valence Bonds in the Kagome Antiferromagnet
The Kagome Heisenberg antiferromagnet is mapped onto an effective Hamiltonian
on the star superlattice by Contractor Renormalization. Comparison of ground
state energies on large lattices to Density Matrix Renormalization Group
justifies truncation of effective interactions at range 3. Within our accuracy,
magnetic and translational symmetries are not broken (i.e. a spin liquid ground
state). However, we discover doublet spectral degeneracies which signal the
onset of p6 - chirality symmetry breaking. This is understood by simple mean
field analysis. Experimentally, the p6 chiral order parameter should split the
optical phonons degeneracy near the zone center. Addition of weak next to
nearest neighbor coupling is discussed.Comment: 7 pages, 5 figures including supplementary materia
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