2,289 research outputs found
Continuum discretized BCS approach for weakly bound nuclei
The Bardeen-Cooper-Schrieffer (BCS) formalism is extended by including the
single-particle continuum in order to analyse the evolution of pairing in an
isotopic chain from stability up to the drip line. We propose a continuum
discretized generalized BCS based on single-particle pseudostates (PS). These
PS are generated from the diagonalization of the single-particle Hamiltonian
within a Transformed Harmonic Oscillator (THO) basis. The consistency of the
results versus the size of the basis is studied. The method is applied to
neutron rich Oxygen and Carbon isotopes and compared with similar previous
works and available experimental data. We make use of the flexibility of the
proposed model in order to study the evolution of the occupation of the
low-energy continuum when the system becomes weakly bound. We find a larger
influence of the non-resonant continuum as long as the Fermi level approaches
zero.Comment: 20 pages, 16 figures, to be submitte
Diffusion of scientific credits and the ranking of scientists
Recently, the abundance of digital data enabled the implementation of graph
based ranking algorithms that provide system level analysis for ranking
publications and authors. Here we take advantage of the entire Physical Review
publication archive (1893-2006) to construct authors' networks where weighted
edges, as measured from opportunely normalized citation counts, define a proxy
for the mechanism of scientific credit transfer. On this network we define a
ranking method based on a diffusion algorithm that mimics the spreading of
scientific credits on the network. We compare the results obtained with our
algorithm with those obtained by local measures such as the citation count and
provide a statistical analysis of the assignment of major career awards in the
area of Physics. A web site where the algorithm is made available to perform
customized rank analysis can be found at the address
http://www.physauthorsrank.orgComment: Revised version. 11 pages, 10 figures, 1 table. The portal to compute
the rankings of scientists is at http://www.physauthorsrank.or
Implementation of the Quantum Fourier Transform
The quantum Fourier transform (QFT) has been implemented on a three bit
nuclear magnetic resonance (NMR) quantum computer, providing a first step
towards the realization of Shor's factoring and other quantum algorithms.
Implementation of the QFT is presented with fidelity measures, and state
tomography. Experimentally realizing the QFT is a clear demonstration of NMR's
ability to control quantum systems.Comment: 6 pages, 2 figure
An NMR Analog of the Quantum Disentanglement Eraser
We report the implementation of a three-spin quantum disentanglement eraser
on a liquid-state NMR quantum information processor. A key feature of this
experiment was its use of pulsed magnetic field gradients to mimic projective
measurements. This ability is an important step towards the development of an
experimentally controllable system which can simulate any quantum dynamics,
both coherent and decoherent.Comment: Four pages, one figure (RevTeX 2.1), to appear in Physics Review
Letter
20 years of network community detection
A fundamental technical challenge in the analysis of network data is the
automated discovery of communities - groups of nodes that are strongly
connected or that share similar features or roles. In this commentary we review
progress in the field over the last 20 years.Comment: 6 pages, 1 figure. Published in Nature Physic
The Supreme Court Perspective of Media Effects as Expressed in Campaign Finance Reform
The Bipartisan Campaign Reform Act (BCRA) of 2002 amended campaign finance law by banning unlimited soft money contributions to political parties and reforming the financing of advertising close to an election. In this ruling the Court is clearly concerned with the amount of money being donated to political candidates, which leads to the appearance of impropriety in gaining access to elected officials that in turn may influence legislation. In ruling on the constitutionality of this legislation, the Supreme Court also provided insight into its view of mass media effects. In applying the principles of cultivation theory and the media framing paradigm, the groups that can fund more commercials have an advantage with voters who may believe these repeated advertisements and vote for that particular candidate. This Article posits what might be the Supreme Court\u27s view of the media effects debate by examining its ruling in McConnell v. FEC
Photogrammetry for digital reconstruction of railway ballast particles – a cost-efficient method
Ballast aggregate is a natural material widely used in railway lines. Its mechanical properties and particle geometry are meticulously defined using well-established standards and characterisation procedures. Though extensively validated, these procedures have some limitations: they are operator dependent; only provide major particle dimensions; do not inform on surface colour; nor allow for advanced particle wear analysis or particle-based simulations. This work presents a cost-efficient photogrammetry method for 3D reconstruction of ballast particles, as an alternative to the significantly expensive laser scanning. It produces digital models of equivalent or higher quality, allowing for advanced and automated particle geometry analyses. Particle meshes produced here are shared among researchers.info:eu-repo/semantics/acceptedVersio
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