1,557 research outputs found
Fidelity for imperfect postselection
We describe a simple measure of fidelity for mixed state postselecting
devices. The measure is most appropriate for postselection where the task
performed by the output is only effected by a specific state.Comment: 8 Pages, 8 Figure
Cardiac Magnetic Resonance T1 Mapping in Cardiomyopathies
Cardiac magnetic resonance (CMR) imaging has been widely used to assess myocardial perfusion and scar and is the noninvasive reference standard for identification of focal myocardial fibrosis. However, the late gadolinium enhancement (LGE) technique is limited in its accuracy for absolute quantification and assessment of diffuse myocardial fibrosis by technical and pathophysiological features. CMR relaxometry, incorporating T1 mapping, has emerged as an accurate, reproducible, highly sensitive, and quantitative technique for the assessment of diffuse myocardial fibrosis in a number of disease states. We comprehensively review the physics behind CMR relaxometry, the evidence base, and the clinical applications of this emerging technique
Alfv\`en wave phase-mixing and damping in the ion cyclotron range of frequencies
Aims. To determine the effect of the Hall term in the generalised Ohm's law
on the damping and phase mixing of Alfven waves in the ion cyclotron range of
frequencies in uniform and non-uniform equilibrium plasmas. Methods. Wave
damping in a uniform plasma is treated analytically, whilst a Lagrangian remap
code (Lare2d) is used to study Hall effects on damping and phase mixing in the
presence of an equilibrium density gradient. Results. The magnetic energy
associated with an initially Gaussian field perturbation in a uniform resistive
plasma is shown to decay algebraically at a rate that is unaffected by the Hall
term to leading order in k^2di^2 where k is wavenumber and di is ion skin
depth. A similar algebraic decay law applies to whistler perturbations in the
limit k^2di^2>>1. In a non-uniform plasma it is found that the
spatially-integrated damping rate due to phase mixing is lower in Hall MHD than
it is in MHD, but the reduction in the damping rate, which can be attributed to
the effects of wave dispersion, tends to zero in both the weak and strong phase
mixing limits
Hydrogen bonding in infinite hydrogen fluoride and hydrogen chloride chains
Hydrogen bonding in infinite HF and HCl bent (zigzag) chains is studied using
the ab initio coupled-cluster singles and doubles (CCSD) correlation method.
The correlation contribution to the binding energy is decomposed in terms of
nonadditive many-body interactions between the monomers in the chains, the
so-called energy increments. Van der Waals constants for the two-body
dispersion interaction between distant monomers in the infinite chains are
extracted from this decomposition. They allow a partitioning of the correlation
contribution to the binding energy into short- and long-range terms. This
finding affords a significant reduction in the computational effort of ab
initio calculations for solids as only the short-range part requires a
sophisticated treatment whereas the long-range part can be summed immediately
to infinite distances.Comment: 9 pages, 4 figures, 3 tables, RevTeX4, corrected typo
Soliton bound states in semiconductor disk laser
We report what we believe is the first demonstration of a temporal soliton bound state in semiconductor disk laser. The laser was passively mode-locked using a quantum dot based semiconductor saturable absorber mirror (QD-SESAM). Two mode-locking regimes were observed where the laser would emit single or closely spaced double pulses (soliton bound state regime) per cavity round-trip. The pulses in soliton bound state regime were spaced by discrete, fixed time duration. We use a system of delay differential equations to model the dynamics of our device
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