122 research outputs found
Atomic Compton profiles within different exchange-only theories
The Impulse Compton Profiles (CP's) J(q) and the - expectation values
for some inert gas atoms (He-Kr) are computed and compared within the
Harbola-Sahni (HS), Hartree-Fock(HF) theories and a Self Interaction Corrected
(SIC) density functional model. The Compton profiles for excited states of
Helium atom are also calculated. While the calculated CP's are found to
generally agree, they differ slightly from one another for small values of the
Compton parameter q and are in good agreement for large q values. The
expectation values within the three theories are also found to be comparable.
The HS formalism seem to mimic HF reasonably well in the momentum space,
establishing the logical consistency of the former.Comment: 15 page
Exactly solvable -symmetric models in two dimensions
Non-hermitian, -symmetric Hamiltonians, experimentally realized
in optical systems, accurately model the properties of open, bosonic systems
with balanced, spatially separated gain and loss. We present a family of
exactly solvable, two-dimensional, potentials for a
non-relativistic particle confined in a circular geometry. We show that the
symmetry threshold can be tuned by introducing a second
gain-loss potential or its hermitian counterpart. Our results explicitly
demonstrate that breaking in two dimensions has a rich phase
diagram, with multiple re-entrant symmetric phases.Comment: 6 pages, 6 figure
Momentum space properties from coordinate space electron density
Electron density and electron momentum density, while independently tractable
experimentally, bear no direct connection without going through the
many-electron wave function. However, invoking a variant of the
constrained-search formulation of density functional theory, we develop a
general scheme (valid for arbitrary external potentials) yielding decent
momentum space properties, starting exclusively from the coordinate space
electron density. Numerical illustration of the scheme is provided for the
closed-shell atomic systems He, Be and Ne and for singlet
electronic excited state for Helium by calculating the Compton profiles and the
expectation values derived from given coordinate space electron
densities.Comment: 4 pages, 1 figur
Nonexistence of local maxima in molecular electrostatic potential maps
It has been rigorously established by means of classical electrostatic arguments, that molecular electrostatic potential maps are devoid of local maxima. This forms a generalization of the earlier works of Politzer and co-workers which were restricted to the case of atoms
Spatiotemporal characteristics of atrial fibrillation electrograms: a novel marker for arrhythmia stability and termination
Background: Sequentially mapped complex fractionated atrial electrograms (CFAE) and dominant frequency (DF) sites have been targeted during catheter ablation for atrial fibrillation (AF). However, these strategies have yielded variable success and have not been shown to correlate consistently with AF dynamics. Here, we evaluated whether the spatiotemporal stability of CFAE and DF may be a better marker of AF sustenance and termination.
Methods: Eighteen sheep with 12 weeks of "one-kidney, one-clip" hypertension underwent open-chest studies. A total of 42 self-terminating (28–100 s) and 6 sustained (>15 min) AF episodes were mapped using a custom epicardial plaque and analyzed in 4-s epochs for CFAE, using the NavX CFE-m algorithm, and DF, using a Fast Fourier Transform. The spatiotemporal stability index (STSI) was calculated using the intraclass correlation coefficient of consecutive AF epochs.
Results: A total of 67,733 AF epochs were analyzed. During AF initiation, mean CFE-m and the STSI of CFE-m/DF were similar between sustained and self-terminating episodes, although median DF was higher in sustained AF (p=0.001). During sustained AF, the STSI of CFE-m increased significantly (p=0.02), whereas mean CFE-m (p=0.5), median DF (p=0.07), and the STSI of DF remained unchanged (p=0.5). Prior to AF termination, the STSI of CFE-m was significantly lower (p<0.001), with a physiologically non-significant decrease in median DF (−0.3 Hz, p=0.006) and no significant changes in mean CFE-m (p=0.14) or the STSI of DF (p=0.06).
Conclusions: Spatiotemporal stabilization of CFAE favors AF sustenance and its destabilization heralds AF termination. The STSI of CFE-m is more representative of AF dynamics than are the STSI of DF, sequential mean CFE-m, or median DF
Correlation of myocardial strain by CMR-feature tracking with substrate abnormalities detected by electro-anatomical mapping in patients with nonischemic cardiomyopathy
Characteristics of the phenotype of mixed cardiomyopathy in patients with implantable cardioverter-defibrillators
OnlinePublBackground or Purpose The prognosis of mixed cardiomyopathy (CMP) in patients with implanted cardioverter-defbrillators
(ICDs) has not been investigated. We aim to study the demographic, clinical, device therapies and survival characteristics
of mixed CMP in a cohort of patients implanted with a defbrillator.
Methods The term mixed CMP was used to categorise patients with impaired left ventricular ejection fraction attributed to
documented non-ischemic triggers with concomitant moderate coronary artery disease. This is a single center observational
cohort of 526 patients with a mean follow-up of 8.7±3.5 years.
Results There were 42.5% patients with ischemic cardiomyopathy (ICM), 26.9% with non-ischemic cardiomyopathy (NICM) and 30.6% with mixed CMP. Mixed CMP, compared to NICM, was associated with higher mean age
(69.1 ± 9.6 years), atrial fibrillation (55.3%) and greater incidence of comorbidities. The proportion of patients with
mixed CMP receiving device shocks was 23.6%, compared to 18.4% in NICM and 27% in ICM. The VT cycle length
recorded in mixed CMP (281.6 ± 43.1 ms) was comparable with ICM (282.5 ± 44 ms; p = 0.9) and lesser than NICM
(297.7±48.7 ms; p=0.1). All-cause mortality in mixed CMP (21.1%) was similar to ICM (20.1%; p=0.8) and higher
than NICM (15.6%; p = 0.2). The Kaplan–Meier curves revealed hazards of 1.57 (95% CI: 0.91, 2.68) for mixed CMP
compared to NICM.
Conclusion In a cohort of patients with ICD, the group with mixed CMP represents a phenotype predominantly comprised
of the elderly with a higher incidence of comorbidities. Mixed CMP resembles ICM in terms of number of device shocks
and VT cycle length. Trends of long-term prognosis of patients with mixed CMP are worse than NICM and similar to ICM.Deep Chandh Raja, Indira Samarawickrema, Sarat Krishna Menon, Rikvin Singh, Abhinav Mehta, Lukah Q. Tuan, Ulhas Pandurangi, Sanjiv Jain, David J. Callans, Francis E. Marchlinski, Walter P. Abhayaratna, Prashanthan Sanders, Rajeev K. Patha
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