Using a spectrally resolved electron interferometry technique, we measure photoionization time delays between the 3s and 3p subshells of argon over a large 34-eV energy range covering the Cooper ...minima in both subshells. The observed strong variations of the 3s − 3p delay difference, including a sign change, are well reproduced by theoretical calculations using the two-photon two-color random-phase approximation with exchange. Strong shake-up channels lead to photoelectrons spectrally overlapping with those emitted from the 3s subshell. These channels need to be included in our analysis to reproduce the experimental data. Our measurements provide a benchmark for multielectronic theoretical models aiming at an accurate description of interchannel correlation.
Synopsis Photoionization time delays between the 3s and 3p subshells of argon have been measured over a large energy range (35-70eV) covering the Cooper minima in both subshells, providing stringent ...tests for interchannel correlation theories.
Quantum coherence plays a fundamental role in the study and control of ultrafast dynamics in matter. In the case of photoionization, entanglement of the photoelectron with the ion is a well-known ...source of decoherence when only one of the particles is measured. Here, we investigate decoherence due to entanglement of the radial and angular degrees of freedom of the photoelectron. We study two-photon ionization via the 2s2p autoionizing state in He using high spectral resolution photoelectron interferometry. Combining experiment and theory, we show that the strong dipole coupling of the 2s2p and 2p
2
states results in the entanglement of the angular and radial degrees of freedom. This translates, in angle-integrated measurements, into a dynamic loss of coherence during autoionization.
Graphic Abstract
Using a spectrally resolved electron interferometry technique, we measure photoionization time delays between the \(3s\) and \(3p\) subshells of argon over a large 34-eV energy range covering the ...Cooper minima in both subshells. The observed strong variations of the \(3s-3p\) delay difference, including a sign change, are well reproduced by theoretical calculations using the Two-Photon Two-Color Random Phase Approximation with Exchange. Strong shake-up channels lead to photoelectrons spectrally overlapping with those emitted from the \(3s\) subshell. These channels need to be included in our analysis to reproduce the experimental data. Our measurements provide a stringent test for multielectronic theoretical models aiming at an accurate description of inter-channel correlation.
Autoionization, which results from the interference between direct photoionization and photoexcitation to a discrete state decaying to the continuum by configuration interaction, is a well known ...example of the important role of electron correlation in light-matter interaction. Information on this process can be obtained by studying the spectral, or equivalently, temporal complex amplitude of the ionized electron wavepacket. Using an energy-resolved interferometric technique, we measure the spectral amplitude and phase of autoionized wavepackets emitted via the sp2+ and sp3+ resonances in helium. These measurements allow us to reconstruct the corresponding temporal profiles by Fourier transform. In addition, applying various time-frequency representations, we observe the build up of the wavepackets in the continuum, monitor the instantaneous frequencies emitted at any time and disentangle the dynamics of the direct and resonant ionization channels.
The motion of the carotid artery wall can quantitatively be estimated from sequences of B-mode ultrasound images. In this paper, the effects of dynamic range (DR) and persistence, along with that of ...image normalization, were studied, in an attempt to suggest optimal values for reliable motion analysis. Image sequences were recorded using four different values for DR, i.e., 0, 48, 66, and 90 dB, and three different values for persistence, i.e., 0, 5.6, and 50. Radial and axial displacements, as well as the correlation coefficients (CCs), were estimated using block matching from recordings with durations of about 3 s. The variances of radial and axial displacements were not significantly affected by changes in DR and persistence. The mean value of the CC, which is an index of the reliability of motion analysis, was also not significantly affected by these settings. However, an increase in persistence increased the delays between peak radial displacements and cardiac systole. Image normalization did not affect the results of motion analysis. It is suggested that high values of DR (66 or 90 dB) and low values of persistence (0 or 5.6) are used for motion analysis based on block matching.
Abstract The goal of this paper is to examine the classification capabilities of various prediction and approximation methods and suggest which are most likely to be suitable for the clinical ...setting. Various prediction and approximation methods are applied in order to detect and extract those which provide the better differentiation between control and patient data, as well as members of different age groups. The prediction methods are local linear prediction, local exponential prediction, the delay times method, autoregressive prediction and neural networks. Approximation is computed with local linear approximation, least squares approximation, neural networks and the wavelet transform. These methods are chosen since each has a different physical basis and thus extracts and uses time series information in a different way.
Abstract Background Tetralogy of Fallot (ToF) patients face an increased risk of sudden cardiac death late after repair. Heart rate turbulence (HRT) indices are well-known predictors of sudden ...cardiac death. We aimed to estimate whether HRT is impaired in repaired ToF patients compared to healthy controls and relate those HRT parameters to already recognized prognostic markers. Methods Continuous ECG recordings were performed in 19 patients late after ToF repair (36.3 ± 12.4 years, 26.6 ± 7.1 years after repair) and 20 age-matched healthy controls (40.8 ± 8.1 years). Turbulence slope (TS) and onset (TO), frequency and time domain heart rate variability parameters and QRS duration were estimated. Volumes of the right (RV) and left ventricle (LV) and ejection fraction (EF) were assessed by cardiovascular magnetic resonance imaging. Cardiopulmonary exercise testing was used to estimate peak oxygen consumption (VO2 ) and VE/VCO2 slope. Results TS (15.95 ± 9.41 vs 28.73 ± 12.24 ms/RRI, p = 0.0007) and TO (− 0.98 ± 2.06% vs − 3.45 ± 3.25%, p = 0.007) were found to be significantly different between ToF patients and controls. TO correlated with LVEF ( r = 0.47, p < 0.05), LVSVi ( r = 0.50, p = 0.03), RVEF ( r = 0.53, p = 0.02), peak VO2 ( r = 0.50, p = 0.05), VE/VCO2 slope ( r = − 0.55, p = 0.03) and with heart rate variability frequency domain indices (log LF, r = 0.47, p = 0.04, log HF, r = 0.56, p = 0.01). Conclusion HRT indices are impaired in ToF patients late after surgical repair compared to healthy controls and relate to coexisting haemodynamic, ventilatory and autonomic impairment. A clinical prognostic role of HRT may be speculated, which warrants further investigation.
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