Angle-resolved energy spectra of high-order above-threshold ionization are calculated in the direction of the laser polarization for a linearly polarized four-cycle laser pulse (two cycles FWHM) as a function of the carrier-envelope relative phase (absolute phase). The spectra exhibit a characteristic left-right (backward-forward) asymmetry, which should allow one to determine the value of the absolute phase in a given experiment by comparison with the theoretical spectra. A classical analysis of the spectra calculated is presented. High-energy electron emission is found to occur in one or two ultrashort (< inverted exclamation mark<< 0.7 fs) bursts. In the latter case, the spectra display a peak structure whose analysis reveals a time-domain image of electron emission.

ObjectiveThe aim of this study was to evaluate the diagnostic potential of low-dose adenosine stress echocardiography in detection of myocardial viability.BackgroundVasodilation through low dose dipyridamole infusion may recruit contractile reserve by increasing coronary flow or by increasing levels of endogenous adenosine.MethodsForty-three patients with resting dyssynergy, due to previous myocardial infarction, underwent low-dose adenosine (80, 100, 110 mcg/kg/min in 3 minutes intervals) echocardiography test. Gold standard for myocardial viability was improvement in systolic thickening of dyssinergic segments of ≥ 1 grade at follow-up. Coronary angiography was done in 41 pts. Twenty-seven patients were revascularized and 16 were medically treated. Echocardiographic follow up data (12 ± 2 months) were available in 24 revascularized patients.ResultsWall motion score index improved from rest 1.55 ± 0.30 to 1.33 ± 0.26 at low-dose adenosine (p < 0.001). Of the 257 segments with baseline dyssynergy, adenosine echocardiography identified 122 segments as positive for viability, and 135 as necrotic since no improvement of systolic thickening was observed. Follow-up wall motion score index was 1.31 ± 0.30 (p < 0.001 vs. rest). The sensitivity of adenosine echo test for identification of viable segments was 87%, while specificity was 95%, and diagnostic accuracy 90%. Positive and negative predictive values were 97% and 80%, respectively.ConclusionLow-dose adenosine stress echocardiography test has high diagnostic potential for detection of myocardial viability in the group of patients with left ventricle dysfunction due to previous myocardial infarction. Low dose adenosine stress echocardiography may be adequate alternative to low-dose dobutamine test for evaluation of myocardial viability.