Observation of 7pP23/2→7dD2 optical transitions in 209 and 210 francium isotopes.

We report on the direct experimental observation of the 7pP23/2→7dD2 optical transitions in 209 and 210 francium isotopes. By continuously monitoring the fluorescence emitted by the isotopes collected in a magneto-optical trap (MOT), the electric dipole transitions 7pP23/2→7dD25/2 of Fr209, not yet experimentally observed, and 7pP23/2→7dD25/2, 7pP23/2→7dD25/2 of Fr210 were detected as sub-Doppler depletion dips of the cold atom population. This approach allowed unambiguous identification of the excited state hyperfine structures, even in the absence of a large stable vapor. Our findings demonstrate the effectiveness and the flexibility of fluorescence monitoring of trap depletion upon laser excitation, and broaden the experimental knowledge of francium isotopes and their electronic and nuclear properties. These results will have a relevant impact on ongoing researches for low-energy testing of fundamental symmetries with francium, from atomic parity non-conservation to the electron dipole moment.

Light desorption from an yttrium neutralizer for Rb and Fr magneto-optical trap loading.

We present here the first evidence of photodesorption induced by low-intensity non-resonant light from an yttrium thin foil, which works as a neutralizer for Rb and Fr ions beam. Neutral atoms are suddenly ejected from the metal surface in a pulsed regime upon illumination with a broadband flash light and then released in the free volume of a pyrex cells. Here atoms are captured by a Magneto-Optical Trap (MOT), which is effectively loaded by the photodesorption. Loading times of the order of the flash rise time are measured. Desorption is also obtained in the continuous regime, by exploiting CW visible illumination of the metallic neutralizer surface. We demonstrate that at lower CW light intensities vacuum conditions are not perturbed by the photodesorption and hence the MOT dynamics remains unaffected, while the trap population increases thanks to the incoming desorbed atoms flux. Even with the Y foil at room temperature and hence with no trapped atoms, upon visible illumination, the number of trapped atoms reaches 10(5). The experimental data are then analyzed by means of an analytical rate equation model, which allows the analysis of this phenomenon and its dynamics and allows the determination of critical experimental parameters and the test of the procedure in the framework of radioactive Francium trapping. In this view, together with an extensive investigation of the phenomenon with (85)Rb, the first demonstration of the photodesorption-aided loading of a (210)Fr MOT is shown.

Explosive vaporization of metallic sodium microparticles by CW resonant laser radiation.

Explosive vaporization of metallic Na microparticles stimulated by resonant cw laser radiation has been observed in a glass cell. Vaporization occurs at low laser-power density. The effect consists in the generation of optically thick and sharply localized Na vapor clouds propagating in the cell against the laser beam. The effect is explained by laser excitation of Na atoms, which collide onto the surface of the microparticles and transfer their internal energy. This causes other atoms to be vaporized and to continue the avalanche process.

A reference data base for multilead electrocardiographic computer measurement programs.

In an effort to standardize and evaluate the performance of electrocardiographic computer measurement programs, a 15 lead reference library has been developed based on simultaneously recorded standard 12 lead and orthogonal XYZ lead data. A set of 250 electrocardiograms (ECGs) with selected abnormalities was analyzed by a group of five referee cardiologists and 11 different 12 lead and 6 XYZ computer programs. Attention was focused on the exact determination of the onsets and offsets of P, QRS and T waves. The referees performed their task on highly amplified, selected complexes from the library in a two round process. Median results of the referees coincided best with the median derived from all programs. An analysis of stability proved that the combined program median was a robust reference. However, some individual program results were widely divergent. Paired t tests demonstrated earlier onset for P and QRS (p less than 0.001), as well as later offset for P and T waves in the median 12 lead than in the XYZ results. Significant differences also existed among results obtained by programs analyzing all standard ECG leads at one time, the so-called multilead programs, and those obtained by the conventional standard three lead analysis programs. As a consequence, the derived P, PR, QRS and QT interval measurements varied quite widely among the various programs. Significant differences were also observed among measurements of Q, R and S duration. Some programs showed Q waves that were on the average 6 ms (p less than 0.001) longer than those of others. This may significantly influence diagnostic performance.(ABSTRACT TRUNCATED AT 250 WORDS)

Development of a reference library for multi-lead ECG measurement programs.

The development of a data base is described which can be used as common reference for ECG computer programs analyzing 12 or 15 simultaneously recorded leads. This data base is an extension of the 3-lead CSE reference library, described previously.

Prognostic value of ventricular arrhythmias and transient ST-T changes after myocardial infarction: a two-year follow-up with ambulatory ECG recording.

The aim of this study is to evaluate the frequency and prognostic significance of ventricular arrhythmias (VA) and of ST-T changes found during 24-h ECG recording in patients who survived an acute myocardial infarction. Eighty-nine patients (2 females and 87 males) discharged from hospital after acute myocardial infarction were studied. Mean age was 52.2 years (SD +/- 10) with a range of 26-68. Serial observations were carried out at 1, 2, 3, 6, and 12 months after the acute event. Eight patients died during the first two years of follow-up, of these, 2 deaths were of noncardiac origin: one was due to gastric carcinoma and the other to pulmonary neoplasm. Of the 6 cardiac deaths, 4 were sudden and unexpected and 2 were due to reinfarction. Statistical analysis of the results obtained in the first three months of follow-up has not shown any significant correlation between pathologic patterns and cardiac death. In the second period we found a statistically significant relationship between cardiac death and multiform VPBs (p less than 0.05), CVA (p less than 0.05), and ST-T changes (p less than 0.05). More significant was the correlation between cardiac death and the presence at the same time of ST-T changes and multiform VPBs (p less than 0.01).

Establishment of a reference library for evaluating computer ECG measurement programs.

As a result of an international cooperative project entitled "Common Standards for Quantitative Electrocardiography" (CSE), an ECG reference data base has been established with the aim of standardizing computer-derived ECG measurements. The objective of the project is to reduce the wide variation in wave measurements currently obtained by ECG analysis programs. A library of 250 ECGs with selective ECG abnormalities was established and a comprehensive reviewing scheme was devised for the visual determination of the onsets and offsets of P, QRS, and T. This task was performed by a board of cardiologists on highly amplified, selected complexes from the library. A subset was examined in order to study beat-to-beat and intraobserver variability. By using a modified Delphi approach, individual outlying point estimates were eliminated in four successive rounds. In this way final referee estimates were obtained which proved to be highly reproducible and precise. A reference library has thereby been developed which allows testing of the performance of ECG measurement programs and is a useful instrument in establishing recommendations for more precise measurement rules and definitions.

The intraarterial blood pressure monitoring in the evaluation of patients with dizziness and/or fainting.

Ambulatory blood pressure (BP) monitoring has been extensively utilized, so far, for studying BP profile and hypotensive treatment in arterial hypertension. In this paper, preliminary data will be reported from a clinical study on the possible contribution of the combined ECG and BP monitoring in clarifying mechanisms of dizziness in patients with multiple or complex cardiovascular problems. Results are shown of three patients with ischaemia, arrhythmias and/or episodes of hypotension, and of three patients with borderline hypertension and marked fluctuations of BP.

Clinical experience with a new dynamic display system for ambulatory ECG recordings.

The authors present the results of clinical experience with a new display for ECG signal presentation in ambulatory ECG monitoring. The new method has been devised by adding to contourography the dynamic effect produced by image movement and the perspective effect produced by pseudo-tridimensional presentation. The system has been developed using a microprocessor, a dynamic memory and an arithmetic unit which sends the signal on a CRT screen. Clinical experience, based upon 150 analyses, demonstrates the new method's marked efficiency in presenting rhythm disturbances and particularly ST-T segment alterations. Clinical validation has been performed comparing the results of 50 tapes analysed both with the new method and with different commercial systems. The new method provides useful information as to ST-T segment in 98% of cases and as to rhythm disturbances in 90%, while commercial systems reveal ST-T alterations in 84% and arrhythmias in 70% This method, being devoid of automaticity, does not yield false positives; dynamic and pseudo-tridimensional visualization of ECG signal allow the operator to perceive with high sensitivity alterations of the observed tracing.

[A new system for dynamic electrocardiography. First clinical trial]. / Unovo sistema per elettrocardiografia dinamica. Prima esperienza clinica.

The development of a reliable system for analysis of ambulatory ECG recordings, for evaluation of arrhythmias and ST-T segment changes is a great challenge for technology and cardiovascular medicine. Signal superimposition or AVSEP system, conceived by Norman J. Holter, has been widely used and is employed even in recent sophisticated devices for analysis of ambulatory ECG recordings. As an alternative way we have chosen contourography, known since 1966, enhanced by a dynamic and perspective effect (Fig. 1). Figure 2 shows the display mechanism of the ECG signal. Cardiac cycles are continuously sampled, triggered and positioned along the running time axis. The QRS complexes undergo progressive amplitude decrease while "sliding" toward a viewpoint adjustable by the operator (Fig. 3). As memory contains a fixed number of cycles, the latest cycle enters the screen while the oldest falls out. Instead of being superimposed as in AVSEP system, cardiac cycles are displayed separately. In this way it is possible to make comparisons between one cycle and another or among different areas of the ECG tracing. At any instant, the tracing can be stopped, and an intensified area of interest can be recorded on a paper strip in a standard fashion (Fig. 4). A clinical comparison has been performed between this device and two different commercial systems; 25 tapes, 24 hours each, have been separately analyzed by two cardiologists with the Avionics system and 25 with the Pathfinder, and then with the new system. Each operator was not aware of the results of the other one.(ABSTRACT TRUNCATED AT 250 WORDS)