First Measurement of a Long-Lived π

The adapted DIRAC experiment at the CERN PS accelerator observed for the first time long-lived hydrogenlike π^{+}π^{-} atoms, produced by protons hitting a beryllium target. A part of these atoms crossed the gap of 96 mm between the target and a 2.1 µm thick platinum foil, in which most of them dissociated. Analyzing the observed number of atomic pairs, n_{A}^{L}=436_{-61}^{+157}|_{tot}, the lifetime of the 2p state is found to be τ_{2p}=(0.45_{-0.30}^{+1.08}|_{tot})×10^{-11} s, not contradicting the corresponding QED 2p state lifetime τ_{2p}^{QED}=1.17×10^{-11} s. This lifetime value is three orders of magnitude larger than our previously measured value of the π^{+}π^{-} atom ground state lifetime τ=(3.15_{-0.26}^{+0.28}|_{tot})×10^{-15} s. Further studies of long-lived π^{+}π^{-} atoms will allow us to measure energy differences between p and s atomic states and so to discriminate between the isoscalar and isotensor ππ scattering lengths with the aim to check QCD predictions.

[Automatic analysis of interference pattern: principles and applications]. / Análisis automático del patrón interferencial: principios y aplicaciones.

INTRODUCTION: The signals obtained during conventional needle examination are usually assessed subjectively by the neurophysiologist. Buchthal's approach allows quantification of several motor unit parameters during mild effort. DEVELOPMENT: The automatic methods of analysis of the EMG interference pattern (IP), in particular Turns/Amplitude, give us information concerning the number, firing rate, and morphology of the motor units, as well as the recruitment pattern at different degrees of effort. In pathological conditions, the changes in the IP allow distinction between myopathies and neuropathies. CONCLUSION: These methods, which complement other methods of motor unit analysis, have also proved to be excellent for follow up studies.

Prolongation of the QTc interval during alcohol withdrawal syndrome.

BACKGROUND: Cardiac arrhythmias might explain cases of sudden death in alcoholics during ethanol abstinence. AIM OF STUDY: To evaluate QT interval (and its outcome) in patients with alcohol withdrawal syndrome. PATIENTS AND METHODS: Sixty-two patients (52 male and 10 female, mean age 43.7 years, range 18-71 years), admitted to the hospital as a result of alcohol abstinence syndrome (tremulousness in 7 cases, agitation in 12 cases, delirium tremens in 11 cases, and seizures in 32) were studied. The QT interval was measured on 12 lead ECGs performed on admission in all cases. QTc was obtained using Bazett's formula. In 27 patients a second ECG was performed during hospital stay. Results. Mean QTc interval on admission was 439 +/- 32 ms (range 350-525 ms); 29 patients (46.8%) showed a prolonged (> 440 ms) QTc interval. No significant differences were observed between patients with normal and high QTc values as regards to age, sex, type of withdrawal syndrome, duration of abstinence, liver function tests, serum electrolytes or blood cell counts. In cases where two ECG recordings could be evaluated (n = 27), the mean QTc interval was significantly shorter in the latter than in the former (417 +/- 26 ms versus 447 +/- 30 ms, respectively, p < 0.001). Eight patients found to have prolonged QTc on admission had a second ECG performed on them after complete recovery from withdrawal symptoms. In all these cases the QTc interval eventually became normal. CONCLUSION: The QTc interval is frequently prolonged during alcohol withdrawal syndrome and tends to become normal over time, along with remission of abstinence symptoms.