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We present a control system, which allows an automatic optimization of the pulse train stability in a mode-locked laser cavity. In order to obtain real-time corrections, we chose a closed loop approach. The control variable is the cavity length, mechanically adjusted by gear system acting on the rear cavity mirror, and the controlled variable is the envelope modulation of the mode-locked pulse train. Such automatic control system maintains the amplitude of the mode-locking pulse train stable within a few percent rms during the working time of the laser. Full implementation of the system on an Nd:yttrium lithium fluoride actively mode-locked laser is presented.
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Fluoruros , Rayos Láser , Litio , Neodimio , Itrio , Factores de TiempoRESUMEN
In this paper we present Hugoniot data for plastic foams obtained with laser-driven shocks. Relative equation-of-state data for foams were obtained using Al as a reference material. The diagnostics consisted in the detection of shock breakout from double layer Al/foam targets. The foams [poly(4-methyl-1-pentene) with density 130 > rho > 60 mg/cm3] were produced at the Institute of Laser Engineering of Osaka University. The experiment was performed using the Prague PALS iodine laser working at 0.44 microm wavelength and irradiances up to a few 10(14) W/cm2. Pressures as high as 3.6 Mbar (previously unreached for such low-density materials) where generated in the foams. Samples with four different values of initial density were used, in order to explore a wider region of the phase diagram. Shock acceleration when the shock crosses the Al/foam interface was also measured.
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AIM: To study informative value of dobutrex echocardiography (DEC) in diagnosis of myocardial ischemia and viability, in prognostication of angina pectoris and myocardial infarction (MI), evaluation of DEC side effects. MATERIAL AND METHODS: DEC was conducted in 74 patients with unconfirmed diagnosis (they had ischemic heart disease risk factors, atypical cardialgia) and 32 ischemic heart disease patients. RESULTS: DEC proved to be an effective diagnostic tool in diagnosis of myocardial ischemia in patients with new-onset atypical cardialgia (informative value 73.6%). This test gives prognosis of the disease and improves treatment policy in patients with angina of effort and MI. The most serious and frequent side effects of DEC arising at the highest dobutrex dose were paroxysmal tachycardias (3.76%) and ventricular arrhythmias (6.58%). In most cases (99.1%) they discontinued after the test and did not require antiarrhythmic treatment. Thus, the test is relatively safe. CONCLUSION: Echocardiography with dobutrex load should be used in practical cardiology more intensively.