ABSTRACT
The sub-cycle dynamics of electrons driven by strong laser fields is central to the emerging field of attosecond science. We demonstrate how the dynamics can be probed through high-order harmonic generation, where different trajectories leading to the same harmonic order are initiated at different times, thereby probing different field strengths. We find large differences between the trajectories with respect to both their sensitivity to driving field ellipticity and resonant enhancement. To accurately describe the ellipticity dependence of the long trajectory harmonics we must include a sub-cycle change of the initial velocity distribution of the electron and its excursion time. The resonant enhancement is observed only for the long trajectory contribution of a particular harmonic when a window resonance in argon, which is off-resonant in the field-free case, is shifted into resonance due to a large dynamic Stark shift.
ABSTRACT
We generate high-order harmonics at high pulse repetition rates using a turnkey laser. High-order harmonics at 400 kHz are observed when argon is used as target gas. In neon, we achieve generation of photons with energies exceeding 90 eV (â¼13 nm) at 20 kHz. We measure a photon flux of up to 4.4 × 10(10) photons per second per harmonic in argon at 100 kHz. Many experiments employing high-order harmonics would benefit from higher repetition rates, and the user-friendly operation opens up for applications of coherent extreme ultra-violet pulses in new research areas.
ABSTRACT
The protective effect of Berotec, Berodual and Atrovent (Boehringer-Ingelheim) were compared in asthmatics, before inducing airways obstruction with acetylcholine. Three groups (8 patients in each) were chosen. They were given two doses of the above drugs, from originally packed under pressure bottles, 30 minutes before acetylcholine inhalation. All the drugs provided sufficient protection against the induced acetylcholine obstruction of airways. No significant differences were found in protective effect.
Subject(s)
Asthma/prevention & control , Atropine Derivatives/therapeutic use , Bronchodilator Agents , Fenoterol/therapeutic use , Ipratropium/therapeutic use , Adult , Drug Combinations/therapeutic use , Female , Forced Expiratory Volume , Humans , MaleABSTRACT
The bronchodilatating effect of one single dose of Berotec, Berodual and Atrovent, has been studied in 28 patients suffering from bronchial asthma. All three drugs had a beneficial bronchodilatating effect lasting for 300 minutes. There were no statistically significant changes between the drugs studied.
Subject(s)
Asthma/drug therapy , Atropine Derivatives/pharmacology , Bronchodilator Agents , Fenoterol/pharmacology , Ipratropium/pharmacology , Adult , Bronchodilator Agents/adverse effects , Drug Combinations/adverse effects , Drug Combinations/pharmacology , Female , Fenoterol/adverse effects , Humans , Ipratropium/adverse effects , Male , Pulse/drug effectsABSTRACT
By tussiphonography the voluntarily induced cough sound was registered in the course of asthmatic attacks and in the state of quinescence. Evaluation of the recordings revealed that in the course of the asthmatic attack, the intensity of voluntarily induced cough sound was significantly decreased.
