Mid-IR Kerr-Lens Mode-Locked Polycrystalline Cr2+:ZnS Laser With 29 fs Pulse Duration

2015 ◽  
Author(s):  
S. Vasilyev ◽  
M. Mirov ◽  
V. Gapontsev
Keyword(s):  
Pulse Duration

Laser pulse duration effects in Xe2+ ions induced by multiphoton absorption at 0.53 μm

1983 ◽  
Vol 44 (11) ◽  
pp. 1247-1255 ◽  
Author(s):  
A. L'Huillier ◽  
L.A. Lompre ◽  
G. Mainfray ◽  
C. Manus
Keyword(s):  
Laser Pulse ◽  
Pulse Duration ◽  
Laser Pulse Duration ◽  
Multiphoton Absorption

P6595The optogenetic defibrillation of ventricular arrhythmia in myocardial infarction rats in vivo

2019 ◽  
Vol 40 (Supplement_1) ◽  
Author(s):  
X I Wang ◽  
Y Cheng ◽  
P Rao ◽  
L Wang
Keyword(s):  
Light Intensity ◽  
Ventricular Arrhythmia ◽  
Sinus Rhythm ◽  
Pulse Duration ◽  
Underlying Mechanism ◽  
Blue Laser ◽  
Continuous Illumination ◽  
Threshold Intensity ◽  
Systemic Delivery ◽  
Significant Difference

Abstract Introduction Optogenetics is a low-invasive, flexible and highly selective intervention that enables electrical excitation with light on myocardium overexpressing light-sensitive proteins. Optical illumination can control the simultaneous exciting of the whole myocardium under the spot, which is more conducive to recovery from electrical disturbance to sinus rhythm. Purpose We explored optogenetic defibrillation for different illumination parameters how to affect defibrillation rates and the possible mechanism of continuous illumination defibrillation. Methods Systemic delivery via right jugular vein injection of (AAV9-CAG-hChR2(H134R)-mCherry) were performed in juvenile SD rats to achieve the light sensitive protein Channelrhodopsin-2 (ChR2) transfer throughout the whole heart. We intubated and ventilated rats, opened chest and recorded the ECG. After ligation of the left anterior descending coronary artery, ventricular arrhythmia was induced by electrical burst stimulation (10v, 50Hz, 2s). Cardiac epicardium illumination with 470nm blue laser was performed to investigate the effects of optogenetic defibrillation and its underlying mechanism. Every heart accepted 30 pulses of 20ms duration on 8Hz to test the light intensity threshold for 1:1 capture. Different illumination modes of multiple light intensity (2,4,8,10,20 times threshold intensity), pulse duration (20, 50, 200, 500 and 1000ms) and illumination position (RV apex, RV, RVOT, septum, LV) were applied in each attempt for 4 repetitions with 1 s interval. Results We demonstrated that ventricular arrhythmias could be terminated by illumination of the right ventricle at 20 times threshold intensity in 1s (figure A) with the successful defibrillation rate of 95±2.673% (mean ±SEM; N=7). Herein, the successful optogenetic defibrillation rate was strongly depending on light intensity (N=5, n=50 episodes, p=0.0118) and duration of illumination (N=5, n=50 episodes, p<0.0001) (figure B.C). Notably when there were higher intensity and longer pulse duration, the higher defibrillation rate appeared. There was no significant difference in the defibrillation rate among different illumination positions (N=5, n=25episodes per position, p=0.1177) (figure D). To explore the underlying mechanism of optogenetic defibrillation, we performed the same illumination mode during sinus rhythm in 2 rats (figure E. F. G). We observed that higher light intensity and longer pulse duration were more conducive to induce an episode of higher frequency focal excitement. Views of optogenetic defibrillation Conclusions We demonstrated that optogenetic defibrillation is a highly effective intervention and the possible mechanism is partly attributed to overdrive suppression. We believe that optogenetic approach is potentially to be translated into more efficient and pain-free clinical termination of ventricular arrhythmia. Acknowledgement/Funding The national natural science foundation of China (81772044)

Single shot measurement of light pulse duration by detection of excited acoustic wave

1989 ◽  
Vol 22 (10) ◽  
pp. 1423-1428 ◽  
Author(s):  
I Buchvarov ◽  
S M Saltiel ◽  
V E Gusev ◽  
V T Platonenko
Keyword(s):  
Acoustic Wave ◽  
Pulse Duration ◽  
Light Pulse ◽  
Single Shot

P6547The energy cost of His bundle pacing can be curtailed

2019 ◽  
Vol 40 (Supplement_1) ◽  
Author(s):  
F Zanon ◽  
L Marcantoni ◽  
G Pastore ◽  
E Baracca ◽  
C Picariello ◽  
...  
Keyword(s):  
Pulse Duration ◽  
Safety Margin ◽  
Significant Saving ◽  
His Bundle ◽  
His Bundle Pacing ◽  
On Demand ◽  
Mild Reduction ◽  
Ventricular Activation ◽  
The Individual ◽  
Current Drain

Abstract Introduction His bundle pacing (HBP) allows physiological ventricular activation and prevents the electrical and mechanical desynchronization generally induced by myocardial stimulation, which can increase the risk of atrial fibrillation and heart failure. On the other hand, reliable HBP capture often requires higher energy than conventional myocardial pacing. This reduces the expected life of the stimulator and might limit the diffusion of HBP in the clinical practice. Purpose Decreasing HBP current drain by careful management of stimulation safety margin and pulse duration. Methods In 28 patients undergoing DDD pacing with HBP, a third lead was implanted in RV apex to provide back-up pacing on demand. HBP and apical leads were connected, respectively, to the V1 and V2 channels of a 3-chamber stimulator. When HBP was effective, apical sensing occurred within the VV delay and prevented V2 stimulation. In contrast, in case of HBP failure, V2 sensing was missing and apical back-up pacing was promptly delivered at the end of the VV delay. The availability of a back-up pulse on demand allowed reducing the HBP safety margin with no risk. Furthermore, the individual HBP strength-duration curve was derived in the aim of optimizing the Hisian pulse parameters, which are the major determinants of the device current drain. Results Correct back-up inhibition by successful HBP and stimulation in the event of capture loss was achieved in all the patients. The latency from Hisian pacing to apical sensing averaged 96±14 ms. According to the pacemaker counters, no back-up pulse was delivered in daily life in 59% of patients. In the remaining, the prevalence of back-up stimulation never exceeded 15% of paced ventricular cycles. The high HBP threshold was essentially due to an increased rheobase (1.2±0.6 V), while the chronaxie ranged from 0.30 to 0.53 ms in 71% of patients (median 0.44 ms), exceeding 0.6 ms only in 29% of the cases. An average current saving of 5.4±3.0 μA was obtained at the expense of a mild reduction in HBP safety margin (from 1.6±0.2 to 1.4±0.1 times). HBP and apical back-up Conclusions Back-up stimulation on demand is a reliable option to decrease HBP current drain and prolong the stimulator service life with full safety. In most of the cases, significant saving can be achieved by pulse shortening, as the chronaxie time is in the same range as with myocardial stimulation and longer pulses are not required. A pulse duration exceeding 0.6 ms is indicated in less than 1/3 of the implants.

Pulse Duration of Superradiance on Molecular Nitogen Ions in Air Laser Plasma

2021 ◽  
Author(s):  
I. A. Zyatikov ◽  
V. F. Losev ◽  
V. E. Prokopiev ◽  
D. M. Lubenko ◽  
E. A. Sandabkin
Keyword(s):  
Pulse Duration ◽  
Laser Plasma

Effect of laser pulse duration on properties of metal and metal carbide nanoparticles obtained by laser in liquid synthesis

2021 ◽  
Vol 138 ◽  
pp. 106916
Author(s):  
M. Curcio ◽  
A. De Bonis ◽  
A. Santagata ◽  
A. Galasso ◽  
R. Teghil
Keyword(s):  
Laser Pulse ◽  
Pulse Duration ◽  
Laser Pulse Duration ◽  
Metal Carbide
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