We compare for the first time the influence of different Yb:YAG gain media on the performance of a large-area, high average-power laser system with an output energy of up to 6 J. Monocrystalline ...slabs grown by a new technique without central growth defect are compared with ceramics. Small signal gain, maximum output energy and thermal lensing are compared for ceramic slabs with co-sintered amplified spontaneous emission (ASE) absorber cladding, monocrystalline slab with and without optically bonded ASE absorber cladding, and surface structured monocrystalline slabs. We show that these large monocrystals with optically bonded absorber cladding have similar performance to cladded ceramics, so far the only material for high-energy Yb:YAG lasers.
An experimental platform for laser-driven ion (sub-MeV) acceleration and potential applications was commissioned at the HiLASE laser facility. The auxiliary beam of the Bivoj laser system operating ...at a GW level peak power (~10 J in 5–10 ns) and 1–10 Hz repetition rate enabled a stable production of high-current ion beams of multiple species (Al, Ti, Fe, Si, Cu, and Sn). The produced laser–plasma ion sources were fully characterized against the laser intensity on the target (1013–1015 W/cm2) by varying the laser energy, focal spot size, and pulse duration. The versatility and tuneability of such high-repetition-rate laser–plasma ion sources are of potential interest for user applications. Such a statistically accurate study was facilitated by the large amount of data acquired at the high repetition rate (1–10 Hz) provided by the Bivoj laser system.
Lung Allocation Score System: First Italian Experience Palleschi, A.; Benazzi, E.; Rossi, C.F. ...
Transplantation proceedings,
January-February 2019, 2019 Jan - Feb, 2019-01-00, 20190101, Letnik:
51, Številka:
1
Journal Article
Recenzirano
Lung transplantation is an established therapeutic option for patients with end-stage pulmonary disease. In May 2005, the lung allocation score (LAS) was introduced in the United States to maximize ...the benefit to the recipient population and reduce waiting list mortality. The LAS has been applied in a region of Italy since March 2016 on a provisional basis.
The aims of the study were describing waiting list characteristics and short-term outcomes after lung transplantation before and after LAS introduction.
All the patients who received transplants between January 1, 2011, and March 15, 2017, were included in our retrospective study. The study population was divided into 2 cohorts (historical cohort and post-LAS cohort) and a comparison among the main perioperative data was performed.
The historical cohort consisted of 415 patients on the waiting list with 91 deaths and 199 lung transplants; the post-LAS cohort consisted of 134 patients with 10 deaths on the waiting list and 51 transplants. Median waiting time and mortality on the list decreased from 223 to 106 days (P = .03) and from 11.2% to 7.5% (P > .05), respectively. The transplantation rate increased from 25% to 38% (P = .001) and the probability to receive a transplant in the first year in the post-LAS era increased significantly (P = .004).
The results of the introduction of the LAS system in our region are encouraging and have not shown any adverse short-term effects. The regional coordination decided to prolong the experimental application of LAS in order to accumulate more data and to evaluate medium-term outcomes.
•Donor lung availability is limited; a high number of patients die on the waiting list.•Lung allocation score (LAS) has been introduced to reduce waiting list mortality.•First Italian experience with LAS began in 2016.•Outcomes after 1 year since implementation of LAS are encouraging.
Mycotic aneurysm of the hepatic artery (HA) is a rare, unpredictable, and potentially lethal complication of liver transplantation (LT). Pediatric LT is not exempt from it but the related literature ...is rather scanty. We present our experience with post‐LT mycotic aneurysm of the HA in pediatric age, describing four cases occurred with a special focus on the possible risk factors for its development and a proposal for the management of high‐risk recipients.
The time-resolved measurements of thermally induced wavefront aberrations in a cryogenically cooled Yb:YAG crystal are presented in dependence on temperature in the range between 250 and 130 K under ...non-lasing condition. A wavefront sensor was utilized to determine the wavefront aberrations. The wavefront distortions were experimentally studied for a cryogenically cooled Yb:YAG crystal in detail for the first time. The wavefront aberrations were significantly reduced at cryogenic temperatures including defocus which was the dominant aberration and which was responsible for the so-called thermal lensing effect. We found that defocus aberration is caused not only by thermally induced effects (responsible for thermal lens), but also by electronically induced change in the refractive index due to excitation of ion activators which is responsible for the electronic lensing. Nevertheless, at pumping intensity of 6.3 kW/cm
2
and repetition rate of 100 Hz thermal effects were the dominant one. In addition, an improvement in the Strehl ratio along with an increase in absorbed pump energy was observed while the temperature of the gain medium was decreased. The measurements clearly show the advantages of cryogenic cooling of laser-active media for beam quality improvement.
An experimental platform for laser-driven ion (sub-MeV) acceleration and potential applications was commissioned at the HiLASE laser facility. The auxiliary beam of the Bivoj laser system operating ...at a GW level peak power (~10 J in 5–10 ns) and 1–10 Hz repetition rate enabled a stable production of high-current ion beams of multiple species (Al, Ti, Fe, Si, Cu, and Sn). The produced laser–plasma ion sources were fully characterized against the laser intensity on the target (10sup.13–10sup.15 W/cmsup.2) by varying the laser energy, focal spot size, and pulse duration. The versatility and tuneability of such high-repetition-rate laser–plasma ion sources are of potential interest for user applications. Such a statistically accurate study was facilitated by the large amount of data acquired at the high repetition rate (1–10 Hz) provided by the Bivoj laser system.
A major challenge the HiPER 1 project is facing is to derive laser architectures satisfying simultaneously all HiPER requirements; among them, high wall-plug efficiency (15 to 20%) and repetition ...rate (around 10 Hz) are the most challenging constraints. Several groups over the world are actively pursuing research in the field of High average power Diode Pumped Solid State Lasers (DPSSL) 2. We propose a comprehensive solution for a 1 kJ DPSSL beamline as the unit brick of a 12 beams bundle.
The goal of the HiLASE project is to design and optimize parameters for 100 J 10 Hz Yb:YAG laser amplifiers that are scalable to the kJ regime. The HiLASE power amplifier design is based on a ...cryogenic, gas-cooled multi-slab concept. Simulation results of the 10 J pre-amplifier agree very well with experimental measurements. In order to fulfil the very demanding requirements, which include wall-plug efficiency > 12% and repetition rates up to 10 Hz, HiLASE and RAL teams are closely working together and developing the approach described here.
One of the biggest challenges the HiPER project is facing is to identify a laser architecture that meets all the demanding requirements. Among those are high wall-plug efficiency (15 to 20%) and ...repetition rate (5 to 10 Hz). In order to perform this task, four teams from the co-authors' institutions are working together and exploring several approaches described here.
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