40 research outputs found
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Optimization of the cooling profile to achieve crack-free Yb:S-FAP crystals
Yb:S-FAP [Yb{sup 3+}:Sr{sub 5}(PO{sub 4}){sub 3}F] crystals are an important gain medium for diode-pumped laser applications. Growth of 7.0 cm diameter Yb:S-FAP crystals utilizing the Czochralski (CZ) method from SrF{sub 2}-rich melts often encounter cracks during the post growth cool down stage. To suppress cracking during cool down, a numerical simulation of the growth system was used to understand the correlation between the furnace power during cool down and the radial temperature differences within the crystal. The critical radial temperature difference, above which the crystal cracks, has been determined by benchmarking the simulation results against experimental observations. Based on this comparison, an optimal three-stage ramp-down profile was implemented and produced high quality, crack-free Yb:S-FAP crystals
Genotype-phenotype correlation of 2q37 deletions including NPPC gene associated with skeletal malformations
Coordinated bone growth is controlled by numerous mechanisms which are only partially understood because of the involvement of many hormones and local regulators. The C-type Natriuretic Peptide (CNP), encoded by NPPC gene located on chromosome 2q37.1, is a molecule that regulates endochondral ossification of the cartilaginous growth plate and influences longitudinal bone growth. Two independent studies have described three patients with a Marfan-like phenotype presenting a de novo balanced translocation involving the same chromosomal region 2q37.1 and overexpression of NPPC. We report on two partially overlapping interstitial 2q37 deletions identified by array CGH. The two patients showed opposite phenotypes characterized by short stature and skeletal overgrowth, respectively. The patient with short stature presented a 2q37 deletion causing the loss of one copy of the NPPC gene and the truncation of the DIS3L2 gene with normal CNP plasma concentration. The deletion identified in the patient with a Marfan-like phenotype interrupted the DIS3L2 gene without involving the NPPC gene. In addition, a strongly elevated CNP plasma concentration was found in this patient. A possible role of NPPC as causative of the two opposite phenotypes is discussed in this study
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Full System Operations of Mercury; A Diode-Pumped Solid-State Laser
Operation of the Mercury laser with two amplifiers activated has yielded 30 Joules at 1 Hz and 12 Joules at 10 Hz and over 8 x 10{sup 4} shots on the system. Static distortions in the Yb:S-FAP amplifiers were corrected by magneto rheological finishing technique
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The Mercury Project: A High Average Power, Gas-Cooled Laser For Inertial Fusion Energy Development
Hundred-joule, kilowatt-class lasers based on diode-pumped solid-state technologies, are being developed worldwide for laser-plasma interactions and as prototypes for fusion energy drivers. The goal of the Mercury Laser Project is to develop key technologies within an architectural framework that demonstrates basic building blocks for scaling to larger multi-kilojoule systems for inertial fusion energy (IFE) applications. Mercury has requirements that include: scalability to IFE beamlines, 10 Hz repetition rate, high efficiency, and 10{sup 9} shot reliability. The Mercury laser has operated continuously for several hours at 55 J and 10 Hz with fourteen 4 x 6 cm{sup 2} ytterbium doped strontium fluoroapatite (Yb:S-FAP) amplifier slabs pumped by eight 100 kW diode arrays. The 1047 nm fundamental wavelength was converted to 523 nm at 160 W average power with 73% conversion efficiency using yttrium calcium oxy-borate (YCOB)
A microdosimetry application for Microbeam Radiation Therapy dose delivery using TOPAS
Microbeam Radiation Therapy as a cancer treatment is developing fast due to its high therapeutic effect. This work simulates the MRT setup and the multi-slit collimator used in the creation of microbeams with the aid of TOPAS. TOPAS is a Geant4-based Monte Carlo extension developed to make simulations more readily available to both research and clinical medical physicists, as well as to extend its functionality. A multi-slit collimator is modelled to produce x-ray microbeams with a width of 50 μm and a centre to centre spacing of 400 μm. The energies range from 0 to 600 keV, and they are sampled using the synchrotron-wiggler generated spectrum employed at the biomedical facility of the European Synchrotron Radiation Facility (ESRF) in Grenoble, France. This work aims to identify the accuracy of the dose deposition curves and peak to valley dose ratios (PVDRs) obtained with TOPAS. The PVDRs decreased with depth but increased prior to phantom exit due to the absence of back scattering. The simulated results are in line with published simulated and empirical findings, which suggest that TOPAS can be satisfactorily used as a tool for the calculation of the percentage depth dose and PVDRs at the energies considered in this study
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