Laser-plasma accelerators of only a centimetre's length have produced nearly monoenergetic electron bunches with energy as high as 1 GeV. Scaling these compact accelerators to multi-gigaelectronvolt ...energy would open the prospect of building X-ray free-electron lasers and linear colliders hundreds of times smaller than conventional facilities, but the 1 GeV barrier has so far proven insurmountable. Here, by applying new petawatt laser technology, we produce electron bunches with a spectrum prominently peaked at 2 GeV with only a few per cent energy spread and unprecedented sub-milliradian divergence. Petawatt pulses inject ambient plasma electrons into the laser-driven accelerator at much lower density than was previously possible, thereby overcoming the principal physical barriers to multi-gigaelectronvolt acceleration: dephasing between laser-driven wake and accelerating electrons and laser pulse erosion. Simulations indicate that with improvements in the laser-pulse focus quality, acceleration to nearly 10 GeV should be possible with the available pulse energy.
Correspondence: 1 Corresponding Author: Franco Guscetti, Institut für Veterinärpathologie, Vetsuisse-Fakultät, Universität Zürich, Winterthurerstrasse 268, CH-8057 Zürich, Switzerland, e-mail: ...gufo{at}vetpath.uzh.ch
In most validation studies of tissue microarrays (TMAs), a fixed number of cores with a given diameter are analyzed to determine the degree of accuracy by which the TMA represents the whole section. The statistical model described in the present study predicts this property for various combinations of 2 core sizes (0.6 mm and 1.2 mm) and different core numbers. The model was based on artificial TMA core biopsies generated from Ki-67 and active caspase-3 immunostains of 40 canine lymphoma samples. Positivity was scored on a continuous scale, and a large number of cells were analyzed with the help of semiautomated cell counting. Despite considerable differences in range and distribution of Ki-67 and active caspase-3 positivity values, the model predictions showed a high degree of agreement for both markers. Comparison of 0.6 mm and 1.2 mm cores indicated that the use of small cores necessitates inclusion of a larger number of samples but requires counting a markedly smaller number of cells. Suitability of TMAs to determine the immunophenotype of the whole section was assessed using 2 different combinations of core sizes and numbers. Both displayed a high degree of concordance with the whole section ( 0.6 = 0.79; 1.2 = 0.91). The present study provides a basis for the use of TMAs in future high-throughput immunohistochemical investigations of selected markers in canine lymphomas. The statistical model presented can be used to determine an optimal TMA design depending on a desired accuracy.
Key Words: Dogs immunohistochemistry lymphoma tissue microarray (TMA) validation
A novel scheme for frequency upconversion of nanosecond optical pulses is proposed and demonstrated, yielding more than 10× bandwidth improvement and enabling the generation of broadband spectrally ...incoherent pulses in the ultraviolet.
According to an analyst report from Smith Barney, the market for managed care information systems is about $2 billion, growing to more than $5 billion by 2000. Nonetheless, these systems must prove a ...cost-effective for managed care organizations. Systems should add value and, over time, offer a return on investment. These goals are accomplished through solutions that recognize and anticipate expanding information requirements in the evolving healthcare market.
Broadband frequency conversion of nanosecond spectrally incoherent pulses from 1053 nm to 351 nm is demonstrated in a novel sum-frequency-generation noncollinear angularly dispersed scheme, yielding ...spectrally incoherent pulses with bandwidth greater than 10 THz.
We identify three regimes of correlated GeV-electron/keV-betatron-X-ray generation by a laser-plasma accelerator driven by the Texas Petawatt laser, and relate them to variations in strength of ...blowout, injection geometry and beam loading.
We present a novel way of determining the plasma temperature in a laser-cluster fusion experiment on the Texas Petawatt laser, which uses the ratio of the 2.45 MeV neutron and 14.7 MeV proton yields.
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