Evaluation of the performance of two new generation pulse oximeters in cats at different probe positions and under the influence of vasoconstriction

Objectives The aim of this study was to compare the failure rate of two new generation pulse oximeters at different probe positions, and with and without vasoconstriction, in anaesthetised cats. Methods This prospective clinical study included 103 cats in which the new generation pulse oximeters, the Rad-5 (Masimo) and EDAN H100N (EDAN), were evaluated. Premedication consisted of the vasoconstrictive drug combination butorphanol (0.2 mg/kg IV) and dexmedetomidine (5 µg/kg IV), or butorphanol only (0.2 mg/kg IV). Pulse oximeter failure rate at the tongue was compared between both groups. Pulse oximeter failure rate was also analysed at the alternative probe positions of the lip, pinna, knee fold and toe in the butorphanol group. Student’s t-test, Wilcoxon matched pairs signed rank test, Mann−Whitney U-test, Friedman test and χ2 test were performed. A P value <0.05 was considered to be statistically significant. Results Overall failure to achieve an adequate signal was 37.6% with the Masimo and 48.0% with the EDAN pulse oximeter ( P <0.0001). At the standard probe position on the tongue, the Masimo failed in 4.5%, while the EDAN failed in 35.3% ( P <0.0001). Vasoactive premedication increased the failure rate for the Masimo from 3.8% to 5.2% ( P = 0.3414) and for the EDAN from 22.4% to 49.0% ( P <0.0001). At the alternative probe positions of the lip and knee fold, failure rates for the Masimo were lower (39.7% and 81.4%) than with the EDAN (52.6% and 94.4%; P = 0.0231 and P = 0.0005, respectively), while the Masimo failed more often at the pinna (63.5%) than the EDAN (47.4%; P = 0.0044). At the alternative probe position of the toe, the failure rate for the Masimo (32.7%) was not different from the EDAN (38.5%; P = 0.7547). Conclusions and relevance The Masimo pulse oximeter had lower signal failure rates at the standard probe position on the tongue and at 2/4 alternative probe positions. The standard probe position on the tongue had the lowest failure rate for both devices. Dexmedetomidine-induced vasoconstriction increased the failure rate for the EDAN but not for the Masimo pulse oximeter.

The all-diode-pumped laser system POLARIS – an experimentalist’s tool generating ultra-high contrast pulses with high energy

The development, the underlying technology and the current status of the fully diode-pumped solid-state laser system POLARIS is reviewed. Currently, the POLARIS system delivers 4 J energy, 144 fs long laser pulses with an ultra-high temporal contrast of $\def \xmlpi #1{}\def \mathsfbi #1{\boldsymbol {\mathsf {#1}}}\let \le =\leqslant \let \leq =\leqslant \let \ge =\geqslant \let \geq =\geqslant \def \Pr {\mathit {Pr}}\def \Fr {\mathit {Fr}}\def \Rey {\mathit {Re}}5\times 10^{12}$ for the ASE, which is achieved using a so-called double chirped-pulse amplification scheme and cross-polarized wave generation pulse cleaning. By tightly focusing, the peak intensity exceeds $3.5\times 10^{20}\ \mathrm{W\ cm}^{-2}$ . These parameters predestine POLARIS as a scientific tool well suited for sophisticated experiments, as exemplified by presenting measurements of accelerated proton energies. Recently, an additional amplifier has been added to the laser chain. In the ramp-up phase, pulses from this amplifier are not yet compressed and have not yet reached the anticipated energy. Nevertheless, an output energy of $16.6\ \mathrm{J}$ has been achieved so far.

A New Method of Parameters Determined in PCNN

The aim of this paper is to research the image recognition system and its applications, which is based on combining the traditional BP neural networks and the third-generation pulse coupled neural network (PCNN).The process is by extracting the image's time and entropy sequences, then through the fast Fourier transform, and finally as inputs of the pattern classification. In order to test the stability of the system, we make some varies by rotating, tension and compressing the original image, meanwhile, combined with the statistics of the entropy information to determine the time delay parameter of the pcnn, the recognition results is satisfactory.