Ultrafast time-resolved magneto-optical imaging of all-optical switching in GdFeCo with femtosecond time-resolution and a µm spatial-resolution.

We developed an ultrafast time-resolved magneto-optical (MO) imaging system with several millidegree resolution of light polarization angle, 100 fs time-resolution, and a micrometer spatial resolution. A CCD camera with about 10(6) pixels is used for detection and MO images with an absolute angle of the light polarization are acquired by the rotating analyzer method. By optimizing the analysis procedure with a least square method and the help of graphical processor units, this novel system significantly improves the speed for MO imaging, allowing to obtain a MO map of a sample within 15 s. To demonstrate the strength of the technique, we applied the method in a pump-and-probe experiment of all-optical switching in a GdFeCo sample in which we were able to detect temporal evolution of the MO images with sub-picosecond resolution.

A pilot study of cerebral tissue oxygenation and postoperative cognitive dysfunction among patients undergoing coronary artery bypass grafting randomised to surgery with or without cardiopulmonary bypass*.

Coronary artery bypass surgery, performed with or without cardiopulmonary bypass, is frequently followed by postoperative cognitive decline. Near-infrared spectroscopy is commonly used to assess cerebral tissue oxygenation, especially during cardiac surgery. Recent studies have suggested an association between cerebral desaturation and postoperative cognitive dysfunction. We therefore studied cerebral oxygen desaturation, defined as area under the cerebral oxygenation curve < 40% of > 10 min.%, with respect to cognitive performance at 4 days (early) and 3 months (late) postoperatively, compared with baseline, using a computerised cognitive test battery. We included 60 patients, of mean (SD) age 62.8 (9.4) years, scheduled for elective coronary artery bypass grafting, who were randomly allocated to surgery with or without cardiopulmonary bypass. Cerebral desaturation occurred in only three patients and there was no difference in cerebral oxygenation between the two groups at any time. Among patients who received cardiopulmonary bypass, 18 (62%) had early cognitive decline, compared with 16 (53%) in the group without cardiopulmonary bypass (p = 0.50). Three months after surgery, 11 patients (39%) in the cardiopulmonary bypass group displayed cognitive dysfunction, compared with four (14%) in the non-cardiopulmonary bypass group (p = 0.03). The use of cardiopulmonary bypass was identified as an independent risk factor for the development of late cognitive dysfunction (OR 6.4 (95% CI 1.2-33.0) p = 0.027. In conclusion, although cerebral oxygen desaturation was rare in our population, postoperative cognitive decline was common in both groups, suggesting that factors other than hypoxic neuronal injury are responsible.

Which method of estimating renal function is the best predictor of mortality after coronary artery bypass grafting?

OBJECTIVES: Definitions of renal function in patients undergoing coronary artery bypass graft surgery (CABG) vary in the literature. We sought to investigate which method of estimating renal function is the best predictor of mortality after CABG. METHODS: We analysed the preoperative and postoperative renal function data from all patients undergoing isolated CABG from January 1998 through December 2007. Preoperative and postoperative renal function was estimated using serum creatinine (SeCr) levels, creatinine clearance (CrCl) determined by the Cockcroft-Gault formula and the glomerular filtration rate (e-GFR) estimated by the Modification of Diet in Renal Disease (MDRD) formula. Receiver operator characteristic (ROC) curves and area under the ROC curves were calculated. RESULTS: In 9987 patients, CrCl had the best discriminatory power to predict early as well as late mortality, followed by e-GFR and finally SeCr. The odds ratios for preoperative parameters for early mortality were closer to 1 than those of the postoperative parameters. CONCLUSIONS: Renal function determined by the Cockcroft-Gault formula is the best predictor of early and late mortality after CABG. The relationship between renal function and mortality is non-linear. Renal function as a variable in risk scoring systems such as the EuroSCORE needs to be reconsidered.