7435thylcyclohexane-d13 6 1.36. ,lP spectra were referenced relative to 85% H3P04 at 6 = 0. of quencher to the cuvette with a microliter syringe (Et3SiH, cyclopentene) or by employing stock solutions (PMe,, 'BuNC). In the latter case, a measured quantity of gas was condensed into a measured volume of cyclohexane on a high-vacuum line. The absorbances of the solutions for flash photolysis experiments were in the range 0.5-1.0 at 308 nm. Variable-temperature measurements were made by replacing the standard sample holder by an insulated holder mount4 on a block through which thermostat4 water was circulated.Steady-State Photolysis. Steady-state photolysis experiments were usually performed in NMR tubes in situ. NMR spectra were recorded on a Bruker MSL 300-MHz spectrometer. lH spectra were referenced to solvent peaks as follows: CLDSH 6 7.13, cyclohexane-dll 6 1.38, meAcknowledgment. We are grateful to Dr. 0. Traverso and Dr. L. D. Field for helpful discussions and for disclosing data prior to publication, to D~, s. E. J , ~~u for advice on optics, to D. ~~f i for his work in interfacing and development of software, and to Prof. and Dr. M. George for carrying Out the time-resolved IR experiment. W e acknowledge the support of The Fulbright Commission, The Royal Society, SERC, NATO, British Gas, and the E C Commission.Abstract: Trfiuoroacetic acid has been found from DTA, DSC, and temperature-dependent X-ray powder diffraction to form, besides other stable and metastable hydrates, both an undeuterated (reinvestigation) and perdeuterated stable tetrahydrate.
The total atrial conduction time (TACT) measured by echocardiography predicts the risk of atrial fibrillation (AF). This study aimed to investigate whether adding the TACT to the revised Framingham stroke risk profile (rFSRP) improves the efficacy of predicting stroke incidence in patients without prior stroke or known AF. The TACT was measured in 376 consecutive patients > 18 years (58.5 ± 16.3 years; 46% male) receiving echocardiography without any prior history of stroke or AF. The primary endpoint was the occurrence of ischemic stroke, and the secondary endpoint was any documentation of AF during the 2 years of follow-up. During the follow-up period, ischemic strokes occurred in 10 patients (2.65%), and AF in 22 patients (5.85%). The TACT was significantly longer in those who later had a stroke compared with those who did not (169.4 vs. 142.7 ms, p < 0.001). Both rFSRP and TACT predicted the risk for stroke incidence. The univariate model showed that the TACT was a predictor of ischemic stroke incidence (p < 0.001; hazard ratio of 1.94 for every 10 ms; 95% confidence interval, 1.49–2.54). The addition of TACT to rFSRP significantly improved the area under the receiver operating characteristic curve (0.79 vs. 0.85, p = 0.001). Stroke risk prediction was significantly improved by the addition of TACT to rFSRP. The utility of the TACT should be further investigated in large-scale randomized clinical trials.
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