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The aim of this article was to study beat-to-beat QRS variability in patients with ischemia and old myocardial infarction using the 12-lead resting electrocardiogram (ECG). The variability analysis was based on beats that have been synchronized in time with an iterative alignment technique. The QRS variability was measured in patients submitted for myocardial scintigraphy. Those with a normal myocardial scintigraphy (called NO, n = 34, mean age 57 years, 23 women) were compared with a group with both myocardial infarction and exercise-induced ischemia (called ISCINF, n = 27, mean age 57 years, 5 women). The mean QRS variability was somewhat smaller in lead I in ISCINF than in NO, and there was no statistically significant difference in QRS variability among the groups in leads II, III, and V1-V6. Using a multivariate approach, the joint variability in leads I, II, II, and V1-V6 was used for calculating receiver operating characteristics based on a leave-one-out procedure. The sensitivity for detecting coronary artery disease was 75% at a specificity of 50%. It is concluded that beat-to-beat QRS variability in the 12-lead ECG does not discriminate between the presence and absence of coronary artery disease sufficiently well for clinical purposes. 相似文献
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The diel 'activity', i.e. availability, of Ixodes ricinus larvae, nymphs and adults was investigated in a meadow and a forest habitat near Stockholm during 1991-1993. Generally, the immature ticks were more prevalent in the forest than in the meadow. In the meadow, the mean larval and adult numbers varied significantly between 4 h time intervals with the peak activity from 2300 to 0300 h. In the forest, the tick numbers did not differ significantly between the time intervals. The association of the tick activity with certain meteorological variables was strongest in the meadow, where the mean numbers of all tick stages were negatively correlated with the temperature. The relative humidity was positively correlated only with the mean numbers of larvae. In contrast, the larval activity in the forest was positively and negatively correlated with the temperature and relative humidity, respectively, while the nymphal and adult activity showed no association with these climatic variables. The impact of the host activity on the tick diel activity is also discussed. 相似文献
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We used a safe and simple surgical technique in the management of persistent filtering cicatrices after cataract extraction. The edematous, friable filtering cicatrix was excised entirely and a healthy fornix-based conjunctival flap was sutured over the fistula. Invariably, the fistula was very small, usually only large enough to admit a 27-gauge needle. Of the 27 eyes treated with this technique, there were two failures, but no other complications. 相似文献
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J Ott 《Canadian Metallurgical Quarterly》1979,15(1):11-16
Gene-centromere distances can be estimated (i) by determining postreduction frequencies by means of ovarian teratomas and (ii) by analysis of genetic linkage between a gene locus and a structural chromosome polymorphism near the centromere. The two methods are comapred under complete interference. It is shown that the teratoma method is at least twice as efficient as the recombination method. Two estimates of the map distance for a combination of both data types are derived. 相似文献
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Determined whether a list of pairs acquired under conditions of interference is more susceptible to retroactive inhibition (RI) produced by additional interpolated interference than a list learned under noninterference conditions. The RI produced by groups differing in the type of prior learning administered, i.e., lists forming either an A-B, C-D, or an A-B, A-D relationship with the list being recalled, was compared. Results of modified-modified free recall test strongly support the susceptibility hypothesis. Data suggest (a) some evidence for proactive inhibition, but the demonstration was not reliable; and (b) that Ss who received nonspecific practice prior to their learning of 2 lists corresponding to an A-B, A-D paradigm showed less RI than Ss who had had no practice. (French summary) (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献