Declines in cottonwood (Populus spp.) recruitment along alluvial reaches of large rivers in arid regions of the western United States have been attributed to modified flow regimes, lack of suitable substrate, insufficient seed rain, and increased interspecific competition. We evaluated whether and how these factors were operating during 1993–1996 to influence demographics of Fremont cottonwood ...

Thresholds for the perception of red and green or for blue and yellow, presented in two-color mixtures, were measured at exposure durations of 20, 50, 100, and 300 msec at the fovea and 6° above the fovea, at a constant luminance of 0.12 ft-L. Median foveal thresholds for red and green were constant from 300 to 50 msec and decreased slightly at 20 msec; at 6°, sensitivity to both red and green ...

His bundle electrograms were recorded in 348 patients aged 2 months to 24 years following routine diagnostic cardiac catheterization. Among 41 children found to be free of anatomic or hemodynamic abnormality the following mean values were obtained: P-H interval, 93.4 ± 15.3 msec; P-A time, 21.2 ± 7.1 msec; A-H interval, 72.2 ± 15.9 msec; and H-V interval, 39.8 ± 5.2 msec. The remaining 307 pati...

The effect of varying trials per day conditions on the CS-US interval or interstimulus interval (ISI) function in rabbit nictitating membrane response conditioning was studied in two experiments. Experiment 1 showed that a 1250-msec IS1 was more effective than a 250-msec IS1 when there was 1 trial/day. Experiment 2 showed that as the number of trials per day decreased from 20 to 1, the superior...

PURPOSE To evaluate the latency of visual evoked potentials (VEPs) in healthy women during and after menstruation. METHODS Pattern and flash VEPs were performed in 15 healthy women aged 18 to 25 years on the maximum bleeding day (luteal phase) and 7 days after the menstrual cycle (follicular phase). RESULTS Mean latency was 119.6 msec on the maximum bleeding day and 100.8 msec one week afte...

To assess the role of autonomic regulatory mechanisms on sinoatrial conduction and automaticity in patients with clinical evidence of sick sinus syndrome, electrophysiologic studies were conducted in 12 male patients, mean age 64 4 7 years. Heart rate, sinus node recovery time (SNRT) and sinoatrial conduction time (SACT) were determined before and after autonomic blockade with atropine (0.04 mg...

Purpose: To explore the usability and normal T1rho value of liver parenchyma with a novel single breathhold black blood single shot fast spin echo acquisition based liver imaging sequence. Materials and Methods: The institutional Ethics Committee approved this study. In total 19 health subjects (10 males, 9 females; mean age: 37.4 yrs; range: 23-54 yrs) participated in the study. 11 subjects ha...

Two experiments examined adult age differences in the controlled allocation of visual selective attention. Both experiments were identical with the exception of the stimulus display where targets and distractors were linearly increased with eccentricity in Experiment 2. A spatial cuing task was used with four cue-target presentation intervals (SOAs) of 250, 500, 1000, and 2000 msec (Experiment ...

Participation in natural, real-time dialogue calls for behaviors supported by perception-action cycles from around 100 msec and up. Generating certain kinds of such behaviors, namely envelope feedback, has been possible since the early 90s. Real-time backchannel feedback related to the content of a dialogue has been more difficult to achieve. In this paper we describe our progress in allowing v...

To determine the factors affecting reproducibility of sinus node recovery time, the effects of basic pacing rate, pacing duration, milliamperage, vagal and beta-adrenergic stimulation, and sinud node injury, as well as its instantaneous and daily reproducibility, were studied in 36 anesthetized dogs. Corrected sinus node recovery time (CSNRT) showed a mean variation of 9.8 plus or minus 0.4 mse...