We show that plane-wave singly resonant optical parametric oscillators exhibit a temporal modulation instability when pumped a certain number of times above threshold. Previously, this instability threshold was predicted, with a model neglecting variations in pump power, to occur at around 4.61 times oscillation threshold. We consider here the full self-consistent interaction between pump, sign...

Motor control neuroscientists measure limb trajectories and extract the onset of the movement for a variety of purposes. Such trajectories are often aligned relative to the onset of individual movement before the features of that movement are extracted and their properties are inspected. Onset detection is performed either manually or automatically, typically by selecting a velocity threshold. ...

In this study, we examined the collision avoidance behavior of the frog, Rana catesbeiana to an approaching object in the upper visual field. The angular velocity of the frog's escape turn showed a significant positive correlation with the turn angle (r(2) = 0.5741, P<0.05). A similar mechanism of velocity control has been known in head movements of the owl and in human saccades. By analogy, th...

Motor control neuroscientists measure limb trajectories and extract the onset of the movement for a variety of purposes. Such trajectories are often aligned relative to the onset of individual movement before the features of that movement are extracted and their properties are inspected. Onset detection is performed either manually or automatically, typically by selecting a velocity threshold. ...

Standing subjects were unexpectedly pulled forward to identify a threshold boundary that evokes stepping in terms of the size of the pull relative to the base of support (BoS). Performances in a range of sensorimotor tests were correlated with the threshold boundary parameters. Younger and older subjects were studied to identify age-related changes in stepping and the threshold boundaries. The ...

This study examined the effects of unexpected loading on muscle activation during fast goal-oriented movements. We tested the hypothesis that the electromyographic (EMG) response to an unexpected load occurs at a short latency after the difference between the expected and the unexpected movement velocity exceeds a fixed threshold. Subjects performed two movement tasks as follows: 1) 30 degrees ...

Background. While flow convergence methods have been promising for calculating volume flows from color Doppler images, it appears that the velocity threshold used and the transorifice pressure gradient dramatically influence the accuracy of application of the simple hemispheric flow convergence equation for calculation of flow rate. The present in vitro study was performed to determine whether ...

The physiological properties of the ovipositor hair sensilla of the desert locust and their responses to wind and to direct mechanical displacement are described. The hairs on the external surfaces of the ventral and dorsal ovipositor valves respond to wind stimulation, whereas the hairs on the inner surfaces of the dorsal valves are not wind-sensitive. All ovipositor hairs, however, respond to...

BACKGROUND While flow convergence methods have been promising for calculating volume flows from color Doppler images, it appears that the velocity threshold used and the transorifice pressure gradient dramatically influence the accuracy of application of the simple hemispheric flow convergence equation for calculation of flow rate. The present in vitro study was performed to determine whether t...