Choice alternation: III. Response intensity vs. response discriminability.

1955 ◽  
Vol 48 (2) ◽  
pp. 80-85 ◽  
Author(s):  
E. L. Walker ◽  
W. N. Dember ◽  
R. W. Earl ◽  
C. L. Fawl ◽  
A. J. Karoly
1996 ◽  
Vol 26 (6) ◽  
pp. 967-972 ◽  
Author(s):  
René I. Alfaro ◽  
G.K. Kiss ◽  
A. Yanchuk

The intensity of the traumatic resin response in white spruce, Piceaglauca (Moench) Voss, to attack by the white pine weevil, Pissodesstrobi Peck, was studied in trees with different severities of attack. The response level was highest in trees where the attacks failed, i.e., where eggs were laid but the brood was killed and no adults emerged. Successfully attacked trees had, on average, only 62% of the response intensity of trees with failed attacks. Response intensity in trees that had been subjected only to feeding was much lower, at 42% of the failed attack response. Healthy unattacked trees showed no or little traumatic resin response. Response intensity varied in a nonlinear fashion with the number of eggs laid, increasing rapidly from zero in healthy trees, being highest in trees having between 10 and 60 egg punctures, and progressively lower again in trees with higher numbers of egg punctures. For a given number of egg punctures, resistant white spruce trees had a consistently higher traumatic resin response than susceptible trees. The number of eggs laid on a leader was inversely related to the intensity of the traumatic resin response and to the timing of the attack. Fewer eggs were laid on leaders with high traumatic resin response or attacked late in the season than on leaders with lower resin response or attacked early in the season.


2000 ◽  
Vol 83 (3) ◽  
pp. 1224-1242 ◽  
Author(s):  
Alan M. Brichta ◽  
Jay M. Goldberg

Multivariate statistical formulas were used to infer the morphological type and longitudinal position of extracellularly recorded afferents. Efferent fibers were stimulated electrically in the nerve branch interconnecting the anterior and posterior VIIIth nerves. Responses of bouton (B) units depended on their inferred position: BP units (near the planum semilunatum) showed small excitatory responses; BT units (near the torus) were inhibited; BM units (in an intermediate position) had a mixed response, including an initial inhibition and a delayed excitation. Calyx-bearing (CD-high) units with an appreciable background discharge showed large per-train excitatory responses followed by smaller post-train responses that could outlast the shock train by 100 s. Excitatory responses were smaller in calyx-bearing (CD-low) units having little or no background activity than in CD-high units. Excitatory response-intensity functions, derived from the discharge during 2-s angular-velocity ramps varying in intensity, were fit by empirical functions that gave estimates of the maximal response ( r MAX), a threshold velocity ( v T), and the velocity producing a half-maximal response ( v 1/2). Linear gain is equal to r MAX/ v S, v S = v 1/2 − v T. v S provides a measure of the velocity range over which the response is nearly linear. For B units, r MAX declines by as much as twofold over the 2-s ramp, whereas for CD units, r MAXincreases by 15% during the same time period. At the end of the ramp, r MAX is on average twice as high in CD as in B units. Thresholds are negligible in most spontaneously active units, including almost all B and CD-high units. Silent CD-low units typically have thresholds of 10–100 deg/s. BT units have very high linear gains and v S < 10 deg/s. Linear gains are considerably lower in BP units and v S> 150 deg/s. CD-high units have intermediate gains and near 100 deg/s v S values. CD-low units have low gains and v S values ranging from 150 to more than 300 deg/s. The results suggest that BT units are designed to measure the small head movements involved in postural control, whereas BP and CD units are more appropriate for monitoring large volitional head movements. The former units are silenced by efferent activation, whereas the latter units are excited. This suggests that the efferent system switches the turtle posterior crista from a “postural” to a “volitional” mode.


2011 ◽  
Vol 227 ◽  
pp. 39-42
Author(s):  
Samira Kaci ◽  
Aissa Keffous ◽  
Mohamed Trari ◽  
Brahim Mahmoudi ◽  
Hamid Menari

In this work, we have employed chemical bath deposition (CBD) method to obtain nanocrystalline PbS thin films in the presence of polyethylene oxide (PEO). The spectral response of Au/PbS-pSi(100)/Al Schottky photodiodes at different PEO amount were studied. The response exhibits a combined effect of photogeneration in the heterojunction (HJ) Si side and PbS. Spectral response were observed progressively at shorter wavelength due to the surface absorption. The peak centered at 410 nm properly corresponds to photo-exited holes being injected from PbS to the Si substrate. The intensity of the peak of R(λ) increases with PEO amount, this increasing was attributed to the decreasing of band gap (Eg).


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