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H Eisler

Publications and source records attributed to H Eisler.

13 recordsLinked to original sources
PubMed2000

Optical gain and stimulated emission in nanocrystal quantum dots.

The development of optical gain in chemically synthesized semiconductor nanoparticles (nanocrystal quantum dots) has been intensely studied as the first step toward nanocrystal quantum dot lasers. We examined the competing dynamical processes involved in optical amplification and lasing in nanocrystal quantum dots and found that, despite a highly efficient intrinsic nonradiative Auger recombination, large optical gain can be developed at the wavelength of the emitting transition for close-packed solids of these dots. Narrowband stimulated emission with a pronounced gain threshold at wavelengths tunable with the size of the nanocrystal was observed, as expected from quantum confinement effects. These results unambiguously demonstrate the feasibility of nanocrystal quantum dot lasers.

Journal Article↗
PubMed1992

Time perception: effects of sex and sound intensity on scales of subjective duration.

Six women and six men reproduced ten time intervals varying in logarithmic steps between 1.3 and 20 s. The durations were indicated by white noise of 10, 25, 40 and 55 dB SL, different sound intensities in different sessions. It was found that (i) greater sound intensity entails shorter reproductions, and (ii) reproductions by male observers are shorter than those by female, although for both (i) and (ii) there is an interaction with the standard durations. The data were treated in accordance with the "parallel-clock model" (Eisler, 1975), whereby the parameters of the psychophysical power function are determined from duration reproduction data. As in previous experiments (Eisler, 1975), the data showed a break in the function entailing two segments. The effect of sound intensity could be attributed to the exponent, which was lower for stronger noise, and the effect of sex to the weight coefficient of the upper relative to the lower segment of the psychophysical function, the coefficient being lower for men.

Adult↗
PubMed1984

Knowing before doing: discrimination by rats of a brief interruption of a tone.

Eight rats' lever presses were reinforced after an interruption in a tone, provided the lever had not been pressed before the tone interruption. After a few sessions, long before the animals reliably refrained from lever pressing before the interruption, the latencies of postinterruption presses (time from the termination of the interruption to the moment of the lever press) dissociated into two classes: short ones for to-be-rewarded presses, and long ones for presses in the other trials, which contained no reward because one or more lever presses had occurred before the interruption. Thus discrimination of impending reinforcement in the current trial occurred before there was evidence of sensitivity to reinforcement in the reinforcement-producing aspect of behavior. This finding is related to Shimp's (1981) contention that the temporal properties of recent behavior are reinforceable, if remembered. The present finding shows that learning to discriminate whether one's behavior has met a contingency, and learning to carry out this behavior, need not go together, implying that memory of temporal properties is probably a necessary but not a sufficient condition for learning the latter.

Animals↗
PubMed1984

Comments on Shimp's (1983) double dissociation between knowledge and tacit knowledge.

Shimp (1983) found in five pigeons "double dissociation" between the distribution of pairs of long and short reinforced interresponse times and "self-reports," obtained by symbolic matching to sample, concerning these interresponse times. This result can be explained by assuming that the birds used a fixed temporal interval as matching criterion, independently of which pattern of interresponse times was reinforced.

Journal Article↗
PubMedDate not supplied

A mathematical model for time perception with experimentally obtained subjective time scales for humans and rats.

The concept of sensation measurement with the entailing subjective scales is explained. It is shown that linearity between, e.g. sensation halving values and standard values implies that subjective sensation (output) grows as a power function of the physical measure of the stimulus (input). This outcome can be used in the scaling of subjective duration, based on reproduction experiments, i.e., experiments in which the participants are required to reproduce given time intervals, e.g., indicated by noise. It will be shown that what is reproduction for the participant is halving for the experimenter, making it possible to determine the parameters of the power function. The model is confirmed experimentally for humans and rats, the rats having a lower exponent than adults. In a recent experiment it was shown that the reproduced durations differ between female and male observers as well as for different sound intensities. These differences could be attributed to differences in parameter values. An interesting observation is that almost all power functions exhibit a discontinuity, possibly indicating a switch between different neural loops as the durations become longer.

Animals↗
PubMedDate not supplied

Subjective time scaling: influence of age, gender, and Type A and Type B behavior.

Forty-eight subjects, divided into 4 equal groups (young and older female, young and older male), reproduced 19 time intervals varying in logarithmic steps between 1.3 and 20 s. The durations were indicated by noise of 50 dB SL. To assess Type A and Type B behavior, the subjects were administered a Swedish version of Jenkins Activity Survey with 21 items. It was found that 1. reproductions of durations by older subjects are longer than those by younger subjects, and 2. reproductions by male subjects are shorter than those by female, although an interaction was also detected between gender and the standard durations. Type A and Type B behavior did not show any main effect. The data were treated in accordance with the "parallel-clock model", whereby the parameters of the psychophysical power function are determined from duration reproduction data. As in previous experiments, the data showed a break in the function, entailing two segments. The effect of both age and gender could be explained by the weight coefficient of the upper relative to the lower segment of the psychophysical function, the coefficient being lower for male and higher for older subjects.

Acoustic Stimulation↗