Biomedical subjects

J B Spiegler

Publications and source records attributed to J B Spiegler.

6 recordsLinked to original sources

PubMed1986

Apparent path of a Pulfrich target as a function of the slope of its plane of motion: a theoretical note.

A theoretical equation is derived to predict the apparent path of a Pulfrich target moving with constant velocity in a plane that intersects the pupillary plane of an observer. Generally, the predicted apparent path is a hyperbola. However, if the angle between the two planes is zero, or they intersect at a pupillary center, then the predicted apparent path is a line. Other theoretical equations are derived that describe the apparent size and orientation of a line target that is parallel to the pupillary plane and receding from the observer.

Depth Perception↗

PubMed1982

Lens weight as a function of density, shape, and power.

An equation to determine the weight of a spherical lens as a function of its density, shape, and power is presented. I found that if center thickness and size are held constant, lens weight increases as the lens power increases in minus or decreases in plus. A way to calculate the power at which two lenses are equal in weight when they differ only in density is also presented. This power is the endpoint of a range of powers above which one of the two lenses is heavier, whereas below this power it is lighter than the other lens. A way to reduce the weight of a lens by altering the surface powers is also suggested.

Eyeglasses↗

PubMed1980

Matrix techniques in colorimetry.

The usual (geometric) procedure to determine the chromaticity coordinates of a color that results from the additive mixture of colored stimuli is to plot the coordinates of these stimuli on the CIE chromaticity diagram and apply the center-of-gravity rule. This procedure, however, may become inaccurate and cumbersome if more than just a few colored stimuli are mixed in various proportions. An alternate method is presented that uses matrix techniques to solve problems related to colorimetry simply and accurately.

Color↗

PubMed1980

The observed image velocity of a stationary target reflected by a rotating plane mirror.

An equation is presented describing the angular velocity of an image, viewed by an observer when a plane mirror is undergoing angular velocity. The image velocity is determined at the observer's entrance pupil. An expression to determine the size of the mirror aperture for a given exposure time is also presented. The results indicate that, in general, the image velocity is not constant nor twice the mirror velocity, as is usually assumed. Also, if the mirror extends to an equal length on each side of its axis of rotation, then the time in which the image appears to travel from the mirror's edge to the axis of rotation does not equal the time in which it appears to travel from the axis to the other edge.

Humans↗

PubMed1974

Independence of location of light absorption and discrete wave latency distribution in Limulus ventral nerve photoreceptors.

Discrete waves of depolarization evoked by dim pulses of light in dark-adapted ventral nerve photoreceptors in Limulus show fluctuation in their latency. To a resolution of 5-10 microm the latency distribution function appears to be independent of where in the receptor light is absorbed. Also, there is apparent local adaptation to bright light pulses.

Adaptation, Ocular↗

PubMed1973

Light-evoked and spontaneous discrete waves in the ventral nerve photoreceptor of Limulus.

Discrete waves, recorded from the ventral nerve photoreceptor, occur in the light and in the dark. Spontaneous waves, on the average, are smaller than light-evoked waves. This suggests that not all spontaneous waves can arise from spontaneous changes in the visual pigment molecule identical to changes induced by photon absorption. Spontaneous and light-evoked waves are statistically independent of each other. This is shown by determination of frequency of response as a function of pulse energy for short pulses and determination of the distribution of intervals between waves evoked by steady lights. The available data can be explained by two models. In the first each photon produces a time-dependent excitation that goes to zero the instant the wave occurs so that the number of effective absorptions from a short light pulse equals the number of waves produced by the light pulse. In the second the excitation produced by photon absorption is unaffected by the occurrence of the waves so that the number of waves produced from a short light pulse may be different from the number of effective absorptions. Present results do not allow a choice between the two models.

Animals↗