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Biomedical subjects

B C Jiang

Publications and source records attributed to B C Jiang.

26 records · Page 2Linked to original sources
PubMed1988

Steady state of accommodation during observation of a Scheiner image.

To evaluate the observer's ability to self-monitor and correct accommodation voluntarily, a slit aperture, incorporating the Scheiner principle, was used as an accommodative stimulus. The Scheiner image consisted of two horizontal lines, which were perceived as superimposed into a single line when the observer's accommodation was conjugate with the optical distance of the target. The observer's task was to maintain superimposition of the monocularly viewed lines. During the task, accommodation was assessed with a Badal optometer that incorporated gratings of several spatial frequencies. By varying the optical distance of these gratings it was possible to determine the location of minimum blur, and thus the accommodation response. Results from two observers indicated that a Scheiner image can be used effectively for voluntary adjustments in accommodation for several optical distances.

Accommodation, Ocular↗
PubMed1987

Establishing a physical criterion for assigning personnel to U.S. Air Force jobs.

The Air Force has had problems with personnel being physically unable to perform the tasks within their assigned Air Force Specialty Code (AFSC). An assignment criterion was developed based on a single isoinertial strength score (X1): the incremental 1.83 m lift. The job assignment criterion was developed through three phases of work: Phase I analyzed AFSC tasks; Phase II developed strength/stamina tests; and Phase III established the assignment criteria.

Adult↗
PubMed1984

A manual materials handling study of bag lifting.

Physiological and psychophysical research approaches were employed to determine the effects of two levels of fullness (70% and 95%) and the use of handles on bag lifting tasks. A comparison of bag lifting and box lifting was also conducted. Neither the level of bag fullness nor the availability of handles on the bag resulted in a significant change in physiological response for a 20.4 kg load. The maximum acceptable weight lifted was significantly higher when performing a bag lifting task either with handles or when the bag was 95% full. The maximum acceptable weight of lift for bag lifting tasks was higher (2.21 kg) than for box lifting tasks under the conditions of this experiment.

Adolescent↗
PubMed1984

Contrast sensitivity measured during smooth pursuit movement.

When pursuit eye movement is guided by a light spot which moves at the same velocity as that of a drifting grating, the reciprocal of the threshold contrast (TC) needed for the eye to perceive the grating moving at the same velocity as the auxiliary spot is defined as the guided pursuit contrast sensitivity (GP-CS). GP-CS and flicker (F-) or motion-CS are determined for 20-21 out of 25 possible combinations of 0.75, 1.5, 3, 6 and 12 c/deg grating drifting at 1, 2, 4, 8 or 16 Hz. Up to a drifting velocity of about 5 degrees/s, the GP-CS is near to the pattern recognition (PR)-CS for a stationary grating (+20 to -40%), while the F-CS shows systematic higher (100-200%) to lower (30-60%) values than the PR-CS from low to high spatial frequency (SF) gratings as found by previous investigators. These differences can be most easily seen when the GP-CSF's for gratings drifting at 2, 4 and 8 Hz are plotted and compared with the respective F-CSF's against SF. The general shape of the GP-CSF's shows remarkable similarity to that of PR-CSF at 0 Hz which is generally regarded to be mediated by the so-called sustained system. Apparent motion sensation is inevitably associated with GP. Participation of sustained system in the mediation of motion sensation and the implication of pattern vision during smooth pursuit eye movement are discussed.

Eye Movements↗
PubMed1982

Use of annular artificial pupil in the determination of modulation transfer function of the eye.

According to Ref. [1] primary spherical aberration of the schematic eye would be completely absorbed by an annular aperture when its obstruction ratio epsilon is greater than or equal to 0.60. Consequently the contrast sensitivity function, Tcs, determined with the use of such an annulus, Tcs (A), is the MTF of the retina-brain system, Trb, weighted by the MTF of the annulus, T. . Trb thus obtained can be used to determine the MTF of the eye, Te. Annular apertures of various sizes and obstruction ratios used for the determination of Te have been analysed. It is shown that there are several factors other than incomplete absorption of primary spherical aberration that would prevent the use of annular pupil to derive Trb under unrestrained conditions. This is due to the fact that the apparent T.'s of annuli used in the actual determination of Tcs(A) usually deviate from the theoretical T.'s for the passive eye to different extents. However, it is found that the T. for annulus of o.d. = 2.7 mm and epsilon = 0.60 conforms more or less to the theoretical T. and can be used to derive reasonably accurate Te(2.7). It is also possible to estimate Te(less than 2.7) from Te(2.7) by some empirical correction.

Adaptation, Ocular↗