Author: Milton John Marcus
Publisher:
ISBN:
Category : American mink
Languages : en
Pages : 120

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Book Description

Author: Carney Landis
Publisher:
ISBN:
Category : Flicker fusion
Languages : en
Pages : 144

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Book Description

Author: Nicholas Byron Louis
Publisher:
ISBN:
Category :
Languages : en
Pages : 56

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Book Description

Author: Carney Landis
Publisher: National Academies
ISBN:
Category : Flicker fusion
Languages : en
Pages : 140

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Book Description

Author: Helga Kolb
Publisher:
ISBN:
Category :
Languages : en
Pages :

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Book Description

Author: Carol Jeanette Ladan
Publisher:
ISBN:
Category : Flicker fusion
Languages : en
Pages : 0

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Book Description
Results from a study of Thermal Flicker-Fusion (TFF) are reported. The study tested the effect of input factors similar to those significant in varying CFF (Critical Flicker-Fusion) thresholds for vision. More specifically, amount of area stimulated, intensity level and PCF (Pulse-to-Cycle Fraction) were tested separately, with other factors held constant. Thermal Flicker-Fusion (TFF) thresholds were obtained by means of intermittent radiant energy produced by a modified Hardy- Wolff-GoodeH do!orimeter. Four trained observers were employed, and were tested under all conditions replicated five times. Stimulation was applied to the two body areas (upper back and volar forearm).In general, the thermal fusion results show close correspondence to the functions produced by varying similar parameters in the visual modality. In both, curves relating sensory fusion thresholds to PCF increase to a maximum and then decline. Significant curvi1inearity is seen. Also, increases in amount of area stimulated produces a corresponding increase in both types of fusion thresholds, i.e., results show a significant linear relation between TFF and the variable of area. One major discrepancy does occur, however. In the visual modality, fusion curves produced by variation of energy level increase to a maximum and then decline. The thermal fusion curves ascend with increases in intensity, as one might expect, but no decline occurs in the range tested. Results indicate a significant linear relation between intensity and TFF. Even though "ascending" judgments were analyzed separately from "descending" judgments (due to the resulting absolute differences in rate between the two types of judgments), the form of the curves remained similar. Moreover, the form of the functions is also similar for the different body areas tested, although differences in absolute rates at fusion are noted. Results are compared to previous fusion studies in the thermal and other modalities. Decreases in inter-0_ variability were seen with increasing practice. Results of the present study were similar to those of Kastorf's investigation, in that the form of the analogous curves tended to correspond. Following this, a theoretical explanation in terms of A1ternation-of-Response theory is suggested. The significance of the thermal experiments to von Bekesy's hypothesis relating thresholds and density of innervation are briefly discussed.

Author:
Publisher:
ISBN:
Category : Optical instruments
Languages : en
Pages : 914

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Author:
Publisher:
ISBN:
Category : Medicine
Languages : en
Pages : 998

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Book Description

Author: Jeffrey Davis
Publisher: Lippincott Williams & Wilkins
ISBN: 1975143876
Category : Medical
Languages : en
Pages : 1262

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Book Description
Encompassing all occupants of aircraft and spacecraft—passengers and crew, military and civilian—Fundamentals of Aerospace Medicine, 5th Edition, addresses all medical and public health issues involved in this unique medical specialty. Comprehensive coverage includes everything from human physiology under flight conditions to the impact of the aviation industry on public health, from an increasingly mobile global populace to numerous clinical specialty considerations, including a variety of common diseases and risks emanating from the aerospace environment. This text is an invaluable reference for all students and practitioners who engage in aeromedical clinical practice, engineering, education, research, mission planning, population health, and operational support.

Author: Michael Wall
Publisher: Springer Science & Business Media
ISBN: 146138835X
Category : Medical
Languages : en
Pages : 235

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Book Description
Measurement of visual acuity has been the cornerstone of visual testing since Snellen began quantitating visual acuity using letter optotypes in the 1860s. Bjerrum in the 1880s brought sophistication and quantitation to the assessment of the visual field with tangent screen examination using differently sized and colored targets. Further advances in visual testing did not occur until the Goldmann perimeter and the Farnsworth Munsell 100 Hue test were introduced in the 1940s, permitting further refinement in the detection and quantitation of acquired visual loss. An explosion of interest in sensory visual function testing followed the demonstration by Quigley and his colleagues in 1982 that despite the loss of more than 40% of the axons in the optic nerve, Snellen acuity and kinetic perimetry remained normal. Much of this interest has focused on a search for more sensitive and disease-specific sensory visual tests. Previously, novel tests used to probe visual function remained in the province of the visual physiologist and psychophysicist. These tests are now being introduced by the ophthalmologist into clinical practice. Concomitantly, the mass production of microcomputers and other technical advances have made tests such as automated perimetry and visual evoked response testing affordable for most offices. The clinician is presently being inundated with a plethora of visual function tests that may require a knowledge of visual psychophysics and statistics to understand and interpret. The purpose of this book is to acquaint the clinician with these new tests so that they may be used to maximum benefit.