scholarly journals INTENSITY AND CRITICAL FREQUENCY FOR VISUAL FLICKER

1937 ◽  
Vol 21 (2) ◽  
pp. 203-221 ◽  
Author(s):  
W. J. Crozier ◽  
E. Wolf ◽  
G. Zerrahn-Wolf
Keyword(s):  
Response Function ◽  
Critical Frequency ◽  
Repeated Measurements ◽  
Motor Responses ◽  
Flicker Response ◽  
Fusion Data ◽  
Quantitative Properties ◽  
Flicker Fusion ◽  
Critical Intensity

Using the rotating striped cylinder device previously employed for determination of the flicker response function with lower animals, corresponding measurements have been made with human observers. The curves based upon the relation between critical flash frequency and critical intensity for the signalling of the recognition of flicker have the properties of human flicker fusion data as obtained by other methods. They also have the quantitative properties of the flicker curves provided by the motor responses of insects and fishes to the seen movement of flashes. This applies to the variation found in repeated measurements as well as to the nature of the analytical function describing the connection between flash frequency and intensity. The data for human visual flicker and those for the responses of lower animals are therefore essentially homologous.

scholarly journals THE FLICKER RESPONSE CURVE FOR FUNDULUS

1940 ◽  
Vol 23 (6) ◽  
pp. 677-694 ◽  
Author(s):  
W. J. Crozier ◽  
Ernst Wolf
Keyword(s):  
Response Curve ◽  
Fundulus Heteroclitus ◽  
Previous Exposure ◽  
Flicker Response ◽  
Composite Form ◽  
Quantitative Properties ◽  
The Mean ◽  
Probability Integral ◽  
Critical Intensity ◽  
Observational Procedure

After Fundulus heteroclitus have been for some time in the laboratory, under conditions favorable for growth, and after habituation of the fishes to the simple routine manipulations of the observational procedure required, they are found to give reproducible values of the mean critical flash illumination (Im) resulting in response to visual flicker. The measurements were made with equality of light time and dark time in the flash cycle, at 21.5°C. Log Im as a function of flash frequency F has the same general form as that obtained with other fishes tested, and for vertebrates typically: the curve is a drawn-out S, with a second inflection at the low I end. In details, however, the curve is somewhat extreme. Its composite form is readily resolved into the two usual parts. Each of these expresses a contribution in which log I, as a function of F, is accurately expressed by taking F as the summation (integral) of a probability distribution of d log I, as for the flicker response contour of other animals. As critical intensity I increases, the contribution of rod elements gradually fades out; this decay also adheres to a probability integral. The rod contribution seen in the curve for Fundulus is larger, absolutely and relatively to that from the cones, than that found with a number of other vertebrates. The additive overlapping of the rod and cone effects therefore produces a comparatively extreme distortion of the resulting F-log I curve. The F-log Im curve is shifted to lower intensities as result of previous exposure to supranormal temperatures. This effect is only very slowly reversible. The value of Fmax. for each of the components of the duplex curve remains unaffected. The rod and cone segments are shifted to the same extent. The persisting increase of excitability thus fails to reveal any chemical or other differentiation of the excitability mechanism in the two groups of elements. Certain bearings of the data upon the theory of the flicker response contour are discussed, with reference to the measurements of variation of critical intensity and to the form of the F-log I curve. The quantitative properties of the data accord with the theory derived from earlier observations on other forms.

Hydrogeology correction in the gravitational field from satellite data

2018 ◽  
Vol 931 (1) ◽  
pp. 2-7
Author(s):  
V.D. Jushkin ◽  
L.V. Zotov ◽  
O.A. Khrapenko
Keyword(s):  
Gravitational Field ◽  
Oil And Gas ◽  
Repeated Measurements ◽  
Geological Factors ◽  
Grace Satellite ◽  
Gas Pumping ◽  
Acceleration Of Gravity ◽  
Determination Of Parameters ◽  
Gravity Acceleration

The results of repeated measurements of the acceleration of gravity by the Russian absolute ballistic field gravimeter GABL-M on points of oil and gas deposits in the permafrost over a five year period are presented. The changes of gravity acceleration by the absolute gravimeter and GRACE satellite were compared. The results of comparisons of differences gravity acceleration by ballistic gravimeter GABL-M and relative Canadian gravimeters CG5 were [i]shown. The errors in determination of parameters of the gravitational field ballistic gravimeter GABL-M and CG5 gravimeters group were presented. The method of measurement with the gravimeter GABL-M and the method of determining the vertical gradients relative CG5 gravity meters was described. The necessity of introducing corrections of hydrogeology is caused by influence of hydro geological factors on the gravitational field in the permafrost. They are comparable with the values of the field change in the result of gas pumping.

Measuring Mobility of the Metacarpophalangeal Joints II, III, IV, and V in the Dorso-Volar Plane

1984 ◽  
Vol 13 (1) ◽  
pp. 15-20 ◽  
Author(s):  
C Wagner ◽  
D Drescher
Keyword(s):  
Healthy Subjects ◽  
Reliability And Validity ◽  
Repeated Measurements ◽  
Interrater Agreement ◽  
Range Of Movement ◽  
Men And Women ◽  
Examination Method ◽  
Total Range ◽  
Flexion And Extension

An electronic gravity goniometer was developed for determining the passive range of movement of the MCP joints II, III, IV, and V in the dorso-volar plane by the use of preset torques. Test–retest measurements on 23 healthy subjects between the ages of 18 and 57 demonstrated high intrarater and interrater agreement for determining the total range. In the determination of the amounts of flexion and extension the measurement of the flexion was less reliable. There was overall evidence of a declining tendency of reliability from MCP joint II to MCP joint V, probably caused by different reactions of the joints to repeated measurements. The higher total range of the MCP joints in women was principally caused by a higher range of extension. In the case of men and women the range of MCP joint V was noticeably greater than that of the other three joints. The mobility of the four MCP joints correlates relatively closely as a whole, however, in the case of the non-adjacent joints less closely than with the adjacent joints. Reliability and validity of the examination method were balanced against one another with regard to testing of the biomechanical pre-conditions for manual dexterity.

Utilization of Multi-Axis Positioning Repeatability Performance in Kinematic Modelling

2019 ◽  
Vol 13 (1) ◽  
pp. 149-156 ◽  
Author(s):  
Károly Szipka ◽  
◽  
Andreas Archenti
Keyword(s):  
Laser Interferometer ◽  
Measurement Data ◽  
Repeated Measurements ◽  
Random Errors ◽  
Statistical Population ◽  
Measurement Results ◽  
Kinematic Modelling ◽  
Kinematic Models

Detailed description of the multi-axis repeatability performance and the modelling of non-systematic variations in the positioning performance of machine tools can support the understanding of root-causes of capability variations in manufacturing processes. Kinematic characterization is implemented through repeated measurements, which include variations related to the performance of the machine tool. This paper addresses the integration of the positional repeatability in kinematic modelling through the employment of direct measurement results. The findings of this research can be used to develop standardized approaches. The statistical population of random errors along the multi-axis travel first requires the proper management of experimental data. In this paper a methodology and its application are presented for the determination of repeatability under static and unloaded conditions as an inhomogeneous parameter in the work space. The proposed approach is demonstrated in a case study, where the component errors of a linear axis are investigated with repeated laser interferometer measurements to quantify the estimated repeatability and express it in the composed repeatability budget. The conclusions of the proposed methodology outline the sensitivity of kinematic models relying on measurement data, as the repeatability of the system can be in the same magnitude as the systematic errors.

Statistical determination of geophysical well log response functions

Geophysics ◽  
1983 ◽  
Vol 48 (11) ◽  
pp. 1525-1535 ◽  
Author(s):  
Eugene A. Nosal
Keyword(s):  
Power Spectrum ◽  
Response Function ◽  
System Response ◽  
General Terms ◽  
Induction Logging ◽  
Conductivity Profile ◽  
Statistical Determination ◽  
The One

The vertical response function of induction logging tools is shown to be derivable from a power spectrum analysis of the measurement. The vertical response function is the one‐dimensional sequence of weights that characterizes how the tool combines the rock conductivities along the borehole to form an output called the apparent conductivity; it is the system impulse response. The value of knowing this function lies in the possible use of filter theory to aid in data processing and interpretation. Two general notions establish the framework for the analysis. The first is that logging is a linear, convolutional operation. Second, the earth’s conductivity profile forms a stochastic process. The probabilistic component is fleshed out by reasonably based assumptions about the occurrence of bed boundaries and nature of conductivity changes across them. Brought together, these tenets create a characterization of the conductivity sequence that is not a stationary process, but rather is intrinsic, as defined in the discipline of geostatistics. Such a process is described by a variogram, and it is increments of the process that are stationary. The connection between the power spectrum of the measurement and the system response function is made when the convolutional model is merged with the conductivity process. Some examples of induction log functions are shown using these ideas. The analysis is presented in general terms for possibly wider application.

Sign in / Sign up

Export Citation Format

Share Document