Simultaneous and successive contrast effects of reward magnitude in selective learning.

1966 ◽  
Vol 80 (10) ◽  
pp. 1-31 ◽  
Author(s):  
Norman E. Spear ◽  
Joseph H. Spitzner
Keyword(s):  
Reward Magnitude ◽  
Contrast Effects ◽  
Selective Learning

Effects of varied preshift reward magnitude on successive negative contrast effects in rats.

1974 ◽  
Vol 86 (1) ◽  
pp. 85-95 ◽  
Author(s):  
Douglas P. Peters ◽  
James H. McHose
Keyword(s):  
Reward Magnitude ◽  
Negative Contrast ◽  
Contrast Effects ◽  
Successive Negative Contrast

scholarly journals Positive and negative successive contrast effects following multiple shifts in reward magnitude under high drive and immediate reinforcement

1976 ◽  
Vol 4 (4) ◽  
pp. 480-484 ◽  
Author(s):  
Frederick R. Maxwell ◽  
Richard S. Calef ◽  
D. W. Murray ◽  
J. C. Shepard ◽  
R. A. Norville
Keyword(s):  
Reward Magnitude ◽  
Contrast Effects ◽  
High Drive

Characteristics of simultaneous and successive contrast effects of reward magnitude

1965 ◽  
Author(s):  
Norman E. Spear ◽  
Joseph H. Spitzner
Keyword(s):  
Reward Magnitude ◽  
Contrast Effects

Shifts in magnitude of reward and contrast effects in instrumental and selective learning: A reinterpretation.

1968 ◽  
Vol 75 (2) ◽  
pp. 114-126 ◽  
Author(s):  
Roger W. Black
Keyword(s):  
Contrast Effects ◽  
Selective Learning

scholarly journals The effects of delay of reward on negative contrast effects associated with reductions in reward magnitude

1975 ◽  
Vol 6 (5) ◽  
pp. 497-500 ◽  
Author(s):  
John N. Moore ◽  
James H. McHose
Keyword(s):  
Reward Magnitude ◽  
Negative Contrast ◽  
Contrast Effects ◽  
Delay Of Reward

Observation of biological macromolecules using various electron microscopic methods

1978 ◽  
Vol 36 (2) ◽  
pp. 170-171
Author(s):  
Mitsuo Ohtsuki ◽  
Michael Sogard
Keyword(s):  
Electron Microscope ◽  
Phase Contrast ◽  
Image Interpretation ◽  
Density Lipoprotein ◽  
Biological Macromolecules ◽  
Contrast Effects ◽  
Biological Structure ◽  
Electron Microscopic ◽  
Structural Investigations ◽  
Staining Techniques

Structural investigations of biological macromolecules commonly employ CTEM with negative staining techniques. Difficulties in valid image interpretation arise, however, due to problems such as variability in thickness and degree of penetration of the staining agent, noise from the supporting film, and artifacts from defocus phase contrast effects. In order to determine the effects of these variables on biological structure, as seen by the electron microscope, negative stained macromolecules of high density lipoprotein-3 (HDL3) from human serum were analyzed with both CTEM and STEM, and results were then compared with CTEM micrographs of freeze-etched HDL3. In addition, we altered the structure of this molecule by digesting away its phospholipid component with phospholipase A2 and look for consistent changes in structure.

Analysis of STEM micrographs of thick objects

1978 ◽  
Vol 36 (2) ◽  
pp. 106-107
Author(s):  
S. Golladay
Keyword(s):  
Inelastic Scattering ◽  
Multiple Scattering ◽  
Mass Distribution ◽  
Cross Sections ◽  
Phase Contrast ◽  
Image Point ◽  
Contrast Effects ◽  
Total Cross Sections ◽  
Elastic And Inelastic Scattering

The theory of multiple scattering has been worked out by Groves and comparisons have been made between predicted and observed signals for thick specimens observed in a STEM under conditions where phase contrast effects are unimportant. Independent measurements of the collection efficiencies of the two STEM detectors, calculations of the ratio σe/σi = R, where σe, σi are the total cross sections for elastic and inelastic scattering respectively, and a model of the unknown mass distribution are needed for these comparisons. In this paper an extension of this work will be described which allows the determination of the required efficiencies, R, and the unknown mass distribution from the data without additional measurements or models. Essential to the analysis is the fact that in a STEM two or more signal measurements can be made simultaneously at each image point.

High-Voltage Scanning Electron Microscopy

1970 ◽  
Vol 28 ◽  
pp. 6-7
Author(s):  
J. M. Cowley
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Scanning Transmission Electron Microscopy ◽  
Wave Optics ◽  
Contrast Effects ◽  
Transmission Electron ◽  
Mode Of Operation ◽  
Scanning Transmission ◽  
Types Of Information ◽  
Voltage Scanning

The comparison of scanning transmission electron microscopy (STEM) with conventional transmission electron microscopy (CTEM) can best be made by means of the Reciprocity Theorem of wave optics. In Fig. 1 the intensity measured at a point A’ in the CTEM image due to emission from a point B’ in the electron source is equated to the intensity at a point of the detector, B, due to emission from a point A In the source In the STEM. On this basis it can be demonstrated that contrast effects In the two types of instrument will be similar. The reciprocity relationship can be carried further to include the Instrument design and experimental procedures required to obtain particular types of information. For any. mode of operation providing particular information with one type of microscope, the analagous type of operation giving the same information can be postulated for the other type of microscope. Then the choice between the two types of instrument depends on the practical convenience for obtaining the required Information.

Characteristic Geometry and Diffraction Contrast of Dispersed ThO2 Crystals

1969 ◽  
Vol 27 ◽  
pp. 168-169
Author(s):  
R. J. Horylev ◽  
L. E. Murr
Keyword(s):  
Dark Field ◽  
Particle Orientation ◽  
Contrast Effects ◽  
Strain Fields ◽  
Diffraction Contrast ◽  
Dispersed Particles ◽  
Field Electron Microscopy ◽  
Dark Field Electron ◽  
Particle Images ◽  
Diffraction Effects

Smith has shown by dark-field electron microscopy of extracted ThO2 particles from TD-nickel (2% ThO2) that they possess single crystal characteristics. It is generally assumed that these particle dispersions are incoherent. However, some diffraction effects associated with the particle images appeared to be similar to coherency strain fields. The present work will demonstrate conclusively that ThO2 dispersed particles in TD-nickel (2% ThO2) and TD-NiCr (2% ThO2, 20% Cr, Ni) are single crystals. Moreover, the diffraction contrast effects are extinction fringes. That is, these effects arise because of the particle orientation with respect to the electron beam and the extinction conditions for various operating reflections The particles are in fact incoherent.

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