Pigeon performance on a variable-interval omission schedule at different levels of food deprivation

1992 ◽  
Vol 27 (1) ◽  
pp. 27-35 ◽  
Author(s):  
Paul Lewis ◽  
Donald M. Dougherty
Keyword(s):  
Food Deprivation ◽  
Variable Interval ◽  
Different Levels

Sucrose Concentration as Reinforcement for Lever Pressing by Monkeys

1956 ◽  
Vol 2 (3) ◽  
pp. 381-384 ◽  
Author(s):  
Donald G. Conrad ◽  
Murray Sidman
Keyword(s):  
Food Deprivation ◽  
Rhesus Monkeys ◽  
Response Rate ◽  
Sucrose Concentration ◽  
Variable Interval ◽  
Variable Interval Schedule ◽  
Interval Schedule ◽  
Satiation Effect ◽  
Low Concentrations ◽  
Lever Pressing

3 rhesus monkeys were given various concentrations of sucrose for lever pressing on a variable interval schedule of reinforcement. 7 sucrose concentrations were studied at 2 levels of food deprivation. The response rates accelerated rapidly with increasing concentrations, and then declined after reaching a maximum, generally between 15 and 30% sucrose concentration. The decline was attributed to a satiation effect. The higher level of food deprivation tended to increase the response rate at all but the extreme high and low concentrations.

Concurrent Food- and Water-Reinforced Responding under Food, Water, and Food-Plus-Water Deprivation

1965 ◽  
Vol 16 (3_suppl) ◽  
pp. 1305-1311 ◽  
Author(s):  
Daniel Fallon ◽  
Donald M. Thompson ◽  
Mary E. Schild
Keyword(s):  
Food Deprivation ◽  
Water Deprivation ◽  
Food Reinforcement ◽  
Variable Interval ◽  
Variable Interval Schedule ◽  
Deprivation Condition ◽  
Experimental Chamber ◽  
Water Reinforcement ◽  
Interval Schedule

The effect of 22-hr. food, water, and food-plus-water deprivation cycles upon the bar-pressing performance of rats was assessed. In a two-bar experimental chamber, one bar produced intermittent food and another intermittent water reinforcement. Each food reinforcement was approximately equivalent by weight to each water reinforcement, and both bars were concurrently operative on a variable-interval schedule. During the first and last 6 of 18 successive 2-hr. sessions under each deprivation condition, most responses were emitted under food deprivation, next most under food-plus-water deprivation, and least under water deprivation. Rate of responding for food was consistently higher than for water.

Dependence of Intergranular Fracture on Boundary Topography and Cohesion

1973 ◽  
Vol 31 ◽  
pp. 150-151
Author(s):  
J. E. Doherty ◽  
A. F. Giamei ◽  
B. H. Kear ◽  
C. W. Steinke
Keyword(s):  
Grain Boundary ◽  
Room Temperature ◽  
Nickel Base Superalloy ◽  
Boundary Shear ◽  
Room Temperature Ductility ◽  
Solid Solution Matrix ◽  
Nickel Base ◽  
Solution Matrix ◽  
Different Levels ◽  
Base Superalloy

Recently we have been investigating a class of nickel-base superalloys which possess substantial room temperature ductility. This improvement in ductility is directly related to improvements in grain boundary strength due to increased boundary cohesion through control of detrimental impurities and improved boundary shear strength by controlled grain boundary micros true tures.For these investigations an experimental nickel-base superalloy was doped with different levels of sulphur impurity. The micros tructure after a heat treatment of 1360°C for 2 hr, 1200°C for 16 hr consists of coherent precipitates of γ’ Ni3(Al,X) in a nickel solid solution matrix.

Immunoenzymatic demonstration of the simultaneous presence of transferrin, hemopexin and albumin in a same hepatocyte and their ultrastructural localization

1978 ◽  
Vol 36 (2) ◽  
pp. 88-89
Author(s):  
M. Kraemer ◽  
J. Foucrier ◽  
J. Vassy ◽  
M.T. Chalumeau
Keyword(s):  
Plasma Proteins ◽  
Rat Hepatocytes ◽  
Ultrastructural Localization ◽  
Carrier Proteins ◽  
Normal Cells ◽  
Adult Rat ◽  
Adult Rat Hepatocytes ◽  
Monospecific Antisera ◽  
Different Levels

Some authors using immunofluorescent techniques had already suggested that some hepatocytes are able to synthetize several plasma proteins. In vitro studies on normal cells or on cells issued of murine hepatomas raise the same conclusion. These works could be indications of an hepatocyte functionnal non-specialization, meanwhile the authors never give direct topographic proofs suitable with this hypothesis.The use of immunoenzymatic techniques after obtention of monospecific antisera had seemed to us useful to bring forward a better knowledge of this problem. We have studied three carrier proteins (transferrin = Tf, hemopexin = Hx, albumin = Alb) operating at different levels in iron metabolism by demonstrating and localizing the adult rat hepatocytes involved in their synthesis.Immunological, histological and ultrastructural methods have been described in a previous work.

The Effects of Variable-Interval and Fixed-Interval Signal Presentation Schedules on the Auditory Evoked Response

1969 ◽  
Vol 12 (1) ◽  
pp. 199-209 ◽  
Author(s):  
David A. Nelson ◽  
Frank M. Lassman ◽  
Richard L. Hoel
Keyword(s):  
Variable Interval ◽  
Tone Burst ◽  
Signal Amplitude ◽  
Fixed Interval ◽  
Interval Schedule ◽  
Sensation Level ◽  
Fixed Interval Schedule ◽  
Auditory Evoked Responses ◽  
Auditory Evoked Response ◽  
Signal Presentation

Averaged auditory evoked responses to 1000-Hz 20-msec tone bursts were obtained from normal-hearing adults under two different intersignal interval schedules: (1) a fixed-interval schedule with 2-sec intersignal intervals, and (2) a variable-interval schedule of intersignal intervals ranging randomly from 1.0 sec to 4.5 sec with a mean of 2 sec. Peak-to-peak amplitudes (N 1 — P 2 ) as well as latencies of components P 1 , N 1 , P 2 , and N 2 were compared under the two different conditions of intersignal interval. No consistent or significant differences between variable- and fixed-interval schedules were found in the averaged responses to signals of either 20 dB SL or 50 dB SL. Neither were there significant schedule differences when 35 or 70 epochs were averaged per response. There were, however, significant effects due to signal amplitude and to the number of epochs averaged per response. Response amplitude increased and response latency decreased with sensation level of the tone burst.

Memory Processes, Aging, Cognitive Decline, and Neurodegenerative Diseases

2006 ◽  
Vol 11 (4) ◽  
pp. 304-311 ◽  
Author(s):  
Lars-Göran Nilsson
Keyword(s):  
Cognitive Impairment ◽  
Cognitive Decline ◽  
Neurodegenerative Disease ◽  
Genetic Markers ◽  
Brain Activity ◽  
Memory Performance ◽  
Modeling And Simulations ◽  
Aging And Health ◽  
Explained Variance ◽  
Different Levels

This paper presents four domains of markers that have been found to predict later cognitive impairment and neurodegenerative disease. These four domains are (1) data patterns of memory performance, (2) cardiovascular factors, (3) genetic markers, and (4) brain activity. The critical features of each domain are illustrated with data from the longitudinal Betula Study on memory, aging, and health ( Nilsson et al., 1997 ; Nilsson et al., 2004 ). Up to now, early signs regarding these domains have been examined one by one and it has been found that they are associated with later cognitive impairment and neurodegenerative disease. However, it was also found that each marker accounts for only a very small part of the total variance, implying that single markers should not be used as predictors for cognitive decline or neurodegenerative disease. It is discussed whether modeling and simulations should be used as tools to combine markers at different levels to increase the amount of explained variance.

Implications of Person Fluctuation for the Stability and Validity of Test Scores

Methodology ◽  
2006 ◽  
Vol 2 (4) ◽  
pp. 142-148 ◽  
Author(s):  
Pere J. Ferrando
Keyword(s):  
Item Response ◽  
Test Scores ◽  
Temporal Stability ◽  
Person Fit ◽  
Item Parameters ◽  
Individual Trait ◽  
The Stability ◽  
The Individual ◽  
Different Levels ◽  
Fluctuation Model

In the IRT person-fluctuation model, the individual trait levels fluctuate within a single test administration whereas the items have fixed locations. This article studies the relations between the person and item parameters of this model and two central properties of item and test scores: temporal stability and external validity. For temporal stability, formulas are derived for predicting and interpreting item response changes in a test-retest situation on the basis of the individual fluctuations. As for validity, formulas are derived for obtaining disattenuated estimates and for predicting changes in validity in groups with different levels of fluctuation. These latter formulas are related to previous research in the person-fit domain. The results obtained and the relations discussed are illustrated with an empirical example.

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