| Records |
| Author |
Hagen, S.J.; Eaton, W.A. |
Title  |
Two-state expansion and collapse of a polypeptide |
Type |
Journal Article |
| Year |
2000 |
Publication |
Journal of Molecular Biology |
Abbreviated Journal |
J Mol Biol |
| Volume |
301 |
Issue |
4 |
Pages |
1019-1027 |
| Keywords |
Animals; Computer Simulation; Cytochrome c Group/*chemistry/*metabolism; Horses; Kinetics; Lasers; Models, Chemical; Peptides/*chemistry/*metabolism; Protein Conformation; Protein Denaturation; *Protein Folding; Spectrometry, Fluorescence; Temperature; Thermodynamics |
| Abstract |
The initial phase of folding for many proteins is presumed to be the collapse of the polypeptide chain from expanded to compact, but still denatured, conformations. Theory and simulations suggest that this collapse may be a two-state transition, characterized by barrier-crossing kinetics, while the collapse of homopolymers is continuous and multi-phasic. We have used a laser temperature-jump with fluorescence spectroscopy to measure the complete time-course of the collapse of denatured cytochrome c with nanosecond time resolution. We find the process to be exponential in time and thermally activated, with an apparent activation energy approximately 9 k(B)T (after correction for solvent viscosity). These results indicate that polypeptide collapse is kinetically a two-state transition. Because of the observed free energy barrier, the time scale of polypeptide collapse is dramatically slower than is predicted by Langevin models for homopolymer collapse. |
| Address |
Laboratory of Chemical Physics, NIDDK, National Institutes of Health, Building 5, Bethesda, MD, 20892-0520, USA |
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English |
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| ISSN |
0022-2836 |
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| Notes |
PMID:10966803 |
Approved |
no |
| Call Number |
Equine Behaviour @ team @ |
Serial |
3790 |
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| Author |
Westergaard, G.C.; Liv, C.; Rocca, A.M.; Cleveland, A.; Suomi, S.J. |
| Title |
Tufted capuchins (Cebus apella) attribute value to foods and tools during voluntary exchanges with humans |
Type |
Journal Article |
| Year |
2004 |
Publication |
Animal Cognition |
Abbreviated Journal |
Anim. Cogn. |
| Volume |
7 |
Issue |
1 |
Pages |
19-24 |
| Keywords |
Animals; Cebus/*physiology; *Food; Humans; *Object Attachment; *Social Behavior |
| Abstract |
This research examined exchange and value attribution in tufted capuchin monkeys ( Cebus apella). We presented subjects with opportunities to obtain various foods and a tool from an experimenter in exchange for the foods or tool in the subjects' possession. The times elapsed before the first chow biscuits were expelled and/or an exchange took place were recorded as the dependent measures. Laboratory chow biscuits, grapes, apples, and a metal bolt (a tool used to probe for syrup) were used as experimental stimuli. The subjects demonstrated the ability to recognize that exchanges could occur when an experimenter was present with a desirable food. Results indicate that subjects exhibited significant variation in their willingness to barter based upon the types of foods that were both in their possession and presented by the experimenter. Subjects more readily traded chow biscuits for fruit, and more readily traded apples for grapes than grapes for apples. During the exchange of tools and food, the subjects preferred the following in descending order when the probing apparatus was baited with sweet syrup: grapes, metal bolts, and chow biscuits. However when the apparatus was not baited, the values changed to the following in descending order: grapes, chow, and metal bolts. These results indicate that tufted capuchins recognize opportunities to exchange and engage in a simple barter system whereby low-valued foods are readily traded for more highly valued food. Furthermore, these capuchins demonstrate that their value for a tool changes depending upon its utility. |
| Address |
Division of Research and Development, LABS of Virginia, Inc., 95 Castle Hall Road, P.O. Box 557, Yemassee, SC 29945, USA. Gwprimate@netscape.net |
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English |
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| ISSN |
1435-9448 |
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| Notes |
PMID:12884078 |
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no |
| Call Number |
Equine Behaviour @ team @ |
Serial |
2562 |
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| Author |
Davies, R.B.; Clark, G.G. |
| Title |
Trypanosomes from elk and horse flies in New Mexico |
Type |
Journal Article |
| Year |
1974 |
Publication |
Journal of Wildlife Diseases |
Abbreviated Journal |
J Wildl Dis |
| Volume |
10 |
Issue |
1 |
Pages |
63-65 |
| Keywords |
Animals; *Artiodactyla; Blood/microbiology; *Diptera; Ecology; *Insect Vectors; New Mexico; Trypanosoma/*isolation & purification; Trypanosomiasis/microbiology/*veterinary |
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English |
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| ISSN |
0090-3558 |
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| Notes |
PMID:4810218 |
Approved |
no |
| Call Number |
Equine Behaviour @ team @ |
Serial |
2709 |
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| Author |
Cleveland, A.; Rocca, A.M.; Wendt, E.L.; Westergaard, G.C. |
| Title |
Transport of tools to food sites in tufted capuchin monkeys (Cebus apella) |
Type |
Journal Article |
| Year |
2004 |
Publication |
Animal Cognition |
Abbreviated Journal |
Anim. Cogn. |
| Volume |
7 |
Issue |
3 |
Pages |
193-198 |
| Keywords |
Animals; *Association Learning; Cebus/*psychology; *Concept Formation; *Feeding Behavior; Female; Male; *Problem Solving |
| Abstract |
Tool use and transport represent cognitively important aspects of early hominid evolution, and nonhuman primates are often used as models to examine the cognitive, ecological, morphological and social correlates of these behaviors in order to gain insights into the behavior of our early human ancestors. In 2001, Jalles-Filho et al. found that free-ranging capuchin monkeys failed to transport tools (stones) to food sites (nuts), but transported the foods to the tool sites. This result cast doubt on the usefulness of Cebus to model early human tool-using behavior. In this study, we examined the performance of six captive tufted capuchin monkeys (Cebus apella) in a tool transport task. Subjects were provided with the opportunity to transport two different tools to fixed food reward sites when the food reward was visible from the tool site and when the food reward was not visible from the tool site. We found that the subjects quickly and readily transported probing tools to an apparatus baited with syrup, but rarely transported stones to a nut-cracking apparatus. We suggest that the performance of the capuchins here reflects an efficient foraging strategy, in terms of energy return, among wild Cebus monkeys. |
| Address |
Alpha Genesis, 95 Castle Hall Road, P.O. Box 557, Yemassee, SC 29945, USA |
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English |
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1435-9448 |
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| Notes |
PMID:15022055 |
Approved |
no |
| Call Number |
Equine Behaviour @ team @ |
Serial |
2539 |
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| Author |
Judge, N.G. |
| Title |
Transport of horses |
Type |
Journal Article |
| Year |
1969 |
Publication |
Australian Veterinary Journal |
Abbreviated Journal |
Aust Vet J |
| Volume |
45 |
Issue |
10 |
Pages |
465-469 |
| Keywords |
Aircraft; Animals; Australia; Automobiles; Behavior, Animal; Equipment and Supplies/veterinary; *Horses; Methods; *Movement; Ships; Veterinary Medicine |
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English |
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Edition |
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| ISSN |
0005-0423 |
ISBN |
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| Notes |
PMID:5408645 |
Approved |
no |
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refbase @ user @ |
Serial |
1968 |
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| Author |
Lazareva, O.F.; Smirnova, A.A.; Bagozkaja, M.S.; Zorina, Z.A.; Rayevsky, V.V.; Wasserman, E.A. |
| Title |
Transitive responding in hooded crows requires linearly ordered stimuli |
Type |
Journal Article |
| Year |
2004 |
Publication |
Journal of the experimental analysis of behavior |
Abbreviated Journal |
J Exp Anal Behav |
| Volume |
82 |
Issue |
1 |
Pages |
1-19 |
| Keywords |
Animals; *Association; Cognition/physiology; Crows; Discrimination (Psychology); *Discrimination Learning; Feedback; Reinforcement (Psychology); Visual Perception/physiology |
| Abstract |
Eight crows were taught to discriminate overlapping pairs of visual stimuli (A+ B-, B+ C-, C+ D-, and D+ E-). For 4 birds, the stimuli were colored cards with a circle of the same color on the reverse side whose diameter decreased from A to E (ordered feedback group). These circles were made available for comparison to potentially help the crows order the stimuli along a physical dimension. For the other 4 birds, the circles corresponding to the colored cards had the same diameter (constant feedback group). In later testing, a novel choice pair (BD) was presented. Reinforcement history involving stimuli B and D was controlled so that the reinforcement/nonreinforcement ratios for the latter would be greater than for the former. If, during the BD test, the crows chose between stimuli according to these reinforcement/nonreinforcement ratios, then they should prefer D; if they chose according to the diameter of the feedback stimuli, then they should prefer B. In the ordered feedback group, the crows strongly preferred B over D; in the constant feedback group, the crows' choice did not differ significantly from chance. These results, plus simulations using associative models, suggest that the orderability of the postchoice feedback stimuli is important for crows' transitive responding. |
| Address |
Institute of Higher Nervous Activity, Moscow State University. olga-lazareva@uiowa.edu |
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English |
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Edition |
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0022-5002 |
ISBN |
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| Notes |
PMID:15484868 |
Approved |
no |
| Call Number |
refbase @ user @ |
Serial |
612 |
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| Author |
Lonon, A.M.; Zentall, T.R. |
| Title |
Transfer of value from S+ to S- in simultaneous discriminations in humans |
Type |
Journal Article |
| Year |
1999 |
Publication |
The American journal of psychology |
Abbreviated Journal |
Am J Psychol |
| Volume |
112 |
Issue |
1 |
Pages |
21-39 |
| Keywords |
Adolescent; Adult; Animals; Color Perception; Columbidae; Conditioning, Classical; *Discrimination Learning; Female; Humans; Male; Middle Aged; *Motivation; Orientation; Pattern Recognition, Visual; Psychomotor Performance; Reaction Time; *Transfer (Psychology) |
| Abstract |
When animals learn a simultaneous discrimination, some of the value of the positive stimulus (S+) appears to transfer to the negative stimulus (S-). The present experiments demonstrate that such value transfer can also be found in humans. In Experiment 1 humans were trained on 2 simple simultaneous discriminations, the first between a highly positive stimulus, A (1,000 points); and a negative stimulus, B (0 points); and the second between a less positive stimulus, C (100 points); and a negative stimulus, D (0 points). On test trials, most participants preferred B over D. In Experiments 2 and 3 the value of the 2 original discriminations was equated in training (A[100]B[0] and C[100]D[0]). In Experiment 2 the values of the positive stimuli were then altered (A[1,000]C[0]); again, most participants preferred B over D. In Experiment 3, however, when the values of B and D were altered (B[1,000]D[0]), participants were indifferent to A and C. Thus, the mechanism that underlies value transfer in humans appears to be related to Pavlovian second-order conditioning. Similar mechanisms may be involved in assimilation processes in social contexts. |
| Address |
University of Kentucky, USA |
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English |
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Edition |
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0002-9556 |
ISBN |
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| Notes |
PMID:10696277 |
Approved |
no |
| Call Number |
refbase @ user @ |
Serial |
249 |
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| Author |
Zentall, T.R.; Sherburne, L.M. |
| Title |
Transfer of value from S+ to S- in a simultaneous discrimination |
Type |
Journal Article |
| Year |
1994 |
Publication |
Journal of experimental psychology. Animal behavior processes |
Abbreviated Journal |
J Exp Psychol Anim Behav Process |
| Volume |
20 |
Issue |
2 |
Pages |
176-183 |
| Keywords |
Animals; *Appetitive Behavior; Attention; Color Perception; Columbidae; *Discrimination Learning; Female; Male; Motivation; Orientation; Pattern Recognition, Visual; *Problem Solving; *Reinforcement Schedule; *Transfer (Psychology) |
| Abstract |
Value transfer theory has been proposed to account for transitive inference effects (L. V. Fersen, C. D. L. Wynne, J. D. Delius, & J. E. R. Staddon, 1991), in which following training on 4 simultaneous discriminations (A+B-, B+C-, C+D-, D+E-) pigeons show a preference for B over D. According to this theory, some of the value of reinforcement acquired by each S+ transfers to the S-. In the transitive inference experiment, C (associated with both reward and nonreward) can transfer less value to D than A (associated only with reward) can transfer to B. Support for value transfer theory was demonstrated in 2 experiments in which an S- presented in the context of a stimulus to which responses were always reinforced (S+) was preferred over an S- presented in the context of a stimulus to which responses were sometimes reinforced (S +/-). |
| Address |
Department of Psychology, University of Kentucky, Lexington 40506 |
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English |
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0097-7403 |
ISBN |
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| Notes |
PMID:8189186 |
Approved |
no |
| Call Number |
refbase @ user @ |
Serial |
258 |
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| Author |
Urcuioli, P.J.; DeMarse, T.B.; Zentall, T.R. |
| Title |
Transfer across delayed discriminations: II. Differences in the substitutability of initial versus test stimuli |
Type |
Journal Article |
| Year |
1998 |
Publication |
Journal of experimental psychology. Animal behavior processes |
Abbreviated Journal |
J Exp Psychol Anim Behav Process |
| Volume |
24 |
Issue |
1 |
Pages |
47-59 |
| Keywords |
Animals; Behavior, Animal; Columbidae/physiology; Discrimination Learning/*physiology; Pattern Recognition, Visual/*physiology; Reinforcement (Psychology); Retention (Psychology)/physiology |
| Abstract |
In 2 experiments, pigeons were trained on, and then transferred to, delayed simple discriminations in which the initial stimuli signalled reinforcement versus extinction following a retention interval. Experiment 1 showed that discriminative responding on the retention test transferred to novel test stimuli that had appeared in another delayed simple discrimination but not to stimuli having the same reinforcement history off-baseline. By contrast, Experiment 2 showed that performances transferred to novel initial stimuli whether they had been trained on-baseline or off-baseline. These results suggest that the test stimuli in delayed simple discriminations acquire control over responding only in the memory task itself. On the other hand, control by the initial stimuli, if coded as outcome expectancies, does not require such task-specific training. |
| Address |
Department of Psychological Sciences, Purdue University, West Lafayette, Indiana 47907-1364, USA. uche@psych.purdue.edu |
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English |
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0097-7403 |
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| Notes |
PMID:9438965 |
Approved |
no |
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refbase @ user @ |
Serial |
253 |
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| Author |
Urcuioli, P.J.; Zentall, T.R. |
| Title |
Transfer across delayed discriminations: evidence regarding the nature of prospective working memory |
Type |
Journal Article |
| Year |
1992 |
Publication |
Journal of experimental psychology. Animal behavior processes |
Abbreviated Journal |
J Exp Psychol Anim Behav Process |
| Volume |
18 |
Issue |
2 |
Pages |
154-173 |
| Keywords |
Animals; *Appetitive Behavior; Attention; *Color Perception; Columbidae; *Discrimination Learning; *Mental Recall; *Pattern Recognition, Visual; Problem Solving; Retention (Psychology); *Transfer (Psychology) |
| Abstract |
Pigeons were trained successively either on 2 delayed simple discriminations or on a delayed simple discrimination followed by delayed matching-to-sample. During subsequent transfer tests, the initial stimuli from the 1st task were substituted for those in the 2nd. Performances transferred immediately if both sets of initial stimuli had been associated with the presence versus absence of food on their respective retention tests, and the direction of transfer (positive or negative) depended on whether the substitution involved stimuli with identical or different outcome associates. No transfer was found, however, when the initial stimuli were associated with different patterns of responding but food occurred at the end of every trial. These results are consistent with outcome expectancy mediation but are incompatible with response intention and retrospective coding accounts. |
| Address |
Department of Psychological Sciences, Purdue University, West Lafayette, Indiana 47907-1364 |
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English |
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0097-7403 |
ISBN |
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Conference |
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| Notes |
PMID:1583445 |
Approved |
no |
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refbase @ user @ |
Serial |
260 |
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