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Author |
Andersen, N.H.; Norgaard, A.; Jensen, T.J.; Ulstrup, J. |
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Title |
Sequential unfolding of the two-domain protein Pseudomonas stutzeri cytochrome c4 |
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Journal Article |
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Year |
2002 |
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Journal of Inorganic Biochemistry |
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88 |
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3-4 |
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316-327 |
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P. stutzeri cytochrome c4; Sequential unfolding; Di-haem protein; Unfolding |
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Abstract |
P. stutzeri cytochrome c4 is a di-haem protein, composed of two globular domains each with His-Met coordinated haem, and a hydrogen bond network between the domains. The domain foldings are highly symmetric but with specific differences including structural differences of ligand coordination, and different spin states of the oxidised haem groups. We have studied unfolding of oxidised P. stutzeri cyt c4 induced thermally and by chemical denaturants. Horse heart cyt c was a reference molecule. Isothermal unfolding induced by guanidinium chloride and acid was followed by Soret, α/β, and 701-nm band absorption, and by far-UV circular dichroism spectroscopy. Multifarious patterns emerge, but the two domains clearly unfold sequentially. One phase, assigned to unfolding of the N-terminal domain, proceeds at guanidinium concentrations up to [approximate]1.0 M. This is followed by two overlapping phases at higher concentrations. The intermediate state maintains Fe-Met coordination, assigned to the C-terminal domain. Interdomain interaction is reflected in decreasing values of the cooperativity parameters. Differential scanning calorimetry shows a single peak, but two peaks appear when guanidinium chloride up to 0.4 M is present. This reflects different chemical action in chemical and thermal unfolding. Acid-induced unfolding kinetics was addressed by pH jumps using diode array stopped-flow techniques. Three kinetic phases in the 701 nm Fe-Met marker band, and four phases in the Soret and α/β bands, spanning 4-1000 ms could be distinguished on pH jumps from 7.5 to the range 2.5-3.5. In this range of time and pH cyt c appears to unfold in no more than two phases. Spectral properties of the kinetic intermediates could be identified. Sequential domain unfolding, formation of high-spin states, and an intermediate state with Fe-Met coordination to a single haem group are features of the unfolding kinetics. |
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3973 |
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Kaiser, D.H.; Zentall, T.R.; Neiman, E. |
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Title |
Timing in pigeons: effects of the similarity between intertrial interval and gap in a timing signal |
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Journal Article |
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Year |
2002 |
Publication |
Journal of experimental psychology. Animal behavior processes |
Abbreviated Journal |
J Exp Psychol Anim Behav Process |
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28 |
Issue |
4 |
Pages |
416-422 |
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Animals; *Attention; Columbidae; *Conditioning, Operant; Discrimination Learning; Mental Recall; Probability Learning; *Reinforcement (Psychology); *Reinforcement Schedule; Retention (Psychology); Time Factors; *Time Perception/physiology |
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Previous research suggests that when a fixed interval is interrupted (known as the gap procedure), pigeons tend to reset memory and start timing from 0 after the gap. However, because the ambient conditions of the gap typically have been the same as during the intertrial interval (ITI), ambiguity may have resulted. In the present experiment, the authors found that when ambient conditions during the gap were similar to the ITI, pigeons tended to reset memory, but when ambient conditions during the gap were different from the ITI, pigeons tended to stop timing, retain the duration of the stimulus in memory, and add to that time when the stimulus reappeared. Thus, when the gap was unambiguous, pigeons timed accurately. |
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Department of Psychology, East Carolina University, Greenville, North Carolina 27858, USA. kaiserd@mail.ecu.edu |
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0097-7403 |
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PMID:12395499 |
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refbase @ user @ |
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238 |
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Clement, T.S.; Zentall, T.R. |
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Second-order contrast based on the expectation of effort and reinforcement |
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Journal Article |
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Year |
2002 |
Publication |
Journal of experimental psychology. Animal behavior processes |
Abbreviated Journal |
J Exp Psychol Anim Behav Process |
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28 |
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1 |
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64-74 |
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Animals; Columbidae; Discrimination Learning; Random Allocation; *Reinforcement (Psychology) |
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Pigeons prefer signals for reinforcement that require greater effort (or time) to obtain over those that require less effort to obtain (T. S. Clement, J. Feltus, D. H. Kaiser, & T. R. Zentall, 2000). Preference was attributed to contrast (or to the relatively greater improvement in conditions) produced by the appearance of the signal when it was preceded by greater effort. In Experiment 1, the authors of the present study demonstrated that the expectation of greater effort was sufficient to produce such a preference (a second-order contrast effect). In Experiments 2 and 3, low versus high probability of reinforcement was substituted for high versus low effort, respectively, with similar results. In Experiment 3, the authors found that the stimulus preference could be attributed to positive contrast (when the discriminative stimuli represented an improvement in the probability of reinforcement) and perhaps also negative contrast (when the discriminative stimuli represented reduction in the probability of reinforcement). |
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Department of Psychology, University of Kentucky, Lexington, Kentucky 40506-0044, USA |
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0097-7403 |
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PMID:11868235 |
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refbase @ user @ |
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241 |
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Author |
Zentall, T.R.; Clement, T.S. |
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Title |
Memory mechanisms in pigeons: evidence of base-rate neglect |
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Journal Article |
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Year |
2002 |
Publication |
Journal of experimental psychology. Animal behavior processes |
Abbreviated Journal |
J Exp Psychol Anim Behav Process |
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28 |
Issue |
1 |
Pages |
111-115 |
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Animals; Columbidae; Discrimination Learning; Memory/*physiology; Random Allocation; Reaction Time; Reinforcement (Psychology); Retention (Psychology) |
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In delayed matching to sample, once acquired, pigeons presumably choose comparisons according to their memory for (the strength of) the sample. When memory for the sample is sufficiently weak, comparison choice should depend on the history of reinforcement associated with each of the comparison stimuli. In the present research, pigeons acquired two matching tasks in which Sample S1 was associated with one comparison from each task, C1 and C3, whereas Sample S2 was associated with Comparison C2, and Sample S3 was associated with Comparison C4. As the retention interval increased, the pigeons showed a bias to choose the comparison (C1 or C3) associated with the more frequently occurring sample (S1). Thus, pigeons were sensitive also to the (irrelevant) likelihood that each of the samples was presented. The results suggest that pigeons may allow their reference memory for the overall sample frequency to influence comparison choice, independent of the comparison stimuli present. |
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Department of Psychology, University of Kentucky, Lexington, Kentucky 40506-0044, USA. zentall@pop.uky.edu |
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0097-7403 |
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PMID:11868229 |
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no |
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refbase @ user @ |
Serial |
242 |
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Author |
Shettleworth, S.J.; Westwood, R.P. |
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Title |
Divided attention, memory, and spatial discrimination in food-storing and nonstoring birds, black-capped chickadees (Poecile atricapilla) and dark-eyed juncos (Junco hyemalis) |
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Journal Article |
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Year |
2002 |
Publication |
Journal of experimental psychology. Animal behavior processes |
Abbreviated Journal |
J Exp Psychol Anim Behav Process |
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28 |
Issue |
3 |
Pages |
227-241 |
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Animals; Attention/*physiology; Behavior, Animal/physiology; Birds; *Discrimination (Psychology); *Food Habits; Memory/*physiology; Space Perception/*physiology; Spatial Behavior/*physiology |
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Food-storing birds, black-capped chickadees (Poecile atricapilla), and nonstoring birds, dark-eyed juncos (Junco hyemalis), matched color or location on a touch screen. Both species showed a divided attention effect for color but not for location (Experiment 1). Chickadees performed better on location than on color with retention intervals up to 40 s, but juncos did not (Experiment 2). Increasing sample-distractor distance improved performance similarly in both species. Multidimensional scaling revealed that both use a Euclidean metric of spatial similarity (Experiment 3). When choosing between the location and color of a remembered item, food storers choose location more than do nonstorers. These results explain this effect by differences in memory for location relative to color, not division of attention or spatial discrimination ability. |
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Department of Psychology, University of Toronto, 100 Saint George Street, Toronto, Ontario M5S 3G3, Canada. shettle@psych.utoronto.ca |
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0097-7403 |
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PMID:12136700 |
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refbase @ user @ |
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370 |
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Author |
Manns, J.R.; Clark, R.E.; Squire, L.R. |
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Title |
Standard delay eyeblink classical conditioning is independent of awareness |
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Journal Article |
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Year |
2002 |
Publication |
Journal of Experimental Psychology. Animal Behavior Processes |
Abbreviated Journal |
J Exp Psychol Anim Behav Process |
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28 |
Issue |
1 |
Pages |
32-37 |
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Aged; *Awareness; *Blinking; *Conditioning, Classical; Humans |
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P. F. Lovibond and D. R. Shanks (2002) suggested that all forms of classical conditioning depend on awareness of the stimulus contingencies. This article considers the available data for eyeblink classical conditioning, including data from 2 studies (R. E. Clark, J. R. Manns, & L. R. Squire, 2001; J. R. Manns, R. E. Clark, & L. R. Squire, 2001) that were completed too recently to have been considered in their review. In addition, in response to questions raised by P. F. Lovibond and D. R. Shanks, 2 new analyses of data are presented from studies published previously. The available data from humans and experimental animals provide strong evidence that delay eyeblink classical conditioning (but not trace eyeblink classical conditioning) can be acquired and retained independently of the forebrain and independently of awareness. This conclusion applies to standard conditioning paradigms; for example, to single-cue delay conditioning when a tone is used as the conditioned stimulus (CS) and to differential delay conditioning when the positive and negative conditioned stimuli (CS+ and CS-) are a tone and white noise. |
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Department of Psychology, University of California, San Diego, USA |
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0097-7403 |
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PMID:11868232 |
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Equine Behaviour @ team @ |
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2769 |
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Dyson, S. |
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Title |
Lameness and poor performance in the sport horse: Dressage, show jumping and horse trials |
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Journal Article |
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2002 |
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Journal of Equine Veterinary Science |
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22 |
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4 |
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145-150 |
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3957 |
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Bello, T.R. |
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Practical treatment of body and open leg wounds of horses with bovine collagen, biosynthetic wound dressing and cyanoacrylate |
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2002 |
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Journal of Equine Veterinary Science |
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22 |
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4 |
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157-164 |
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Horses with severe and deep lacerations are represented by ten cases in which treatment emphasized the use of bovine collagen preparations to promote controlled second-degree repair. Traumatized areas were tarsal, metatarsal, neck, forearm, metacarpal and pastern. Wound size changes were recorded. Depending on the wound type, the site was treated with antibiotic-steroid ointment, organic acid cream, sterile collagen particles, suspension or dressings protected by hydrogel dressing, non-adherent pads, occlusive skin dressings, roll gauze and elastic tape. In three cases, a fiberglas cast was applied over a hind leg wound and lacerated tendon for stability. When controlled granulation of the deeper wounds reached skin level, the area often was stabilized by only cyanoacrylate spray. As these cases presented a wide range of trauma each with a unique history, healing rates were based on initial measurements. An overall progression of wound reduction occurred at a predictable rate. The exogenous collagen formulations were used to stimulate controlled granulation, ie. to “jump start” the healing process. Collagen particles, suspension or dressings were packed into depressions, placed under suture lines, secured over abraded tissue, and placed under protective bandage or cast. To further evaluate the use of cyanoacrylate tissue spray in wound treatments, an additional ten cases are presented. The variety of wounds were produced experimentally in Center-owned ponies or provided as clinical cases. Wound size changes and healing progress were recorded. Wounds occurred on the neck, abdomen, metacarpal, metatarsal, fetlock and pastern areas. Depending on wound type, the site was treated with cyanoacrylate only; or treated as above until controlled granulation attained skin level. In one case punch grafts of skin were transferred from one foreleg to the opposite with the horse standing. Cyanoacrylate spray provided a water proof barrier protecting the wound from dirt, debris and insects as well as stabilizing full-thickness skin lacerations by bridging normal to traumatized skin allowing uninterrupted granulation and epithelialization. The use of a neck cradle prevented wound disturbance and stall confinement aided stabilization. |
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3972 |
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Pirasteh, A. |
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Title |
Dr. Strasser's methods not to just save money |
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2002 |
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Journal of Equine Veterinary Science |
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22 |
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3 |
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102-103 |
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Equine Behaviour @ team @ |
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4663 |
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Author |
Weaver, A.; de Waal, F.B.M. |
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An index of relationship quality based on attachment theory |
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2002 |
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Journal of comparative psychology (Washington, D.C. : 1983) |
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J Comp Psychol |
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116 |
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1 |
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93-106 |
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Analysis of Variance; Animals; *Behavior, Animal; Female; Male; *Maternal Behavior; *Object Attachment; Pan troglodytes/*psychology; Pilot Projects |
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Two measures are reported of the nature or quality of a mother-offspring (MO) relationship during development using brown capuchin monkeys (Cebus apella) as models. One is a qualitative classification of MO relationships as secure, resistant, or avoidant attachments. The other is an empirical ratio of relative affiliation to agonism called the MO relationship quality, or MORQ, Index. The two methods tapped similar relationship features so relationships high or low of a median split of MORQ values were heuristically labeled secure (n = 22) or insecure (n = 16), respectively. A comparison revealed extensive behavioral differences between secure and insecure MO relationships and suggested MORQ provided an objective, continuous measure of attachment security. |
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Yerkes Regional Primate Research Center, Emory University, USA. achweaver@att.net |
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0735-7036 |
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PMID:11930937 |
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refbase @ user @ |
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183 |
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