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Author |
Vallortigara, G.; Rogers, L.J. |
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Title |
Survival with an asymmetrical brain: advantages and disadvantages of cerebral lateralization |
Type |
Journal Article |
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Year |
2005 |
Publication |
The Behavioral and Brain Sciences |
Abbreviated Journal |
Behav Brain Sci |
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Volume |
28 |
Issue |
4 |
Pages |
575-89; discussion 589-633 |
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Keywords |
Animals; Attention/*physiology; Behavior/*physiology; Behavior, Animal/*physiology; Dominance, Cerebral/*physiology; *Evolution; Humans; Models, Biological; Visual Perception/physiology |
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Abstract |
Recent evidence in natural and semi-natural settings has revealed a variety of left-right perceptual asymmetries among vertebrates. These include preferential use of the left or right visual hemifield during activities such as searching for food, agonistic responses, or escape from predators in animals as different as fish, amphibians, reptiles, birds, and mammals. There are obvious disadvantages in showing such directional asymmetries because relevant stimuli may be located to the animal's left or right at random; there is no a priori association between the meaning of a stimulus (e.g., its being a predator or a food item) and its being located to the animal's left or right. Moreover, other organisms (e.g., predators) could exploit the predictability of behavior that arises from population-level lateral biases. It might be argued that lateralization of function enhances cognitive capacity and efficiency of the brain, thus counteracting the ecological disadvantages of lateral biases in behavior. However, such an increase in brain efficiency could be obtained by each individual being lateralized without any need to align the direction of the asymmetry in the majority of the individuals of the population. Here we argue that the alignment of the direction of behavioral asymmetries at the population level arises as an “evolutionarily stable strategy” under “social” pressures occurring when individually asymmetrical organisms must coordinate their behavior with the behavior of other asymmetrical organisms of the same or different species. |
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Department of Psychology and B.R.A.I.N. Centre for Neuroscience, University of Trieste, 34123 Trieste, Italy. vallorti@univ.trieste.it |
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0140-525X |
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PMID:16209828 |
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Equine Behaviour @ team @ |
Serial |
4622 |
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Author |
Wilson, A.M.; McGuigan, M.P.; Su, A.; van Den Bogert, A.J. |
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Title |
Horses damp the spring in their step |
Type |
Journal Article |
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Year |
2001 |
Publication |
Nature |
Abbreviated Journal |
Nature |
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Volume |
414 |
Issue |
6866 |
Pages |
895-899 |
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Keywords |
Animals; Biomechanics; Elasticity; Forelimb; Gait; Horses/anatomy & histology/*physiology; Leg Bones/*physiology; Locomotion; Models, Biological; Muscle Fibers/physiology; Muscle, Skeletal/anatomy & histology/*physiology; Tendons/anatomy & histology/*physiology; Vibration |
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Abstract |
The muscular work of galloping in horses is halved by storing and returning elastic strain energy in spring-like muscle-tendon units.These make the legs act like a child's pogo stick that is tuned to stretch and recoil at 2.5 strides per second. This mechanism is optimized by unique musculoskeletal adaptations: the digital flexor muscles have extremely short fibres and significant passive properties, whereas the tendons are very long and span several joints. Length change occurs by a stretching of the spring-like digital flexor tendons rather than through energetically expensive length changes in the muscle. Despite being apparently redundant for such a mechanism, the muscle fibres in the digital flexors are well developed. Here we show that the mechanical arrangement of the elastic leg permits it to vibrate at a higher frequency of 30-40 Hz that could cause fatigue damage to tendon and bone. Furthermore, we show that the digital flexor muscles have minimal ability to contribute to or regulate significantly the 2.5-Hz cycle of movement, but are ideally arranged to damp these high-frequency oscillations in the limb. |
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Department of Veterinary Basic Sciences, The Royal Veterinary College, Hatfield, Herts AL9 7TA, UK. awilson@rvc.ac.uk |
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0028-0836 |
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PMID:11780059 |
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Equine Behaviour @ team @ |
Serial |
2300 |
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Author |
Harcourt, J.L.; Ang, T.Z.; Sweetman, G.; Johnstone, R.A.; Manica, A. |
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Title |
Social feedback and the emergence of leaders and followers |
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Journal Article |
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Year |
2009 |
Publication |
Current Biology : CB |
Abbreviated Journal |
Curr Biol |
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Volume |
19 |
Issue |
3 |
Pages |
248-252 |
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Keywords |
Analysis of Variance; Animals; Appetitive Behavior/physiology; *Feedback; Great Britain; *Leadership; Markov Chains; Models, Biological; Monte Carlo Method; Smegmamorpha/*physiology; *Social Behavior; Video Recording |
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Abstract |
In many animal groups, certain individuals consistently appear at the forefront of coordinated movements [1-4]. How such leaders emerge is poorly understood [5, 6]. Here, we show that in pairs of sticklebacks, Gasterosteus aculeatus, leadership arises from individual differences in the way that fish respond to their partner's movements. Having first established that individuals differed in their propensity to leave cover in order to look for food, we randomly paired fish of varying boldness, and we used a Markov Chain model to infer the individual rules underlying their joint behavior. Both fish in a pair responded to each other's movements-each was more likely to leave cover if the other was already out and to return if the other had already returned. However, we found that bolder individuals displayed greater initiative and were less responsive to their partners, whereas shyer individuals displayed less initiative but followed their partners more faithfully; they also, as followers, elicited greater leadership tendencies in their bold partners. We conclude that leadership in this case is reinforced by positive social feedback. |
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Address |
Department of Zoology, University of Cambridge, Cambridge, UK |
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English |
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0960-9822 |
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Notes |
PMID:19185497 |
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no |
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Call Number |
Equine Behaviour @ team @ |
Serial |
5123 |
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Author |
Brilot, B.O.; Johnstone, R.A. |
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Title |
The limits to cost-free signalling of need between relatives |
Type |
Journal Article |
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Year |
2003 |
Publication |
Proceedings. Biological sciences / The Royal Society |
Abbreviated Journal |
Proc Biol Sci |
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Volume |
270 |
Issue |
1519 |
Pages |
1055-1060 |
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Keywords |
*Animal Communication; Animals; Birds/physiology; Models, Biological; *Social Behavior |
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Abstract |
Theoretical models have demonstrated the possibility of stable cost-free signalling of need between relatives. The stability of these cost-free equilibria depends on the indirect fitness cost of cheating and deceiving a donor into giving away resources. We show that this stability is highly sensitive to the distribution of need among signallers and receivers. In particular, cost-free signalling is likely to prove stable only if there is very large variation in need (such that the least-needy individuals stand to gain much less than the most-needy individuals from additional resources). We discuss whether these conditions are likely to be found in altricial avian breeding systems--the most intensively studied instance of signalling of need between relatives. We suggest that cost-free signalling is more likely to prove stable and will provide parents with more information during the earlier phases of chick growth, when parents can more easily meet the demands of a brood (and chicks are more likely to reach satiation). Later, informative yet cost-free signalling is unlikely to persist. |
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Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK. bob21@cam.ac.uk |
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English |
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0962-8452 |
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Notes |
PMID:12803895 |
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no |
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Call Number |
refbase @ user @ |
Serial |
558 |
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Author |
Rands, S.A.; Cowlishaw, G.; Pettifor, R.A.; Rowcliffe, J.M.; Johnstone, R.A. |
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Title |
Spontaneous emergence of leaders and followers in foraging pairs |
Type |
Journal Article |
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Year |
2003 |
Publication |
Nature |
Abbreviated Journal |
Nature |
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Volume |
423 |
Issue |
6938 |
Pages |
432-434 |
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Keywords |
Animals; *Energy Metabolism; Food; *Food Chain; *Models, Biological; Motor Activity; *Social Behavior; Time Factors |
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Abstract |
Animals that forage socially often stand to gain from coordination of their behaviour. Yet it is not known how group members reach a consensus on the timing of foraging bouts. Here we demonstrate a simple process by which this may occur. We develop a state-dependent, dynamic game model of foraging by a pair of animals, in which each individual chooses between resting or foraging during a series of consecutive periods, so as to maximize its own individual chances of survival. We find that, if there is an advantage to foraging together, the equilibrium behaviour of both individuals becomes highly synchronized. As a result of this synchronization, differences in the energetic reserves of the two players spontaneously develop, leading them to adopt different behavioural roles. The individual with lower reserves emerges as the 'pace-maker' who determines when the pair should forage, providing a straightforward resolution to the problem of group coordination. Moreover, the strategy that gives rise to this behaviour can be implemented by a simple 'rule of thumb' that requires no detailed knowledge of the state of other individuals. |
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Address |
Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK. s.rands@zoo.cam.ac.uk |
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English |
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0028-0836 |
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Notes |
PMID:12761547 |
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no |
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Call Number |
Equine Behaviour @ team @ |
Serial |
5138 |
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Author |
Rands, S.A.; Cowlishaw, G.; Pettifor, R.A.; Rowcliffe, J.M.; Johnstone, R.A. |
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Title |
The emergence of leaders and followers in foraging pairs when the qualities of individuals differ |
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Journal Article |
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Year |
2008 |
Publication |
BMC Evolutionary Biology |
Abbreviated Journal |
BMC Evol Biol |
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Volume |
8 |
Issue |
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Pages |
51 |
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Keywords |
Animals; *Feeding Behavior; *Food Chain; *Models, Biological; *Social Dominance |
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Abstract |
BACKGROUND: Foraging in groups offers animals a number of advantages, such as increasing their likelihood of finding food or detecting and avoiding predators. In order for a group to remain together, there has to be some degree of coordination of behaviour and movement between its members (which may in some cases be initiated by a decision-making leader, and in other cases may emerge as an underlying property of the group). For example, behavioural synchronisation is a phenomenon where animals within a group initiate and then continue to conduct identical behaviours, and has been characterised for a wide range of species. We examine how a pair of animals should behave using a state-dependent approach, and ask what conditions are likely to lead to behavioural synchronisation occurring, and whether one of the individuals is more likely to act as a leader. RESULTS: The model we describe considers how the energetic gain, metabolic requirements and predation risks faced by the individuals affect measures of their energetic state and behaviour (such as the degree of behavioural synchronisation seen within the pair, and the value to an individual of knowing the energetic state of its colleague). We explore how predictable changes in these measures are in response to changes in physiological requirements and predation risk. We also consider how these measures should change when the members of the pair are not identical in their metabolic requirements or their susceptibility to predation. We find that many of the changes seen in these measures are complex, especially when asymmetries exist between the members of the pair. CONCLUSION: Analyses are presented that demonstrate that, although these general patterns are robust, care needs to be taken when considering the effects of individual differences, as the relationship between individual differences and the resulting qualitative changes in behaviour may be complex. We discuss how these results are related to experimental observations, and how the model and its predictions could be extended. |
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Address |
Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK. sean.rands@bristol.ac.uk |
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English |
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1471-2148 |
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PMID:18282297 |
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no |
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Equine Behaviour @ team @ |
Serial |
5126 |
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Author |
Kiltie, R.A.; Fan, J.; Laine, A.F. |
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Title |
A wavelet-based metric for visual texture discrimination with applications in evolutionary ecology |
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Journal Article |
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Year |
1995 |
Publication |
Mathematical Biosciences |
Abbreviated Journal |
Math Biosci |
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Volume |
126 |
Issue |
1 |
Pages |
21-39 |
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Keywords |
Animals; Carnivora; *Ecology; Equidae; *Evolution; Humans; Mathematics; Models, Biological; Moths; *Pattern Recognition, Visual; Pigmentation |
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Abstract |
Much work on natural and sexual selection is concerned with the conspicuousness of visual patterns (textures) on animal and plant surfaces. Previous attempts by evolutionary biologists to quantify apparency of such textures have involved subjective estimates of conspicuousness or statistical analyses based on transect samples. We present a method based on wavelet analysis that avoids subjectivity and that uses more of the information in image textures than transects do. Like the human visual system for texture discrimination, and probably like that of other vertebrates, this method is based on localized analysis of orientation and frequency components of the patterns composing visual textures. As examples of the metric's utility, we present analyses of crypsis for tigers, zebras, and peppered moth morphs. |
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Department of Zoology, University of Florida, Gainesville |
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English |
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0025-5564 |
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PMID:7696817 |
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Equine Behaviour @ team @ |
Serial |
2660 |
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Author |
Biro, D.; Sumpter, D.J.T.; Meade, J.; Guilford, T. |
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Title |
From Compromise to Leadership in Pigeon Homing |
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Journal Article |
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Year |
2006 |
Publication |
Current Biology |
Abbreviated Journal |
Curr Biol |
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Volume |
16 |
Issue |
21 |
Pages |
2123-2128 |
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Keywords |
Animal Migration; Animals; Columbidae/*physiology; Decision Making; *Flight, Animal; *Homing Behavior; Models, Biological; Orientation; *Social Behavior; *Social Dominance |
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Abstract |
Summary A central problem faced by animals traveling in groups is how navigational decisions by group members are integrated, especially when members cannot assess which individuals are best informed or have conflicting information or interests , , , and . Pigeons are now known to recapitulate faithfully their individually distinct habitual routes home , and , and this provides a novel paradigm for investigating collective decisions during flight under varying levels of interindividual conflict. Using high-precision GPS tracking of pairs of pigeons, we found that if conflict between two birds' directional preferences was small, individuals averaged their routes, whereas if conflict rose over a critical threshold, either the pair split or one of the birds became the leader. Modeling such paired decision-making showed that both outcomes--compromise and leadership--could emerge from the same set of simple behavioral rules. Pairs also navigated more efficiently than did the individuals of which they were composed, even though leadership was not necessarily assumed by the more efficient bird. In the context of mass migration of birds and other animals, our results imply that simple self-organizing rules can produce behaviors that improve accuracy in decision-making and thus benefit individuals traveling in groups , and . |
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Department of Zoology, University of Oxford, Oxford OX1 3PS, United Kingdom. daro.biro@zoo.ox.ac.uk |
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Englisch |
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0960-9822 |
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Notes |
PMID:17084696 |
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no |
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Call Number |
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Serial |
2026 |
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Author |
Galloux, P.; Barrey, E. |
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Title |
Components of the total kinetic moment in jumping horses |
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Journal Article |
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Year |
1997 |
Publication |
Equine Veterinary Journal. Supplement |
Abbreviated Journal |
Equine Vet J Suppl |
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23 |
Pages |
41-44 |
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Keywords |
Algorithms; Animals; Exertion/*physiology; Female; Gravitation; Horses/*physiology; Kinetics; Locomotion/*physiology; Male; Models, Biological; Movement/*physiology; Video Recording |
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Abstract |
Thirty horses were filmed with a panning camera operating at 50 frames/s as they jumped over a 1.20 x 1.20 m fence. The markers of 9 joints on the horse and 7 joints on the rider were tracked in 2D with the TrackEye system. The centre of gravity and moment of inertia of each segment were calculated using a geometric algorithm and a cylindric model, respectively. The kinetic moment of each part of the horse was calculated after filtering, and resampling of data. This method showed the relative contribution of each body segment to the body overall rotation during the take-off, jump and landing phases. It was found that the trunk, hindlimbs and head-neck had the greatest influence. The coordination between the motion of the body segments allowed the horse to control its angular speed of rotation over the fence. This remained nearly constant during the airborne phase (120 +/- 5 degrees/s). During the airborne phase, the kinetic moment was constant because its value was equal to the moment of the external forces (722 +/- 125 kg x m2/s). |
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Address |
Ecole Nationale d'Equitation, Terrefort, Saumur, France |
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Notes |
PMID:9354287 |
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no |
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Call Number |
Equine Behaviour @ team @ |
Serial |
3797 |
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Author |
Rosa, P.A.J.; Azevedo, A.M.; Aires-Barros, M.R. |
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Title |
Application of central composite design to the optimisation of aqueous two-phase extraction of human antibodies |
Type |
Journal Article |
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Year |
2007 |
Publication |
Journal of Chromatography. A |
Abbreviated Journal |
J Chromatogr A |
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Volume |
1141 |
Issue |
1 |
Pages |
50-60 |
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Keywords |
Analysis of Variance; Animals; Antibodies/*chemistry/*isolation & purification; Buffers; Chemical Fractionation/*methods; Horses; Humans; Hydrophobicity; Isoelectric Point; Models, Biological; Molecular Weight; Myoglobin/chemistry/isolation & purification; Osmolar Concentration; Phase Transition; Polyethylene Glycols; Serum Albumin/chemistry/isolation & purification; Sodium Chloride |
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Abstract |
The partition of human antibodies in aqueous two-phase systems (ATPSs) of polyethylene glycol (PEG) and phosphate was systematically studied using first pure proteins systems and then an artificial mixture of proteins containing 1mg/ml human immunoglobulin G (IgG), 10mg/ml serum albumin and 2mg/ml myoglobin. Preliminary results obtained using pure proteins systems indicated that the PEG molecular weight and concentration, the pH value and the salts concentration had a pronounced effect on the partitioning behaviour of all proteins. For high ionic strengths and pH values higher than the isoelectric point (pI) of the contaminant proteins, IgG could be selectively recovered on the top phase. According to these results, a face centred composite design was performed in order to optimise the purification of IgG from the mixture of proteins. The optimal conditions for the isolation of IgG were observed for high concentrations of NaCl and low concentrations of both phase forming components. The best purification was achieved using an ATPS containing 8% (w/w) PEG 3350, 10% (w/w) phosphate pH 6 and 15% (w/w) NaCl. A recovery yield of 101+/-7%, a purity of 99+/-0% and a yield of native IgG of 97+/-4% were obtained. Back extraction studies of IgG to a new phosphate phase were performed and higher yields were obtained using 10% phosphate buffer at pH 6. The total extraction yield was 76% and the purity 100%. |
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Address |
IBB Institute for Biotechnology and Bioengineering, Centre for Biological and Chemical Engineering, Instituto Superior Tecnico, Av Rovisco Pais, 1049-001 Lisbon, Portugal |
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English |
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0021-9673 |
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Notes |
PMID:17196214 |
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no |
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Call Number |
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Serial |
1842 |
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