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Author Wilson, A.M.; McGuigan, M.P.; Su, A.; van Den Bogert, A.J.
Title Horses damp the spring in their step Type Journal Article
Year 2001 Publication Nature Abbreviated Journal Nature
Volume 414 Issue 6866 Pages 895-899
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
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.
Address Department of Veterinary Basic Sciences, The Royal Veterinary College, Hatfield, Herts AL9 7TA, UK. awilson@rvc.ac.uk
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Series Volume Series Issue Edition
ISSN 0028-0836 ISBN Medium
Area Expedition Conference
Notes (up) PMID:11780059 Approved no
Call Number Equine Behaviour @ team @ Serial 2300
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Author Dyer, F.C.
Title Animal behaviour: when it pays to waggle Type
Year 2002 Publication Nature Abbreviated Journal Nature
Volume 419 Issue 6910 Pages 885-886
Keywords *Animal Communication; Animals; Bees/*physiology; California; Dancing/physiology; Environment; Evolution; Female; Flowers/chemistry; *Food; Gravitation; Lighting; Motor Activity/*physiology; Odors; Seasons; Sunlight
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ISSN 0028-0836 ISBN Medium
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Notes (up) PMID:12410290 Approved no
Call Number refbase @ user @ Serial 769
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Author Conradt, L.; Roper, T.J.
Title Group decision-making in animals Type Journal Article
Year 2003 Publication Nature Abbreviated Journal Nature
Volume 421 Issue 6919 Pages 155-158
Keywords Animals; Behavior, Animal/*physiology; *Decision Making; Democracy; Group Processes; *Models, Biological; Population Density; Social Behavior
Abstract Groups of animals often need to make communal decisions, for example about which activities to perform, when to perform them and which direction to travel in; however, little is known about how they do so. Here, we model the fitness consequences of two possible decision-making mechanisms: 'despotism' and 'democracy'. We show that under most conditions, the costs to subordinate group members, and to the group as a whole, are considerably higher for despotic than for democratic decisions. Even when the despot is the most experienced group member, it only pays other members to accept its decision when group size is small and the difference in information is large. Democratic decisions are more beneficial primarily because they tend to produce less extreme decisions, rather than because each individual has an influence on the decision per se. Our model suggests that democracy should be widespread and makes quantitative, testable predictions about group decision-making in non-humans.
Address School of Biological Sciences, University of Sussex, Brighton BN1 9QG, UK. l.conradt@sussex.ac.uk
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ISSN 0028-0836 ISBN Medium
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Notes (up) PMID:12520299 Approved no
Call Number Equine Behaviour @ team @ Serial 5136
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Author Johnson, D.D.P.; Stopka, P.; Knights, S.
Title Sociology: The puzzle of human cooperation Type Journal Article
Year 2003 Publication Nature Abbreviated Journal Nature
Volume 421 Issue 6926 Pages 911-2; discussion 912
Keywords Altruism; *Cooperative Behavior; Evolution; Humans; *Models, Biological; Punishment; Reward; Risk
Abstract
Address Olin Institute for Strategic Studies, Harvard University, Cambridge, Massachusetts 02138, USA. dominic@post.harvard.edu
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ISSN 0028-0836 ISBN Medium
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Notes (up) PMID:12606989 Approved no
Call Number refbase @ user @ Serial 467
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Author Adolphs, R.
Title Cognitive neuroscience of human social behaviour Type Journal Article
Year 2003 Publication Nature Reviews. Neuroscience Abbreviated Journal Nat Rev Neurosci
Volume 4 Issue 3 Pages 165-178
Keywords Cognition; Emotions; Humans; Models, Psychological; *Social Behavior
Abstract We are an intensely social species--it has been argued that our social nature defines what makes us human, what makes us conscious or what gave us our large brains. As a new field, the social brain sciences are probing the neural underpinnings of social behaviour and have produced a banquet of data that are both tantalizing and deeply puzzling. We are finding new links between emotion and reason, between action and perception, and between representations of other people and ourselves. No less important are the links that are also being established across disciplines to understand social behaviour, as neuroscientists, social psychologists, anthropologists, ethologists and philosophers forge new collaborations.
Address Deparment of Neurology, University of Iowa, 200 Hawkins Drive, Iowa City, Iowa 52242, USA. ralph-adolphs@uiowa.edu
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Series Volume Series Issue Edition
ISSN 1471-003X ISBN Medium
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Notes (up) PMID:12612630 Approved no
Call Number Equine Behaviour @ team @ Serial 4706
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Author Rands, S.A.; Cowlishaw, G.; Pettifor, R.A.; Rowcliffe, J.M.; Johnstone, R.A.
Title Spontaneous emergence of leaders and followers in foraging pairs Type Journal Article
Year 2003 Publication Nature Abbreviated Journal Nature
Volume 423 Issue 6938 Pages 432-434
Keywords Animals; *Energy Metabolism; Food; *Food Chain; *Models, Biological; Motor Activity; *Social Behavior; Time Factors
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.
Address Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK. s.rands@zoo.cam.ac.uk
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ISSN 0028-0836 ISBN Medium
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Notes (up) PMID:12761547 Approved no
Call Number Equine Behaviour @ team @ Serial 5138
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Author Alexander, F.; Chowdhury, A.K.
Title Enzymes in the ileal juice of the horse Type Journal Article
Year 1958 Publication Nature Abbreviated Journal Nature
Volume 181 Issue 4603 Pages 190
Keywords *Enzymes; *Horses; Ileum/*metabolism; *Enzymes; *Horses; *ILEUM/metabolism
Abstract
Address
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ISSN 0028-0836 ISBN Medium
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Notes (up) PMID:13504127 Approved no
Call Number refbase @ user @ Serial 121
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Author Brosnan, S.F.; De Waal, F.B.M.
Title Monkeys reject unequal pay Type Journal Article
Year 2003 Publication Nature Abbreviated Journal Nature
Volume 425 Issue 6955 Pages 297-299
Keywords Aging; Animals; Cebus/*psychology; Choice Behavior; *Cooperative Behavior; Female; Male; *Reward; Social Justice
Abstract During the evolution of cooperation it may have become critical for individuals to compare their own efforts and pay-offs with those of others. Negative reactions may occur when expectations are violated. One theory proposes that aversion to inequity can explain human cooperation within the bounds of the rational choice model, and may in fact be more inclusive than previous explanations. Although there exists substantial cultural variation in its particulars, this 'sense of fairness' is probably a human universal that has been shown to prevail in a wide variety of circumstances. However, we are not the only cooperative animals, hence inequity aversion may not be uniquely human. Many highly cooperative nonhuman species seem guided by a set of expectations about the outcome of cooperation and the division of resources. Here we demonstrate that a nonhuman primate, the brown capuchin monkey (Cebus apella), responds negatively to unequal reward distribution in exchanges with a human experimenter. Monkeys refused to participate if they witnessed a conspecific obtain a more attractive reward for equal effort, an effect amplified if the partner received such a reward without any effort at all. These reactions support an early evolutionary origin of inequity aversion.
Address Living Links, Yerkes National Primate Research Center, Emory University, Atlanta, Georgia 30329, USA. sbrosna@emory.edu
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Series Volume Series Issue Edition
ISSN 1476-4687 ISBN Medium
Area Expedition Conference
Notes (up) PMID:13679918 Approved no
Call Number refbase @ user @ Serial 179
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Author Proudman, C.; Pinchbeck, G.; Clegg, P.; French, N.
Title Equine welfare: risk of horses falling in the Grand National Type Journal Article
Year 2004 Publication Nature Abbreviated Journal Nature
Volume 428 Issue 6981 Pages 385-386
Keywords Accidental Falls/prevention & control/*statistics & numerical data; Animal Welfare; Animals; Great Britain; Horse Diseases/prevention & control; Horses/*physiology; Odds Ratio; Risk Assessment; *Sports
Abstract As in other competitive sports, the famous Grand National steeplechase, which is held at Aintree in the United Kingdom and is watched by 600 million people worldwide, sometimes results in injury. By analysing data from the past 15 Grand National races (consisting of 560 starts by horses), we are able to identify several factors that are significantly associated with failure to complete the race: no previous experience of the course and its unique obstacles, unfavourable ground conditions (too soft or too hard), a large number of runners, and the length of the odds ('starting price'). We also find that there is an increased risk of falling at the first fence and at the jump known as Becher's Brook, which has a ditch on the landing side. Our findings indicate ways in which the Grand National could be made safer for horses and illustrate how epidemiological analysis might contribute to preventing injury in competitive sport.
Address Epidemiology Group, Faculty of Veterinary Science, University of Liverpool, Leahurst, Neston, Wirral CH64 7TE, UK. c.j.proudman@liverpool.ac.uk
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ISSN 1476-4687 ISBN Medium
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Notes (up) PMID:15042079 Approved no
Call Number refbase @ user @ Serial 535
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Author Harman, F.S.; Nicol, C.J.; Marin, H.E.; Ward, J.M.; Gonzalez, F.J.; Peters, J.M.
Title Peroxisome proliferator-activated receptor-delta attenuates colon carcinogenesis Type Journal Article
Year 2004 Publication Nature medicine Abbreviated Journal Nat Med
Volume 10 Issue 5 Pages 481-483
Keywords Animals; Azoxymethane/toxicity; Colonic Neoplasms/etiology/genetics/*prevention & control; Colonic Polyps/etiology/genetics/pathology/prevention & control; Disease Models, Animal; Mice; Mice, Knockout; Mice, Mutant Strains; Phenotype; Receptors, Cytoplasmic and Nuclear/deficiency/genetics/*physiology; Transcription Factors/deficiency/genetics/*physiology
Abstract Peroxisome proliferator-activated receptor-delta (PPAR-delta; also known as PPAR-beta) is expressed at high levels in colon tumors, but its contribution to colon cancer is unclear. We examined the role of PPAR-delta in colon carcinogenesis using PPAR-delta-deficient (Ppard(-/-)) mice. In both the Min mutant and chemically induced mouse models, colon polyp formation was significantly greater in mice nullizygous for PPAR-delta. In contrast to previous reports suggesting that activation of PPAR-delta potentiates colon polyp formation, here we show that PPAR-delta attenuates colon carcinogenesis.
Address Department of Veterinary Science and The Center for Molecular Toxicology and Carcinogenesis, The Pennsylvania State University, University Park, Pennsylvania 16802, USA. jmp21@psu.edu
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Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1078-8956 ISBN Medium
Area Expedition Conference
Notes (up) PMID:15048110 Approved no
Call Number refbase @ user @ Serial 77
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