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Author |
Suzuki, Y.; Toquenaga, Y. |
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Title |
Effects of information and group structure on evolution of altruism: analysis of two-score model by covariance and contextual analyses |
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Journal Article |
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Year |
2005 |
Publication |
Journal of theoretical biology |
Abbreviated Journal  |
J. Theor. Biol. |
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Volume |
232 |
Issue |
2 |
Pages |
191-201 |
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*Altruism; Analysis of Variance; *Communication; Cooperative Behavior; *Evolution; Game Theory; *Group Structure; Humans; Models, Genetic; Models, Psychological; Selection (Genetics); Trust |
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Abstract |
An altruistic individual has to gamble on cooperation to a stranger because it does not know whether the stranger is trustworthy before direct interaction. Nowak and Sigmund (Nature 393 (1998a) 573; J. Theor. Biol. 194 (1998b) 561) presented a new theoretical framework of indirect reciprocal altruism by image scoring game where all individuals are informed about a partner's behavior from its image score without direct interaction. Interestingly, in a simplified version of the image scoring game, the evolutionarily stability condition for altruism became a similar form of Hamilton's rule, i.e. inequality that the probability of getting correct information is more than the ratio of cost to benefit. Since the Hamilton's rule was derived by evolutionarily stable analysis, the evolutionary meaning of the probability of getting correct information has not been clearly examined in terms of kin and group selection. In this study, we applied covariance analysis to the two-score model for deriving the Hamilton's rule. We confirmed that the probability of getting correct information was proportional to the bias of altruistic interactions caused by using information about a partner's image score. The Hamilton's rule was dependent on the number of game bouts even though the information reduced the risk of cooperation to selfish one at the first encounter. In addition, we incorporated group structure to the two-score model to examine whether the probability of getting correct information affect selection for altruism by group selection. We calculated a Hamilton's rule of group selection by contextual analysis. Group selection is very effective when either the probability of getting correct information or that of future interaction, or both are low. The two Hamilton's rules derived by covariance and contextual analyses demonstrated the effects of information and group structure on the evolution of altruism. We inferred that information about a partner's behavior and group structure can produce flexible pathways for the evolution of altruism. |
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Integrative Environmental Sciences, Graduate School of Life and Environmental Sciences, University of Tsukuba, 1-1-1, Ten-Nou-Dai, Tsukuba, Ibaraki 305-8572, Japan. yukari@pe.ies.life.tsukuba.ac.jp |
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0022-5193 |
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PMID:15530489 |
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refbase @ user @ |
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556 |
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Author |
Paz-y-Miño C. G.; Bond, A.B.; Kamil, A.C.; Balda, R.P. |
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Title |
Pinyon jays use transitive inference to predict social dominance |
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Journal Article |
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Year |
2004 |
Publication |
Nature |
Abbreviated Journal |
Nature |
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Volume |
430 |
Issue |
7001 |
Pages |
778-781 |
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Keywords |
Animals; Cognition/*physiology; Group Structure; Male; *Social Dominance; Songbirds/*physiology |
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Living in large, stable social groups is often considered to favour the evolution of enhanced cognitive abilities, such as recognizing group members, tracking their social status and inferring relationships among them. An individual's place in the social order can be learned through direct interactions with others, but conflicts can be time-consuming and even injurious. Because the number of possible pairwise interactions increases rapidly with group size, members of large social groups will benefit if they can make judgments about relationships on the basis of indirect evidence. Transitive reasoning should therefore be particularly important for social individuals, allowing assessment of relationships from observations of interactions among others. Although a variety of studies have suggested that transitive inference may be used in social settings, the phenomenon has not been demonstrated under controlled conditions in animals. Here we show that highly social pinyon jays (Gymnorhinus cyanocephalus) draw sophisticated inferences about their own dominance status relative to that of strangers that they have observed interacting with known individuals. These results directly demonstrate that animals use transitive inference in social settings and imply that such cognitive capabilities are widespread among social species. |
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Center for Avian Cognition, School of Biological Sciences, University of Nebraska, Lincoln, Nebraska 68588, USA |
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1476-4687 |
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PMID:15306809 |
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refbase @ user @; Equine Behaviour @ team @ room B 3.029 |
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352 |
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Author |
Shettleworth, S.J. |
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Title |
Cognitive science: rank inferred by reason |
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Journal Article |
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Year |
2004 |
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Nature |
Abbreviated Journal |
Nature |
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430 |
Issue |
7001 |
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732-733 |
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Animals; Cognition/*physiology; Group Structure; Male; *Social Dominance; Songbirds/*physiology |
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1476-4687 |
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PMID:15306792 |
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refbase @ user @ |
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365 |
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Author |
Conradt, L.; Roper, T.J. |
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Title |
Group decision-making in animals |
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Journal Article |
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Year |
2003 |
Publication |
Nature |
Abbreviated Journal |
Nature |
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Volume |
421 |
Issue |
6919 |
Pages |
155-158 |
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Keywords |
Animals; Behavior, Animal/*physiology; *Decision Making; Democracy; Group Processes; *Models, Biological; Population Density; Social Behavior |
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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. |
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School of Biological Sciences, University of Sussex, Brighton BN1 9QG, UK. l.conradt@sussex.ac.uk |
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0028-0836 |
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PMID:12520299 |
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Equine Behaviour @ team @ |
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5136 |
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Author |
Valone, T.J. |
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Title |
Group foraging, public information, and patch estimation |
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Journal Article |
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Year |
1989 |
Publication |
Oikos |
Abbreviated Journal |
Oikos |
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56 |
Issue |
3 |
Pages |
357-363 |
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Keywords |
Techniques; Mathematical techniques; Nutrition; Feeding behaviour; Behaviour; Social behaviour^, Comprehensive Zoology; Mathematical model; Resource patch estimation by group members; use of public information; Foraging; Group behaviour |
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Public information is information about the quality of a patch that can be obtained by observing the foraging success of other individuals in that patch. I examine the influence of the use of public information on patch departure and foraging efficiency of group members. When groups depart a patch with the first individual to leave, the use of public information can prevent the underutilization of resource patches. |
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Equine Behaviour @ team @ |
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4274 |
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Author |
Dyer, J.R.G.; Johansson, A.; Helbing, D.; Couzin, I.D.; Krause, J. |
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Title |
Leadership, consensus decision making and collective behaviour in humans |
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Journal Article |
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2009 |
Publication |
Philosophical Transactions of the Royal Society B: Biological Sciences |
Abbreviated Journal |
Phil. Trans. Biol. Sci. |
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364 |
Issue |
1518 |
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781-789 |
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* leadership * consensus decision making * collective behaviour * human group |
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This paper reviews the literature on leadership in vertebrate groups, including recent work on human groups, before presenting the results of three new experiments looking at leadership and decision making in small and large human groups. In experiment 1, we find that both group size and the presence of uninformed individuals can affect the speed with which small human groups (eight people) decide between two opposing directional preferences and the likelihood of the group splitting. In experiment 2, we show that the spatial positioning of informed individuals within small human groups (10 people) can affect the speed and accuracy of group motion. We find that having a mixture of leaders positioned in the centre and on the edge of a group increases the speed and accuracy with which the group reaches their target. In experiment 3, we use large human crowds (100 and 200 people) to demonstrate that the trends observed from earlier work using small human groups can be applied to larger crowds. We find that only a small minority of informed individuals is needed to guide a large uninformed group. These studies build upon important theoretical and empirical work on leadership and decision making in animal groups. |
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Equine Behaviour @ team @ |
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5122 |
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Author |
Wolter, R.; Pantel, N.; Stefanski, V.; Möstl, E.; Krueger, K. |
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Title |
The role of an alpha animal in changing environmental conditions |
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Journal Article |
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2014 |
Publication |
Physiology & Behavior |
Abbreviated Journal |
Physiol. Behav. |
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133 |
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236-243 |
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Alpha male; Horse; Equus ferus przewalskii; Bachelor group; Group structure |
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Abstract The maintenance and development of conservation areas by grazing of large herbivores, such as Przewalski's horses, is common practice. Several nature conservation areas house male bachelor groups of this species. When males are needed for breeding they are removed from the groups, often without considering group compositions and individual social positions. However, alpha animals are needed for ensuring group stability and decision making in potentially dangerous situations in several species. To investigate the role of the alpha male in a bachelor group, we observed the behaviour of five Przewalski's horse males during the enlargement of their enclosure. We analyzed the group's social structure and movement orders, as well as the animals' connectedness, activity budgets, and whether they moved with preferred group members and how factors such as social rank influenced the horses' behaviour. We also investigated the excretion of glucocorticoid metabolites (GCM) via faeces of the horses while exploring a new area as a parameter of glucocorticoid production. Our results show that the alpha male is important for a bachelor group in changing environmental conditions. The alpha male had the highest level of connectedness within the group. When exploring the new environment, its position in the group changed from previously being the last to being the first. Furthermore the whole group behaviour changed when exploring the new area. The stallions showed reduced resting behavior, increased feeding and did not stay close to each other. We found that the excretion of glucocorticoid metabolites of most horses rose only marginally during the first days on the new area while only the alpha male showed a significant increased amount of glucocorticoid production during the first day of the enclosure enlargement. |
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0031-9384 |
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Equine Behaviour @ team @ |
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5818 |
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Author |
Sawaguchi, T.; Kudo, H. |
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Title |
Neocortical development and social structure in primates |
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Year |
1990 |
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Primates |
Abbreviated Journal |
Primates |
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31 |
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2 |
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283-289 |
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Neocortex – Relative size – Allometry – Congeneric group – Social structure – Monogyny – Polygyny – Primates |
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Abstract  The relationships between the relative size of the neocortex and differences in social structures were examined in prosimians and anthropoids. The relative size of the neocortex (RSN) of a given congeneric group in each superfamily of primates was measured based on the allometric relationships between neocortical volume and brain weight for each superfamily, to control phylogenetic affinity and the effects of brain size. In prosimians, “troop-making†congeneric groups (N=3) revealed a significantly larger RSN than solitary groups (N=6), and there was a significant, positive correlation between RSN and troop size. In the case of anthropoids, polygynous/frugivorous groups (N=5) revealed a significantly larger RSN than monogynous/frugivorous groups (N=8). Furthermore, a significant, positive correlation between RSN and troop size was found for frugivorous congeneric groups of the Ceboidea. These results suggest that neocortical development is associated with differences in social structure among primates. |
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Equine Behaviour @ team @ |
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4799 |
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Author |
Brosnan, S.F.; Schiff, H.C.; de Waal, F.B.M. |
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Title |
Tolerance for inequity may increase with social closeness in chimpanzees |
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Journal Article |
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Year |
2005 |
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Proceedings. Biological sciences / The Royal Society |
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Proc Biol Sci |
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272 |
Issue |
1560 |
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253-258 |
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Analysis of Variance; Animals; *Attitude; Group Processes; Pan troglodytes/*psychology; Reward; *Social Behavior; Socioeconomic Factors |
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Economic decision-making depends on our social environment. Humans tend to respond differently to inequity in close relationships, yet we know little about the potential for such variation in other species. We examine responses to inequity in several groups of chimpanzees (Pan troglodytes) in a paradigm similar to that used previously in capuchin monkeys (Cebus apella). We demonstrate that, like capuchin monkeys, chimpanzees show a response to inequity of rewards that is based upon the partner receiving the reward rather than the presence of the reward alone. However, we also found a great amount of variation between groups tested, indicating that chimpanzees, like people, respond to inequity in a variable manner, which we speculate could be caused by such variables as group size, the social closeness of the group (as reflected in length of time that the group has been together) and group-specific traditions. |
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Yerkes National Primate Research Center, Emory University, 954 North Gatewood Drive, Atlanta, GA 30329, USA. sbrosna@emory.edu |
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0962-8452 |
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PMID:15705549 |
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refbase @ user @ |
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169 |
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Zhou, W.-X.; Sornette, D.; Hill, R.A.; Dunbar, R.I.M. |
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Discrete hierarchical organization of social group sizes |
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Journal Article |
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2005 |
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Proceedings. Biological sciences / The Royal Society |
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Proc Biol Sci |
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272 |
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1561 |
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439-444 |
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Anthropology, Cultural; *Group Structure; Humans; *Models, Biological; *Social Behavior; *Social Environment |
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The 'social brain hypothesis' for the evolution of large brains in primates has led to evidence for the coevolution of neocortical size and social group sizes, suggesting that there is a cognitive constraint on group size that depends, in some way, on the volume of neural material available for processing and synthesizing information on social relationships. More recently, work on both human and non-human primates has suggested that social groups are often hierarchically structured. We combine data on human grouping patterns in a comprehensive and systematic study. Using fractal analysis, we identify, with high statistical confidence, a discrete hierarchy of group sizes with a preferred scaling ratio close to three: rather than a single or a continuous spectrum of group sizes, humans spontaneously form groups of preferred sizes organized in a geometrical series approximating 3-5, 9-15, 30-45, etc. Such discrete scale invariance could be related to that identified in signatures of herding behaviour in financial markets and might reflect a hierarchical processing of social nearness by human brains. |
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State Key Laboratory of Chemical Reaction Engineering, East China University of Science and Technology, Shanghai 200237, China |
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0962-8452 |
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PMID:15734699 |
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refbase @ user @ |
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549 |
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