Watts, D. J., & Strogatz, S. H. (1998). Collective dynamics of /`small-world/' networks. Nature, 393(6684), 440–442.
Abstract: Networks of coupled dynamical systems have been used to model biological oscillators Josephson junction arrays excitable media, neural networks spatial games11, genetic control networks12 and many other self-organizing systems. Ordinarily, the connection topology is assumed to be either completely regular or completely random. But many biological, technological and social networks lie somewhere between these two extremes. Here we explore simple models of networks that can be tuned through this middle ground: regular networks 'rewired' to introduce increasing amounts of disorder. We find that these systems can be highly clustered, like regular lattices, yet have small characteristic path lengths, like random graphs. We call them 'small-world' networks, by analogy with the small-world phenomenon (popularly known as six degrees of separation). The neural network of the worm Caenorhabditis elegans, the power grid of the western United States, and the collaboration graph of film actors are shown to be small-world networks. Models of dynamical systems with small-world coupling display enhanced signal-propagation speed, computational power, and synchronizability. In particular, infectious diseases spread more easily in small-world networks than in regular lattices.
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Dugatkin, L. A. (1998). Breaking up fights between others: a model of intervention behaviour. Proc. R. Soc. Lond. B, 265(1394), 433–437.
Abstract: To examine when and why animals break up fights between others in their group, I modelled whether ‘winner’ and ‘loser’ effects might be one element driving the evolution of intervention behaviour. I considered one particular type of intervention: when the intervener simply breaks up fights between two others, but does not favour either party in so doing. When victories at time T + 1 are more likely given a victory at time T (i.e. winner effects), intervention is often favoured. Intervention is favoured in these circumstances because the intervening party in essence stops others from ‘getting on a roll’ and climbing up any hierarchy that exists. However, when loser effects alone are at work (defeats at time T + 1 are more likely given a defeat at time T), breaking up fights between others is never selected. If both winner and loser effects are operating simultaneously, then the likelihood of intervention behaviour evolving is a function of the relative strength of these two effects. The greater the winner effect relative to the loser effect, the more likely intervention behaviour is to evolve.
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Cox, G., & Ashford, T. (1998). Riddle Me This: The Craft and Concept of Animal Mind. Science Technology Human Values, 23(4), 425–438.
Abstract: This article examines the relations between methods used in both animal work and study and concepts of animal mind. By “animal work” the authors mean humans and animals working together, and by “animal study” they mean the discipline of ethology, especially the emerging area of cognitive ethology. Within these areas the wide range of conceptions of animal mind includes varying emphases on intelligence, forms of rationality and language, cognition, consciousness, and intentionality. The authors' central concern is to elucidate the vocabulary and the concepts which seem necessary to establishing successful working relationships with sheepdogs and gundogs. Their argument moves toward an emphasis on the appreciation of particular intentional states and recognizes that they invariably deploy elements of a moral vocabulary in achieving creative teamwork performances with dogs and other animals. The article concludes by consid enng the relevance of accounts of work with animals for associated considerations of intentionality.
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Alexander, S. L., & Irvine, C. H. (1998). The effect of social stress on adrenal axis activity in horses: the importance of monitoring corticosteroid-binding globulin capacity. Journal of Endocrinology, 157(3), 425–432.
Abstract: Plasma cortisol is largely bound to corticosteroid-binding globulin (CBG), which regulates its bioavailability by restricting exit from capillaries. Levels of CBG may be altered by several factors including stress and this can influence the amount of cortisol reaching cells. This study investigated the effect of social instability on plasma concentrations of CBG, total and free (not protein bound) cortisol in horses. Horses new to our research herd ('newcomers') were confined in a small yard with four dominant resident horses for 3-4 h daily for 3-4 (n = 5) or 9-14 (n = 3) days. Jugular blood was collected in the mornings from newcomers before the period of stress began ('pre-stress'), and then before each day's stress. Residents were bled before stress on the first and thirteenth day. Residents always behaved aggressively towards newcomers. By the end of the stress period, all newcomers were subordinate to residents. In newcomers (n = 8) after 3-4 days of social stress, CBG binding capacity had fallen (P = 0.0025), while free cortisol concentrations had risen (P = 0.0016) from pre-stress values. In contrast, total cortisol did not change. In residents, CBG had decreased slightly but significantly (P = 0.0162) after 12 days of stress. Residents and newcomers did not differ in pre-stress CBG binding capacity, total or free cortisol concentrations. However, by the second week of stress, CBG binding capacity was lower (P = 0.015) and free cortisol higher (P = 0.030) in newcomers (n = 3) than in residents. Total cortisol did not differ between the groups. In conclusion social stress clearly affected the adrenal axis of subordinate newcomer horses, lowering the binding capacity of CBG and raising free cortisol concentrations. However, no effect of stress could be detected when only total cortisol was measured. Therefore, to assess adrenal axis status accurately in horses, it is essential to monitor the binding capacity of CBG and free cortisol concentrations in addition to total cortisol levels.
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Bürger, U. (1998). The Way to perfect Horsemanship. Trafalgar Square Publishing.
Abstract: The Way to Perfect Horsemanship is an outstanding work in the vast literature devoted to horsemanship. It provides, for the first time, a clear insight into the psychological makeup of the horse, its muscular system, the mechanics of its movement, and the aids to human-to-horse communication. Udo Burger presents his philosophy of riding in a scientific manner, asserting that no one can no more learn to ride without a knowledge of horse physiology and psychology than one can learn the art of medecine without a background in health and disease. He clearly explains what one should feel and do on horseback--ultimately, as if one is part of the horse, completely united with it in all of its movements. Anyone with a genuine empathy for horses--wether teacher, trainer, competitor, or occasional rider--will benefit enormously from reading this classic work on horsemanship. The late Udo Burger was an accomplished horseman and one of Germany's most esteemed equine veterinarians.
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Schooening, B. (1998). Ethology of the horse. Prakt. Tierarzt, 79(6 Suppl.), 25–28.
Abstract: The paper starts with a short introduction/definition about ethology and the used methods in this scientific field, giving special examples for horses and about how their “normal behaviour” is measured. The behaviour repertoire of horses is described in a brief outline with special emphasis on their social systems and hierarchies and the problem of dominance, especially in interaction with humans. Schlütersche GmbH & Co. KG, Verlag und Druckerei.
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Kesel, L., & Neil, D. H. (1998). Restraint and handling of animals. Clinical Textbook for Veterinary Technicians. 4th ed., , 1–26.
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Luescher, U. A., McKeown, D. B., & Dean, H. (1998). A cross-sectional study on compulsive behaviour (stable vices) in horses. Equine veterinary journal. Supplement, (27), 14–18.
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Gatta, D., Baragli, P., Ferrarini, N., Ciattini, F., Sighieri, C., & Colombani, B. (1998). Fitness evaluation in endurance horses by standardised exercise test on treadmill. Valutazione dello stato di allenamento del cavallo da endurance mediante test standardizzato su trea, 9(4), 57–69.
Abstract: Endurance horses, like marathon runners, undertake sub-maximal, longterm physical exercises and in both cases thermoregulation plays a critical role. A standardised sub-maximal treadmill test was used to assess fitness and training state in endurance horses. Literature reports that trained human athletes dissipate head load better than not trained ones; in this study parameters related to thermoregulation were recorded together with other haematologic and metabolic ones. Six endurance horses, divided into two groups according to their training state, performed two submaximal tests at a distance of one week. Blood samples were collected at rest, during exercise, at the end and during recovery (10, 30 and 60 minutes after work). Heart rate (HR), respiratory rate (RR), rectal (RT) and skin (ST) temperatures were monitored through the exercise (and recovery for HR). HR resulted significantly lower (P<0.01) in trained horses than in untrained ones, especially during recovery. Also rectal and skin temperatures resulted significantly lower (P<0.05) in trained horses and ST increased more gradually during exercise. The values of haematocrit and haemoglobin resulted significantly lower (P<0.05) at rest, during exercise and recovery samples. In this study, the parameters related to thermoregulation, in accordance with data from human athletes, resulted significantly different in trained and untrained horses, while other parameters didn't vary significantly between the two groups. Thermoregulatory responses to exercise-generated heat load in a standardised test, studied by simple parameters, can thus offer useful information about fitness and training state of endurance horses.
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Redbo, I., Redbo-Torstensson, P., Ödberg, F. O., Hedendahl, A., & Holm, J. (1998). Factors affecting behavioural disturbances in race-horses. Animal Science, 66(2), 475–481.
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