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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
111

Understanding of human communicative motives in domestic dogs

Pettersson, Helene January 2009 (has links)
I investigated the understanding of human communicative motives in domestic dogs. Dogs use human communicative cues, like the pointing gesture when searching for hidden food, but it is uncertain how dogs interpret human communication. 32 dogs were presented with two communicative contexts in an object choice task experimental design. In a cooperative context the experimenter informed the subject where food was hidden by pointing and giving a verbal indication. In a competitive context the experimenter held out her arm towards the correct location in a stop gesture and firmly said no. To be successful in the competitive context the subject had to understand the experimenters communicative motive and make an inference from the prohibition (i.e. she would only prohibit it if there was something good there). The average correct choices were compared between the conditions. The dogs successfully followed the cooperative communication. They showed a trend towards choosing the baited cup in the competitive condition. A second study tested if the stop gesture affected the dogs’ choice, since it is not known how dogs interpret gestures. The pointing cue was now presented with the prohibiting command and the stop gesture was presented with the cooperative verbal cue. The dogs used the cooperative communication but did not understand the competitive context. A difference between the contexts was found. The dogs did not differentiate between the gestures. In conclusion dogs do not make inferences from competitive communication or prohibition but are specialized in utilizing cooperative communication
112

Do enclosure characteristics affect anti-predator behaviour in the European bison (Bison bonasus)?

Hofling, Annika January 2009 (has links)
Animals raised in captivity often fail to express appropriate anti-predator behaviour when reintroduced into the wild. The European bison (Bison bonasus) is a species that was close to extinction in the early 20th century but was saved in the last moment by intense captive breeding and subsequent reintroduction into the wild. In this study, seven groups of European bison living in different locations in Sweden were studied to investigate whether there was any difference in the anti-predator behaviour depending on the type of enclosure they were kept in. Olfactory and auditory stimuli from moose, as a control, and from two predators, wolf and bear, and visual stimulus (silhouette of a wolf) were presented to the animals and their response to them and behaviour following presentation were analysed. The results showed that European bison kept in barren enclosures responded stronger to auditory stimuli than those that were kept in naturalistic enclosures. The results further showed that the animals had a stronger response to the visual stimulus than to the auditory stimuli. The animals changed their behaviour after stimuli presentations compared to a pre-test baseline. They moved, stood still and ate for a significantly longer period of time and they rested for a shorter period of time after being presented olfactory, auditory and visual stimuli than during pre-test baseline.
113

Living with males : benefits and costs to females of resident males in Colobus vellerosus

Hedlund, Johanna S. U. January 2009 (has links)
Only in primates is permanent male-female association the most widespread social structure of all. The continuous presence of resident males in the social group can have significant impacts on female fitness, both in forms of costs and benefits. In this study I investigate particular short-term benefits and costs of resident males to females in a population of ursine colobus (Colobus vellerosus). I hypothesise that for females permanent association with males result in certain benefits and certain costs, exceeding those provided or imposed by other females. The results indicate that female derive greater benefits from males than from females during intergroup encounters and in the form of vigilance since males were the main participants in intergroup encounter and were more vigilant than females. I could not confirm any type of behaviour employed by resident males that is costly to females. However, the rarity and subtleness of some costly male behaviours imply that more data is needed before making a conclusion on their absence or occurrence in this population and I purpose that herding behaviour could occur at my study site. Moreover, multi-male groups (MM-groups) showed higher rates of vigilance than single-male groups (SM-groups) and had a tendency to experiencing fewer intergroup encounters than SM-groups. I interpret the former as a result of the demanding social conditions in the MM-groups. The latter indicate that females may benefit from MM-group living through a decrease in intergroup encounters.
114

Olfactory sensitivity of spider monkeys (Ateles geoffroyi) for six structurally related aromatic aldehydes

Kjelmand, Luna January 2009 (has links)
For many years, primates have been considered to be animals with a poorly developed sense of smell. However, in recent years several studies have shown that at least some primate species have a high olfactory sensitivity for a variety of odorants. The present study used a two-choice instrumental conditioning paradigm to test the olfactory sensitivity for six aromatic aldehydes in four spider monkeys (Ateles geoffroyi). With helional, cyclamal,canthoxal and lilial all animals discriminated concentrations below 1 ppm from the odorless solvent, with single individuals even scoring better. With 3-phenyl-propionic aldehyde all animals detected concentrations below 2 ppb, and with bourgeonal even below 0.3 ppb. The detection thresholds of the odorants changed systematically with molecular structure. Addition of a dioxo or methoxy group to the benzene ring led to an increase in threshold values,while the absence of a methyl group close to the aldehyde moiety was linked to a low threshold value for the odorant. The study shows that spider monkeys have a well developed olfactory sensitivity for aromatic aldehydes.
115

Factors Influencing Web Tenure in a Tropical Spider and Comparison between Forest and Non-forest Habitats

Barraza, Daniella R 01 December 2012 (has links)
Webs are fundamental to the ecology of Nephila clavipes, the golden orb-weaver spider, because they serve as sites for prey capture, reproduction, competition, predation, and parasitism. In addition to the presence of the female N. clavipes, males and kleptoparasites reside on the web in varying numbers. Webs are also found in clusters with conspecific females. Web site selection and length of web tenure is a behavioral decision vital to the spider’s fitness and the ecology of her species. I conducted a field census to quantify these factors and analyze their influence on web tenure, compare web ecology between a forest and non-forest habitat, as well as explain the significance of N. clavipes’ web as central to many interactions. Web tenure, as well, was influenced differently by the factors between both environments. In the forest habitat, increase in prey capture rate decreased web tenure and inclusion in cluster increased web tenure. In the non-forest habitat, only increase in spider size was related to increased web tenure. There were significant differences between the two habitats in the sizes of the female spider and quantity of males and kleptoparasites. Results also showed that spider size influenced quantity of males and web diameter influenced quantity of kleptoparasites. Explanation of these results can be attributed to the complex relationships among the variables and the consequences of living in habitats impacted by human occupation.
116

Next Generation Sequencing Reveals Gene Expression Patterns in the Zebrafish Inner Ear Following Growth Hormone Injection

Rajadinakaran, Gopinath 01 August 2012 (has links)
Loss of hair cells due to acoustic trauma results in the loss of hearing. In humans, unlike other vertebrates, the mechanism of hair cell regeneration is not possible. The molecular mechanisms that underlie this regeneration in nonmammalian vertebrates remain elusive. To understand the gene regulation during hair cell regeneration, our previous microarray study on zebrafish inner ears found that growth hormone (GH) was significantly upregulated after noise exposure. In this current study, we utilized Next Generation Sequencing (NGS) to examine the genes and pathways that are significantly regulated in the zebrafish inner ear following sound exposure and GH injection. Four groups of 20 zebrafish each were exposed to a 150 Hz tone at 179 dB re 1μPa RMS for 40 h. Zebrafish were injected with either salmon GH, phosphate buffer or zebrafish GH antagonist following acoustic exposure, and one baseline group received no acoustic stimulus or injection. RNA was extracted from ear tissues at 1 and 2 days post-trauma, and cDNA was synthesized for NGS. The reads from Illumina Pipeline version SCS 2.8.0 were aligned using TopHat and annotated using Cufflinks. The statistically significant differentially expressed transcripts were identified using Cuffdiff for six different pairwise comparisons and were analyzed using Ingenuity Pathway Analysis. I found significant regulation of growth factors such as GH, prolactin and fibroblast growth factor receptor 2, different families of solute carrier molecules, cell adhesion molecules such as CDH17 and CDH23, and other transcription factors such as Fos, FosB, Jun that regulate apoptosis. Analysis of the cell proliferation network in the GH-injected condition compared to buffer-injected day 1 showed significant up-regulation of GH while downregulation of apoptotic transcription factors was found. In contrast, the antagonist-injected condition compared to the GH-injected condition showed an opposite pattern in which up-regulation of apoptotic transcription factors were found while GH was down-regulated. A number of other transcripts (e.g., POMC, SLC6A12, TMEM27, HNF4A, CDH17 and FGFR2) that showed up-regulation in GH-injected condition showed down-regulation in antagonist-injected condition. These results strongly suggest that injection of exogenous GH potentially has a protective role in the zebrafish inner ear following acoustic trauma.
117

Learning with ALiCE II

Lockery, Daniel Alexander 14 September 2007 (has links)
The problem considered in this thesis is the development of an autonomous prototype robot capable of gathering sensory information from its environment allowing it to provide feedback on the condition of specific targets to aid in maintenance of hydro equipment. The context for the solution to this problem is based on the power grid environment operated by the local hydro utility. The intent is to monitor power line structures by travelling along skywire located at the top of towers, providing a view of everything beneath it including, for example, insulators, conductors, and towers. The contribution of this thesis is a novel robot design with the potential to prevent hazardous situations and the use of rough coverage feedback modified reinforcement learning algorithms to establish behaviours. / October 2007
118

Reinforcement learning in biologically-inspired collective robotics: a rough set approach

Henry, Christopher 19 September 2006 (has links)
This thesis presents a rough set approach to reinforcement learning. This is made possible by considering behaviour patterns of learning agents in the context of approximation spaces. Rough set theory introduced by Zdzisław Pawlak in the early 1980s provides a ground for deriving pattern-based rewards within approximation spaces. Learning can be considered episodic. The framework provided by an approximation space makes it possible to derive pattern-based reference rewards at the end of each episode. Reference rewards provide a standard for reinforcement comparison as well as the actor-critic method of reinforcement learning. In addition, approximation spaces provide a basis for deriving episodic weights that provide a basis for a new form of off-policy Monte Carlo learning control method. A number of conventional and pattern-based reinforcement learning methods are investigated in this thesis. In addition, this thesis introduces two learning environments used to compare the algorithms. The first is a Monocular Vision System used to track a moving target. The second is an artificial ecosystem testbed that makes it possible to study swarm behaviour by collections of biologically-inspired bots. The simulated ecosystem has an ethological basis inspired by the work of Niko Tinbergen, who introduced in the 1960s methods of observing and explaining the behaviour of biological organisms that carry over into the study of the behaviour of interacting robotic devices that cooperate to survive and to carry out highly specialized tasks. Agent behaviour during each episode is recorded in a decision table called an ethogram, which records features such as states, proximate causes, responses (actions), action preferences, rewards and decisions (actions chosen and actions rejected). At all times an agent follows a policy that maps perceived states of the environment to actions. The goal of the learning algorithms is to find an optimal policy in a non-stationary environment. The results of the learning experiments with seven forms of reinforcement learning are given. The contribution of this thesis is a comprehensive introduction to a pattern-based evaluation of behaviour during reinforcement learning using approximation spaces. / May 2006
119

Höns återhämtning efter stress samt domesticeringens effekter : En biologisk studie med ett lärarperspektiv

Alriksson, Emelie January 2011 (has links)
Den biologiska studien har visat att värphöns genom domesticeringen förändrat och anpassat sina beteenden till att leva med människor. De har utvecklat en minskad rädsla för människor och en ökad stresstålighet. I denna studie har höns återhämtning efter en stressupplevelse studerats. För att se hur domesticeringen har påverkat återhämtningen jämfördes beteenden mellan raserna White Leghorn och red junglefowl. Frågeställningarna som användes för att undersöka detta var: Hur lång tid tar det innan höns återhämtar sina naturliga beteenden, ej stressrelaterade, efter en stressupplevelse? Finns det några skillnader i återhämtningen beroende av kön eller mellan raserna White Leghorn och red junglefowl? Resultatet visade inte på en specifik tid för återhämtning men på att en tydlig återhämtning förekom. Återhämtningen visades i beteendena Relaxed Behaviour, Comfort Behaviour, Perch, Vocalisation och Stand Alert genom att uppvisandet av beteendena skiljde sig signifikant med tiden. Även signifikanta skillnader visades mellan raserna, både i beteenden som visade på återhämtning och i beteenden som inte gjorde det. En slutsats om vilken ras som återhämtade sig snabbast var svår att dra. Detta på grund av att beteendeskillnaderna visade på olika tendenser gällande återhämtning. Skillnaderna i återhämtningen mellan könen, visades tendenser på att hanarna återhämtade sig snabbare. Domesticering har även i denna studie studerats utifrån ett lärarperspektiv. Undersökningen visade att domesticering kan ingå i biologiundervisningen i områdena evolution och genetik i år 7-9. / The biological study has shown that behaviour of laying hens has changed through domestication and the hens have adapted to live with humans. They have developed less fear of humans and more resistance to stress. In this study hens’ recovery after a stressful experience has been studied. A comparison between the breeds White Leghorn and red junglefowl has been made to see how the domestication has affected the recovery. The questions of this study are therefore: How long does it take for hens’ to recover their natural behaviour, not stressrelated, after a stressful experience? Are there any differences in recovery between the different breeds White Leghorn and red junglefowl? The results did not show a specific time for recovery, but a distinct recovery was noticed in Relaxed Behaviour, Comfort Behaviour, Perch, Vocalisation and Stand Alert. This beacause of the behaviours differed significantly with time. Also significant differences existed between the breeds, both in behaviours that showed recovery and in behavious that did not. A conclusion of what breed that recovered fastest was difficult to make. This because of the differences of behaviour showed different tendencies in recovery. The differences in recovery between the sexes showed tendencies that the males recovered fastest. The domestication has also been studied from a teacherperspective. The study showed that domestication can be a part of biologyeducation in the fields of evolution and genetics in the grades 7-9.
120

Återhämtningsförmåga efter en stressupplevelse hos röda djungelhöns (Gallus gallus) och domesticerade värphöns, White Leghorn : Ett projektförslag för ämnet biologi på gymnasiet

Hultberg, Sandra January 2011 (has links)
Många elever ser naturvetenskapliga ämnen som svåra och tappar lätt intresset om inte läraren presenterar ämnet tillfredsställande. Jean Piaget har haft stor betydelse inom pedagogiken, då han menade att intelligens är en metod som barn kan lära sig genom att utforska och laborera. Genom möjligheten att få göra en observationsstudie på höns kom tanken att omarbeta denna till ett etologiprojekt för biologiämnet på gymnasiet. Projektet innebär att eleverna får arbeta med en observationsstudie från grunden, och goda möjligheter finns att integrera andra ämnen i detta. Människan började domesticera höns för tusentals år sedan, en process där djur utvecklar ett adaptivt beteende till människan och dess miljö. Drygt hundra år tillbaka startade den intensiva aveln på höns som gett upphov till dagens tamhöns (Gallus gallus domesticus). White Leghorn är en av de domesticerade raserna avlad för hög äggproduktion, och härstammar från det röda djungelhönset (Gallus gallus). Studiens syfte var att se hur lång tid det tog för höns att återhämta sig efter en stressupplevelse och om det fanns en skillnad i återhämtningsförmågan mellan raserna. Resultaten tyder på att hönsen återhämtat sig efter 130 minuter, men vissa beteenden visade en signifikant skillnad med avseende på ras, kön och tid. White Leghorn verkade bli mer påverkade av stressmomentet och uppvisade både stressade och avslappnade beteenden. Trots detta verkar de ha en effektivare återhämtning än djungelhönsen som uppvisade procentuellt mer komfortbeteenden, vilket i detta sammanhang kan indikera stress då olika beteendemekanismer kan interagera i djuret och trigga igång ett utforskande beteende vid låga stressnivåer.

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