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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.
1

Aiming for the moon

Andes, Derek 01 May 2012 (has links)
Space Camp sets sail on a Cruise to the Moon.
2

Parallels between playbacks and Pleistocene tar seeps suggest sociality in an extinct sabretooth cat, Smilodon

Carbone, C, Maddox, T, Funston, PJ, Mills, MGL, Grether, GF, Van Valkenburgh, B 23 February 2009 (has links)
Inferences concerning the lives of extinct animals are difficult to obtain from the fossil record. Here we present a novel approach to the study of extinct carnivores, using a comparison between fossil records (nZ3324) found in Late Pleistocene tar seeps at Rancho La Brea in North America and counts (nZ4491) from playback experiments used to estimate carnivore abundance in Africa. Playbacks and tar seep deposits represent competitive, potentially dangerous encounters where multiple predators are lured by dying herbivores. Consequently, in both records predatory mammals and birds far outnumber herbivores. In playbacks, two large social species, lions, Panthera leo, and spotted hyenas, Crocuta crocuta, actively moved towards the sounds of distressed prey and made up 84 per cent of individuals attending. Small social species (jackals) were next most common and solitary species of all sizes were rare. In the La Brea record, two species dominated, the presumably social dire wolf Canis dirus (51%), and the sabretooth cat Smilodon fatalis (33%). As in the playbacks, a smaller social canid, the coyote Canis latrans, was third most common (8%), and known solitary species were rare (!4%). The predominance of Smilodon and other striking similarities between playbacks and the fossil record support the conclusion that Smilodon was social.
3

Experts Recommender System Using Technical and Social Heuristics

2013 July 1900 (has links)
Nowadays, successful cooperation and collaboration among developers is crucial to build successful projects in distributed software system development (DSSD). Assigning wrong developers to a specific task not only affects the performance of a component of this task but also affects other components since these projects are composed of dependent components. Another aspect that should be considered when teams are built is the social relationships between the members; disagreements between these members also affect the project team’s performance. These two aspects might cause a project’s failure or delay. Therefore, they are important to consider when teams are created. In this thesis, we developed an Expert Recommender System Framework (ERSF) that assists developers (Active Developers) to find experts who can help them complete or fix the bugs in the code at hand. The ERSF analyzes the developer technical expertise on similar code fragments to the one they need help on assuming that those who have worked on similar fragments might understand and help the Active Developer; also, it analyzes their social relationships with the Active Developer as well as their social activities within the DSSD. Our work is also concerned with improving the system performance and recommendations by tracking the developer communications through our ERSF in order to keep developer profiles up-to-date. Technical expertise and sociality are measured using a combination of technical and social heuristics. The recommender system was tested using scenarios derived from real software development data, and its recommendations compared favourably to recommendations that humans were asked to make in the same scenarios; also, they were compared to the recommendations of the NaiveBayes and other machine learning algorithms. Our experiment results show that ERSF can recommend experts with good to excellent accuracy.
4

Socialinis darbas vaikų dienos centruose / Sociality work at children day's centre

Burneikienė, Daiva 02 July 2006 (has links)
In the stage of Lithuanian educational reform was finished to create the new types of educational astablishments (gymnasiums, children's day centers, childhood's educational centers, the young schools and others). They let to cater children's educational need from meager social enviroment. Already from 1996 it is finished to create, not governmental organization's initiative, day centers for children in the council territory. The dey centre is doig social and primary and supplementary favors establishment for problematic falily children's and theis parent's. Children day centers net hot up, create new centers, because the favors' need in it is growing. However, today not all children whom need to visit this cenre have possibility to visit them, because the net those center's is not enough expanded. Because the day centers as specific establishment's action organization standards' we yet haven't got is difficult to regard concrete center social-economoc efficacy and advisability.
5

The role of factors promoting genetic diversity within social insect colonies

Sirviö, A. (Anu) 01 June 2010 (has links)
Abstract The evolution of sociality is often associated with close relatedness and genetic similarity of interacting individuals. However, colonies of advanced social insects (e.g. ants, bees and wasps) characterized by large colony size and division of tasks, are also shaped by acquisition of genetic diversity by polyandry, polygyny, recombination and even by hybridization. The balance between forces selecting for high relatedness on one hand and for improved colony performance though increased genetic diversity on the other hand forms an intriguing area of research. My study has produced the first genetic linkage maps for ants (Acromyrmex echinatior and Pogonomyrmex rugosus) and social wasps (Vespula vulgaris). Together with the findings of earlier honeybee research, it is shown that advanced eusocial insects have higher recombination rates than any other insect (or animal) studied so far. The estimates obtained here were 14 cM/Mb for P. rugosus, 9.7 cM/Mb for V. vulgaris and 6.2 cM/Mb for A. echinatior. Pogonomyrmex harvester ants have a genetic caste determination system in which workers arise from mating between two hybridizing lineages whereas sexuals are produced by within-lineage mating. I evaluated the origin of the lineages and the caste determination system by using 751 variable nuclear genetic markers. Fertile hybrids would lead to introgression, particularly in genomic regions characterized by a high recombination rate and lack of strongly selected loci. The hybridizing lineages (lineage pairs J1/J2 and H1/H2) showed many fixed differences. Nineteen of them were in the constructed linkage map, scattered in different linkage groups. The results suggest that there has been no recent introgression. As the hybrids are viable (as workers), caste differentiation can be affected by many loci scattered throughout the ant genome or by a small number of very strongly selected loci. Genetic diversity in colonies of the ant Formica cinerea is affected by varying levels of polygyny. I tested the hypotheses that the prevalence of endosymbiotic bacteria can vary in polygynous colonies but be either very low or very high in monogynous colonies. However, I found no association between the level of polygyny and endosymbiont prevalence. In addition to Wolbachia, I found two other endosymbiotic bacteria Cardinium and Candidatus Serratia symbiotica which have not been earlier reported from ants. Genetic diversity in insect colonies is affected by polyandry and polygyny. My results indicate that high a recombination rate is also an important factor influencing diversity. Genotypically diverse progenies can enhance colony success, e.g. through effects on division of labour or defence against pathogens. Recombination differs from the other factors in its effects on genetic relatedness among colony members.
6

Genetic influences on parental care in Nicrophorus vespilloides

Bird, Chloe J. January 2010 (has links)
The burying beetle (Nicrophorus vespilloides) has unusually highly developed parental care; parents prepare and maintain a food resource (thereby providing indirect parental care), feed through direct provisioning by regurgitation, and protect their larvae. Parental care is highly variable and can be uniparental female care, uniparental male care, or biparental. There are genetic components to the parenting behaviour of the burying beetle, the amount of direct and indirect care given, and the size of the brood are heritable and therefore genetic traits. In this thesis I have focused on two candidate genes that I predicted would influence parental care behaviour. The first is foraging, which has been shown to influence a range of social and reproductive behaviours in other insect species. Using QRTPCR and pharmacological manipulations I have investigated the role of Nvfor in adult and juvenile burying beetles. The second gene is inotocin, the insect orthologue of oxytocin. Oxytocin has been shown to influence social behaviour as well as many behaviours associated with reproduction in vertebrates and invertebrates, however the effects of inotocin have not yet been investigated in insects. I have used pharmacological manipulations to investigate the role of inotocin in parental behaviour in female burying beetles. Collectively my results demonstrate the central role of Nvfor in the control of direct parental care and the association with major behavioural changes in both adult and larval burying beetles. I have also demonstrated the possible involvement of oxytocin in the control of aggression towards conspecific larvae. These insights suggest the controlling mechanism for the behavioural changes seen in burying beetles is complex and involves interactions between many genes. Combined with previous research on these genes, it is clear they are key components in the evolution of sociality. Finally, my research indicates the power of the candidate gene approach, and suggests additional components of the related pathways that could be investigated.
7

Phylogenetics And Molecular Evolution Of Highly Eusocial Wasps

Lopez-Osorio, Federico 01 January 2016 (has links)
Societies where workers sacrifice their own reproduction and cooperatively nurture the offspring of a reproductive queen caste have originated repeatedly across the Tree of Life. The attainment of such reproductive division of labor enabled the evolution of remarkable diversity in development, behavior, and social organization in the Hymenoptera (ants, bees, and wasps). Wasps of the family Vespidae exhibit a gamut of social levels, ranging from solitary to highly social behavior. The highly social yellowjackets and hornets (Vespinae) have well developed differences in form and function between queens and workers, large colony sizes, and intricate nest architecture. Moreover, certain socially parasitic species in the Vespinae have secondarily lost the worker caste and rely entirely on the workers of a host species to ensure the survival of parasitic offspring. Understanding the evolution of behavioral traits in the Vespinae over long periods of time would be greatly enhanced by a robust hypothesis of historical relationships. In this study, I analyze targeted genes and transcriptomes to address three goals. First, infer phylogenetic relationships within yellowjackets (Vespula and Dolichovespula) and hornets (Vespa and Provespa). Second, test the hypothesis that social parasites are more closely related to their hosts than to any other species (Emery's rule). Third, test the protein evolution hypothesis, which states that accelerated evolution of protein coding genes and positive selection operated in the transition to highly eusocial behavior. The findings of this study challenge the predominant understanding of evolutionary relationships in the Vespinae. I show that yellowjacket genera are not sister lineages, instead recovering Dolichovespula as more closely related to the hornets, and placing Vespula as sister to all other vespine genera. This implies that traits such as large colony size and high paternity are mostly restricted to a particular evolutionary trajectory (Vespula) from an early split in the Vespinae. I demonstrate that obligate and facultative social parasites do not share immediate common ancestry with their hosts, indicating that socially parasitic behavior likely evolved independently of host species. Moreover, obligate social parasites share a unique evolutionary history, suggesting that their parasitic behavior might have a genetic component. Lastly, I analyze transcriptomic data to infer a phylogeny of vespid wasps and use this phylogeny to discover lineage-specific signatures of positive selection. I identify more than two hundred genes showing signatures of positive selection on the branch leading to the highly eusocial yellowjackets and hornets. These positively selected genes involve functions related mainly to carbohydrate metabolism and mitochondrial activity, in agreement with insights from studies of bees and ants. Parallels of functional categories for genes under positive selection suggests that at the molecular level the evolution of highly eusocial behavior across the Hymenoptera might have followed similar and narrow paths.
8

Socialita a ekologie zemních veverek tribu Marmotini. / Sociality and ecology in ground squirrels (tribe Marmotini).

Matějů, Jan January 2012 (has links)
of the Ph.D. thesis Autor: Jan Matějů Name: Sociality and ecology in ground squirrels (tribe Marmotini) Ground-dwelling squirrels are parafyletic group of rodents from the family Sciuridae (tribes Marmotini and Xerini). Ground-dwelling squirrels are semi-fossorial inhabitants of treeless biotopes. They share most aspects of general biology. They usually breed once a year, have exclusively diurnal activity and are omnivorous. On the contrary, ground-dwelling squirrels display different levels of sociality, which makes them an ideal model to study different ecological aspects connected with evolution of sociality. The first part of the Ph.D. thesis is focused on the relationship between sociality and sexual size dimorphism and relative and absolute size of brain. At first, supposing that different levels of sociality are connected with differences in intensity of sexual selection acting on males, we tested association between sociality and sexual size dimorphism as well as association between sexual size dimorphism and body size - so called Rensch rule. Next, we tested correlation between sociality and relative brain size. In agreement with the Social brain hypothesis, we assumed that e.g. solitarily living species should have smaller relative brain size than species living in stable pairs. We found...
9

The User Motivation of Avatar System

Hu, Shun-yi 03 May 2007 (has links)
The purpose of this thesis is to discuss the mental motivation of using Avatar system. There have already existed lots of researches for the motivation of using the related network system in the past. Based upon the findings of the past researches, this thesis sorted out four main motivations: self-fulfillment, escapism, sociality and entertainment, and discussed the correlation between these four motivations and mentality and behaviour intention. This research is conducted by Questionnaire Survey and found out that the motivations of self-fulfillment and entertainment are combined as a new motivation, and the motivations of escapism and sociality are not significantly correlated with the user¡¦s mentality. From this research, therefore, it is concluded that as long as the development of network, the habit and motivation of using network are evolving as well. Future studies could be discussed more to address this difference of evolving, in order to allow that the network operators have a more accurate grasp of the users¡¦ mentality and provide more effective services.
10

Anonymous exchange relations : assisted conception between ova donors and recipients in the United Kingdom

Konrad, Monica January 1996 (has links)
No description available.

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