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Presented is a study on the chemotaxis reaction process and its relation with flow topology. The effect of coherent structures in turbulent flows is characterized by studying nutrient uptake and the advantage that is received from motile bacteria over other non-motile bacteria. Variability is found to be dependent on the initial location of scalar impurity and can be tied to Lagrangian coherent structures through recent advances in the identification of finite-time transport barriers. Advantage is relatively small for initial nutrient found within high stretching regions of the flow, and nutrient within elliptic structures provide the greatest advantage for motile species. How the flow field and the relevant flow topology lead to such a relation is analyzed.
ContributorsJones, Kimberly (Author) / Tang, Wenbo (Thesis advisor) / Kang, Yun (Committee member) / Jones, Donald (Committee member) / Arizona State University (Publisher)
Created2015
Description
Insects have intricate systems they depend on for survival. They live in societies where every individual plays an important role. Ants are a great example of this observation. They are known for having structurally sound societies that ensure the livelihood of the colony. The ant species analyzed for this research, Harpegnathos saltator, portrays a structured colony and serves as a useful example of levels of hierarchy. In the colony of H. saltator, one can find a queen, gamergates, workers, and male ants living underground in Southern India. Recording and analyzing egg-laying rates are important in this study because of the amount of information it provides. It is used especially when observing the relationship among the gamergates in colonies with varying colony sizes. Three different methods were used to record the egg-laying rates, each providing insight into valuable information. Results show that the smaller colonies with fewer identified gamergates do share an equal amount of egg-laying. In larger colonies, it appears that there are more active identified gamergates than others. Egg-laying duration times are smaller in colonies with fewer gamergates. It is also found that the presence of brood does not affect egg-laying rates and reproductive inhibition could be a possibility based on two of the colonies observed F65 and F21. Based on the data found, a more active colony that attempts to maintain stability by demonstrating aggression may be affecting the reproduction of gamergates. Future work that would further strengthen the research and conclusions made would involve further observation of colonies, both large and small, with varying numbers of gamergates. More observation involving behavior among gamergates and workers would also be beneficial. Mathematical modeling could also be incorporated to create equations that could determine information about colonies based on size, number of gamergates, and egg-laying rates.
ContributorsMayoral, Alejandra (Author) / Kang, Yun (Thesis director) / Liebig, Juergen (Committee member) / College of Integrative Sciences and Arts (Contributor) / Barrett, The Honors College (Contributor)
Created2017-12
Description
For colonies of ponerine ant species, sterility regulation after a founding queen's death is not totally achieved in the worker caste, and the possibility of sexual reproduction is opened to workers. The persisting survival of these colonies is dependent on capturing the optimal reproductive ratio; yet, an informational gap bounds the mechanisms detailing the selection of new reproductives and the suppression of ovarian development in rejected reproductives. We investigated the mechanisms of worker policing, one of the primary methods of ovarian suppression, through continuous video observation for a period of five days at the start of colony instability. Observations suggest policing in H. saltator is performed by a majority of a colony, including potential reproductives, and requires multiple events to fully discourage ovarian growth.
ContributorsChien, Jeffrey (Co-author) / Barat Ali, Fatima (Co-author) / Kang, Yun (Thesis director) / Liebig, Juergen (Committee member) / School of Mathematical and Statistical Sciences (Contributor) / Mechanical and Aerospace Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2018-12