When a society experiences a collapse, political authority becomes decentralized, large settlements often become abandoned, economic specialization decreases; and monumental building projects, artistic, and literary achievements slow drastically. The Rio Verde Valley, a coastal floodplain located in the region of Oaxaca in Southwest Mexico, experienced such a collapse at the end of the Terminal Formative period (150 BC to 250 AD). A period of decentralization followed, with regional centers becoming the main seats of authority throughout the region. My aim is to understand how this collapse affected residential population mobility in the lower Rio Verde Valley between the pre-collapse Terminal Formative and post-collapse Early Classic periods. I seek to answer the question: could this political collapse have caused intra-regional migration amongst the people of Ancient Oaxaca? To answer this, I analyzed the stable 18O and 13O isotopes in a set of 21 samples of human long bone excavated from the Terminal Formative archaeological site of Yugüe and the Early Classic site of Charco Redondo. Oxygen isotope analysis is based on the principle that bone apatite and tooth enamel hold traces of oxygen isotopes found in the water that people drink, and that varying values of those isotopes reflect that the water was obtained from different sources. Based on literature surrounding the process of political collapse in ancient Mesoamerica and beyond, I expected to find evidence that intra-regional population mobility increased after the Terminal Formative period collapse. Instead, I found evidence of little to no mobility in both the Terminal Formative period site and the Early Classic period site, showing that the political collapse likely did not affect intra-regional mobility. These findings provide valuable insight into how human migration patterns correspond with political changes, both in the archaeological record of past civilizations and in modern societies.

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Abdominal pumping is a well-known behavior in insects, thought to function largely in respiratory processes. In particular, the abdominal pump is considered to produce ventilation of air in the tracheal system, but the mechanistic link between abdominal movement and flow of air is not well understood. In this thesis, we explore the relationship between the abdominal pump and ventilation of air using pupal and adult forms of the darkling beetle Zophobas morio. First, we investigated the mechanical linkage between abdominal pumping and active ventilation in pupae by simultaneously measuring abdominal movement, hemolymph pressure, CO2 emission, and deformation of tracheal tubes. This study revealed that pupae with low metabolic rates do indeed exhibit tracheal compression, which is coincident with abdominal pumping and pressure pulsation. However, more than 63% of the abdominal pumps and associated pressure pulsations did not lead to tracheal compression. This result can be explained by the status of the spiracles; when the system is closed, little compression in the tracheae can occur. Therefore, we conclude that abdominal pumping in insects does not necessarily lead to ventilation and may serve other functions, such as producing hemolymph flow for circulation. Insects have an open circulatory system, with flow driven largely by the small dorsal vessel. Within the open coelom, hemolymph pressure should be mostly uniform, suggesting that abdominal pumping does not produce hemolymph flows within the main body cavity. We tested this assumption by simultaneously measuring hemolymph pressure in different locations in the coelom. Within the abdomen and thorax, hemolymph pressure is nearly uniform, as expected. However, hemolymph pressures are significantly different between the abdomen and thorax. This suggests that the coelom is compartmentalized, and that abdominal pumping can induce hemolymph flow within the coelom. Throughout these experiments, we faced a common difficulty inherent to flow-through respirometry systems: they are incapable of providing direct, instantaneous measurement of gas concentration. Previous methods are not able to reconstitute the rapid dynamical changes in respiratory signals that are required for precise temporal analysis. Therefore, we developed two new methods to accurately recover instantaneous gas exchange signals, based on new models of the impulse response of the system. These methods enabled us to accurately recover fast- changing respiratory signals with a higher fidelity than previously possible. Using these methods, we demonstrate the synchronization of respiratory data with other physiologically relevant signals, such as pressure and abdominal movement. This research was supported by NSF grant #0938047 and the Virginia Tech Institute for Critical Technology and Applied Science (ICTAS). / Ph. D.

Yes / Voltage instability problems in power system are an important issue that should be taken into consideration during the planning and operation stages of modern power system networks. The system operators always need to know how far the power systems from voltage collapse in order to apply suitable action to avoid unexpected results. This paper propose a review of some static voltage stability indices found in the literature to study voltage collapse reveals that various analytical tools based on different concept to predict voltage collapse phenomena. These static voltage stability indices present reliable information about the closeness of the power system to voltage collapse and identification of the weakest bus, line and area in the power network. A number of static voltage stability indices have been proposed in the literature, but in this only four of them will be considered. The effectiveness of these indices is demonstrated through studies in IEEE 14 bus reliability test system. The results are discussed and key conclusion presented. / MSCRC

This thesis is an investigation of embracing the figural possibilities of palimpsest through layering new construction upon extant. The existing building, a neglected warehouse in Louisville, Kentucky, is challenged by a new program that is intended to subdivide the vast, horizontal space and reconstrue the two distinctly ordered systems to formulate new interdependent spatial relationships. Filtered critical moments and continuities are explored through the implication of collapse, the embrace of datum and ideatum, and the lateral play of scale and repetition. Through development of these new relationships, the building is intended to not be a product but a construct of process, allowing particular moments of composition to exist within a collage of space and time. / Master of Architecture