The domestic chick (Gallus gallus domesticus) has been widely used as an animal model to investigate spatial orientation and the neural mechanisms underlying this function. In all vertebrate species the hippocampus plays an essential role in spatial orientation. Since the hippocampus is a bilateral structure, it is important to investigate the specific role of the left and the right hippocampi in spatial processing. Although, the domestic chick has been often used as animal model to assess cognitive lateralization, the involvement of the left and the right hippocampal formation in spatial orientation has been poorly investigated in this model. Behavioral studies using monocular eye occlusion have shown that in chicks the left eye-system (right hemisphere) is involved in the elaboration of spatial relational information, while the right eye-system (left hemisphere) processes local information. However, while visual lateralization in chicks had been traditionally considered to be induced by embryonic light exposure, recent studies suggest the presence of structural and behavioural asymmetries also in dark-incubated chicks. Thus, the main aim of this thesis was to test the lateralization of hippocampal functions in dark incubated chicks, both in spatial and non-spatial tasks. In the first study dark-incubated chicks were trained to orient in a large circular arena using spatial relational information provided by free-standing objects. Once chicks reached a learning criterion they were tested binocularly or under a monocular eye-occlusion condition. This study provided the first demonstration that domestic chicks are able to orient by relational spatial information provided by free-standing objects, in binocular vision conditions. However, if either one of the two eyes was occluded, chicks failed the orientation task. These results show that at least in dark-incubated chicks binocular integration is needed to solve this spatial orientation task. We also investigated if chicks have a preference to orient by local or spatial information provided by free-standing objects and if this ability is influenced by eye occlusion. Chicks preferred to use local over spatial cues to orient, both in binocular and monocular conditions (independently of which eye was occluded). These results indicate that local cues are processed by both eye-systems and do not require access to information from both eyes, contrary to relational spatial cues. Using the same setup, in the second study we directly investigated the involvement of chicks’ left and right hippocampal formation during orientation by free-standing objects. For this purpose we performed an immunohistochemical staining of the immediate early gene product c-Fos (a neural activity marker). Two independent groups of dark-incubated chicks were trained to find food in the large circular arena and the level of hippocampal activation was compared between the two groups. One group was trained to orient exclusively by local cues, while the other was orienting by spatial relational information provided by free-standing objects. This revealed selective activation of the right hippocampus during orientation by spatial relational information in dark-incubated chicks. While monocular occlusion has often been used to test lateralization of spatial functions in chicks, it is still unclear whether this manipulation affects hippocampal activation. The aim of the third study was to clarify this issue, by exposing dark-incubated chicks to a novel environment in conditions of monocular occlusion or binocular vision. Activation of the hippocampal formation was once again measured by c-Fos expression. Exposure to a novel environment is known to trigger hippocampal activation in different animals, including domestic chicks. As expected, exposure to the novel environment activated the hippocampus in binocular vision conditions. However, if either one of the eyes was occluded, the hippocampal c-Fos expression did not rise above what observed in the baseline condition (chicks maintained in a familiar environment). Thus, successful hippocampal response to a novel environment requires input from both eyes. Our results also suggest that monocular occlusion equally affects the left and the right hippocampus. Overall, access to information from both eyes plays a crucial role for the acquisition of a spatial map of a novel environment, in line with the behavioral results of the first study. Moreover, a task independent lateralization effect, with higher c-Fos expression in the left compared to the right hippocampus, could be observed in all the experimental conditions. This confirms the presence of neuroanatomical lateralization in dark-incubated chicks. The last study investigated whether chicks’ hippocampus would also respond to novel social stimuli, in line with the activation observed in this structure after exposure to a novel environment. Only few studies have directly investigated the involvement of birds’ hippocampal formation in social functions. Here, the hippocampal activation was compared between chicks exposed to an unfamiliar conspecific vs. chicks exposed to a familiar one. We found that the ventral and dorsomedial portion of the right hippocampus of dark-incubated chicks responds to an unfamiliar individual. This provides the first demonstration of hippocampal sensitivity to social novelty in birds. Overall the studies performed in this thesis indicate a selective lateralized involvement of domestic chicks’ hippocampal formation not only in spatial, but also in social functions.

The coastal plain of the southeastern United States is historically wet pine savannahs, prairie, and hardwoods. However, many exotic species have invaded this area and become a serious threat to native forest ecosystems. Among those exotic species, Chinese tallow (Triadica sebifera) has become one of the most pervasive tree species in the southern coastal states, including Alabama, Mississippi, Louisiana, and Texas. Therefore, to understand the distribution and spread mechanisms has become important in the management and control of Chinese tallow in the southeastern United States. In this research, distribution and spread mechanisms of Chinese tallow were studied at multiple spatial scales, including regional, landscape, and stand. Effects of predisposing (community and landscape features) and inciting (natural disturbance and human activities) factors on Chinese tallow invasion had been evaluated by using a comprehensive data set (field data and Forest Inventory and Analysis data) and spatial statistical models. Results indicated that propagule pressure of Chinese tallow is the main force driving tallow dispersal at different spatial scales. Predisposing and inciting factors such as natural disturbances, anthropogenic disturbances, forest types, forestland ownerships, and landscape features are significantly related to the spread of Chinese tallow at different spatial scales. Regionally, Chinese tallow initially started to spread from southern Texas and Louisiana to the northeastern portion of the Gulf Coastal area. At landscape and stand scales, Chinese tallow has commonly invaded from edges of forests and habitats such as roads and firebreaks. Inciting factors, including hurricanes/storms and prescribed fires, could accelerate the spread of Chinese tallow at different spatial scales, especially in habitats that have previously been invaded. Compared to pine forests, it is easier for Chinese tallow to invade bottomland hardwood forests at the regional scale. The efficient dispersal distance of tallow seeds is 250-300 m, and its distribution is affected by the microtopography in forest stands. Management of Chinese tallow invasion should be focused at selected scales, such as landscape and stand levels, because of variations of site conditions.

Aflatoxin is a carcinogen produced by the fungus Aspergillus flavus that causes millions of dollars in agriculture losses in the southeastern US. This thesis examines the dispersal of A. flavus on two corn inbred lines, resistant (Mp313E) and susceptible (B73), which differ in total aflatoxin accumulation after infection with A. flavus. After inoculating corn kernels with the fungus an RNA analysis was used to determine the location (number of kernels away from inoculation site) and abundance of A. flavus at weekly intervals. A. flavus started its spread at 7 days after inoculation (DAI) on both corn lines. The B73 corn line showed a constant spread of 3.4mm per day until the entire ear was infected at 21 DAI. The spread on Mp313E did not proceed beyond 3 kernels away from the inoculation site following 7 DAI. The results are significant because they show a faster rate of spread than previously reported and they help quantify the ability of Mp313E to mitigate infection.

No description available.

No description available.

Spatio-temporal data analysis involves modeling a variable observed at different locations over time. A key component of space-time modeling is determining the spatial scale of the data. This dissertation addresses the following three questions: 1) How does spatial aggregation impact the properties of the variable and its model? 2) What spatial scale of the data produces more accurate forecasts of the aggregate variable? 3) What properties lead to the smallest information loss due to spatial aggregation? Answers to these questions involve a thorough examination of two common space-time models: the STARMA and GSTARMA models. These results are helpful to researchers seeking to understand the impact of spatial aggregation on temporal and spatial correlation as well as to modelers interested in determining a spatial scale for the data. Two data examples are included to illustrate the findings, and they concern states' annual labor force totals and monthly burglary counts for police districts in the city of Philadelphia. / Statistics

Yes / Early diagnosis of Alzheimer’s disease (AD) is essential if treatments are to be administered at an earlier point in time before neurons degenerate to a stage beyond repair. In order for early detection to occur tools used to detect the disorder must be sensitive to the earliest of cognitive impairments. Virtual reality (VR) technology offers opportunities to provide products which attempt to mimic daily life situations, as much as is possible, within the computational environment. This may be useful for the detection of cognitive difficulties. We develop a virtual simulation designed to assess visuospatial memory in order to investigate cognitive function in a group of healthy elderly participants and those with a mild cognitive impairment. Participants were required to guide themselves along a virtual path to reach a virtual destination which they were required to remember. The preliminary results indicate that this virtual simulation has the potential to be used for detection of early AD since significant correlations of scores on the virtual environment with existing neuropsychological tests were found. Furthermore, the test discriminated between healthy elderly participants and those with a mild cognitive impairment (MCI).

In this dissertation, a variable selection method for spatial data is developed. It is assumed that the spatial process is non-stationary as a whole but is piece-wise stationary. The pieces where the spatial process is stationary are called regions. The variable selection approach accounts for two sources of correlation: (1) the spatial correlation of the data within the regions, and (2) the correlation of adjacent regions. The variable selection is carried out by including indicator variables that characterize the significance of the regression coefficients. The Ising distribution as prior for the vector of indicator variables, models the dependence of adjacent regions. We present a case study on brook trout data where the response of interest is the presence/absence of the fish at sites in the eastern United States. We find that the method outperforms the case of the probit regression where the spatial field is assumed stationary and isotropic. Additionally, the method outperformed the case where multiple regions are assumed independent of their neighbors. / Ph. D.

ITC/USA 2005 Conference Proceedings / The Forty-First Annual International Telemetering Conference and Technical Exhibition / October 24-27, 2005 / Riviera Hotel & Convention Center, Las Vegas, Nevada / With the development of Internet and the urgent need for GIS (Geographic Information System), XML (eXtensible Markup Language) provides a powerful new way for new web application. This paper makes a research on the application of SVG based on XML in the WebGIS (World Wide Web Geographical Information System). In this paper, the characteristics of XML are illuminated in short; the application of XML in WebGIS is discussed and the features of SVG and its usage with XML are presented; a design of SVG based on XML in the WebGIS system is given.

published_or_final_version / Industrial and Manufacturing Systems Engineering / Doctoral / Doctor of Philosophy