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Undergraduate Research Opportunities Program

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Now showing 1 - 10 of 37

Medical Marijuana: Redefining the Social Politics of Reality

(Georgia Institute of Technology, 2008-12-15) Farmer, Kathryn Elizabeth

Medical marijuana is a pertinent and controversial topic in contemporary American society. Those against medical marijuana cite the "dangers" the drug presents to society and claim that there is no, and has never been, any medical utility of marijuana. Advocates of medical marijuana refute preconceived ideas of marijuana being dangerous and cite thousands of years of historical evidence that lends credence to the proposed therapeutic effects. Since the prohibition of marijuana in 1937, the federal government has portrayed a negative image of marijuana that remained dominant in public opinion until it began to be challenged forty years ago. Contrary to the statements of the federal government that marijuana has no medical use, world history and modern science has indicated its therapeutic potential. As a result of several medical marijuana laws being enacted since 1996, Congress held a hearing in 2001 to discuss the issues of medical marijuana, federal law enforcement, and the supremacy clause. Many images of marijuana and the user were presented that represented old, traditional beliefs, as well as new images that represent the emerging medical marijuana culture. The disparate views of marijuana can be explained by each person’s own special perception of the drug, which is shaped by one’s own pre-conceived notions, environment, personal experiences, and special view of "reality." Marijuana Medical marijuana
Lateral gene transfer of pandemic Vibrio parahaemolyticus genomic island genes

(Georgia Institute of Technology, 2008-12-15) Silberger, Daniel James

Vibrio parahaemolyticus is an emerging enteric pathogen. The O3:K6 serotype has become pandemic, and the genome has been sequenced for the RIMD2210633 strain of this serotype (20). The thermostabile direct hemolysin (tdh), thermostabile related hemolysin (trh), and two distinct Type III Secretion Systems (T3SS) have been implicated in virulence. Deletion studies have determined that the T3SS alone are sufficient to induce eukaryotic cell apoptosis. The T3SS loci are found within two separate genomic islands. Because genomic islands are known to be disseminated by Lateral Gene Transfer (LGT), we examined the distribution of the pandemic genomic island genes among clinical and environmental V. parahaemolyticus isolates and also among closely-related environmental Vibrio spp. using primers designed to amplify hemolysins and T3SS effectors previously characterized for V. parahaemolyticus strain RIMD2210633 (23). We also examined the distribution of a hypothetical bacteriocin, encoded by vpa1263, within another genomic island that is similar to the bacteriocins produced by Escherichia coli. Preliminary screens for the bacteriocin gene suggest that many clinical strains and some environmental strains contain vpa1263. PCR screens for the T3SS effector genes have shown that 22% of closely-related environmental Vibrio spp. contain at least one T3SS1 or one T3SS2 effector gene. Sequencing of housekeeping genes is ongoing to confirm these findings.
Characterizing Single Ventricle Patient-Specific Anatomy Using Segmentation of MRI and 3D Reconstruction to Aid Surgical Planning

(Georgia Institute of Technology, 2008-08-01) Jayaprakash, Gopinath

Single ventricle congenital heart defects occur 2 per every 1000 live births in the USA. In these cases, cyanosis occurs due to the mixing of venous deoxygenated blood and oxygenated blood from the lungs. These defects are surgically treated by the total cavo-pulmonary connection (TCPC), where the superior and inferior vena cavae are connected to the pulmonary arteries routing the systemic venous return directly to the lungs. However, this Fontan repair results in high energy losses and therefore the optimization of this connection prior to the surgery could significantly improve post-operative performance. In this paper, the in-house segmentation and 3D reconstruction scheme is used in the following studies. First, 3D geometrical analysis of the TCPCs is used to determine the advantages and disadvantages of two commonly performed TCPC palliations intra-atrial and extra-cardiac configurations. Then, a surgical planning outline is proposed with segmentation of pre and post surgical Magnetic Resonance Imaging (MRI) data followed by the 3D reconstruction with emphasis on extracting surrounding vessels and structures. A pediatric surgeon performs a virtual surgery on the reconstruction of the patient s pre-Fontan anatomy prior to the actual surgery. A segmentation of the heart, aorta and surrounding vessels superimposed with the Glenn, when used with the SURGEM® tool, simulates the actual Fontan operation. This outline allows the surgeon to envision numerous scenarios of possible surgical options, and accordingly to predict the post operative procedures. The segmentation tool is improved upon to increase the accuracy and efficiency of the process and enhance the quality of the anatomical reconstructions.
Cylindrical beam volume holograms recorded in reflection geometry for diffuse source spectroscopy

(Georgia Institute of Technology, 2008-05-06) Jolly, Sundeep

Multimodal multiplex spectroscopy (MMS) has been demonstrated to increase the optical throughput of a spectrometer as opposed to that of conventional optical spectrometers and has been implemented using three-dimensional photonic crystals and spherical-beam volume holograms recorded in the transmission geometry as spectral diversity filters. While such efforts have resulted in compact and sensitive Fourier-transform holographic spectrometers, there still remains much room for performance improvements. Previous studies [6,7,9] have proven the utility of spherical-beam volume holograms recorded in the transmission geometry as spectral diversity filters for spectrometers. The role of the recording geometry in the performance of cylindrical-beam volume holograms as spectral diversity filters is investigated here. The transmission recording geometry is compared to the reflection recording geometry on the basis of the spectral operating range of the resultant spectral diversity filters.
Density-dependent Stiffness in Petiole Biomechanics

(Georgia Institute of Technology, 2008-05-05) Wilson, Christina

Morphological features of plants vary with increasing size. This relationship between different physical characteristics and size is referred to as allometry. Recently allometric research focused on plants and in particular plant leaves due to their importance in nutrient flow and gas exchange. Allometric plant research aims to enhance our understanding of the ontogeny of plants and offers a tool for ecological modeling. Previous allometric models have glanced over the influence of biomechanics on leaf form and function. This research will test if density-dependent stiffness of petioles is variable or if it scales with leaf mass. In order to test the variance of stiffness in leaf petioles, Young s modulus (E) was measured by modeling the petioles as simply loaded beams. Young s modulus was shown to vary among different species, even those of the same genus. Density-dependent stiffness varied with leaf size for some herbaceous species but not for other woody tree species. Future research should investigate the biomechanical role of a possible redistribution of structural tissue and how this rearrangement would affects petiole stiffness and overall petiole function.
Repeated Testing of Working Memory Capacity

(Georgia Institute of Technology, 2008-05-05) Carter, Laura

Working memory capacity is measured by a variety of memory span tasks and can account for about 40% of inter-individual variation in fluid intelligence (Broadway &Engle, in preparation). In the present study, ten participants performed a widely accepted valid test of WMC, the Running Memory Span task (Pollack, Johnson, &Knaff, 1959), twenty-five times over five sessions to assess test-retest reliability and the extent of practice effects. Results confirmed expectations that memory performance would improve but that the rank ordering of individuals on performance would remain consistent over repeated testing.
Visual and Auditory Velocity Perception and Multimodal Illusions

(Georgia Institute of Technology, 2008-05-05) Gasaway, Katherine S.

Although ambiguous and conflicting sensory information from different sensory modalities is common, people seldom experience perceptual ambiguities or conflict between senses. Just as the retinal nerve blind spot is filled in and seldom seen, conflicting or otherwise confusing sensory information is resolved in favor of the most appropriate modality, eliminating the confusion from conscious experience. The ventriloquism effect and auditory driving are two examples of perceptual phenomena arising from this sensory override. This research explores the hypothesis that velocity perception is subject to the same effects. Subjects were presented with two bimodal (auditory-visual) stimulus pairs and asked to determine which of the visual stimuli was moving faster. In a V2A2/V2A1 condition, participants responded significantly more frequently that the first visual stimulus was faster than in any non-target condition. This effect was not found for V2A2/V2A3 trials.
Performance Information Sharing Middleware

(Georgia Institute of Technology, 2008-05-05) Reiss, Charles

This thesis presents a design for distributed monitoring system designed to enable monitoring-informed optimizationsin distributed applications. Microbenchmarks and an evaluation in a scientific-computing scenario are presented. The monitoring system is intended to assist when application requirements cannot be easily expressed in a form suitable for existing autonomic computing approaches. The design embeds awareness of the application's topology into the monitoring system so queries can reference a node's place in the application without embedding extra assumptions about the overall layout of the application. Through integration with dynamic code generation, users may make potentially application-specific metadata available and use such data within dynamically deployed filters and transformation functions. Evaluations demonstrate that this approach can provide timely and useful information with low overhead.
Rotifer Ecotoxicology: Behavioral Avoidance of Toxicants

(Georgia Institute of Technology, 2008-05-05) Weigel, Emily G.

Previous rotifer ecotoxicology studies have shown varied effects of sublethal concentrations of hormones and metals on species but have largely ignored toxicant effects on behavior. Given the importance of chemical cues for mating, grazing, and predator avoidance, the phenomenon of behavioral response to pollutants is a critical topic impacting rotifer survival and reproduction. Dual- and tri-chamber test slides similar to Y-tubes were developed to test rotifer behavioral responses to sublethal concentrations of several toxicants. Rotifers were placed in a start chamber between a control chamber and test chamber containing a toxicant, and after fifteen minutes, rotifer distribution in all chambers was recorded. No significant distributional effects were observed for cadmium (2μg/L), pentochlorophenol (2μg/L), flutamide (8μg/L) nor progesterone (8μg/L). Significant deviation from a random distribution was recorded for selenium (2μg/L), lead (8μg/L), and rotifer conditioned medium. In addition, significant avoidance was found for copper (2μg/L) and mercury (0.2μg/L), even in tests with the start chamber containing the toxicant. These data suggest that rotifers can detect and avoid certain toxicants at sublethal levels. Avoidance often occurs at levels below published lethal concentrations (LC50s) on which many water quality criteria are based. Avoidance can alter rotifer survival and reproduction, leading to reductions in rotifer abundance and energy transfer to higher trophic levels.
Separation and Identification of Peptides by Supercritical Fluid Chromatography Coupled with Mass Spectrometry

(Georgia Institute of Technology, 2008-05-05) Terrett, Stuart

The presence of certain proteins in physiological fluids could be used as an early diagnostic tool for disease; however, because of the large concentration range of proteins and the number of distinct chemical species the detection and quantification of these proteins is problematic. This research focuses on the ability to separate proteins using supercritical fluid chromatography (SFC), a form of chromatography that uses supercritical carbon dioxide (scCO2) as the mobile phase. This project was divided into two parts. The first is the synthetic aspect that involves reacting an amino acid, in this case tyrosine, with dimethyl-tert-butyl-chlorosilane which substitutes onto the hydroxyl group to increase its solubility in scCO2. The synthesis, purification, and characterization of this novel molecule have been successfully completed. The second part of the project is the optimization of the chromatograph itself, necessitating a complete rebuild of an extant SFC. Much of the internal controls were bypassed or replaced; at this stage, the SFC is capable of injecting and detecting large organic compounds and amino acids. Research efforts are now focused on separating the silylated tyrosine from nonderivatized amino acids. Once achieved, the synthesis will be scaled up to include other amino acids and ultimately small peptides, which should separate more readily and provide identification of target proteins.