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Undergraduate Research Opportunities Program

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Now showing 1 - 10 of 73

Effects of Word Replacement on Juror Perceptions and Guilt Ratings During a Criminal Trial

(Georgia Institute of Technology, 2009-12) Coons, Courtney A.

This research was performed with the aim of improving the body of knowledge on juror perceptions during criminal trials. Three juries were formed of men and women at least 18 years old. The juries witnessed key excerpts of a criminal trial, either edited or unedited for content and then placed in a room for deliberation. Deliberations were videotaped and the juries had up to 45 minutes to return a verdict. Two juries viewed the content-edited trials, removing all instances of the word "rape". One of these juries was told of the editing, the other was not. After all juries had returned a verdict, each individual juror was asked to take an exit survey inquiring about their particular perceptions of the trial, and their personal conviction of guilt or lack thereof. All juries returned a verdict of 'not guilty' , however the exit surveys showed that more than 50% of the jurors that viewed the un-edited trial had an abiding conviction of guilt but rendered a not guilty verdict based on a lack of physical evidence. The content-edited conditions, however, had only 3 people between them that believed the defendant to be guilty of the crime of rape.
Zinc Oxide coated Carbon Nanotubes as Piezoelectric Nanogenerators

(Georgia Institute of Technology, 2009-12) Mason, Celeste

Piezoelectric nanogenerators were created using two designs: coating carbon nanotubes (CNTs) grown on a silicon wafer substrate with a thin film of zinc oxide (ZnO), coupled with an additional gold-coated CNT grown wafer to act as an electrodes and coating carbon nanotubes (CNTs) grown on carbon fiber with each type of coating to form flexible electrodes. The CNTs on all samples were grown using a standard recipe, with thermally evaporated iron as catalyst. ZnO deposition techniques such as RF sputtering and ion-assisted deposition were used. Gold deposition was accomplished by thermal evaporation and RF sputtering. Once electrodes were combined, preliminary electrical testing resulted in measurement of current densities of up to 4.2x10-7 A/cm3. Additional electrical measurements indicated that the current generated was the result of piezoelectric behavior of the ZnO coating. These values may be increased with better penetration of both gold and ZnO coatings during deposition on the CNTs. Improvement of film quality, such as gold adhesion and ZnO crystal orientation, may also increase current generation.
Amino Acid Profiling by Reactive Desorption Electrospray Ionization Tandem Mass Spectrometry (DESI-MS/MS)

(Georgia Institute of Technology, 2009-12) Rizzo, David G.

Desorption electrospray ionization mass spectrometry (DESI MS) has gained significant recognition over the past few years because of its simplicity and rapid throughput capabilities, allowing for the direct analysis of samples with a wide variety of sizes, shapes, and chemistries. Addition of various reagents into the DESI spray solvent enables atmospheric pressure ion molecule reactions between these reagents in the charged micro droplets and analyte molecules on the sample surface affording improved selectivity and sensitivity in some cases. Presented is a rapid screening method for amino acids (aas) based on reactive DESI. Amino acids have been shown to play key roles in the regulation of cellular processes. They are also particularly vital in the determination of metabolic disorders such as phenylketonurea, homocystinuria, and tyrosinemia. The most specific and reliable methods for diagnosing these disorders are based on the determination of aas in body fluids using methodologies such as gas/liquid chromatography, tandem MS, and various combinations thereof. However, these methods are usually time-consuming, increasing the time physicians wait before administering treatment or regulating the diet of diseased infants. The reactive DESI approach presented here is based on the formation of stable noncovalent complexes between alpha-cyclodextrin (dissolved in the spray solvent) and amino acids present in the sample affording a selective method for their detection. However, the selectivity and sensitivity of screening for aas was improved by performing the MS analysis in the multiple reaction monitoring mode when using a quadrupole ion trap or by the precursor ion scan when using a triple quadrupole MS instrument, affording an average twenty-five times sensitivity improvement compared to analysis in full scan mode. The observation of similar complexes with various carboxylic acids including formic acid and acetic acid, and evidence from tandem MS experiments indicate that amino acid:alpha-cyclodextrin complexation reactions occur by hydrogen bonding interaction with carboxyl group of the aas. The specificity and sensitivity provided by this approach seems very promising for applications in the rapid screening of aas directly from body fluids including urine and plasma for amino acid disorders in a clinical setting.
Training Novices on Hierarchical Task Analysis

(Georgia Institute of Technology, 2009-12) Felipe, Sarah

The training of a complex task such as task analysis is an area that very few have explored. This study examines how different training methods affect knowledge acquisition, focusing on content learned and errors made by novices in the initial phase of learning of Hierarchical Task Analysis (HTA). Three types of declarative instructions were compared: procedures, decision/actions, and concept map, which were representative of different types of diagrams (matrix, network, hierarchy). Participants were assigned to one of the training conditions and instructed to perform task analyses of five different tasks (making a piece of toast, making a cup of coffee, painting a door, making a phone call, and making Vetkoek - a South African main course). Questionnaire data (declarative knowledge) and task analyses (procedural knowledge) were coded on five criteria: hierarchical representation, stating high-level goal, stating plan, stating subgoals, and satisfaction criteria. Results indicated that participants identified some criteria (goals, subgoals) more often than others as being representative of HTA (hierarchical representation). Furthermore, the nature of the task had a greater effect on the knowledge acquired about HTA than the differences in training material at this early stage of learning. During initial training of HTA it is important that more detailed instruction materials be distributed to allow for greater understanding of HTA. This study informs research about various types of diagrams and also adds to the literature on training HTA.
Nanoparticle-mediated r-depression in the rotifer Brachionus manjavacas

(Georgia Institute of Technology, 2009-12) Hicks, Daniel

Nanotechnology research promises novel and practical applications of well-characterized materials. However, responsible development of the nanotechnology industry necessitates proactive research into the ecological responses of communities to the presence of nano-scale materials. I attempt to discern if and how the presence of inert nanoparticles at varying concentrations and size affects the fitness of populations of Brachionus manjavacas (Rotifera). Feeding fluorescently labeled 50 nm latex microspheres to rotifers produced dramatic fluorescence distributed throughout the females and their eggs. Fluorescent intensity was distinct from background epifluorescence exhibited by B. manjavacas, and increased with concentration, availability of food, and duration of exposure. Transfer of exposed maternal females and F1 offspring into nanoparticle-free environments demonstrated that these nanoparticles were rapidly cleared from the animals, and that the offspring suffered no significant effects from parental exposure. However, the population growth rate was depressed 50% in rotifer cultures exposed to 0.30 ug/mL of 50 nm particles, and 89% in cultures with nanoparticle concentrations of 1.14 ìg/mL. Nanoparticles of identical composition but of larger diameter (up to 3000 nm, comparable to algae cells, a natural food source), caused no reduction in population growth rate. These larger particles remained confined in the gut, implicating nanoparticle size as a critical factor in bioactivity. Causes of growth rate depression include, but are not limited to, a marked decrease in feeding behavior. Mode of entry is suspected to be either epithelial digestive-tract phagocytosis or introduction through cellular pores.
Graphene nanoribbon array fabrication by oxygen gas plasma etching through sub-micrometer porous filters

(Georgia Institute of Technology, 2009-08-07) Shaw, David

We investigate a novel method of fabricating a network of graphene nanoribbon structures. The process is a sharp departure from conventional nanolithographic techniques in both method and amount of time required. Epitaxial graphene prepared on single crystal 4H-SiC was etched with O2 plasma through 0.2 ìm porous filters adhered to the surface of the sample. Thickness measurements using ellipsometry and topological mappings using atomic force microscopy were conducted to ascertain the extent of graphene nanoribbon formation. Sheet resistance of the samples was measured using the four-point van der Pauw method to ensure the existence of electrical conductivity in the etched samples. Furthermore, the etch-rate of multilayer epitaxial graphene was determined.
Environmental Effects on Variable Practice of Example Formats

(Georgia Institute of Technology, 2009-05-07) Kishi, Roudabeh

There is a lack of women in mathematics-related fields. This might be due to stereotype threat, when a person performs worse than usual when presented with a negative stereotype because they are worried they will prove the stereotype to be correct (Steele, 1997). As practice schedules can affect performance (Carlson & Yaure, 1990), this experiment measured math performance after implementing blocked or random practice schedules and an activated or inactivated negative stereotype. Forty-eight college students learned probability from worked examples and practice problems and were tested on overall math performance and other aspects of learning. Results suggest that, in general, a blocked order tends to yield greater math performance, especially under the effects of a negative stereotype. Future research should examine retention, in addition to acquisition, of the learning materials.
Functional Neuroimaging Investigation of the Neural Mechanisms for Successful Feeling-of-Knowing Judgments

(Georgia Institute of Technology, 2009-05-04) Greenberg, Ronit

A feeling-of-knowing (FOK) is a sense of knowing that an item would be recognizable if seen again later, despite one’s current inability to recall that item from memory. An FOK judgment occurs after a memory search and is a prediction of future recognition. The current study aimed to: (1) determine the brain regions involved in successful (accurate) and unsuccessful (inaccurate) episodic FOKs; (2) replicate the ability of FOKs to predict recognition outcomes and recollection/know (R/K) judgments; (3) explore the different effects of familiarity and recollection on high and low FOKs; and (4) determine the effect of overlearning on FOKs and their ability to predict recognition and R/K outcomes. Nine younger adults (ages 18-26) participated in 2 experimental sessions (encoding and testing), separated by a 48-hour delay (n = 4 for fMRI data). The amount of exposure to the studied items (1 versus 3 presentations) was manipulated. Statistically significant results include (1) a repetition effect such that the words that were repeated during encoding have higher mean recall, mean FOK rating, mean recognition accuracy, and mean R/K than those words presented only once; (2) activity in the ventral lateral prefrontal cortex (PFC) for successful or accurate FOKs; (3) activity in the anterior PFC for accurate high FOKs; and (4) activity in the PFC and anterior cingulate for correctly recognized and remembered items. In future, additional participants are necessary to conduct further and more detailed analyses.
Development of a Cohesive Theory of Leadership

(Georgia Institute of Technology, 2009-05-04) Halter, Jeffery T., Jr.

Previous assessments of leadership have failed to fully take into account what leadership is. Therefore, the goal for this study was to combine existing theories into one cohesive theory. In this study, undergraduate psychology students (N = 21), were placed in groups of 3 and recorded during a modified game of "20 Questions." During the game, participants were observed and exhibited "leadership behaviors" were documented. Participants identified as leaders exhibited more leadership behaviors, but only as the experiment went on and no additional "power" was given to followers. Implications of results and possible means of improvement are discussed.
Detection of Respiratory Syncytial Virus DNA with Gold Nanorod Surface Enhanced Raman Spectroscopy Active Substrates

(Georgia Institute of Technology, 2009-05-04) Siemens, Katherine

Surface enhanced Raman scattering (SERS) is a powerful spectroscopic tool that can be used to identify and characterize compounds at low concentrations. Recent literature reports suggest that SERS may be applicable for the detection and identification of viruses present in biofluids. In this investigation, gold nanorod arrays were evaluated as SERS substrates with the specific purpose of probing spectral differences between single stranded (ssDNA) and hybridized, or double stranded (dsDNA) DNA. This was deemed as the first step in developing a SERS-based hybridization assay for viral identification. Hybridization was carried out both off and on the substrate surface to determine whether there are observable spectral differences from the two different methods of hybridization. Studies were also carried out to determine if it was possible to detect mismatched DNA pairs after hybridization had been attempted. Gold SERS active substrates were utilized instead of silver giving the advantage that these substrate do not oxidize under ambient conditions. It has also been found that ozone cleaning gold substrates before sample application increases the hydrophilicity of the gold, making the use of smaller sample volumes possible. Ozone cleaning the gold substrate after ample binding time has passed increases the SERS signal as well. It is believed that this cleaning immediately prior to SERS acquisition cleans the gold surface to a point where the plasmon being formed is more likely to move up the sample which increases the intensity of the SERS signal. In addition to examining the possibility of using gold instead of silver for the SERS substrates, a method allowing for 36 separate DNA assays to be run at one time was investigated. This is accomplished by creating wells with polymer. Up to 36 wells fit on one glass microscope slide meaning that anywhere from 1 to 36 DNA probes can be attached within individual wells. This allows for either 36 different biological assays for the same virus or 1 biological sample to be tested for 36 different viruses or virus strains.