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College of Sciences

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School of Biological Sciences

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School of Chemistry and Biochemistry

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School of Earth and Atmospheric Sciences

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School of Mathematics

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School of Physics

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Publication Search Results

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A Study Exploring the Relationship Between Racial Discrimination, Depression, Anxiety, and Stress on Sleep Quality

(Georgia Institute of Technology, 2021-12) Rampally, Lolasri

Prior studies have shown that discrimination experiences have a positive association on adults' symptoms of depression, anxiety, and stress as well as on their sleep patterns. Symptoms of depression, anxiety, and stress appear to be associated with age, with younger adults experiencing higher levels of discrimination than older adults. The findings of this study may aid in evaluating the validity of prior literature and also exploring this further by studying the relationship between discrimination and symptoms of depression, stress, and anxiety with gender as a moderating variable. The present study is the first to examine COVID-19's effects on symptoms of depression, anxiety, stress, sleep patterns, and discrimination, which may have been caused by the pandemic. A total of 582 people between the ages of 18 and 79 participated in this study. In part 1 of the study, participants were asked to complete online questionnaires such as DASS for symptoms of depression, anxiety, and stress, PSQI for Pittsburgh Sleep Quality Index, DI for discriminatory index, and general questions about how their lives have been affected by COVID-19. After 48 hours, the participants take part in the second part of the experiment, during which they complete a questionnaire about stress coping strategies and a memory test for the images they've seen in the first part of the experiment. Three hierarchical regression analyses are performed to investigate whether adding variables such as DI, age and gender could significantly increase the variance accounted for in the outcome/criterion variables (i.e., PSQI and DASS). While there is a statistically significant relationship between DASS and PSQI, DI and DASS with age as a moderator, and DI and DASS with gender, the inclusion of the interaction terms for DI and gender or DI and age were not statistically significant indicating that there is no interaction effect which explains variance above and beyond the two independent variables separately. Future studies may modify parts of this study to observe race-related differences, such as increasing the sample size or changing the DI by adding race as a moderator variable.
Overgeneral autobiographical memory in depression: a three-level meta-analysis

(Georgia Institute of Technology, 2021-12) Weiss-Cowie, Samuel Aaron

Overgeneral Autobiographical Memory (OGM) is a frequently studied phenomenon in major depressive disorder (MDD). Although there exist several meta-analyses on OGM and MDD, their emphasis on clinically diagnosed current depression leaves open question about the severity of OGM in subthreshold and remitted depression. In addition, numerous studies of OGM have remained unconsidered due to a focus on one testing paradigm, the Autobiographical Memory Test (AMT). To address these gaps, we conducted a meta-analysis on OGM in MDD that included remitted, subthreshold, and currently depressed samples and incorporated non-AMT studies. In addition, we used three level models for the first time, which enabled robust variance analyses including multiple effect sizes from each study while controlling for dependencies across those effect sizes. With results from a total of 67 published and unpublished works, ours is the largest meta-analysis to date on OGM in depression. We simultaneously identified decreased autobiographical memory specificity (g = -0.73) and increased categoricity (g = 0.77) for depressed individuals compared to controls. Moderator analyses suggested that OGM is more severe in current, clinical MDD than subthreshold and remitted depression, while OGM is similarly severe for positive, neutral, and negative memories. Our results resolve longstanding debate surrounding the relationship between valence and OGM while emphasizing the importance of utilizing a broader range of testing paradigms and considering non-clinical depression in future work.
The Role of Sleep Spindles and Theta Rhythms in Associative Memory Consolidation of Healthy Young Adults

(Georgia Institute of Technology, 2021-12) Tolosa, Anabella

The purpose of this study was to examine sleep EEG in healthy young adults ages 18-25 years old. The Dreem2 wearable device was used to collect data.
Motor Learning in a Goal-Oriented Visuospatial Task

(Georgia Institute of Technology, 2021-12) Williams, Erin Skyler

There have been numerous studies that investigate motor learning at large, but there is a lack of research focusing on three-dimensional visuospatial learning and action observation in the setting of a goal-oriented motor task. There are even fewer that test these variables while introducing a social component in which the subject must execute motor control based off another person’s directed movements. The objective of this study is to investigate how factors, such as action observation, social intention, motor control, and goal-oriented behavior impact motor learning of a subject during a structure building task. Twelve right-hand dominant subjects engaged with the researcher during two rounds (each consisting of 15 trials) with each round resulting in a static structure that the subject constructed by imitating the movements of the researcher. Half of the subjects completed this paradigm while wearing a transradial body-powered prosthetic simulator device on their right arm (experimental group) to test if the prosthesis altered motor learning. The research questions aimed to assess subjects’ ability to display evidence of motor learning throughout the task, if this evidence is associated with increased gaze position in the researcher’s quadrant, and if these trends remain consistent when subjects are wearing the prosthesis. Eye-gaze patterns, task completion time, performance and task errors, and behavioral observations were used as methods of data collection, and statistical analyses, including t-tests, sample means, and surface distributions, were performed to evaluate the hypotheses. Results revealed subjects in both groups demonstrated motor learning between round one and two, and while the addition of the prosthesis increased task completion time and error values, subjects within the experimental group were also able to demonstrate significant decreases in the latter round. In addition, eye-tracking data revealed increased gaze patterns on the researcher’s path of movement vs. the quadrant itself for the experimental group compared to the control group. This suggests that social intent and action observation are likely facilitating an increase in motor learning in subjects tasked with completing goal-directed movements with the unfamiliar prosthesis.
Clinical Indicators that Predict Motor Recovery Post-Stroke

(Georgia Institute of Technology, 2021-05) Noone, Amulya

One of the leading causes of long-term disability in adults is stroke. Stroke occurs due to disruptions in the blood supply in the brain resulting from a blockage or bleed. These disruptions can lead to impaired upper extremity motor function. Typically, patients participate in rehabilitation to regain lost motor function through training. However, it remains difficult to predict the expected level of recovery for each patient post-stroke. Improving prediction accuracy has the potential to increase the efficacy of therapy, influence therapeutic practices, and encourage stroke survivors to continue training. PREP2 is one algorithm that has shown promise in predicting upper-extremity outcomes in New Zealand. However, it is unclear if PREP2 can be successfully applied in the United States. The three goals of this study were to assess the feasibility of implementing PREP2 in the United States, determine whether currently collected clinical outcome measures could be used to better predict recovery post-stroke, and investigate relationships between nonmotor domains and motor recovery. To assess feasibility, we conducted a retrospective chart review of patients admitted with stroke to Emory University Hospital. We collected measures regarding stroke characteristics, patient demographics, and progression of recovery. Some of these measures include patient age, National Institute of Stroke Scale (NIHSS) scores, and Shoulder Abduction and Finger Extension (SAFE) scores. Using the collected data, Action Research Arm Test (ARAT) scores, a measure of upper extremity motor function, were estimated. Additionally, we conducted a correlational analysis to investigate the relationship between currently taken outcome measures and recovery post-stroke as well as between motor recovery post-stroke and nonmotor domains: speech and sensory impairment. Findings suggest it is feasible to implement PREP2 as the core metrics (e.g., SAFE, NIHSS) are collected on appropriate timelines. Additionally, SAFE scores were the only measure correlated with motor recovery post-stroke. We found no significant correlations between nonmotor domains and motor recovery. These findings are significant because they help refine the algorithm to ensure it is appropriate for the healthcare system in the United States. Additionally, research into nonmotor domains can add another layer to the algorithm leading to more accurate predictions of recovery.
An investigation into the multiple Type VI Secretion Systems of Enterobacter cloacae

(Georgia Institute of Technology, 2021-05) Wilson, Ashley

Enterobacter cloacae is a Gram-negative, opportunistic bacterial pathogen that is commonly acquired by patients in hospitals. The Type VI Secretion System (T6SS) is a harpoon-like apparatus that injects toxins into the cell envelop of neighboring bacteria to defend or compete for resources. It’s commonly found in a range of bacteria including Vibrio cholerae, Pseudomonas aeruginosa, and Escherichia coli. Previous research in this lab has shown that E. cloacae kills in a contact dependent manner and bioinformatic analysis found three vask genes, which encode for a protein in the Type VI apparatus. We created three single mutant strains (Δvask1, Δvask2, Δvask3) as well a double mutant (Δvask1Δvask3). These strains were tested in competition assays with target WT E. coli, with the survival of the target being indicative of E. cloacae killing ability. We show here that Δvask2 had no change in killing ability, Δvask1 and Δvask3 had some reduction in killing ability, and Δvask1Δvask3 had a complete reduction in killing ability. This initial result suggests E. cloacae in vitro killing ability is dependent on two T6SSs.
CCSP 2.0: An Open-Source Jupyter Tool for the Prediction of Ion Mobility Collison Cross Sections in Metabolomics

(Georgia Institute of Technology, 2021-05) Watson, Chandler Avery

Tandem mass spectrometric methods revolutionized the chemical identification landscape, allowing serums and molecules to be separated in two or more dimensions. Ion Mobility Mass Spectrometry workflows combined with liquid or gas chromatographic separation have continued to progress chemical identification and further increase the amount and confidence of these identities. Such advancements have also given birth to a new molecular descriptor: the Collision Cross Section, sparking heavy interest in the analytical-computational chemistry to compile these values for known molecules. The main shortcoming has been predicting the CCS value for new molecules such as Poly-Fluorinated Alkyl Sub-stances. Preliminary prediction software has revealed that predicting CCS values for this molecular class is possible, but it can prove temporally, computationally, and financially expensive between different licenses and genetic algorithm. This work combines open-source Python modules (NumPy, Mordred, Pandas, etc.) to construct an alternative workflow that is completely free and capable of running on a mid-specification laptop within a half hour. Using the M-H and combined M+H and M-H datasets taken from the McClean CCS Compendium, median prediction errors of 2.07% and 1.84%, respectively, were found using Support Vector Regression within 5 minutes on a mid-spec laptop, satisfying the 2.50% benchmark. This overall success illustrates the power and versatility of this workflow to produce low errors with datasets as large as 1300+ molecules and as few as 37. This script can be distributed on file-sharing sites like GitHub where other users may customize the free source code to fit their experimental needs.
Discovery of Monoclonal Antibodies for Diagnostics and Therapies Using Conjugate Virus-like Particle Vaccines

(Georgia Institute of Technology, 2021-05) Schroeder, Michelle

Monoclonal antibodies (mAbs) are highly specific antigen binding proteins that are used as biological reagents, therapeutics, and in rapid diagnostics. While mAbs have extensive potential applications, their means production for small molecules and conformationally specific peptides is difficult. Here, we use a method of mAb production in which we pair conjugate virus-like particle (VLP) vaccine with hybridoma technology to produce high-affinity mAbs against three classes of molecules 1) fentanyl derivatives, 2) SARS-CoV-2 peptides, and 3) α-amanitin and microcystin LR cyclic peptide toxins. We successfully produced broad and derivative-selective mAbs against eight fentanyl derivatives. We also showed early signs of success targeting neutralizing and mutant SARS-CoV-2 peptides with conformational specificity using a heterologous prime-boost strategy. Lastly, we produced high affinity mAbs for both α-amanitin and microcystin LR, two highly toxic cyclic peptides. The early success of mAb production against the variety of targets presented in this thesis shows the viability and exceptional versatility of conjugate VLP vaccines as a means to producing mAbs.
Sex-related differences in resolving proactive interference during associative memory tasks

(Georgia Institute of Technology, 2021-05) Quadri, Ayesha

Prior studies have shown that males and females perform differently on a variety of memory tasks. It is suggested that certain biological factors can lead to sex-related differences in cognitive decline, memory, and learning. The present study explores this further by examining the performance of males and females on associative memory tasks when exposed to proactive interference (PI). The findings of this study may aid in understanding the underlying mechanisms involved in overcoming interference and improving memory. This study utilized 49 individuals (F = 26, M = 23) between the ages of 18 and 77. The participants were asked to complete associative memory tasks while exposed to varying levels of interference (high interference, low interference, or no interference). During the encoding portion of the memory task, participants were asked to determine the ease in which two images presented together could be imagined. During the retrieval portion of the memory task, participants were asked to recall which associate category (face or scene) the presented object was most recently paired with in the encoding phase. Electroencephalography (EEG) data was also collected while the participants completed the memory tasks, but due to time-constraints and limitations introduced by the COVID-19 pandemic, this data was not analyzed. A 3x2 repeated measures ANOVA conducted found a significant main effect of interference on memory accuracy, but no significant difference in the effects of interference on the memory accuracy of both sexes. Additionally, no interaction between interference conditions and sex was found. However, a paired samples t-test found significant differences in memory accuracy between the three interference conditions used in this study. Given this, future studies may modify components of this study to observe sex-related differences, such as changes to the associative memory task or an increase in the sample size. In the future, the potential analysis of EEG data may shed light onto differences in neural activity between the two sexes when exposed to PI.
Single particle cryo-EM structure elucidation of a Photosystem II complex mimicking a critical step in photoinhibition

(Georgia Institute of Technology, 2021-05) Espy, Carolann Lindsay

Photosystem II (PSII) is an essential protein in the photosynthetic process that houses the oxygen evolution center, which is responsible for producing most of the oxygen in the atmosphere. In order to better understand PSII and its function, it is important to discern the structure of active PSII and the process of photoinhibition. Photoinhibition occurs when the extrinsic subunits are damaged due to overexposure to light, and are then removed, repaired, and replaced. The removal of these extrinsic subunits could be recreated with the help of a urea wash protocol, which removed subunits PsbO, PsbP, and PsbQ. The method used here to elucidate the structure of urea wash PSII, was electron cryo-microscopy (cryo-EM). Utilizing this method and a gentle purification of the protein, a 3D model of an important step in the repair of ‘photoinhibited’ PSII was obtained. Through testing multiple parameters during image processing, several models were generated with estimated resolutions ranging from 20.74 Å to the best estimated resolution of 9.05 Å (Figure 2).