Summer 2024

Paige Williamson

Advisor: Maja Šešelj

Fluctuating Dental Asymmetry and Great Ape Development

Fluctuating asymmetry (FA), which refers to differences in shape and/or size between the left and right side of the body, is an indicator of developmental instability and stress. While the body is still growing, conditions that require energy conservation (e.g., food scarcity, disease) usually manifest as a slowing down or interruption of growth across different tissues, to conserve limited resources for the most essential bodily processes. FA research in humans and non-human primates has primarily focused on the skeleton. In the dentition, more attention has been paid to defects known as linear enamel hypoplasia (LEH), which also correspond to periods of stress. Some research has detected fluctuating asymmetry in tooth size, however, no one has looked at perikymata, which are enamel growth increments visible on the tooth’s surface, and thus a constituent part of final tooth crown size.

Continuing the work started by Levi Raskin in his 2023 SSR project, and using a 3D scanned great ape skull sample from the Field Museum of Natural History, we will examine whether there is fluctuating asymmetry in perikymata counts and tooth crown diameters, and how it correlates with LEH. The scanned sample consists of 13 orangutans, 12 gorillas, 7 common chimpanzees and one bonobo, with 269 teeth cast. We will focus on permanent incisors and canines for which we have antimeres. The results will show whether FA in tooth size, if any, is correlated with LEH. Where perikymata counts for matching segments of crown height are available, the presence or absence of FA would indicate whether those differences are achieved through differential duration or rates of enamel secretion, respectively.

Sinthia Ahammed

Advisor: Alison Weber

Investigating Neural Responses from Manduca sexta Wing Nerve During Flight to Determine Sensory Encoding of Natural Behavior

Flying insects exhibit a remarkable capacity to recover from perturbations affecting their flight, demonstrating an ability to detect disturbances and initiate rapid feedback to maintain flight stability. A substantial number of mechanosensory receptors known as campaniform sensilla have been identified in the wings of flying insects, such as Manduca sexta, which  play a crucial role in encoding sensory information during destabilizing flight dynamics. However, there is a notable gap in the literature regarding the neural mechanisms governing insect flight during natural behavior. To address this gap, this study employs extracellular electrophysiology techniques to obtain neural recordings from the wing nerve of M. sexta with the aim of investigating the functionality of these small neural circuits, particularly in generating rapid reflexes during natural behaviors. Furthermore, this research seeks to elucidate the distinct neural signals which are produced in response to various types and magnitudes of perturbations. The insights gained from this research hold the potential to inform the development of advanced sensor systems in drones and airborne technology.

Ahado Ali

Advisor: Tamara Davis

Changes in Methylation Patterns impact Gene Expression

Background/ Importance: Genomic imprinting is the process by which only one copy of a gene, either maternally or paternally inherited, is expressed while the other remains silenced. DNA Methylation is an epigenetic mark that helps differentiate the two parental alleles and determine which copy gets expressed; this is done by covalently attaching a methyl group to the cytosines present in cytosine:guanine dinucleotides on one parental allele, resulting in a differentially methylated region (DMR), which often leads to the silencing of a gene. Once established, DNA methyltransferase 1 (Dnmt1) maintains methylation at these regions. The proper function of Dnmt1 and maintenance of differential DNA methylation are essential to the expression of imprinted genes and the normal development of mammals. The improper maintenance can result in developmental disorders such as Beckwith-Wiedemann and Angelman syndrome.

Question/ Hypothesis: A mutation in the intrinsically disordered domain of Dnmt1 (P-allele mutation) results in a loss of global DNA methylation during embryogenesis and perinatal death in homozygous mutant mice. Previous research has shown that homozygous P-allele mice experience decreased percent methylation at secondary DMRs compared to wildtype mice. This variability in percent methylation between wildtype and P-allele mice prompted the lab to investigate how changes in methylation influenced by the Dnmt1 P-allele mutation impacts the expression of imprinted genes. Because the P-allele mutation decreases methylation globally and at secondary DMRs, and methylation is associated with gene silencing, we hypothesize that mutant embryos with less methylation will express higher levels of imprinted genes.

Methods:  I will investigate this using techniques such as Quantitative Reverse Transcription PCR, with RNA derived from 18.5 dpc wildtype and P-allele mouse embryo brains to measure and compare gene expression levels in each of the samples. Preliminary data collected from two genes (H19 and Dlk1) normalized to housekeeping genes (CycloA and GAPDH) showed increased expression in P-allele mice as expected. More experiments will be conducted at different loci and in biological replicates to ensure the data is consistent and reliable.

Future Direction: Future steps for this project consist of analyzing two additional biological replicates from 18.5 dpc embryos and studying different developmental stages, such as 12.5 dpc, to determine whether expression levels remain consistent across development. Additionally, various tissue samples, such as the liver, can be investigated to assess whether changes in expression are global or tissue-specific. In the far future, the protein products of some of the imprinted loci can be explored to determine the mutation's impact on protein concentration.

Leila Byerly

Advisor: Adam Williamson

Building a CLN Knockout Cell Line Library for Functional Studies of the Batten Disease Proteins

Batten Disease is a debilitating neurodegenerative disease which often appears in children and can lead to severe symptoms including blindness, seizures, and early mortality. Batten Disease is a class of lysosomal storage disorders generally thought to result from inefficient turnover of intracellular debris. The disease is monogenic, associated with mutations in 13 mapped ceroid lipofuscinosis (CLN) genes with different, mostly unknown, molecular mechanisms of action which lead to similar symptoms in patients. To better understand the role and function of these genes and proteins in contributing to Batten Disease symptoms, we aim to uncover their relationship to phagocytosis and disruption of anti-inflammatory debris clearance. I will be conducting gene knockout studies using CRISPR-Cas9 to impede the functional version of the gene and mimic disease. I will then observe the effects of this model of disease on cellular processes through a series of various functional assays including live-cell imaging to compare knockout cells to wild-type controls in terms of their phagocytic and lysosomal function as well as other activities. These studies could be foundational to providing us with more information on how to treat each genetic cause according to its unique mechanism of disease; mutations that cause similar cellular dysfunctions may be treatable by similar regimens, whereas for those that disrupt the cell differently would require specialized approaches. We hope to clarify the relationship between these CLN proteins and the process of cell debris clearance, allowing us to move forward in understanding how these mutations lead to Batten Disease phenotypes and contribute new information that hastens development of new treatments for Batten Disease.

Jack Carlson

Advisor: Thomas Mozdzer

Measuring potential greenhouse gas production rates across genotype in Phragmites Australis rhizosphere samples exposed to global change factors

The common reed Phragmites australis is a globally distributed ecosystem engineer in coastal wetlands. Due to its cosmopolitan distribution and genetic diversity Phragmites has been used as a model organism to study the possible impacts of global change factors such as elevated CO2 and N on wetland ecosystems. Previous research has found that soil microbial communities vary significantly in Phragmites at the lineage level, with some preliminary data suggesting genotypic differences across populations. The bacterial associations in the plant rhizosphere may contribute to a genotype’s capacity to alter nutrient cycling and nutrient availability. While treatment level variation in soil microbial communities has been found, little is known about the level of variation in soil microbial communities within a population when sampled at high sampling rates (>3 samples per population), or in exposure to experimental treatments of elevated CO2 or N. To address this gap in knowledge I will collect soil samples associated with unique Phragmites australis genotypes from a long-term global change experiment at the Smithsonian Global Change Research Wetland, Edgewater MD, USA. I will develop a method to measure potential rates of methanogenesis and CO2 emissions. I hypothesize that microbial rates will vary by genotype and by environmental treatment. This research will provide a deeper understanding of the factors that affect greenhouse gas cycling and the potential impacts of near future global change. Methods developed in this study can be used for future research on Phragmites F1 genotypes from quantitative genetic experiment growing in the common garden at Bryn Mawr College.

Cynthia Clark

Advisor: Alison Weber

Analyzing Neural Activity Behind Proprioceptive Responses in Moths.

When insects are in flight, they use mechanosensory receptors on their wings, called campaniform sensilla (CS), to detect deformations of their wings due to slight changes in air currents, or perturbations, such as a sudden gust of wind or a collision. The CS enable them to respond to the perturbation by adjusting the position of their wings and abdomen, which allows them to remain stable. One insect in particular that uses CS is Manduca sexta, or the tobacco hawkmoth. Since M. sexta beat their wings about 25 times per second, we will use high-speed videography to record the moths in flight, and then use the software Anipose in DeepLabCut to track the motions of the wing during individual wingbeats. In addition, we will use electrophysiology to study the neural responses elicited in CS on the moth’s forewings (Pratt et al., 2017). Using a suction electrode, we will take extracellular recordings from the forewing nerve, which is comprised of the sensory neurons innervating the wing. Simultaneously, we will manually move the moth’s wing in the configurations recorded by the video, to identify which neurons are firing when the moth makes particular movements. So much of how action potentials are generated, processed, and responded to is unknown, even though everything that every animal, from the tiniest fly to humans, does is controlled by them. With these experiments, we hope to take a tiny step forward in understanding more about how they work. The next step in this research will be to determine a way to record the electrical signals of these neurons while the moth is naturally generating its own movements. Our current experiments will inform our understanding of neural responses during flight, but future work is needed to also understand how the system works in nature.

Jessica Cramer

Advisor: Gregory Davis

Identifying the Maternal Signal Responsible for Inducing Asexual Reproductive Fate:

The Davis Lab is investigating the pea aphid, Acyrthosiphon pisum, which exhibits a reproductive polyphenism: individuals of the same genotype develop into asexual and sexual forms depending on environmental conditions. During long summer days, aphids reproduce asexually via live birth (viviparously). As winter approaches, they give birth to future sexually reproducing offspring, male and female. Sexual females lay eggs (oviparous) that withstand the winter frost. During spring, these eggs hatch into asexually reproducing aphids. This switch is likely mediated by an unknown maternal factor dubbed “virginoparin” that’s delivered to embryonic progeny.

One candidate is juvenile hormone (JH), which is important for insect development. We have previously found JH to be sufficient to specify asexual fate in sexually fated oocytes when topically applied to their mothers. Building off a previous student’s work, which identified the gene Krh1 as a downstream target of JH signaling, and my own work, which demonstrated that Kr-h1 paralog 1 is upregulated when aphids are treated with JH/JH analogs, I hope to further confirm JH’s role in specifying asexual fate by looking for differential gene expression of JH between sexually and asexually fated embryos, using this Kr-h1 assay.

We are also investigating an alternative pathway as another virginoparin candidate. We plan to interfere with it to test the loss of function phenotype by using RNAi or ReMOT Control, a novel technique making use of vitellogenesis, allowing for the delivery of molecules from the mother’s hemolymph to developing oocytes’ yolk. 

Sarabjit Dhillon

Advisor: Adam Williamson

Designing Phagocytes that Target Correlates of Neurodegenerative Disease

Pathogenic and neurotoxic debris buildup contribute to brain decline in neurodegenerative diseases. Although current treatments for these diseases focus on symptom management, there are no medications that significantly slow disease progression. In this project, I will engineer anti-inflammatory phagocytic immune responses which promote cell ingestion of disease-causing material in the central nervous system and study if this proposed debris clearance method could be used to approach forming treatments for various neurodegenerative diseases.

I will build upon lab-synthesized engulfment receptors, Chimeric Antigen Receptors (CARs), which direct immune cells to ingest targets of therapeutic relevance through phagocytosis, the process by which the cells’ cytoskeletons reform to surround and engulf targets. In the Williamson group, there is a focus on programming phagocytosis for specific targets of interest through the development of Chimeric Antigen Receptors for Phagocytosis (CAR-Ps), which expand the reprogramming properties of CARs to macrophage lineages. My project aims to develop two novel CAR-Ps that effectively drive this process and express in cells using Gibson assembly and lentiviral transduction.

With better treatment options for neurodegenerative diseases needed, and the strain on medical resources to keep up with neurology demands in coming years, I hope to use my work to present new protective immune response strategies that may not only relieve symptoms of neurodegenerative decline, but also inhibit the diseases from progressing.

Hope Hsu

Advisor: Tamara Davis

Analysis of 5hmC levels in 5 dpp BL/6 brain DNA 

Within mammals lie imprinted genes. Usually, mammals have two copies, or alleles, of each gene, one from each parent, and both alleles have the possibility of being expressed. However, imprinted genes silence one parent's allele and express the other. This process is very important because incorrect gene expression can cause problems like cancers and developmental disorders. We can identify which copies are silenced or expressed because one of the alleles is tagged with a chemical modification called methylation. One allele is methylated while the other is not, resulting in areas called differently methylated regions (DMRs). DMRs are categorized in two ways based on the time of methylation acquisition and other characteristics. Methylation at primary DMRs is inherited from the parents at fertilization. Methylation at secondary DMRs is gained during embryogenesis. Primary DMRs are very symmetrical and have 90-100% of the methylated allele methylated while the unmethylated allele is only 0-10% methylated. Secondary DMRs have more variable methylation patterns and high levels of methylation asymmetry on the complementary DNA strands. 

During replication, the maintenance methyltransferase Dnmt1 modifies the complementary strand of DNA to mirror the template strand, therefore, the high levels of asymmetry or hemimethylation that we found are highly unexpected. We aim, through this analysis, to discover why secondary DMRs have significantly more hemimethylation than primary DMRs. We believe that this discrepancy is due to the oxidation of the methyl group at these sites. Oxidation could either prevent methyltransferase activity, or it could be recognized as damage and be replaced with an unmethylated nucleotide. We will use glucosylation of oxidized cytosine followed by methylation-sensitive restriction digestion and quantitative PCR to determine the amount of 5-hydroxymethylcytosine at secondary DMRs as compared to primary DMRs to test this hypothesis.

Kuankuan Hu

Advisor: Bárbara Bitarello

A Simulation Study for Detecting Balancing Selection under Diverse Mechanisms

Natural selection drives evolutionary changes that are reflected by different effects on the genetic structure of a population. Under circumstances where higher mean population fitness is associated with higher polymorphism, balancing selection (BLS) occurs and maintains the genetic diversity at the targeted loci, resulting in signatures such as excessive local heterozygosity, an excess of intermediate-frequency alleles, or excessive polymorphism-to-divergence ratios. The diversity in its mechanisms —  e.g., heterozygote advantage, negative frequency dependent selection, antagonistic selection, and fluctuating selection across time and/or space — and timescales contributes to the complexity in understanding the BLS. Classic signatures of BLS do not differ distinctively between mechanisms but vary significantly in response to the timespan that it has persisted.

Research shows that BLS balancing selection is more prevalent in the human genome than previously thought, as insight made possible by the development of methods tailored to detect BLS in the past decade. These methods have different requirements and optimal conditions for maximum statistical power. As a complement to review existing BLS testing methods, quantifying the power of the tests in a more uniform environment allows fair comparisons between methods and assists future decisions on selecting test(s) for given scenarios. Through forward evolution simulation by SLiM, different settings of a genome under BLS can be generated to test the statistical power of BLS detection methods. At the same time, this project will include modeling study of sexual antagonism, a BLS-maintaining mechanism that has not been extensively applied in models, in order to compare the power and limitations of current methods in various settings. With the results from valid statistical tools, future research can aspire to bring insights to research questions such as the strength and prevalence of BLS due to different mechanisms, the conditions for populational fitness benefits to overwhelm the costs under BLS, and stability of long-term BLS equilibria.

Fiona McHale

Advisor: Adam Williamson

Through Thick and Thin: The Effect of Microenvironment and Pathogen Consistency on Phagocytotic Decisions

Phagocytosis, the clearing of debris from organisms by engulfment, is a billion-year-old immunological process dating back to before the evolution of tyrosine phosphorylation based cellular signaling. The majority of research into cues for phagocytosis has investigated the role of this biochemical chemical signaling. However, as phagocytosis is older than this form of signaling, there is a likelihood that the physical cues from a phagocyte’s microenvironment play a role in its activation.

            A majority of previous research into phagocytosis has been conducted on stiff surfaces using glass beads to model pathogens. These materials do not accurately mimic the microenvironment that phagocytes operate in. Pathogens and tissue microenvironments can vary significantly between soft and stiff within an organism. As phagocytes are migratory, understanding their function in different environments is necessary.

How macrophages accomplish their varied tasks in physically distinct environments is a focus of my project. The material of the substrate I am using can be manipulated to change its consistency from soft to stiff. By using confocal microscopy, I will be able to precisely assess how the consistency of model pathogens affects which ones get digested and how the hardness of substrate can influence these choices. These findings will provide an important understanding of how to accurately research phagocytosis in lab environments and inform how immune system functioning is affected by an organism's biological history.

Asal Mogharehdehkordy

Advisor: Alison Weber

Analyzing Flight Dynamics in Response to Perturbations in Manduca sexta

In order to perform precise movements in response to the changing environment, animals need sensory feedback. Sensory feedback from the wings of flying insects is fundamental for producing stabilizing behaviors in flight. Mechanosensory neurons, which are responsible for sensory feedback, are scattered over the surface of insect wings and play a crucial role in detecting wing bending. Our work focuses on studying the behavior of the hawkmoth Manduca sexta in response to destabilizing perturbations to explain how a small and scattered population of mechanosensory receptors called Campaniform Sensilla effectively encodes the perturbations and enables stable flight. My summer research goal is to understand how moths respond to perturbations behaviorally. To achieve this goal, I will capture some videos using a high-speed camera to track and quantify moths’ behavioral responses to the imposed perturbations while the moth is held in a stationary position. Various destabilizing perturbations will be tested on the moth, including wind gusts of different magnitudes and collisions with different locations on the wings. Then we will analyze these videos with a software called DeepLabCut. It is expected that the moth will show compensatory and consistent reflexes to the perturbations. Via extracellular electrophysiology, we will then record neural responses from these mechanosensory nuerons while the moth is experiencing perturbations in order to identify which neural circuits are responsible for the observed behaviors. This research not only helps us deepen our understandings of sensory-motor integration in biological systems but also has the potential to contribute to the development of advanced robotic systems that benefit from rapid sensory feedback.

Max Monks

Advisor: Thomas Mozdzer

Investigating variation in Phragmites australis fecundity by genotype and exposure to global change

Coastal wetlands are vital to the protection of our coastlines from natural disasters and erosion. The common reed, Phragmites australis, is a marsh plant that is considered to be a model organism for studying plant invasions and responses to global change (Meyerson et al 2016, Eller et al 2019).  Previous studies have demonstrated rapid evolution of Phragmites in response to elevated CO₂ and N conditions, but little is known about the effects of global change exposure on reproductive fitness. Research in our lab has preliminarily demonstrated that the number of seeds produced in response to global change increases with N enrichment. While this demonstrates a treatment effect on seed production, it is unknown if this difference is solely due to global change factors or if reproductive output is influenced by genotype as well.

This study will determine if plant fecundity is impacted by genotype (G) as well as by exposure to elevated CO₂ and N (E).  We aim to determine if the response is driven by G, E, or a combination of those factors.

Phragmites australis seeds were collected in 2022 and 2023 on previously genotyped ramets collected from a long-term global change experiment conducted at the Smithsonian Global Change Research Wetland (GCReW) in Edgewater, MD. These plants are grown in conditions with elevated CO2, elevated N, both, or neither. Seeds will be collected from panicles and germinated in order to determine percent germination and death rates of seedlings at the G and E scale. This will allow me to determine if genotype and maternal treatment conditions affect the percent of seeds that germinate, and percent death of the seedlings. I hypothesize that fecundity will vary at the genotype level but that maternal plant treatment will have no effect on percent germination. This study will continue after the summer, observing growth rates of the viable seedlings.

Kira Morozova

Advisor: Bárbara Bitarello

Exploring models of balancing selection: mechanisms and timescales

Balancing selection (BLS) maintains adaptive polymorphisms in populations. It increases genetic diversity, ensuring that alleles do not go extinct. BLS can occur via several mechanisms: heterozygote advantage, negative frequency dependent selection, antagonistic selection (including sexually antagonistic selection), and selection that changes across time or space in a panmictic population. This research project will focus on exploring existing models pertaining to heterozygote advantage and sexually antagonistic selection.

Heterozygote advantage (HA) describes a situation in which the heterozygous genotype is more fit for survival than the homozygous recessive or homozygous dominant genotypes. Theory predicts the conditions under which a stable equilibrium can be achieved under a simple model of HA but, to our knowledge, the following remains unaddressed: what are the predictions for maintenance of genetic variation when there are differences in the relative fitness between males and females under HA? Should further investigation reveal that similar questions have been investigated in the past, we will focus on analyzing the techniques used in the relevant literature. Otherwise, we will use previous models used to make predictions about BLS, such as the one presented in Kidwell et al. 1977 or Fisher’s geometric model, as a basis for further manipulation during our inquiry.

The term sexual antagonism describes a case when males and females of a given genotype express a trait at the same rate, but the fitness of one sex is decreased in comparison to the other. Sexually antagonistic selection involves a trade-off between relative fitnesses of the sexes. Trade-offs like this can be one of the driving causes of BLS. Our exploration of this topic will include an assessment of how sexual antagonism models previously published in the literature can be implemented using forward population genetics simulators such as SLiM. Based on an evaluation of the results of the simulations, we will consider whether, and how, these models can be improved upon.

Anna Skiba

Advisor: Thomas Mozdzer

Heritable trait variation in seedling success and relative growth rates in Phragmites Australis

Coastal ecosystems provide many valuable environmental services such as acting as buffers against storms, protecting shorelines, and serving as the greatest carbon sinks on the planet. The globally distributed common reed, Phragmites australis, acts as an ecosystem engineer, as well as an invasive species in coastal ecosystems. Previous research has demonstrated evolutionary responses to near future conditions of elevated CO₂ and Nitrogen. The C-EVO at Bryn Mawr College has been investigating how rapid evolution in response to future global change factors influences carbon cycling and carbon storage. A key measure of evolutionary fitness is success in reproduction and survival of offspring. Little is known about how exposure to near future global change influences the germination and survival of Phragmites seeds. We collected seeds from genetically identified ramets of Phragmites australis from a long-term global change experiment at the Smithsonian Global Change Research Wetland, Edgewater, MD, USA. The seeds will be germinated to evaluate the influence of genotype and exposure to elevated CO₂ and N on growth and mortality rate. This research will provide insight into if genotypic variation and exposure to near future global change factors affect the success of Phragmites seedlings, how those possible effects can influence future genetic diversity of Phragmites australis populations, and what that could mean for carbon cycling and carbon storage in the ecosystem.

Jo Smith

Advisor: Thomas Mozdzer

Heritable Trait Variation in Leaf Toughness and Herbivory among Phragmites australis Genotypes from Two Populations

Salt marsh ecosystems provide many vital ecosystem services, but their existence is threatened by accelerating global change factors including rising concentrations of CO2, nutrient pollution, and human development. The globally distributed common reed, Phragmites australis, is considered a model organism for studying invasive species and plant physiology. Recent research from our lab group has demonstrated that exposure to both near future levels of CO2 and nutrient enrichment have reduced intraspecific levels of genetic diversity and altered plant traits suggesting that populations are rapidly evolving. Global change factors can also act as a selective agent on organisms, resulting in evolutionary responses in heritable trait variation in plant traits such as leaf toughness, a proxy for herbivore resistance. To evaluate the heritability of plant traits, unique genotypes of P. australis were collected from two populations in MD, USA, the Smithsonian Global Research Wetland (Edgewater, MD) as well as Parker’s Creek (Prince Frederick, MD) and were grown in a common garden at Bryn Mawr College. Common garden experiments allow researchers to evaluate traits by removing confounding environmental factors. Previous research has found that genotypes from SERC plants have tougher leaves, suggesting greater resistance to herbivory.  Unfortunately, not at genotypes were able to be measured last year.  This summer, I will measure leaf toughness on genotypes from both populations that had not fully developed last growing season. Data analysis comparing leaf toughness between individual genotypes and among the two populations will be evaluated against the future F1 leaf toughness traits to see what aspect of herbivory defense such as leaf toughness is a heritable trait response or an example of phenotypic plasticity in this species. This research aims to provide insights into which traits are heritable, to provide further insight to the evolutionary ecology of salt marshes.

Sarah Stanger

Advisor: Thomas Mozdzer

Linking Genotype to Trait Variation in Phragmites australis under Global Change Conditions

Coastal ecosystems provide many ecosystems services including carbon sequestration, nutrient removal, and aid in the protection of coastal environments from storms and rising sea levels. Given their position at the land-sea interface, these systems are also very sensitive to global change factors including increasing concentrations of carbon dioxide (CO2) in the atmosphere and nutrient enrichment. The common reed, Phragmites australis subs. australis is a foundation species and a model organism for studying plant invasions and physiological responses to global change. There is growing evidence that shifts in genetic variation within a population exposed to global change, or rapid evolution, might influence the ecosystem response. In order to differentiate phenotypic plasticity from genotypic responses, I will combine several unique data sets to explicitly link genotypic data with previously measured plant trait data from a long-term experiment at the Smithsonian Global Change Research Wetland, Edgewater, MD, USA.  An open top chamber experiment, simulating near future global change, was initiated in 2011 in a fully factorial design with two levels of CO2 (ambient or +340 ppm) and two levels of nitrogen concentrations (ambient or 25 g N m^-2yr).  Annual measurement of plant traits (plant height, stem diameter, biomass, herbivory, relative growth rates, photosynthetic rates, leaf area, specific leaf area, and flower presence) will be linked to plant genotypes from a previously published study from our group. By combining these disparate data streams, I will be able to differentiate between genetic variation (G), phenotypic plasticity to exposure (E), as well as GxE interactions. This research aims to bridge the fields of ecosystem ecology and evolutionary ecology to create better predictions of the response of foundation species to near future global change.

Sarah Stephens

Advisor: Adam Williamson

Investigating intracellular phagocytic signaling pathways using an in vitro recapitulation of the Draper and Shark system

The Williamson lab focuses on the process of phagocytosis, an ancient mechanism of clearing dead cells and debris. In the species Drosophila, phagocytic cells express the receptor Draper, which provides the “eat me” signal from the target to the cell via an intracellular signaling pathway. After the Draper receptor has come into contact with its target and then been activated by phosphorylation by the protein Src42a, it recruits a kinase, Shark. The protein Shark is the next step in initiating phagocytosis and is crucial for facilitating engulfment. While its abilities have been compared to similar proteins in T cells, the complete structure and binding capabilities of Shark have remained unknown. To further elucidate this signaling pathway, I will create an in vitro recapitulation of this system with the ability to quantify the interaction. These experiments will utilize a variety of methods to obtain pure protein stocks and reconstitute the system including affinity purification and size exclusion chromatography. Then, using these proteins, I will conduct in vitro binding assays. This immune pathway is incredibly essential and well-conserved throughout phyla, yet understudied; my work will help build understanding of these key immunological proteins.

Hannah Tobin

Advisor: Tamara Davis

Analysis of DNA methylation in wildtype and DNA methyltransferase mutant mice

For some mammalian genes, expression is based on the parent of origin. Either the mother’s copy is always expressed or the father’s copy is always expressed, while the other allele is silenced. Differential DNA methylation, where a methyl group is added to cytosine, is generally used to mark the DNA of a specific parent, so the mother’s and father’s DNA can be distinguished and their expression regulated accordingly. This is referred to as genomic imprinting. Misregulation of imprinted genes is responsible for human imprinting disorders, or diseases inherited in a parent-specific manner; this can be caused by genetic alterations or epigenetic defects that cause changes in which parent’s copy of a gene is expressed. Prader-Willi syndrome, Angelman’s syndrome, and Beckwith-Wiedemann syndrome are examples of human imprinting disorders. Better understanding the mechanism by which DNA methylation is acquired and maintained might lead to the future development of therapies for such diseases.

I am analyzing the consequences of a DNA methyltransferase mutation in mouse liver DNA. P allele mice have a lethal mutation in the Dnmt1 gene which is responsible for maintaining DNA methylation, reducing methylation levels and preventing the mice from surviving after birth. This summer, I will amplify the differentially methylated regions associated with imprinted loci from liver DNA derived from different developmental stages of wildtype and homozygous P allele mice. Then I will compare the liver methylation levels to levels of methylation in the brain, which were previously determined in the Davis lab, to determine whether activity of mutant methyltransferase is different in different tissue types. This research will lead to a better understanding of the mechanisms of gene imprinting and ultimately how variation in methylation impacts expression.

Anna Gray Ashton

Advisor: Jonas Goldsmith

Synthesis and Assembly of Polymeric Transition Metal Complexes for use in the Production of Clean Hydrogen Fuel via Photocatalytic Electron RelayHydrogen-powered fuel cells present an appealing alternative energy source due to their lack of harmful emissions. However, the most common method for producing hydrogen gas, steam reforming, uses methane and results in greenhouse gas emissions. One alternative method for producing hydrogen gas is water electrolysis, which can be energy inefficient and costly. This research aims to develop a novel method for water electrolysis using a polymer composed of transition metal complexes. This polymer contains both a photosensitizer (PS) complex and an electron relay (ER) complex. When the PS is excited by a light source, it can pass electrons to the ER, which then relays electrons to reduce the hydrogen atoms in water and generate hydrogen gas. The energetic advantage of this process is that linking the transition metals together in a polymer film allows for highly efficient electron transfer in the relay. This approach differs from the current method, which relies on the molecules randomly coming into close proximity with each other in solution to transfer electrons. This research aims to synthesize ruthenium, iridium, cobalt, and rhodium transition metal complexes containing vinyl bipyridine ligands, which can be linked together through electropolymerization. The polymers can then be assembled into layers to form the PS/ER water reduction system.

Juanita Beenyi

Advisor: Yan Kung

Structural analysis of the ternary complex of an archaeal mevalonate kinase.

Mevalonate kinase is a key enzyme in the mevalonate pathway found across bacteria, archaea, and eukaryotes, catalyzing the phosphorylation of mevalonate to mevalonate-5-phosphate using ATP. Despite its ubiquity, MK homologs vary significantly in their responses to feedback inhibition and in the structures of their ATP-binding regions. However, in some archaea, downstream metabolites do not inhibit MK, unlike in many other organisms. In addition, although crystal structures of MK bound to either substrate—mevalonate or ATP—have been solved, no structure of the ternary complex yet exists, leaving key questions about MK’s catalytic mechanism unanswered. This summer, I will conduct the kinetic and structural characterization of MK from the archaeon Methanocaldococcus jannaschii (MjMK) with the goal of generating new three-dimensional crystal structures, including the structure of the ternary complex, to provide insight into the MK mechanism. By exploring the structure of MjMK and its ATP-binding architecture, we also hope to gain an understanding of why MK in some archaea is resistant to feedback inhibition. This will yield a better understanding of how the structure of MK governs its activity and regulation.

Sachiko Bower

Advisor: Ashlee Plummer-Medeiros

Investigation of electrostatic interactions of membrane proteins and lipids

PqiA and YebS are proteins found embedded in the inner membrane of E. coli and other Gram negative bacteria, that are associated with the transport of phospholipids from the inner to the outer membrane. The mechanisms of PqiA/YebS and the phospholipid-protein interactions involved with lipid trafficking have not been widely studied, and the structures of PqiA/YebS remain unsolved. This project will investigate the roles of highly conserved polar and charged residues within the transmembrane domains of these proteins, which may contribute to the substrate binding site. Using AlphaFold predicted structures of both proteins, simulation systems will be constructed to investigate these key interactions of PqiA/YebS with membrane phospholipids. Phospholipid-protein interactions will be characterized by lipid residence time, bond distance, bonding atoms, lipid specificity, and type of interaction, using computational analysis. In addition to the analysis of wild type PqiA/YebS, simulations with proteins modified at the aforementioned residues will be constructed to observe lipid activity without key amino acids present. This determination of the mechanism of substrate selection will assist in the characterization of protein function that are critical to bacterial survival, contributing to the field’s understanding of bacterial life.

Abby Champlin

Advisor: Ashlee Plummer-Medeiros

Investigation of the role of the N-terminal extension of YebS on lipid and protein interactions

Gram-negative bacteria contain both an inner membrane and an outer membrane and bacterial growth relies on the efficient transport of phospholipids to the outer membrane. In Escherichia coli there are two protein complexes involved in lipid transfer (i.e., PqiABC and YebST). This research will be focused on the YebST complex or more specifically on YebS. YebS is an inner membrane protein while YebT, also known as LetB, is the bridging protein which physically connects the two membranes. The goal of this research is to further investigate possible interactions between YebS and phospholipids on an atomic level through molecular dynamics simulations using the predicted structure of YebS from AlphaFold. YebS has an N-terminal extension approximately 27 amino acids long that is predicted to be unstructured. Previous simulations of YebS in a phospholipid bilayer have shown that the N-terminal extension adsorbs to the cytosolic regions of YebS and potentially adsorbs to the phospholipid bilayer. This research will investigate the interactions between the YebS N-terminal extension, the phospholipid membrane, and the cytosolic regions of YebS. Phospholipid transfer to the outer membrane of E. coli is integral to the structural stability of the outer membrane and cell growth, thus since YebS is an integral member of the YebST lipid transfer complex it is also important to membrane stability and cell growth. An understanding of the structure and function of YebS, could lead to the development of more specifically targeted antibacterial drugs as the lipid transport complexes could potentially be targeted.

Carmen Gitchell

Advisor: Jonas Goldsmith

The Synthesis of Bimetallic Catalysts and Their Uses in Hydrogen Based Energy

The way that energy is created in the US usually produces carbon dioxide as a byproduct which is harmful to the atmosphere. Hydrogen energy can be made in a more green process though. The goal of the experiment in the future is renewable hydrogen-based energy as opposed to carbon-based energy. This project is focused on synthesizing a bimetallic molecule which works as a catalyst for the reduction of water using light energy, which produces hydrogen gas. One of the metal centers works as a photosynthesizer (absorbs energy and gets excited) which then transfers the electron to the electron relay. The electron is then transferred to an acid creating hydrogen gas. The transition metal complexes need to be close together for this to happen. One of the complexes will have an amine on it and the other will have a carboxylic acid. The two complexes are then connected through an amide bond. The work will involve synthesizing bipyridine molecules with amines and carboxylic acids to make the complexes.

Simone Gorman

Advisor: Bill Malachowski

Enantioselective Synthesis Using Birch-Hydroamination Reactions

Drugs that contain sp³ carbons are more successful in clinical trials than those that contain flat molecules due to the lack of solubility of flat molecules in the body and their tendency to react with many proteins. However, it is difficult to synthesize these quaternary carbons, and it is even more difficult to do so in an enantioselective manner. The Malachowski group has used the Birch-Heck sequence to achieve this goal in the past, but I’ll be looking to extend the strategy to hydroamination reactions. The Birch reduction-alkylation reaction produces a symmetrical diene, and an intramolecular hydroamination reaction would simultaneously generate a quaternary carbon stereocenter and a nitrogen-containing ring, which are incredibly common in successful drugs. The use of a chiral ligand in the hydroamination reaction would allow for the enantioselective creation of a chiral carbon during hydroamination. My research this summer will explore the use of different amines, different reaction conditions, and different chiral ligands in the Birch-hydroamination sequence.

Alex Harmon

Advisor: Patrick Melvin

Novel Synthesis of Fluoroformates Using a Sulfone Iminium Flouride Reagent

Fluorine plays a crucial role in drug development. It is often incorporated into pharmaceuticals to change a drug’s properties such as bioavailability and potency. The Melvin Group focuses on the production and applications of a novel sulfone iminium fluoride (SIF) reagent, which has been used to incorporate fluorine into molecules in under 60 seconds at room temperature. This project continues the investigation of SIF and its potential applications through the production of fluoroformates.  Currently, there are various methods to synthesize fluroroformates, but many of these techniques require highly toxic reagents, feature low yields, or require overnight reactions. The aim of this project is to first synthesize and isolate a scope of alpha-nitrile keto ester substrates. Our novel SIF reagent will then be applied to these substrates to yield various fluoroformates, in the hopes of increasing yields and decreasing reaction times. Easier synthesis of fluoroformates would allow for wider investigation into the applications of this highly useful class of organic molecule.

Suli Kamholtz-Roberts

Advisor: Ashlee Plummer-Medeiros

Investigation of YebS Transport System in Escherichia coli

Gram negative bacteria, such as Escherichia coli (E. coli), have a double membrane system to protect themselves from outside threats and keep functioning properly. The transport pathway of lipids to the outer membrane is important because it provides structural integrity for the bacteria. This project centers on the bacterial membrane protein YebS and understanding how it moves lipids between membranes. YebS is found in the inner membrane and works with YebT to form a lipid transport system. Together, YebS and YebT transport phosphatidylethanolamine (PE) and phosphatidylglycerol (PG), two major lipids in bacterial membranes. This function promotes outer membrane stability and subsequent cell growth. Without YebS functioning properly, the structural stability of the cell would be lost and the bacteria would not survive. YebS will be purified using affinity and size exclusion chromatography in detergent, then a Bradford assay will be conducted to further purify YebS from E. coli before testing it. Synthetic vesicles will then be used, these mimic the inner and outer membrane structure of gram negative bacteria. YebS will be reconstituted into synthetic vesicles and the lipid trafficking between vesicles will be measured to determine the function of the protein and the role it plays in lipid trafficking. PE and PG lipids will be transported from donor vesicle to acceptor vesicle by the YebS system. In E. coli, 75% of lipids are PE and 25% are PG. It is hypothesized that YebS will transport PE to the acceptor vesicle at a higher rate than PG because it is more abundant in E. coli. Future experiments will include testing the rate of lipid transport when adenosine triphosphate (ATP) is added and under various pH conditions. This research will further scientific understanding of the YebS transport system and aid in future development of antibiotics that target lipid transport.

Jude Kim

Advisor: Yan Kung

Structural basis of GGPP inhibition in Saccharomyces cerevisiae (yeast) MK

The mevalonate pathway uses seven enzymes to synthesize precursors for a variety of molecules, including steroids and isoprenoids. Mevalonate kinase (MK), the fourth enzyme of the pathway, binds substrates mevalonate and ATP to catalyze the phosphorylation of mevalonate. MK is competitively inhibited with respect to ATP by various downstream products of the pathway, including isoprenoid precursors and isomers isopentenyl pyrophosphate (IPP, C₅) and dimethylallyl pyrophosphate (DMAPP, C₅) as well as isoprenoid intermediates geranyl pyrophosphate (GPP, C₁₀), farnesyl pyrophosphate (FPP, C_15­), and geranylgeranyl pyrophosphate (GGPP, C₂₀). However, these inhibitors have notably different structures than ATP, raising the question of how MK accommodates such different structures of varying sizes in the ATP-binding site. Previous work by the Kung lab has obtained structures of MK from Saccharomyces cerevisiae (ScMK) bound to IPP, DMAPP, GPP, and FPP, but the structure of ScMK bound to GGPP has not yet been solved. Solving the structure of ScMK bound to GGPP will complete the current structural data of ScMK bound to its inhibitors. GGPP is also of particular interest because its carbon chain is the longest of all known inhibitors, yet it is unclear how ScMK adjusts for the longer chain. Inhibition data exists for GGPP, but without a solved structure of GGPP bound to ScMK, it is unclear exactly how structure correlates with binding affinity. Understanding this information will allow for better insight into the inhibition profile of MK and would be useful in the development of MK-inhibiting drugs. To answer these questions, I will first express and purify ScMK and confirm its activity using kinetics experiments, comparing results to previous data obtained by the Kung lab. I will then crystallize ScMK with GGPP to obtain its structure using X-ray crystallography. 

Maya Kumar

Advisor: Bill Malachowski

Development of Enantioselective Drug Intermediates Through Birch Alkylation Reduction

Completely flat carbon structures don’t make very good drugs. Research has shown that tetrahedral carbons and chiral centers in molecules allow for more selectivity and better bioavailability. This summer in the Malachowski Lab I will work on different methods of efficiently synthesizing tetrahedral chiral carbon structures that through desymmetrizing reactions can, if adapted, produce different enantioselective derivatives. The initial structures are made starting with commercially available ethyl benzoate and conducting a Birch reduction-alkylation reaction to add an alkyl chain with a nitrile group. The nitrile group will then be reduced. The molecule will then be potentially be desymmetrized using a transition metal catalyst to produce a chiral carbon and potentially create stereoselectivity through the use of chiral ligands on the catalyst.

Nuha Mohammed

Advisor: Patrick Melvin

Synthesis of Primary Carbamoyl Fluorides via a Modified Lossen Rearrangement

Fluorine plays a significant role in the pharmaceutical industry. Its incorporation in drug design can influence a molecule's acidity, conformation, lipophilicity, and metabolic stability. Despite fluorine’s crucial role in drug development, installing fluorine atoms still poses a difficult challenge. Given this concern, the Melvin Lab Group has created a novel sulfone iminium fluoride reagent, known as SIF, which is capable of performing effective deoxyfluorination reactions at room temperature in less than 60 seconds. Using this fluorinating reagent, I will ultimately be synthesizing primary carbamoyl fluorides following a modified Lossen rearrangement of hydroxamic acids. My work specifically focuses on developing a variety of hydroxamic acids that can participate in the Lossen rearrangement as well as optimizing the reaction conditions to maximize the yield of primary carbamoyl fluorides.

Charli Parsons

Advisor: Bill Malachowski

Exploration of the Intramolecular Pd-Catalyzed Hydroamination of a Birch Ester Cyclohexadiene

Heterocycles, especially those containing nitrogen, are structures commonly found in pharmaceuticals; therefore, developing efficient and selective synthetic pathways to generate them is crucial. Previous work in the Malachowski lab has explored the possibility of synthesizing these nitrogen-containing heterocycles by conducting hydroamination reactions on the products of the Birch reduction-alkylation, the hallmark reaction of our lab. Building on this work, we will attempt to expand the scope of the hydroamination reaction, yielding a variety of bicyclic structures with quaternary carbons, a particularly challenging carbon to create. Additionally, we hope to carry out mechanistic studies in order to better understand the reaction pathway, rendering it a more useful tool for our lab in the future.

Anna Roumiantsev

Advisor: Yan Kung

Structural Analysis of Substrate Binding in Human Mevalonate Kinase

The mevalonate pathway is a metabolic pathway that is responsible for the production of the precursors to isoprenoids, the largest and most diverse class of natural products that are used as drugs to treat different diseases. Mevalonate kinase (MK) catalyzes the ATP-dependent phosphorylation of mevalonate and is a key enzyme of the mevalonate pathway as it is a primary target of regulation. Although crystal structures of various MK homologs are available, none depict both mevalonate and ATP substrates bound to the enzyme. For human MK, structures of the enzyme bound to either ATP or mevalonate have also not been determined. In this work, I will crystallize MK from Homo sapiens (HsMK) to determine its structure bound to mevalonate and ATP or ATP analogs. Studying the crystal structure of the HsMK active site bound to these substrates will allow us to have a better understanding of MK catalysis and regulation.

Bernie Schintz

Advisor: Jonas Goldsmith

Investigation of Photoreduction Via the Electropolymerization of Ruthenium, Iridium, and Cobalt Transition Metal Complexes 

The Thin Layer Team in the Goldsmith lab focuses on producing hydrogen gas without the dependence on nonrenewable resources. Previously, hydrogen production via water photoreduction has been performed using catalytic systems composed of metal complexes which act as photosensitizers (PS) and a separate electron relay (ER) molecule. The ER quenches the excited PS through electron transfer, creating a reactive species which will reduce protons to hydrogen gas. These components have been studied in solution; however, electron transfer rates depend on distance. This project focuses on the synthesis of iridium, cobalt, rhodium, and ruthenium complexes containing vinyl substituents allowing for electropolymerization. Layering the synthesized polymers allows the complexes to be in close proximity, increasing electron transfer rates. Research aims to investigate how to structure the photosystem through cyclic voltammetry to ensure efficient photosensitizer and electron relay behavior from metal complexes. Since the complex’s photophysical and electrochemical properties depend on its ligands, ligands containing monovinyl and divinyl substituents in different positions will continue to be synthesized and investigated. Research aims to create an efficient photosystem via electropolymerization, techniques that have never been combined in such a manner, highlighting a new avenue of synthesis for hydrogen production.

Eujeong (Sal) Shin

Advisor: Patrick Melvin

Expanding the Use of Sulfone Iminium Fluoride Reagents in the Synthesis of Diverse Fluorinated Molecules

Fluorine is widely used in pharmaceutical and medicinal chemistry for introducing significant modifications to the molecule’s conformation, lipophilicity, solubility, pKa, and metabolic stability. These unique and beneficial properties that fluorine imparts has seen the incorporation of this powerful element into various drug motifs. The Mevin group has previously developed novel sulfone iminium fluoride (SIF) reagents that facilitate efficient deoxyfluorination reaction with high yields in only 60 seconds. Recently, I contributed to a project that took amidoxime substrates and rearranged those to novel fluoroformamidines using SIF reagents. The project this summer will focus on expanding the usage of those same fluoroformamidine products and the exploration of other interesting fluorinated products.

Tiffany Xue

Advisor: Jonas Goldsmith

Synthesis of bimetallic transition metal macromolecules for photosensitizer and electron relay pre-connection

The transition towards a low-carbon future necessitates the development of environmentally friendly energy sources, including green hydrogen. However, current hydrogen production methods emit substantial amounts of greenhouse gases, rendering them unsustainable. Electrolysis of water offers promise as a green hydrogen production method, but it suffers from high costs and low output. To address these challenges, our laboratory aims to enhance the photocatalytic water reduction system, thereby increasing hydrogen output. In this system, a light-trapping Photosensitizer (PS) rapidly excites and transfers electrons to an Electron Relay (ER). To establish an effective connection between PS and ER within a limited timeframe, we bring together PSs and ERs through amide coupling, accomplished by synthesizing transition metal macromolecules, with carboxylic acid one carbon away on either PS or ER and amine on the other. Previously we have achieved carboxymethylation. This summer we aim to achieve aminomethylation and improve the procedure with better purity and yield. This research has the potential to make a significant impact on the energy sector and the environment by reducing greenhouse gas emissions and contributing to global climate goals. Additionally, the mechanism employed to attach groups onto the original molecule to establish connections holds further potential for application in other synthesis cases.

Zahraa Zamir

Advisor: Yan Kung

Structural Modification of Cofactor Specificity in HMG-CoA reductase​

The mevalonate pathway is a major metabolic pathway in biology consisting of 7 enzymes responsible for the formation of isoprenoid precursors. Isoprenoids are a diverse class of natural products that can be utilized in many different industries, including but not limited to drug development. HMG-CoA reductase (HMGR) is the third enzyme of the pathway and catalyzes the committed step, the reduction of HMG-CoA to mevalonate. This reaction requires redox cofactors, either NADH or NADPH, where cofactor preference varies between different HMGR homologs. My research aims to develop a molecular understanding of the structural basis of cofactor preference. Previous research in the lab has shown that switching a short ‘cofactor helix’ between two HMGR homologs with different cofactor specificities also switches cofactor preference. Here, we have attempted to identify which amino acid residue(s) in the cofactor helix play a determining role in conferring cofactor specificity. We have performed site-directed mutagenesis of HMGR from Streptococcus pneumoniae (SpHMGR), which has a cofactor preference for NADPH. Our mutagenesis results indicate that changing specific amino acid residues does indeed change cofactor preference, with different mutants showing greater activity using NADH than NADPH. Through this work, we have identified specific amino acids of the cofactor helix that play key roles in conferring cofactor specificity in HMGR.

Paprika Chen

Advisor: Dianna Xu

Simulation and Visualization of Reflective Surfaces in Game Design Using Blender and OpenGL

In the field of computer graphics and game design, realistic reflections are crucial for creating immersive and visually compelling environments. This research aims to explore and implement advanced techniques for simulating reflections on various surfaces using Blender for 3D modeling and OpenGL for real-time rendering. Our primary focus will be on outdoor reflections, specifically on the simulation of a lake surface reflecting a small island with static objects, and later dynamic elements.

The project will begin with the construction of a simple 3D scene in Blender, featuring a small island within a still lake. Initially, we will assume the lake surface to be static and write shaders to simulate reflections on both the sky and the lake surface within the cubemap. This involves generating a skybox that captures the environment in Blender and applying it to the reflective surfaces in OpenGL.

The next phase will extend this approach to include reflections of static objects on the island, such as houses and trees, using the environmental mapping technique. By accurately calculating and rendering these reflections, we aim to achieve a realistic representation of models in the environment. Simultaneously, we aim to simulate lighting effects that more closely resemble sunlight and apply them to the surface of the lake to achieve better reflection and diffuse reflection effects.

Subsequently, the research will explore the inclusion of dynamic elements, such as a character that can move around the island and be reflected on the lake’s surface. This will involve more complex calculations and rendering techniques to ensure real-time performance and visual fidelity.

Paprika Chen is responsible for modeling test scenes in Blender, adding materials, and creating pictures using for cubemaps of skybox and lake reflections. In later stages, Paprika will continue with modeling and texturing in Blender, and will assist Yue Chen with the implementation of cubemap reflections in OpenGL.

By the end of this research, we expect to have developed a comprehensive framework for simulating both static and dynamic reflections in outdoor environments, contributing valuable insights to the Bryn Mawr Community and the broader field of computer graphics.

If progress allows, we will also explore the implementation of indoor mirror reflections, such as those in bathroom mirrors. This will extend our techniques to handle the unique challenges of indoor reflective surfaces, further broadening the applicability and impact of our research.

Yue Chen

Advisor: Dianna Xu

Simulation and Visualization of Reflective Surfaces in Game Design Using Blender and OpenGL

In the field of computer graphics and game design, realistic reflections are crucial for creating immersive and visually compelling environments. This research aims to explore and implement advanced techniques for simulating reflections using Blender for 3D modeling and OpenGL for real-time rendering.

The project will begin with the construction of a simple 3D scene in Blender, featuring a small island within a still lake. Initially, we will assume the lake surface to be static and only simulate reflections on both the sky and the lake surface within cubemap. This involves generating a skybox that captures the environment in Blender and applying it to the reflective surfaces in OpenGL.

The next phase will extend this approach to include reflections of static objects on the island, such as houses and trees, using the environmental mapping technique. By accurately calculating and rendering these reflections, we aim to achieve a realistic representation of models in the environment. Simultaneously, we aim to simulate lighting effects that more closely resemble sunlight and apply them to the surface of the lake to achieve better reflection and diffuse reflection effects. Rather than focusing on detailed modeling, we will concentrate more on creating more efficient and realistic shaders.

Subsequently, the research will explore the inclusion of dynamic elements, such as a character that can move around the island and be reflected on the lake’s surface. This will involve more complex calculations and rendering techniques to ensure real-time performance and visual fidelity.

This project not only aims to enhance the technical understanding of reflective surface simulation in game design but also seeks to provide practical solutions that can be utilized in real-world applications. By the end of this research, we expect to have developed a comprehensive framework for simulating both static and dynamic reflections in outdoor environments, contributing valuable insights to the Bryn Mawr Community and the broader field of computer graphics.If progress allows, we will also explore the implementation of indoor mirror reflections, such as those in bathroom mirrors.

Keywords: Reflection simulation, Blender, OpenGL, game design, computer graphics, 3D modeling, real-time rendering, cubemap

Rosa Bieber-Stanley

Advisor: Arlo Weil

Investigating Features of Laramide Deformation and Shortening on the Colorado Plateau

The Rocky Mountain system of Western North America, formed primarily by the subduction of the Farallon plate under the North American plate, is defined by two major tectonic systems, the Sevier and Laramide belts, which overlap temporally and spatially. The Laramide belt has a thick-skinned style with basement cored arches of various orientations that were uplifted along high angle reverse faults. The Laramide is unusual because it involved the transfer of stress far inboard into the continent. While various hypotheses, including flat slab subduction, have been posited for driving Laramide uplifts, the causal relationship between subduction style and the style of Laramide deformation is not yet fully understood.

The Colorado Plateau of the Four Corners region acts as a semi-rigid body within the North American plate that records a number of subtle Laramide structures. To help develop a more robust understanding of Laramide deformation, we will travel to the Colorado Plateau and surrounding areas to measure deformation structures such as minor faults and tectonic stylolites. We will also collect rock cores for paleomagnetic analysis. Data collected from analysis of these field and laboratory measurements will be used to establish shortening directions for Laramide deformation. However, to properly interpret these past shortening directions in the context of Laramide tectonism, the presence of vertical axis rotation must be assessed using paleomagnetic analysis.To do this, rock cores will be drilled in the field from Mesozoic red bed sandstones that contain abundant ferromagnetic minerals. In the laboratory, thermal demagnetization techniques will be used to iteratively strip away overprinting magnetic signals to identify the characteristic magnetic component that was recorded contemporaneously with the rock's formation. The magnetizations will then be used to quantify the distribution of relative vertical axis rotation between various Laramide arches in the Colorado Plateau region, and ultimately to correct our interpreted shortening directions to their orientations at the time of Laramide tectonics convergence. In order to properly interpret the significance of these results, rock magnetic experiments will be done to identify the mineralogy and granulometry of the samples to better understand the origin and significance of the magnetic remanence carriers. Ultimately, these data will further our understanding of how Laramide-related subduction resulted in the deformation styles observed in the Rocky Mountain system.

Malin Just

Advisor: Pedro Marenco

Investigating the temporal and spatial variation in the physical characteristics of mud-mounds in Early to Middle Ordovician reefs of the Ibex Succession, Utah, USA.

Reefs as we know them today are at risk due to ocean acidification and coral bleaching. To better understand how these reef environments might change as a result of these processes, researchers can gain insights from fossil reefs. The fossil record reveals multiple transitions from times during which reefs were largely built by microbial activity to those when reefs were constructed by animals. Fossil reefs located in the Ibex region of west central Utah represent different reef-building intervals during the Ordovician Period. These reefs were formed about 480 million years ago during the Early to Middle Ordovician and are characterized by dome-shaped build-ups of mud known as mud-mounds, some of which may have been built by microbial communities. The physical dimensions, spacing, frequency, and shape of the mounds vary between reef units.

In order to properly visualize the evolution of Ordovician reefs, it is helpful to map the physical characteristics of each unit. During this project, I intend to investigate how the frequency, physical dimensions, and spacing of mud-mounds vary temporally and develop a model to represent Early to Middle Ordovician reef-building environments in west central Utah to answer the following questions: How do the physical characteristics of mud-mounds vary in the Ibex Succession? What might these patterns reveal about Early to Middle Ordovician reef building environments in the Ibex Region?

To create the model, I will use GPS points of mounds from seven outcrops at three distinct geographical sites covering a time period stretching from the Early to Middle Ordovician to geocode the sites of each mound and mound unit. We mapped transects containing about four mounds each and then expanded those transects using drone footage to gain a wider view of the entire unit. I will use this footage to compliment the mapped dimensions of mounds and mound spacing. This data represents seven temporally unique instances of reef growth within the Early to Middle Ordovician. After quantifying and digitizing field data and observations and metadata from the drone footage, I will link the data for each mound to GPS points of the mounds. I will then map all of the data using ArcGIS. Previously collected petrographical and geochemical data for the mounds will be added to the geocoded points to create as high of a resolution model as possible. Using the GIS maps, drone footage, and digitized field notes, I will create a model for changing reef geometries and the depositional environments during the Early to Middle Ordovician Period. Comparing the results of my project to the development of modern reefs in the age of ocean acidification will help us understand what modern reef environments may look like without living corals.

Sonia Nicholson

Advisor: Arlo Weil

Analyzing Laramide Deformation and Paleo-Stresses in the Colorado Plateau

The Rocky Mountain tectonic system formed as a result of the eastward subduction of the Farallon Slab beneath the North American Plate between about 120 and 50 million years ago. This long-lived phase of subduction drove deformation far into the Rocky Mountain foreland basin, forming the Sevier and Laramide belts, which overlap temporally and spatially. The thick-skinned Laramide deformation, which is today located far inboard from the paleo-plate margin, contrasts with the earlier thin-skinned Sevier deformation, which is thin-skinned in style and located closer to the paleo margin. By studying Laramide structures exposed in the Colorado Plateau region, we will contribute to the understanding of the shortening history of the region, and ultimately how the resultant stresses produced by Laramide-style subduction caused the deformation styles observed in the Colorado Plateau/ Four Corners region. 

This project aims to further quantify the shortening direction for Laramide deformation in the Colorado Plateau/ Four Corners region. To do this the Anisotropy of Magnetic Susceptibility (AMS) will be used on Mesozoic red beds collected in the field later this summer. In undeformed rocks, the easy-axes of magnetic susceptibility are generally randomized. However, once a rock starts to undergo tectonic shortening, the magnetic susceptibility axes tend to rotate into a preferred orientation that is indicative of the applied stress. Therefore, the AMS measurements can be used as a proxy to infer shortening directions. In addition to AMS, structural deformation indicators, such as minor faults, widespread fracture and vein sets, and tectonic stylolites will be measured in the field and analyzed to quantify the orientation and spatial distribution of paleo-shortening directions. These structural deformation indicators have previously been interpreted to record Laramide-related layer-parallel shortening and therefore can be used to infer paleo-stress directions from the time of Laramide tectonism. Combined with ongoing paleomagnetic analysis to determine the degree of vertical axis rotation across the sampled region, our interpreted shortening directions will be used to test existing models that link Laramide-style subduction to the structural styles observed today across the Laramide system.

Sofia Prieto

Advisor: Katherine Marenco

Investigating Lower-Middle Ordovician Reef Fabrics Using Grid Analysis and Petrography

Reefs during the Early-Middle Ordovician Period (~485 to 460 million years ago) experienced a significant transition from microbialite dominance to increased contributions from metazoans (animals) such as sponges. My summer research is part of a broader project which aims to quantify the contribution of microbial communities to reef-building from the Early Ordovician into the Middle Ordovician in an effort to understand how ancient reef ecosystems evolved in response to environmental and biological changes. I aim to test the hypothesis that sponges became more significant contributors to reef fabrics over time.

We traveled to the Ibex region of western Utah, which contains multiple reef-bearing rock units from the Early-Middle Ordovician Period. We used a grid sampling technique in which a grid frame was placed on an exposed mound surface in order to systematically record the presence/absence and spatial distribution of sponges, receptaculitids (a sponge-like animal), suspected microbialite textures, and fossil fragments within a 25 cm x 25 cm area. This summer I will digitize the grid results, investigate patterns in our new data, and compare them with previously collected data. With these additional grid results, we have grid data from every mound interval in the Lower through Middle Ordovician succession in the Ibex area. In addition, physical samples were collected from representative mounds. In the lab, I will prepare thin sections from a subset of these samples for petrographic analysis. I will use a petrographic microscope to examine the microbialite fabrics and sponge fossils on a smaller scale. My goal is to compare data from each unit in order to identify changes in overall reef fabric, suspected microbialite textures, and the abundance of sponges within the reefs. This research will contribute to our understanding of the underlying biological and environmental dynamics that facilitated the transition from microbial to metazoan dominance in Early-Middle Ordovician reefs and set the stage for further metazoan involvement in reef frameworks.

Noshin Haque

Advisor: Leslie Cheng

Stock Price Prediction of Netflix

This summer, I want to work on a research project based on predicting stock prices of a company like Netflix, one of the leading companies that is dominating our economy currently. A lot of people use Netflix as their primary source of entertainment: streaming series, movies etc. Therefore, it is possible for us to make large profits by estimating Netflix's stock price. Data Collection and processing would be a significant part of my project. Then I will analyze the stock price data and will be using pricing models such as Multi Period Binomial models and Geometric Brownian Motion to predict stock prices.Throughout the summer, in order to find my solution, I will research several pricing models in further detail.My initial plan is to review the course materials that I learned in Mathematics of Financial Derivatives. This includes a comprehensive review of topics such as risk management, portfolio theory, and basic pricing models. Additionally, I am eager to delve deeper into advanced pricing models like binomial pricing models, which play a crucial role in accurately forecasting stock prices. I would also learn about softwares that will help me to model stock prices and may use R-Studio to help in visualizing my data through charts and histograms. The stock market is a dynamic, intricate system that is impacted by a wide range of variables, including business performance, industry trends, geopolitical events, and economic indicators. Accurately predicting stock prices has proven to be a challenging task for both researchers and investors.The result of predicting them accurately can lead us to gain profits.

Umme Rafiun Haque

Advisor: Leslie Cheng

Optimal Play in Combinatorial Games

This research delves into the applications of game theory in combinatorial games, aiming to provide a comprehensive understanding of the strategic interactions and decision-making processes within these mathematical models. A combinatorial game is a game with the following characteristics: there are only two players, there are a finite number of moves, it is a zero-sum game (a game that ends with a win for one player and a loss for the other player or a tie/draw for both players), it is deterministic (there are no random moves), and there is perfect information among the players (each player is fully aware of the moves made in the past and their available options from their current position).

The primary goal is to analyze how rational decision-makers interact in combinatorial games, evaluating how their choices, influenced by mutual awareness, impact the outcomes. By studying various combinatorial games in-depth, this project examines the strategies employed by players and the resulting dynamics, offering insights into the patterns and principles that govern strategic behavior. 

Furthermore, game theory is vital in the real world as it offers a framework for comprehending strategic interactions among individuals, businesses, and countries, facilitating improved decision-making in competitive scenarios. It aids in predicting and explaining behaviors across various fields, underscoring its significance in economics, politics, and social sciences, and leading to more effective policies and strategies.

Jingxuan (Christine) Yang

Advisor: Leslie Cheng

Modeling the Spread of Influenza in Urban Environments Using Two-Dimensional Random Walk Simulations

As a highly contagious respiratory illness, influenza presents significant public health challenges due to its rapid transmission and seasonal fluctuations. This research aims to explore the patterns of influenza spread in urban environments using random walk models, a statistical tool that represents paths consisting of a series of random steps.

In this project, we will employ two-dimensional random walk simulations to model the spread of influenza in an urban setting. Each individual in the simulation is represented as an agent that moves randomly in a two-dimensional grid, mimicking real-life human movement patterns. We will begin by explaining the theory of the two-dimensional random walk. Subsequently, we will incorporate various factors such as contact rates, population density, and movement patterns derived from real-world data from sources like the CDC and WHO. The significance of this research lies in its potential to enhance our understanding of disease transmission in urban environments, leading to more effective public health interventions

Anvita Deshpande, Lily Muehlenhard & Can Somer

Advisor: David Schaffner

Studying the influence of magnetic obstacles on plasma magnetic fields and wave fluctuationsPlasma is a superheated gas where thermal energy is so intense that it has torn atoms apart, stripping electrons from them and thus creating an ionized gas that is that is influenced by both electric and magnetic fields. Although there is an electromagnetic field that permeates through these locally charged ions and electrons, plasmas are mostly quasi-neutral, as is the plasma generated by the BMX lab. Plasmas make up the majority of the visible universe and are a subject of great interest and importance as we strive to better understand our world. Plasma, for the most part, exhibits chaos in its behavior—turbulence, in actual terms. The exact nature of such turmoil is yet to be discovered, and BMX seeks to observe plasma behavior when an obstruction is placed initsway. Thisobstruction,ofwhichtheeffectsareobserved,inthecaseofBMX,is specifically a magnetic obstruction induced by a current-carrying wire, as there is less direct observability of the kinetic turbulence of the plasma but more of a magnetic turbulence, the effects of which can be observed. The best case for plasma’s overwhelming importance in our lives can be seen by looking at our very own sun. The sun is a massive sphere of plasma that continuously ejects some of this plasma into the surrounding solar system, in a process known as the solar wind. Some planets, like Earth, have a magnetic field which interferes with the solar wind’s original path, forcing most of its particles to travel around the planet. Earth’s magnetosphere protects us from solar winds by altering the flow of its plasma. In our laboratory, we will utilize the BMX Plasma Gun to simulate the interaction between the solar wind and planetary magnetic fields. More specifically, in this experiment we will model this by placing a 1/8 inch diameter copper rod surrounded by ceramic downstream of the BMX Plasma Gun. By pulsing varying amounts of current through the rod, it allows it to act as a magnetic obstacle, so that we can study how the obstacle’s magnetic field interacts with the turbulent plasma. We predict a decrease in a measured magnetic field downstream of the magnetic obstacle and are in search of wave fluctuations within the plasma due to its interaction with the copper rod’s magnetic field.

Yiling Hou

Advisor: Xuemei Cheng

Micromagnetic simulations of field-driven antiferromagnetically coupled skyrmions pairs

Antiferromagnetically (AF) coupled skyrmions, characterized by antiparallel spin alignment between the skyrmion pairs, offer significant advantages for spintronic applications, including smaller skyrmions sizes, reduced skyrmions Hall effect, and increased data storage density. Our group has experimentally investigated the field-driven AF-coupled skyrmion pairs in [Co/Gd/Pt]₁₀ multilayers by photoemission electron microscopy (PEEM) imaging and further performed micromagnetic simulation with the vertical periodic boundary conditions. While the application of vertical periodic boundary conditions can increase the computation efficiency, its validity remains to be examined.

In this summer research, I will perform micromagnetic simulations of AF-coupled skyrmion pairs in [Co/Gd/Pt]₁₀multilayers using Mumax3 without vertical periodic boundary conditions. The 30-layer system will be modeled with parameters extracted from magnetometry measurements. The effect of the application of pulsed magnetic field with varied magnitudes and tilt angles will be simulated. The simulation results are expected to provide insights into the underlying mechanism of the field-driven skyrmion evolution revealed by the PEEM imaging.

Jessica Johnson

Advisor: Xuemei Cheng

Experimental study of sputtering yield and sputtering rate for thin film deposition

Thin films are layers of material with a thickness significantly smaller than their length and width, often possessing unique properties different from their bulk counterparts due to the finite size effect. They have wide applications in many fields, including nanotechnology and data storage. Sputtering, a commonly used physical deposition technique for growing thin films, is of great significance not only in research labs but also in industry. Sputtering yield, the number of atoms ejected per incident ion, is an important parameter for the sputtering process, and the sputtering rate is hypothesized to be proportional to it. However, the relationship between the sputtering yield and the sputtering rate has yet to be examined more carefully by experiments.

In this summer's research, I will collaborate with graduate students in the Cheng group to grow various metal films (Cr, Cu, Ti, and Au) by DC magnetron sputtering and SiO2 insulating films by RF sputtering. The thickness of the grown films will be characterized by measuring the small-angle X-ray reflectivity (XRR) of the samples. Furthermore, the sputtering rate and the sputtering yield of these sputtering deposition processes will be investigated. Our results are expected to clarify the relationship between the sputtering yield and the sputtering rate, providing guidance for the thin film sputtering process.

Sophie Lewis

Advisor: Michael Schulz

One-Dimensional Random-Field Ising Model

This project investigates the one-dimensional random-field Ising model of a magnet. The main goals of this project are to investigate how to compute and generalize the “on-spike” entropy at integer values of 2J/h as well as reproduce the result of “o􏰀-spike” entropy. The random-field Ising model consists of a lattice of spins, each of which can point up or down along the z-axis. At each site, there is a neighbor-neighbor interaction of strength J and an external magnetic field, h, (the sign of which is chosen randomly at each site). The energy of this system is lowest when each spin is aligned with the external magnetic field and when neighboring spins are aligned. However, at integer values of the ratio 2J/h, it is possible for chains of several spins to flip without changing the energy, resulting in a much greater entropy at these values (“on-spike” entropy) as compared to nearby values (“o􏰀- spike” entropy). Statistical mechanics, the Metropolis Monte Carlo method, and other mathematical techniques will be used to analyze this system. Magnets are imperative to contemporary society and understanding their empirical and theoretical properties can help in technological advancements.

Yingxiao (Thea) Liao

Advisor: Xuemei Cheng

X-ray Magnetic Circular Dichroism (XMCD) Study of Induced Pt Magnetic Moment in Co/Gd/Pt Multilayers

The magnetic proximity effect (MPE) describes the tendency for a heavy metal (HM) to be magnetized when placed near a magnetic material. This phenomenon of the induced magnetic moment of MPE has been intensively studied to understand the underlying fundamental physics and explore potential applications in spintronics. However, among the MPE-related studies, HM/ rare earth structures have been largely overlooked.

Our group has applied X-ray Magnetic Circular Dichroism (XMCD) to investigate the induced magnetic moment in HM Pt from rare earth element Gd in a specially designed [Co (0.5 nm)/Gd (1 nm)/Pt (1 nm)]₁₀ multilayers. XMCD spectra, the difference of X-ray Absorption Spectra (XAS) excited by left and right circularly polarized X-rays, can provide quantitative information on the atomic spin and orbital magnetic moments. Additionally, XMCD is an element-specific technique, powerful for studying the magnetic properties of materials at the atomic level.

In this summer’s research, I will analyze the XMCD spectra of [Co(0.5)/Gd(1)/Pt(1)]₁₀ multilayers measured at the Pt L_2,3 edges, Co L_2,3 edges, and Gd M_4,5 edges as a function of temperature. By applying the sum rules, the spin and orbit magnetic moments of Co, Gd, and Pt atoms will be calculated. These results are expected to shed light on the induced magnetism in Pt from rare earth elements, such as Gd.

Madeline Rehwinkel

Advisor: Michael Schulz

Equivalence of Instanton and WKB Methods in Quantum Mechanics

Quantum mechanics is applied in technology that we use everyday, including LED lights and smartphones. In quantum mechanics and quantum field theory, few systems can be solved explicitly via the Schrödinger equation. So, approximation methods are important. To calculate propagators, or probability amplitudes, across potential energy barriers, two approximation methods that are commonly used are the WKB approximation and instanton techniques (path integrals). Despite equivalent end results, the computations involved in both methods are so dissimilar that it is difficult to see at a technical level why both methods would agree. Two students in the 2021 SSR program sought insight from a simple, exactly soluble model, but I will take the complementary approach of proving the formal equivalence of both methods for any system. I will attempt to relate intermediate results from both methods to the Morette-Pauli-van Vleck functional determinant to formally prove that the propagators across a potential energy barrier calculated by the WKB and instanton methods are equivalent

Elinor Rivera

Advisor: Asja Radja

Flow Fields Created by Gorgonian Coral Polyp Tentacles

Coral reefs are integral to marine ecosystems, and rising ocean temperatures resulting from global warming are contributing to coral bleaching and disrupting these systems. Some Gorgonian corals, phylogenetic cousins to the more well-known hard corals, have been shown to be resilient to climate change, and although the mechanism by which they adapt to these changes isn’t definitively known, it is hypothesized that it may be related to their plastic morphologies and the way they interact with flow fields in their environments. This summer, I will be imaging the water flow through the tentacles of gorgonian coral polyps by building a tabletop flow tank and using particle image velocimetry (PIV). PIV is an optical measurement technique in which neutrally buoyant tracer particles are used to image the flow and velocity field of a moving fluid. Image recordings are converted to vector maps of the flow fields with a python-based open-access software to help us understand how water moves around gorgonians on the scale of individual polyps. This will, in turn, inform gorgonian polyp feeding abilities and give us clues to how they may combat warming ocean environments and survive.

Jordyn Strunk & Tina Zhao

Advisor: Michael Noel

Measuring ultracold Rydberg atom density using 2-body and 3-body dipole-dipole interactions

Determining the density of Rydberg atoms in a sample is crucial for advancing current studies and can contribute significantly to quantum computing and simulations. Rubidium-85 atoms in a magneto-optical trap can be excited into Rydberg states, which are energy levels with a high principal quantum number. We will measure and model 2-body and 3-body energy interactions to determine the density of Rydberg atom samples. This technique will be compared with other methods of measuring the density to corroborate the results.

Grace Trembath

Advisor: Asja Radja

Effects of simulated marine heat wave on polyp morphology in the gorgonian octocoral Eunicea flexuosa. 

As ocean temperatures rise due to anthropogenic-induced climate change, the health of coral reefs is put at risk. Corals rely on a complex microbiome to remain healthy, and extreme temperature fluctuations are detrimental to the delicate balance of organisms involved. Particularly, their ability to maintain homeostasis is threatened, as high temperatures lead to the breakdown of their photosystem, resulting in a condition called bleaching. Coral are host to a symbiotic algae called zooxanthellae, which share nutrients with the coral host. When a coral bleaches, it expels its zooxanthellae and is no longer able to photosynthesize. Longterm, the bleached coral colony is not able to obtain enough nutrients and is at risk of dying. One group of corals within the Subclass Octocorallia, gorgonians, have been shown to be resistant to bleaching. One hypothesis for this is that gorgonians are more adept at filter feeding, which allows them to compensate for a decrease in photosynthesis. In this study I will be measuring the tentacle length and body wall volume of the gorgonian Eunicea flexuosa during a simulated heat wave, to see if they may adjust the morphology of their polyps to increase their filter feeding capabilities in elevated temperatures.

Emma Barker

Advisor: Dustin Albert

Parental behavior predictors of adolescent resilience to stress in a cross-national sample of adolescents.Much of the research literature on the effects of early childhood experience on development has focused on links between early adversity exposure and later development of psychopathology. The target of much of this research is on the etiology of psychopathology. More recently, scholars have called for a shift in focus to identify aspects of early childhood experience that are associated with resilience in the face of stress exposure. There has also been a shift to examine the mechanisms behind childhood adversity and its developmental effects in order to more fully understand developmental processes. The current project will utilize data from the Parenting Across Cultures (PAC) study, a cross-national longitudinal study of adolescent development, to evaluate parenting behaviors that are associated with adolescent flourishing in the context of stress. More specifically we will examine associations between parenting behaviors (such as parental support for learning) and adolescent response to stressful experiences (such as the birth of a sibling). We will answer questions surrounding parental behaviors that act as protective factors for children who have experienced adversity. We will extend the research surrounding childhood adversity and adolescent resilience in the context of parental protective factors across cultures.

Priyanka Chandrasekar & Eva Yacura

Advisor: Ariana Orvell

The Role of Rituals on Helping Children Exert Self-Control

Young children are often  faced with situations in their daily lives where they are expected to show self-control and regulate their emotions. The common perception surrounding the exertion of self-control is that it is effortful. However, there’s growing evidence that it doesn’t have to be. Research shows that rituals—   predefined sets of actions that are carried out the same way each time —  may provide one less cognitively taxing way to promote self-control among adults, because they don’t require the enactor to consciously change their thought process and instead makes use of simple physical movements, unlike other tools for self-control such as reconstrual or mindfulness strategies (Hobson et al, 2018; Tian et al., 2018; Orvell, 2021). However, it’s unknown whether engaging in a ritual helps children enact self-control. To bridge this gap, we will explore how enacting a novel ritual affects children's perseverance at a task that requires self-control. In our study we use an experimental design where children, ages 6 to 9 years old, are randomly assigned to either a control condition, where they enact a set of random movements, or a ritual condition, where they are taught a simple and novel set of ritualized actions. Children in both conditions are encouraged to help the researcher with a boring computer task by locking as many pegs as they can onto a board with the option to take breaks at any point by playing a fun computer game, with a 15-minute time cap, mimicking everyday temptations in the real world. We will measure how long participants choose to work on the boring task, how many pegs they lock in the boring task, and how long participants play the fun game. Our hypothesis is that children assigned to the ritual condition will persist at the boring task for longer, and work more efficiently, than children in the control condition. This research may provide an easy and efficient way  for young children to persist longer at tasks that require self-control, such as completing homework.

References:

Hobson, N. M., Schroeder, J., Risen, J. L., Xygalatas, D., & Inzlicht, M. (2017). The Psychology of Rituals: An Integrative Review and Process-Based Framework. https://doi.org/10.31234/osf.io/98v3f

Orvell, A. (2021). Grant Proposal – Can rituals help children exert self-control?.

Tian, A. D., Schroeder, J., Häubl, G., Risen, J., Norton, M. I., & Gino, F. (2024). Enacting rituals to improve self-control. SSRN Electronic Journal. https://doi.org/10.2139/ssrn.4804271

Liujun (Cynthia) Chen

Advisor: Thomas Le

Gendered Racial Microaggressions and Asian American Women’s Body Appreciation: An Intersectional Investigation

Distorted and negative body image is a significant health problem among Asian American women. This issue stems not only from mainstream beauty standards, which typically idealize slender European American women, but also from more direct race-related oppression faced by Asian American women. Previous research has identified various cultural and racial factors linked to disordered eating in this group, such as racial discrimination, self-esteem, and internalized media messages (Cheng, 2014). However, few studies have used an intersectional approach to examine the connection between gendered racial microaggressions and body appreciation among Asian American women.  This research study thus explores the association between gendered racial microaggressions and body appreciation among Asian American women. In addition, the current study also examines whether internalized racism mediates this association and if resistance and empowerment against racism moderates it. 

In the current study, Asian American women will complete a cross-sectional online survey. Participants will respond to several questionnaires including the primary variables of the study, such as body appreciation, gendered racial microaggressions, and resistance and empowerment against racism. I hypothesize that there will be a negative association between gendered racial microaggressions towards Asian American women and their body appreciation. Moreover, I propose that the internalization of racism acts as a mediator in this association, while resistance and empowerment against racism serves as a moderator. 

This study will provide insights on potential interventions for addressing negative body image among Asian American women. Specifically, it will be helpful for therapists to integrate racial factors, such as internalized racism, into their treatment to address issues related to body image. Therapists can also work on improving self-esteem and developing self-worth among Asian American women clients who have negative body image. Therapists may also consider encouraging Asian American female clients to opt into social environments and relationships where their intersecting identities are affirmed instead of derogated. 

Grace Foresman

Advisor: Cora Mukerji

Associations among self-reported and performance-based measures of inhibitory control, and childhood adversity

Inhibitory control, commonly referred to as self-control, is defined as a person’s ability to curb or alter their own behavior especially to conform to internal or external expectations (Duckworth and Kern, 2011; Buchanan, 2016). Understanding and accurately measuring inhibitory control is important as previous research has found low levels of inhibitory control can predict lower quality of life especially regarding health and financial stability (Saunders et al., 2018). The most common types of assessments used to study inhibitory control are self-report questionnaires and performance-based tasks such as the Flanker or Stroop tasks (Snyder et a., 2021). Though the assessments purport to measure inhibitory control, recent literature has yielded conflicting findings about the strength of correlations between these two methods of assessing inhibitory control (Duckworth and Kern, 2011). Some previous researchers found relatively weak correlations between self-report and performance-based tasks, while other studies found a strong correlation between the two methods (Saunders et al., 2018; Wenerhold and Friese, 2020; Buchanan et al., 2010). Similarly, regarding adverse childhood experiences (ACEs), previous research suggests that self-report versus performance-based measures of inhibitory control yield different patterns of association with ACEs. Researchers found that self-report measures of inhibitory control sometimes showing significant associations with ACEs, while performance-based measures show more varied findings in significant association (Compton et al, 2024; Fava et al., 2023).

For this summer, I intend to investigate the potential associations between self-report and performance-based measures of inhibitory control and their relationship to experiences with early childhood adversity. I will research these inconsistencies by first seeing if the self-report questionnaire BRIEF-A inhibitory subscale scores correlate with performance on the performance-based Flanker task in young adults. Then I will test whether adverse childhood experiences (ACEs) correlate with Flanker task performance and/or the BRIEF-A inhibitory subscale scores. I hypothesize that, based on previous research, that the BRIEF-A inhibitory subscale scores will have a low correlation with Flanker task performance (Saunders et al., 2018). However, the BRIEF-A inhibitory subscale scores and Flanker task performance will both show significant associations with ACEs based on the research by Compton et al. (2024 ) and Fava et al. (2023). Through this research, I hope to illustrate how these specific measures of inhibitory control relate to one another, which can further inform the similarities and differences between self-report and performance-based measures, and understand the potential ways inhibitory control may be impacted by exposure to early adversity.

Sofia Hanson

Advisor: Cora Mukerji

Assessing the mediating role of perceived stress in the association between childhood unpredictability and depression in young adulthood

Adverse childhood experiences, commonly referred to as ACEs, have been shown to have a myriad of effects later in life, long after a person’s initial exposure to the experience. For example, ACEs have been associated with greater perceived stress, which refers to the ways in which an individual reacts to or experiences the stress in their life (Benham et al., 2024; Gissandaner et al., 2022). Furthermore, both ACEs and perceived stress have been associated with poor mental health outcomes, including anxiety and depression (Ross et al., 2016; Gillespie & Rao, 2021). Childhood unpredictability refers to instability or unreliability in a child’s life in domains such as parental behavior, physical environment, and sense of safety. Recent studies have found relationships between childhood unpredictability and perceived stress (Qi et al., 2024), as well as between perceived stress and depression (Mirón et al., 2019). I plan to test whether childhood unpredictability is associated with how young adults perceive their current stress and whether this, in turn, is associated with depression. To do this, I will use survey responses to the Questionnaire of Unpredictability in Childhood (QUIC), which assesses unpredictability across five different subscales including parental involvement and physical environment; the Perceived Stress Scale (PSS), which assesses people’s thoughts and feelings about their current stress; and the Patient Health Questionnaire (PHQ-9), which assesses symptoms of depression. I plan to analyze survey responses to determine whether perceived stress acts as a mediating factor forming an indirect pathway between childhood unpredictability and depression in young adulthood.

Tianyi Li

Advisor: Cora Mukerji

Do Positive Childhood Experiences Interact with Unpredictability in Childhood to Predict Cognitive Flexibility in Early Adulthood?

Cognitive flexibility (CF) is commonly defined as the ability to shift perspectives, thinking patterns, and strategies according to the context of a situation.  In this way, CF allows an individual to flexibly change behaviors to adapt to changing environmental contingencies (Diamond, 2013; Brown & Tait, 2014). Emerging studies suggest that experiencing unpredictable childhood environments may be linked to enhanced CF abilities (Fields et al., 2021; Mittal et al., 2015; Pope et al., 2019). According to the Life History (LH) model, unpredictability represents an important dimension of childhood adversity. Within this framework, unpredictability refers to random fluctuations in exposure to adverse situations across space and time, which is often characterized by changes in households that directly impact parents and/ or children (Ellis et al., 2009). Another line of research has shown that positive childhood experiences (PCEs) predict more favorable outcomes in adults (Narayan et al., 2018; Han et al., 2023). However, few studies have examined the effects of interactions between ACEs, such as unpredictability, and PCEs on people’s cognitive and behavioral outcomes in adulthood. Therefore, this study aims to investigate how PCEs interact with the exposure to unpredictability in childhood to predict CF in young adulthood. The PCEs will be measured by Predictability, Opportunity, and Safety Dimensions of Environmental Variability Questionnaire (POS-DEV) (Lopez et al., 2024), the unpredictability will be measured by Questionnaire of Unpredictability in Childhood (QUIC) (Glynn et al., 2019), and the CF will be measured using both a self-report survey, the Shift Subscale score of BRIEF-A (Roth et al., 2013), and a behavioral task, the modified Dimensional Change Card Sort (DCCS) (Zelazo, 2006). Because some studies have shown that the self-report and task-based measures may better be understood as two complementary but distinct windows on cognition (Snyder et al., 2021), we will also examine in this study whether patterns of associations between PCEs, childhood unpredictability, and CF will differ depending on how CF is measured. We hypothesize that the PCEs will interact with unpredictability to contribute to differences in CF in young adulthood. Moreover, we hypothesize that performance-based and self-report measures of CF will only be weakly correlated as in previous literature. This study will clarify the effects of both the adverse and benevolent childhood experiences on an important self-regulatory ability, which could inform prevention and intervention strategies to promote positive adult outcomes for people who have experienced a high level of instability in their childhoods.

Xiaoyin (Miracle) Liu

Advisor: Thomas Le

The Effect of Internalized Racism and Racial Collective Self-Esteem on Asian American Adults’ Disordered Eating: Psychological Distress as Mediator

Research emphasizes the importance of considering how sociocultural factors affect the disordered eating behaviors of Asian American adults. The present study will thus investigate how internalized racism and racial collective self-esteem are associated with disordered eating among Asian American adults, as well as the potential mediating role of psychological distress. Secondary analyses will be executed with a dataset containing a final sample of 796 Asian American adults who completed a cross-sectional survey that contained validated questionnaires that measured disordered eating, internalized racism, collective racial self-esteem, and psychological distress. Based on our hypotheses, regression analyses will examine if internalized racism might be positively associated with disordered eating, and whether collective racial self-esteem might be negatively associated with disordered eating among Asian American adults. Additionally, a mediation  analysis will also investigate if psychological distress might mediate the aforementioned associations. Regarding the implications of the present study, researchers and practitioners are encouraged to be cognizant about how Asian American adult clients’ experiences of internalized racism and psychological distress may affect their disordered eating. Pending study results, researchers and practitioners may also strive to increase racial collective self-esteem among this population. This study will help lay the foundation for future longitudinal research or research that examines these phenomena among specific Asian ethnic subgroups.

Sara Mayungo

Advisor: Thomas Le

Cultural and Gender Role Influences on Mental Health Outcomes in Queer Latina Individuals: Examining Sexual Empowerment and Disordered Eating

This research study seeks to unravel the intricate interplay of cultural, social, and clinical factors influencing the mental health and well-being of queer Latina individuals, with a focus on sexual empowerment and disordered eating. The study aims to explore the effects of Latinx cultural expectations and gender roles on mental health outcomes within this community. Using a survey methodology, a collection of validated scales will be employed to measure the independent variables, including Latinx cultural factors (Marianismo and Familismo), queer identity variables (open identification, community pride), and exposure to traditional gender roles. Mediators may include Religiosidad and sexual trauma. Mental health variables will serve as the study’s dependent variables, specifically sexual empowerment and agency as well as disordered eating.

I hypothesize that adherence to Latinx cultural factors (Marianismo and Familismo) and conflict with gender roles will impact mental health outcomes among queer Latina individuals. Specifically, higher adherence to cultural norms may be associated with increased rates of disordered eating and decreased sexual empowerment, with histories or sexual trauma/assault and Religiosidad acting as potential mediators. This research aims to provide crucial insights for mental health practitioners, guiding the development of culturally competent approaches. By understanding the complex interplay of cultural, social, and clinical factors, therapists can better support queer Latina individuals navigating their mental health, addressing generational trauma, and reconciling their identities within cultural contexts. Ultimately, this study contributes to fostering inclusivity and equity in mental health care for a diverse population.  

Sofia Vinci

Advisor: Cora Mukerji

Do positive experiences mitigate the effects of adverse childhood experiences on emotion regulation in adulthood? 

The effects of adverse childhood experiences (ACEs) on health outcomes have been widely studied in psychological research literature, including studies in the Philadelphia area exploring the effects of both family- and community-level exposures to adverse experiences like witnessing violence, suffering discrimination, or experiencing the effects of poverty. Research on ACEs shows that negative events experienced during childhood can have far-reaching effects on development, including the ability to emotionally regulate oneself and maintain relationships (Schultz and Waldinger, 2016; Kim and Cicchetti, 2009). Research also suggests that one’s emotional regulation ability has a strong relationship with mental health struggles such as depression and suicidal ideation (Garnefski et.al., 2001). However, there is much less research on the relationship between positive childhood experiences, such as having a supportive peer group or positive role model, on emotion regulation skills. To address this gap in the research, I will test whether positive experiences mitigate the effects of adverse childhood experiences on emotion regulation in adulthood. I will be using data from a retrospective study that asks participants to reflect on their adverse and positive childhood experiences and self-report on the cognitive emotional regulation strategies that they use in daily life. The Predictability, Opportunity, and Safety Dimensions Environmental Variability (POS-DEV) questionnaire will be used to measure positive childhood experiences, the Philadelphia Adverse Childhood Experiences (ACEs) questionnaire will be used to measure adverse childhood experiences, and the Cognitive Emotion Regulation Questionnaire (CERQ) will be used to measure adaptive and maladaptive cognitive coping styles (Lopez et al., in preparation; Glynn et al., 2019). I hypothesize that there will be a relationship between adverse childhood experiences and differences in the adaptive coping strategies they use as young adults; I further predict that this relationship will be moderated by positive childhood experiences, such that the effects of adverse experiences on coping styles will be buffered. This is a new area of research that may provide greater context, and perhaps hope, into mitigating strategies for those recovering from abuse, neglect, or other forms of adversity. 

Ziting Zhang & Betty Zuo

Advisor: Anjali Thapar

EEG Study of Virtual Reality and Memory Performance

Researchers have traditionally utilized 2D environments to assess memory performance. However, the increasing sophistication of virtual reality (VR) technology offers a novel approach for simulating real-world environments that replicate sensorial characteristics such as complex visual scenes and audible conversations (Corriveau Lecavalier et al., 2018). Previous research shows that while immersive environments can improve spatial presence and potentially enhance long-term memory, the quality of immersion varies by technological setup, leading to inconsistent memory recall among participants (Mania & Chalmers, 2001; Ventura et al., 2019). The goal of this study is to investigate the impact of different immersive environments (3-D VR, 2-D gaming) on memory performance. It also examines brain activity during this process using EEG. Participants aged from 18 to 25 years old will be recruited and randomly assigned into one of the three conditions: Static, 2-D Desktop, or VR to explore an apartment and assess the target objects. After exploring the apartment, participants’ memory for the target objects will be tested on the accuracy of identifying the correct objects and their confidence level of accuracy while wearing an EEG cap to record brain activity. We hypothesize that navigable VR environments will improve memory performance by creating a more immersive environment than traditional Static or 2D environments, which will be reflected in memory performance and brain activity measured by EEG. The result will provide valuable insights into the effects of the level of engagement in the external environment on cognitive performance and profound implications in curing memory-related disorders.

Judy Zhu

Advisor: Anjali Thapar

Working memory load and negativity bias in depression

This research focuses on the differential impact of increased cognitive load on negativity bias among individuals with varying depression statuses. Negative information tends to be preferentially encoded compared to positive information due to its high behavioral and evolutionary relevance. However, negativity bias can be mitigated when people allocate their cognitive resources to processing demanding focal tasks, rather than being an ever-present "attention grabber." This bias is even stronger among depressed individuals. Given the limited capacity of working memory, the impact of depression-specific working memory deficits on emotional processing remains unclear.

According to the inhibitory control impairments in MDD, an increase in working memory load will further decrease cognitive inhibition among depressed individuals, leading to heightened processing of emotional distractors and an increase in negativity bias. Alternatively, according to the resource allocation hypothesis, due to constant ruminative processing, depressed individuals have a more limited working memory capacity available for current tasks (Mondal et al., 2007; Austin et al., 1997). As a result, their emotional processing will be mostly influenced by mood-congruent vs. mood-incongruent emotional stimuli, and increased working memory load will have little impact on their emotional processing. The current research will examine the validity of different possible explanations for depression-related working memory deficits by directly comparing differences in negativity bias when processing emotional interference across different levels of cognitive load between depressed and non-depressed individuals (Van Dillen & Derks, 2012). Negativity bias is operationalized by the reaction time differences in gender judgment of emotional faces while performing the working memory task. Under low load, the reaction time is slower for negative faces, serving as a relative index of emotional interference on gender judgment. Observing changes in reaction time differences between gender judgment of negative and positive emotional faces will provide further evidence about specific cognitive impairments in sustaining negativity bias among depressed individuals. The findings of this research will provide insights into cognitive-emotional interactions in depression, contributing to a better understanding of the etiology of negativity bias and the ruminative cycle of depression.