Category: Undergraduate Research Scholars Program (URSP) – OSCAR

Understanding the Relationship Between Students’ Sense of Belonging in High School and College

Author(s): Dhruv Dewan

Mentor(s): Blake Silver, Sociology and Anthropology

My project is a focus on the relationship regarding sense of belonging as someone moves to College from High School. So in other words, what affects the sense of belonging in college students and what affects the sense of belonging in high school students and is there a correlation? I focused on this topic because there was some research on college sense of belonging, less research done on high school sense of belonging, and almost no research done on correlating this information. So I began with gathering information on each survey participant and moved on to asking them questions related to their sense of belonging in college, sense of belonging in high school, and asking them to compare their sense of belonging between these 2 time periods. Creating a collection of responses based on varying factors found in the demographic questions.

[Title]
Hello there, my name is Dhruv Dewan and this is a video regarding an OSCAR funded research project that I am currently in the process of concluding. A quick little introduction about me, I am a junior in the Honors college studying finance. So now that’s over let’s get into what the project is about.

[Next Slide]
My project is a focus on the relationship regarding sense of belonging as someone moves to College from High School. So in other words, what affects the sense of belonging in college students and what affects the sense of belonging in high school students and is there a correlation? I focused on this topic because I realized that I had a decrease in my sense of belonging as I came to college but other people had an increase. Trying to see if there was a correlation, I realized that there was some research on college sense of belonging, less research done on high school sense of belonging, and almost no research done on correlating this information. As such, I wanted to be the first one to do such research.

[Next Slide]
So I began with gathering information on each survey participant and moved on to asking them questions related to their sense of belonging in college, sense of belonging in high school, and asking them to compare their sense of belonging between these 2 time periods. Creating a collection of responses based on varying factors found in the demographic questions. Sadly because I am still concluding the survey, there is little to no analysis done at the moment.

[Next Slide]
Now, what can we do with this information? Hopefully later down the line this information can be transmitted into a test for High School students that will be able to inform students what college may be best for their sense of belonging. However, of course, this is if we can find a correlation and do a lot more research. I hope that this research can be done in multiple countries and we can compare if there is a difference among borders.

[Next Slide]
This research project couldn’t have been completed without some help. So thank you to Dr. Blake Silver, Dr. Karen T Lee, URSP, and finally OSCAR for funding this project. Thank you for listening!

Honors College Undergraduate Research Scholars Program (URSP) - OSCAR

Using image analysis to study the succession of coral reef micro-communities

Author(s): Teagan Corpening

Mentor(s): Jennifer Salerno, Environmental Science and Policy

Coral reefs are extremely important ecosystems that support a wide range of species and provide many ecological services. Many young corals react to cues from reef micro-communities that may alter where they choose to grow based on the presence and abundance of recruitment inhibitors and facilitators. Much research has been conducted on coral reef succession at the macroscale, but little research has been conducted on succession at the microscale. This research seeks to answer the question: do benthic micro-communities change over time, in light vs dark? To study this, settlement tiles were placed at three replicate sites on the White Hole coral reef site in Roatán, Honduras and left for one year to allow micro-communities to develop. Monthly images were taken of the top and bottom surfaces of tiles between June 2021 and September 2021. Morphospecies on each tile surface were identified and outlined by hand in ImageJ. Differences in community composition were calculated for each tile using Bray-Curtis distances and compared using permutational analysis of variance tests. There was no significant difference in community composition over time, but there were significantly different communities on the tops and bottoms of the tiles, likely driven by changes in the relative abundance of light. However, the data used in this project is a portion of the total data collected. Once more tile images are included in the analysis, it is expected that change in community composition over time will be significant. The implications of these results could help improve future restoration methods.

Title Slide:
Hello, my name is Teagan Corpening, and I will be presenting my research, “Using image analysis to study the succession of coral reef micro-communities”. This work was performed in the Salerno Lab.

Introduction:
Coral reefs are important ecosystems because of the many ecological services they provide, including coastal protection and providing habitat for a wide range of species. Protecting coral reef ecosystems is integral to protecting the biodiversity of marine ecosystems and preventing shoreline degradation. Understanding coral reefs at the microscale is important because of the connection between micro-communities of algae and other invertebrates that live on the sea floor and large-scale coral reef health. Coral recruitment and cover are heavily influenced by micro-communities. By better understanding the influences on coral recruitment, restoration methods can be improved.
I am working with Jordan Sims, who is a PhD student working on a larger settlement project in Roatan, Honduras.
My project seeks to better understand coral reef succession at the micro-scale by studying how micro-communities change through time and how environmental conditions, primarily light, drive community succession. My project seeks to answer the question: Do benthic micro-communities change over time, in light vs dark? This was done by observing community succession focusing on six different functional groups (CCA, fleshy macroalgae, filamentous algae, turf algae, other invertebrates, and biofilm). The presence of different functional groups is important to differentiate between because some groups, like turf algae, are coral recruitment inhibitors while other groups, like CCA, are coral recruitment facilitators.

Study Site:
This study was carried out in Roatan, an island off the coast of Honduras in Central Latin America. My study site is a reef on the northwestern coast of Roatan called White Hole.

Methods:
[1] Ceramic tiles were placed on three platforms across the White Hole reef site in Roatan Honduras. For this project, tile images at each platform were taken once per month between June and September of 2021. Images were taken of both the top and the bottom surfaces of each tile. The primary difference between the top and bottom surfaces of the tiles was the amount of light available to the communities. The tops of the tiles received more light than the bottoms of the tiles.
Here’s an image of one of our tile platforms once it has been secured to the reef. Settlement tiles were secured to the platform using zip ties.
[2] Here are representative unedited tile images after the tiles were removed from one of the platforms. On the left, we have the bottom of the tile and on the right, we have the top of the same tile.
[3] I cropped the unedited images to remove the unnecessary pieces including the collection bag and the sides of the tiles.
[4] These are the labelled tile images. I performed labeling by hand in ImageJ. I identified 85 different morphospecies and traced the boundaries of each morphospecies. The morphospecies were then combined into 6 different functional groups. After labeling, I used ImageJ to calculate the relative abundance of each functional group in each image.
functional groups:
These are examples of the six different functional groups that I combined the morphospecies into. These groups include Crustose Coraline Algae, filamentous algae, fleshy macroalgae, turf algae, biofilm, and other invertebrates.

Results:
[1] Differences in community composition over time and between tile surfaces were calculated using Bray-Curtis distances. To compare the micro-community composition on the tops and bottoms of the tiles and the micro-community composition through time, PERMANOVA tests with 999 permutations were performed. There was no significant change in community composition over time, but there were significantly different communities on the tops and bottoms of the tiles.
[2] On this graph, we can better visualize the drivers of the differences in functional group composition between tops and bottoms of the tiles. Bottom surfaces had a significantly higher percent cover of biofilm than top surfaces. We can also see a higher percent cover of other invertebrates on bottom surfaces. However, top surfaces had higher percent cover of turf algae and fleshy macroalgae.

Discussion:
The tops and the bottoms of the tiles were determined to have different community composition. This is most likely because of the differences in light. These results are supported by other studies that have also seen changes in benthic cover and functional group productivity influenced by the abundance of light (Vooren, 1981). The greater amount of light available to the communities on top surfaces is likely what is driving the observed increase in algal growth.
This study only used a portion of the tile images and data that were collected in the larger settlement project. There are four additional timepoints from this reef site and another full set of images from a replicate reef site. For the next steps of this project, I’ll continue to analyze more tile images so that more timepoints and replicates can be included in statistical analysis in the future. We expect to see a significant pattern of change emerge as more tile images are included in the project’s scope.
Acknowledgements:
Thank you to Dr. Salerno for being my mentor, to Jordan for helping me with the analyses, and to Jennifer Keck for taking the tile photos.

Honors College Undergraduate Research Scholars Program (URSP) - OSCAR

First-Generation College Students and their Housing Status on College Belonging

Author(s): Joselyn Castellon Almanza

Mentor(s): Blake Silver, Honors College

Our population is becoming more diverse with each generation. With many financial and housing options, this has resulted in a big portion of the college student population being first-generation students yearly. This is representative in the literature, especially regarding first-generation identity and housing status. First-generation students struggle with a lack of information and unknown expectations as they face higher education with no reference point. Added to the first-year experience, it could result in a challenging and confusing year. Housing status as a topic has been explored as learning communities, residential dorms, and commuting from home. These living spaces provide different resources that could aid the college experience. Studies have investigated its impact on academic success and retention, but not college belonging. College belonging is about a sense of security, and its investigation has been seen to support academic success. Thus, focusing on this topic could bring about ways to increase the quality of the college experience. As a result of past literature, this study will explore the impact of first-generation and housing status on college belonging with first-year students. I will explore the connotations and feelings behind the statuses of “first-generation” and housing, with specifics to the terms “commuter” and “resident.” I will then see if it may influence a student’s sense of self and how they think others may view them, thus affecting their sense of belonging. My investigation is based on hourly in-person interviews with first-year students that fit those identities. Through this, I will explore the relationship between first-generation and housing status on college belonging. I hope to provide more support for students’ overall success and well-being in college with my anticipated findings.

Hello, I am Joselyn Castellon Almanza, and my mentor is Dr. Blake Silver. And this is my project on first-generation college students and their housing status on college belonging.

I then investigated housing status cause housing status as a topic has been explored as learning communities, residential dorms, and commuting from home. These living spaces provide different resources that could aid the college experience. One study looked into housing status on academic performance. It saw that commuters earned a higher academic standing than residential students (Simpson and Burnett, 2019). This was interesting because a lot of past studies stated the opposite. It even went further to say that students’ academic status is based on how much they invest their energy into the college experience instead of the actual living situation (Simpson and Burnett, 297). And since studies have investigated its impact on academic success and retention, it led to me thinking of housing status and how it could impact college belonging.

College belonging is about a sense of security, and its investigation has been seen to support academic success. Thus, focusing on this topic could bring about ways to increase the quality of the college experience. A study has seen that college belonging matters as it works with well-being, high persistence, and graduation. This discussion of belonging can help us see its importance, its complexity, and how it provides a feeling of security (Nunn, 48). Another study has shown that socioeconomic status informs how students experience belonging (Ostrove and Long 2007).

This leads to my research questions; What impact does being a “first-generation college student” have on someone? What impact does housing status, commuting or residential, have on someone? How do these identities influence college belonging?

With these questions, I will explore the connotations and feelings behind the statuses of “first-generation” and housing, with specifics to the terms “commuter” and “resident.” I will then see if it may influence a student’s sense of self and how they think others may view them, thus affecting their sense of belonging.

My investigation is based on hourly in-person interviews with first-year students that fit those identities. There will be 16 interviews with 16 people. Eight will particularly fit under the commuting identity, and eight will fall under the residential identity. With all being under the first-generation college student identity. The interviews will then be coded with Dedoose coding software. It will look at what words or phrases are used frequently. I will then analyze it to see the reoccurring theme and draw conclusions from it.

My interview questions are based on three topics: first-generation identity, housing status, and college belonging. And here are some of my example questions. For example: “What comes to mind when you think of a first-generation student?”, “How do you think others view you based on your housing status?” and “Do you feel like you belong in your college based on your definition?”

Through this, how the first-generation experience and housing status affect college belonging will be further investigated. In the future, I hope it leads to more efficient resources for first-generation college students and college housing. As well as reform programs to help those students that fit those identities.

Thank you. If you have any questions, please contact me at [email protected].

College of Humanities and Social Science Undergraduate Research Scholars Program (URSP) - OSCAR

An Analysis of Eastern Box Turtles (Terrapene carolina carolina) on Age, Sex and Habitat Population Sizes

Author(s): Jordan Davis

Mentor(s): Travis Gallo, Environmental Science and Policy

The Eastern Box Turtle (terrapene carolina carolina) is a rapidly declining species in many urban areas of North America. However, there are less research on rural box turtle populations. In this project, an analysis on turtle populations of habitat type, age and sex were discovered. After six weeks of fieldwork research, 105 turtles were discovered on 408 acres of The Clifton Institute’s property. Out of 105 turtles, five turtles had radio transmitters to discover the average home range of the turtles. To gather analysis, radio telemetry was used for the radio-tracked turtles, and the surveyed turtles were observed through a marked-recapture technique. Once discovering the average home range of the turtles on QGIS, the turtles on average do not move far distances, as the property has adequate vegetation, shade, and water on the preserve. Although, the females traveled farther than males in this experiment. During analysis, the Schumacher-Eschmeyer method was used to determine population estimates. There are an estimated 435 turtles on site, with 203 projected males and 245 projected females. This research contradicts many studies focusing on urbanized turtle populations, with the premier cause of turtle mortality stemming from females making vehicular contacts on roads. In addition, the most precise populated habitat was the mature forest over the wetlands. The discovery contradicted the original hypothesis that turtles preferred to live closer to water than the forest.

College of Engineering and Computing Honors College Undergraduate Research Scholars Program (URSP) - OSCAR

Analyzing how the EEG of a person changes when playing a rhythm game of a familiar and unfamiliar song in a VR environment

Author(s): Xander Boit

Mentor(s): Nathalia Peixoto, Neuroscience Program

Familiarity in music has been reported as an important factor in creating emotional and positive responses in the brain. Previous research indicates that the brain is interpreting familiar music completely differently than how it interprets unfamiliar music. To our knowledge, there is no EEG dataset correlating completion of a physical task during exposure to music. Our project aims to fill this gap by acquiring EEG data that would show the impact of unfamiliar and familiar music on a person’s brain after completing a rhythm game in a virtual reality environment. We will use a five-electrode, commercially available headband to acquire EEG data during experiments with healthy subjects. We then compare unfamiliar and familiar music before and after playing the rhythm game, “Beat Saber”. The experiment will follow a matched pair design, meaning that each individual subject will only be compared to their own EEG. The virtual reality videogame, “Beat Saber”, is a rhythm game that involves using imaginary sabers in order to slash boxes that indicate a specific direction along with the song playing during the game. Using MATLAB, the sets of EEG data will be separated into the brain wave dominant frequency bands (beta, alpha, theta, delta, and gamma). Finally, the power of each band will be compared to its counterpart to investigate patterns across all trials. Using previous literature findings, conclusions will be determined to see if there are any significant differences between the generated data set and existing data.

I am Xander Boit and my project is Analyzing how the EEG of a person changes when playing a rhythm game of a familiar and unfamiliar song in a VR environment

My mentor is Dr. Peixoto and my department is bioengineering.

This was completed in Fall 2022 as a URSP. Thank you OSCAR for providing funding and support for this project.

So existing literature; familiarity in music has just generally a positive correlation with how the brain responds.

There are a couple of sources I used.

The first one says that familiarity in music has been reported as an important factor in creating emotional and positive responses in the brain.

And then the second source says additionally, music can improve cognitive performance, especially when it is familiar.

And so, essentially what I concluded from all of these and other sources I found is that previous research shows that there are clear benefits associated with familiar music in relation to mental state.

Now what I was looking for is how does this actually apply to an action. Because a lot of this research is kind of stationary or is just a task. But with the VR equipment, we have this opportunity to have them record the EEG data while they are actually doing a task that involves full-body movement and music at the same time.

And so that’s why I kinda chose to do this project.

So the technology that I have for this project is in three categories: Virtual Reality Equipment, EEG Recording Equipment, and the Data Analyst Software.

The first part is the virtual reality equipment. The lab I am in has the HTC VIVE Pro 2 Headset.

These two pictures you can see are pictures I took in the lab of the VR headset. The top picture being the actual headset and the bottom being the two hand-held controllers that you use when using the headset.

I had a decent amount of issues getting the VR headset to work properly throughout the semester, and it kinda delayed my project a decent amount.

The first one was I had issues with audio output. The headset actually has two speakers on it, you can see off to the side of the top picture. The speakers are tilted outward currently. They would not play audio. And if they did play audio, if I got it to work, they were super scratchy and basically unbearable. Obviously, this is a huge issue for an audio based project, so I spent about several weeks figuring this out and eventually I just figured out that unplugging the cords and replugging them back in until it works is actually consistent for some reason, and I haven’t had many issues with it since, which surprises me to be honest. But, if it works, it works.

Then the other issue, probably the bigger issue, if video resolution. Now, we have a pretty good graphics card in the computer that is attached to this VR headset. But this VR headset is so powerful that it can outperform the top-of-the-line graphics cards. I decided to use my whole budget in one go and buy a new computer, which has a 3060 graphics card and top-of-the-line for lots of stuff. It was a pretty good deal since graphics cards are cheaper right now. I bought that, but with the whole new computer, it got delayed three to four times due to miscommunication, product delays, and whatnot. I will be getting it in the middle of December. I currently do not have it to actually use for this project, but I will have it for next semester.

The video game I am using is Beat Saber, which is probably the most popular VR game. If you have seen any VR game, it’s probably been Beat Saber. It’s essentially Guitar Hero, but VR. You have the two controllers and you have to slash things.

I have a video actually, it’s about thirty seconds long. I can show a little bit of what it looks like. This may be a little loud. I recorded this in the lab. You can see the two sabers I am holding. My left hand is the red one and my right hand is the blue one. You can see I am just slashing with the arrows on the cubes with the beat of the music. So this is how we are making it into a rhythm game recording thing.

I think the really cool thing about this is the EEG part of the project. We have the Muse 2 Headband in the lab, and that is what I am using; there is a picture of it to the right there.

This Muse headband records at four different locations: left ear, left forehead, right forehead, and right ear. So basically it’s just around the outside of the skull.

The cool thing about this is that when I initially designed the project, we planned on having a full-cap EEG on, which meant that we couldn’t use it during the VR section. But with this one, you can actually wear this underneath the VR headset. So we can record the EEG and have the VR going at the same time, so we don’t have to worry about any gap in time or just any of that error that could occur. This is very useful for getting what is actually going on in the brain while the activity is happening.

The third part of the technology aspect is MATLAB. You probably have heard about it before if you know anything about programming. It’s essentially a software that allows me to filter and analyze EEG data.

I went into it with two main goals. To separate my data into key frequency bands, like delta, gamma, beta, alpha, and theta. These are different frequency bands. Essentially, there is known information about what these bands indicate: calm, stressed, active. Just a bunch of different things, but I am not going to go into all of them, since they are kinda specific in some categories.

We eventually want to use these key frequencies to compare power levels of each band against familiar and unfamiliar samples, because this is a matched-pair design. Meaning that for each person, we are getting a familiar and unfamiliar sample. We are going to link those two samples together and look at the difference essentially of these power levels of each of the five frequency bands.

The progress so far; we haven’t made all the progress yet since I have not collected data yet. Generally, I think I got behind in this project, which is my own fault. I have the data, its loaded into MATLAB, and I can separate the frequency bands. I just need to figure out how to filter it exactly, which takes a decent amount of time going through literature and seeing what previous researchers have done. So that is where I am currently at with MATLAB.

Here is a picture I generated using my MATLAB code. This shows the RAW EEG data of the four locations that I talked about previously. The left ear, left forehead, right forehead, and right ear. You can see it’s a mess, this is why we need to filter and separate them. Because right now, this doesn’t mean anything.

This is an example kinda thing. This isn’t exactly how I want my data to look, since it is filtered incorrectly for what I am trying to do. You can see this separates the data into the five frequency bands. You can see the levels and how this is. This is kind of what I want, then we are gonna take the power level of these and compare them against each other for the familiar and unfamiliar.

For research logistics. The IRB approval process; I started way too late. I got distracted with troubleshooting the VR equipment and didn’t realize how long it would take. Right now I am at the final stage of approval for the IRB, so hopefully I get that done and can start next semester as soon as possible.

I mentioned it before, but computer purchasing delays. Had a lot of miscommunications, and it’s been pushed back to the middle of December now, when it is going to arrive.

Future plans. Get IRB approval, which I just mentioned. Gather the data, after I have the approval from IRB. Analyze and report the findings. And depending on how the results turn out, publish a research paper on the results.

This is my work cited. Thank you so much for watching this video and let me know if you have any questions.

Undergraduate Research Scholars Program (URSP) - OSCAR

Assessing the methods to determine the black hole mass in type II (obscured) active galactic nuclei

Author(s): Antonio Alt

Mentor(s): Mario Gliozzi, Physics and Astronomy

According to General Relativity, all the information about a black hole can be derived from just the mass and its angular momentum (charge as well but we assume it is electrically neutral). It is therefore important to have accurate measurements of the black hole mass. In this research project we investigated the masses of black holes within Type II (i.e., obscured) Active Galactic Nuclei (AGN) calculated using the M- σ relation, a correlation between the black hole mass and the galaxy bulge frequently used when direct dynamical methods are not available. We started from a sample of AGN selected from the hard X-ray sky survey done by the Neil Gehrels Swift Observatory, restricting it to X-ray sources with luminosity greater than 10^(42) erg/s and within 40 Mpc. These filters brought our sources down to 20 AGN. From the literature, we collected the black hole mass values obtained with dynamical methods (Maser, Virial Theorem, Stellar/Gas Dynamics) and compared them to the values measured using the M- σ relation. Our preliminary results suggest a substantial discrepancy between the black hole mass values measured with M- σ and the ones inferred with more direct measurements, indicating that the use of the M- σ relation for Type II AGN may be problematic and must be treated with caution.

0:01
hello my name is Antonio alt and the
0:03
research project I’m presenting today is
0:05
assessing the methods to determine the
0:07
black hole mass and type 2 obscured
0:10
active Galactic nuclei
0:12
this project was conducted under
0:13
supervision of Dr Mario gliosi
0:19
what exactly is an AGN simply put active
0:22
Galactic nuclei are the centers of
0:24
galaxies whose Luminosity is powered by
0:26
black hole accretion
0:28
of course other traits we have seen are
0:31
Broadband continuums from infrared all
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the way up to in some extreme cases
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gamma rays strong emission lines and a
0:37
high amplitude variability
0:40
currently AGM gets put under the unified
0:43
model which has two categories type one
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unobscured where the Broadline region
0:48
and accretion disk are visible
0:51
and type 2 where they are blocked off
0:57
by the obscuring Taurus
1:00
the nice thing about when you have a
1:02
type one is that you can do direct
1:04
observations to find the mass of the
1:06
black hole through capillarium mechanics
1:09
and other things such as that
1:12
what are we trying to do is just that
1:14
general relativity states that all we
1:16
need to know about a black hole is just
1:17
the mass angular momentum in charge
1:20
and of course the methods for obtaining
1:23
the mass so black will go into direct
1:24
and indirect methods
1:27
when we can see everything we will
1:29
typically try and use a direct method um
1:32
because those are the most accurate but
1:33
they do take a lot of time
1:36
so
1:39
um with an indirect method it just uses
1:41
mathematics and physics to
1:43
derive a mass through other means when
1:46
we can’t use a telescope or
1:50
um any type of direct observations
1:53
some dark methods don’t work for type 2
1:56
such as
1:57
reverberation mapping
2:00
um and
2:02
um
2:03
any type of stellar and gas Dynamics in
2:05
the optical Spectrum
2:07
so indirect methods become way more
2:09
important because we have to use them in
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a lot of cases
2:14
so M Sigma is the most common one that
2:18
is used for obscured AGN
2:21
and all it does is it has a correlation
2:24
between the mass of the black hole and
2:26
the velocity of this version of the
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Stars around the core of the Galaxy
2:31
for the methodology of this project we
2:34
use the data provided by the Neil
2:36
Garrell Swift Observatory and we
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filtered it by a max distance of 40
2:40
megaparsecs to make sure we had AGN and
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the immediate universe and a minimum
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Luminosity of 10 to the 42 herbs per
2:47
second
2:48
we look through the published literature
2:50
to get dynamical measurements and then
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we compared these measurements to the
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values taken by indirect methods such as
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M Sigma and x-ray scaling
2:58
x-ray scaling is just using the photon
3:01
index as an indicator for the black hole
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secretion rate which then can give us
3:06
the mass
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as for our preliminary results as we can
3:11
see things are not voting well for M
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Sigma where it is overestimating the
3:16
masses outside of our
3:18
um
3:19
uh fit for a correlation
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of course for our x-ray scaling method
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it is all fitting right within the
3:28
bounds as it should
3:31
um of course this could change if we do
3:33
further studies and find
3:35
um
3:36
more masses using x-ray scaling but as
3:39
of right now it is fitting perfectly
3:41
within our bounds
3:43
and to look in a logarithmic scatter
3:45
plot of these measurements we can see
3:49
that 8 out of 10 of our
3:52
um
3:53
M Sigma mass of AGN
3:55
masses are
3:57
outside of our bounds for correlation
4:01
meanwhile for our x-rays uh scaling AGN
4:06
masses 5 out of five are right within
4:09
the range as expected from our
4:12
histograms
4:14
so as for the implications our
4:16
preliminary results show a discrepancy
4:18
between the black hole mass measured
4:20
with M Sigma compared to direct
4:22
measurements which we do know are
4:24
accurate this tells us that the use of M
4:26
Sigma for type 2 AGN may be problematic
4:29
and we have to proceed with caution if
4:31
we decide to use it in the future
4:33
these are our references
4:37
and that’s for our acknowledgments we
4:39
would like to thank ursp at George Mason
4:41
University for funding the study and
4:43
James Williams for providing us with
4:45
guidance and for converting the data in
4:47
the papers into usable files
4:49
thank you

College of Humanities and Social Science Undergraduate Research Scholars Program (URSP) - OSCAR

Barriers to EAP Utilization: A Behavioral Economic Perspective

Author(s): Aparna Mathew

Mentor(s): Lauren Kuykendall, Psychology

With the onset of the COVID-19 pandemic, work-related stress has become a prevalent topic of discussion in North America, with estimates suggesting that over 50% of North Americans in the labor force experience stress daily. With high work stress remaining a relevant issue in the workplace, organizations have made efforts to combat the significant levels through the increasing availability of the employee assistance program (EAP). Despite availability and studies on its benefits for both employees and employers, the EAP remains underused by employees for various reasons. Although previous research has studied the structural and demographic barriers to EAP utilization, there is a lack of diverse findings on the individual differences that hinder EAP usage. This project suggests that behavioral economics can be used to assess the dispositional barriers to EAP usage; specifically, this paper suggests that individuals who steeply discount the value of future goods and services will be less likely to utilize the EAP. This project will adopt a measure of temporal discounting to assess individual discounting values and study these values against a measure of EAP usage propensity. As the previous literature on dispositional barriers remains fixed on individual trust and EAP usage, this paper will also adopt measures of trust in confidentiality and efficacy to assess whether or not time discounting can explain the dispositional variance in under-utilization above and beyond the known predictors. It is expected that individuals with high discount rates will be less likely to report willingness to utilize the EAP.

Hello my name is Aparna Mathew and I am working with Dr. Lauren Kuyekendall to complete a psychology and economics project on barriers to EAP utilization in the United States. More specifically, I’ll be taking a Behavioral Economic Perspective to study these.

To get started on some key topics, the EAP stands for employee assistance programs. These are free of charge counseling services that address a lot of the things that private market therapy would address; things like stress, personal issues, and anxiety. Research suggests that the majority of full-time US employees will have access to the EAP in 2021 and there’s been a ton of research on associations between EAP usage and increased positive predictor outcome variables like productivity and functioning that increased as the outcome variables as a result of the predictor variable which is the EAP usage, as well as job and life satisfaction.

So even though there’s all this research on the benefits of EAPs and the growing availability, we do know that the EAP is relatively underutilized and there’s been a lot of research on why that is. So there’s been some demographic research, which is generally more mixed in the results, but some have found that minorities tend to be over represented. Gender minorities like women in the workplace or racial minorities like black individuals. A little bit less mixed is the structural research, so things about the specific workplace things like managerial support, awareness and promotion. We find that typically if you promote your EAP services, you show support and people are more likely to use it.

There has also been limited research on the dispositional barriers, so things about the individual personality that might affect people’s likelihood to use the EAP. The research really focuses on these dynamics of trust. The people who trust the EAP, trust their efficacy, trust that they’re completely confidential, those are the same people that are more likely to use the EAP in the future.

While we were digging through the literature, what we found is there’s a general lack of viable information on the other dispositional characteristics, so at the personality level what could be influencing decisions to invest in one’s mental health through the EAP when they know they could benefit from it?

So, to study these questions we are looking at a temporal discounting or time discounting model. This is a behavioral economics model, essentially there’s a phenomenon that individuals tend to discount the future utility of goods and services. So, the longer you have to wait for a reward, the longer you have to wait to see the benefits of a decision, there’s a general trend where the subjective value of that reward actually decreases overtime.

So what we actually hypothesize is that we know that the EAP is underutilized, we know about the demographic situations, we know a lot of situational barriers, but we really don’t know much else about the individual that will predict EAP usage. Knowing that research indicates people tend to delay mental health help-seeking and health treatment, something like 10 years between the onset of a condition an actual treatment. We also know that there’s a behavioral economics concept is kind of explains why people might put off things with longer-term benefit may be people who steeply discount the future and more quickly discount the value of future goods and services are the same people that don’t really want to put time into the preventative help or find themselves not doing that.

So what we actually hypothesize is exactly that: people with steep discounting rates, which means the value of a good/service is steeply declining for them, are the same people who are going to be less likely to want to use the EAP. So to study this we are submitting a survey via Prolific, getting full-time US employees to answer questions. They’re going to be briefed on the EAP — what it is, what kind of things it covers — and I’m gonna ask them the likelihood of usage. What’s the possibility that they might use in the future? I am also going to measure trust in confidentiality and trust in efficacy to improve the incremental validity of our study because this is the most commonly cited dispositional barrier. Of course will be allowing them to play a game to allow us to sort of identify their temporal discounting task and rate and after that we are planning to obviously analyze our data will be using a hierarchical regression model to see if the variance in willingness to utilize the EAP can be explained by the previous predictors in the literature and our new predictors and would like to see some associations form there

Thank you for listening, that is my project and I hope you enjoyed it!

Honors College Undergraduate Research Scholars Program (URSP) - OSCAR

Comparing Growth Rates of Somaliland and Namibian Cheetah Cubs

Author(s): Gwendolyne Fields

Mentor(s): David Luther, Environmental Science and Policy

Cheetahs (Acinonyx jubatus) are classified as endangered species by the IUCN, facing major threats of habitat loss, illegal pet trade and human-cheetah conflicts. With approximately 7,500 individuals left in the wild across Africa, research is significant to understanding and ensuring their species’ survival. At Cheetah Conservation Fund (CCF), located in Namibia, research has been ongoing since its establishment in 1990, and was once known as the cheetah capital of the world. CCF also has a campus in Somaliland, where currently 86 cheetahs of the “Tanzanian cheetahs” (Acinonyx jubatus raineyi) are being cared for, and 29 “South African cheetahs” (Acinonyx jubatus jubatus) at Namibia’s facility. This project investigates the comparison of growth rates between Somaliland and Namibian cheetah cubs. Through CCF’s data of cheetah cubs rescued between 2006-2022 within Somaliland and Namibia, weights, meat and milk consumption has been recorded from 0-6 months and organized in a new Excel Spreadsheet. 19 individuals are recorded from Namibia, and 46 are recorded from Somaliland. Few statistics through RStudio have been done, however significant results of the sum of weights from 0-6 months with other covariates indicate males have a higher growth rate than females, and Somaliland has a lower growth rate than Namibian cheetah cubs. Further statistics will be conducted to understand more about growth rates and what affects it, as well as the difference between Namibian and Somaliland cheetah cubs.

Good Afternoon! My name is Gwendolyne Fields, and you are joining me here today with Peter, Tiger-lily and Senay in Namibia. For the past two months I have been here at Cheetah conservation fund, also known as CCF. CCF was established in 1990 by Dr. Laurie Marker, where the goal is to help conserve these endangered species.

So, a lot of our cats here are permanent residents. So, this means that a lot of them have come in before the age of 6 months and because of that, their mothers were not able to teach them the proper skills to actually survive in the wild. So, some skills including what prey to hunt, such as duikers, steenboks, springboks, kudus and oryx’s as well as what predators to avoid: lions, snakes and hyenas. And so, a lot of them have actually also been useful for research and understanding more about the species themselves and how to conserve them the best.

So here on our Namibian campus, we have 29 cheetahs and on Somaliland’s facility we have 86 cheetahs. So a lot of these cheetahs have come in at very different ages, so these siblings came to us at the age of four weeks. Others have come in at 5 days, 10 days, so very young. A lot of the cheetahs that have come in were rescued with different scenarios, so some farmers actually might have killed the mothers, some farmers might have captured them and in other cases people have kept the cheetahs as pets as well. So, like I mentioned before, having them here has been very useful for research and also their conservation.

Here are three of our cheetah cubs at CCF who arrived when they were 3 weeks old. Speaking of cheetah cubs for my research project, I have been working with Dr. Laurie marker, and other CCF staff members as well as my mentor Dr. David Luther where I am investigating the comparison of Somaliland and Namibian cheetah cubs growth rates. From data collected back from 2006 until most recently 2022, I have been gathering all this information on a new excel spreadsheet from individuals between the ages 0-6 months.

Other than spending time on my research project, I have been part of the cheetah team working to take care of the cheetahs by feeding them, giving their meds if needed, cleaning and managing their enclosures.

Moving on to the results for the project so far. I have created some graphs as well as produced some statistical analysis of the data through RStudio.

This first graph demonstrates the average weights of Somaliland and Namibian Cheetah cubs from the age of Day 1-14. As you can see there is a linear relationship between the weights and days of the cubs. The R-squared value is around 0.59 indicating a moderate goodness of fit of the model. We notice the Somaliland average weights are less than the Namibian weights. The second graph demonstrates the average weights of Somaliland and Namibian Cheetah cubs from the ages of Week 3-26. The R-squared value of 0.91 demonstrates a very strong linear relationship. Once again, the Namibian weights are larger than the Somaliland weights on average.

The third graph is a boxplot displaying the first two weeks of age. We notice the Namibian data appears to have more range and a higher average weight. The last graph is a boxplot displaying weeks 3-26 of age. We notice the Namibian data appears again to have more range and a higher average weight; however, it appears less robust than the previous graph. Running these last two graphs’ data through R, we found no significance in terms of their weights and comparing them between the two locations. Meaning the p-value was greater than 0.05.

Last but not least, the sum of the weights for all weeks did not appear to have significance with meat and milk consumption, yet the location of Somaliland was significant indicating their cubs are less likely to survive, and the males in general appear to have higher growth rates than females (indicating greater chance of survival).

We still have many questions to answer, such as how much the cheetah cubs grow in general, what month they grow the most and how exactly does diet affect their growth, especially relating between the two locations of cheetahs.

Thank you so much for watching and for everyone who has helped me on my project so far! Bye!

College of Humanities and Social Science Honors College Undergraduate Research Scholars Program (URSP) - OSCAR

Developing the cooperative sector of Northern Virginia: Worker-owner Experiences of Institutional Support

Author(s): James Condo

Mentor(s): Ben Manski, Sociology and Anthropology

Cooperative enterprises have long existed as a sustainable and democratic alternative to traditional shareholder-owned firms. Some of the major problems cooperative enterprises face include issues related to longevity, access to capital, and wages for employee-owners. With these problems, it is important to look to the nascent cooperative sector in the Northern Virginia Region, which has a growing number of firms. Understanding the influence of local and national institutions on the success of cooperative firms can be done in part through gathering insight into worker-owner experiences of institutional support. This project uses in-depth, semi-structured interviews to analyze the experiences of firm members with the institutions. The project is ongoing, but there are some initial insights given regarding improvements in local institutions.

Hi everyone, my name is James condo. My project is on the relationship between cooperatives and supportive institutions in local areas. The full title of the project is quote, developing the cooperative sector of Northern Virginia worker owner experiences of institutional support and, and was completed with the support of Dr. Ben Mansky from the Department of Sociology and Anthropology at George Mason University. This project is a part of the Undergraduate Research Scholars Program. It’s sponsored by Oscar at George Mason University. And here I am seeking to explore the relationship between the health of the cooperative sector and local supportive institutions. It is important to begin by giving some background information on this project and its significance as part of an ongoing community engaged research effort by George Mason University as an intern for the democratizing Northern Virginia project of the Center for Social Science Research at JMU. One of my main categories for research and database collection was that of worker and consumer cooperatives, which are enterprises that are owned by employees or by customers or members. These enterprises are part of an emerging sector in Northern Virginia that exists alongside more traditional shareholder earned owned firms. Prior to exploring the state of the cooperative sector in Northern Virginia, it is important to review some of the existing literature surrounding cooperative firms and the problems that these firms face. Part of my reasoning behind looking toward the relationship between local institutional actors and cooperative firms is due to the understanding present in much of the literature of anger institutions, which are either municipal organizations or nonprofits which are large, consistent supporters and customers of a cooperative firm. This model of an anchor institution has been seen in places like Cleveland, Ohio, where the Evergreen cooperative lettuce growers and commercial laundry had the long term anchor institutions of the Cleveland Clinic, University Hospitals and Case Western Reserve University. Another major part of the literature regarding the economic viability of cooperative enterprises can be seen in the debates among scholars as to whether the most important factor in cooperative sector development is access to capital from finance ears, or whether local institutions can supplement any funding deficiencies. My methodological practices in this ongoing project involve the conducting of in depth semi structured interviews with member owners or employee owners of cooperative firms in the Northern Virginia region. Due to constraints on times and challenges. With approval from the internal review board, I’ve conducted an interview with members of a single firm. For the sake of people safety and anonymity, the name of this firm will not be stated. I will now explore some of the recurring themes that develop through the interview. The first of these is the lengthy process of requesting support. One of the interviewees mentioned that the process for receiving a grant took five years. So the process of requesting and receiving support from a local institution often requires patience and the need to wait to obtain initial capital and create a firm. Second, eligibility requirements can often be a hindrance to funding. A major challenge of this cooperative face was that despite being a mission driven firm in the same manner as a nonprofit would be their existence as a for profit institution meant that they were ineligible for a great deal of funding opportunities. The third of these issues is financing strategies and grants. Grant financing was really only a small part of the entire budget of this cooperative participant. The major source of funding was the use of member loans, in which multiple member owners of the firm took out loans to finance the business. This strategy of pulling capital is apparently common among cooperative startups. The fourth of these is very important, which is that your audience matters. Another recurring theme was that the audience of a cooperative firm is incredibly important. For example, there were many challenges related to potential financiers not understanding the model of a cooperative. And there also have been concerns regarding the political orientation of a cooperative firm.

Unknown Speaker 4:27
Here’s some key quotes that can help corroborate the themes of these cooperatives. First is that that is probably one of the biggest challenges for a co op is that banks and other businesses don’t understand the model. Thus, a major hurdle for cooperative firms is to receive support is increasing awareness of the existence of the cooperative model and how they function as a firm. Second is that we have made a very, very explicit or concerted effort to wherever possible stay out of politics. This was an initially surprising quote to me. But it fits into the recurring theme of knowing one’s audience. The avoidance of major political issues may not be a generalizable strategy, but it was still an interesting method used by this particular firm. Now move on to some of the limitations of the project. In the preliminary phase of the study, the sample size was that of three. So this is not a generalizable sample, but it does gather some interesting preliminary insight into the state of the cooperative sector. This research can also be eventually supplemented with quantitative data collection, though this was not necessarily in the scope of this particular project. In terms of future research, future research would be more interviews. It would also involve documenting grants and financial agreements of cooperative firms in order to have some more of a quantitative element to the research. In conclusion, the cooperative sector in Northern Virginia has the potential to be a thriving part of the local economy. But this requires reduction in bureaucratic hurdles and greater assistance navigating the particularities of funding and grant making. Finally, I would like to have some acknowledgments. So I would like to thank my mentor, Dr. Ben Mansky, and thank Oscar for funding the project and also thank the internal review board for cooperation with this research. This is my references. Thank you

Undergraduate Research Scholars Program (URSP) - OSCAR

Exploring the impact of Oxytocin on KCC2 expression in mature neurons

Author(s): Stuart Murdoch

Mentor(s): John Cressman, Physics and Astronomy Department

KCC2 plays a vital role in removing chloride (Cl) from neurons, thus allowing inhibitory neurons to depolarize. When KCC2 is overwhelmed, Cl rises inside of the neurons, and the cells fail to stop incoming signals. Lower KCC2 levels have been linked to epilepsy and raising KCC2 reduces seizure likelihood. In young neurons, KCC2 is not fully expressed, so Cl builds inside of the cell. At birth oxytocin is released, increasing expression of KCC2. Strangely, this effect is not seen in neurons which have already undergone this switch. We wish to see if the buildup of Cl inside of the neurons allows for oxytocin to elicit an upregulating effect on KCC2. By inducing a seizure in mature mouse hippocampal cultures while administering oxytocin, we will overwhelm the KCC2 transporters and see if oxytocin resumes an upregulating role. Immunofluorescence will be used to compare the intensity of light from the cells autofluorescence, and the dye attached to the KCC2 to quantify the change. While our experiment has not yet started, upregulating KCC2 with oxytocin could lead to a novel approach for those who are resistant to traditional seizure treatments.

Hello, my name is Stuart Murdoch, and I am an undergraduate Physics major. Over the last semester, I have been working with my mentor Dr. John Cressman to investigate new ways to mitigate seizures by upregulating KCC2 in adult brains. Low KCC2 levels have been shown to increase seizure likelihood and severity.
Now you might say “hold on, don’t we already have anti-convulsant drugs for epilepsy?” and while this is true, a CDC survey, found that almost 40% of people with epilepsy are resistant to current treatments. Therefore, there is certainly still a demand for new methods of seizure control. After learning about the impact of KKC2 on seizures, I read through research surrounding ways that the body naturally increases KCC2 expression. Studies have shown that hormones play a key role in kickstarting the production of KCC2 in developing brains. Since the side effects of hormone exposure are well understood in humans, I decided to see if hormones could be used to upregulate KCC2 in adult brains as well. After searching through some more literature, I found that hormones seem to only upregulate KCC2 in developing brains and that the effect falls off with age. This naturally causes one to ask what is different in the young brain that allows hormones to impact KCC2?
Since there is a low abundance of KCC2 in the early brain, chloride is pumped into neurons causing inhibitory neurons to depolarize in response to the neurotransmitter GABA. However, in adults, chloride is pumped out of the cells by the KCC2 resulting in a hyperpolarizing response to GABA. We hypothesize that this depolarizing response to GABA may be necessary for the hormones to influence KCC2 levels. Interestingly, these inhibitory cells can become overwhelmed in a seizure when repeated exposure to GABA causes chloride to be pulled into the neuron faster than the KCC2 can remove it. When this occurs, the GABA response switches, and the neurons depolarize again. Due to this, we suspect that neurons undergoing a seizure while being exposed to the hormone oxytocin will experience an increase in KCC2 expression.
Our original experimental design involved obtaining brain slices from adult mice, and then incubating them with testosterone and a convulsant simultaneously and then comparing their KCC2 levels to control slices. However, after reviewing more literature I discovered that the hormone oxytocin has also been shown to increase KCC2 in young mouse brain cultures. This immediately caught my attention as working with oxytocin and brain cultures has many benefits. Mainly, we did not need to obtain approval to conduct an experiment involving live animals or approval to use testosterone which is a scheduled drug.
Our new experiment will utilize mouse hippocampal cultures that have been allowed to mature, and oxytocin in place of testosterone. Our four groups will receive either standard culture medium, medium with oxytocin, medium with 4-Aminopyridyne (our convulsant), or medium containing both oxytocin and 4-ADP for ten minutes before having their medium switched out for standard medium.
After treatment, our slices will be fixed, and stored for analysis. In order to quantify the change in KCC2 expression, we will use a technique called immunofluorescence. A primary antibody that binds specifically to the KCC2 protein will be applied to the cell cultures first. After the primary antibody has bound to the KCC2, a secondary antibody that has a fluorescent dye conjugated to it will be bound to the primary antibody. Now that a fluorescent dye is attached only to the KCC2 proteins, the fluorescence from the dye can be compared to that of the tissues natural autofluorescence. Finally, the difference between the two fluorescence’s intensities will be recorded.
We expect to see that the group exposed to oxytocin and a convulsant will have the highest fluorescence difference out of all the groups. This will indicate that the depolarizing response to GABA is necessary for oxytocin to upregulate KCC2. If this effect is observed, then I plan on sharing my results though a journal that accepts undergraduate research. This project is very important to me personally for two reasons. Firstly, I find the crossover of physics and the brain fascinating and would love to contribute a new discovery to the field. And secondly, I gain a lot of satisfaction knowing that the work we are doing may directly improve the lives of others someday. This research will not only shed light on to why oxytocin only effects KCC2 levels in young brains but may also benefit those who are resistant to traditional treatments for epilepsy.

College of Humanities and Social Science Honors College Undergraduate Research Scholars Program (URSP) - OSCAR

Intersectional Effects of Race and Gender on Age of Special Education Service Receipt

Author(s): Maharun Mia

Mentor(s): Adam Winsler, Psychology

Early diagnosis of autism spectrum disorder is important for providing early intervention for children, which significantly improves future outcomes. Race and gender have shown to correlate with differential age of diagnosis for children with ASD; the male-to-female ratio of autistic individuals in the US is 4:1, and there have been studies indicating that females often have a later Age of Diagnosis (AOD) than their male counterparts. However, there have been conflicting results in previous studies regarding the effect of race on AOD, as well as a lack of studies focused on any interactive effects between race and gender. This study will determine whether race and gender have intersectional effects on the AOD of autistic children, operationally defined as the grade level at which a child with autism first receives autism as their primary exceptionality classification in the public school system for special education service receipt. Data will be drawn from the Miami School Readiness Project, a large-scale and ethnically diverse longitudinal study of children that attended Miami-Dade County Public Schools. A subsample of students that had received autism as a primary exceptionality classification will be taken and a multiple regression analysis will be performed to determine the relationship of race and gender with the grade level at which students first receive their autism exceptionality. The analysis will control for poverty status, Dual Language Learner status, and behavior/cognitive functioning levels. This analysis will address 1) Is the age of special education receipt for ASD in schools similar between males and females? 2) Is the age of special education receipt similar between White, Black, Asian, and Latino children? 3) Are there any intersectional effects between race and gender on the age of special education service receipt? 4) Are certain intersectional groups likely to receive a different primary exceptionality before their ASD exceptionality?

Hello, my name is Maharun Mia and I’ve been working with Dr. Adam Winsler from the George Mason Psychology department on a project about the intersectional effects of race and gender and age of special education services received for autistic kids.
Autism is a neurodevelopmental difference identified by difficulties in socialization and characterized by repetitive, frequent behaviors and activities. It exists on sort of a spectrum so it varies between individuals of their symptom severity and what kind of behavior they’re exhibiting. The age of diagnosis for autism decreased as we learned more about it. So from 2006 to 2018, in the US, the age of diagnosis decreased from 61 months to 53 months. This is important because having an early-age of diagnosis means that these kids can attain early interventions and therapies that better outcomes in terms of socialization and behavioral functioning that betters their quality of life.
There’s a higher identification rate of autism in males rather than females, this ratio of male-to-female autistic populations is about 4:1. We have found that there’s an older age of diagnosis for females compared to males.
For race and age of diagnosis, the connection is less clear; there are some contradicting conclusions. However, we do know that there’s over and under-representation of different race categories within autistic populations. Autism tends to be more prevalent among white kids rather than black or Hispanic kids and this could also indicate differential age of diagnosis. As this could mean that black or Hispanic kids are getting diagnosed later than white kids or just going undiagnosed.
Intersectionality is the framework that I’m approaching the study from. Intersectionality is this theoretical framework that looks at how a person’s socio-political identities overlap to create a unique system of privilege and oppression. It’s important in the terms of autism diagnosis and service attainment, as this means that intersectionality could be creating these steeper barriers to attain these treatments and a better quality of life for specific intersectional groups such as black females, Latina females, etc.
For my current study, I will be using Special Education Service Receipt as my operational definition for the age of diagnosis in this study. While this is a little bit different from age of diagnosis, this is when these kids are actually receiving their services in schools for autism. My main purpose is to identify any race or gender effects on the timing of primary exceptionality attainment. Primary exceptionality is when they receive that category that allows them to receive the services.
I will be using data from the Miami School Readiness project. This was a large-scale, longitudinal, and ethnically diverse study that contains five cohorts of students and it is majority black and Latino. Only students who have ever had a primary exceptionality for autism from grades K-12 will be included.
My independent variables are race and gender. My dependent variables are the timing of primary exceptionality attainment and I will be controlling for poverty status, dual language learner(DLL) status, and behavioral cognitive functioning scores at age 4, as these have shown in the literature to have an impact on the age of diagnosis.
For my data analysis, I’ll be performing a hierarchical multiple regression model. So for the first level, it will just be the intersection of race and gender, then the second level will then include poverty and DLL status, and lastly will include the cognitive behavioral functioning scores as covariates. I’m hoping to continue this research next semester and finish my data analysis and then continue on to write my thesis and have it published, at some point, in a journal and present my results at conferences.

College of Engineering and Computing Undergraduate Research Scholars Program (URSP) - OSCAR

Mechanical and Surface Integrity Study of 3D-Printed PLA/ HA Composite

Author(s): Alexander Stuart

Mentor(s): Ali Beheshti, College of Engineering and Computing

The materials currently used to construct replacement hip and knee joints for humans are stainless steel and titanium. Whilst these materials are strong and fairly biocompatible, they are expensive and can cause adverse long term side effects such as stress shielding. The aim of this project was to construct and evaluate an alternative to these materials, specifically 3-D printed Polylactic Acid and Hydroxyapatite composite (PLA-HA). PLA-HA is a polymer composite of Polylactic Acid (PLA) and Hydroxyapatite (HA). PLA-HA is relatively cheap, very biocompatible, and can be easily adapted for use in a 3-D printer. This vastly simplifies the process of manufacturing unique parts with complex geometries such as a replacement joint. Raw PLA-HA was created in-lab using three different manufacturing methods. These manufacturing methods were Dry Speed Mixing, Wet Speed Mixing, and Magnetic Stirring. The raw PLA-HA was then converted into filament for use in a 3-D printer using a uniaxial filament press. The PLA-HA filament was then to be used to 3-D print three different samples for mechanical testing for each manufacturing method. These samples will be subjected to a variety of tests to characterize their mechanical and surface properties. These tests include destructive tensile tests, micro-indentation, and wear tests. These mechanical and surface properties will then be evaluated to determine if they are sufficient for a joint replacement application. The four different manufacturing methods will also be compared against one another to determine which method produces samples with the desired mechanical properties and distribution of hydroxyapatite throughout its matrix.

Hello!
My name is Zan Stuart and today I will be discussing my project which was a study of the mechanical and surface integrity of 3-D printed PLA-HA composites. The main motivation behind this project is the orthopedic and biomedical industries. Currently stainless steel and titanium are used for most replacement joints such as hip and knee joints. Now these materials are both strong and don’t corrode, but they are far from perfect for this application, as they often can cause adverse side effects such as stress shielding which weakens the bone surrounding the replacement joint.
PLA-HA, or polylactic acid combined with hydroxyapatite composites are being explored as a viable alternative, as they’re very inexpensive relative to the current options, they exhibit mechanical properties similar to that of bone, which eliminates the effects of stress shielding which I mentioned earlier. They have enhanced biocompatibility due to the fact that hydroxyapatite constitutes a major part of our bone structure, and they can be easily adapted for use with a 3-D printer which allows for the construction of unique parts with complex geometries such as a replacement joint tailored for any given individual.
The experimental process that I’ll be following is creating a base PLA-HA composite using four different manufacturing methods, which are dry speed mixing, wet speed mixing, magnetic stirring, and dry mixing. This raw material will then be extruded into a useable filament for a 3-D printer, and then three samples for each of the aforementioned manufacturing methods will be 3-D printed. Mechanical and surface property tests will be performed on these samples, and the results between the manufacturing methods will be compared.
Filament extrusion took place using a Noztek Pro high temp. uniaxial filament compressor. Raw material, which usually takes the form of pellets off the shelf, is fed into the hopper which you can see in the bottom right. In the bottom left of the hopper, you can see something that looks like a screw. That is the auger which then pushes the raw material through the heated nozzle which you can see in the bottom left, which melts the raw material and compresses it into something that resembles a string. This is the filament to be used in the 3-D printer.
The first of the manufacturing methods that I will cover are wet and dry speed mixing which are both very similar. For wet speed mixing, PLA is combined with dichloromethane, which is a solvent, and left to dissolve until homogenous in a fume hood. This is then combined with hydroxyapatite and Dodecyltrimethoxysilane or WD-10. These are then mixed in the speed mixer which you can see on the right-hand side, until the mixture is homogenous. That mixture is then poured onto an aluminum tray under a fume hood and left to cure and solidify overnight. Dry speed mixing is essentially the same process, minus the liquid solvents of Dichloromethane and WD-10.
Magnetic stirring involves the combination of PLA and DCM once again, but this time in a large glass beaker with a magnetic stirring bead in the center. This mixture is then sealed with silicone paper, and left to dissolve until it’s homogenous. The stirring bead rotates to ensure that the mixture remains homogenous. After the mixture is observed for homogeneity, HA and WD-10 are added and left to stir once again until the mixture is homogenous. The mixture is poured onto an aluminum tray to cure overnight once again.
Dry mixing is a much simpler process. It involves combining raw PLA pellets with dry HA directly into the hopper of the filament extruder. After that is extruded into filament after a single pass, then that filament is shredded and once again passed through the extruder, hopefully the result being better distribution of HA in the PLA matrix.
Now the results for this experiment. I was able to produce raw material using magnetic stirring and wet speed mixing. I was also able to successfully extrude filament, and 3-D print a magnetic stirred sample. I was unfortunately unable to progress enough to A: print samples for all of the different manufacturing methods and B: I was not able to perform mechanical testing on the samples. We’ll get to exactly why momentarily. You can also see in the bottom right I printed part of a magnetic stirred sample, as you can see that sample is obviously not correct. We’ll get into the reasons why shortly.
Some obstacles that I ran into during this project include I ruined a couple batches of magnetic stirred material due to improper sealing of the beaker with the silicone paper. You can see an example of that in the bottom right. It basically solidified when I was attempting to mix it due to the solvent evaporating because of the bad seal.
The extruder’s temperature reading was also inaccurate, meaning that the heat applied wasn’t necessarily what you set it to, which caused problems with inconsistency.
The extruder frequently clogged which you can see on the right-hand side. That has more to do with how the raw material that I created was then shredded and then fed into the extruder, we’ll get into that later.
It was difficult to get a uniform diameter for the filament because of how it was being removed from the extruder. I was basically pulling it out by hand, as hard as I tried it was impossible to get an exactly constant rate of removal. That caused another inconsistency with the filament.
I was also ill for a one-week period, and the lab was closed for two weeks. That was back-to-back. I lost three weeks of time where I could be making more raw material or potentially extruding more filament.
In the future, if I was to repeat this project, I would revise the casting method for the raw material by pouring the mixture into some form of pellet mold. Like I briefly mentioned earlier, when you get this sort of material off of the shelf it often takes the form of a spherical pellet, which feeds into the extruder better. The raw material that I was using was basically shredded flat sheets of plastic which was far from ideal and caused the extruder to clog frequently.
I would use a more accurate method of measuring the temperature of the extruder so that I could ensure that I was consistent with the temperature.
I would also use an automatic spool which would remove the filament from the extruder at a constant rate removing the variable of me pulling it by hand.
Thank you very much for your time, and I hope that you enjoyed my presentation!