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Atlanta Science Festival After-Party Event Reflection

April 16, 2024

I joined STEMComm this semester because I was interested in writing articles centered around science and helping out with coordinating events. This semester I got the opportunity to work on the Atlanta Science Festival event after-party, particularly with the shrinky dink activity. I had a lot of fun throughout the entire process, starting with ideation to the final product. Initially, my group and I were uncertain what we wanted to do that would be scientific and fun. However, during the brainstorming, we decided to host a shrinky dink workshop. This turned out to be engaging and didn’t cost too much money. 

A shrinky dink is a toy that was invented in 1973 and was super popular in the 1980s. The process involves drawing one’s design on thin, flexible sheets of polystyrene (a type of thermoplastic), cutting it out, and then heating it thus shrinking it into a thicker, more rigid form (Gelfand). Polystyrene is a common plastic and is considered similar to recycled plastic #6 (Magazine). These sheets are created by extrusion, where the material is melted and die-cut into the final product (Gelfand). By heating the plastic, the long polymer chains in the plastic that are stretched out go back to their original state. As a result, the design “shrinks” to around a third of its size and is marketed as magic.

In our workshop, we cut the plastic sheets into smaller sections for the participants and had a variety of art materials. These included colored pencils, sharpies, markers, hole punchers, and scissors. The product options we decided on were keychains, pins, and magnets. To maintain a safe environment for everyone, we had some team members stationed with heating guns to do the shrinking process. This ensured no participants were harmed in the heating process. Additionally, we had resin that hardened under the UV lamp to create a more secure encasing and fun gloss layer if anyone wanted. The UV light cures the resin through a photochemical reaction. This process does not take too long, depending on how much resin is needed to harden. 

Before the event started, we also created several examples to display as well as posters and slideshows to explain the process of shrinky dinks, and resin. Once the event started, the workshop received many curious participants and positive feedback. All the participants were surprised and intrigued by the shrinking process. It was fascinating to see how small the designs became when heated up. While some designs became too small or shrunk a little funky, after a few tries, participants were able to grasp how large they should go with the design before shrinking. 

The workshop was a big success and many participants came back to make more than one item. I enjoyed the setup process and seeing the participant’s faces light up in delight during the event. Running the event and seeing the final product of all the planning come together was a rewarding experience. I am looking forward to helping coordinate and run more events in the future!

Sources Cited

Magazine, Smithsonian. “The Science of Shrinky Dinks.” Smithsonian.Com, Smithsonian Institution, 14 Oct. 2010, www.smithsonianmag.com/science-nature/the-science-of-shrinky-dinks-36715644/. Accessed 16 Apr. 2024.

University, Carnegie Mellon. “Shrinky Dinks – Gelfand Center – Carnegie Mellon University.” Shrinky Dinks – Gelfand Center – Carnegie Mellon University, www.cmu.edu/gelfand/lgc-educational-media/polymers/molecular-rearrangement/shrinky-dinks.html#:~:text=Prior%20to%20heating%2C%20the%20thin,while%20retaining%20the%20colored%20design. Accessed 16 Apr. 2024. 

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  Timothy Durham was convicted of rape when a test showed his DNA genotype matched the DNA recovered from the crime scene. Eye witnesses testified that Durham was in a different state at the time of the incident, but he wasn’t exonerated from his 3000 year sentence until follow up DNA analysis showed that the preliminary forensic analysis used in the trial was misinterpreted (Thomas et al.). DNA testing serves an invaluable part in our criminal justice system, but it comes with complications and bias that can lead to wrongful convictions and misinformed juries.  

Background:

Forensic genetics aims to identify the origin of a biological sample. It can be traced back to Karl Landsteiner who discovered human ABO blood groups. With blood groups, suspects could be eliminated based on their blood type. For example, if a suspect had type A blood and there was type B blood left at the scene by the perpetrator, the investigators could rule out the suspect. Unfortunately, the reverse didn’t work. If the suspect and perpetrator both had the same blood type, it can’t be concluded that the suspect was guilty. Blood identifiers evolved into 8 distinct categories which improved the ability to eliminate suspects, but could only conclude that (if the system matched) it might be the perpetrator or this person might be related to the perpetrator (Jobling and Gill). The field evolved in the 1980s with the discovery of Minisatellites, lines of repetitive DNA that don’t encode proteins. Minisatellite patterns in DNA create what we know today as the DNA fingerprint, and it has a much higher accuracy rate than previous methods (Augustyn et al.). Around the same time, a breakthrough for victims of sexual assault was discovered. In the case of assault, bodily fluids of both the victim and the assaulter can get mixed. A process called differential lysis was created which could selectively increase the concentration of sperm in a fluid sample thereby allowing for accurate DNA testing (Jobling and Gill). Forensics evolved to use single-locus probe testing after several years because of its ease of interpretation. It looked at specific minisatellites that had high variability between subjects. This was the first DNA-based method to be used in a criminal investigation. Two murder homicides from several years apart were connected using DNA evidence. The evidence was then used to exonerate an innocent man, and the guilty party was found when he tried to evade mandatory DNA testing for all men in the small town. His guilt was then reinforced when the DNA profiles matched, and he gave a confession (Jobling and Gill). Finding DNA at a crime scene doesn’t guarantee that you’ll find a murderer. There are issues with non-pure samples and limited samples that make DNA work difficult, and accreditation of facilities and new techniques and take time (Jobling and Gill).  

Subjectivity of DNA Interpretation:

In a 2009 publication, the National Academy of Science discusses the possibility for subjective influence in lab based forensics. The interpretation bias happens in complex cases where, for example, there could be a mixture of DNA. A study published in 2011 looked specifically at this issue. A gang rape happened in Georgia, and the mixture in DNA from the case was used to prosecute one suspect after another suspect took a plea bargain to testify against him. With DNA mixtures, there are three possible conclusions: suspect excluded, suspect cannot be excluded, and inconclusive. If the suspect is excluded, it means that there’s little to no possibility that his DNA is part of the sample. If the suspect cannot be excluded, it means that there’s a possibility that his DNA is part of the sample. In the trial, the DNA examiners who knew the context of the case concluded that the suspect being prosecuted could not be excluded. The 2011 study gave the DNA evidence from this case and the DNA profiles of the suspects to 17 forensic examiners. These examiners had no context of the case, and they all worked independently. Of the 17, only 1 came to the same conclusion (suspect cannot be excluded) as the examiners who knew the context of the case. Twelve of the 17 concluded that the suspect who was prosecuted and convicted had no relation to the DNA found in the sample. Not only does this show that subjectivity occurs due to the context of the case, but the 17 examiners came up with different findings based on their past experiences meaning that not all DNA analysis is objective. Some organizations like the Scientific Working Group on DNA Analysis Methods say that quantitative statistical evidence should be presented with every categorical conclusion, but the US doesn’t require this (Dror and Hampikian).

False Positives:

There are two categories that cause wrongful identification in a DNA report: coincidental matches and false positives. Coincidental matches are DNA matches between two unrelated people. The probability of these matches is about 1 to 500,000 for white individuals and about 1 to 350,000 for black individuals. This small probability of coincidental matches makes people feel confident in DNA evidence. False positives, on the other hand, are matches between DNA and test DNA that result from issues in the forensics lab. There have been multiple cases of forensics labs accidentally switching victim and suspected rapist DNA which lead to convictions that were later overturned when the lab realized the error. There are also cases of misreading or misunderstanding a sample. In a case from 1993, a man was convicted of rape because someone interpreted a mixed sample of victim and perpetrator DNA as an individual sample. The conviction was again overturned. To prevent false convictions, retesting DNA is allowed, but it’s not an efficient solution. Many people are pushing for statistical information on the probability of false positives, so that the jurors can make accurate judgements based on DNA evidence (Thomas et al.).  

Conclusion:

DNA analysis is a useful tool for the criminal justice system, but subjectivity can be an issue in forensic testing. To combat wrongful convictions, there are organizations like The Innocence Project who use DNA testing to free the innocent, but reformed forensic testing standards should be put in place to prevent subjectivity and to ensure juries are correctly informed during trials. https://www.innocenceproject.org/    

Citation:

Augustyn , Adam, et al. “DNA Finerprinting.” Encyclopedia Britannica , 26 Apr. 2018, www.britannica.com/science/DNA-fingerprinting#ref153186. Dror, Itiel E., and Greg Hampikian. “Subjectivity and Bias in Forensic DNA Mixture Interpretation.” Science & Justice, vol. 51, no. 4, 2011, pp. 204–208., doi:10.1016/j.scijus.2011.08.004. Jobling, Mark A., and Peter Gill. “Encoded Evidence: DNA in Forensic Analysis.” Nature Reviews: Genetics, vol. 5, no. 10, Oct. 2004, pp. 739–751., doi:10.1038/nrg1455. Thompson, William C, et al. “How the Probability of a False Positive Affects the Value of DNA Evidence.” Journal of Forensic Sciences, vol. 48, no. 1, Jan. 2003, pp. 1–8., doi:10.1520/jfs2001171.