2019 Issue

Editor in Chiefs: Grace Xiong, Meera Krishnamoorthy

Associate Editors: Jonathan Chan, Alycia Lee, Hana Kim, Sherry Wang, Michael Yao

Interviews:

Dr. Aaron Ames

Bren Professor of Mechanical and Civil Engineering and Control and Dynamical Systems


Articles:

Stabilization of an electro-optic modulator for quantum communication using a low-cost microcontroller, George Iskander

Abstract: We stabilize the intensity of the output of a high-bandwidth Mach-Zehnder electro-optic modulator using a low-bandwidth electronic control loop. Our design is based on the detection of light at the output of the modulator and performing a gradient-ascent algorithm that is programmed into a low-cost microcontroller. We measure an extinction ratio, which is the ratio of the maximum and minimum intensity of the output, of 22 dB over several hours, consistent with manual tuning over minute-long timescales. Finally, we discuss the application of our system for the generation of high-fidelity quantum bits for quantum communication.

Culture Conditions Influence Iridescence in Marine Microbes, J Livingston

Abstract: Iridescence, a type of structural color, is a biological phenomenon that depends on the natural formation of photonic crystals. While it is well characterized in multicellular organisms such as arthropods, it has not been as extensively cataloged among bacteria and its role in mediating microbial fitness is poorly understood. In this study, we isolated several iridescent bacteria from rocky shore seawater around Woods Hole, MA and identified them using genomic techniques. We used light microscopy to analyze the effect of differential culture conditions, including salinity, pH, and nutrient availability, on iridescence to better understand its biological significance using environmental variation within the ranges of their rocky shore habitat. Our preliminary results showed that nutrient availability influenced the structural color of iridescent bacteria. With the exception of low agar concentration or salinity, iridescence was observed in all conditions in which growth occurred, indicating that iridescence was a consequence of the growth pattern of these bacteria on solid media.

Phenotypic Analysis of Autism-associated mutations in C. elegans, Judy Kim

Abstract: In Autism Spectrum Disorder (ASD), missense mutations are prominent. Missense mutations occur when a single nucleotide change results in a codon that codes for a different amino acid. Because these mutations are so abundant, they are hard to study in many organisms. C. elegans, however, is an ideal, model organism to study missense mutations because of their short generation time, small size, transparency, invariant development, and stereotyped behavior. This study focuses on characterizing phenotypes of ASD-associated missense mutations in C. elegans by crossing different strains of C. elegans (lin-45 and unc-73) to generate the double mutants. We investigate the neurological function of lin-45/BRAF because while BRAF is well known as an oncogene, its role in ASD is unclear. Lin-45 is crucial for larval viability, fertility, and the induction of vulval cell fates. Moreover, lin-45, in conjunction with a protein kinase C (PKC) protein called kc-1, acts together to regulate a mechanosensory response called the nose touch response in C. elegans. The worms used in this project were all synchronized at the larval stage 4 (L4) stage. After new, synchronized double mutant strains were found, chemotaxis was performed to examine the worms’ attraction towards diacetyl and ethanol, and the data was compared to the wild-type N2 and CX3410 strains. We find that the odr-10 mutant had a higher chemotaxis ROI index than did N2 wildtype strain. With an α- level of .05 and a one-way ANOVA test, there was a statistically significant difference in the means of N2, unc-73(sy898);lin-45 (sy875), unc-73(sy896);lin-45 (sy875), unc-73(sy892);lin-45 (sy875); p < .05.