2017 Abstract Book Ionized and Molecular Gas in IC 860: Evidence for an Outflow Carson Adams Mentors: Katherine Alatalo and Anne M
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2017 Abstract Book Ionized and Molecular Gas in IC 860: Evidence for an Outflow Carson Adams Mentors: Katherine Alatalo and Anne M. Medling Galaxies at present-day fall predominantly in two distinct populations, as either blue, star-forming spirals or red, quiescent early-type galaxies. Blue galaxies appear to evolve onto the red sequence as star formation is quenched. The absence of a significant population falling in the intermediate ‘green valley’ implies that these transitions must occur rapidly. Identifying the initial properties of and pathways taken by these ‘dying galaxies’ is essential to building a complete understanding of galactic evolution. In this work, we investigate these phenomena in action within IC 860 — a nearby, early-type spiral in the initial stages of undergoing a rapid transition in the presence of a powerful AGN-driven molecular outflow. As a shocked, post-starburst galaxy with an intermediate-age stellar population which lies on the blue end of the green valley, IC 860 provides a window into the early stages of galaxy transition and AGN feedback. We present Hubble Space Telescope imaging of IC 860 showing a violent, dusty outflow originating from a compact core. We find that the mean velocity map of the CO(1-0) from CARMA suggests a dynamically excited bar funneling molecular gas into the galactic center. Finally, we present kinematic maps of ionized gas emission lines as well as sodium D absorption tracing neutral winds obtained by the Wide-Field Spectrograph. Moving Mass and Mechanical Clutch Mechanisms for One-Dimensional Hopping Robots Sara Adams Mentors: Aaron Ames and Eric Ambrose There are a number of potential mechanisms to create a hopping motion in robots, but not many are energy efficient. By developing energy efficient mechanisms for hopping robots, we allow future robots to have more flexibility doing work in the field, as they can be powered by batteries rather than a tether to an external power supply. Using a spring for hopping allows us to take advantage of restorative spring forces, but deformation and friction still cause energy losses that necessitate the use of an actuator to maintain a consistent hop height. Thus, we compared the functionality and efficiency of a moving mass mechanism and a mechanical clutch for compressing the hopper’s spring in order to maintain a hop height of six feet. Use of Antibiotics as Synthetic Modules for Regulating Bacterial Growth Swati Agrawal Mentors: Richard Murray and Reed McCardell The intricate network of interdependencies driving the operation of biological ecosystems yields capabilities which are largely realised through coordinated community behaviour. It is some of these competitive interactions that we wish to investigate using synthetic growth regulators such as secreted antibiotics and quorum sensing modules. We conducted experiments to assess the dynamic range and kinetics with which antibiotics inhibit cell growth and how tetracyclin (aTC) inducible resistance genes subvert the effects of this toxicity. In an antibiotic gradient experiment with cells lacking resistance genes, the cells showed, albeit with varying profiles depending upon the antibiotic used, complete inhibition of growth on a 24-hour time scale. To explore the phenomenon of rescue, cells transformed with inducible resistance were incubated with a constant antibiotic concentration and an increasing gradient of aTC (0 – 200 ng/µL) was applied. This was performed with a series of antibiotic concentrations. Results indicated that these potentially resistant cells apart from responding to the rescue operation at appreciable aTC levels surprisingly escaped growth arrest even without induction. As the copy number of the plasmid carrying the resistance gene grew larger, effects of this escape became more pronounced and were noticed in antibiotic concentrations as high as 300%. From these observations, we hypothesised the existence of a basal level of resistance accruing from leak of expression from our plasmid compounded by the effect of copy number. In another setup, a pulsed addition of aTC over a time interval of 24 hours to cells already incubated with a constant antibiotic concentration was also successful in reviving cell growth. The antibiotics used in this study were Carbenicilin, Chloramphenicol and Kanamycin, and DH5αZ1 cells provided the cellular chassis. Probing the Dynamics of SGTA/2, a Chaperone Protein Involved in Membrane Insertion of Tail-Anchored Proteins Rita Aksenfeld Mentors: William Clemons and Michelle Fry The chaperone protein SGTA (and its archaeal homolog, Sgt2) dimer is an integral part of the guided entry of tail anchored proteins (GET) pathway that protects the transmembrane domain of tail-anchored (TA) proteins from the aqueous cellular environment. While it is known that the C-terminal domain of SGTA is the binding site for TA proteins, a structure of this region has not been obtained. Based on data previously collected in the Clemons group, we hypothesize that the C-terminal domain of SGTA has a disordered structure that becomes ordered upon binding. To demonstrate this, a construct containing the C-domain of SGTA was created and expressed in E. coli The SGTA C-domain was purified by nickel column and size exclusion chromatography, and mass spectrometry will be used to confirm its presence. This will be repeated in the presence of TA protein so that a complex forms. We 1 will perform 1H - 15N HSQC NMR spectroscopy to measure the relative disorder of SGTA alone and in complex with a TA protein. If that yields inconclusive results, differential scanning calorimetry will be performed to measure the difference in enthalpy between SGTA alone and in complex with a TA protein. Inducing Habits in Humans Through Overtraining Mladena Aleksic Mentors: John P. O’Doherty and Eva R. Pool In contrast to goal-directed behaviors, which are driven by the representation of their consequences, habits are outcome insensitive behaviors elicited solely by situational cues. This study aims at inducing habits in humans during a free operant task through an overtraining procedure. Sixty participants pressed keys to accumulate food outcomes during the presentation of outcome-associated stimuli. The task was administered to two groups: one group was trained moderately whereas the other group was trained extensively (i.e., six times more). Following the training, both groups underwent a devaluation procedure, in which the outcome value was reduced through selective satiation. The pressing frequency before and after the devaluation procedure was measured to reflect behavioral sensitivity to the outcome value and compared between the two groups. We expect the moderately trained group to flexibly adapt their behavior to the outcome value by diminishing key pressing for the devalued outcome after satiation; and we expect a reduction of this behavioral sensitivity to outcome value in the overtrained group. This study will enable us to determine the extent to which an overtraining procedure can induce habitual behavior in humans. Integrating and Testing Simulations Designed for the Dark Energy Spectroscopic Instrument Thomas Alford Mentors: Klaus Honscheid and Tim Eifler The DESI (Dark Energy Spectroscopic Instrument) project is an endeavor to measure dark energy and its effect upon the expanding universe. DESI mainly looks at baryonic acoustic oscillations and redshift-space distortions and uses these to measure the effect of dark energy on the universe. DESI is scheduled to begin measurements in 2018 at the Mayall 4-meter telescope at Kitt Peak National Observatory. The DESI control system ensures that DESI aligns itself correctly after each image it receives from the telescope in preparation for the next. My project focused on creating simulations of images for the control system. Initially, these image simulations were simple NumPy arrays filled with random values. I created a program that simulated actual images of stars, donuts (out of focus images of stars), and spectra, which I then integrated with the rest of the code running the control system. This control code can then be tested with the simulations to ensure that each part of the system runs smoothly before it takes real data in 2018. Approximating Feedback Vertex Sets in Tournaments Ayya Alieva Mentors: Virginia Williams and Adam Sheffer The Feedback Vertex Set problem is a well-known problem in discrete mathematics. In a directed graph, a feedback vertex set is a subset of vertices S such that the graph obtained by removing S has no directed cycles. The problem of finding a polynomial-time algorithm for extracting a minimum feedback vertex set from a graph is called the Feedback Vertex Set (FVS) problem. It is one of Karp's 21 NP-complete problems. A graph T=(V,E) is a tournament graph if it is a complete directed graph (such that for any two vertices v, u in V, there is exactly one edge either from u to v or from v to u). The FVS problem remains NP-complete in such graphs. In 2016, Matthias Mnich, Virginia Vassilevska Williams, and Laszlo A. Vegh showed a 7/3 approximation algorithm for the Feedback Vertex Set problem generalized to allow for nonnegative vertex weights. This was an improvement on the previously known 5/2 ratio. My research concerns the above problem. If successful, my research will lead to a (2+epsilon)-approximation algorithm for all epsilon > 0, which is optimal under the Unique Games Conjecture. Robust Control Synthesis From Temporal Logic Specifications Rijad Alisic Mentors: Richard M. Murray and Sumanth Dathathri Synthesizing correct-by-construction policies from a given Temporal Logic Specification for an autonomous system requires knowledge of the high-level environment behavior. These synthesis algorithms often produce only one policy out of a set of possible ones, without a way of comparing them to each other. By bringing this framework out into the physical world one would need to consider noise and unpredictability as well. The impact of these uncertainties could be dealt with by identifying abstractions that could improve the robustness of control policies during the synthesis or by identifying which policies will be less affected by them.