Ocean-bottom seismometers (OBSs) are known to record puzzling signals termed short-duration events (SDEs) at frequencies of 4-18 Hz. SDEs are harmonic and usually have a duration of < 1 s, lack the P and S waves of local earthquakes, and individual events are never recorded on multiple OBSs. These signals have been attributed to either biological activity from animals bumping the seismic sensors or gas bubbles moving beneath the sea floor. In this study, we assess these explanations for SDEs using data from the Cascadia Initiative, a major OBS experiment along the continental margin of the Pacific Northwest that lasted from 2011-2015. After manually calibrating the acceptable trigger amplitude for each station, I ran a recursive short term/long term detector over the year they were deployed. Some shallow stations show a clear diurnal signal with more SDEs during the day, which is consistent with a biological origin, while others show no such pattern. SDEs are also observed on some of seismic stations on the Ocean Observatories Initiative Regional Cabled Array where the sensors are buried and protected from the biological bumps. I categorized the SDEs on representative stations based on parameters including the average frequency, bandwidth, number of peaks, and duration. This data will be used to determine whether the characteristics of the events show a pattern consistent with the biological or gas bubble hypotheses.

Submarine volcanoes make up 80% of volcanic activity on Earth, but are relatively understudied due to the lack of real-time observations of eruptions and their inaccessibility, often several kilometers below sea level. Underwater volcanoes behave differently than their land counterparts due to the cold sea water surrounding them. Some submarine volcanism is violent as water pours into active vents, rapidly cooling lava and shattering it into fragments. Other eruptions can produce lava flows that extend tens of several kilometers before solidifying. The majority of submarine volcanoes occur in areas of tectonic activity such as mid-ocean ridges and hotspot island chains. One interesting site of submarine volcanic activity is the Submarine North Arch Volcanic Field 100 kilometers north of Oahu, Hawaii, hosting a few of the longest flows on Earth and covering over 25,000 kilometers². The field is associated with the Hawaii hotspots but the source of such extensive volcanism is poorly understood. Past studies have mapped the volcanic field flow but only at low resolution. The southeast portion of the field comprises of a series of lengthy flows, hypothesized to emanate from a 75 kilometer long fissure in the seafloor. However, the resolution of the maps was too low to test this theory. On the R.V. Thomas G. Thompson, our team used the high-resolution Kongsberg EM302 30-kHz multibeam echosounder to map the eastern boundary of the southeastern lava flow where the fissure would likely be located. Although area covered was limited by bad weather, we were able to map a 6 kilometer wide swath track extending 63 kilometers along the inferred fissure. We identified the presence of two features that were potentially part of the fissures. Each extends about 1-2 kilometers and comprise a 5 meter deep and 200-400 meters wide trough with a levee on either sides. 

Alcohol withdrawal exists as a significant barrier to care for those who struggle with alcohol use disorder. Furthermore, there is evidence of worsening withdrawal symptoms after repetitive cycles of alcohol use and abstinence. Our preliminary research points to neuroinflammation primarily regulated by microglia, the immune cells in the brain, as a potential causal component in the escalation of recurring alcohol withdrawal symptoms. Previous work in our lab has shown that mice subjected to chronic intermittent exposure (CIE) to ethanol vapor showed elevated markers of neuroinflammation, as evidenced by transcriptome analysis in microglia. We found that the “unfolded protein response (UPR)” was activated; it plays a critical role in the development of neuroinflammation, and the UPR is mediated significantly by the C/EBP homologous protein (CHOP) an apoptotic transcription factor. Therefore, we hypothesize that CHOP in microglia is necessary for promoting alcohol withdrawal symptoms. We expect to observe measurable reductions in the withdrawal symptoms experienced by transgenic male and female mice with and without CHOP following CIE exposure. In our pilot study, transgenic male and female mice with and without CHOP were subjected to five weeks of CIE to ethanol vapor and then tested for withdrawal phenotypes. These tests include body temperature, locomotion, marble-burying behavior, novelty suppressed feeding, and sucrose preference. We have also characterized microglia morphology and CHOP expression in pilot mice brains. Having measured changes in these mice's neuroinflammatory mechanisms and subsequent behaviors, our results will determine the efficacy of decreasing CHOP gene expression to ameliorate the kindling effect in alcoholics. Therefore, our work provides a promising direction in tackling the inescapable cycle of worsening alcohol withdrawal that limits the road to recovery for alcoholics.

Located 100 km north of Oahu and over four kilometers of water, the North Arch Volcanic Field covers an area of 25,000 km² and includes the longest known underwater lava flow. A transect was mapped within the southernmost part of the field using a 30 kHz EM302 multibeam echosounder and 3.5 kHz Knudsen echosounders aboard the R/V Thomas G. Thompson. These surveys yielded a high-resolution bathymetric map and sub-bottom profiles that image shallow structures beneath the ship’s track. This research is investigating the extent and characteristics of these lava flows, as well as ability of Knudsen data to determine the location of flows. The seafloor is 300 meters shallower within the northern parts of the study area, as the transect moved onto the Hawaiian Arch. The lava flows here are more extensive and presumably closer to the eruptive source. Through the analysis of the Knudsen data, 29 lava flow crossings were found that vary in width and height. The lava flows have complex flow morphology, including different boundary structure, sediment pockets, complex flow paths, and elevation changes. There are two main areas of flows within the southern part of the study site with differing characteristics that may be related to the lava viscosity. The lava field is more variable than expected, which suggests that even in the small region sampled, it was formed by several effusive events over a period that had lava with different chemical properties. This work has shown that Knudsen data is extremely useful in classifying marine lava flows, and the further classification of the flow morphology of these lava flows can contribute to the understanding of the history of volcanism within the area, as well as marine effusive lava flows.

The North Arch Volcanic Field lies north of O’ahu, covering 24,000 km² of seafloor. It is a part of the greater Hawai’ian Arch, a region of uplifted seafloor surrounding the Hawai'ian hotspot. The North Arch is a fairly recent discovery, with little known about it. It is a product of recent basaltic volcanism, the mechanism of which is not understood. The magnetic minerals found in basalts retain the signature of the Earth’s magnetic field at the time they cooled. Thus, basaltic lava flows generally have high remnant magnetization, distinguishing them from the surrounding, weakly-magnetized sediments. My objective was to use a magnetometer to assess the feasibility of using magnetic anomalies to determine the thickness of lava flows in the southern North Arch. On board the R/V Thomas G. Thompson, a sub-bottom profiler and multibeam sonar system were used to resolve lava flow boundaries while I collected data with a towed magnetometer. The ship followed 5 east-west track lines before heading north-west along an inferred rift on the seafloor, then west to exit the field. I obtained magnetic anomalies by correcting the raw magnetic data with the International Geomagnetic Reference Field and a time series from Honolulu’s magnetic observatory. I then used a modeling program to compare observed anomalies with those predicted for lava flows of varying thicknesses. A modeled flow along the northmost track line yielded a flow maximum thickness of 50 m, thinning to 5 km towards the east edge of the field. The results show that the magnetic anomaly produced by these flows was strong enough to be detected and yielded flow thicknesses of tens of meters that are consistent with other observations. This research demonstrates that magnetometry is an effective tool for studying the North Arch Volcanic Field and could be used on other submarine volcanic fields as well.

Massive binary star systems influence the formation and evolution of galaxies through production of energy and heavy elements. These systems can evolve into X-ray producing high mass binaries: a neutron star or black hole accreting material from a high-mass companion. While high-energy mass accretion makes these sources especially important, it makes them exceedingly difficult to model. One extremely useful characteristic for testing models of their formation and evolution is their temporal variability. By observing the properties of these sources over time, we can directly compare observed variability against predictions from models. M33, a large spiral galaxy just under three million light-years away from the Earth, is home to a collection of these X-ray binaries, last catalogued in 2015. With the goal of constraining the variability of the binaries, I have analyzed five separate epochs of Chandra imaging data taken after the production of this catalogue. I compiled a preliminary list of observed X-ray sources in the images and used positions of the previously cataloged sources to correct the astrometry, ensuring consistent alignment among observations. I then selected the most accurate position estimate for each source by-eye. Combining data from all aligned observations, I have now extracted a catalogue of reliable source detections, as well as source properties such as position and flux. With these values, I have assessed source validity and created lightcurves to study their variability characteristics. Through this work, I have found a total of 56 bright sources that meet my criteria for validity, of which 49 sources were previously identified in literature and 7 sources are new, appearing only in our observations. Looking at the characteristics of both new sources and previously observed sources, I will constrain source variability to determine how much the X-ray binaries of M33 changed in brightness over the course of the observations.