Nicole Hellessey, Ph.D.
School of Biological Sciences
Georgia Institute of Technology
ABSTRACT
Antarctic krill (Euphausia superba) is a key component of the Antarctic food web with considerable lipid reserves that are vital for both their own and higher predator survival. Krill feed on diatoms, dinoflagellates and other algal species year-round, resulting in high omega-3 polyunsaturated fatty acids which are essential for krill health, growth and reproduction. Krill-derived omega-3 containing products (particularly eicosapentacnoic acid (20:5w3) and docosahexaenoic acid (22:6w3)) are sold as nutraceuticals for human consumption. Krill oil tablets (sold as an omega-3 supplement) are now one of the fastest growing nutraceuticals globally. However, few attempts have been made to link the spatial and temporal variations in krill lipids to those in their food supply. Knowledge of krill diet and krill lipid dynamics is lacking for the Indian and Pacific Oceans, as most studies have focused on the South Atlantic Ocean sector where the krill fishery is based. Most research voyages are conducted during the summer and all scientific studies are restricted in their spatial and temporal scales. Another major gap in current Antarctic ecosystem models is the link between environmental drivers and their impact on primary production and therefore food availability. Satellite-derived data for biological and ecological measures is still developing as a tool although outputs such as ocean colour data which can be converted into chlorophyll a concentrations (a proxy for primary production), are becoming more common. This seminar will cover recent developments in the knowledge of spatiotemporal fluctuations of krill lipid biochemistry in relation to their environment.
Event Details
Kai Ziervogel, Ph.D.
Institute for the Study of Earth, Oceans and Space
University of New Hampshire
ABSTRACT
Marine snow aggregates are fast sinking vehicles of organic and inorganic matter that often form at the decline of a phytoplankton bloom, accelerating the vertical downward flux of biologically fixed atmospheric carbon to the deep ocean. Marine snow also incorporates and transports marine contaminants such as microplastics and spilled oil into the ocean’s interior. During sinking through the water column, aggregates are subject to biological and physical transformation, determining the export efficiency of marine snow-associated matter. I will present results from laboratory incubations on heterotrophic microbial degradation and physical fragmentation of marine snow and marine oil snow, emphasizing the importance of small scale processes in millimeter-sized aggregates on large scale implications for the ocean’s elemental cycling.
Event Details
Audrey Sederberg, Ph.D.
Department of Physics
Emory University
ABSTRACT
A central goal of neuroscience is to connect structure to function: to understand how neural activity and neuroanatomy control the actions, perception, and cognition of an organism. In recent years, there has been an explosion in the quantity and quality of neural data. Only ten years ago, recording simultaneously from a few dozen cells was notable, and now that number is in the thousands. We also know more about the intricacies of microcircuit anatomy, with detailed information on individual cell types and the patterns of connectivity among them. These data are exciting, but also raise challenging questions and require integrating precise, quantitative predictions into the analysis of large, complex datasets. In my talk, I will focus on two examples of how new directions in theoretical and data-analytic research can lead to novel insight into the function of neural circuits. First, I will show how minimally structured networks can capture many features of large-scale neural population recordings with surprising precision (within a few percent!), suggesting new approaches for linking structure to function. In the second part of the talk, I will show how we use prediction to extract essential features of a dynamic cortical state, a general approach that can be extended across brain areas and species to build a quantitative, comparative framework for the analysis of cortical dynamics. These are steps toward the ultimate goal of predicting, from the anatomy of a microcircuit, both the statistics of activity (e.g., selectivity, correlations, power spectra) that it generates and how that activity supports microcircuit computations relevant to behavior.
Event Details
Joseph Lachance, Ph.D.
School of Biological Sciences
Georgia Institute of Technology
ABSTRACT
Human genomes have been shaped by natural selection, population bottlenecks, and archaic admixture. These evolutionary processes contribute to hereditary differences in disease risk across populations. Here, I explore how disease risk has changed over time and address some of the challenges of applying precision medicine approaches to diverse global populations. My lab’s research fits into four broad themes: anthropological genetics, analysis of ancient DNA, population genetics of prostate cancer in Africa, and improving the transferability of polygenic risk scores. By combining genetic data with mathematical models and computer simulations, we have been able to infer the complex demographic history of diverse human populations (including evidence of sex-biased admixture and interbreeding with unknown “ghost” populations). My lab has also applied precision medicine approaches to ancient human genomes and used time series data to infer the strength of natural selection acting on disease-associated alleles. Differences in risk allele frequencies across populations can contribute to health disparities, including elevated rates of aggressive cancer in men of African descent. Research in my lab has focused on the evolutionary causes of this health disparity and the development of a novel genotyping array that is optimized for detecting genetic associations with prostate cancer in sub-Saharan Africa. Finally, genetic predictions do not always generalize well across populations. To address this challenge, we leveraged evolutionary information to improve the transferability of polygenic risk scores.
Event Details
This Town Hall is a follow up to the Science and Projections for our Return to Campus, held at the start of August. Professors Weitz and Gibson will explain the results of surveillance testing so far, share the need for ongoing vigilance and increased participation, and respond to questions from the community. Alexa Harter, CIPHER Director for GTRI, will also share information and answer questions about the NOVID app. Everyone is welcome! Join via BlueJeans Events. A recap of this talk will be posted to cos.gatech.edu.
Event Details
Minoru Shinohara, Ph.D.
School of Biological Sciences
Georgia Institute of Technology
ABSTRACT
Human motor function is impaired with neurological disorders and injuries such as spinal cord injury and stroke. Among others, reduced neural excitability of the motor cortex and unintended co-activation of antagonistic (i.e. opposing) muscles are the major neurological problems associated with the impaired motor function. Conventional rehabilitation strategies of repeating motion practice have limitations in regaining neuromotor function in clinical populations. Hence, novel approaches are needed that can further facilitate neuromodulation and thereby rehabilitation outcome. By considering neurophysiological integration in humans, we have designed unique approaches: noninvasive perturbations to the autonomic nervous system (i.e., orthostatic stress, afferent vagus nerve stimulation) for modulating corticospinal excitability and motor control, paired stimulation of the afferent and efferent nervous systems for modulating corticospinal excitability, and anti-phasic co-activation practice for modulating common neuromotor oscillations during voluntary contraction and motor control. I plan to discuss our experimental studies that have examined the efficacy of these unique approaches in healthy adults. The fundamental findings on the efficacy in healthy individuals have laid the foundation for studying the application of the new interventions to clinical populations.
Event Details
School of Biological Sciences professors Joshua Weitz and Greg Gibson will provide updates on Covid-19 projections and surveillance testing with a focus on the return to campus.
To join: https://primetime.bluejeans.com/a2m/live-event/jyyabssd
Event Details
This summer, Joshua Weitz, a professor with the School of Biological Sciences who is also the founding director of the Quantitative Biosciences Interdisciplinary Graduate Program (QBioS), organized a “Hands-On Modeling Virtual Workshop” focusing on epidemics.
The Weitz Group at Georgia Tech has created various models and figures to help explain the spread and epidemiology of Covid-19. Weitz has frequently shared his findings with local and national media outlets.
This year marked the fourth annual “Quantitative Biosciences Hands-On Modeling Workshop”. Due to Covid-19, the summer 2020 event was held virtually. Focused on the basics of epidemic modeling, the workshop was joined by more than 50 online attendees from around the globe.
Weitz delivered two lectures on epidemic theory and the latest Covid-19 research. In addition, ten QBioS students, two post-doctoral scientists from the Weitz group (David Demory and Stephen Beckett), and one external post-doctoral scientist (Bradford Taylor) served as instructors for small group sessions, focusing on the hands-on experience of coding deterministic and stochastic models to predict the spread of epidemics.
The QBioS Ph.D. student organizers collected surveys following the event, which provided feedback on both the content and format of the workshop. Some examples:
“The flow of the workshop is great. Learning introductory concepts to start, the ability to apply some of them with hands-on, and then finishing with applications and extensions. Having many participants from many backgrounds adds a lot to the small group sessions as well.”
“I thought it was a great workshop to get core concepts across. I think the online format was done as best as possible and appreciated the thoughtful instructors.”
Weitz and Pablo Bravo, a second year QBioS Ph.D. student in Quantitative Biosciences, share thoughts on how they ran the virtual workshop — along with ideas and advice for those looking to host similar online workshops:
What were the biggest lessons learned from your summer workshop?
Weitz: The survey results communicated two important lessons. First, positive
responses to the workshop structure reinforce just how critical it is to contextualize modeling in terms of a key biological challenge. Providing a biological scaffold helps to focus student work and keep their interest and attention on the technical material. The second lesson is that there is an adaptation period to hands-on learning online. We intentionally spaced out the coding sessions with a mid-day break and most of the issues appeared in the morning as students and instructors adjusted to their group's dynamic, including debugging code while in different locations, and indeed, countries.
Bravo: One aspect that made the workshop possible was the participation of many members in different roles: coordinators, advertising, lecturers, instructors, IT support. Planning and working early as a team were essential.
What were the biggest challenges you had to overcome?
Bravo: There were two main problems that we had to solve. First, we offered support for three programming languages (MATLAB, Python, R), and given the high number of registrations, the first year QBioS cohort couldn't handle all of them. Members of the QBioS community, current and past members of the Weitz group stepped in and helped us in leading activity groups. It wouldn't have been possible without them!
Also, debugging was an issue. Debugging scripts over video calls was extremely difficult. Attendees were not keen on screen-sharing their code at the beginning, but as they got to know each other, this stopped being an issue. Delay between the video and audio feed remained an issue throughout the whole workshop.
What’s the one takeaway you want to stress to instructors looking to offer similar webinars and online workshops?
Weitz: Overall, we are optimistic about our ability to continue to develop and implement innovative teaching strategies in QBioS — but remain realistic that adjustment periods will be needed to foster an atmosphere conducive to small group learning when groups are dispersed.
Bravo: I think the biggest factor in the success of the workshop is that it was centered around interactive activity sessions, in which five students and an instructor would go through the material and write the scripts together. This promoted both active learning and discussion between the attendees, and also allowed attendees to follow up with questions and comments to their respective instructors — even days after the workshop finalized.
Pages
