ColumbiaDoctors Outreach is presenting a men’s health awareness day, including educational materials, giveaways, and opportunities to ask questions and interact with care team members. The event will take place from 10 a.m. to 2 p.m. on Sept. 10 at the Haven Plaza Farmers’ Market. The entire CUIMC community and our neighbors are encouraged to stop by.

Speaker: Samuli Siltanen, University of Helsinki

Title: CT scans without X-rays: parallel-beam imaging from nonlinear current flows

Abstract: X-ray tomography (CT) and Electrical Impedance Tomography (EIT) are two fundamental inverse problems.

CT is based on recording X-ray data of the patient along several angles of view. Image reconstruction is geometrically straightforward, linear, and only mildly ill-posed. However, as a downside the patient is exposed to ionising radiation.

In EIT, the patient is probed with harmless electric currents, and the resulting voltages are measured. The mathematical model of EIT is the inverse conductivity problem [Calderón 1980]. The currents travel along curved paths, determined by the unknown conductivity distribution, so image reconstruction in EIT is nonlinear. Moreover, EIT is very ill-posed, demanding a high level of regularization against measurement noise and modelling errors.

A fundamental connection between EIT and CT was found in [Greenleaf et al. 2018] by using microlocal analysis. There, it was shown that a one-dimensional Fourier transform applied to the spectral parameter of Complex Geometric Optics (CGO) solutions produces virtual X-ray projections, enabling a novel filtered back-projection type nonlinear reconstruction algorithm for EIT. Note that there are no actual X-rays; the measurements are current-to-voltage data collected with electrodes.

The above analysis paves the way for a novel decomposition of the EIT inverse problem. It turns out that all ill-posedness of EIT can be confined into two linear steps in the decomposition. The other one is classical Radon inversion of parallel-beam CT and thus only mildly ill-posed. The other is a collection of one-dimensional deconvolutions with a known Gaussian kernel (a third fundamental inverse problems appears!), which is highly ill-posed. The new approach to EIT, called Virtual Hybrid Parallel Tomography (VHPT), offers unprecedented reconstruction strategies for EIT, including maximally interpretable ways of including machine learning to sub-problems.

Bio: I am a Finnish mathematician mainly interested in inverse problems of medical imaging. My favorite math topics are Electrical Impedance Tomography and X-ray tomography. I am passionate about popularization of science, publishing videos on two YouTube channels: Professor Sam and Samun tiedekanava. I work as Professor of Industrial Mathematics at the Department of Mathematics and Statistics of University of Helsinki and as team leader in the Finnish Center of Excellence in Inverse Problems Research. Also, I serve as Vice Dean at the UH Faculty of Science and Treasurer of European Mathematical Society.

This talk will be offered in a hybrid format. If you wish to participate remotely, please send an email to cr2090@columbia.edu.

A Talk by Laure Astourian

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Laure Astourian will present  The Ethnographic Optic: Jean Rouch, Chris Marker, Alain Resnais, and the Turn Inward in 1960s French Cinema (Indiana University Press, June 2024). The Ethnographic Optic explores the significant ties between colonial ethnography and innovative works of 1960s French cinema. Astourian probes the emergence of a self-aware urban French ethnography in both fictional and documentary films during the era of decolonization and offers fresh readings of canonical films including Moi, un Noir (Jean Rouch, 1958), La jetée (Chris Marker, 1962), and Muriel ou le Temps d’un retour (Alain Resnais, 1963).

Laure Astourian is Associate Professor of French at Bentley University. She earned her Ph.D. from the Department of French at Columbia University in 2016. Astourian was a 2020 Fulbright Research Scholar at the École Normale Supérieure (Ulm) and a 2023 resident fellow at the Mucem and Institute for Advanced Study at Aix-Marseille University (Iméra). She is the author of The Ethnographic Optic: Jean Rouch, Chris Marker, Alain Resnais, and the Turn Inward in 1960s French Cinema (Indiana University Press, 2024).

Medicine Grand Rounds @VP&S Amphitheatre 1

Ewig Award Lecture

Transthyretin Cardiac Amyloidosis: An Exemplar of Precision Cardiology

• 11:30am: Lunch provided (or bring your own!)
• 12:00pm: Lecture

To register and obtain a Zoom link, please visit eventleaf.com/e/MedicineGrandRounds

Click to register

In 1900, few had heard of Gregor Mendel. Ten years later, he was famous as the father of genetics. Even today, Mendelian ideas serve as a standard entry point for learning about genes. The message students receive is plain: the twenty-first century owes an enlightened understanding of how biological inheritance really works to the persistence of an intellectual inheritance that traces back to Mendel’s garden.

Gregory Radick will discuss his latest book, Disputed Inheritance, which turns the inherited narrative on its head. Radick attributes Mendelism not to Mendel’s own work, but to the outcome of a ferocious debate between two English biologists in the early 20th century. On one side was William Bateson, who, in Mendel’s name, wanted biology and society reorganized around the recognition that heredity is destiny. On the other was W. F. R. Weldon, who thought Bateson’s “Mendelism” pushed knowledge of the modifying role of environments to the margins.

Weldon died before he could finish a book detailing his alternative vision. Had Weldon lived, Radick argues, we might still talk of “genes,” but without the deterministic notion that the presence of a particular DNA variant is sufficient to determine if someone is born to be aggressive, alcoholic, blue-eyed, doomed to breast cancer, or crave caffeine. Instead, our gene talk would be routinely hedged with talk of internal and external contexts, because a gene would be seen as something with variable effects depending on the mix of other causes in play.

Event Speaker

Gregory Radick, Professor of History and Philosophy of Science at the University of Leeds

Event Information

Free and open to the public; registration required. Contact scienceandsociety@columbia.edu or historyofscience@nyu.edu for questions.

This event is part of the New York History of Science Lecture Series.

Sponsoring Organizations:

• Columbia University in the City of New York
• NYU Gallatin School of Individualized Study
• The Graduate Center, City University of New York
• The New York Academy of Medicine
• The New York Academy of Sciences