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Interview of John K. Delaney by David Zierler on February 2, 2021,
Niels Bohr Library & Archives, American Institute of Physics,
College Park, MD USA,
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Interview with John K. Delaney, Senior Imaging Scientist at the National Gallery of Art. He discusses the datasets he has been analyzing during the pandemic, and he recounts his childhood in Boston. Delaney describes his experience at Rockefeller University and his interest in phototherapies and measuring porphyrins under the direction of Dave Mauzerall. He discusses his postdoctoral research at the University of Arizona to study rhodopsin molecules and following the changes in protein structure after excitation by light. Delaney describes his interests in biophysics and his subsequent postdoctoral position at Johns Hopkins as an NIH fellow working in the lab of Sriram Subramaniam, before taking a job in industry as an optical engineer. He explains the circumstances of his initial involvement at the National Gallery of Art and the Gallery’s realization of the value of spectroscopy for analysis and preservation of paintings. Delaney describes how he built an expertise on hyperspectral imaging. He explains why the Gallery supported this work and how a global community developed for this field. He explains the value of his work for art authentication and the opportunities he has pursued in public outreach. At the end of the interview, Delaney explains some of the key physics concepts that inform his work, and he describes his ambition to write a book on reflectance imaging spectroscopy of paintings.
OK. This is David Zierler, oral historian for the American Institute of Physics. It is February 2nd, 2021. I’m delighted to be here with Dr. John K. Delaney. John, it’s great to see you. Thank you for joining me.
Alright. So, to start would you please tell me your title and institutional affiliation?
Of course. My title is senior imaging scientist at the National Gallery of Art in Washington, D.C.
And a very in the moment question. I’m curious, over these past ten months of the pandemic, obviously there’s a physicality to your job where there’s only so much that you can do over Zoom. So how have you been faring over these past ten months?
It has been a deep data analysis dive into a series of large spectral image datasets taken o paintings. So, what we did was just before we had to close the doors at the Gallery, my colleague and I collected a whole variety of spectral imaging modality datasets of the Gallery’s collection of Vermeer paintings. So, we have essentially four Vermeer paintings and two “fakes” and we collect the hyperspectral data on all of them. We’ve been processing all of those datasets in conjunction with an art historian and a conservator in order to come to sort of a definitive conclusions about his working methods.
So, basically, you’ve been able to do a lot of work remotely?
Yes. We got like one- a few days' notice that we were gonna close and I brought home our largest computer and there you go.
So, you really haven’t been to the museum since?
We did open up for a while for a small number of staff to do some work and we did collect the image data cubes on the Vermeer paintings. But otherwise, no. And it’s actually been a good time because it’s given us a very large block of time to analyze a lot of datasets.
Right. And this is probably something-
It’s kind of the perfect for remote sensing. You go get to collect a lot of data, then you spend most of a year analyzing and then you write some papers.
So, John, was this something that was on the backburner and this was a great opportunity to do it? Or did the timing really just work out and this is now being done quicker than it otherwise would have?
So, at any museum important paintings in the collection are hard to get to study. So, it was in this particular case, a rare opportunity where only part of the gallery was open to the public during the initial phase of COVID. And these paintings were off view. And so, we had an opportunity to spend time studying them. And that was actually a rare event and we took advantage of that. Both the curators, art historians, and the conservators, and ourselves. We said, “Okay. Let’s do it now. We’ll never get another chance.”
John, just to get a sense of the overall hierarchy at the National Gallery of Art, where do you fit in in the org chart? Who are the people that you report to and who reports to you?
My position is a little bit unique. I came into the Gallery as sort of an experiment unto itself. The Gallery has, like many museums, a conservation division whose primary mission is to conserve the works of art as well as to study them to support exhibitions. So, both for preservation and then for the art historical information. In conservation divisions there is a scientific research department, which are generally manned by chemists. Typically, analytical chemists with backgrounds in physical and organic chemistry. But over the years a few physicists have snuck in.
And a lot of the scientific methodologies that people have used have been point analysis methods done by taking microsamples that are only about a hundred micrometers in size. From these small samples they can get a wide range of information including stratigraphy of the paint layers, the pigments by polishing them into cross sections of the paint layer. What we are trying to do is to use noninvasive spectroscopic techniques that have been optimized in a variety of fields like Raman, diffuse reflecting spectroscopy, and x-ray induced fluorescence which provides element information. And turn them from spot measurements and into scanning measurements to make pigment maps that cover the entire painting. And that’s been the big focus of the field because when you take a microsample you can only work along an existing paint crack. You really don’t want to take it from a pristine area. So, you’re very limited where you can do your measurements. But if you can scan the whole artwork, then you get a better idea of the distribution artists materials such as pigments. You don’t miss things. And that can be a very valuable set of data as it helps guide you in choosing what sites to sample. You can say, “Go take the sample in this area to answer your question as opposed to somewhere else.” And it makes it a much more strategic analysis, I think. And you know, when people are doing remote sensing on the earth or in Mars, they’re looking for specific materials. But there is not always a spatial relationship between sites that are important. But in the painting of course, there is a lot important information about how pigments are distributed because there are spatial forms and shapes. And we can get at that information about that as well since we are using an imaging spectral modality.
And in terms of the hierarchy, who are the people that are working for you? And in terms of the taskings, how high up does it go in terms of the things that you’re directed to do?
As I’d mentioned earlier, so I was brought in because there was a realization that the field could take advantage of these sort of analytical digital imaging techniques. These sort of applied remote sensing techniques. So, I was brought in on an Andrew W. Mellon grant to essentially do research to develop and apply these techniques, develop protocols, modify instrumentation, and then train people. So, I’ve also been training Postdoctoral fellows. So, still we all ultimately report to different departments. I report to the head conservation scientist, Dr. Barbara Berri, and she reports up to the Chief of Conservation.
And what are the educational backgrounds of some of the fellows that you oversee?
They have either traditional PhD degree in chemistry or a PhD in Conservation Science, usually from prestigious institutions. The fellows we get from Europe typically are the ones who have a PhD in Conservation Science. Some of these fellows usually start looking for a postdoctoral experience in science before finding us. And generally, we’re working on applied chemistry, or applied physics problems so they get experience in a bit of both. We often publish in traditional scientific journals as well as conservation science journals. Usually the papers are the development of new spectral imaging technique with an application to a cultural heritage problem.
Well, John, let’s take it all the way back to the beginning. Let’s start first with your parents. Tell me a little bit about them and where they’re from.
Ah, yes. I am from the Boston area. My parents, my father is from Massachusetts. My mother’s family is from Maine. And I lived in a town called Weston where my father was a teacher of history in the middle school. And my mother was a nurse.
Where did your parents meet?
They met in junior high school. It was one of those things where they met in eighth or ninth grade and they stayed together ever since. My father was a football player and a very good scholar and came from a family with not much money. He basically grew up with his mother and grandparents who were immigrants from Italy. And he managed to get a scholarship to attend Brandeis to play football and study. And it worked out tremendously well for him.
John, growing up was Boston close enough for you where it was a part of your experience?
It was really close by. Weston is also next to Concord, Lexington. So, there was a lot of emphasis on literature and history about Henry David Thoreau, the Revolutionary War for Independence. You know, we had a lot focus on independent thinking in school which was a big part of the background I was exposed to, as well as poetry.
In terms of your educational trajectory, I assume that science was an interest for you all the way back to probably when you were a young kid?
Yeah, the Apollo program was going strong when I was quite young. And so, that caught my imagination. So, the moon, and astronomy became pretty important to me. And I think at age seven, to save enough money to buy a small telescope. The one I wanted, they didn’t have at the store anymore and my father shelled out the extra money to buy the next one up which was rather kind of him.
And just in terms of foreshadowing, what about art and the humanities? Were these interests for you as well as a kid?
When I was in high school, and later in college I studied quite a bit of history. In fact, I kinda ended up where my history professor, although I was a physics major- I minored in history- said you know, “You can go on and get a doctorate in history if you’d like.” So, it was kind of a fun position to be in. The thing that was a little quirky about me is I have dyslexia. And so, it was sort of a weird dynamic at that time period because it was early enough on where some teachers had skills to help with that and other teachers didn’t. And it was very interesting to survive English where you got an “A” for ideas and “F” for grammar and spelling. And then turn out to get an “A” in history because they would look beyond the spelling and the grammatical errors for the content. And for the sciences that never really seemed to be a problem.
So, it presented a very strange dynamic. The story that I think is most endearing to me was when I got to high school, I said I really want to study sciences with the intention to go on and get a BS degree in science. And then as a junior the guidance counselor said after looking at my PSAT scores, “I don’t think you’re gonna make it to a four-year college. I know you like optics. Why don’t you think about this two-year program that specializes in a technician’s degree in ceramics?” And I said, “You know what? I’m gonna ignore that person” (laughter).
You know, and that was just the way it is. And there are many people that fall into this sort of category. But the great thing is education has moved on and there are always opportunities.
So, between grades, your family’s financial capacity, your desire to stay relatively close to home, what kind of schools were in your purview for applying?
My first interest was in astronomy. But I actually spoke to a person who had practiced in the field. And he basically said, “There are no positions unless someone dies.” So, I said, “Okay. I’ve gotta drop my interest level down a notch.” So, I said, “Well, what if I build telescopes?” So, I put a lot of emphasis into studying optics. And I started looking for programs like University of Rochester and the Institute of Optics there with the intention of going that direction, but the school was too expensive for my family. I did get accepted with a good fellowship to Worcester Polytechnique Institute whose physics dept had several well-known applied optics professors, so I went there. That worked out very well for me and for my senior thesis project, I did an optics measurement. The absolute optical cross section measurement of a Raman mode in benzene.
You’re talking about a senior thesis for undergraduate?
Undergraduate. Yeah. And out of that I became aware of biophysics. And I said, “Hey. That might be kind of a fun mixture.” There’s a lot of optical problems of interest in the study of biological systems. So, and then my undergraduate advisor suggested I apply to Rockefeller University which is well known for its interdisciplinary research in the biosciences. In part because it was more of a European traditional mentoring program where they only accepted twenty students per year. There was no undergraduate program. There are about a hundred graduate students in total. And their faculty to student ratio was 2.5:1. And so, it provided a very nice learning environment. And I got accepted and decided to go to Rockefeller.
John, from undergraduate to the extent that you were exposed to the duality of theory and experimentation in physics, where did you lean and how did that affect the decisions you would come to make?
I decided that during my undergraduate studies although theory was interesting, I found building a telescope, assembling and doing the optical cross-section measurements on benzene fascinated by experiments and their relationship to theory, I saw myself as an experimentalist. but not one that was simply going to look for new discoveries unconnected with theory, but as an experimentalist that works at the interface between theory and measurements that test them.
Were there any undergraduate professors who were particularly important for your intellectual development?
Yeah. There were a few. There was a professor of physics who had a degree in, essentially in applied optics from the Delft Institute of Technology, NH. Prof. Adrian Walther who had a strong influence on me. He was a very bright mathematician, and physicist. A very funny guy with a dry sense of humor. Let’s see also, Professor Ed O’Neill, who was a big burly Irishman who did a lot of work early on statistical optics. He sort of contributed to many of the ideas what we often call Fourier Optics. He told me a delightful story about going to an optical science meeting where there were these lens designers who were very familiar with geometrical optics. And he had set up an optical Vander Lugt filter to do match filtering. A set up where you show you get a cross correlation spike only when there is a match between the input letter and the filter of the same letter. And he said he remembered the lens designers trying to sketch out geometrical optics diagrams that could explain this phenomenology. And Prof. Adrian Walther’s research focus was on eikonal functions. Which loosely is derived from was Maxwell’s equations in the limit where the wavelength goes to zero. They inform you about the limits of geometrical imaging, for example can you have a system that will provide good images two different planes with one system. They tell you what you theoretically can do to get optimal imaging system without knowing what the optical design looks like.
John, did you have any formative summer internships that exposed you to the world of perhaps industrial research or anything like that?
I did, while working at Itek Optical Systems which Prof. Walther gave me a letter of introduction. I essentially learned to do lens design and optical systems modeling. This was really an excellent experience in applied optics at very high level full of fascinating people who had studied with some of the world’s best applied optical physics professors.
Now you started graduate school straight after undergraduate or you took some time off?
No, I started straight off.
And was one of the things attractive about Rockefeller was given your interests even from this early period were very multidisciplinary that you had interests in all of these different areas? Was Rockefeller’s curriculum specifically geared to be responsive to that and so that you wouldn’t be tied so strongly to a particular department or field of study?
Yeah. It was very attractive for two reasons. One, they were lab based, rather than department based. So that you could choose among these various laboratories who had mixtures of things such as cell biology and, physics or electrical engineering. You had basically people with different expertise in areas running labs with various research projects. So, it became clear to me these labs were interdisciplinary. So, I could do a project with people in the hospital, but it actually involved measurements that were rooted in photophysics that were part of the biochemistry physical laboratory. So, yeah, it was quite attractive.
And essentially it was kind of a sink or swim environment at Rockefeller where you were thrown in as a graduate student but they kind of treated you like a postdoc. And it was a very research-intensive environment as a result. And graduate students came with money. I mean we had a certain, amount of money for research. So, we were worth collecting. And well, as you know young students can be motivated to do great things.
And the other cool thing about when I went there a paper had just been published by one of the labs that I was interested in. They had made a molecule that was an analog for the photosynthetic reaction center. It was a porphyrin quinone complex, where porphyrin could donate an electron to the quinone after being excited by a photon. And they were trying to see whether the electron travelling through space between these two molecules by quantum mechanical tunneling (nonadiabatic process), which was one idea that was kicking around for the mechanism of electron transfer in the photosynthetic reaction center. Or was it by an adiabatic electron-transfer method? And I thought, if you could study quantum mechanics and relate it to a key event in biology what could be more interesting than that to a young scientist? So, I said, “This would be really cool to study.” I ended up getting to work on that project when I was there. So that was fun (laughter).
Was the research culture at Rockefeller, was it more geared toward basic science or were there specific applications in mind in terms of commercial viability? In terms of patient outcome? In terms of thinking about patents?
Both. That’s a very good question. So, when I was there it was basic research. But in the hospital, they were solving problems related to diseases. So, I did some work in support of an alternate to phototherapy for jaundice where they were looking at a particular series of porphyrins that could competitively bind to a protein that breaks down bilirubin. And so, there’s sort of phototoxicity that could occur if porphyrins were used along with phototherapy. And the groups were working on the problem of trying to make porphyrins that would pose less of a risk by adding heavy atoms to reduce the excited state lifetimes. So, it was this odd thing where you’re talking about testing stuff on children dealt with a medical disease, jaundice. And there you’re still talking about quantum mechanics and how these molecules basically deactivate their excited states.
Given your interests in cell biology, biophysics, and working with the hospital people so much, did you ever flirt with the idea of pursuing an M.D.?
No (laughter). No. I had thought about- when I first got to Rockefeller, I really thought about well you know, optics, vision, the processing. I mean what’s going on in the brain. About how the scene is encoded. It’s extremely fascinating. And then I started to find out how these the type of experiments was done to get at the information. I was like I’m not interested in doing such studies on little creatures like that. It’s not for me (laughter).
John, given the fact that you were involved in so many different research endeavors, of course for a PhD thesis, you need to settle down and focus on something specific. So, my question is, did this-
Yes. And my advisor brought that up (laughter).
Right (laughter). Well, that’s exactly my question. Do you decide what you want to focus on and then pursue a relationship with an advisor? Or do you have an advisor that can take you in any number of directions? And based on that mentor/mentee relationship, that’s how you narrow down your interests?
So, what I started doing in Rockefeller was starting to learn how to do measurements. Measure the excited state lifetimes of molecules. Particularly of porphyrins. And looking at electron-transfer reactions between molecules and the theories about the possible mechanisms by which these reactions could occur. And there was another instrument that a former graduate student built which was a state-of-the-art transient absorbance spectrometer allows you to follow the kinetics electron transfer reactions by changes in absorption of molecules when they gain or lost an electron. And we studied that these electron transfer reactions as function of temperature or solvent dielectric to try to figure out the mechanism.
So, I was learning how to use that that instrument. Taking it on. And this project for medicine came out of the blue. Someone, basically my thesis advisor, said, “Hey measure these excited state properties of these porphyrins. They’re trying reduce the excited state lifetime and I have selected a few that should work.” So, I started doing it. And that got very successful and then the hospital physicians and scientists said, “Why don’t you do your PhD, in part with us at the hospital on these alternative porphyrins for treating jaundice. And I remember my thesis advisor coming in out of the blue one day in the lab I had my desk in one evening saying, “Your PhD thesis is on electron transfer reactions involving porphyrins and not modified porphyrins for treating jaundice. You need to focus on that.” I was like, “Okay” (laughter).
I wasn’t as far away from one topic as it sounds.
Who was your thesis advisor?
Prof. David Mauzerall, head of the lab of photobiology at Rockefeller
And what was Mauzerall working on at that time? What was his area of research?
What Dave Mauzerall was very keen on was trying from an experimental point to understand the mechanism of electron-transfer in the photosynthetic reaction center as well as other charge transfer reactions which occurred in biology, such as across cellular membranes. Because of this he did a lot of very interesting work on the early steps in early photosynthesis and steps in the evolution of photosynthesis. He was a very creative scientist. He would design new experiments and go in the lab, do them by himself. He would then come out with a paper on the work and use results to get a grant and then hire a postdoc to work on it. It was just, by then, many other labs had to turn to a different operation where the head professor was focused on raising fund, developing ideas, and writing papers but was no longer working in the lab at the bench doing work.
John, given between your advisor and the hospital that you were kind of being pulled in two directions, for better or worse, how did that play into what your PhD thesis actually was?
It did play into it in a sense that it was a chapter. My thesis was in the end a series of papers that covered the work elucidating the mechanism of electron transfer in a model system for the photosynthetic reaction center as well as the work with the hospital.
Given how closely you were following trends in the field at this point, I’m curious if there were any advances either on the theoretical side or the experimental/observational side in technology that were particularly useful for your research?
Well, it was a time period where people were moving rapidly from sort of low-grade nanosecond pulsed lasers to tens of picoseconds. We had a nitrogen laser that basically fed a homemade dye laser which had about ten nanosecond pulses which was enough to follow the kinetics of the reaction from the triplet states using transient absorption. We were looking at electron-transfer from the triplet state of the porphyrin occurring with a lifetime of one hundred and fifty nanoseconds. But the electron reaction from the singlet state was going in half a nanosecond. So, then the picosecond lasers were big change for our experimental measurements in that it allowed us to follow the faster reactions.
I’ll test your memory. Who was on your thesis committee?
Ah! There was Henry Linschitz who was on my committee. Henry Linschitz was a professor of chemistry at Brandeis and had done worked important work in photophysics and photochemistry. I want to say I remember he was also involved in the Manhattan Project and he did some early work on the triplet states of porphyrins. And he had a gazillion stories. And I think the most awesome experience I had was when we were writing our first big paper to go to the Journal of the American Chemical Society on electron transfer. At eleven o’clock at night, these two giants (Dave Mauzerall and Henry Linschitz) were arguing emotionally, intensely about what the results allowed one to conclude about the mechanism of electron transfer. Politely, but arguing! About what you can and can’t say. What this experiment says, what this doesn’t. And that’s when I realized the level of passion in science at this level was serious. And it was really cool.
John, of course, then in oral defense there’s a range from you really having to advocate that your research is significant, and you belong as a member of the club. And all the way on the other side where what you’re doing is so cutting edge, you’re more or less cluing in your advisors on what you’ve been doing because they’re interested in learning from it. Where in your memory do you see yourself falling in that spectrum?
I wrote a few chapter sections that talked about theories of electron transfer and some modeling we did that looked at the role of the external solvent—so we had electron-transfer going between the porphyrin and the quinone which were held in a complex. But the porphyrin quinone complex was molecule that had big, bulky, bridging arms. So, it effectively had its own dielectric constant which sort of dominated. And although you could get a few molecules from the solvent inside the porphyrin quinone complex, the outside environment (solvent) is essentially the thing that changed.
So, Dave Mauzerall developed the idea to looked at the role of the electron density of the solvent outside on the rate of the electron transfer. And then we did some modeling to see if you could show that by increasing electron density outside, you could squeeze the wave functions associated with the electron transfer between the porphyrin and quinone, increase the overlap, and thus increase the rate. So, I prepared for that type material for the thesis defense! You know, I always figured we’re gonna talk a lot about theory of electron transfer and what the results I got showed. And then I ended up, and they wanted to talk about basic stuff (laughter). You know like, what’s the structure of chlorophyll? And off into all these broad general directions that like, oh my God. I didn’t quite prepare for that (laughter). So, it was an interesting experience where when you do your thesis you focus so much in exactly on the details that it’s important to step back to realize the people reviewing you aren’t looking that deep into things.
And I think that was my big experience coming out of that. It’s kind of funny.
As you were thinking about postdocs, as you were thinking about a long-term career, just in terms of your identity. The kind of niche you might fill in a faculty position or in an industry type research area. What would you call yourself?
Well, when I started, although I had experience working in industry in the optics field and thought that was really cool, I wanted to stay in the biophysical community doing research. And so, I looked for postdoc and then eventually tried to look for faculty positions in that area. So, I tried to stay in the area of spectroscopy and especially time resolved. I was interested in learning about vibrational spectroscopy and there became an opportunity to look at rhodopsin molecules and follow the changes of the protein structure after excitation by light.
And so, I went into that direction for my postdocs. For my first postdoc I was working at University of Arizona in a lab that did picosecond time resolved Raman. And they could actually follow the isomerization of retinal either in rhodopsin or in bacterial rhodopsin. So, we did a lot of work on that with retinal analogs which were designed to alter the flexibility of the molecule to see how it affected the early events after absorbing a photon of light. I did that for a couple years. And then mutations of bacteria rhodopsin, mutants where the specific amino acids around the binding pocket of the retinal molecule were being change were coming along. Bacterial rhodopsin is transmembrane protein that they could synthesize with amino acid substitutions and then reconstruct or refold the protein to make it active. And so, I read that you basically could make use of mutants to slow down the photon induce reactions to the point where you didn’t need fast lasers to follow some of the important changes in the photocycle. You could do it at room temperature using microsecond resolution.
So, at the Johns Hopkins School of Medicine where I did a second postdoc, I studied these mutants of bacteria rhodopsin with some of the same retinal analogs from first postdoc in Arizona. And we did very well. We got a several papers. So, that was a very productive time. We started to also look at coupling between the retinal molecule and the protein and how this interaction played a role in changing the 3-D shape of protein. At the time rhodopsin proteins were used as model systems for a single transduction which are important in biology and medicine. It was kind of an exciting time to be in a biochemistry lab and in a department where people were doing genetics, biochemistry, as a physicist doing these more analytical measurements.
John, just to stay on The University of Arizona for a minute, what’s the history of the George Atkinson Laboratory? And what is its overall mission would you say?
So, the Atkinson Lab was in the Chemistry Department although it was tied with the Optical Science Center as well since they were developing new lasers and forms of lasers spectroscopy- which was pretty cool. The lab did a lot of early measurements involving time resolved Raman try to get at transient Raman signals of intermediates during the long photo induced reaction pathway involving the isomerization of retinal molecule in the binding pocket of rhodopsin protein. And that was to me it was pretty cool because my PhD thesis had been looking at electronic transitions. You know for these charge-transfer states there are molecular vibrations that contribute to electron transfer process. And so, I saw the opportunity of doing some vibrational measurements to see if you could see which vibrational modes that were coupled to the electron-transfer event.
Was this a clearinghouse for professors? For visitors? Would you meet a lot of people from outside The University of Arizona research community?
Yeah! There was a lot of research going in Europe in the rhodopsin protein field, especially in the UK and in Germany. Bacterial rhodopsin became one of the first rhodopsin proteins that whose 3-D structure was determined by cryo-EM (diffraction) microscopy. Which was really cool. They had sequenced it. They could easily make mutants. They could fold it. It was just a dream for people to do studies on. And so, there was a lot of exchange with the international scientists with the lab. I got to go to my first international meeting that way from those exchanges.
Where did the optical science center fit into the grand scheme of things at the university?
In this lab here, we had some PhD students that came across for their thesis work on Coherent Anti-Stokes Raman Spectroscopy which was a big area of activity in the lab. There was some shared lectures and stuff. But not as much as I kind of expected to occur unfortunately.
Who were some of your key collaborators during your time at Arizona?
Prof Mordechai Sheves of the Weizmann Institute of Science, who supplied a series of modified retinal molecules, i.e retinal analog molecules. There’s a key isomerization event which initiates the photocycle that involves the rotation of the polyene chain around one of the double bonds which seems to occur between the excited state and the ground state transition. He basically put a blocking ring around that double bond to prevent the isomerization. And we substituted that retinal back into the bacterial rhodopsin protein. And then we followed its kinetics and intermediates in the photocycle. And what we found out is the first intermediate (labeled J) in the bacteria rhodopsin photocycle with the normal retinal (which was characterized by a redshift in its absorption) also occurred with the Sheve’s analog retinal that blocks the isomerization. And there was a lot of debate at that time period what this could mean for the mechanisms of how the isomerization occurs of retinal in rhodopsin’s. Was the isomerization occurring in the excited state, or during the transition to the ground state, or when the retinal was vibrational hot on the ground state surface.
Mordechai Sheves made a variety of these sort of analogs and I continued to study them in the mutants of bacteria rhodopsin during my second postdoc at Johns Hopkins School of Medicine in the Sriram Subramaniam lab. And there we found evidence that the protein and retinal needed to push on each other during the reisomerization in the ground state at the end of the photocycle. So, we found evidence for physical coupling between the retinal and the protein of motion between the two. And that was kind of neat.
John, as you noted, being a postdoc—
I go into way too much detail! I apologize.
No (laughter). It’s what it’s about. Given that the postdoc time, as you noted, is a time really to publish a lot. To give a sense of the broader academic communities that you were a part of, conferences is a great way to get a window into that. What were the key conferences in terms of both you conveying to your colleagues in the broader world what it was that you were learning and where you wanted to go to just stay on top of what some of your colleagues and peers were doing at the time?
There was the yearly Biophysical Society meeting s and then there was a regular conference on Retinal Proteins both of which I attended on occasions. The conference on Retinal Proteins was interesting because you would meet people that were looking at the cell biology of the whole organism, bacteria rhodopsin. People like us looking at the spectroscopy of the intermediate events in the photocycle. People making mutants of the bacteria rhodopsin protein and refolding them which a group at MIT was heavily involved in. There were the people doing the 3D structure work I think at Cambridge University, Richard Henderson’s group who along with two other scientists won the Noble Prize for developing methods that allowed determining the structure of the bacteria rhodopsin protein using cryo-EM. And so, that was a place to be. Because you saw very senior scientists and then you saw postdocs and graduate students and you had opportunities to chat with them all. It was sort of like a Gordon Conference, in a way.
Now did you specifically want to do another postdoc? Was that necessary for you, intellectually?
The fast spectroscopy was good and important. But I began to realize that the field was changing fast. And this working with mutants of proteins and working with analogs of retinal and having more experience with the biology would be invaluable for me. And the opportunity to be at Johns Hopkins School of Medicine in the biochemistry department, Lehninger’s old department, would be a tremendous growth opportunity. And I did have the opportunity to get a NIH (National Institute of Health) fellowship for those three years to work in Prof. Sriram Subramaniam’s lab. So, I saw it as a way to sort of round out my experience so as not just be a just a laser jock working on biomolecules.
And you know, towards the end of that time period in the early-nineties, science suffered a significant decrease in funding for a variety of reasons. And people really started to worry about how am I gonna get a job in academics? I had colleague of mine who did a lot of important DNA sequencing at Rockefeller for his PhD. You know, they were molecular biologists. They were from the best labs, went to the best graduate, best postdoctoral programs. And they were applying for a hundred jobs and would get two interviews and one offer. And so, when I started applying for jobs at the end of five years postdoc where you know, I had done my thing where I got out my two papers every year. Good papers you know and got a really good name for myself. When I saw my Senior scientists not getting their NIF or NSF grants renewed in the field whose work focused on time revolved spectroscopy of biomolecules, it was like whoa. Things are really changing.
And also when I applied for faculty positions I kind of ran into this game where departments would do with someone with a background in physics and biology. Biophysics was still new. And I remember one faculty selection committee was debating whether I was a physical biologist or a biological physicist. And that mattered to the faculty research committee in order for them to make a decision about whether to hire me or not. I’m going like, uh, maybe it’s time to go to industry. So that’s why I went off to industry.
John, just so I understand. You were physically at Hopkins, but you were funded by NIH?
What kind of, besides being funded by NIH, what kind of interaction did you have with the National Institute?
There really wasn’t. When we had to send a yearly report in, they didn’t come and check up on us. And they didn’t do, as I recall, they didn’t invite us down to the NIH campus. So, there was not a lot. You know, we certainly worked with enough people who were funded by the NIH on that problem. I always thought it was sort of weird that the researchers on NIH campus were not involved much with the funded NIH fellows, they were just another series of researchers from a different institution.
Academically, intellectually, did you see your years at Hopkins as a continuation or a departure mostly from what you were doing in Arizona?
No. An absolute continuation. It was a way to do the same sort of experiments, answering, looking at the same set of questions, but using mutants. And with much simpler technology. Much lower cost technology because of the mutants were slowing down the timescale, to get at answers to some of the same questions. So, I saw it as being a logical extension to use new tools that were becoming available. The ability to manipulate the molecules and proteins. People were chasing faster and faster time resolution in order to try to answer structural changes in the protein. So, you had labs move to femtosecond lasers from picosecond lasers. Which meant huge grants for the instrumentation. But you could get at some of the same problems by just working with a good molecular biologist who could synthesize the appropriate mutants. And then use much less expensive equipment to get at them. And so, I saw it as being like the smart thing to do as a future faculty member. You know, I kind of always thought the most important thing to do was adopt your experimental strategy for your problem that you know, with the tools that you had handy. And I didn’t see myself trying to, literally hire postdocs to build new lasers.
Were you drawing different conclusions based on the different techniques? Or were you refining and improving the same conclusions that you were making in Arizona?
I think it was both. So, as you go to faster and faster timescales to follow very quick reactions, things aren’t moving in the protein. But if you’re looking at reactions on the slower timescale, you’re you know, looking at timescale where the protein can readjust. And that became much more interesting because now the protein was dynamic. And of course, when you think about a lot of reactions that are going on at the cellular level, things are in motion. So, the problems we looked at Hopkins were in a way more important to the biology field.
Who were some of the key people you worked with at Hopkins?
Sriram Subramaniam who was running our lab. He went off to NIH and ran a large center on using cryo-electron microscopy to get of 3D structures of proteins. (Phone Ringing)- Excuse me. But there were a lot of work being done in other laboratories in the department. And what was really cool about that department unlike Arizona was they had seminars. They had basically weekly seminars for graduate students and postdocs would have to review a paper, a journal club. And then there would be meetings where different departments would students give presentations about the research. Everybody in their group would give about a ten-minute talk on what they were doing. And so, there was a lot of exchange of ideas. The journal club was pretty hilarious because that’s how I met my wife. It was at one of the journal clubs. I had to give review of a paper at journal club to a bunch of very bright biochemists, some geneticists. And I was going into as a physicist with experience with biophysics. It’s like what the hell am I gonna talk about? So, I decided to talk about photoacoustic and listening to plants as a way to look at the change in entropy and energy within the plant during the photosynthesis cycle. And you could actually hear the bursts of oxygen being released. The papers were from my PhD thesis advisor, Dave Mauzerall did, and it made for a pretty good story. My wife came to the meeting looking for someone to date apparently. But that was another story.
John, given that you were reading the writing on the wall in terms of how bleak the academic job market was, did you bother at all? Did you sort of put your antenna out for faculty appointments? Or at that point-
Yeah. I did. I did apply and had people write letters and they were disappointed nothing turned up. I think that the challenge was just how I fit into a department. I mean, the issue at that point was departments were still pretty traditional. And my background was between physics and biology.
And chemistry, for that matter.
Yeah. And so, there were just a lot of departments that weren’t sure how they saw me because they were doing more traditional work.
It does beg the question at this point how you saw yourself. In other words, when faculty hiring committees are thinking what’s this guy going to teach or what thesis is he going to oversee? How would you answer that in your mind as you were conceptualizing an academic career?
Well, I didn’t see a problem because I thought interdisciplinary research was the future. I saw breaking down barriers was critical to getting new grants. I saw it as the way that I’d been doing, learning to do science at all these institutions. I thought all these guys were just in the past. So, I think I was a little, I was surprised, quite frankly. But I could appreciate their problem because my projects included some physics, and then some stuff that sounded like a biology that they didn’t know. But of course, all this has changed now. This is now recommended. There are a lot of institutes set up on campuses where faculty are actually shuttled between working between the two of them.
It’s funny because as a product of Rockefeller, that model still seems to be really unique in the emphasis on interdisciplinary research.
I think so. I think it was the best because you’re usually working alongside a very senior scientist. And you’re kinda learning how you know- one of the things that I was always amazed by my thesis advisor, is he didn’t do a lot of wasted experiments. He spent a lot of time thinking about what the right sort of experiments are to do. What am I trying to answer? And I thought that learning that model was very important because one of the things you can argue in some labs, some students get trapped in trying so many things. And a lot of them don’t work out. And it’s not a very efficient way to do science unless you have a lot of people. And for some labs, some problems, it’s the only way you can do it. But when you have a little bit of theory and you’re designing your model systems then you can take advantage of a more strategic approach.
As you set your sights on industry, were you thinking more- I mean, again this is after Bell Labs. This is after sort of the golden era of you know, pure basic research.
Exactly. The same sort of thing. I did look around a bit for the type of projects that were in sort of in the biophysics area. But they weren’t very sophisticated. They were interesting but they were looking for devices and products for a medical diagnostic problem. And I did consult with one group. And they had really hard problems, but I was gonna be working on a detection system that was going to require a lot of effort to see if you could make work. And that didn’t sound exciting to me.
So, I ended up working with a group of people that I knew from the past who were building very sophisticated optical imaging cameras. And there were very large number of engineers and scientists working on them. A traditional, but complicated aerospace problem. They were designing and constructing very acuity multispectral cameras that needed to have high optical-mechanical stability. Very good optics. Novel ways of image processing that highlighted how the spectral information of objects changes from spectral band to band. And that was a challenging applied optics problem involving spectroscopy which I knew. But also involving optics, which I knew something about too. And a lot of it, in some engineering areas which I didn’t know.
So that became sort of like interesting to me and the group that I joined did a lot of the systems modeling which I liked. You did end to end system performance modeling of the complete camera in operation. And I kind of liked the idea that you could model the optical performance of a system before you built it and predict its performance literally when it’s all aligned to the ninety-five percent level. That was pretty cool.
What was your initial job title?
Uh, I was an optical systems engineer. I did lens design too. I designed some optical design for thermal IR channels of cameras that fly on jets. These things were kinda cool because you had to design them. Then they would build them and then they would put it all together and they’d fly and test it. But you know, it wasn’t like, oh, it didn’t work too well. Let’s take it all apart and do it again. No, you had to be right. You know, I used to joke with people I interviewed people for positions in systems engineering group that I managed. I said, “You know in school when you get like an eighty-five percent right on an exam, you’re doing good.” I said, “Eighty-five percent doesn’t cut it here. The company loses money. You gotta be like at the ninety-five percent level all the time.” So, you know, it’s a different way of doing it.
But what you had was this incredible ability to do all this modeling. And so, some of the managers would joke you’d spend all day building these mathematical models. We used to use Mathcad or MATHLAB to do this. And they saw us, and they thought we were just playing and having fun because we would write you know, ten pages of script to model the performance of something and we were really excited when it worked. And the people that were doing this modeling work had PhDs in astronomy or mathematics and others had degrees in optics and electrical engineering. So, it was a pretty fun group.
Coming from academia, having academic sensibilities, what were some concerns that you had coming into an industrial research environment? And to what extent were those concerns confirmed or not as you got comfortable?
No, that’s certainly true because you bump into some of the wall’s companies have to set up to keep people focused on the business but one of the things that was really fun about being in industry was the team environment. You were working on a hard problem and you know, the end user was important. You really wanted to succeed. So that was great. People would go the extra mile. And you met people that had just innate, inborn ability to do complex design even though they were not highly academically trained. But they were revered. I mean guys who could polish glass or align an optical system. They just knew how to do it. And they didn’t have a PhD And then you’d run into people who had classic academic trainings who would say, “I’m not an engineer,” but a physicist etc. But who were kind of doing engineering work. And there was a lot of old- because this company came out of a group that was set up by a bunch of physicists from Boston University, terminology you would associate with academic departments. And people were still encouraged to go to optical meetings to learn about stuff, to stay at the cutting edge. And also read papers. So, there was enough of an academic environment to feel that, but it was not like working in an academic research lab or a Bell Labs.
John, working in private industry, it’s a very different budgetary environment. I wonder if you can talk about any pressures you might have felt or expectations to tie your research to a bottom line? Or not, as it were?
So, as time went on the things did shift in all of industry. In the past, if you think about as you said earlier like Bell Labs, they had a fair amount of research money and I’ve met scientists that came out of its environment. Where you couldn’t see any difference between the work they were doing there and what was being done in universities. In the companies I have worked in there was an ever-increasing tie between funds available to explore new ideas how those ideas were tied to real products.
Well, it’s nice when you have a monopoly, of course (laughter).
Yeah, yeah. Of course. Yeah (laugher). And I have read papers from Bell Labs on electron-transfer on cadmium sulfide. It’s actually what I would now call a cadmium pigment and where the focus in art conservation science is understanding degradation pathways. And they at Bell Labs were interested in its properties as a semiconductor.
At companies, that type of more basic research money went away. And then everything got tied closer and closer to a product. So, you’d only do research and development if it was directly tied to going after a program to develop a new product. And that was frustrating because it’s like how do you invent the new thing that makes you unique in your business if you don’t have time and money to do that? Because you’re only trying to react to what’s in front of you right now. And that, I think it’s a challenge for everybody to try to figure that one out now.
Coming from so many different academic research environments, how would you compare the quality of the instrumentation you were working with in this private industry area?
It was first rate. The quality was pretty high. Compared to academics, it’s highly variable depending upon which lab. I mean I was fortunate to work at and study at some of the best institutions in the U.S. and the science areas I was working at. And they didn’t lack for really good equipment. But other institutions don’t have that. And when you went to Europe you were more acutely aware of the instrumentations they did or did not have in those laboratories. And I think that sort of capitalization of science through the grant process is hard.
Yeah. In private industry of course, the name of the game is making deliverable products that would-be clients want to buy. So, I wonder if you can talk a little bit about how your research, your engineering work really contributed to that overall goal?
Well, you know a lot of this comes down to systems engineering, an area that I think is very important. It’s an interdisciplinary because you need to know a lot of the different technology areas. Ultimately one of the things that systems engineers do is to take the vague set of requirements form a customer, i e. I want to be able to see these things under these conditions. And from that you have to start developing an overall systems design with flow-down requirements and design concepts for the other engineering teams to work from. Often you might try to leverage what you have. Your in-house skills. The flow down requirements help guide the work of the other engineers in design, building and testing the final product to ensure it meets the goals of the customer. The other task is doing end to end systems modeling to validate as much as possible the instrument will work as designed and under the conditions expected,
As you were gaining seniority in the company, did you move on into administrative responsibilities?
Yes, I did some managing other scientists and engineers. But that wasn’t a major activity. I mean basically these people were motivated. They did their work well. There was some overseeing some budget work to the management work. One of the great things about companies is that they had people who worry about budgets, worked on this issue so you were aware of them. They were sort of an independent group. One of the things I’ve noticed in other settings is that sort of responsibility to that, worrying about costs and stuff like that, doesn’t exist and probably should be there to better see. So, that freed up a lot of time to still stay on the technology side.
And I think that in system engineering a lot of your work relates also to business development. So, you’re working with business development people trying to provide the technical background for that. So, it wasn’t that bad. I think that what I really liked in industry was I kind of had a problem with the academic structure because I thought graduate students and postdocs weren’t paid at the level of the work that they were doing. Because they were often being asked to do more than it was required for their thesis. And postdocs were doing five to seven-year shifts. That’s a long time. And they were not being paid well. And there wasn’t a lot of job security. And I think that what I saw going on in industry is people were being paid more appropriately. And I really liked that. I never felt like anyone was not being respected professionally and treated financially well for their work.
Did you try self-consciously to keep up with academic literature? To keep your muscle memory in case you wanted to go back into academia?
Yeah. I did that in a sense. For example, in graduate school I had a colleague of mine who had a friend at the National Gallery of Art who is a conservator and she was mucking around with what they described was an infrared vidicon tube to try to look for underdrawing in paintings. By the working in the infrared they could defeat the Mie scattering of the pigment particles and any electronic absorbance and see preparatory sketches done by the artist on a white ground layer. And they were having an awful time with their vidicon tube. It was drifting all over the place and it wasn’t working. And he asked me, “Hey, you know anything about imaging in the infrared?” I said, “Yeah. I have some experience.” And I started going off and looking to see what these guys were doing and realized the technology had moved on. These vidicon tubes were great in the seventies and eighties, but now we’re in the nineties. And platinum silicide cameras were coming around for industrial thermal imaging.
And so, I started collaborating with the National Gallery of Art and in the process of doing this, based on the spectroscopy background I realized oh, people are doing multispectral imaging in NASA. And looking at the Earth. Well, we could look for minerals in paintings the same way. So, I kinda kept this sort of consulting for the Gallery. And then we would occasionally be publishing papers on the work. And I also started studying light scattering from the air/varnishes interface of paintings to help answer questions why some varnishes performed better visually than others.
The development of stable varnishes or resins for coating paintings was the key research area of the head of the science department at the Gallery during this time, Dr. Rene de la Rie. He was an interest to know why low molecular weight varnishes gave paintings a better visual appearance than high molecular weight varnishes. They didn’t have a theory for that but some clues. So, I said, “Okay. Let’s turn this into a surface roughness measurement. What do we do in optics to look at the roughness of mirrors?” And applied the same optical physics and lo and behold we got an answer of how MW of the vanishes effects the degree of leveling of surface roughness. And then we talked to people in the paint industry and they said, “Yeah! That makes perfect sense why you’re seeing these results that you’re modeling predicts it.” So, I just kept consulting and my company was nice enough to get me to play around with that. That said I was not reading as nearly much as I did when in doing academic research.
John, I was waiting to hear for it. The intellectual kernel that explains how the opportunity at the Gallery came up.
So, that’s what happened. I just kept helping different museums with the infrared cameras and began to realize that we could do something using reflectance multispectral imaging to identify artist materials. We did some sort of pilot studies. And then we started, talking to scientists at universities who were doing diffuse reflectance measurements of minerals which were used for pigments. And eventually [The National Gallery of Art] got a grant from the Andrew W. Mellon Foundation, which was already supporting conservation science and conservation at various museums, to bring in an imaging scientist into a museum setting specifically to adapt and develop digital imaging to help solve problems of interest in conservation and art history.
John, it’s such a great story because you so accidentally are just dipping your toe into this world and it doesn’t seem like there’s any specific goal in mind in terms of where this could go. So, the obvious question there is of course, museums have been around for a long time, spectroscopy has been around for a long time. But really what you’re doing, it’s uncharted territory. They’re interested in this because nobody has the expertise that you have and yet the need for the services that you’re providing surely predate your expertise and your services.
Yeah. What was happening was kind of two things were going at the same time. First, there was a strong interest in the museum to move away from film and to go to digital imaging for color photography of works of art. So, they wanted to take better and more color accurate images. The people that were responsible for taking photographs of paintings were really good photographers. To take a really good picture of a painting is nontrivial. You really have to think about how to properly light it. So, these were gifted photographers, but they were not technologists. They didn’t fully understand digital imaging technology and wanted help with this.
Secondly, several research groups were looking into spectral imaging as away non-invasively way to identify artist pigments and the Gallery wanted to pick up where we had left off some years back. All of this built on using a systems engineering approach to adapting and developing new digital imaging systems. This was the same approach we used when we had systems engineering modeling to determine what was the right spectral region to image in with an infrared a camera to visualize under-drawing in a painting? What were the requirements for a camera to work well? Then we did some preliminary experiments with a little point scanner that we built which had a single infrared Ge diode to and the painting conservators were kind enough to make simple test paint outs of various paintings made with traditional pigments covering underdrawings lines on a typical white ground. It was kind of fun, to work with the conservators to mechanically scan the test panels and compare the results from different spectral regions.
We did find the optimal spectral range (about 1.4 to 2.0 micrometers) and found the traditional vidicon infrared tubes used by conservators while sensitive to this region of the infrared did not have enough sensitive to get clear images of the drawing when covered by the thick paint layers found in most Italian Renaissance Paintings. At this time platinum silicide camera focal plane infrared arrays being developed for thermal imaging (~3 to 5 microns) did have sufficient sensitivity in the 1.5 to 2.0 micrometer region and Kodak eventually donated a research thermal imaging platinum silicide cameras after they did some- after my colleagues asking them to change the filter of one of their research cameras for a platinum silicide camera to operate where we thought it was optimal. They brought the camera down to the gallery and they were getting great, super-improved infrared images of the under-drawing.
One of the greatest images they had got with that camera was of under-drawing in Leonardo da Vinci’s painting of Ginevra de' Benci, which is in the collection at the National Gallery of Art. Which is a small portrait painting he did of a young woman. And what the infrared image showed taken with this new camera and filter underneath all the lead white of her face these little black dots outlining her eyes, lips and nose. By further into the infrared, the light scattering of the lead white was defeated revealing the drawing on the preparatory ground layer. And it became clear that he had transferred drawing of the woman on say parchment by pricking holes in it along the lines and transferring it over to the panel like a stencil. They had seen a few dots of these lines so what form them what was really cool to see the stencil technique. And to see it all in one image. And this ability to see these drawings in the Italian paintings where people for a long time were not seeing them because they were getting far enough into the infrared, kind of was like, “Hey, what this guy Delaney, these people know what they’re doing here. This is very helpful for us.” So, we did have a bit of a ground swelling within the community early on. And then to take it into multispectral imaging and then doing transformations, we spent a lot of time looking for hidden paintings. You know, earlier compositions that were painted over by Picasso during the Blue Period, which was a lot of fun.
John, was there a particular painting or a gallery or a collaborator that sparked this idea in you that you might have a major career change on your hands?
Or was it more of a gradual process?
No. It was pretty- well, two things factored into it. I mean being a spectroscopist at heart and while working in the industrial optics community on complex high acuity multispectral cameras was very satisfying, but the timescales to build up these large instruments, it takes time. And there are also limits to what the applied industrial fields are interested in. I became more interested in exploring spectral imaging, specifically hyperspectral imaging. I became very fascinated with the mathematics of the technique and what you could do optically with the camera. So, the museum did offer an opportunity to explore more what could be done with hyperspectral imaging more quickly on very challenging problems. And honestly to get back to a more academic research environment was a driver too. Because I saw the opportunity to do research and have postdoctoral students. So, such a combination was pretty exciting and attractive to me. The challenge, however, was it going to work? And the position was only for five years with no guarantee.
But why, John, of all places, of all institutions, right? I’m thinking like MoMA, The Met, Getty. Why of all institutions where you can focus your expertise, why the National Gallery?
Well, the National Gallery was particularly attractive because one, they were open to the idea. But more importantly within the science department they had a very good, diverse set of scientists: organic chemists, physical chemists, analytical chemists and even a plant biologist, all who knew artist materials on the microscale. And they had a very good connection with the curators and conservators. Because understanding a painting requires a lot of knowledge about how people paint, what’s the objective of the painting process the artist is developing? You really have people around to keep you grounded, otherwise you just come across as someone who is saying stuff, but it doesn’t relate to anything they’re interested in. So, I knew I needed to be in a place where I would make sure that I stay on track. That I’m solving useful problems. That was pretty critical. So, the gallery in particular offered that opportunity.
Meaning that there were enough people there with a broad-based area of expertise where you would know where you slotted in and where you needed to rely on your colleagues?
Right. The other part was I had already spent enough time working with them we could communicate. One of the conservators did finally say after I had been consulting with them for several years “Well, we can say this to you now John, for about the first two years we thought you talked nonsense. But now we’re beginning to understand what you’re saying.” It’s like okay. Well, I guess with the folks at the Gallery are the right people.
(Laughter) And what were the mechanics of you joining the gallery? Did they want you to join and then they had to go find external funding? Or you came with external funding? You had a relationship with Mellon?
No. They went off and actually got the funding for a position. The Gallery raised three quarters of a million dollars for a five-year position. And then they also made a commitment to provide the research money to build a laboratory which was a big deal.
Did you leave your previous work? Was it a leave of absence? What were the decisions there?
I did leave my previous job. Yeah, I did make a transition.
And what were your impressions when you got there in terms of the culture of the gallery, the kinds of people you’d be working with, and sort of the public mission of the gallery and being a part of that?
Partly it felt like a return to academics. There were very scholarly people their doing applied research. But then there was also the component that this was a first-class museum. And they wanted to do outreach and education to a broader group of people. So that part was new. The other part was similar. It felt about right in terms of the emphasis and there was a fair degree of freedom so long as you were working in the general mission of the museum, which was to study the and support the preservation of the collection. So, there were people that had specific questions they wanted to answer either for treatment or understanding the artwork. So, there were specific questions which I was used to in industry. And then it became well, how do we try to actually pull this off and get an answer? And then the gallery, because there are so few people working in this area, there was a lot of collaboration internationally with other museum science laboratories in France (Centre de recherche et de restauration des musées de France) and England (British Museum, the National Gallery, London). Thus, in the conservation science field you find yourself meeting all these international scientists who are coming from variety of backgrounds including physics and everyone was very positive.
The funding of conservation science research is different the U.S. is different than in other scientific fields. The majority of funding is from private foundations in the U.S. So, there is not a lot of applications to slog through, that is applying for ten grants, getting one. You know you kind of knew up front whether you had a chance with a private foundation. And these private foundations were often very involved in looking to see what was going on in the museums. And also looking ahead to see where they thought they should be funding.
To go back to this duality of basic science versus applied research and we’ll come back to this when we talk more about the specifics of your work at the gallery. But was your sense when you started that the overall goal was just discovery that you had these novel techniques and you could use them in this new media to just learn new things about science? Or was there more an applied component to it where there was a specific need in terms of what we needed to understand about these paintings, where they came from? And that was really the mission?
In this case I would say the focus was not on basic science but on applied science. The goal was to use the understanding of light interaction with mater, in this case the spectral range to work in order to reduce the light scattering of the lead white in the paint of the woman’s face to be able to see the black dots against gypsum white ground later. Thus, the knowledge of the physics was important, but so was identifying the optimal imaging system and doing practical experiments with paint outs. This latter part was the optimization part of the collective work.
John, to give a sense, maybe anecdotally as a narrative what would be an example of there’s a question surrounding a painting? You have an expertise that can help answer that question. And in the course of answering that question, here’s the net benefit that happens as a result either to the gallery itself, either to our history, either to the many scientific worlds that you’re a part of.
So, one of the big challenges is the identification of the specific paint binders that were used for a given painting. There are various ways to identify the pigments that are present in a painting. You can take a small paint sample and do extensive analytical analysis. You can use a non-invasive site-specific method such as x-ray fluorescence and get at the elements present which make up the pigment, for example is there lead there, is there chrome there? You can look at the reflection spectrum or the infrared spectrum from the site and try to discern the pigment from the absorption features. But identifying the paint binder is a pain in the neck. There is great interest in understanding the transition from tempera (water-based binders such as egg yolk, protein or gum Arabic (carbohydrate)) painting to oil painting. The optical index, drying properties of these binders are different and play an important role to the type of optical effects and artist can achieve with any given binder. So, people really want to know did they use egg tempera? Which was common before widespread adoption of oil. Or did they use oil? On the basis of visual inspection, conservators can make a good educated guess if the painting style looks more like egg tempera versus oil. And the only way to know for sure is literally to take a micro-sample of paint. And then using chronographic methods which are quite sensitive you know they can to identify what the paint binder.
The limitation of sampling methods is that you cannot make a map of paint binder or pigments present. And while making a map of pigments makes sense looking to see if other paint binders were used in a painting at first does not. However, artists have been adjusting the paint binder to optimize the visual effect. That is certain paint binders are better match for some pigments than others. And why that’s interesting because there are treatises that talked about for certain pigments you use let’s say, protein for like a blue pigment. And for other pigments, like a red, you’d use the egg yolk. Well, the egg yolk is slightly yellow, and if you mix it with a blue paint turn goes greenish. Besides the color effects there are issues of optical refractive index differences between the binder and the pigment that are important too.
For some pigments you want an optical refractive index difference to get opacity form light scattering and other cases you want them to match to make a transparent colored glaze. Thus, getting a map of the paint binders and pigments can be useful for those studying painting practice. This is one problem we thought we might be able to tackle using hyperspectral imaging in the shortwave infrared. Specifically, because there are absorption features associated with proteins, lipids (for atty acids) in the shortwave infrared, which we thought could be used to make maps of a few specific binders. If we could this would be an advance for the field and might be of general interest for the scientific community too. Fortunately, at this time the NSF Chemistry program had a call for analytical chemistry proposals that also involved problems in conservation science. So, we applied for, and received a joint grant with Prof. Murray Loew lab at in Electrical and Computer Engineering Dept. at George Washington University, to build a high-performance hyperspectral shortwave infrared camera and the software tools specifically to make maps of paint binders in paintings.
It worked pretty well, although not with the specificity of that obtained by micro-sample analysis. We compared our results with those from the micro-sample analysis of a painting (Cosmè Tura panel painting of Mary which is part of “The Annunciation with Saint Francis and Saint Louis of Toulouse [four panels]”, c. 1470/1480, in the collection of the National Gallery of Art) and good confirmation. The selection of painting binders Tura used for specific pigments match out nicely the way the recipes were suggested. Where we applied it next was to look at Jackson Pollock’s dripped paintings where it had been determined he used oil and alkyd paints from micro-samples. It was of interest because in these paintings, Jackson Pollock pools some of his paints and he also threw some of the paint them to make long lines. And the question was he using different binders for the paint used for pooling versus throwing. And people had taken samples and it seemed to hold up. But using the mapping methods we could get more clear understanding of his working methods. And that was a real step forward for the community to be able to look both at a large range of paint binders and have the ability to map on the macroscale.
And one of the oddest things that came out of this research on mapping paint binders was when we looked at the binders in an illuminated manuscript from a monk by the name of Lorenzo Monaco, who was painting in the fifteenth century in Florence. We had one of his illuminated cuttings that came from a book that is in the possession of the Bargello Museum in Florence. And from the hyperspectral imaging we determined that he had painted his illumination of the Praying Prophet egg yolk tempera which seemed insane to us. Because that’s how artist at the time were painting panel paintings but the recipes called for the use gum Arabic or animal skin protein for illuminated manuscripts which are painted in parchment. And then we went back to Florence to look at the remaining illuminations in the book from our illumination was cut out of in the late 1800s. Sure enough, all the illuminations that we looked at had egg tempera.
And what was interesting, the art historians who identified which artist had done which illumination in that book, they did it based on style. And a couple of them, they assigned not Lorenzo Monaco. But we basically argued, well because of the materials it has to be Lorenzo Monaco. So, that’s how we influence how people thought about the procedures that were being used and also it changed, added the new elements to how art historians make determination of who the artist would be. Not only by style but by looking at materials. The interest to the scientific community is we showed you could identify thin films of these different organic materials using this form of spectroscopy working in the spectral range. Why that was of interest was because it was an order of magnitude cheaper to build a camera system working in the shortware infrared than it was to build it in the mid or long wave IR where you could see absorption features associated with the same functional groups, a bit with more spectral features. They’re just unbelievably expensive to work out there. And the other problem is you’d have to work on unvarnished paintings because of limited penetration depth in the mid-IR. This means you have to work on old master paintings undergoing treatment when the varnish is removed. The vanish is less not much of a problem working in the SWIR.
John, as you were developing your expertise were you detecting globally that there was actually a broader world out there? There were people in this timeframe who were doing what you were doing? Or were you really that pathbreaker that was doing this stuff from your academic expertise for the first time?
When we started doing this work, there were some researchers who were taking the first steps. You know, they’d put a spectral imaging camera together. Or get something that was commercially available and then they would try it. They’d collect some data. Then they would show some reflectance spectra from a few sites on the painting. They’d make some comments about the pigments were and they would kinda end there. I think the part that we did early on that was different we went soup to nuts. We went from collecting the spectral image data or spectral image cubes (2-D spatial, 1-D spectral) to actually fully analyzing the image cubes to find a basis set of reflectance spectral endmembers, then make maps of where they are in the painting.
Next we used the spectral features as well other site based spectral analysis (i.e., x-ray florescence which provides element information) to identify the pigments that make up the spectral endmembers. In the end we end up adapting an image analysis procedure that was developed for remote sensing to do these steps. Most of this required a fair amount of manual image processing to go and classify and identify all of these artist materials (pigments and paint binders form the reflectance spectral data). So, I think we went much further in terms of making this a practical working system from image data collection to useful pigment maps. The other thing we did was to optimize the hyperspectral cameras, and the lighting, to make it work safer for the paintings. That is, we reduce the light intensities on the paintings needed to get good hyperspectral image cubes to light levels acceptable to conservators. Other groups have copied our cameras and or had companies modify their cameras to have similar light sensitivity. The Rijksmuseum have replicated of our camera system for the visible in the IR purchased really nice commercial system now on the market and The National Gallery, London, copied our cameras.
In terms of not relying on your colleagues either because you felt there were certain aspects that you needed to learn yourself or just as a matter of curiosity, what aspects of either art history or painting techniques have you felt like you wanted to learn more on your own that would be better for you to execute your job?
When we helped do the research on paintings for an exhibition on Verrocchio and important painter and sculpture during the Italian Renaissance. And Verrocchio’s workshop is where Leonardo learned painting. Well, if Leonardo ever learned painting from anybody, let’s say. I became interested in the how oil painting was adopted in this workshop. That is in some of the paintings you could see a transition from egg tempera painting to oil painting. The most complex painting we got to study for this exhibition where you see both the older style of egg tempera painting next to the newer oil painting was in Verrocchio and Leonardo painting The Baptism of Christ (1472–1475) which is at the Uffizi Museum in Florence.
Another problem involves how the painting in illuminated manuscripts are done. This problem is interesting to scholars both artistically but also in understanding how the workshops functioned. Because you have sort of a businesses that starts cropping up where people are preparing the skins for the parchment used for the pages of the books. They’re others doing some of layout of the music lines and the text in a scriptorium and then an artist is brought in to do the fancy painting. And then around these fancy paintings, done by these named artists, is the marginalia which consists of the large letter and lots fine details of flowers, or birds and exotic creatures like dragons. And the question is who did the designed and painted the marginalia, was it the painter or a lesser skilled person? Because there were guilds at the time which regulated what pigments or paint binders, they could use by which type of skilled artisan. So, there was a division of labor going on. So, you know, that’s been fun to learn about this history and see how our methods are helping flesh out this story for given artists and workshops.
Is there a style of painting, a particular era in art history, or even an artist in particular that you’ve come to admire from the very unique vantage point you bring to studying these paintings?
I spent a lot of time going to art museums in college and especially when I was in graduate school at The Rockefeller University. And when I was Rockefeller, I went often to Metropolitan Art Museum because you know, it was just a great place to go to and wonderful art and artifacts to see. So, I had gained a lot of interest in Dutch and Impressionist paintings. But I didn’t quite get Picasso, especially his synthetic cubist period. Which was the focus one of our first papers on reflectance imaging spectroscopy to identify and map arts pigments. When we started on this research the conservators suggested we try the experimental method on one of Picasso’s synthetic cubist Harlequin since it they have various fields uniform varying color, like, blues, oranges, yellow, reds etc. They thought this would be more straight forward with a limited set of pigments and thus, “you should be able to figure this out.” That when I found out Picasso was really interesting, instead of one blue pigment he used like three different blue pigment to achieve the color variations of the blue fields. The same turned out for the other colors as well. It was a very complicated painting in the end with over twenty-five different pigment mixtures. And when I first got to work on it, I was like, eh, not so excited. But when you light these paintings properly, which we were able to do, and you spend three months with it, you really, really realize why this painting’s in the collection at the National Gallery of Art. And I guess that’s what I’ve come to realize. You need to spend time and understand. Even Jackson Pollock is very cool once you spend enough time looking and thinking about it.
And you have the unique opinion to the cliched response, “Oh, I could do that.”
The best joke I saw recently was a man and a woman and a small kid, with another, with a small kid, they’re looking at Jackson Pollock and the guy says, “Oh, my kid could do that.” And you look at the kid’s face and you realize that’s the young Jackson Pollock.
That’s great (laughter). John, of course, intrigue has been a part of the art world for centuries. Either in terms of forgeries, either in terms of mistaken identities, either in terms of paintings hidden behind paintings. What have been some of the most exciting discoveries you’ve contributed to resolve some of these questions?
One of the things that was kind of neat was there was a small panel painting which is at the Kimbell Art Museum, which is thought to be by Michelangelo. A very young Michelangelo. That’s kind of what the art historians had worked out, but there were still some questions. And so, the Kimball Museum’s Head Paintings Conservator, Claire Berry, to see if I could help them understand some underdrawing or sketch that is beneath the paint layers using our infrared hyperspectral imaging camera. This painting by the way is The Torment of Saint Anthony and is thought to have been painted by Michelangelo when he was training in workshop of Domenico Ghirlandaio in Florence. Giorgio Vasari wrote that Ghirlandaio had Michelangelo make such a painting from an engraving of “Saint Anthony Tormented by Demons”. The painting is not just that engraving, but there is a scene with some rocky mountains below and valley. And by doing image processing transforms on the infrared hyperspectral image dataset we had collect we pulled out a small drawing that is beneath the paint layer of the rocks.
The drawing was just a sketch and it was not all that clear to me what it meant but were suggestive of something. And I gave the images of the sketch to Claire Berry and I said, “This looks interesting, but I don’t fully understand it.” And they spent some time with it. And they began to realize it was a small sketch of another painting that would’ve been worked on about this time by the fellow he was being trained by. This drawing of another known painting from the same workshop provided another piece of information tying painting of St Anthony in Torment to the workshop Michelangelo trained in. And thus, the Kimball were very excited about this as this was an independent piece of information placing the painting in the workshop Michelangelo trained in.
Another project that was turned out to be really cool was an infrared hyperspectral examination done in Japan looking on a blue period Picasso painting where we started turning up letters that were basically a transfer from a French newspaper to the painting at some point. And we got enough of the text that the curator that night was able to identify the newspaper, the date of the edition and the specific page. From the nature of the where the letters where they concluded Picasso had rolled the still partially wet painted canvas with pages from this newspaper for his trip from Paris back to Barcelona and that kind of nailed where that painting falls in the time line which had only been roughly known prior.
Related to the world of intrigue, art collecting of course is a multibillion-dollar business.
Yeah. Yeah, yeah.
In what ways is your research useful for making sure that the world of art collecting happens on the up and up. That people know what they’re getting?
So that’s one of the things by being in the museum environment, we’re not kind of in the business of looking at our work and giving advice about what they are. The best way I can kind of say it is, these scientific tools are very good at identifying materials. If you want to make an association between materials used by an artist, these methods, not only my own, but in general the scientific methods can help answer the question like did someone, in this painting are you finding a lot of it pigment that wasn’t available when he was working? And that has happened in the work of other scientists. And that just raises the question of whether this artwork is from the same time period. But it is really, really hard, except for those type of exceptions, to really go in and say you know, we could just say all this material was all correct for the fifteenth century, but stylistically and how the paint’s handled and the techniques, those are art historical questions, conservators’ questions that have to be relied on for authenticity. So, all we can do is some information about the material side of things. It’s still a very hard problem. There’s still a very important role for connoisseurship and close looking and comparing visually these objects.
On the question of authenticity, there’s a certain philosophical dimension that comes up when a forgery is so good either because of the materials or the technique that even at your level, the things that you’re looking at, it might be difficult for you to even determine those differences. I wonder if you’ve ever reflected on some of the philosophical questions that might arise from the nature of authenticity when the forger is essentially identical to the original?
Only from the vantage point that I have tremendous respect for my colleagues who really know how to look. Because they’re really good at looking and thinking about how the painting was made, and they’ve seen so many paintings and they have unique ability to recall such visual information form memory. They have an idea of how particular artists actually executed and painted things. And you see this with conservators. When they’re working on a painting, they will go and study the best-known works of that artist in order to better understand their working techniques, to go back and look at the painting they are working on. And the conservation process to cover over areas of losses. They do it in such a careful way that the retouching is fully removable from the painting without any risk. But also, they to do it in such a way that it doesn’t overshadow or take away from the artist, but at the same time pulls the composition together.
John, the question of art restoration, a question that’s sort of ripped from the headlines. One of the many awful things that happened with the insurrection on January 6th is that some really, really wonderful artwork got damaged on that day. My question is when a piece of art gets damaged, what opportunities do you have where in an otherwise pristine painting that you don’t want to damage, what opportunities do you have with the work that’s already been damaged where the art restorers have yet to get to work for you to do imaging or to study it in a way that might not be possible with an undamaged piece of art?
Well, when conservators are doing a conservation treatment, they will remove all of the overpaint and they will also remove all of the varnish. So, you’re left with what essentially is original paint. Having the opportunity to study the painting under those conditions is the best for us. Because then we get around certain optical effects from the varnish layers and we’re not misled by the inpainting. And that’s to our advantage. So, if we get something that needs to have that type of treatment, it’s the right time to look at it.
To go back to the administrative side of things, when the Mellon Fellowship ended and you faced the decision about what next, part of it must’ve been you realized that there was a lot more work that you needed to do. There was a full-time career ahead of you?
After several years it was becoming clear to me given the interest in the work as measured by number published papers, invitations to give talks at conservation science meetings as well as invitations to study paintings at other museums moment was going in the right direction. So yes, there as a full-time career ahead of me from what I could see. Moreover, our success has I think justified other museums to hire imaging scientists in a similar role. And it’s expanding forward. And it’s great because now we have a variety of people doing similar work, coming up with new approaches, clever approaches, which makes all the more fun. And now we now have periodic meetings where a part of the meeting is on this type imaging.
You know the field has matured when there are now regular meetings (laughter).
Yeah! Yeah, it’s good. The part that’s really cool is to work with young scientists and see them go forth and take the tools and carve out their own life. And start doing new things with it. And that’s and ultimately you know, I wanted to be participating in that part of science, in that part of the education. And I have.
Kind of a really broad question. Because the National Gallery of Art of course has a public mission and part of that mission is education and outreach. To what extent does that mission really positively affect the kind of work you’re able to do and the kinds of audience that you might be able to reach beyond your own scientific community?
One of the things that we’ve been able to do is to bring in technologists and companies with instrumentation. And bring them in to try it out. You know, to get those people involved. And that as a result gets other companies to start thinking about marketing their equipment and modifying it for the community. So, you suddenly have people supplying equipment that are optimized for the artwork. So that’s part of it.
And a kind of fun way is my colleague and I who’s an imaging scientist who is now permanent with us; she started off as a fellow with me. We gave a Sunday lecture. And the Sunday lecture is open to the broad public. And we gave it basically explaining our techniques. Some of the things we learned. And our approach was to say, “Most of you people know about remote sensing from NASA. You know about the Mars Rover and looking for evidence for water on Mars. And doing minimal identification. Looking for those blue marbles.” And basically, we said, “We’re doing the same thing on the paintings. Trying to identify these materials without doing the touching.” And that was a good synergy for the broader public. It was extremely well attended. And we have a lot of technology people at the meeting who have an interest in art, but also have an interest in these technology aspects. And I think that’s sort of one of the untapped areas at some of these museums where we have such a technology driven society where people know a lot about technology and are extremely well trained. It’s another way to bring them in.
And we’ve seen this in Europe. There was a study of Vermeer’s painting the Girl with a Pearl Earring where they set up a crystal house around the area of the painting so the public could watch the conservators and scientists conduct their examination of the painting. And we were invited along with a variety of cultural heritage scientists to come and use our tools to study the painting with the public there. And showing our some of results as we got them. We were running around with our black lab coats. And it was a lot of fun to see these kids and their parents coming to see the artwork and then to see scientists working on them and follow the latest results. So, I hope there’s more of that in the future especially as an opportunity for teaching. And I do know that some universities, particularly Washington and Lee, one of the chemistry professors, Prof. Erich Uffelman, has mixed in the study of artist materials and painting techniques to his chemistry class to bring in students who are studying art history. And then he takes them to Europe with equipment, some of the equipment that we’ve sort of pioneered in and gets them to study paintings. And helps do some of the analysis for the conservators who lack such instruments. And so now, you have this beautiful mix of science and art. And he’s teaching them the quantum mechanics and chemistry and also teaching about the Dutch genre painting at the same time. So, it’s just, it’s pretty cool.
John, just to bring the narrative up to the present. We already talked at the beginning of our discussion about what you’ve been doing remotely since the pandemic, but before that you know, the last five years or so, what have been some of your major initiatives?
Um, we’ve gotten more involved with helping support exhibitions. So, we’ve gone from answering specific questions for conservators and curators to now are participating in broader studies. That is looking works of art that would be part of an exhibition and trying to help provide new insights for essays to be written for the catalog for the exhibition. And we did this for an exhibition titled “Fragonard: The Fantasy Figures.” These are a group of brightly colored paintings of lavishly costumed individuals painted by Jean-Honoré Fragonard (1732–1806) that appear to have been quickly painted. And they’re quite compelling. The relationship between these paintings was established on their style as there is no written record establishing their relationship. And what was particularly interesting about the Fragonard Fantasy painting in the Galley’s collection, which is of a young woman reading a book her gaze is not outwards like the other paintings but directly at her book. It looks like it’s painted like one of these Fantasy Figures. It’s definitely by Fragonard, but she’s not looking out engaging the audience. She’s just looking at her book. So, it doesn’t fit the style of people in fancy dress looking out. A few years before the exhibition a drawing showed up on the market which was identified as a drawing by Fragonard which consisted of quick thumbnail sketches of a lot of these Fantasy Figures. So, now there’s evidence that Fragonard associated all these paintings together. Except the thumb nail drawing of the painting that would fit ours, was of a woman holding a book but looking out.
And so, we were asked to go look at that painting in detail with our infrared hyperspectral imaging as well as x-ray fluorescence imaging spectroscopy to make element maps to see if we could suss it out it. They had known earlier from an x-ray radiograph there was a face of someone looking out, but they thought it was likely a man, not a woman, based on visual characteristics. But the infrared hyperspectral imaging we did provided pretty solid evidence that it was a face of a woman. She had a black tie around her neck. And we got enough to see that she had slightly reddish hair from the elemental map of mercury. And we got enough information about how she appeared that one of the trained painting conservators with photoshop was able to essentially paint in what the face originally appeared using the various technical images we had. The simulation was quite good and pretty close to how the original painting must’ve looked and fit well with the other fantasy figures. It fits in perfectly what this sketch was and what they knew the history of what happened to this painting. Fragonard had painted this picture of this woman holding a book looking out. Then the painting showed up in a catalog for sale twenty years after as a painting with a woman looking at her book- someone had sketched the painting as it appeared next to the entry in the catalog. The thought by Dr. Yuriko Jackall, the curator of the exhibition, is Fragonard quickly painted over the portrait of the woman looking out to a more generic young girl looking at her book to increase the paintings sale. So that answered quite a bit.
Well, John, now that we’ve worked up to the present, I want to ask for the last part of our talk a broadly retrospective question and then one looking forward. So, first you know, I’m coming from AIP from the Niels Bohr Library so I’m going to ask a physics question. And there’s one that it goes all the way back to the beginning of your academic interests as an undergraduate. So, I wonder if you can reflect broadly at the National Gallery of Art the work that you do. In what ways does physics, physics concepts, physics techniques really inform both the day-to-day and also your intellectual approach to your career?
Right. So, what we’ve tried to do is make use of physical models, light interaction with matter. You know, look at things like surface roughness properties of paints are reduced by vanishes and how the different artists’ materials are used, how those change to understand the visual effect, and why things get classified by conservators and curators who say, “This works for me and this doesn’t.” So, relating the visual experience back the to the optical and material properties of paints. So, that’s been a big component of it. The other component of it has been in terms of trying to understand the reflection spectra that we get from these layered paint materials. Most people who do hyperspectral reflectance look at an optically thick material that’s homogenous. We are looking at different materials (pigment particles) that are intermittently mixed and suspended in an optical binder so there’s light scattering and absorption going on. So, the light interaction is nonlinear and then as we go into the infrared scattering and optical depth penetration changes and it allows us to access different paint layers below.
We’re also starting to move into more advanced algorithms for processing our large spectral image cubes. Even for a small painting we can end up with image cubes that have fifty million spectra to parse through. We have to do some sort of multivariant statistical analysis to reduce the data to a minimum number of basis spectra. And so, we’ve moved on to working with mathematicians and physicist in the Imaging Science Center at Rochester Institute of Technology and the imaging science center there, some of their neural networks to try to do the classification of the spectra directly to pigment mixtures. So, to me there is another case we looked at was looking at trap emission from semiconductors that turn out to be used for pigments like cadmium paints as a way to find and identify them when they’re mixed with other pigments by using the trap emission in the infrared. So, that’s very much of a physics problem. And then using that to exploit it as a technique to find these pigments.
John, looking ahead to the future both in terms of what you want to accomplish as a mentor, as a scientist, and as a public servant. What are some of the goals that you have and what are you most optimistic about in terms of where this field which you essentially created ultimately is heading?
Well, I’ll say I’ll share the creation with a few other individuals. I won’t stick my head out that far. I think that for me in the long term is to write book chapters or even a book that focus on reflectance imaging spectroscopy of paintings from the light interaction with the pigments in the paint layer and the various hyperspectral camera designs, data processing strategies and cases studies. So, it’s like an academic textbook for especially the conservation science field. That’s one area. Another area is to focus on the educational aspect to use this as a hook or a tool to get people outside of the sciences interested in the sciences. From the humanities. And on the other side, to bring engineers, technologists, scientists, and make them aware of what’s interesting about the art area. About the soft humanities. And you know make that crossover more. That would be a goal in the future as well. And that’s part of the mission. The other trick is to try to come up with a better tool, a better instrumentation that learns. So, one of the things that I think would be a lot of fun, right now we scan all of our paintings with these different imaging modalities and we fuse the datasets together. But it’d be rather clever since of all this sort of compressive sensing that’s been done, to flip the problem around and say, I know this is a picture allegedly by an Impressionist painter. So, I know kind of what pigments should be there. Can I build a box that looks at the color information, predicts what pigments should be there, and only has to do these type of measurements at say a few thousand points. And then evolve itself and test other places and build up a model without doing all the scanning. So, that’s kind of new direction I would like to explore.
John, it’s been so fun spending this time with you. I have learned a tremendous amount. I really want to thank you for sharing your insights. It’s really been great talking with you.
Thank you. It’s been a real pleasure talking with you. And you are, you really pulled out a lot of stuff.
Mission accomplished (laughter).