Intersecting Methods 2016: Almost There

And again, I bring you two more prints from the Intersecting Methods portfolio. Today, we reveal the editions of David Gerhard and Douglas Bosley. Click here for David’s bio post and click here for Douglas’.

Here is David’s statement about his print.

“Manufactured Rainbow,” Inkjet Print on Dutch Etching Paper & Limited Edition Access to Digital Files, 14”x18”, 2016

 Friendships come and go. Intersecting for a brief period, friendships can be on and off, and sometimes for a longer part of our lives. Manufactured Rainbows is more about these kinds of friendships than about an artist and scientist coming together to work on an academic project. Once much closer, we had always wanted to work together on a print. During the months that followed, we saw less of each other, and found the first and second meeting to be planning a project that didn’t end up the way we had planned.

 Manufactured Rainbows is chronicling our conversations working out David’s idea to manufacture a 3D printing rainbow machine out of a silo. Manufactured Rainbows is also showing the interaction of people who used to be close friends whose relationship changed over time. Life took us in different directions, but our friendship became archived in our project notes. The imagery originated with the sighting of a rainbow in the sky, but was digitally augmented so many times that it became a semblance of the real thing, an abstract document of an actual event. The final print includes text directly referencing our meeting notes creating a sort of dialogue. We leave our viewers with a parting gift, sort of a party favor for stepping into a moment of our friendship.

Douglas wrote this statement for his print.

“Isomorphous Replacement,” Mezzotint, 18”x14”, 2016

 One of the main tools for protein structure determination is Fourier Analysis, or the mathematical description of a complex waveform as a sum of constituent sine functions.  A sample protein crystal is bombarded with a beam of x-rays and the diffraction from those rays measured.  The diffraction pattern is a series of thousands of tiny dots.  These individual dots or intensities can be represented as sine waves, and the sum of these waves corresponds to electron density in the sample.

 Performing these calculations would be relatively straightforward if not for one thing.  To define a sine wave three terms are required: amplitude, wavelength, and phase.  The first two are readily determined from the diffraction data, but not the phase. Measuring both phase and amplitude simultaneously in a single measurement is impossible due to the uncertainty principle.  This is called the ‘phase problem,’ and several techniques exist for estimating or determining a useful phases. 

 This print deals with the phase problem, and one possible solution called ‘isomorphous replacement.’  Two or more isomorphous derivatives of the target protein are created with metal ions incorporated.  Since metal atoms are heavier than the organic atoms that typically make up a protein, they can be easily picked out from a special waveform of the data called a Patterson Function (the square of the amplitude is used in place of the unknown phase term).  Once located, the intensities of the heavy atoms can be compared to the contributions of the native protein.  In a vector space it is then possible to solve for the phase at the locations of heavy atom replacement; with two derivatives and one native protein this is akin to triangulation of the correct phase.  These phases can be used to estimate phases for the remaining intensities, and thus calculate a low-resolution electron density function for the entire protein.  With initial estimates of phases the density function will appear blobby, and may have large regions of false positive or negative density.  However, phase estimates can be improved by statistical modeling, and the whole model is iteratively improved since each improved phase estimate will yield better estimates in the future.

There is one final print for the 2016 Intersecting Methods portfolio. Sadly, the participant has had some trouble finishing the edition. Once, I receive the final print I will post it on the blog, create a page on the R&D editions website and begin working on preparing the two portfolios for possible future exhibitions.

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