Working at the Institut Laue Langevin

For the past few weeks I have been working with my friend and collaborator Maxime at the ILL in Grenoble, France.  We’ve been working on a paper about the effects of fluctuations on proteins.  It’s been really fun being the odd-one-out experimentalist amidst this group of dyed in the wool theorists.

Back in the lab, Dileep and Gabe are making enormous progress on the AFM.  After just a few weeks of working in the lab it seems that they don’t need me at all!

Interesting paper on bulk nanorheology

Maxime Clusel sent me a link to this paper, “Elasticity of Globular Proteins Measured from the ac Susceptibility,” by Y Wang and G Zocchi.  It details a beautiful experiment in which they measure the linear visco-elastic response of glubular proteins and short DNA molecules.  They use the molecules to tether electrically charged gold nanoparticles to a surface and then excite the molecules by applying an electric potential and inducing movement of the nanoparticles.  The resulting change in particle-surface distance (i.e. the amount that the molecule has stretched) is measured by evanescent wave scattering, which ends up with a resolution on the average extension of many molecules of ~ 0.1 Å!  Incredible!

Glue logic between circuits

Why don’t all digital circuits use the same voltage levels!?  I know that there are actually good reasons for this, relating to underlying physical processes, the particular demands of the circuit, and historical accident.  But that doesn’t make it any less frustrating to realize that the 3V “true” that my FPGA puts out is interpreted as a “false” by my ADC.  Luckily, I am not the first person in the world to have this problem, and with Cliff Dax’s expert knowledge the problem will soon be solved with some TTL latches and pull-up resistors.