New applications for RPT?

From: André Dolenc (Helsinki University of Technology)
Date: Sunday, March 13, 1994

From: André Dolenc (Helsinki University of Technology)
Date: Sunday, March 13, 1994
Subject: New applications for RPT?
  Manufacturing Chromosomes And Viruses: A New Application Area For RPT?
  Dr. A. Dolenc      HUT/IIA
  R. Hovtun          SI-SINTEF
  Dr. P. Engelhardt  Department of Virology, Helsinki University
  J. Ruokolainen     VTKK/Center for Scientific Computing (Finland)

     On February 23rd, 1994 the first scaffold\footnote{The scaffold is the ``skeleton'', i.e. depleted of DNA by enzymatic digestion.}  of a human chromosome was manufactured at SINTEF (Norway). It was the last of a long chain of events that began at the Department of Virology from the Helsinki University. Dr. Peter Engelhardt performed the delicate task of preparing the chromosome for a picture session. This includes introducing markers that are subsequently used as reference points for the 3D~reconstruction. EM photographs of tilted series from $0^o$ to $60^o$ with steps of $3^o$ were taken. The photographs were then used for constructing a 3D model of the chromosome.
     The construction of the 3D CAD model and it's conversion to the STL format was performed by Juha 
Ruokolainen at the Center for Scientific Computing. The STL file contained more than $700000$ triangles, and, due to noise and lack of accuracy in the process, several disconnected components. The STL file was then processed at the Institute of Industrial Automation using software tools described in the previous Newsletter. After removing the noise, we were left with 4~components.
     It was vital that these components retained their spatial relationship after manufacturing, and, therefore, the model had to be modified. The only Rapid Prototyping process that has the required software tools is the  SOLIDER process from Cubital. The model was then sent electronically to SINTEF in Norway (via {\tt ftp}), and bars were added to the model.  Bars were also needed to enhance the rigidity of the physical model.
     Chromosomes are extremely complex. Several visualization techniques are used to understand their 
structure, including electron microscopic tomography, hidden line removal, stereo projections, and animations. Physical models, though, may become an indispensible tool for researches in the field.

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