David Sayre

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David Sayre (born March 2, 1924 in New York City , † February 23, 2012 ) was an American crystallographer , computer scientist and physicist .

life and work

Sayre studied at Yale University with a bachelor's degree in 1943. 1944/45 he worked on the radar at the MIT Radiation Laboratory . After the war, he continued his studies at Auburn University with a master's degree in 1948, turned to crystallography and received his doctorate in 1951 under Dorothy Hodgkin at Oxford University .

In 1952 he developed an equation named after him, which became one of the foundations of the direct methods in crystallography - it allows probable values ​​for the phase to be obtained from the X-ray diffraction image. Another work from 1952 is considered to be one of the foundations for the techniques of Coherent Diffraction Imaging (CDI) developed from the 1980s onwards . In his work he applied the findings of Claude Shannon ( Nyquist-Shannon sampling theorem ) to the phase problem in X-ray crystallography and showed that the solution of the problem is promoted by a higher resolution of the diffraction image (in a higher resolution than the usual Bragg reflections ).

A program Sayre wrote as part of structure determination by X-ray crystallography at the University of Pennsylvania caught the attention of John W. Backus , who brought him to IBM in 1956 , where he was one of ten programmers working on the original Fortran code. He was the assistant manager of the Fortran development group and later corporate director for programming. In the 1960s he headed the Programming Research Group and developed the first operating system with virtual memory management at IBM. In the M44 / M44X project from IBM, time sharing and virtual memory concepts were tested from the mid-1960s. Sayre and his team came to the conclusion that virtual memory was superior to the best overlay structures hand-knitted by programmers. These experiments eliminated the remaining doubts of computer system architects and software engineers about the virtual storage concept.

In 1971 he proposed the use of electron beam lithography, which was then just developed for chip production, for the manufacture of Fresnel zone plates for X-ray microscopes . His idea was realized in the 1980s. One of his doctoral students (Wenbing Yun) founded a company Xradia for this purpose. After a stay in Oxford in 1972/73 with Dorothy Hodgkin is Sayre turned back the X-ray diffraction to and development of X-ray microscopes, first in the laboratory and later after his retirement from IBM at the Synchrotron Radiation Source National Synchrotron Light Source of the Brookhaven National Laboratory . Sayre stayed at IBM until 1990, when he was Adjunct Professor at the State University of New York at Stony Brook .

As early as 1980 he realized that with the X-rays from synchrotron radiation sources his ideas from 1952 on diffraction images with higher resolution to solve the phase problem could be realized and he then participated in the development of Coherent Diffraction Imaging (CDI) or Diffraction Microscopy . He worked with his students Henry Chapman and John Miao.

His wife Anne Sayre, whom he met in Oxford and married in 1947, wrote the book Rosalind Franklin and DNA in the 1950s as a result of acquaintance with Rosalind Franklin . One motive was to correct James D. Watson's point of view in his book Double Helix , which systematically downplayed Rosalind Franklin's role.

In 1983 he was President of the American Crystallographic Association , whose Fan Cake Award he received in 1989. In 2008 he received the Ewald Prize of the International Union of Crystallography for his contributions to crystallography .

literature

Individual evidence

  1. ↑ D. Sayre: The squaring method: a new method for phase determination . In: Acta Crystallographica . tape 5 , no. 1 , 1952, pp. 60-65 , doi : 10.1107 / S0365110X52000137 .
  2. ^ D. Sayre: Some implications of a theorem due to Shannon . In: Acta Crystallographica . tape 5 , no. 6 , November 1952, p. 843-843 , doi : 10.1107 / S0365110X52002276 .
  3. ↑ D. Sayre: Is automatic “folding” of programs efficient enough to displace manual? In: Commun. ACM . tape 12 , no. December 12 , 1969, p. 656-660 , doi : 10.1145 / 363626.363629 .
  4. ^ Peter J. Denning: Performance modeling - experimental computer science at its best . ( Memento of September 28, 2011 in the Internet Archive ) 1981 (PDF).
personal data
SURNAME Sayre, David
BRIEF DESCRIPTION American physicist, computer scientist and crystallographer
DATE OF BIRTH March 2, 1924
PLACE OF BIRTH New York City
DATE OF DEATH February 23, 2012