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- David A. Langs, Dr. Yan -Shi Guo, Herbert A. Hauptman
- Acta crystallographica. Section D, Biologicalâ€¦
- 1995

A procedure is described by which the phase-invariant translation function may be used to provide starting set phases for the minimal function that are significantly better than those generated fromâ€¦ (More)

- Herbert A. Hauptman, Dr. Yan -Shi Guo, Hong-Liang Xu, Robert H. Blessing
- Acta crystallographica. Section A, Foundations ofâ€¦
- 2002

As a basis for direct-methods phasing at very low resolution for macromolecular crystal structures, normalized structure-factor algebra is presented for few-atoms structure models with N = 1, 2, 3,â€¦ (More)

- Dr. Yan -Shi Guo, Robert H. Blessing, David A. Langs, Herbert A. Hauptman
- Acta crystallographica. Section A, Foundations ofâ€¦
- 1997

Results from probabilistic theory for the single-wavelength anomalous-scattering (SAS) Friedel pair, two-phase structure invariants, psi H = phi H + phi-H, are used to show that the SAS three-phaseâ€¦ (More)

- Robert H. Blessing, Dr. Yan -Shi Guo, David A. Langs
- Acta crystallographica. Section D, Biologicalâ€¦
- 1996

If the unit-cell distribution of atomic mean-square displacement parameters B = 8pi(2) is assumed to be normal, with mean micro = and variance sigma(2) = <(B-)(2)>, the statistical expectation valueâ€¦ (More)

- Dr. Yan -Shi Guo, Robert H. Blessing, David A. Langs
- Acta crystallographica. Section D, Biologicalâ€¦
- 2000

It is shown that for crystals of large proteins at low diffraction resolution, with N approximately 10 000 independent non-H protein atoms and d(min) approximately 8 A, a simple bulk-solventâ€¦ (More)

- David A. Langs, Dr. Yan -Shi Guo, Herbert A. Hauptman
- Acta crystallographica. Section A, Foundations ofâ€¦
- 1995

A new strategy for employing three phase triples invariant estimates from Hauptman's single isomorphous replacement (SIR) and anomalous dispersion (SAS) joint probability distribution formulae isâ€¦ (More)

- Dr. Yan -Shi Guo, Gareth D. Smith, Jane F. Griffin, David A. Langs
- Acta crystallographica. Section A, Foundations ofâ€¦
- 1995

At 3 to 4 A resolution, the electron density of a protein may be modeled by a continuous chain of 'globs' representing the amide region of the peptide backbone and the side-chain residues. Groupâ€¦ (More)

- Dr. Yan -Shi Guo, Robert H. Blessing, David A. Langs, Gareth D. Smith
- Acta crystallographica. Section D, Biologicalâ€¦
- 1999

Using Harker's [Harker (1953). Acta Cryst. 6, 731-736] idea of spherically averaged polyatomic groups or 'globs' as the units of structure suitable for analyzing low-resolution diffraction data fromâ€¦ (More)

- Dr. Yan -Shi Guo, Robert H. Blessing, Herbert A. Hauptman
- Acta crystallographica. Section A, Foundations ofâ€¦
- 1991

Results of a statistical study of probabilistic estimates of two-phase structure invariants (TPSI) for Friedel pairs in the case of single-wavelength anomalous scattering are reported. Numericalâ€¦ (More)

- David A. Langs, Robert H. Blessing, Dr. Yan -Shi Guo
- Acta crystallographica. Section A, Foundations ofâ€¦
- 2001

Single-wavelength anomalous dispersion (SAS) data can in principle be phased by direct methods since a priori estimates of the three-phase structure invariants can be computed from these data. Theâ€¦ (More)