Beamline AR-NW12A: high-throughput beamline for macromolecular crystallography at the Photon Factory.

AR-NW12A is an in-vacuum undulator beamline optimized for high-throughput macromolecular crystallography experiments as one of the five macromolecular crystallography (MX) beamlines at the Photon Factory. This report provides details of the beamline design, covering its optical specifications, hardware set-up, control software, and the latest developments for MX experiments. The experimental environment presents state-of-the-art instrumentation for high-throughput projects with a high-precision goniometer with an adaptable goniometer head, and a UV-light sample visualization system. Combined with an efficient automounting robot modified from the SSRL SAM system, a remote control system enables fully automated and remote-access X-ray diffraction experiments.

The influence of acute hypoxia on the prediction of maximal oxygen uptake using multi-stage shuttle run test.

BACKGROUND: The purpose of this study was to investigate changes in predicted maximal oxygen uptake (VO(2max)) by the multistage shuttle run test (MSSR) and several physiological parameters in MSSR under normoxia and two hypoxic conditions and the influences of acute hypoxia on these changes in MSSR. EXPERIMENTAL DESIGN: six college long distance runners (LR), seven college rugby athletes (RG) and eight untrained college males (UM) performed incremental running test on the treadmill and MSSR in 17.5% (HYP(17.5%)) and 15.5% (HYP(15.5%)) of oxygen concentration and normoxia (NOR(20.9%)). MEASURES: VO(2max) was measured by the treadmill protocol and predicted by MSSR. Maximal heart rate (HR(max)) and maximal blood lactate concentration (BLa(max)) were recorded at the termination of each test. RESULTS: Significant correlation was observed between measured VO2(max) by the treadmill protocol (57.2+/-8.3 ml x kg(-1) x min(-1)) and predicted VO(2max) in NOR(20.9%) (54.6+/-8.0 ml x kg(-1) x min(-1)) (r=0.80, p<0.05). Also strong correlations in predicted VO(2max) between NOR(20.9%) and HYP(17.5%) (51.1+/-8.0 ml x kg(-1) x min(-1)) (r=0.90, p<0.05) and between NOR(20.9%) and HYP(15.5%) (48.1+/-7.3 ml x kg(-1) x min(-1)) (r=0.82, p<0.05) were observed. CONCLUSIONS: The results show that although MSSR underpredicts VO(2max), it is effective to evaluate aerobic power and can detect the influence of oxygen concentration on aerobic power. The specific movement of MSSR may affect the performance of LR but MSSR can describe the influence of hypoxia on the performance of LR compared to normoxia. Thus MSSR can be used to evaluate the influence of hypoxia or altitude on aerobic power as a field test.

Ab initio structure determinations by direct-space methods: tests of low-density elimination.

The low-density elimination method, which was developed for phase extension and refinement, has been investigated regarding its power to solve crystal structures starting from completely random phase sets. The method employs a multi-solution strategy. Low-symmetry structures are easily solvable where phase restrictions are only applied to a few reflections. Even with high-symmetry structures, a reasonable solution was obtained regarding centric reflections as general reflections. It is also shown that the structure of a small protein ribonuclease Ap1 is solvable if the positions of the five S atoms in the protein are known.