Effects of weight-shift training on walking ability, ambulation, and weight distribution in individuals with chronic stroke: a pilot study.

BACKGROUND: People with gait difficulties after a stroke usually have an asymmetrical gait and slower gait speed than age-matched controls. These difficulties restrict people with stroke in their daily life activities. OBJECTIVE: This pilot study sought to evaluate the effects of weight-shift training on gait, weight distribution in standing, and ambulation in people with gait difficulties after a stroke. METHODS: Ten subjects with chronic stroke (3-11 years since insult) and remaining gait difficulties participated in a 3-week weight-shift training program. Spatial and temporal gait parameters were assessed pre-, post-, and 3-month post-training with a motion analysis system. Weight distribution was assessed with force plates and ambulation with the Swedish version of the Clinical Outcome Variables Scale (S-COVS). Wilcoxon signed-rank tests were used to explore differences between test occasions. RESULTS: Significant changes were seen between pre-and post-tests in decreased stance time on the non-paretic leg (P = 0.005) and increased score on the S-COVS (P = 0.043). At the 3-month follow-up test, the subjects had also increased their gait speed significantly (P = 0.037). Standing weight distribution did not change between pre- and post-tests (P = 0.575), but between the pre-and follow-up tests it shifted from the paretic leg to the non-paretic (P = 0.007). CONCLUSION: Weight-shift training seems to improve gait and ambulation in subjects with chronic stroke, but not with standing weight distribution. However, this pilot study has several limitations and a larger sample size with a control group is necessary.

Light induced suppression of sulfur in a cesium sputter ion source.

New techniques for suppression of atomic isobars in negative ion beams are of great interest for accelerator mass spectrometry (AMS). Especially small and medium-sized facilities can significantly extend their measurement capabilities to new interesting isotopes with a technique independent of terminal voltage. In a new approach, the effect of continuous wave laser light directed towards the cathode surface in a cesium sputter ion source of the Middleton type was studied. The laser light induced a significant change in oxygen, sulfur and chlorine negative ion production from a AgCl target. Approximately 100 mW of laser light reduced the sulfur to chlorine ratio by one order of magnitude. The effect was found to depend on laser power and ion source parameters but not on the laser wavelength. The time constant of the effect varied from a few seconds up to several minutes. Experiments were first performed at the ion beam facility GUNILLA at University of Gothenburg with macroscopic amounts of sulfur. The results were then reproduced at the VERA AMS facility with chemically cleaned AgCl targets containing ∼1 ppm sulfur. The physical explanation behind the effect is still unclear. Nevertheless, the technique has been successfully applied during a regular AMS measurement of 36Cl.