Search for stable strange quark matter in lunar soil.

We report results from a search for strangelets (small chunks of strange quark matter) in lunar soil using the Yale WNSL accelerator as a mass spectrometer. We have searched over a range in mass from A = 42 to A = 70 amu for nuclear charges 5, 6, 8, 9, and 11. No strangelets were found in the experiment. For strangelets with nuclear charge 8, a concentration in lunar soil higher than 10(-16) is excluded at the 95% confidence level. The implied limit on the strangelet flux in cosmic rays is the most sensitive to date for the covered range and is relevant to both recent theoretical flux predictions and a strangelet candidate event found by the AMS-01 experiment.

Responsiveness and predictability of gait speed and other disability measures in acute stroke.

OBJECTIVES: To identify the most responsive method of measuring gait speed, to estimate the responsiveness of other outcome measures, and to determine whether gait speed predicts discharge destination in acute stroke. DESIGN: A prospective cohort study. SETTING: Five acute-care hospitals. PATIENTS: Fifty subjects with residual gait deficits after a first-time stroke. INTERVENTIONS: Five- (5mWT) and 10-meter walk tests (10mWT) at comfortable and maximum speeds, with 2 evaluations conducted an average +/- standard deviation (SD) of 8 +/- 3 and 38 +/- 5 days poststroke. MAIN OUTCOME MEASURE: Standardized response mean (SRM = mean change/SD of change) was used to estimate responsiveness for each walk test, the Berg Balance Scale, the Barthel Index, the Stroke Rehabilitation Assessment of Movement (STREAM), and the Timed Up and Go (TUG). RESULTS: The SRMs were 1.22 and 1.00 for the 5mWT, and.92 and.83 for the 10mWT performed at a comfortable and maximum pace, respectively. The SRMs for the Berg Balance Scale, the Barthel Index, the STREAM, and the TUG were 1.04,.99,.89, and.73, respectively. The probability of discharge to a rehabilitation center for persons walking at < or = 0.3m/s or > 0.6m/s at the first evaluation was.95 and.22, respectively. CONCLUSIONS: The 5mWT at a comfortable pace is recommended as the measure of choice for clinicians and researchers who need to detect longitudinal change in walking disability in the first 5 weeks poststroke.

Rural hospital costs: an analysis with policy implications.

The 1977 National Guidelines for Health Planning suggest a maximum of 4 hospital beds per 1,000 population and a minimum occupancy rate of 80 percent for those beds as desirable for an efficient local hospital system. Rural areas often have more than 4 hospital beds per 1,000 population and generally exhibit occupancy rates well below the rate specified by the Guidelines. Hence, there appears to be an opportunity for reducing the cost of hospital services in rural areas by providing care with fewer beds concentrated in larger, better utilized facilities. This paper presents estimates of the annual savings that would result from following such a policy in rural areas. The statistically estimated cost curves are based on data from a sample of 116 rural hospitals for the years 1971-77. With a quadratic specification for the cost function, the hospital size that minimizes average costs is estimated to be 113 beds, and the occupancy rate that minimizes costs is 73 percent. Hospitals with 113 beds are estimated to have average costs per patient day that are from $6.51 (logarithmic specification) to $15.15 (quadratic specification) below the average cost per patient day of a 41-bed hospital, the average size of the hospitals in the sample. Hospitals with a 73 percent occupancy rate are estimated to have average costs that are $5.96 logarithmic specification to $11.75 (quadratic specification) lower than the average costs in hospitals with 51 percent occupancy rates, the average in the sample, if other factors are held constant. These benefits can be weighed by health policy analysts against the increased cost of travel and ambulance service, and the accompanying increase in risk to patients, to determine if the present structure for the delivery of acute care in rural areas warrants change.