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Richard Friedberg

Publications and source records attributed to Richard Friedberg.

2 recordsLinked to original sources

Efficient sorting of genomic permutations by translocation, inversion and block interchange.

MOTIVATION: Finding genomic distance based on gene order is a classic problem in genome rearrangements. Efficient exact algorithms for genomic distances based on inversions and/or translocations have been found but are complicated by special cases, rare in simulations and empirical data. We seek a universal operation underlying a more inclusive set of evolutionary operations and yielding a tractable genomic distance with simple mathematical form. RESULTS: We study a universal double-cut-and-join operation that accounts for inversions, translocations, fissions and fusions, but also produces circular intermediates which can be reabsorbed. The genomic distance, computable in linear time, is given by the number of breakpoints minus the number of cycles (b-c) in the comparison graph of the two genomes; the number of hurdles does not enter into it. Without changing the formula, we can replace generation and re-absorption of a circular intermediate by a generalized transposition, equivalent to a block interchange, with weight two. Our simple algorithm converts one multi-linear chromosome genome to another in the minimum distance.

Algorithms↗

Quality indicators of blood utilization: three College of American Pathologists Q-Probes studies of 12,288,404 red blood cell units in 1639 hospitals.

OBJECTIVES: To determine the normative rates of blood unit crossmatched to transfused (C:T) ratios, red blood cell (RBC) unit wastage, and RBC unit expiration that exist in hospital communities throughout the United States, and to examine hospital blood bank practices associated with more desirable (lower) rates. DESIGN: In 3 separate studies, participants in the College of American Pathologists Q-Probes laboratory quality improvement program collected data retrospectively on the number of transfusion crossmatches performed in their institutions and the number of RBC-containing units that were transfused into patients, the number of units that expired (outdated) prior to being utilized, and the number that were wasted due to mishandling. Participants also completed questionnaires describing their hospitals' and blood banks' laboratory and transfusion practices. SETTING AND PARTICIPANTS: One thousand six hundred thirty-nine public and private institutions, well more than 80% of which were known to be located in the United States. MAIN OUTCOME MEASURES: Quality indicators of blood utilization (namely, the C:T ratio, the rate of RBC unit expiration, and the rate of RBC unit wastage). RESULTS: Participants submitted data on 12,288,404 RBC unit transfusions. The C:T ratios were 1.5 or less in the top-performing 10% of participating institutions (90th percentile and above), 1.8 to 1.9 in the midrange of participating institutions (50th percentile), and 2.4 or greater in the bottom-performing 10% of participating institutions (10th percentile and below). Red blood cell unit expiration rates were 0.1% or less at the 90th percentile and above, 0.3% to 0.9% at the 50th percentile, and 3.5% or greater at the 10th percentile and below. Red blood cell unit wastage rates were 0.1% or less at the 90th percentile and above, 0.1% to 0.4% at the 50th percentile, and 0.7% or greater at the 10th percentile and below. Depending on which quality indicator was examined, lower values (ie, better performances) were found in institutions that had fewer than 200 hospital beds, no teaching programs, no on-site full-time medical directors of transfusion services, did not utilize maximum surgical blood order schedules, set C:T threshold goals of 2.0 or less, monitored categories of health care workers responsible for RBC wastage, monitored requests for RBC components by transfusion indication, did not accept short-dated units from blood distribution centers, and if they did accept short-dated units, were allowed to return those units to the distribution centers. CONCLUSIONS: Hospital blood bank personnel can achieve C:T ratios below 2.0, RBC unit expiration rates below 1.0%, and RBC unit wastage rates below 0.5%. Lower C:T ratios and/or RBC unit expiration rates were associated with blood bank personnel setting C:T thresholds of 2.0 or less, monitoring requests for blood components by transfusion indication criteria, monitoring categories of health care workers responsible for blood wastage, not accepting short-dated units from blood distribution centers, and if short-dated units were accepted, being allowed to return those units to the blood distribution center. These practices were not associated with lower blood wastage rates.

Blood Banks↗