Laboratory Scale Slow Cook-Off Testing of Rocket Propellants: The Combustion Rate Analysis of a Slowly Heated Propellant (CRASH-P) Test.

Solid rocket propellants are widely used for propulsion applications by military and space agencies. Although highly effective, they can be dangerous to personnel and equipment under certain conditions, with slow heating in confined conditions being a particular danger. This paper describes a more affordable laboratory test that is easier to set up and was developed for screening rocket propellant ingredients. Rocket propellants are cast into sample holders that have been designed to have the same confinement as standard rocket motors (propellant volume to total volume in the container) and ensure that the propellant is not easily vented. Reaction violence is quantified by the time it takes to reach 90% of the maximum pressure after autoignition, which is analogous to blast overpressure gauges used to measure violence in a full-scale test. A positive correlation was observed between the speed and pressure produced from the reaction and the power produced by the rocket propellant during the reaction.

The economic impact of MELD on liver transplant centers.

Adoption of the model for end stage liver disease (MELD) system prioritized patients awaiting liver transplant (LT) by severity of illness including progressive renal dysfunction. Unfortunately, current reimbursement for LT is not adjusted by severity of illness or need for simultaneous liver-kidney transplantation (LKT). This study examines hospital cost and reimbursement for LT and LKT to determine the effect of MELD on transplant center (TC) financial outcomes given current reimbursement practices as well as DRG outlier threshold limits. LT was performed for 86 adults prior to and 127 following the implementation of MELD. Between the eras, there was a substantial increase in the average laboratory MELD score (17.1 to 20.7 p=0.004) and percentage of LKTs performed (5.8% to 17.3% p=0.01). Increasing MELD score was associated with higher costs ($4309 per MELD point p<0.001) and decreasing TC net income ($1512 per MELD point p<0.001). In patients not achieving the Medicare outlier status, predicted net loss was $17,700 for high-MELD patients and $19,133 for those needing LKT. In conclusion, contractual reimbursement agreements that are not indexed by severity of disease may not reflect the increased costs resulting from the MELD system. Even with outlier thresholds, Medicare reimbursement is inadequate resulting in a net loss for the TC.