Polarized gamma-ray emission from the crab.

Pulsar systems accelerate particles to immense energies. The detailed functioning of these engines is still poorly understood, but polarization measurements of high-energy radiation may allow us to locate where the particles are accelerated. We have detected polarized gamma rays from the vicinity of the Crab pulsar using data from the spectrometer on the International Gamma-Ray Astrophysics Laboratory satellite. Our results show polarization with an electric vector aligned with the spin axis of the neutron star, demonstrating that a substantial fraction of the high-energy electrons responsible for the polarized photons are produced in a highly ordered structure close to the pulsar.

The risks, benefits, and costs of expanding donor criteria. A collaborative prospective three-year study.

The study purpose was to identify risks, benefits and costs associated with an expanded donor protocol. The protocol design evaluated organs rescued using expanded donor criteria and weighed all costs associated with doing so. Costs were measured against conditions experienced with expanded and traditional criteria and recipient outcome. Traditional donors were between 5 and 55, with negative serologies, and no history of hypertension or diabetes. "Expanded donors" were between 55 and 75 or less than 5, with a history of hypertension, diabetes and/or sero-positive for Hepatitis C. During this study 73 donors met criteria from which 200 organs were transplanted. Defined costs and outcomes for recipients were tracked. Using expanded criteria: costs averaged 20% more per organ; OPO personnel spent an average of 6 hours more time on-site; an additional 12-14 hours in placement activity; and average organs per donor decreased. Heart patient and graft survival rates for traditional and expanded donor organs were comparable. Kidney patients transplanted from this pool experienced a decrease in patient (P = .14) and a significant decrease in graft (P = .02) survival rates. Patient (P = .05) and graft (P = .01) survival rates were significantly lower in liver patients transplanted with expanded donor organs. Two hundred transplants occurred using expanded donor criteria. Costs for the OPO increased appreciably. Heart and kidney utilization from these donors seems justified. It is thought that liver recipients' results were due to utilizing them in sicker patients. Recovery of organs from donors using expanded criteria appears to be a reasonable way of increasing organ supply.