RESUMO
Differential cross sections for Compton scattering from the proton have been measured at scattering angles of 55°, 90°, and 125° in the laboratory frame using quasimonoenergetic linearly (circularly) polarized photon beams with a weighted mean energy value of 83.4 MeV (81.3 MeV). These measurements were performed at the High Intensity Gamma-Ray Source facility at the Triangle Universities Nuclear Laboratory. The results are compared to previous measurements and are interpreted in the chiral effective field theory framework to extract the electromagnetic dipole polarizabilities of the proton, which gives α_{E1}^{p}=13.8±1.2_{stat}±0.1_{BSR}±0.3_{theo},ß_{M1}^{p}=0.2∓1.2_{stat}±0.1_{BSR}∓0.3_{theo} in units of 10^{-4} fm^{3}.
RESUMO
BACKGROUND: Withdrawal of life support and organ procurement for transplantation are the main implications of a diagnosis of brain stem death (BSD). Various factors may impact this important decision-making process. The present study sought to investigate the knowledge and attitudes about BSD among university undergraduates as a "well-informed" subgroup of our local population. METHODS: A cross-sectional questionnaire survey was administered to a sample of nonmedical university undergraduate students in Hong Kong. RESULTS: The subjects' overall knowledge of BSD was unsatisfactory. Only 24% of subjects knew that BSD was the equivalent of legal death in Hong Kong. Among subjects who agreed to withdraw life support treatment from themselves upon the diagnosis of BSD, 30% and 24% refused to do so for their family members or a stranger, respectively. Subjects who agreed to withdraw life support showed significantly better knowledge about BSD than did those who did not agree. Concerns about doctors' inclination to diagnose BSD to save resources and extract organs for transplantation were not observed to negatively affect subjects' decisions about life support withdrawal. CONCLUSION: The level of knowledge is an important factor affecting an individual's decision concerning withdrawal of life support therapy upon the diagnosis of BSD. Adequate explanation and counseling are important to facilitate family members in coping with this important end-of-life issue.