A critique is made of Bernard Rollin's examination of the ethics of cloning adult mammalian cells. The primary concern is less to propound an anticloning or procloning position than to call for full exploration of the ethical complexities before a rush to judgment is made. Indeed, the ethical examination in question rushes toward an ethical position in such a way that does not appear consistent with Rollin's usual methodology. By extending this methodology – which entails full weighing of benefits and costs – it becomes apparent that there are real potential risks to this type of cloning in both animals and humans, besides the possible benefits, and that the scientific, political, philosophical, and broader academic communities should explore these risks and benefits extensively. Rollin's usual methodological call for hesitation before risks would translate into hesitation before the ethical risks of adult mammalian cell cloning instead of his paper's curiously laissez-faire stance. 相似文献
The combined mark-recapture and line transect sampling methodology proposed by Alpizar-Jara and Pollock [Journal of Environmental and Ecological Statistics, 3(4), 311–327, 1996; In Marine Mammal Survey and Assessment Methods Symposium. G.W. Garner, S.C. Amstrup, J.L. Laake, B.F.J. Manly, L.L. McDonald, and D.C. Robertson (Eds.), A.A. Balkema, Rotterdam, Netherlands, pp. 99–114, 1999] is used to illustrate the estimation of population size for populations with prominent nesting structures (i.e., bald eagle nests). In the context of a bald eagle population, the number of nests in a list frame corresponds to a pre-marked sample of nests, and an area frame corresponds to a set of transect strips that could be regularly monitored. Unlike previous methods based on dual frame methodology using the screening estimator [Haines and Pollock (Journal of Environmental and Ecological Statistics, 5, 245–256, 1998a; Survey Methodology, 24(1), 79–88, 1998b)], we no longer need to assume that the area frame is complete (i.e., all the nests in the sampled sites do not need to be seen). One may use line transect sampling to estimate the probability of detection in a sampled area. Combining information from list and area frames provides more efficient estimators than those obtained by using data from only one frame. We derive an estimator for detection probability and generalize the screening estimator. A simulation study is carried out to compare the performance of the Chapman modification of the Lincoln–Petersen estimator to the screening estimator. Simulation results show that although the Chapman estimator is generally less precise than the screening estimator, the latter can be severely biased in presence of uncertain detection. The screening estimator outperforms the Chapman estimator in terms of mean squared error when detection probability is near 1 wheareas the Chapman estimator outperforms the screening estimator when detection probability is lower than a certain threshold value depending on particular scenarios. 相似文献
Samples of adipose tissue from 7 male persons and 10 samples of human milk were analyzed for 3,3′,4,4′-tetrachlorobiphenyl by HRGC-HRMS. The levels found are in the lower ppt-range on a fat weight basis 相似文献
Objective: Adaptive cruise control (ACC), a technology that allows for automated car following, is becoming increasingly prevalent. Previous surveys have shown that drivers generally regard ACC as pleasant but that they have to intervene when the ACC reaches its operational limits. The former research has been mostly concerned with specific car brands and does not fully reflect the diversity of ACC types in traffic today. The objective of the present research was to establish the determinants of pleasure in using ACC.
Methods: A 55-item online questionnaire was completed by Dutch users of diverse ACC systems.
Results: Respondents (N = 182) rated their ACC highly, with a mean score of 8.0 on a scale from 1 (extraordinarily negative) to 10 (extraordinarily positive) and were most pleased with ACC on high-speed roads and in low-density traffic. Moreover, the findings point to specific operational limits such as associated with cut-in situations. Pleasure was greater for the types of ACC that are able to decelerate to a full stop, according to 48% of our sample. An analysis of the free-response items indicated that respondents who were displeased with ACC mentioned its occasional clumsiness and the dangerous situations it may evoke, whereas those who were pleased with ACC valued the complementarity of human and machine and emphasized the roles of responsibility and experience in using ACC.
Conclusion: Pleasure in using ACC is a function of both technological advances and human factors. 相似文献