满足美国未来的能源需求

在未来的年代,获得充足能源的挑战是如此之大,围绕全球原油与天然气供应的不确定性是如此真实,以致传统的争论将会很快地被抛之脑后。能源生产与能源保护是一把剪刀的两个刀刃,缺一不可。制定一种切合实际的能源政策是极为困难的,因为能源政策是包括经济、政治、环境问题、军事需求和外交策略的混合物。美国是一个最大的原油进口国,在天然气进口上也是如此。很明显,能源是一个全球性问题,有关这一问题的任何一项认真研究所得出的结论都是,未来1 0年美国对外来能源的依赖会越来越强。同样的一些研究还指出,循环发生的世界范围的能源供应问题…     

The role of support person for Ngaanyatjarra women during pregnancy and birth

BackgroundThis study took place in a remote community on the Ngaanyatjarra Lands, Western Australia. Ngaanyatjarra women's cultural practices have been subject to erosion during the past 70 years. Women are now expected to birth hundreds of kilometres from home and, due to financial barriers, without family support. Older women lament their lack of input into, and control of, contemporary birthing services.Research questionIn order to provide culturally appropriate maternity services we asked: What issues would the Ngaanyatjarra women of the community like to see resolved in the area of antenatal and birthing services?Participants and methodsEligible participants were any Ngaanyatjarra women of the study community who had birthed at least once. We utilised a participatory research methodology. 36 women were interviewed.FindingsThis paper discusses one finding related to support for child-bearing women. The role is important in many ways. Ngaanyatjarra women did not traditionally have their support persons with them during labour and birth, nor do they necessarily expect them to be present in current times. Most women do, however, wish to have a support person with them during antenatal checkups and when they travel to town to await birth.ConclusionAboriginal women from remote communities should be able to have a support person with them when they access regional birthing services, but the nature of this role must not be assumed. A culturally appropriate service has input from the community, provides options and respects choices.     

Imputation of missing variance data using non-linear mixed effects modelling to enable an inverse variance weighted meta-analysis of summary-level longitudinal data: a case study

Missing variances, on the basis of the summary-level data, can be a problem when an inverse variance weighted meta-analysis is undertaken. A wide range of approaches in dealing with this issue exist, such as excluding data without a variance measure, using a function of sample size as a weight and imputing the missing standard errors/deviations. A non-linear mixed effects modelling approach was taken to describe the time-course of standard deviations across 14 studies. The model was then used to make predictions of the missing standard deviations, thus, enabling a precision weighted model-based meta-analysis of a mean pain endpoint over time. Maximum likelihood and Bayesian approaches were implemented with example code to illustrate how this imputation can be carried out and to compare the output from each method. The resultant imputations were nearly identical for the two approaches. This modelling approach acknowledges the fact that standard deviations are not necessarily constant over time and can differ between treatments and across studies in a predictable way.     

Analysis of dose-response in flexible dose titration clinical studies

Assessing dose-response from flexible-dose clinical trials (e.g., titration or dose escalation studies) is challenging and often problematic due to the selection bias caused by 'titration-to-response'. We investigate the performance of a dynamic linear mixed-effects (DLME) model and marginal structural model (MSM) in evaluating dose-response from flexible-dose titration clinical trials via simulations. The simulation results demonstrated that DLME models with previous exposure as a time-varying covariate may provide an unbiased and efficient estimator to recover exposure-response relationship from flexible-dose clinical trials. Although the MSM models with independent and exchangeable working correlations appeared to be able to recover the right direction of the dose-response relationship, it tended to over-correct selection bias and overestimated the underlying true dose-response. The MSM estimators were also associated with large variability in the parameter estimates. Therefore, DLME may be an appropriate modeling option in identifying dose-response when data from fixed-dose studies are absent or a fixed-dose design is unethical to be implemented.     

Beyond speculative robot ethics: a vision assessment study on the future of the robotic caretaker

In this article we develop a dialogue model for robot technology experts and designated users to discuss visions on the future of robotics in long-term care. Our vision assessment study aims for more distinguished and more informed visions on future robots. Surprisingly, our experiment also led to some promising co-designed robot concepts in which jointly articulated moral guidelines are embedded. With our model, we think to have designed an interesting response on a recent call for a less speculative ethics of technology by encouraging discussions about the quality of positive and negative visions on the future of robotics.     

Sculpted landscapes: art & place in Cleveland's Cultural Gardens, 1916-2006

Perhaps the world's first peace garden, the Cleveland Cultural Gardens embody the history of twentieth-century America and reveal the complex interrelations between art and place. This essay uses the Cleveland Cultural Gardens as a lens through which to explore how art and place have intersected over time. It explores how communities have negotiated questions of national, ethnic, and American identity and embedded those identities into the vernacular landscape. It considers how the particulars of place were embedded into a public garden and asks whether it is possible for public art to transcend its place—both in terms of geography and history. In some sense, the Gardens have transcended their place, but in others respects, their fortunes were bound inextricably to that place, to the economic, demographic, and cultural contours that shaped and reshaped Northern Ohio. As works of art, the Cleveland Cultural Gardens both have reflected the history of Cleveland and American industrial cities during the 20th century and revealed something of the dynamics that underscored the changing character of public art and gardens in American cities.     

Semiparametric Efficient Estimation for a Class of Generalized Proportional Odds Cure Models

We present a mixture cure model with the survival time of the "uncured" group coming from a class of linear transformation models, which is an extension of the proportional odds model. This class of model, first proposed by Dabrowska and Doksum (1988), which we term "generalized proportional odds model," is well suited for the mixture cure model setting due to a clear separation between long-term and short-term effects. A standard expectation-maximization algorithm can be employed to locate the nonparametric maximum likelihood estimators, which are shown to be consistent and semiparametric efficient. However, there are difficulties in the M-step due to the nonparametric component. We overcome these difficulties by proposing two different algorithms. The first is to employ an majorize-minimize (MM) algorithm in the M-step instead of the usual Newton-Raphson method, and the other is based on an alternative form to express the model as a proportional hazards frailty model. The two new algorithms are compared in a simulation study with an existing estimating equation approach by Lu and Ying (2004). The MM algorithm provides both computational stability and efficiency. A case study of leukemia data is conducted to illustrate the proposed procedures.