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John J. Gagliardi Don Kim Jennifer J. Sokol Larry A. Zazzera Vincent D. Romero Matthew R. Atkinson Faisal Nabulsi Harry Zhang 《Journal of Manufacturing Processes》2013,15(3):348-354
An alternative, and potentially better, means to process prime LED sapphire wafers is proposed. A brief history of material removal mechanisms suggests that brittle materials can be abraded in a ductile regime and that this can be a superior mode of removal. Advantages in material removal rate, surface finish and subsurface damage for a 2-body ductile removal of sapphire are shown relative to 3-body material removal. A major difficulty with this approach may be getting the LED manufacturing industry to understand that the appearance of the sapphire surface is quite different, unfamiliar yet predictable. Finally, some potential alternative process approaches are discussed that utilize 2-body material removal. 相似文献
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A fundamental requirement of task regulation in social groups is that it must allow colony flexibility. We tested assumptions
of three task regulation models for how honeybee colonies respond to graded changes in need for a specific task, pollen foraging.
We gradually changed colony pollen stores and measured behavioral and genotypic changes in the foraging population. Colonies
did not respond in a graded manner, but in six of seven cases showed a stepwise change in foraging activity as pollen storage
levels moved beyond a set point. Changes in colony performance resulted from changes in recruitment of new foragers to pollen
collection, rather than from changes in individual foraging effort. Where we were able to track genotypic variation, increases
in pollen foraging were accompanied by a corresponding increase in the genotypic diversity of pollen foragers. Our data support
previous findings that genotypic variation plays an important role in task regulation. However, the stepwise change in colony
behavior suggests that colony foraging flexibility is best explained by an integrated model incorporating genotypic variation
in task choice, but in which colony response is amplified by social interactions.
Received: 17 October 1998 / Received in revised form: 11 March 1999 / Accepted: 12 March 1999 相似文献
476.
Jennifer Hoguet Peter B. Key 《Journal of environmental science and health. Part. B》2013,48(6):465-470
This study investigated differences in baseline levels of four cellular biomarkers (glutathione (GSH), lipid peroxidation (LPx), acetylcholinesterase (AChE), and cholesterol (CHL)) in the larval, juvenile, and adult stages of the estuarine amphipod, Leptocheirus plumulosus. Glutathione, LPx, and AChE exhibited the same pattern of decreasing levels with increasing developmental stage. Cholesterol showed an inverse relationship of increasing levels with increasing developmental stages. This research provides valuable background information that may be used in future assessments of amphipod biomarker research. 相似文献
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Courtland L. Smith Jennifer Gilden 《Journal of the American Water Resources Association》2002,38(3):653-662
ABSTRACT: Oregon watershed council leaders, members, and government supporters are working to improve watershed health. To identify the institutional assets that are most helpful in taking action, we assemble the lessons learned from several synthesis studies. The institutional assets fall into seven categories — leadership, vision, trust, social networks, capital, power, and local and technical knowledge. Scientific knowledge, leadership, vision, and social networks are the assets most widely recognized and available. Power, trust, and capital are challenges that must be met for actions to be successful. Most people affected by watershed council actions can appeal to more powerful interests to get these actions changed. Trust, particularly of scientific recommendations and government, is lacking. This distrust limits opportunities for watershed council actions. 相似文献
479.
Eleanor Harding Jennifer Hammond Lyn S. Chitty Melissa Hill Celine Lewis 《黑龙江环境通报》2020,40(8):1028-1039
Background
Tests in pregnancy such as chromosomal microarray analysis and exome sequencing are increasing diagnostic yield for fetal structural anomalies, but have greater potential to result in uncertain findings. This systematic review investigated the experiences of prospective parents about receiving uncertain results from these tests.Methods
A systematic search of three electronic databases was conducted. Data extraction was performed for studies that met the eligibility and quality criteria. Results were synthesised following the principles of thematic analysis.Results
Fourteen studies (10 qualitative, 4 quantitative) were included. Findings were grouped into three overarching themes. Sources of uncertainty included the testing procedure, the diagnosis and prognosis, and health professionals' own uncertainty. The clinical impact of the uncertainty included parents struggling to make clinical decisions with the information available, the emotional impact included decisional-regret, shock, worry and feeling overwhelmed. To manage the uncertainty, parents sought support from healthcare professionals, friends, family, the internet and other parents as well as remaining hopeful.Conclusions
Prospective parents experience a myriad of uncertainties in the prenatal setting, which must be handled sensitively. Future research should explore optimal ways of managing uncertainty to minimise harm. Recommendations are made for discussing uncertainty during pre- and post-test counseling. 相似文献480.
Timber harvest transforms ecological roles of salmon in southeast Alaska rain forest streams 总被引:1,自引:0,他引:1
Scott D Tiegs Dominic T Chaloner Peter Levi Janine Rüegg Jennifer L Tank Gary A Lamberti 《Ecological applications》2008,18(1):4-11
Although species commonly modify habitats and thereby influence ecosystem structure and function, the factors governing the ecological importance of these modifications are not well understood. Pacific salmon have repeatedly been shown to positively influence the abundance of benthic biota by annually transferring large quantities of nutrients from marine systems to the nutrient-poor freshwaters in which they spawn. Conversely, other studies have demonstrated that salmon can negatively influence the abundance of freshwater biota, an effect attributed to bioturbation during upstream migration and nest construction. The factors determining which of these contrasting ecological effects predominates are unknown, including how human activities, such as land use, influence ecological responses to salmon. We sampled a key basal food resource, sediment biofilm, in seven southeast Alaskan streams impacted to varying degrees by timber harvest. Biofilm abundance (measured as chlorophyll a and ash-free dry mass) was positively related to timber-harvest intensity prior to salmon arrival. However, during the salmon run, an inverse relationship emerged of more abundant biofilm in less-harvested watersheds. Among-stream variability in biofilm response to salmon was largely explained by sediment particle size, which was larger in less-harvested watersheds. Collectively, these results suggest that, by altering stream sediment size, timber harvest transformed the dominant effect of salmon from nutrient enrichment to physical disturbance, thus modifying nutrient linkages between marine and freshwater ecosystems. 相似文献