1,108 research outputs found

    Strong light-matter coupling in ultrathin double dielectric mirror GaN microcavities

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    Strong light-matter coupling is demonstrated at low temperature in an ultrathin GaN microcavity fabricated using two silica/zirconia Bragg mirrors, in addition to a three-period epitaxial (Al,Ga)N mirror serving as an etch stop and assuring good quality of the overgrown GaN. The λ/2 cavity is grown by molecular beam epitaxy on a Si substrate. Analysis of angle-resolved data reveal key features of the strong coupling regime in both reflectivity and transmission spectra at 5 K: anticrossing with a normal mode splitting of 43±2 meV and 56±2 meV for reflectivity and transmission, respectively, and narrowing of the lower polariton linewidth near resonance

    Enhancing the Value of Cover Crops through Utilization by Beef Stocker Cattle: Progress Report (Year 2)

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    The increase in cover crops across Iowa presents a substantial amount of potential forage available to the beef industry that would otherwise go unutilized. While the benefits of improved soil health and nutrient retention through cover crops are well known, limited data are available on utilization by beef cattle. Thus, a study was designed to measure cattle performance while spring grazing cereal rye and to evaluate the impact grazing had on the soil profile. Preliminary data suggests that with proper supplementation, cattle grazing cereal rye may achieve average daily gains of 1.5 to 3.0 lb/d. Initial analysis of soil bulk density indicates minimal negative changes in compaction due to grazing. Because many variables impact the successful integration of cover crops and livestock into row crops, this is a four-year study summarizing data from year two

    Cancellous bone and theropod dinosaur locomotion. Part III—Inferring posture and locomotor biomechanics in extinct theropods, and its evolution on the line to birds

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    This paper is the last of a three-part series that investigates the architecture of cancellous bone in the main hindlimb bones of theropod dinosaurs, and uses cancellous bone architectural patterns to infer locomotor biomechanics in extinct non-avian species. Cancellous bone is highly sensitive to its prevailing mechanical environment, and may therefore help further understanding of locomotor biomechanics in extinct tetrapod vertebrates such as dinosaurs. Here in Part III, the biomechanical modelling approach derived previously was applied to two species of extinct, non-avian theropods, Daspletosaurus torosus and Troodon formosus. Observed cancellous bone architectural patterns were linked with quasi-static, three-dimensional musculoskeletal and finite element models of the hindlimb of both species, and used to derive characteristic postures that best aligned continuum-level principal stresses with cancellous bone fabric. The posture identified for Daspletosaurus was largely upright, with a subvertical femoral orientation, whilst that identified for Troodon was more crouched, but not to the degree observed in extant birds. In addition to providing new insight on posture and limb articulation, this study also tested previous hypotheses of limb bone loading mechanics and muscular control strategies in non-avian theropods, and how these aspects evolved on the line to birds. The results support the hypothesis that an upright femoral posture is correlated with bending-dominant bone loading and abduction-based muscular support of the hip, whereas a crouched femoral posture is correlated with torsion-dominant bone loading and long-axis rotation-based muscular support. Moreover, the results of this study also support the inference that hindlimb posture, bone loading mechanics and muscular support strategies evolved in a gradual fashion along the line to extant birds

    A review of the US Global Change Research Program and NASA's Mission to Planet Earth/Earth Observing System

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    This report reflects the results of a ten-day workshop convened at the Scripps Institution of Oceanography July 19-28, 1995. The workshop was convened as the first phase of a two part review of the U.S. Global Change Research Program (USGCRP). The workshop was organized to provide a review of the scientific foundations and progress to date in the USGCRP and an assessment of the implications of new scientific insights for future USGCRP and Mission to Planet Earth/Earth Observing System (MTPE/EOS) activities; a review of the role of NASA's MTPE/EOS program in the USGCRP observational strategy; a review of the EOS Data and Information System (EOSDIS) as a component of USGCRP data management activities; and an assessment of whether recent developments in the following areas lead to a need to readjust MTPE/EOS plans. Specific consideration was given to: proposed convergence of U.S. environmental satellite systems and programs, evolving international plans for Earth observation systems, advances in technology, and potential expansion of the role of the private sector. The present report summarizes the findings and recommendations developed by the Committee on Global Change Research on the basis of the presentations, background materials, working group deliberations, and plenary discussions of the workshop. In addition, the appendices include summaries prepared by the six working groups convened in the course of the workshop

    Tenure & Turnover among State Health Officials from the SHO-CASE Survey: Correlates & Consequences of Changing Leadership

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    Objective: To examine characteristics associated with tenure length of State Health Officials (SHOs) and examine reasons and consequences for SHO turnover. Design: Surveys of current and former SHOs linked with secondary data from the United Health Foundation. Setting: Original survey responses from SHOs in the United States. Participants: Respondents included SHOs who served between 1973 and 2017. Main Outcome Measures: Tenure length and consequences of SHO turnover. Results: Average completed tenure among SHOs was 5.3 years (median = 4) and was shorter in recent time periods compared with decades prior. Older age at appointment (β = −0.109, P = .005) and those holding a management degree (β = −1.835, P = .017) and/or a law degree (β = −3.553, P < .001) were each associated with shorter SHO tenures. State Health Officials from states in the top quartile for health rankings had significantly longer average tenures (β = 1.717, P = .036). Many former SHOs believed that their tenure was too short and reported that their departure had either a significant or very large effect on their agency's ability to fulfill its mission. Conclusions: State Health Official tenures have become shorter over time and continue to be shorter than industry chief executive officers and best practice recommendations from organizational researchers. States have an opportunity to consider and address how factors within their control influence the stability of the SHO position

    Design and methodology of a cluster-randomized trial in early care and education centers to meet physical activity guidelines: Sustainability via Active Garden Education (SAGE)

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    Strategies are needed to help early care and education centers (ECEC) comply with policies to meet daily physical activity and fruit and vegetable guidelines for young children. This manuscript describes the design and methodology of Sustainability via Active Garden Education (SAGE), a 12-session cluster-randomized controlled crossover design trial using community-based participatory research (CBPR) to test a garden-based ECEC physical activity and fruit and vegetables promotion intervention for young children aged 3–5 years in 20 sites. The SAGE curriculum uses the plant lifecycle as a metaphor for human development. Children learn how to plant, water, weed, harvest, and do simple food preparation involving washing, cleaning, and sampling fruit and vegetables along with active learning songs, games, science experiments, mindful eating exercises, and interactive discussions to reinforce various healthy lifestyle topics. Parents will receive newsletters and text messages linked to the curriculum, describing local resources and events, and to remind them about activities and assessments. Children will be measured on physical activity, height, and weight and observed during meal and snack times to document dietary habits. Parents will complete measures about dietary habits outside of the ECEC, parenting practices, home physical activity resources, and home fruit and vegetable availability. SAGE fills an important void in the policy literature by employing a participatory strategy to produce a carefully crafted and engaging curriculum with the goal of meeting health policy guidelines and educational accreditation standards. If successful, SAGE may inform and inspire widespread dissemination and implementation to reduce health disparities and improve health equity
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