344 research outputs found

    Effect of Sting Geometry on Axial Force Calculation for the Space Launch System

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    The primary purpose of this study is to determine the extent to which the size and shape of the wind tunnel sting affect the accuracy of the base pressure corrections applied to measured axial force. The study also includes an assessment of the overall accuracy of the corrections. To accomplish these goals, Computational Fluid Dynamics is used to simulate a simplified version of the geometry of the Space Launch System Block 1B Cargo configuration, paired with a range of wind tunnel sting sizes, over a variety of ascent flight conditions. The base pressure correction method used in the wind tunnel is emulated on the base pressures from the simulated flows and results are compared to direct integration of the base pressures. Differences in results between the two methods provides an assessment of the accuracy of the base force correction method and how that accuracy is affected by sting size

    Contrasting Development of Canopy Structure and Primary Production in Planted and Naturally Regenerated Red Pine Forests

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    Globally, planted forests are rapidly replacing naturally regenerated stands but the implications for canopy structure, carbon (C) storage, and the linkages between the two are unclear. We investigated the successional dynamics, interlinkages and mechanistic relationships between wood net primary production (NPPw) and canopy structure in planted and naturally regenerated red pine (Pinus resinosa Sol. ex Aiton) stands spanning ≥ 45 years of development. We focused our canopy structural analysis on leaf area index (LAI) and a spatially integrative, terrestrial LiDAR-based complexity measure, canopy rugosity, which is positively correlated with NPPw in several naturally regenerated forests, but which has not been investigated in planted stands. We estimated stand NPPw using a dendrochronological approach and examined whether canopy rugosity relates to light absorption and light–use efficiency. We found that canopy rugosity increased similarly with age in planted and naturally regenerated stands, despite differences in other structural features including LAI and stem density. However, the relationship between canopy rugosity and NPPw was negative in planted and not significant in naturally regenerated stands, indicating structural complexity is not a globally positive driver of NPPw. Underlying the negative NPPw-canopy rugosity relationship in planted stands was a corresponding decline in light-use efficiency, which peaked in the youngest, densely stocked stand with high LAI and low structural complexity. Even with significant differences in the developmental trajectories of canopy structure, NPPw, and light use, planted and naturally regenerated stands stored similar amounts of C in wood over a 45-year period. We conclude that widespread increases in planted forests are likely to affect age-related patterns in canopy structure and NPPw, but planted and naturally regenerated forests may function as comparable long-term C sinks via different structural and mechanistic pathways

    Organizational readiness for implementing change: a psychometric assessment of a new measure

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    Abstract Background Organizational readiness for change in healthcare settings is an important factor in successful implementation of new policies, programs, and practices. However, research on the topic is hindered by the absence of a brief, reliable, and valid measure. Until such a measure is developed, we cannot advance scientific knowledge about readiness or provide evidence-based guidance to organizational leaders about how to increase readiness. This article presents results of a psychometric assessment of a new measure called Organizational Readiness for Implementing Change (ORIC), which we developed based on Weiner’s theory of organizational readiness for change. Methods We conducted four studies to assess the psychometric properties of ORIC. In study one, we assessed the content adequacy of the new measure using quantitative methods. In study two, we examined the measure’s factor structure and reliability in a laboratory simulation. In study three, we assessed the reliability and validity of an organization-level measure of readiness based on aggregated individual-level data from study two. In study four, we conducted a small field study utilizing the same analytic methods as in study three. Results Content adequacy assessment indicated that the items developed to measure change commitment and change efficacy reflected the theoretical content of these two facets of organizational readiness and distinguished the facets from hypothesized determinants of readiness. Exploratory and confirmatory factor analysis in the lab and field studies revealed two correlated factors, as expected, with good model fit and high item loadings. Reliability analysis in the lab and field studies showed high inter-item consistency for the resulting individual-level scales for change commitment and change efficacy. Inter-rater reliability and inter-rater agreement statistics supported the aggregation of individual level readiness perceptions to the organizational level of analysis. Conclusions This article provides evidence in support of the ORIC measure. We believe this measure will enable testing of theories about determinants and consequences of organizational readiness and, ultimately, assist healthcare leaders to reduce the number of health organization change efforts that do not achieve desired benefits. Although ORIC shows promise, further assessment is needed to test for convergent, discriminant, and predictive validity

    Update to the study protocol for an implementation-effectiveness trial comparing two education strategies for improving the uptake of noninvasive ventilation in patients with severe COPD exacerbation

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    BACKGROUND: There is strong evidence that noninvasive ventilation (NIV) improves the outcomes of patients hospitalized with severe COPD exacerbation, and NIV is recommended as the first-line therapy for these patients. Yet, several studies have demonstrated substantial variation in NIV use across hospitals, leading to preventable morbidity and mortality. In addition, prior studies suggested that efforts to increase NIV use in COPD need to account for the complex and interdisciplinary nature of NIV delivery and the need for team coordination. Therefore, our initial project aimed to compare two educational strategies: online education (OLE) and interprofessional education (IPE), which targets complex team-based care in NIV delivery. Due to the impact of the COVID-19 pandemic on recruitment and planned intervention, we had made several changes in the study design, statistical analysis, and implementation strategies delivery as outlined in the methods. METHODS: We originally proposed a two-arm, pragmatic, cluster, randomized hybrid implementation-effectiveness trial comparing two education strategies to improve NIV uptake in patients with severe COPD exacerbation in 20 hospitals with a low baseline rate of NIV use. Due to logistical constrains and slow recruitment, we changed the study design to an opened cohort stepped-wedge design with three steps which will allow the institutions to enroll when they are ready to participate. Only the IPE strategy will be implemented, and the education will be provided in an online virtual format. Our primary outcome will be the hospital-level risk-standardized NIV proportion for the period post-IPE training, along with the change in rate from the period prior to training. Aim 1 will compare the change over time of NIV use among patients with COPD in the step-wedged design. Aim 2 will explore the mediators\u27 role (respiratory therapist autonomy and team functionality) on the relationship between the implementation strategies and effectiveness. Finally, in Aim 3, through interviews with providers, we will assess the acceptability and feasibility of the educational training. CONCLUSION: The changes in study design will result in several limitation. Most importantly, the hospitals in the three cohorts are not randomized as they enroll based on their readiness. Second, the delivery of the IPE is virtual, and it is not known if remote education is conducive to team building. However, this study will be among the first to test the impact of IPE in the inpatient setting carefully and may generalize to other interventions directed to seriously ill patients. TRIAL REGISTRATION: ClinicalTrials.gov NCT04206735 . Registered on December 20, 2019

    Partial pressure of arterial carbon dioxide after resuscitation from cardiac arrest and neurological outcome: A prospective multi-center protocol-directed cohort study

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    Aims Partial pressure of arterial carbon dioxide (PaCO2) is a regulator of cerebral blood flow after brain injury. We sought to test the association between PaCO2 after resuscitation from cardiac arrest and neurological outcome. Methods A prospective protocol-directed cohort study across six hospitals. Inclusion criteria: age ≥ 18, non-traumatic cardiac arrest, mechanically ventilated after return of spontaneous circulation (ROSC), and receipt of targeted temperature management. Per protocol, PaCO2 was measured by arterial blood gas analyses at one and six hours after ROSC. We determined the mean PaCO2 over this initial six hours after ROSC. The primary outcome was good neurological function at hospital discharge, defined a priori as a modified Rankin Scale ≤ 3. Multivariable Poisson regression analysis was used to test the association between PaCO2 and neurological outcome. Results Of the 280 patients included, the median (interquartile range) PaCO2 was 44 (37-52) mmHg and 30% had good neurological function. We found mean PaCO2 had a quadratic (inverted “U” shaped) association with good neurological outcome, with a mean PaCO2 of 68 mmHg having the highest predictive probability of good neurological outcome, and worse neurological outcome at higher and lower PaCO2. Presence of metabolic acidosis attenuated the association between PaCO2 and good neurological outcome, with a PaCO2 of 51 mmHg having the highest predictive probability of good neurological outcome among patients with metabolic acidosis. Conclusion PaCO2 has a “U” shaped association with neurological outcome, with mild to moderate hypercapnia having the highest probability of good neurological outcome

    Association Between Elevated Mean Arterial Blood Pressure and Neurologic Outcome After Resuscitation From Cardiac Arrest: Results From a Multicenter Prospective Cohort Study

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    Objective: Laboratory studies suggest elevated blood pressure after resuscitation from cardiac arrest may be protective; however, clinical data are limited. We sought to test the hypothesis that elevated post-resuscitation mean arterial blood pressure (MAP) is associated with neurological outcome. Design: Pre-planned analysis of a prospective cohort study. Setting: Six academic hospitals in the United States. Patients: Adult, non-traumatic cardiac arrest patients treated with targeted temperature management after return of spontaneous circulation (ROSC). Interventions: MAP was measured non-invasively after ROSC and every hour during the initial six hours after ROSC. Measures and Main Results: We calculated the mean MAP and a priori dichotomized subjects into two groups: mean MAP 70–90 and > 90 mmHg. The primary outcome was good neurological function, defined as a modified Rankin Scale (mRS) ≤ 3. The mRS was prospectively determined at hospital discharge. Of the 269 patients included, 159 (59%) had a mean MAP > 90 mmHg. Good neurological function at hospital discharge occurred in 30% of patients in the entire cohort, and was significantly higher in patients with a mean MAP > 90 mmHg (42%) as compared to MAP 70–90 mmHg (15%) [absolute risk difference 27% (95% CI 17%−37%)]. In a multivariable Poisson regression model adjusting for potential confounders, mean MAP > 90 mmHg was associated with good neurological function, adjusted relative risk 2.46 (95% CI 2.09–2.88). Over ascending ranges of mean MAP, there was a dose-response increase in probability of good neurological outcome, with mean MAP > 110 mmHg having the strongest association, adjusted relative risk 2.97 (95% CI 1.86 – 4.76). Conclusions: Elevated blood pressure during the initial six hours after resuscitation from cardiac arrest was independently associated with good neurological function at hospital discharge. Further investigation is warranted to determine if targeting an elevated MAP would improve neurologic outcome after cardiac arrest

    Reducing neuroinflammation by delivery of IL‐10 encoding lentivirus from multiple‐channel bridges

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    The spinal cord is unable to regenerate after injury largely due to growth‐inhibition by an inflammatory response to the injury that fails to resolve, resulting in secondary damage and cell death. An approach that prevents inhibition by attenuating the inflammatory response and promoting its resolution through the transition of macrophages to anti‐inflammatory phenotypes is essential for the creation of a growth permissive microenvironment. Viral gene delivery to induce the expression of anti‐inflammatory factors provides the potential to provide localized delivery to alter the host inflammatory response. Initially, we investigated the effect of the biomaterial and viral components of the delivery system to influence the extent of cell infiltration and the phenotype of these cells. Bridge implantation reduces antigen‐presenting cell infiltration at day 7, and lentivirus addition to the bridge induces a transient increase in neutrophils in the spinal cord at day 7 and macrophages at day 14. Delivery of a lentivirus encoding IL‐10, an anti‐inflammatory factor that inhibits immune cell activation and polarizes the macrophage population towards anti‐inflammatory phenotypes, reduced neutrophil infiltration at both day 7 and day 28. Though IL‐10 lentivirus did not affect macrophages number, it skewed the macrophage population toward an anti‐inflammatory M2 phenotype and altered macrophage morphology. Additionally, IL‐10 delivery resulted in improved motor function, suggesting reduced secondary damage and increased sparing. Taken together, these results indicate that localized expression of anti‐inflammatory factors, such as IL‐10, can modulate the inflammatory response following spinal cord injury, and may be a key component of a combinatorial approach that targets the multiple barriers to regeneration and functional recovery.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/134909/1/btm210018.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/134909/2/btm210018_am.pd

    The immunologic effect of early intravenous two and four gram bolus dosing of tranexamic acid compared to placebo in patients with severe traumatic bleeding (TAMPITI): A randomized, double-blind, placebo-controlled, single-center trial

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    Background: The hemostatic properties of tranexamic acid (TXA) are well described, but the immunological effects of TXA administration after traumatic injury have not been thoroughly examined. We hypothesized TXA would reduce monocyte activation in bleeding trauma patients with severe injury. Methods: This was a single center, double-blinded, randomized controlled trial (RCT) comparing placebo to a 2 g or 4 g intravenous TXA bolus dose in trauma patients with severe injury. Fifty patients were randomized into each study group. The primary outcome was a reduction in monocyte activation as measured by human leukocyte antigen-DR isotype (HLA-DR) expression on monocytes 72 h after TXA administration. Secondary outcomes included kinetic assessment of immune and hemostatic phenotypes within the 72 h window post-TXA administration. Results: The trial occurred between March 2016 and September 2017, when data collection ended. 149 patients were analyzed (placebo, Conclusion: In trauma patients with severe injury, 4 g intravenous bolus dosing of TXA has minimal immunomodulatory effects with respect to leukocyte phenotypes and circulating cytokine levels. Clinical Trial Registration: www.ClinicalTrials.gov, identifier NCT02535949

    Integrating a health-related-quality-of-life module within electronic health records: a comparative case study assessing value added

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    <p>Abstract</p> <p>Background</p> <p>Health information technology (HIT) applications that incorporate point-of-care use of health-related quality of life (HRQL) assessments are believed to promote patient-centered interactions between seriously ill patients and physicians. However, it is unclear how willing primary care providers are to use such HRQL HIT applications. The specific aim of this study was to explore factors that providers consider when assessing the value added of an HRQL application for their geriatric patients.</p> <p>Methods</p> <p>Three case studies were developed using the following data sources: baseline surveys with providers and staff, observations of staff and patients, audio recordings of patient-provider interactions, and semi-structured interviews with providers and staff.</p> <p>Results</p> <p>The primary factors providers considered when assessing value added were whether the HRQL information from the module was (1) duplicative of information gathered via other means during the encounter; (2) specific enough to be useful and/or acted upon, and; (3) useful for enough patients to warrant time spent reviewing it for all geriatric patients. Secondary considerations included level of integration of the HRQL and EHR, impact on nursing workflow, and patient reluctance to provide HRQL information.</p> <p>Conclusions</p> <p>Health-related quality of life modules within electronic health record systems offer the potential benefit of improving patient centeredness and quality of care. However, the modules must provide benefits that are substantial and prominent in order for physicians to decide that they are worthwhile and sustainable. Implications of this study for future research include the identification of perceived "costs" as well as a foundation for operationalizing the concept of "usefulness" in the context of such modules. Finally, developers of these modules may need to make their products customizable for practices to account for variation in EHR capabilities and practice workflows.</p
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