1,870 research outputs found

    Generation and Analysis of Streamwise Vortices from Vortex Tube Apparatus

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    A pressurized vortex tube is used to generate streamwise vortices in a wind tunnel and the resulting flow behavior is analyzed. The apparatus is intended to verify computational data from the AFRL by offering a method of conducting real-world counterpart experiments. The apparatus design process and other considered approaches are discussed. The vortex tube is operated at pressures of 20, 30 and 40 psi while the wind tunnel is operated at 3, 5, 10 and 20% capacity. Flow measurements are performed using particle image velocimetry to observe vortices and freestream interactions from which velocity and vorticity data is comparatively analyzed. Results indicate that vortex velocity greater than freestream flow velocity is a primary factor in maintaining vortex structures further downstream, while increased supply pressure and reduced freestream velocity also reduce vortex dissipation rate. A brief analysis of the vortex interaction with a downstream airfoil is presented to support future work

    The Effects of Initiating a 24-hour Fast with a Low Versus a High Carbohydrate Shake on pancreatic hormones in the Elderly: A Randomized Crossover Study

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    Begin PURPOSE: The aim of this study is to understand how the macronutrient composition of the fast-initiating meal influences glucose regulating hormones during, and 24-hours after a 24-hour fast in older, sedentary, and abdominally obese adults. Understanding these outcomes will inform fasting protocols such as time restricted eating and alternate day fasting, which offer potential long-term health benefits. METHODS: We had 16 participants (7 male, 9 female). Each participant completed two 24-hour fasts (water only). In random order, one fast began with a high carb/low fat (HC/LF) shake and the other with a low carbohydrate/high fat shake (LC/HF) (equal calorie, volume and fiber). Venous blood draws were taken at hours 0, 1, 24, and 48. Participants fasted for 24 hours under free living conditions. RESULTS: There was a significant condition by time interaction for insulin (F = 4.08, P \u3c 0.01), amylin (F = 3.34, P = 0.02) and glucagon (F = 7.93, P \u3c 0.01). One hour after the consumption of the pre-fast shakes the LC/HF shake resulted in lower insulin (P = 0.02), amylin (P = 0.01) and higher glucagon (P = 0.05) compared to the HC/LF shake. However, there was no difference between conditions for insulin, glucagon or amylin at 0, 24 or 48 hours. CONCLUSION: Starting a fast with a LC/HF meal reduces the insulin response and increases glucagon which is beneficial for the switching of metabolic fuels from glucose to fat oxidation. However, this difference between conditions in hormone concentrations was not sustained over the course of the fast, as values for both glucagon, amylin and insulin were similar between conditions by 24 hours

    The Clinical Sustainability Assessment Tool: Measuring organizational capacity to promote sustainability in healthcare

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    BACKGROUND: Few validated assessment tools are available to increase understanding and measure factors associated with sustainment of clinical practices, an increasingly recognized need among clinicians. We describe the development of the Clinical Sustainability Assessment Tool (CSAT), designed to assess factors that contribute to sustainable practices in clinical settings. METHODS: Sixty-four participants from clinical and research fields participated in concept mapping and were recruited to brainstorm factors that lead to sustained clinical practices. Once repeated factors were removed, participants sorted items based on similarity and rated them by importance and feasibility. Using concept mapping analyses, items were grouped into meaningful domains to develop an initial tool. We then recruited pilot sites and early adopters, for a total of 286 practicing clinicians, to pilot and evaluate the tool. Individuals were recruited from clinical settings across pediatric and adult medical and surgical subspecialties. The data were analyzed using confirmatory factor analysis (CFA) to test hypothesized subscale structure in the instrument. We used root mean square error of approximation (RMSEA) and the standardized root mean square residual (SRMR) to assess fit and thus the ability of CSAT to measure the identified domains. RESULTS: The concept mapping produced sorted statements that were edited into items that could be responded to, resulting in the creation of a tool with seven determinant domains and 47 items. The pilot and CFA testing resulted in a final CSAT instrument made up 35 items, five per domain. CFA results demonstrated very good fit of the seven domain structure of the CSAT (RMSEA = 0.049; SRMR = 0.049). Usability testing indicated the CSAT is brief, easy to use, easy to learn, and does not require extensive training. Additionally, the measure scored highly (18/20) on the Psychometric and Pragmatic Evidence Rating Scale (PAPERS). The seven final CSAT domains were engaged staff and leadership, engaged stakeholders, organizational readiness, workflow integration, implementation and training, monitoring and evaluation, and outcomes and effectiveness. CONCLUSIONS: The CSAT is a new reliable assessment tool which allows for greater practical and scientific understanding of contextual factors that enable sustainable clinical practices over time

    Recent range-wide demographic expansion in a Taiwan endemic montane bird, Steere's Liocichla (Liocichla steerii)

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    <p>Abstract</p> <p>Background</p> <p>The subtropical island of Taiwan is an area of high endemism and a complex topographic environment. Phylogeographic studies indicate that vicariance caused by Taiwan's mountains has subdivided many taxa into genetic phylogroups. We used mitochondrial DNA sequences and nuclear microsatellites to test whether the evolutionary history of an endemic montane bird, Steere's Liocichla (<it>Liocichla steerii</it>), fit the general vicariant paradigm for a montane organism.</p> <p>Results</p> <p>We found that while mountains appear to channel gene flow they are not a significant barrier for Steere's Liocichla. Recent demographic expansion was evident, and genetic diversity was relatively high across the island, suggesting expansion from multiple areas rather than a few isolated refugia. Ecological niche modeling corroborated the molecular results and suggested that populations of Steere's Liocichla are connected by climatically suitable habitat and that there was less suitable habitat during the Last Glacial Maximum.</p> <p>Conclusions</p> <p>Genetic and ecological niche modeling data corroborate a single history--Steere's Liocichla was at lower density during the Last Glacial Maximum and has subsequently expanded in population density. We suggest that such a range-wide density expansion might be an overlooked cause for the genetic patterns of demographic expansion that are regularly reported. We find significant differences among some populations in <it>F</it><sub><it>ST </it></sub>indices and an admixture analysis. Though both of these results are often used to suggest conservation action, we affirm that statistically significant results are not necessarily biologically meaningful and we urge caution when interpreting highly polymorphic data such as microsatellites.</p

    Defining the molecular pathology of pancreatic body and tail adenocarcinom

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    Background: Pancreatic ductal adenocarcinoma (PDAC) remains a dismal disease, with very little improvement in survival over the past 50 years. Recent large-scale genomic studies have improved understanding of the genomic and transcriptomic landscape of the disease, yet very little is known about molecular heterogeneity according to tumour location in the pancreas; body and tail PDACs especially tend to have a significantly worse prognosis. The aim was to investigate the molecular differences between PDAC of the head and those of the body and tail of the pancreas. Methods: Detailed correlative analysis of clinicopathological variables, including tumour location, genomic and transcriptomic data, was performed using the Australian Pancreatic Cancer Genome Initiative (APGI) cohort, part of the International Cancer Genome Consortium study. Results: Clinicopathological data were available for 518 patients recruited to the APGI, of whom 421 underwent genomic analyses; 179 of these patients underwent whole-genome and 96 RNA sequencing. Patients with tumours of the body and tail had significantly worse survival than those with pancreatic head tumours (12·1 versus 22·0 months; P = 0·001). Location in the body and tail was associated with the squamous subtype of PDAC. Body and tail PDACs enriched for gene programmes involved in tumour invasion and epithelial-to-mesenchymal transition, as well as features of poor antitumour immune response. Whether this is due to a molecular predisposition from the outset, or reflects a later time point on the tumour molecular clock, requires further investigation using well designed prospective studies in pancreatic cancer. Conclusion: PDACs of the body and tail demonstrate aggressive tumour biology that may explain worse clinical outcomes

    Sintered silver finite element modelling and reliability based design optimisation in power electronic module

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    This paper discusses the design for reliability of a sintered silver structure in a power electronic module based on the computational approach that composed of high fidelity analysis, reduced order modelling, numerical risk analysis, and optimisation. The methodology was demonstrated on sintered silver interconnect sandwiched between silicon carbide chip and copper substrate in a power electronic module. In particular, sintered silver reliability due to thermal fatigue material degradation is one of the main concerns. Thermo-mechanical behaviour of the power module sintered silver joint structure is simulated by finite element analysis for cyclic temperature loading profile in order to capture the strain distribution. The discussion was on methods for approximate reduced order modelling based on interpolation techniques using Kriging and radial basis functions. The reduced order modelling approach uses prediction data for the thermo-mechanical behaviour. The fatigue lifetime of the sintered silver interconnect and the warpage of the interconnect layer was particular interest in this study. The reduced order models were used for the analysis of the effect of design uncertainties on the reliability of the sintered silver layer. To assess the effect of uncertain design data, a method for estimating the variation of reliability related metrics namely Latin Hypercube sampling was utilised. The product capability indices are evaluated from the distributions fitted to the histogram resulting from Latin Hypercube sampling technique. A reliability based design optimisation was demonstrated using Particle Swarm Optimisation algorithm for constraint optimisation task consists of optimising two different characteristic performance metrics such as the thermo-mechanical plastic strain accumulation per cycle on the sintered layer and the thermally induced warpage

    A scoping review of de-implementation frameworks and models

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    BACKGROUND: Reduction or elimination of inappropriate, ineffective, or potentially harmful healthcare services and public health programs can help to ensure limited resources are used effectively. Frameworks and models (FM) are valuable tools in conceptualizing and guiding the study of de-implementation. This scoping review sought to identify and characterize FM that can be used to study de-implementation as a phenomenon and identify gaps in the literature to inform future model development and application for research. METHODS: We searched nine databases and eleven journals from a broad array of disciplines (e.g., healthcare, public health, public policy) for de-implementation studies published between 1990 and June 2020. Two raters independently screened titles and abstracts, and then a pair of raters screened all full text records. We extracted information related to setting, discipline, study design, methodology, and FM characteristics from included studies. RESULTS: The final search yielded 1860 records, from which we screened 126 full text records. We extracted data from 27 articles containing 27 unique FM. Most FM (n = 21) were applicable to two or more levels of the Socio-Ecological Framework, and most commonly assessed constructs were at the organization level (n = 18). Most FM (n = 18) depicted a linear relationship between constructs, few depicted a more complex structure, such as a nested or cyclical relationship. Thirteen studies applied FM in empirical investigations of de-implementation, while 14 articles were commentary or review papers that included FM. CONCLUSION: De-implementation is a process studied in a broad array of disciplines, yet implementation science has thus far been limited in the integration of learnings from other fields. This review offers an overview of visual representations of FM that implementation researchers and practitioners can use to inform their work. Additional work is needed to test and refine existing FM and to determine the extent to which FM developed in one setting or for a particular topic can be applied to other contexts. Given the extensive availability of FM in implementation science, we suggest researchers build from existing FM rather than recreating novel FM. REGISTRATION: Not registered

    Trends in qualitative research in language teaching since 2000

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    This paper reviews developments in qualitative research in language teaching since the year 2000, focusing on its contributions to the field and identifying issues that emerge. Its aims are to identify those areas in language teaching where qualitative research has the greatest potential and indicate what needs to be done to further improve the quality of its contribution. The paper begins by highlighting current trends and debates in the general area of qualitative research and offering a working definition of the term. At its core is an overview of developments in the new millennium based on the analysis of papers published in 15 journals related to the field of language teaching and a more detailed description, drawn from a range of sources, of exemplary contributions during that period. Issues of quality are also considered, using illustrative cases to point to aspects of published research that deserve closer attention in future work, and key publications on qualitative research practice are reviewed
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