2,743 research outputs found

    Aerodynamic characteristics of a large-scale semispan model with a swept wing and an augmented jet flap with hypermixing nozzles

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    The aerodynamic characteristics of the augmentor wing concept with hypermixing primary nozzles were investigated. A large-scale semispan model in the Ames 40- by 80-Foot Wind Tunnel and Static Test Facility was used. The trailing edge, augmentor flap system occupied 65% of the span and consisted of two fixed pivot flaps. The nozzle system consisted of hypermixing, lobe primary nozzles, and BLC slot nozzles at the forward inlet, both sides and ends of the throat, and at the aft flap. The entire wing leading edge was fitted with a 10% chord slat and a blowing slot. Outboard of the flap was a blown aileron. The model was tested statically and at forward speed. Primary parameters and their ranges included angle of attack from -12 to 32 degrees, flap angles of 20, 30, 45, 60 and 70 degrees, and deflection and diffuser area ratios from 1.16 to 2.22. Thrust coefficients ranged from 0 to 2.73, while nozzle pressure ratios varied from 1.0 to 2.34. Reynolds number per foot varied from 0 to 1.4 million. Analysis of the data indicated a maximum static, gross augmentation of 1.53 at a flap angle of 45 degrees. Analysis also indicated that the configuration was an efficient powered lift device and that the net thrust was comparable with augmentor wings of similar static performance. Performance at forward speed was best at a diffuser area ratio of 1.37

    Large-scale V/STOL testing

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    Several facets of large-scale testing of V/STOL aircraft configurations are discussed with particular emphasis on test experience in the Ames 40- by 80-Foot Wind Tunnel. Examples of powered-lift test programs are presented in order to illustrate tradeoffs confronting the planner of V/STOL test programs. Large-scale V/STOL wind-tunnel testing can sometimes compete with small-scale testing in the effort required (overall test time) and program costs because of the possibility of conducting a number of different tests with a single large-scale model where several small-scale models would be required. The benefits of both high- or full-scale Reynolds numbers, more detailed configuration simulation, and number and type of onboard measurements are studied

    Brain oscillatory activity as a biomarker of motor recovery in chronic stroke

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    In the present work, we investigated the relationship of oscillatory sensorimotor brain activity to motor recovery. The neurophysiological data of 30 chronic stroke patients with severe upper‐limb paralysis are the basis of the observational study presented here. These patients underwent an intervention including movement training based on combined brain–machine interfaces and physiotherapy of several weeks recorded in a double‐blinded randomized clinical trial. We analyzed the alpha oscillations over the motor cortex of 22 of these patients employing multilevel linear predictive modeling. We identified a significant correlation between the evolution of the alpha desynchronization during rehabilitative intervention and clinical improvement. Moreover, we observed that the initial alpha desynchronization conditions its modulation during intervention: Patients showing a strong alpha desynchronization at the beginning of the training improved if they increased their alpha desynchronization. Patients showing a small alpha desynchronization at initial training stages improved if they decreased it further on both hemispheres. In all patients, a progressive shift of desynchronization toward the ipsilesional hemisphere correlates significantly with clinical improvement regardless of lesion location. The results indicate that initial alpha desynchronization might be key for stratification of patients undergoing BMI interventions and that its interhemispheric balance plays an important role in motor recovery.Bundesministerium für Bildung und Forschung, Grant/Award Numbers: 13GW0053, 16SV7754; Deutsche Forschungsgemeinschaft; Deutscher Akademischer Austauschdienst, Grant/Award Number: 9156335

    The Vehicle, 1969, Vol. 11 no. 1

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    Vol. 11, No. 1 Table of Contents PhotoJeff Nelsonpage 4 The Dancing BodLukepage 5 The Hide-OutEleanor Aikenpage 6 DrawingLawrence Unfriedpage 7 Rain-Drunk Midnight ManiaThomas W. Reapage 9 What I\u27m Supposed To Say About WarMichael G. McKeepage 10 Sinking LashesThomas W. Reapage 10 CandleThomas W. Reapage 10 Nervous ChaperoneThomas W. Reapage 10 Formless Beauty Left To DryThomas W. Reapage 10 MasqueradeThomas W. Reapage 10 Mad JohnJames Jonespage 11 Black RacistJames Jonespage 12 HandsLawrence Unfriedpage 13 The Real Jonathan T. WillwickCharles Whitepage 14 A Cold Afternoon In JanuaryCharles Whitepage 16 Crumpled PaperLawrence Unfriedpage 16 ImpressionMichael G. McKeepage 18 The HunterMary Ann Spidelpage 19 PhotoJeff NelsonCaptionMichael G. McKeepage 20https://thekeep.eiu.edu/vehicle/1019/thumbnail.jp

    The Vehicle, 1969, Vol. 11 no. 1

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    Vol. 11, No. 1 Table of Contents PhotoJeff Nelsonpage 4 The Dancing BodLukepage 5 The Hide-OutEleanor Aikenpage 6 DrawingLawrence Unfriedpage 7 Rain-Drunk Midnight ManiaThomas W. Reapage 9 What I\u27m Supposed To Say About WarMichael G. McKeepage 10 Sinking LashesThomas W. Reapage 10 CandleThomas W. Reapage 10 Nervous ChaperoneThomas W. Reapage 10 Formless Beauty Left To DryThomas W. Reapage 10 MasqueradeThomas W. Reapage 10 Mad JohnJames Jonespage 11 Black RacistJames Jonespage 12 HandsLawrence Unfriedpage 13 The Real Jonathan T. WillwickCharles Whitepage 14 A Cold Afternoon In JanuaryCharles Whitepage 16 Crumpled PaperLawrence Unfriedpage 16 ImpressionMichael G. McKeepage 18 The HunterMary Ann Spidelpage 19 PhotoJeff NelsonCaptionMichael G. McKeepage 20https://thekeep.eiu.edu/vehicle/1019/thumbnail.jp

    Employee Stock Ownership and Financial Performance in European Countries: The Moderating Effects of Uncertainty Avoidance and Social Trust

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    This study investigates how the effect of employee stock ownership on financial performance may hinge on the diverse cultural and societal contexts of European countries. Based on agency and national culture theories, we hypothesize that the positive relationship between employee stock ownership and return on assets (ROA) is stronger in those nations with lower uncertainty avoidance and higher social trust. Using a multisource, time‐lagged, large‐scale dataset of 1,741 firms from 21 countries in Europe, our multilevel, random coefficient modeling analysis found evidence for these hypotheses, suggesting that uncertainty avoidance and social trust serve as important contextual cues in predicting the linkage between employee stock ownership and financial performance. Our supplemental analysis with distinction between the managerial and nonmanagerial employee stock ownership further indicates managerial employee stock ownership has a direct positive effect on ROA. Although nonmanagerial employee stock ownership had a nonsignificant association with ROA, the relationship was positive and significant when uncertainty avoidance was low and social trust was high. This research contributes to the existing literature by illuminating some of the contextual influences altering the effectiveness of employee stock ownership. Our findings also offer practical suggestions for effectively using employee stock ownership

    The role of academic mentors for Latino/a adolescents exposed to community violence

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    AimsWe examined the protective role of academic mentors for Latino/a youth exposed to community violence. We tested whether the mentor facilitation of positive growth and mentor school involvement moderated the relations between exposure to violence and Latino/a youth’s educational values, school effort, and academic efficacy.MethodsWe used hierarchical linear regressions to examine these relations among 210 Latino/a high school students.ResultsWitnessing violence and personal victimization was negatively related to all three educational outcomes. Mentor school involvement was positively related to all three educational outcomes, whereas mentor facilitation of growth was positively related to educational values only. A significant interaction between witnessing violence and mentor school involvement indicated that the negative relation between witnessing violence and educational values weakened at high levels of mentor school involvement.ConclusionWe discuss the benefits of academic mentoring and exploring effective mentoring characteristics with Latino/a youth exposed to violence.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/150558/1/jcop22189_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/150558/2/jcop22189.pd

    A synthesis of the environmental response of the North and South Atlantic Sub-Tropical Gyres during two decades of AMT

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    This is the author accepted manuscript. The final version is available from Elsevier via the DOI in this record.Anthropogenically-induced global warming is expected to decrease primary productivity in the subtropical oceans by strengthening stratification of the water column and reducing the flux of nutrients from deep-waters to the sunlit surface layers. Identification of such changes is hindered by a paucity of long-term, spatially-resolved, biological time-series data at the basin scale. This paper exploits Atlantic Meridional Transect (AMT) data on physical and biogeochemical properties (1995–2014) in synergy with a wide range of remote-sensing (RS) observations from ocean colour, Sea Surface Temperature (SST), Sea Surface Salinity (SSS) and altimetry (surface currents), combined with different modelling approaches (both empirical and a coupled 1-D Ecosystem model), to produce a synthesis of the seasonal functioning of the North and South Atlantic Sub-Tropical Gyres (STGs), and assess their response to longer-term changes in climate. We explore definitive characteristics of the STGs using data of physical (SST, SSS and peripheral current systems) and biogeochemical variables (chlorophyll and nitrate), with inherent criteria (permanent thermal stratification and oligotrophy), and define the gyre boundary from a sharp gradient in these physical and biogeochemical properties. From RS data, the seasonal cycles for the period 1998–2012 show significant relationships between physical properties (SST and PAR) and gyre area. In contrast to expectations, the surface layer chlorophyll concentration from RS data (CHL) shows an upward trend for the mean values in both subtropical gyres. Furthermore, trends in physical properties (SST, PAR, gyre area) differ between the North and South STGs, suggesting the processes responsible for an upward trend in CHL may vary between gyres. There are significant anomalies in CHL and SST that are associated with El Niño events. These conclusions are drawn cautiously considering the short length of the time-series (1998–2012), emphasising the need to sustain spatially-extensive surveys such as AMT and integrate such observations with models, autonomous observations and RS data, to help address fundamental questions about how our planet is responding to climate change. A small number of dedicated AMT cruises in the keystone months of January and July would complement our understanding of seasonal cycles in the STGs.Natural Environment Research Council National CapabilityUK National Centre for Earth Observatio

    Accessory renal arteries in a Caribbean population: a computed tomography based study

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    INTRODUCTION: The commonest variation to the classic anatomic description of renal arterial supply is the presence of accessory renal arteries. The incidence varies widely according to ethnicity. There is no data on the prevalence of these anomalies in persons of Caribbean ethnicity. METHODS: All CT scans done over two years from July 1, 2010 to June 30, 2012 were retrospectively evaluated. The anatomy of the renal arterial supply was reported from these studies and the anatomy of accessory renal arteries was documented. RESULTS: There were 302 CT scans evaluated and accessory renal arteries were present in 109/302 (36.1%) CT scans, 95% confidence interval 30.6%, 41.4%. There were 71/309 (23.5%) patients with accessory arteries on the left and 54/309 (17.9%) had them on the right (p 0.087). Of these, 16 (14.7%) patients had bilateral accessory renal arteries present. The most common origin for the accessory arteries was the abdominal aorta in 108 (99.1%) cases and in 1 case the accessory artery arose from the coeliac trunk. There were 80 left sided accessory renal arteries: 17 (21.3%) upper polar and 27 (33.8%) lower polar arteries. Of 62 right sided accessory arteries, 14 (22.6%) were upper polar and 26 (42%) were lower polar arteries. CONCLUSION: This is the first population-based report of anatomic anomalies in renal arterial supply in a Caribbean population. These are important findings that may affect vascular and urologic procedures on persons of Caribbean ethnicity

    Towards a ‘Long View’: Historical Perspectives on the Scaling and Replication of Social Ventures

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    Social ventures are now widely regarded as playing an essential role in addressing persistent and pervasive societal challenges. This insight has prompted an active search for readily-scaleable and replicable business models. However, relatively little consideration has been given to the longer-term growth and performance of these hybrid organizational forms. This paper examines how historically-informed research might enhance our understanding of growth processes. It considers the conceptualization of organizational growth in social ventures and the relevance of prevailing constructs. The explanatory potential of ‘long view’ approaches examined by applying three constructs, opportunity recognition, entrepreneurial adjustment, and institutional structure, in a comparative historical analysis of two British social ventures
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