2,488 research outputs found

    A Simulator Study of the Effectiveness of a Pilot's Indicator which Combined Angle of Attack and Rate of Change of Total Pressure as Applied to the Take-Off Rotation and Climbout of a Supersonic Transport

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    A simulator study has been made to determine the effectiveness of a single instrument presentation as an aid to the pilot in controlling both rotation and climbout path in take-off. The instrument was basically an angle-of-attack indicator, biased with a total-pressure-rate input as a means of suppressing the phugoid oscillation. Linearized six-degree-of-freedom equations of motion were utilized in simulating a hypothetical supersonic transport as the test vehicle. Each of several experienced pilots performed a number of simulated take-offs, using conventional flight instruments and either an angle-of-attack instrument or the combined angle-of-attack and total-pressure-rate instrument. The pilots were able to rotate the airplane, with satisfactory precision, to the 15 deg. angle of attack required for lift-off when using either an angle-of-attack instrument or the instrument which combined total-pressure-rate with angle of attack. At least 4 to 6 second-S appeared to be required for rotation to prevent overshoot, particularly with the latter instrument. The flight paths resulting from take-offs with simulated engine failures were relatively smooth and repeatable within a reasonably narrow band when the combined angle-of-attack and total-pressure-rate instrument presentation was used. Some of the flight paths resulting from take-offs with the same engine-failure conditions were very oscillatory when conventional instruments and an angle-of-attack instrument were used. The pilots considered the combined angle-of-attack and total- pressure-rate instrument a very effective aid. Even though they could, with sufficient practice, perform satisfactory climbouts after simulated engine failure by monitoring the conventional instruments and making correction based on their readings, it was much easier to maintain a smooth flight path with the single combined angle-of-attack and total-pressure-rate instrument

    Human Metaphase Chromosome Preparation for Scanning Electron Microscopy - A Consideration of Inherent Problems

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    Although the physical dimensions of chromosomes are such that they fall well within the spatial resolving power of scanning electron microscopes, results in the past have been disappointing. This is most likely due to limitations in preparative techniques, coupled with the initial necessity to separate the chromosomes from the remainder of the metaphase cell. Two approaches have been employed, a; to use a variety of isolation buffers which provide bulk chromosome preparations, b; to use metaphase spreads prepared essentially as for light microscopy and re-processed for SEM. In the former, wide variations in chromosome surface topography and fibre organisation arise according to the choice of isolation buffer, and mixed populations preclude individual chromosome identification. In the latter the shortcomings in preparation can be considered the air drying that occurs during the making of spreads, and the initial use of methanol/acetic acid fixation. In our view however, these limitations in preparation are more than compensated by the ability to identify individual chromosomes, resolve chromatin fibre organisation, and compare the structural changes produced by a variety of banding techniques. Using this technique we have established a structural basis for the differential staining patterns that result from G and C banding treatments

    Student Engagement

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    Over the past nine years, the Grace E. Harris Leadership Program has developed seven projects commonly grouped under the topic of Student Engagement. The projects reflect different approaches to school spirit generation, student retention, student mentoring and student financial aid. Of the seven projects that our team reviewed, six were implemented or partially implemented, as indicated by the *. It was not uncommon to see GEHLI team ideas incorporated into unrelated University initiative(s), basically achieving the goals of the project, but without the team involvement

    Magnetic Field Evolution in Merging Clusters of Galaxies

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    We present initial results from the first 3-dimensional numerical magnetohydrodynamical (MHD) simulations of magnetic field evolution in merging clusters of galaxies. Within the framework of idealized initial conditions similar to our previous work, we look at the gasdynamics and the magnetic field evolution during a major merger event in order to examine the suggestion that shocks and turbulence generated during a cluster/subcluster merger can produce magnetic field amplification and relativistic particle acceleration and, as such, may play a role in the formation and evolution of cluster-wide radio halos. The ICM, as represented by the equations of ideal MHD, is evolved self-consistently within a changing gravitational potential defined largely by the collisionless dark matter component represented by an N-body particle distribution. The MHD equations are solved by the Eulerian, finite-difference code, ZEUS. The particles are evolved by a standard particle-mesh (PM) code. We find significant evolution of the magnetic field structure and strength during two distinct epochs of the merger evolution.Comment: 21 pages, 7 figures, Figure 2 is color postscript. Accepted for publication in Ap

    Early twentieth-century Vogue, George Wolfe Plank and the "Freaks of Mayfair"

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    Vogue was one of the most influential fashion magazines of the twentieth century. In the 1920s its British edition, launched in 1916, became a focus for various forms of queer visual and cultural expression. The origins of the related ‘amusing style’, which delighted in camp display, can be traced to the romantic and artistic collaboration between the American artist George Wolfe Plank and the British writer E. F. Benson during World War One. The illustrations that Plank produced for Benson’s book of satirical sketches of life in London’s high society, The Freaks of Mayfair (1916), shed light on the camp images that Plank designed for the covers of both the American and British editions of the magazine. Therefore, Plank can be understood to have played a key role in the development of queer visual culture during the early twentieth century

    Patient-reported outcomes of periacetabular osteotomy from the prospective ANCHOR cohort study

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    BACKGROUND: Current literature describing the periacetabular osteotomy (PAO) is mostly limited to retrospective case series. Larger, prospective cohort studies are needed to provide better clinical evidence regarding this procedure. The goals of the current study were to (1) report minimum 2-year patient-reported outcomes (pain, hip function, activity, overall health, and quality of life), (2) investigate preoperative clinical and disease characteristics as predictors of clinical outcomes, and (3) report the rate of early failures and reoperations in patients undergoing contemporary PAO surgery. METHODS: A large, prospective, multicenter cohort of PAO procedures was established, and outcomes at a minimum of 2 years were analyzed. A total of 391 hips were included for analysis (79% of the patients were female, and the average patient age was 25.4 years). Patient-reported outcomes, conversion to total hip replacement, reoperations, and major complications were documented. Variables with a p value of ≤0.10 in the univariate linear regressions were included in the multivariate linear regression. The backward stepwise selection method was used to determine the final risk factors of clinical outcomes. RESULTS: Clinical outcome analysis demonstrated major clinically important improvements in pain, function, quality of life, overall health, and activity level. Increasing age and a body mass index status of overweight or obese were predictive of improved results for certain outcome metrics. Male sex and mild acetabular dysplasia were predictive of lesser improvements in certain outcome measures. Three (0.8%) of the hips underwent early conversion to total hip arthroplasty, 12 (3%) required reoperation, and 26 (7%) experienced a major complication. CONCLUSIONS: This large, prospective cohort study demonstrated the clinical success of contemporary PAO surgery for the treatment of symptomatic acetabular dysplasia. Patient and disease characteristics demonstrated predictive value that should be considered in surgical decision-making. LEVEL OF EVIDENCE: Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence

    A World Inscribed – Introduction

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    In 1900 or thereabouts, Lorina Bulwer, an inmate of the Great Yarmouth workhouse in the east of England, produced a remarkable and extremely long letter. It was embroidered on samples of different kinds of material which she had sewn together to form a scroll of multicoloured cloth, five metres long (Image 1.1). On her sampler scroll, Lorina stitched a rambling autobiography in which she spat out her anger at being confined to the workhouse, and more specifically to its female lunatic ward. She asserted her identity frequently, repeated her name many times and declared that she was free. Lorina Bulwer’s sampler reminds us of the importance of writing at all levels of society, for both intimate and public purposes as well as in the process of identity formation. It also demonstrates that writing is ubiquitous, and often uses unexpected materials and unorthodox technologies. In this book, we examine the importance of writing at different social levels in a range of historical contexts across the world. As in the case of Lorina Bulwer, the discussion will take account of writing’s institutional frameworks, its personal expressions and the range of material support it has adopted in past societies.info:eu-repo/semantics/publishedVersio
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