26,325 research outputs found

    Development of a digital electronic rebalance loop for a dry tuned-rotor two degree-of-freedom gyroscope

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    Digital electronic rebalance loops were designed and implemented in brassboard form to capture both X and Y axes of the Kearfott Gyroflex. The loops were width-modulated binary types using a 614.4 kHz keying signal and a 2.4 kHz sample frequency. The loops were designed for a torquing rate of 2 deg/sec (70.6 mA torquing current) and a data resolution of 23.4 milli-arc-sec per data pulse. Design considerations, implementation details, and preliminary experimental results are presented

    Conrad, Efficiency, and the Varieties of Imperialism

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    Cataloged from PDF version of article.The article examines 18th century Polish novelist Joseph Conrad's fiction in relation to different conceptions of imperialism and capitalism. Topics covered include his attitude towards "Englishness," the value of efficiency and on the British "work ethic." Also analyzed are his representation of Russian and German imperialism in the political essays and the suggestion that his fiction undermines the opposition in his nonfiction writings between different types of imperialism

    Development and preliminary evaluation of a clinical guidance programme for the decision about prophylactic oophorectomy in women undergoing a hysterectomy

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    Objectives: To develop a decision analysis based and computerised clinical guidance programme (CGP) that provides patient specific guidance on the decision whether or not to undergo a prophylactic oophorectomy to reduce the risk of subsequent ovarian cancer and to undertake a preliminary pilot and evaluation. Subjects: Women who had already agreed to have a hysterectomy who otherwise had no ovarian pathology. Setting: Oophorectomy decision consultation at the outpatient or pre-admission clinic. Methods: A CGP was developed with advice from gynaecologists and patient groups, incorporating a set of Markov models within a decision analytical framework to evaluate the benefits of undergoing a prophylactic oophorectomy or not on the basis of quality adjusted life expectancy, life expectancy, and for varying durations of hormone replacement therapy. Sensitivity analysis and preliminary testing of the CGP were undertaken to compare its overall performance with established guidelines and practice. A small convenience sample of women invited to use the CGP were interviewed, the interviews were taped and transcribed, and a thematic analysis was undertaken. Results: The run time of the programme was 20 minutes, depending on the use of opt outs to default values. The CGP functioned well in preliminary testing. Women were able to use the programme and expressed overall satisfaction with it. Some had reservations about the computerised format and some were surprised at the specificity of the guidance given. Conclusions: A CGP can be developed for a complex healthcare decision. It can give evidence-based health guidance which can be adjusted to account for individual risk factors and reflects a patient’s own values and preferences concerning health outcomes. Future decision aids and support systems need to be developed and evaluated in a way which takes account of the variation in patients’ preferences for inclusion in the decision making process

    Development of a Low-Noise High Common-Mode-Rejection Instrumentation Amplifier

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    Several previously used instrumentation amplifier circuits were examined to find limitations and possibilities for improvement. One general configuration is analyzed in detail, and methods for improvement are enumerated. An improved amplifier circuit is described and analyzed with respect to common mode rejection and noise. Experimental data are presented showing good agreement between calculated and measured common mode rejection ratio and equivalent noise resistance. The amplifier is shown to be capable of common mode rejection in excess of 140 db for a trimmed circuit at frequencies below 100 Hz and equivalent white noise below 3.0 nv/square root of Hz above 1000 Hz

    The Length of an SLE - Monte Carlo Studies

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    The scaling limits of a variety of critical two-dimensional lattice models are equal to the Schramm-Loewner evolution (SLE) for a suitable value of the parameter kappa. These lattice models have a natural parametrization of their random curves given by the length of the curve. This parametrization (with suitable scaling) should provide a natural parametrization for the curves in the scaling limit. We conjecture that this parametrization is also given by a type of fractal variation along the curve, and present Monte Carlo simulations to support this conjecture. Then we show by simulations that if this fractal variation is used to parametrize the SLE, then the parametrized curves have the same distribution as the curves in the scaling limit of the lattice models with their natural parametrization.Comment: 18 pages, 10 figures. Version 2 replaced the use of "nu" for the "growth exponent" by 1/d_H, where d_H is the Hausdorff dimension. Various minor errors were also correcte

    Law and Its Limitations in the GATT Multilateral Trade System, by Oliver Long

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    Design of a Torque Current Generator for Strapdown Gyroscopes

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    The design, analysis, and experimental evaluation of an optimum performance torque current generator for use with strapdown gyroscopes, is presented. Among the criteria used to evaluate the design were the following: (1) steady-state accuracy; (2) margins of stability against self-oscillation; (3) temperature variations; (4) aging; (5) static errors drift errors, and transient errors, (6) classical frequency and time domain characteristics; and (7) the equivalent noise at the input of the comparater operational amplifier. The DC feedback loop of the torque current generator was approximated as a second-order system. Stability calculations for gain margins are discussed. Circuit diagrams are shown and block diagrams showing the implementation of the torque current generator are discussed

    Dynamics of fat and lean mass in refuelling migrant passerines measured using quantitative magnetic resonance

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    Although fat deposition during stopover in migrating passerine birds has been extensively studied, changes in lean mass during refuelling are not well understood. I used quantitative magnetic resonance (QMR) analysis to measure the deposition of fat and lean mass for both recaptured and single capture migrant passerines in spring and fall at Long Point, Ontario. Both the recapture analysis and single capture regression analysis indicated a substantial contribution of lean mass to overall increases in total body mass. Some of the variation in the relative deposition of fat and lean mass was explained by sex, age and season. I then used radio-telemetry and mark-recapture analysis to investigate whether QMR affects a bird’s magnetic compass or stopover duration. QMR had no effect on stopover duration and departure orientation of migrating Black-throated Blue Warblers. QMR slightly increased stopover duration in adult White-throated Sparrows in fall, but not in spring. My study demonstrates that lean mass deposition is substantial and dynamic, and that QMR is a safe and effective technology to study fuel deposition of migrant birds in the field
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