279 research outputs found

    Concentric differential gearing arrangement

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    Two input members and two concentric rotatable output members are interconnected by a planetary gear arrangement. The first input drives directly the first output. The second input engages a carrier having the planetary gears affixed thereto. Rotation of the carriage causes rotation of the central sun gear of the planetary gear system. The sun gear is journaled to the carriage and is drivingly connected to the second output through a direction reversing set of bevel gears. The first input drive member includes a ring gear drivingly connected to the planetary gears for driving the second output member in the same direction and by the same amount as the first output member. Motion of the first input results in equal motion of the two outputs while input motion of the second input results in movement of the second output relative to the first output. This device is useful where non-interacting two-axis control of remote gimbaled systems is required

    Mechanical planetary compensating drive system

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    Drive enables two concentric output shafts to be controlled independently or rotated as a unit. Possible uses are pointing and tracking devices, rotary camera shutters with variable light control, gimbal systems with yaw and pitch movement, spectrometer mirror scanning devices, etc

    Salvage and storage of infectious disease protein targets in the SSGCID high-throughput crystallization pathway using microfluidics

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    SSGCID protein crystals were salvaged and stored using the MPCS Plug Maker and CrystalCards when high-throughput traditional sitting-drop vapor diffusion initially failed

    Gestational age limits for abortion and cross-border reproductive care in Europe: a mixed-methods study

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    Objectives Little is known about the experiences of women who travel within Europe for abortion care from countries with relatively liberal laws. This paper aims to assess the primary reasons for travel among a sample of women who travelled from European countries with relatively liberal abortion laws to obtain abortion care mainly in the UK and the Netherlands. Design Multi-country, 5-year mixed methods study on barriers to legal abortion and travel for abortion. Setting UK, the Netherlands and Spain. Population or Sample We present quantitative data from 204 surveys, and qualitative data from 30 in-depth interviews with pregnant people who travelled to the UK, the Netherlands and Spain from countries where abortion is legal on broad grounds within specific gestational age (GA) limits. Methods Mixed-methods. Main outcome measures GA when presenting at abortion clinic, primary reason for abortion-related travel. Results Study participants overwhelmingly reported travelling for abortion because they had exceeded GA limits in their country of residence. Participants also reported numerous delays and barriers to receiving care. Conclusions Our findings highlight the need for policies that support access to abortion throughout pregnancy and illustrate that early access to it is necessary but not sufficient to meet people's reproductive health needs. Funding This study is funded by the European Research Council (ERC). Tweetable abstract This study shows that GA limits drive women from EU countries where abortion is legal to seek abortions abroad

    In situ data collection and structure refinement from microcapillary protein crystallization

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    In situ X-ray data collection has the potential to eliminate the challenging task of mounting and cryocooling often fragile protein crystals, reducing a major bottleneck in the structure determination process. An apparatus used to grow protein crystals in capillaries and to compare the background X-ray scattering of the components, including thin-walled glass capillaries against Teflon, and various fluorocarbon oils against each other, is described. Using thaumatin as a test case at 1.8 angstrom resolution, this study demonstrates that high-resolution electron density maps and refined models can be obtained from in situ diffraction of crystals grown in microcapillaries

    Time-Controlled Microfluidic Seeding in nL-Volume Droplets To Separate Nucleation and Growth Stages of Protein Crystallization

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    This paper describes a method of time-controlled seeding to separate the stages of nucleation and growth in protein crystallization using a microfluidic device

    Control parameterization for optimal control problems with continuous inequality constraints: New convergence results

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    Control parameterization is a powerful numerical technique for solving optimal control problems with general nonlinear constraints. The main idea of control parameterization is to discretize the control space by approximating the control by a piecewise-constant or piecewise-linear function, thereby yielding an approximate nonlinear programming problem. This approximate problem can then be solved using standard gradient-based optimization techniques. In this paper, we consider the control parameterization method for a class of optimal control problems in which the admissible controls are functions of bounded variation and the state and control are subject to continuous inequality constraints. We show that control parameterization generates a sequence of suboptimal controls whose costs converge to the true optimal cost. This result has previously only been proved for the case when the admissible controls are restricted to piecewise continuous functions
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