1,079 research outputs found

    Method of vibration isolating an aircraft engine

    Get PDF
    A method for coupling an engine to a support frame for mounting to a fuselage of an aircraft using a three point vibration isolating mounting system in which the load reactive forces at each mounting point are statically and dynamically determined. A first vibration isolating mount pivotably couples a first end of an elongated support beam to a stator portion of an engine with the pivoting action of the vibration mount being oriented such that it is pivotable about a line parallel to a center line of the engine. An aft end of the supporting frame is coupled to the engine through an additional pair of vibration isolating mounts with the mounts being oriented such that they are pivotable about a circumference of the engine. The aft mounts are symmetrically spaced to each side of the supporting frame by 45 degrees. The relative orientation between the front mount and the pair of rear mounts is such that only the rear mounts provide load reactive forces parallel to the engine center line, in support of the engine to the aircraft against thrust forces. The forward mount is oriented so as to provide only radial forces to the engine and some lifting forces to maintain the engine in position adjacent a fuselage. Since each mount is connected to provide specific forces to support the engine, forces required of each mount are statically and dynamically determinable

    Voting and the Cardinal Aggregation of Judgments

    Get PDF
    The paper elaborates the idea that voting is an instance of the aggregation of judgments, this being a more general concept than the aggregation of preferences. To aggregate judgments one must first measure them. I show that such aggregation has been unproblematic whenever it has been based on an independent and unrestricted scale. The scales analyzed in voting theory are either context dependent or subject to unreasonable restrictions. This is the real source of the diverse 'paradoxes of voting' that would better be termed 'voting pathologies'. The theory leads me to advocate what I term evaluative voting. It can also be called utilitarian voting as it is based on having voters express their cardinal preferences. The alternative that maximizes the sum wins. This proposal operationalizes, in an election context, the abstract cardinal theories of collective choice due to Fleming and Harsanyi. On pragmatic grounds, I argue for a three valued scale for general elections

    The Chicken Yolk Sac IgY Receptor, a Mammalian Mannose Receptor Family Member, Transcytoses IgY across Polarized Epithelial Cells

    Get PDF
    In mammals the transfer of passive immunity from mother to young is mediated by the MHC-related receptor FcRn, which transports maternal IgG across epithelial cell barriers. In birds, maternal IgY in egg yolk is transferred across the yolk sac to passively immunize chicks during gestation and early independent life. The chicken yolk sac IgY receptor (FcRY) is the ortholog of the mammalian phospholipase A2 receptor, a mannose receptor family member, rather than an FcRn or MHC homolog. FcRn and FcRY both exhibit ligand binding at the acidic pH of endosomes and ligand release at the slightly basic pH of blood. Here we show that FcRY expressed in polarized mammalian epithelial cells functioned in endocytosis, bidirectional transcytosis, and recycling of chicken FcY/IgY. Confocal immunofluorescence studies demonstrated that IgY binding and endocytosis occurred at acidic but not basic pH, mimicking pH-dependent uptake of IgG by FcRn. Colocalization studies showed FcRY-mediated internalization via clathrin-coated pits and transport involving early and recycling endosomes. Disruption of microtubules partially inhibited apical-to-basolateral and basolateral-to-apical transcytosis, but not recycling, suggesting the use of different trafficking machinery. Our results represent the first cell biological evidence of functional equivalence between FcRY and FcRn and provide an intriguing example of how evolution can give rise to systems in which similar biological requirements in different species are satisfied utilizing distinct protein folds

    Stability of narrow beams in bulk Kerr-type nonlinear media

    Full text link
    We consider (2+1)-dimensional beams, whose transverse size may be comparable to or smaller than the carrier wavelength, on the basis of an extended version of the nonlinear Schr\"{o}dinger equation derived from the Maxwell`s equations. As this equation is very cumbersome, we also study, in parallel to it, its simplified version which keeps the most essential term: the term which accounts for the {\it nonlinear diffraction}. The full equation additionally includes terms generated by a deviation from the paraxial approximation and by a longitudinal electric-field component in the beam. Solitary-wave stationary solutions to both the full and simplified equations are found, treating the terms which modify the nonlinear Schr\"{o}dinger equation as perturbations. Within the framework of the perturbative approach, a conserved power of the beam is obtained in an explicit form. It is found that the nonlinear diffraction affects stationary beams much stronger than nonparaxiality and longitudinal field. Stability of the beams is directly tested by simulating the simplified equation, with initial configurations taken as predicted by the perturbation theory. The numerically generated solitary beams are always stable and never start to collapse, although they display periodic internal vibrations, whose amplitude decreases with the increase of the beam power.Comment: 7 pages, 6 figures Accepted for publication in PR

    Evanescent light-matter Interactions in Atomic Cladding Wave Guides

    Full text link
    Alkali vapors, and in particular rubidium, are being used extensively in several important fields of research such as slow and stored light non-linear optics3 and quantum computation. Additionally, the technology of alkali vapors plays a major role in realizing myriad industrial applications including for example atomic clocks magentometers8 and optical frequency stabilization. Lately, there is a growing effort towards miniaturizing traditional centimeter-size alkali vapor cells. Owing to the significant reduction in device dimensions, light matter interactions are greatly enhanced, enabling new functionalities due to the low power threshold needed for non-linear interactions. Here, taking advantage of the mature Complimentary Metal-Oxide-Semiconductor (CMOS) compatible platform of silicon photonics, we construct an efficient and flexible platform for tailored light vapor interactions on a chip. Specifically, we demonstrate light matter interactions in an atomic cladding wave guide (ACWG), consisting of CMOS compatible silicon nitride nano wave-guide core with a Rubidium (Rb) vapor cladding. We observe the highly efficient interaction of the electromagnetic guided mode with the thermal Rb cladding. The nature of such interactions is explained by a model which predicts the transmission spectrum of the system taking into account Doppler and transit time broadening. We show, that due to the high confinement of the optical mode (with a mode area of 0.3{\lambda}2), the Rb absorption saturates at powers in the nW regime.Comment: 10 Pages 4 Figures. 1 Supplementar

    Web- and app-based tools for remote hearing assessment: a scoping review

    Get PDF
    Objective: Remote hearing screening and assessment may improve access to, and uptake of, hearing care. This review, the most comprehensive to date, aimed to (i) identify and assess functionality of remote hearing assessment tools on smartphones and online platforms, (ii) determine if assessed tools were also evaluated in peer-reviewed publications and (iii) report accuracy of existing validation data. Design: Protocol was registered in INPLASY and reported according to PRISMA-Extension for Scoping Reviews. Study sample: In total, 187 remote hearing assessment tools (using tones, speech, self-report or a combination) and 101 validation studies met the inclusion criteria. Quality, functionality, bias and applicability of each app were assessed by at least two authors. Results: Assessed tools showed considerable variability in functionality. Twenty-two (12%) tools were peer-reviewed and 14 had acceptable functionality. The validation results and their quality varied greatly, largely depending on the category of the tool. Conclusion: The accuracy and reliability of most tools are unknown. Tone-producing tools provide approximate hearing thresholds but have calibration and background noise issues. Speech and self-report tools are less affected by these issues but mostly do not provide an estimated pure tone audiogram. Predicting audiograms using filtered language-independent materials could be a universal solution

    Desorption of hot molecules from photon irradiated interstellar ices

    Get PDF
    We present experimental measurements of photodesorption from ices of astrophysical relevance. Layers of benzene and water ice were irradiated with a laser tuned to an electronic transition in the benzene molecule. The translational energy of desorbed molecules was measured by time-of-flight (ToF) mass spectrometry. Three distinct photodesorption processes were identified - a direct adsorbate-mediated desorption producing benzene molecules with a translational temperature of around 1200 K, an indirect adsorbate-mediated desorption resulting in water molecules with a translational temperature of around 450 K, and a substrate-mediated desorption of both benzene and water producing molecules with translational temperatures of around 530 K and 450 K respectively. The translational temperature of each population of desorbed molecules is well above the temperature of the ice matrix. The implications for gas-phase chemistry in the interstellar medium are discussed.Comment: 23 pages, including 4 figures; submitted to Ap

    Supporting the Inclusion of Socially Vulnerable Early Adolescents: Theory and Illustrations of the BASE Model

    Get PDF
    We focus on the inclusion of socially vulnerable early adolescents including students with special education needs (SEN). Building from multiple intervention and randomized control trials of a professional development model aimed at supporting teachers\u27 management of the classroom social context, we provide an overview of the Behavioral, Academic, and Social Engagement (BASE) Model as a framework to foster social inclusion. We briefly review the conceptual foundations of this model and we present the delivery (i.e., directed consultation, the scouting report process) and content (i.e., Academic Engagement Enhancement, Competence Enhancement Behavior Management, Social Dynamics Management) components of BASE. We then briefly discuss the intervention support needs of subtypes of socially vulnerable youth and how these needs can be differentially addressed within the BASE framework. Many students are concerned about social difficulties during the late elementary and middle school years (Graham et al., 2006; Rice et al., 2011). This is particularly true for early adolescents with special education needs (SEN) who are at increased risk for peer rejection, social isolation, and involvement in peer victimization (Frederickson and Furnham, 2004; Estell et al., 2009a; Sullivan et al., 2015). The Behavioral, Academic, and Social Engagement (BASE) Model was developed as a holistic, ecological classroom management approach that teachers can use to support socially vulnerable youth during the transition to middle school. Our goal is to describe the application of the BASE model for supporting the inclusion of distinct subtypes of students with SEN during the late childhood and early adolescent school years. We address five aims. We begin with an overview of the social inclusion of students with SEN. Then, we build upon a person-in context dynamic systems perspective to describe the theoretical foundations of the BASE model. Next, we summarize the intervention components and practice elements of the BASE model and their linkages to key social development process variables typically experienced by early adolescents. Building on research using latent profile analysis of interpersonal competence, we discuss three distinct configurations or subtypes of socially vulnerable youth: popular aggressive; passive; and low-adaptive (i.e., multi-risk). Finally, using these configurations and associated adjustment factors as a guide, we illustrate how teachers can use the BASE model to adapt strategies and supports for each subtype. We focus on how teachers need to be attuned not only to the differential needs of sub-types of youth, but to also be aware that their management of the classroom experience of students characterized by different configurations may contribute to how subtypes of students are perceived by their classmates and their corresponding relationships and social roles in the peer ecology

    'Don't think in your head, think aloud': ICT and exploratory talk in the primary school mathematics classroom

    Get PDF
    This paper arises out of research into classroom activities conducted with Year 5 and Year 6 primary school students (9-10 year-olds). The study applied the ‘Thinking Together’ approach developed by Mercer and colleagues at the Open University in mathematics lessons involving the use of ICT. The study describes the use of mathematics software to promote collaborative thinking and exploratory talk in the mathematics classroom. Teachers were given training in the Thinking Together approach. They then conducted a series of lessons with students and explicitly taught them how to work and talk collaboratively to solve mathematical problems at the computer. These lessons were video-recorded and the transcripts analysed for evidence of ‘exploratory talk’. This paper reports on the role of the teacher, the students and the computer in developing exploratory talk
    • …
    corecore