2,401 research outputs found

    Inflight and ground-based simulation of handling qualities of very large airplanes in landing approach

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    Inflight and ground based simulation of Boeing 367-80 variable stability aircraft handling qualities during landing approac

    Identification of urban watershed units using remote multispectral sensing

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    Submitted to Office of Water Resources Research, U.S. Department of the Interior.Contains four aerial color photographs, secured to pages by means of glue.Includes bibliographical references.Completion report, OWRR project no. A-012-COLO

    Bioethics and the Brain

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    Microelectronics and medical imaging are bringing us closer to a world where mind reading is possible and blindness banished - but we may not want to live there. New ways of imaging the human brain and new developments in microelectronics are providing unprecedented capabilities for monitoring the brain in real time and even for controlling brain function. The technologies are novel, but some of the questions that they will raise are not. Electrical activity in the brain can reveal the contents of a person\u27s memory. New imaging techniques might allow physician to detect devastating diseases long before those diseases become clinically apparent. And researchers may one day find brain activity that correlates with behavior patterns such as tendencies toward alcoholism, aggression, pedophilia, or racism. But how reliable will the information be, how should it be used, and what will it do to our notion of privacy? Meanwhile, microelectronics is making access to the brain a two-way street. The same electrical stimulation technologies that allow some deaf people to hear could be fashioned to control behavior as well. What are the appropriate limits to the use of this technology? Ethicists are only now beginning to take note of these developments in neuroscience

    A randomized trial of fish oil omega-3 fatty acids on arterial health, inflammation, and metabolic syndrome in a young healthy population

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    BACKGROUND: Long chain omega-3 fatty acids from fish oils (O3) are known to have beneficial effects on a number of vascular risk factors in at-risk populations. The effects of a highly bioavailable emulsified preparation on an overweight young adult population are less well known. METHODS: Young adults, age 18–30, with body mass indices (BMIs) greater than 23 (average = 28.1) were administered 1.7 g of O3 per day (N = 30) or safflower oil placebo (N = 27) in an emulsified preparation (Coromega, Inc.) for 4 weeks in a double-blind randomized design. Blood was drawn and anthropometric measurements taken before and after dosing. Hemodynamic measures (central pulse wave velocity, augmentation index, and aortic systolic blood pressure), inflammatory cytokines (IL-6, IL-8, IL-10, and tumor necrosis factor-α), red blood cell and plasma phospholipid fatty acid profiles, fasting serum lipids, glucose, and C-reactive protein were measured. RESULTS: Red cell and plasma phospholipid eicosapentaenoic acid and docosahexaenoic acid concentrations increased over the four weeks of dosing in the O3 group. Dosing with O3 did not affect central pulse wave velocity, augmentation index, or aortic systolic blood pressure. None of the five American Heart Association metabolic syndrome components improved over the dosing period. None of the inflammatory cytokines, C-reactive protein, or lipids (total or LDL cholesterol) improved over the dosing period. CONCLUSIONS: No salutary effects of O3 were observed in hemodynamic, metabolic syndrome criteria or inflammatory markers as a result of this relatively short period of administration in this relatively overweight, but healthy young adult cohort

    Infrared Behaviour of Systems With Goldstone Bosons

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    We develop various complementary concepts and techniques for handling quantum fluctuations of Goldstone bosons.We emphasise that one of the consequences of the masslessness of Goldstone bosons is that the longitudinal fluctuations also have a diverging susceptibility characterised by an anomalous dimension (d2)(d-2) in space-time dimensions 2<d<42<d<4.In d=4d=4 these fluctuations diverge logarithmically in the infrared region.We show the generality of this phenomenon by providing three arguments based on i). Renormalization group flows, ii). Ward identities, and iii). Schwinger-Dyson equations.We obtain an explicit form for the generating functional of one-particle irreducible vertices of the O(N) (non)--linear σ\sigma--models in the leading 1/N approximation.We show that this incorporates all infrared behaviour correctly both in linear and non-linear σ\sigma-- models. Our techniques provide an alternative to chiral perturbation theory.Some consequences are discussed briefly.Comment: 28 pages,2 Figs, a new section on some universal features of multipion processes has been adde

    Three-Dimensional Quantum Percolation Studied by Level Statistics

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    Three-dimensional quantum percolation problems are studied by analyzing energy level statistics of electrons on maximally connected percolating clusters. The quantum percolation threshold \pq, which is larger than the classical percolation threshold \pc, becomes smaller when magnetic fields are applied, i.e., \pq(B=0)>\pq(B\ne 0)>\pc. The critical exponents are found to be consistent with the recently obtained values of the Anderson model, supporting the conjecture that the quantum percolation is classified onto the same universality classes of the Anderson transition. Novel critical level statistics at the percolation threshold is also reported.Comment: to appear in the May issue of J. Phys. Soc. Jp

    Teachers as writers: a systematic review

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    This paper is a critical literature review of empirical work from 1990-2015 on teachers as writers. It interrogates the evidence on teachers’ attitudes to writing, their sense of themselves as writers and the potential impact of teacher writing on pedagogy or student outcomes in writing. The methodology was carried out in four stages. Firstly, educational databases keyword searches located 438 papers. Secondly, initial screening identified 159 for further scrutiny, 43 of which were found to specifically address teachers’ writing identities and practices. Thirdly, these sources were screened further using inclusion/exclusion criteria. Fourthly, the 22 papers judged to satisfy the criteria were subject to in-depth analysis and synthesis. The findings reveal that the evidence base in relation to teachers as writers is not strong, particularly with regard to the impact of teachers’ writing on student outcomes. The review indicates that teachers have narrow conceptions of what counts as writing and being a writer and that multiple tensions exist, relating to low self-confidence, negative writing histories, and the challenge of composing and enacting teacher and writer positions in school. However, initial training and professional development programmes do appear to afford opportunities for reformulation of attitudes and sense of self as writer

    Systematic 1/N1/N corrections for bosonic and fermionic vector models without auxiliary fields

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    In this paper, colorless bilocal fields are employed to study the large NN limit of both fermionic and bosonic vector models. The Jacobian associated with the change of variables from the original fields to the bilocals is computed exactly, thereby providing an exact effective action. This effective action is shown to reproduce the familiar perturbative expansion for the two and four point functions. In particular, in the case of fermionic vector models, the effective action correctly accounts for the Fermi statistics. The theory is also studied non-perturbatively. The stationary points of the effective action are shown to provide the usual large NN gap equations. The homogeneous equation associated with the quadratic (in the bilocals) action is simply the two particle Bethe Salpeter equation. Finally, the leading correction in 1N1\over N is shown to be in agreement with the exact SS matrix of the model.Comment: 24 pages, uses REVTEX macros. Replaced with final version to appear in Phys. Rev.
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