1,888 research outputs found

    Giving Oral Expression Free Rein : Implications for Diversity of University Hate Speech Code

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    This paper uses history, law, and First Amendment theory to examine the concepts of political correctness, free speech, and hate speech in a search for a solution of how best to deal with hate speech incidents that occur in the university campus community. The paper notes the American tendency toward tyranny of the majority as noted by Alexis de Tocqueville in the 1830s and then proceeds to examine the double-edged sword of free speech. By guaranteeing freedom of speech we promote the right to shout down ethnic and other minority groups; by providing penalties against those who use it to shout others down we make society less free. This paper suggests a different answer: promote more speech expressed in community meetings conducted in an atmosphere that is safe and encouraging for all to express their views

    Semiconductor device for generating an oscillating voltage

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    A semiconductor device which displays an oscillating voltage due to the creation of charge domains which includes a plurality of semiconductor layers and at least two electrodes spaced from one another in the direction of the layers, an upper of which has a composition and/or dimensions predetermined so that a charge therein balances a depletion from a surface charge of the upper layer on application of a potential difference across said electrodes. The electrodes may be in contact solely with the upper layer. A method of manufacturing the device is also provided

    Does the 8−N8-N bonding rule break down in As2_2Se3_3 glass?

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    The local coordination numbers of As2_2Se3_3 glass were determined by a combination of anomalous x-ray scattering experiments, reverse Monte Carlo calculations, and {\it ab initio} molecular dynamics simulations. The well-known `8-NN bonding rule' proposed by Mott breaks down around the As atoms, exceeding the rule by 7--26%. An experimental prediction based on mean-field theory agrees with the present experimental and theoretical results. The fourfold coordinated As atoms likely form As-As wrong bond chains rather than ethan-like configurations, which is identified as the origin for the breakdown of the `8-NN bonding rule'.Comment: 6 pages, 6figures, 1table, submitted to Europhysics Letter

    Thurston's pullback map on the augmented Teichm\"uller space and applications

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    Let ff be a postcritically finite branched self-cover of a 2-dimensional topological sphere. Such a map induces an analytic self-map σf\sigma_f of a finite-dimensional Teichm\"uller space. We prove that this map extends continuously to the augmented Teichm\"uller space and give an explicit construction for this extension. This allows us to characterize the dynamics of Thurston's pullback map near invariant strata of the boundary of the augmented Teichm\"uller space. The resulting classification of invariant boundary strata is used to prove a conjecture by Pilgrim and to infer further properties of Thurston's pullback map. Our approach also yields new proofs of Thurston's theorem and Pilgrim's Canonical Obstruction theorem.Comment: revised version, 28 page

    Thurston equivalence of topological polynomials

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    We answer Hubbard's question on determining the Thurston equivalence class of ``twisted rabbits'', i.e. images of the ``rabbit'' polynomial under n-th powers of the Dehn twists about its ears. The answer is expressed in terms of the 4-adic expansion of n. We also answer the equivalent question for the other two families of degree-2 topological polynomials with three post-critical points. In the process, we rephrase the questions in group-theoretical language, in terms of wreath recursions.Comment: 40 pages, lots of figure

    Transformer Oil Passivation and Impact of Corrosive Sulphur

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    In recent years a significant volume of research has been undertaken in order to understand the recent failures in oil insulated power apparatus due to deposition of copper sulphide on the conductors and in the insulation paper. Dibenzyl Disulfide (DBDS) has been found to be the leading corrosive sulphur compound in the insulation oil [1]. The process of copper sulphide formation and the deposition in the paper is still being investigated, but a recently proposed method seems to be gaining some confidence [1]. This method suggests a two-step process; initially the DBDS and some oil soluble copper complexes are formed. Secondly the copper complexes are absorbed in the paper insulation, where they then decompose into copper sulphide [2]. The most commonly used mitigating technique for corrosive sulphur contaminated oil is passivation, normally using Irgamet 39 or 1, 2, 3-benzotriazole (BTA). The passivator is diluted into the oil to a concentration of around 100ppm, where it then reacts with the copper conductors to form a complex layer around the copper, preventing it from interacting with DBDS compounds and forming copper sulphide. This research project will investigate the electrical properties of HV transformers which have tested positive for corrosive sulphur, and the evolution of those properties as the asset degrades due to sulphur corrosion. Parallel to this the long term properties of transformers with passivated insulation oil will be analysed in order to understand the passivator stability and whether it is necessary to keep adding the passivator to sustain its performance. Condition monitoring techniques under investigation will include dielectric spectroscopy, frequency response analysis, recovery voltage method (aka interfacial polarisation) amongst others. Partial discharge techniques will not be investigated, as the voltage between the coil plates is low and therefore it will not contribute significantly to the overall insulation breakdown, in corrosive oil related faults [3]. The goal of this research is to establish key electrical properties in both passivated and non-passivated power transformers that demonstrate detectable changes as the equipment degrades due to the insulation oil being corrosive

    Discrete wavelength-locked external cavity laser

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    An external cavity laser (and method of generating laser light) comprising: a laser light source; means for collimating light output by the laser light source; a diffraction grating receiving collimated light; a cavity feedback mirror reflecting light received from the diffraction grating back to the diffraction grating; and means for reliably tuning the external cavity laser to discrete wavelengths

    Ursinus College Bulletin, Fall 1979

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    Being an alumnus: It\u27s an active role • Economics: It really means business • A first in forecasting • Forum for current events and culture • Church-college colloquium • Something new has been added • Continuing education continues to grow • College gets valuable volume • East meets West • Eilts honored • Fall Board meeting report • Homecoming: October 27, 1979 • News notes • Births • Marriages • Deathshttps://digitalcommons.ursinus.edu/new_bulletin/1025/thumbnail.jp

    Portable Multigas Monitors for International Space Station

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    The Environmental Health System (EHS) on International Space Station (ISS) includes portable instruments to measure various cabin gases that acutely impact crew health. These hand-held devices measure oxygen, carbon dioxide, carbon monoxide, hydrogen chloride and hydrogen cyanide. The oxygen and carbon dioxide units also serve to back up key functions of the Major Constituent Analyzers. Wherever possible, commercial off-the-shelf (COTS) devices are employed by EHS to save development and sustaining costs. COTS hardware designed for general terrestrial applications however has limitations such as no pressure compensation, limited life of the active sensor, calibration drift, battery issues, unpredictable vendor support and obsolescence. The EHS fleet (inflight and ground inventory) of instruments is both aging and dwindling in number. With the retirement of the US Space Shuttle, maintenance of on-orbit equipment becomes all the more difficult. A project is underway to search for gas monitoring technology that is highly reliable and stable for years. Tunable Diode Laser Spectroscopy (TDLS) seems to be the front-runner technology, but generally is not yet commercially available in portable form. NASA has fostered the development of TDLS through the Small Business Innovative Research (SBIR) program. A number of gases of interest to the aerospace and submarine communities can be addressed by TDLS including the list mentioned above plus hydrogen fluoride, ammonia and water (humidity). There are several different forms of TDLS including photoacoustic and direct absorption spectroscopy using various multipass cell geometries. This paper describes the history of portable gas monitoring on NASA spacecraft and provides a status of the development of TDLS based instruments. Planned TDLS flight experiments on ISS could lead both to operational use on ISS and important roles in future Exploration spacecraft and habitats
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