46,503 research outputs found

    Many Things in Parables: Extravagant Stories in New Community

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    Reviewed Book: Borsch, Frederick Houk, Bp. Many Things in Parables: Extravagant Stories in New Community. Philadelphia: Fortress Press, 1988

    Hunds Rule Theory for Heavy Fermion Superconductors

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    In this paper, a generalization of standard spin fluctuation theory is considered which takes into account orbital degeneracy effects which are critical for describing f electrons. This theory leads to an instability for a superconducting pair state which obeys Hunds rules. Such a state has L=5, S=1, and J=4. The degeneracy of this state is broken by crystalline effects, and realistic calculations for UPt3UPt_3 find a resultant pair state with Γ6\Gamma_6^- symmetry, consistent with current experimental constraints.Comment: revised manuscript, 15 pages (Plain TeX with macros), plus 1 postscript figur

    Copper Tellurium Oxides - A Playground for Magnetism

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    A variety of copper tellurium oxide minerals are known, and many of them exhibit either unusual forms of magnetism, or potentially novel spin liquid behavior. Here, I review a number of the more interesting materials with a focus on their crystalline symmetry and, if known, the nature of their magnetism. Many of these exist (so far) in mineral form only, and most have yet to have their magnetic properties studied. This means a largely unexplored space of materials awaits our exploration.Comment: Contribution to a dedicated issue of the Journal of Magnetism and Magnetic Materials in memory of Art Freema

    Zero torque gear head wrench

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    A gear head wrench particularly suited for use in applying torque to bolts without transferring torsional stress to bolt-receiving structures is introduced. The wrench is characterized by a coupling including a socket, for connecting a bolt head with a torque multiplying gear train, provided within a housing having an annulus concentrically related to the socket and adapted to be coupled with a spacer interposed between the bolt head and the juxtaposed surface of the bolt-receiving structure for applying a balancing counter-torque to the spacer as torque is applied to the bolt head whereby the bolt-receiving structure is substantially isolated from torsional stress. As a result of the foregoing, the operator of the wrench is substantially isolated from any forces which may be imposed

    The TAVERNS emulator: An Ada simulation of the space station data communications network and software development environment

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    The Space Station DMS (Data Management System) is the onboard component of the Space Station Information System (SSIS) that includes the computers, networks and software that support the various core and payload subsystems of the Space Station. TAVERNS (Test And Validation Environment for Remote Networked Systems) is a distributed approach for development and validation of application software for Space Station. The TAVERNS concept assumes that the different subsystems will be developed by different contractors who may be geographically separated. The TAVERNS Emulator is an Ada simulation of a TAVERNS on the ASD VAX. The software services described in the DMS Test Bed User's Manual are being emulated on the VAX together with simulations of some of the core subsystems and a simulation of the DCN. The TAVERNS Emulator will be accessible remotely from any VAX that can communicate with the ASD VAX

    A strong coupling critique of spin fluctuation driven charge order in underdoped cuprates

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    Charge order has emerged as a generic feature of doped cuprates, leading to important questions about its origin and its relation to superconductivity. Recent experiments on two classes of hole doped cuprates indicate a novel d-wave symmetry for the order. These were motivated by earlier spin fluctuation theoretical studies based on an expansion about hot spots in the Brillouin zone that indicated such order would be competitive with d-wave superconductivity. Here, we reexamine this problem by solving strong coupling equations in the full Brillouin zone. Our results find that bond-oriented order, as seen experimentally, is strongly suppressed, indicating that the charge order must have a different origin.Comment: 5 pages, 4 figures plus Supplemental material

    An Out of Sample Test for Granger Causality

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    Granger (1980) summarizes his personal viewpoint on testing for causality, and outlines what he considers to be a useful operational version of his original definition of causality (Granger (1969)), which he notes was partially alluded to in Wiener (1958). This operational version is based on a comparison of the 1-step ahead predictive ability of competing models. However, Granger concludes his discussion by noting that it is common practice to test for Granger causality using in-sample F-tests. The practice of using in-sample type Granger causality tests continues to be prevalent. In this paper we develop simple (nonlinear) out-of-sample predictive ability tests of the Granger non-causality null hypothesis. In addition, Monte Carlo experiments are used to investigate the finite sample properites of the test. An empirical illustration shows that the choice of in-sample versus out-of-sample Granger causality tests can crucially affect the conclusions about the predictive content of money for output.

    Constructing a Virtual Training Laboratory Using Intelligent Agents

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    This paper reports on the results and experiences of the Trilogy project; a collaborative project concerned with the development of a virtual research laboratory using intelligence agents. This laboratory is designed to support the training of research students in telecommunications traffic engineering. Training research students involves a number of basic activities. They may seek guidance from, or exchange ideas with, more experienced colleagues. High quality academic papers, books and research reports provide a sound basis for developing and maintaining a good understanding of an area of research. Experimental tools enable new ideas to be evaluated, and hypotheses tested. These three components-collaboration, information and experimentation- are central to any research activity, and a good training environment for research should integrate them in a seamless fashion. To this end, we describe the design and implementation of an agent-based virtual laboratory
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