9,938 research outputs found

    The Initial-Value Problem of Spherically Symmetric Wyman Sector Nonsymmetric Gravitational Theory

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    We cast the four-dimensional field equations of the Nonsymmetric Gravitational Theory (NGT) into a form appropriate for numerical study. In doing so, we have restricted ourselves to spherically symmetric spacetimes, and we have kept only the Wyman sector of the theory. We investigate the well-posedness of the initial-value problem of NGT for a particular data set consisting of a pulse in the antisymmetric field on an asymptotically flat space background. We include some analytic results on the solvability of the initial-value problem which allow us to place limits on the regions of the parameter space where the initial-value problem is solvable. These results are confirmed by numerically solving the constraints.Comment: REVTeX 3.0 with epsf macros and AMS symbols, 18 pages, 9 figure

    Abelian Anomalies in Nonlocal Regularization

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    Nonlocal regularization of QED is shown to possess an axial anomaly of the same form as other regularization schemes. The Noether current is explicitly constructed and the symmetries are shown to be violated, whereas the identities constructed when one properly considers the contribution from the path integral measure are respected. We also discuss the barrier to quantizing the fully gauged chiral invariant theory, and consequences.Comment: 21 pages, UTPT-93-0

    Design and Fabrication of the NASA Decoupler Pylon for the F-16 Aircraft

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    The NASA Decoupler Pylon is a passive means of suppressing wing-store flutter. The feasibility of demonstrating this concept on the F-16 aircraft was established through model wind tunnel tests and analyses. As a result of these tests and studies a ship set of Decoupler Pylons was designed and fabricated for a flight test demonstration on the F-16 aircraft. Basic design criteria were developed during the analysis study pertaining to pylon pitch stiffness, alignment system requirements, and damping requirements. A design was developed which utilized an electrical motor for the pylon alignment system. The design uses a four pin, two link pivot design which results in a remote pivot located at the center of gravity of the store when the store is in the aligned position. The pitch spring was fabricated from a tapered constant stress cantilevered beam. The pylon has the same external lines as the existing production pylon and is designed to use a MAU-12 ejection rack which is the same as the one used with the production pylon. The detailed design and fabrication was supported with a complete ground test of the pylon prior to shipment to NASA

    Symptomatic adrenal insufficiency during inhaled corticosteroid treatment

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    Symptomatic adrenal insufficiency, presenting as hypoglycaemia or poor weight gain, may occur on withdrawal of corticosteroid treatment but has not previously been reported during inhaled corticosteroid treatment. This case series illustrates the occurence of clinically significant adrenal insufficiency in asthmatic children while patients were on inhaled corticosteroid treatment and the unexpected modes of presentation. General practitioners and paediatricians need to be aware that this unusual but acute serious complication may occur in patients treated

    Unstable Hadrons in Hot Hadron Gas in Laboratory and in the Early Universe

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    We study kinetic master equations for chemical reactions involving the formation and the natural decay of unstable particles in a thermal bath. We consider the decay channel of one into two particles, and the inverse process, fusion of two thermal particles into one. We present the master equations the evolution of the density of the unstable particles in the early Universe. We obtain the thermal invariant reaction rate using as an input the free space (vacuum) decay time and show the medium quantum effects on π+πρ\pi+\pi \leftrightarrow \rho reaction relaxation time. As another laboratory example we describe the K+KϕK+K \leftrightarrow \phi process in thermal hadronic gas in heavy-ion collisions. A particularly interesting application of our formalism is the π0γ+γ\pi^{0}\leftrightarrow \gamma +\gamma process in the early Universe. We also explore the physics of π±\pi^{\pm} and μ±\mu^{\pm} freeze-out in the Universe.Comment: 13 pages, 9 figures, published in Physical Review

    Electron tunneling detected by electrostatic force

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    Journal ArticleA method is introduced for measuring the tunneling of electrons between a specially fabricated scanning probe microscope tip and a surface. The technique is based upon electrostatic force detection of charge as it is transferred to and from a small (10217 F) electrically isolated metallic dot on the scanning probe tip. The methods for dot fabrication, charging, and discharging are described and electron tunneling to a sample surface is demonstrated

    Single electron tunneling to insulator surfaces detected by electrostatic force

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    Journal ArticleThe detection of single-electron tunneling events between a metallic scanning probe tip and an insulating surface is demonstrated by an electrostatic force method. When a voltage-biased oscillating atomic force microscopy tip is placed within tunneling range of the surface of an insulator, single-electron tunneling events are observed between the tip and electronic states at the surface. The events cause an abrupt reduction in cantilever oscillation amplitude, due to the instantaneous reduction of the force gradient at the tip. In most cases, only a single electron tunnels to or from the surface. Experimental data show that no physical contact is made during the tunneling events

    Instability induced tunneling and repeatable charge injection to SiO2 surfaces by electrostatic force microscopy

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    Journal ArticleThe dynamic response and stability of a voltage biased oscillating cantilever in the proximity of an insulating sample surface is investigated. As the tip approaches the sample surface, the cantilever can jump between two different oscillation modes. The jump is detected as an abrupt increase in the amplitude. This abrupt increase in amplitude can bring the tip into tunneling range of the sample surface and electrons can tunnel between the metallic tip and insulator surface. The electron tunneling decreases the electrostatic force and force gradient sensed by the cantilever. These changes reduce the oscillation amplitude, causing the cantilever to return to the original oscillation mode. The tunneling of tens of electrons from a metallic tip to a SiO2 surface is detected by measuring the electrostatic force between the tip and the sample. Manipulation of a small number of electrons can be achieved by changing the polarity of the voltage applied, allowing the injection and extraction of electrons to and from an insulator surface

    Mission description and in-flight operations of ERBE instruments on ERBS and NOAA 9 spacecraft, November 1984 - January 1986

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    Instruments of the Earth Radiation Budget Experiment (ERBE) are operating on three different Earth orbiting spacecrafts: the Earth Radiation Budget Satellite (ERBS), NOAA-9, and NOAA-10. An overview is presented of the ERBE mission, in-orbit environments, and instrument design and operational features. An overview of science data processing and validation procedures is also presented. In-flight operations are described for the ERBE instruments aboard the ERBS and NOAA-9. Calibration and other operational procedures are described, and operational and instrument housekeeping data are presented and discussed
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