47,999 research outputs found

    Power density measurements in the near field of the DSS 13 26-meter antenna

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    Power density measurements were made at Deep Space Station (DSS) 13 in the near field of the 26-m antenna to determine if radio frequency (rf) fields generated by the 20-kW transmitters could be responsible for the failure of three solid state rf amplifiers. These amplifiers are used in the Search for Extraterrestrial Intelligence (SETI) Radio Spectrum Surveillance System, which is currently located at the site. Measurements were made independently for one transmitter at 7150 MHz, and both transmitters together. Measurement results are tabulated and compared with predicted power densities under the measurement conditions. The results agree with the predictions within a factor of two. The predictions appear to give worst case values. Measurements indicated that amplifier failures are not attributable to the transmitter

    Radio frequency interference survey over the 1.0-10.4 GHz frequency range at the Goldstone-Venus Development Station

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    The results of a low sensitivity Radio Frequency Interference (RFI) survey carried out at the Venus Station of the Goldstone Communications Complex are reported. The data cover the spectral range from 1 GHz to 10.4 GHz with a 10-kHz instantaneous bandwidth. Frequency and power levels were observed using a sweep-frequency spectrum analyzer connected to a 1-m diameter antenna pointed at zenith. The survey was conducted from February 16, 1987 through February 24, 1987

    Electrolytically regenerative hydrogen-oxygen fuel cell Patent

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    Electrolytically regenerative hydrogen-oxygen fuel cell

    Observations of stratospheric source gas profiles during the Arctic winter

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    An international campaign was performed at ESRANGE rocket base, near Kiruna, Sweden (68 N) from January 4 to February 15 in order to investigate the Chemistry of Ozone in the Polar Stratosphere (CHEOPS). Within the framework of this campaign two sets of large stratospheric air samples were collected by means of a balloon borne cryogenic air sampler. The two balloons were launched on February 1, and February 10, 1988. At present the samples are analyzed in our laboratory for their contents of several long lived trace gases such as CH4, N2O, H2, CO2, CO and the major halocarbons CH3Cl, CFCl3, CF2Cl2, CCl4, CH3CCl3, and C2F3Cl3. The vertical profiles derived from these samples will be presented and compared with previous observations made in February 1987. The data will be discussed in view of the dynamical evolution of the Arctic polar vortex during this winter

    A psychoanalytic concept illustrated: Will, must, may, can — revisiting the survival function of primitive omnipotence

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    The author explores the linear thread connecting the theory of Freud and Klein, in terms of the central significance of the duality of the life and death instinct and the capacity of the ego to tolerate contact with internal and external reality. Theoretical questions raised by later authors, informed by clinical work with children who have suffered deprivation and trauma in infancy, are then considered. Theoretical ideas are illustrated with reference to observational material of a little boy who suffered deprivation and trauma in infancy. He was first observed in the middle of his first year of life while he was living in foster care, and then later at the age of two years and three months, when he had been living with his adoptive parents for more than a year

    Non-resonant Raman response of inhomogeneous structures in the electron doped ttt-t' Hubbard model

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    We calculate the non-resonant Raman response, the single particle spectra and the charge-spin configuration for the electron doped ttt-t' Hubbard model using unrestricted Hartree-Fock calculations. We discuss the similarities and differences in the response of homogeneous versus inhomogeneous structures. Metallic antiferromagnetism dominates in a large region of the UnU-n phase diagram but at high values of the on-site interaction and for intermediate doping values, inhomogeneous configurations are found with lower energy. This result is in contrast with the case of hole doped cuprates where inhomogeneities are found already at very low doping. The inhomogeneities found are in-phase stripes compatible with inelastic neutron scattering experiments. They give an incoherent background in the Raman response. The B2gB_{2g} signal can show a quasiparticle-like component even when no Fermi surface is found in the nodal direction.Comment: 8 pages, 10 figures, accepted for publication in Phys. Rev.

    Tunneling Spectroscopy and Vortex Imaging in Boron-Doped Diamond

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    We present the first scanning tunneling spectroscopy study of single-crystalline boron doped diamond. The measurements were performed below 100 mK with a low temperature scanning tunneling microscope. The tunneling density of states displays a clear superconducting gap. The temperature evolution of the order parameter follows the weak coupling BCS law with Δ(0)/kBTc1.74\Delta(0)/k_B T_c \simeq 1.74. Vortex imaging at low magnetic field also reveals localized states inside the vortex core that are unexpected for such a dirty superconductor.Comment: 4 pages, 4 figures, replaced with revised versio
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