868 research outputs found

    Dark with Excessive Bright: Gambling Tells and the Naming Taboo

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    Within sacred language the belief has existed that the personal name is an intrinsic part of oneself. As such, its revelation threatens exposure to powers that might undo its bearer. Smith considers the relation between the detection of tells in gambling and that of so-called true names. Strategies of concealment and detection that are basic to both tell-reading and true-naming are explored in relation to post-colonial theory\u27s insights into using light in order to hide things

    Souls/Soles of Signs Tell Totems and the Sphinx Wager

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    This paper develops a philosophy of play through an analysis of the foot wager of the Sphinx. Applying a construction of the cosmology of Plato along with a Socratic etymology of her riddle’s answer, it provides a reading of Sphingian contestation consistent with contemporary practices of deception found in modern games like poker. I argue that such deception is constitutive of the excessive illumination of signaling tells in games and that such excess, in turn, is indicative in allied political contexts of a covetous and acquisitive obsession with light. This theory makes use also of Ralph Ellison’s refiguring of Oedipal play as a theory of tyranny and serves as a riposte to the psychoanalytic idea of the Oedipus complex

    Small band gap superlattices as intrinsic long wavelength infrared detector materials

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    Intrinsic long wavelength (lambda greater than or equal to 10 microns) infrared (IR) detectors are currently made from the alloy (Hg, Cd)Te. There is one parameter, the alloy composition, which can be varied to control the properties of this material. The parameter is chosen to set the band gap (cut-off wavelength). The (Hg, Cd)Te alloy has the zincblend crystal structure. Consequently, the electron and light-hole effective masses are essentially inversely proportional to the band gap. As a result, the electron and light-hole effective masses are very small (M sub(exp asterisk)/M sub o approx. M sub Ih/M sub o approx. less than 0.01) whereas the heavy-hole effective mass is ordinary size (M sub hh(exp asterisk)/M sub o approx. 0.4) for the alloy compositions required for intrinsic long wavelength IR detection. This combination of effective masses leads to rather easy tunneling and relatively large Auger transition rates. These are undesirable characteristics, which must be designed around, of an IR detector material. They follow directly from the fact that (Hg, Cd)Te has the zincblend crystal structure and a small band gap. In small band gap superlattices, such as HgTe/CdTe, In(As, Sb)/InSb and InAs/(Ga,In)Sb, the band gap is determined by the superlattice layer thicknesses as well as by the alloy composition (for superlattices containing an alloy). The effective masses are not directly related to the band gap and can be separately varied. In addition, both strain and quantum confinement can be used to split the light-hole band away from the valence band maximum. These band structure engineering options can be used to reduce tunneling probabilities and Auger transition rates compared with a small band gap zincblend structure material. Researchers discuss the different band structure engineering options for the various classes of small band gap superlattices

    Detection of the spin character of Fe(001) surface states by scanning tunneling microscopy: A theoretical proposal

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    We consider the magnetic structure on the Fe(001) surface and theoretically study the scanning tunneling spectroscopy using a spin-polarized tip (SP-STM). We show that minority-spin surface states induce a strong bias dependence of the tunneling differential conductance which largely depends on the orientation of the magnetization in the SP-STM tip relative to the easy magnetization axis in the Fe(001) surface. We propose to use this effect in order to determine the spin character of the Fe(001) surface states. This technique can be applied also to other magnetic surfaces in which surface states are observed.Comment: 5 pages, 4 figure

    Spin noise of itinerant fermions

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    We develop a theory of spin noise spectroscopy of itinerant, noninteracting, spin-carrying fermions in different regimes of temperature and disorder. We use kinetic equations for the density matrix in spin variables. We find a general result with a clear physical interpretation, and discuss its dependence on temperature, the size of the system, and applied magnetic field. We consider two classes of experimental probes: 1. electron-spin-resonance (ESR)-type measurements, in which the probe response to a uniform magnetization increases linearly with the volume sampled, and 2. optical Kerr/Faraday rotation-type measurements, in which the probe response to a uniform magnetization increases linearly with the length of the light propagation in the sample, but is independent of the cross section of the light beam. Our theory provides a framework for interpreting recent experiments on atomic gases and conduction electrons in semiconductors and provides a baseline for identifying the effects of interactions on spin noise spectroscopy

    The dynamics of microbial growth

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    Strain-Induced Conduction Band Spin Splitting in GaAs from First Principles Calculations

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    We use a recently developed self-consistent GW approximation to present first principles calculations of the conduction band spin splitting in GaAs under [110] strain. The spin orbit interaction is taken into account as a perturbation to the scalar relativistic hamiltonian. These are the first calculations of conduction band spin splitting under deformation based on a quasiparticle approach; and because the self-consistent GW scheme accurately reproduces the relevant band parameters, it is expected to be a reliable predictor of spin splittings. We also discuss the spin relaxation time under [110] strain and show that it exhibits an in-plane anisotropy, which can be exploited to obtain the magnitude and sign of the conduction band spin splitting experimentally.Comment: 8 pages, 4 figures, 1 tabl

    Reversal of spin polarization in Fe/GaAs (001) driven by resonant surface states: First-principles calculations

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    A minority-spin resonant state at the Fe/GaAs(001) interface is predicted to reverse the spin polarization with voltage bias of electrons transmitted across this interface. Using a Green's function approach within the local spin density approximation we calculate spin-dependent current in a Fe/GaAs/Cu tunnel junction as a function of applied bias voltage. We find a change in sign of the spin polarization of tunneling electrons with bias voltage due to the interface minority-spin resonance. This result explains recent experimental data on spin injection in Fe/GaAs contacts and on tunneling magnetoresistance in Fe/GaAs/Fe magnetic tunnel junctions
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