14,516 research outputs found

    Some results concerning the principal airglow lines as measured from the OGO-II satellite

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    OGO-II satellite measurement of principal airglow line

    The global characteristics of atmosphere emissions in the lower thermosphere and their aeronomic implications

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    The green line of atomic oxygen and the Herzberg bands of molecular oxygen as observed from the OGO-4 airglow photometer are discussed in terms of their spatial and temporal distributions and their relation to the atomic oxygen content in the lower thermosphere. Daily maps of the distribution of emissions show considerable structure (cells, patches, and bands) with appreciable daily changes. When data are averaged over periods of several days in length, the resulting patterns have occasional tendencies to follow geomagnetic parallels. The Seasonal variations are characterized by maxima in both the Northern and Southern Hemispheres in October, with the Northern Hemisphere having substantially higher emission rates. Formulae are derived relating the vertical column emission rates of the green line and the Herzberg bands to the atomic oxygen peak density. Global averages for the time period for these data (August 1967 to January 1968), when converted to maximum atomic oxygen densities near 95 km, have a range of 2.0 x 10 to the 11th power/cu cm 2.7 x 10 to the 11th power/cu cm

    A night-time measurement of ozone above 40 km

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    Night-time photometer measurements of ozone concentration at high altitud

    Behavior of the sodium and hydroxyl nighttime emissions during a stratospheric warming

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    The behavior of the sodium and hydroxyl nighttime emissions during a stratospheric warming has been studied principally by use of data from the airglow photometers on the OGO-4 satellite. It was found that during the late stages of a major warming, both emissions increase appreciably, with the sodium emission returning to normal levels prior to the decrease in hydroxyl emission. The emission behaviors are attributed to temperature and density variations from 70 to 94 km, and a one-dimensional hydrostatic model for that altitude range is used to calculate the effects on the emissions and on the mesospheric ozone densities

    Analytic structure of Bloch functions for linear molecular chains

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    This paper deals with Hamiltonians of the form H=-{\bf \nabla}^2+v(\rr), with v(\rr) periodic along the zz direction, v(x,y,z+b)=v(x,y,z)v(x,y,z+b)=v(x,y,z). The wavefunctions of HH are the well known Bloch functions \psi_{n,\lambda}(\rr), with the fundamental property ψn,λ(x,y,z+b)=λψn,λ(x,y,z)\psi_{n,\lambda}(x,y,z+b)=\lambda \psi_{n,\lambda}(x,y,z) and zψn,λ(x,y,z+b)=λzψn,λ(x,y,z)\partial_z\psi_{n,\lambda}(x,y,z+b)=\lambda \partial_z\psi_{n,\lambda}(x,y,z). We give the generic analytic structure (i.e. the Riemann surface) of \psi_{n,\lambda}(\rr) and their corresponding energy, En(λ)E_n(\lambda), as functions of λ\lambda. We show that En(λ)E_n(\lambda) and ψn,λ(x,y,z)\psi_{n,\lambda}(x,y,z) are different branches of two multi-valued analytic functions, E(λ)E(\lambda) and ψλ(x,y,z)\psi_\lambda(x,y,z), with an essential singularity at λ=0\lambda=0 and additional branch points, which are generically of order 1 and 3, respectively. We show where these branch points come from, how they move when we change the potential and how to estimate their location. Based on these results, we give two applications: a compact expression of the Green's function and a discussion of the asymptotic behavior of the density matrix for insulating molecular chains.Comment: 13 pages, 11 figure

    The application of a numerical integration procedure developed by erwin fehlberg to the restricted problem of three bodies

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    Application of numerical integration procedures to restricted three-body proble

    The stratcom 8 effort

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    The ozone-nitrogen oxides ultraviolent flux interactions were investigated to obtain data on stratospheric photochemistry. The balloon, rocket, and aircraft operations are described along with the instruments, parameter measurements, and payloads

    Propagators weakly associated to a family of Hamiltonians and the adiabatic theorem for the Landau Hamiltonian with a time-dependent Aharonov-Bohm flux

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    We study the dynamics of a quantum particle moving in a plane under the influence of a constant magnetic field and driven by a slowly time-dependent singular flux tube through a puncture. The known adiabatic results do not cover these models as the Hamiltonian has time dependent domain. We give a meaning to the propagator and prove an adiabatic theorem. To this end we introduce and develop the new notion of a propagator weakly associated to a time-dependent Hamiltonian.Comment: Title and Abstract changed, will appear in Journal of Mathematical Physic

    A VLSI design for a systolic Viterbi decoder

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    A systolic Viterbi decoder for convolutional codes is developed. This decoder uses the trace-back method to reduce the amount of data needed to be stored in registers. It is shown that this new algorithm requires a smaller chip size and achieves a faster decoding time than other existing methods

    Resonances Width in Crossed Electric and Magnetic Fields

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    We study the spectral properties of a charged particle confined to a two-dimensional plane and submitted to homogeneous magnetic and electric fields and an impurity potential. We use the method of complex translations to prove that the life-times of resonances induced by the presence of electric field are at least Gaussian long as the electric field tends to zero.Comment: 3 figure
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