1,750 research outputs found

    Radiation measurements from polar and geosynchronous satellites Semiannual report, 1 Oct. 1970 - 31 Mar. 1971

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    Radiation measurements from polar and synchronous satellites applied to problems of atmospheric circulation and energetic

    Meteorological measurements, Satellite PL Quarterly report, 1 Jun. - 31 Aug. 1968

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    Development of balloon-borne miniature radio altimeter and investigation of multiple array infrared imaging from synchronous satellite

    A computationally efficacious free-energy functional for studies of inhomogeneous liquid water

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    We present an accurate equation of state for water based on a simple microscopic Hamiltonian, with only four parameters that are well-constrained by bulk experimental data. With one additional parameter for the range of interaction, this model yields a computationally efficient free-energy functional for inhomogeneous water which captures short-ranged correlations, cavitation energies and, with suitable long-range corrections, the non-linear dielectric response of water, making it an excellent candidate for studies of mesoscale water and for use in ab initio solvation methods.Comment: 6 pages, 5 figure

    Meteorological application of Apollo photography Final report

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    Development of meteorological information and parameters based on cloud photographs taken during Apollo 9 fligh

    Zonal average earth radiation budget measurements from satellites for climate studies

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    Data from 29 months of satellite radiation budget measurements, taken intermittently over the period 1964 through 1971, are composited into mean month, season and annual zonally averaged meridional profiles. Individual months, which comprise the 29 month set, were selected as representing the best available total flux data for compositing into large scale statistics for climate studies. A discussion of spatial resolution of the measurements along with an error analysis, including both the uncertainty and standard error of the mean, are presented

    Evaluation of radiography as a screening method for detection and characterisation of congenital vertebral malformations in dogs

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    Congenital vertebral malformations (CVM) are common in brachycephalic ‘screw-tailed’ dogs; they can be associated with neurological deficits and a genetic predisposition has been suggested. The purpose of this study was to evaluate radiography as a screening method for congenital thoracic vertebral malformations in brachycephalic ‘screw-tailed’ dogs by comparing it with CT. Forty-nine dogs that had both radiographic and CT evaluations of the thoracic vertebral column were included. Three observers retrospectively reviewed the images independently to detect CVMs. When identified, they were classified according to a previously published radiographic classification scheme. A CT consensus was then reached. All observers identified significantly more affected vertebrae when evaluating orthogonal radiographic views compared with lateral views alone; and more affected vertebrae with the CT consensus compared with orthogonal radiographic views. Given the high number of CVMs per dog, the number of dogs classified as being CVM free was not significantly different between CT and radiography. Significantly more midline closure defects were also identified with CT compared with radiography. Malformations classified as symmetrical or ventral hypoplasias on radiography were frequently classified as ventral and medial aplasias on CT images. Our results support that CT is better than radiography for the classification of CVMs and this will be important when further evidence of which are the most clinically relevant CVMs is identified. These findings are of particular importance for designing screening schemes of CVMs that could help selective breeding programmes based on phenotype and future studies

    Asymmetric Colliding Nuclear Matter Approach in Heavy Ion Collisions

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    The early stage of a heavy ion collision is governed by local non-equilibrium momentum distributions which have been approximated by colliding nuclear matter configurations, i.e. by two Lorentz elongated Fermi ellipsoids. This approach has been extended from the previous assumption of symmetric systems to asymmetric 2-Fermi sphere configurations, i.e. to different densities. This provides a smoother transition from the limiting situation of two interpenetrating currents to an equilibrated system. The model is applied to the dynamical situations of heavy ion collisions at intermediate energies within the framework of relativistic transport (RBUU) calculations. We find that the extended colliding nuclear matter approach is more appropriate to describe collective reaction dynamics in terms of flow observables, in particular, for the elliptic flow at low energies.Comment: 21 pages, 8 figures, accepted for publication in Nuclear Physics

    Covariant representations of the relativistic Brueckner T-matrix and the nuclear matter problem

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    We investigate nuclear matter properties in the relativistic Brueckner approach. The in-medium on-shell T-matrix is represented covariantly by five Lorentz invariant amplitudes from which we deduce directly the nucleon self-energy. We discuss the ambiguities of this approach and the failure of previously used covariant representations in reproducing the nucleon self-energies on the Hartree-Fock level. To enforce correct Hartree-Fock results we develop a subtraction scheme which treats the bare nucleon-nucleon potential exactly in accordance to the different types of meson exchanges. For the remaining ladder kernel, which contains the higher order correlations, we employ then two different covariant representations in order to study the uncertainty inherent in the approach. The nuclear matter bulk properties are only slightly sensitive on the explicit representation used for the kernel. However, we obtain new Coester lines for the various Bonn potentials which are shifted towards the empirical region of saturation. In addition the nuclear equation-of-state turns out to be significantly softer in the new approach.Comment: 39 pages Latex using Elsevier style, 16 PS figure

    Exact closed-form solutions of the Dirac equation with a scalar exponential potential

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    The problem of a fermion subject to a general scalar potential in a two-dimensional world for nonzero eigenenergies is mapped into a Sturm-Liouville problem for the upper component of the Dirac spinor. In the specific circumstance of an exponential potential, we have an effective Morse potential which reveals itself as an essentially relativistic problem. Exact bound solutions are found in closed form for this problem. The behaviour of the upper and lower components of the Dirac spinor is discussed in detail, particularly the existence of zero modes.Comment: 16 pages, 3 figure

    Dielectronic Recombination in Li+ Ions

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    This research was sponsored by the National Science Foundation Grant NSF PHY-931478
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