526 research outputs found

    Scaling law for the electromagnetic form factors of the proton

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    The violation of the scaling law for the electric and magnetic form factors of the proton are examined within the cloudy bag model. The suppression of the ratio of the electric and magnetic form factors is natural in the bag model. The pion cloud plays a moderate role in understanding the recent data from TJNAF.Comment: 8 pages, REVTeX, 2 figures include

    High-Q2Q^2 Elastic eded-scattering and QCD predictions

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    In the framework of pertubative QCD it is argued that in the elastic eded-scattering at Q2Q^{2}\sim few (GeV/c)2(GeV/c)^{2} the light-cone-frame helicity-flip amplitudes could not be omitted. The obtained BA\frac{B}{A} ratio of Rosenbluth structure functions is shown to be in a good agreement with experimental data. The high Q2Q^2 behavior of tensor analysing power T20T_{20} is discussed.Comment: 6 pages + 2 ps figures not included, LaTeX, ITP-93-33

    Pilot study of DNA extraction from archival unstained bone marrow slides: comparison of three rapid methods

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    DNA can be isolated from a variety of human sample sources including anti-coagulant whole blood, bloodstains, hairs, tissue samples and buccal epithelial cells. The purpose of this study was to compare yield and quality of DNA samples obtained with the use of three different methods. The ability of these procedures to provide DNA for polymerase chain reaction (PCR) amplification from archival unstained bone marrow slides was tested on 35 different patients’ slides. Boiling in distilled water (A), proteinase K/Tween 35 method coupled with simplified phenol/chloroform isoamyl alcohol protocol (B) and modified commercial nucleon extraction and purification protocol (C, Amersham Life Science) gave extraction efficiencies of 57, 74 and 100% respectively. Our results demonstrate that rough DNA extraction methods have decreased efficiencies compared to complete DNA extraction protocols and that the latter are required to ensure highly reproducible results from archival unstained bone marrow slides.Key words: DNA, polymerase chain reaction, bone marrow slides, reagent ki

    Soft pion theorem for hard near threshold pion production

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    We prove new soft pion theorem for the near threshold pion production by a hard electromagnetic probe. This theorem relates various near threshold pion production amplitudes to the nucleon distribution amplitudes. The new soft pion theorem is in a good agreement with the SLAC data for F_2^p(W,Q^2) for W^2 < 1.4 GeV^2 and 7 < Q^2 < 30.7 GeV^2.Comment: 9 pages, revised version, more general analysi

    Does The 3N-Force Have A Hard Core?

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    The meson-nucleon dynamics that generates the hard core of the RuhrPot two-nucleon interaction is shown to vanish in the irreducible 3N force. This result indicates a small 3N force dominated by conventional light meson-exchange dynamics and holds for an arbitrary meson-theoretic Lagrangian. The resulting RuhrPot 3N force is defined in the appendix. A completely different result is expected when the Tamm-Dancoff/Bloch-Horowitz procedure is used to define the NN and 3N potentials. In that approach, (e.g. full Bonn potential) both the NN {\it and} 3N potentials contain non-vanishing contributions from the coherent sum of meson-recoil dynamics and the possibility of a large hard core requiring explicit calculation cannot be ruled out.Comment: 16 pages REVTeX + 3 ps fig
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