363 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

    Comparison of Relativistic Nucleon-Nucleon Interactions

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    We investigate the difference between those relativistic models based on interpreting a realistic nucleon-nucleon interaction as a perturbation of the square of a relativistic mass operator and those models that use the method of Kamada and Gl\"ockle to construct an equivalent interaction to add to the relativistic mass operator. Although both models reproduce the phase shifts and binding energy of the corresponding non-relativistic model, they are not scattering equivalent. The example of elastic electron-deuteron scattering in the one-photon-exchange approximation is used to study the sensitivity of three-body observables to these choices. Our conclusion is that the differences in the predictions of the two models can be understood in terms of the different ways in which the relativistic and non-relativistic SS-matrices are related. We argue that the mass squared method is consistent with conventional procedures used to fit the Lorentz-invariant cross section as a function of the laboratory energy.Comment: Revtex 13 pages, 5 figures, corrected some typo

    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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