4,498 research outputs found
High Energy Quark-Antiquark Elastic scattering with Mesonic Exchange
We studies the high energy elastic scattering of quark anti-quark with an
exchange of a mesonic state in the channel with .
Both the normalization factor and the Regge trajectory can be calculated in
PQCD in cases of fixed (non-running) and running coupling constant. The
dependence of the Regge trajectory on the coupling constant is highly
non-linear and the trajectory is of order of in the interesting physical
range.Comment: 29 page
Issues of Reggeization in Back-Angle Scattering
The Kirschner-Lipatov result for the DLLA of high-energy backward
scattering is re-derived without the use of integral equations. It is shown
that part of the inequalities between the variables in the
logarithmically-divergent integrals is inconsequential. The light-cone
wave-function interpretation under the conditions of backward scattering is
discussed. It is argued that for hadron-hadron scattering in the valence-quark
model the reggeization should manifest itself at full strength starting from
.Comment: 10 Pages, 2 Figures. To appear in Proc. of Int. Conf. "New Trends in
High Energy Physics", 27 Sept.-4 Oct. 2008, Yalta, Crimea, Ukrain
Imaging of Magnetic Microstructures at Surfaces: The Scanning Electron Microscope with Spin Polarization Analysis
The scanning electron microscope with spin polarization analysis of secondary electrons has been proven to be a powerful tool for studying magnetic microstructures. Secondary electrons created at the surface of a ferromagnet are spin-polarized and contain information about the sample magnetization and its orientation. The combination of a spin polarization analyzer with a scanning electron microscope yields an unique apparatus for probing magnetic properties on a very small lateral scale. The magnetic resolution of \u3c 40 nm is demonstrated. This type of microscope provides high magnetic contrast, while the surface morphology is strongly or even totally suppressed. The capability of studying magnetic properties of semi- infinite samples as well as in ultrathin films is demonstrated with a Fe(lOO) single crystal, video tape, CoCr perpendicular recording medium and ultrathin cobalt films
Chemical reactivity of hydrogen, nitrogen and oxygen atoms at temperatures below 100 deg K Fifth semiannual technical report
Chemical reactivity of hydrogen, nitrogen, and oxygen atoms at temperatures below 100 deg
Membrane structure in isolated and intact myelins
The biochemical composition of myelin and the topology of its constituent lipids and proteins are typically studied using membranes that have been isolated from whole, intact tissue using procedures involving hypotonic shock and sucrose density gradient centrifugation. To what extent, however, are the structure and intermembrane interactions of isolated myelin similar to those of intact myelin? We have previously reported that intact and isolated myelins do not always show identical myelin periods, indicating a difference in membrane-membrane interactions. The present study addresses the possibility that this is due to altered membrane structure. Because x-ray scattering from isolated myelin sometimes consists of overlapping Bragg reflections or is continuous, we developed nonlinear least squares procedures for analyzing the total intensity distribution after film scaling, background subtraction, and Lorentz correction. We calculated electron density profiles of isolated myelin for comparison with membrane profiles from intact myelin. The change in the width of the extracellular space and the relative invariance of the cytoplasmic space as a function of pH and ionic strength that we previously found for intact nerve was largely paralleled by isolated myelin. There were two exceptions: isolated CNS myelin was resistant to swelling under all conditions, and isolated PNS myelin in hypotonic saline showed indefinite swelling at the extracellular apposition. However, electron density profiles of isolated myelins, calculated to 30 A resolution, did not show any major change in structure compared with intact myelin that could account for the differences in interactions
Dynamic approach for micromagnetics close to the Curie temperature
In conventional micromagnetism magnetic domain configurations are calculated
based on a continuum theory for the magnetization which is assumed to be of
constant length in time and space. Dynamics is usually described with the
Landau-Lifshitz-Gilbert (LLG) equation the stochastic variant of which includes
finite temperatures. Using simulation techniques with atomistic resolution we
show that this conventional micromagnetic approach fails for higher
temperatures since we find two effects which cannot be described in terms of
the LLG equation: i) an enhanced damping when approaching the Curie temperature
and, ii) a magnetization magnitude that is not constant in time. We show,
however, that both of these effects are naturally described by the
Landau-Lifshitz-Bloch equation which links the LLG equation with the theory of
critical phenomena and turns out to be a more realistic equation for
magnetization dynamics at elevated temperatures
Quantification of soil mapping by digital analysis of LANDSAT data
Soil survey mapping units are designed such that the dominant soil represents the major proportion of the unit. At times, soil mapping delineations do not adequately represent conditions as stated in the mapping unit descriptions. Digital analysis of LANDSAT multispectral scanner (MSS) data provides a means of accurately describing and quantifying soil mapping unit composition. Digital analysis of LANDSAT MSS data collected on 9 June 1973 was used to prepare a spectral soil map for a 430-hectare area in Clinton County, Indiana. Fifteen spectral classes were defined, representing 12 soil and 3 vegetation classes. The 12 soil classes were grouped into 4 moisture regimes based upon their spectral responses; the 3 vegetation classes were grouped into one all-inclusive class
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