26,854 research outputs found
Paired Accelerated Frames
The geometrical and quantum mechanical basis for Davies' and Unruh's
acceleration temperature is traced to a type of quantum mechanical
(``achronal'') spin. Its existence and definition are based on pairs of
causally disjoint accelerated frames. For bosons the expected spin vector of
monochromatic particles is given by the ``Planckian power'' and the ``r.m.s.
thermal fluctuation'' spectra. Under spacetime translation the spin direction
precesses around that ``Planckian'' vector. By exhibiting the conserved
achronal spin four-current, we extend the identification of achronal spin from
single quanta to multiparticle systems. Total achronal spin conservation is
also shown to hold, even in the presence of quadratic interactions.Comment: 22 pages, Plain Tex, one figure. Also published in Proc. of the 7th
Marcel Grossmann Meeting edited by R.T. Jantzen and G.M. Keiser (World
Scientific, Singapore, 1996), 957-976. Related papers on accelerated frames
are available at http://www.math.ohio-state.edu/~gerlac
Modification of H-2 Antigenic Sites by Enzymatic Treatment Influences Virus-Specific Target Cell Lysis
Vaccinia virus-infected cells were treated enzymatically to remove H-2 antigenic sites. The effect of this procedure on virus-specific cell-mediated cytolysis (CMC) and virus-specific antibody-mediated cytolysis (AMC) was tested. Due to the inhibition of cellular proteinsynthesis by the vaccinia virus infection, H-2 antigenic sites were not resynthesized while there was a continuous production of viral surface antigens.
These cells with a high concentration of viral surface antigens and decreased H-2 determinants could be used as targets in the virus specific AMC. But they were not lysed in the virus specific CMC which emphasizes the significance of H-2 antigens during recognition of virus-specific determinants by T cells
Radiation from Bodies with Extreme Acceleration II: Kinematics
When applied to a dipole source subjected to acceleration which is violent
and long lasting (``extreme acceleration''), Maxwell's equations predict
radiative power which augments Larmor's classical radiation formula by a
nontrivial amount. The physical assumptions behind this result are made
possible by the kinematics of a system of geometrical clocks whose tickings are
controlled by cavities which are expanding inertially. For the purpose of
measuring the radiation from such a source we take advantage of the physical
validity of a spacetime coordinate framework (``inertially expanding frame'')
based on such clocks. They are compatible and commensurable with the
accelerated clocks of the accelerated source. By contrast, a common Lorentz
frame with its mutually static clocks won't do: it lacks that commensurability.
Inertially expanding clocks give a physicist a window into the frame of a
source with extreme acceleration. He thus can locate that source and measure
radiation from it without being subjected to such acceleration himself. The
conclusion is that inertially expanding reference frames reveal qualitatively
distinct aspects of nature which would not be accessible if static inertial
frames were the only admissible frames.Comment: This 21-page 13-figure RevTeX4 article is a follow-up to Part I:
"Radiation from violently accelerated bodies", gr-qc/011004
Role of early viral surface antigens in cellular immune response to vaccinia virus
Infection of mice with the vaccinia virus strain WR, Elstree or DIs, a conditional lethal mutant of vaccinia virus, resulted in the generation of vaccinia virus-specific sensitized cytolytic T lymphocytes (CTL). It could be shown by cross-reactivity between the three strains and by inhibition experiments with specific antisera that early vaccinia surface antigens are sufficient for the generation of specific CTL in vivo and for the lysis of infected target cells in vitro
Silicon consumption and population density changes of dominant planktonic diatoms in Lake Constance
(1) Interactions between silicon concentration and diatom growth have been studied in Lake Constance with data on number and volume of cells per unit volume of water and concentration of dissolved reactive silicon. (2) Concentration of dissolved reactive silicon was found to decrease markedly during the spring and summer growth period of diatoms in 1979 and 1980. (3) Amounts of silicon taken up per cell and per unit cell volume have been calculated from the changes in silicon concentration and the increases in population density for several diatom species. The silicon to cell quotient (mg per million cells) varied over a wide range from 0.005 for Stephanodiscus hantzschii to 0.72 for Synedra acus, while that of silicon per unit cell volume (mg mm-3) varied over a narrower range from 0. 10 for Stephanodiscus hantzschii and Fragilaria crotonesis to 0.36 for Synedra acus. (4) A four-compartment model, that allows estimates of the rates of growth and of loss of diatom populations to be calculated, is outlined. (5) Summer succession from Asterionellaformosa to either Fragilaria crotonensis (in 1979) or Stephanodiscus binderanus (in 1980) is explained by interspecific differences in the effects of silicon concentration on growth and death. For Asterionellaformosa, silicon depletion did not stop cell-division but led to the death of most of the population. For Fragilaria crotonensis and Stephanodiscus binderanus cell division stopped but cells did not die and population growth continued after the concentration of dissolved silicon had increased agai
Cytotoxic interaction of virus specific effector cells with virus infected targets of different cell type
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