2,226 research outputs found
The immunological relationship between filtrable agent, Salmonella and murine leukosis
Salmonella typhimurium was invariably isolated from our J strain murine leukosis. Immunization of D103 mice with either inactivated Salmonella typhimurium or the cell-free extract of leukosis inhibited the transplantation of leukosis. The adoptive immunization of D103 mice with spleen cells of Strong A mice immunized with either Salmonella or the cell-free extract of leukosis inhibited the transplantation of leukosis. The addition of either Salmonella or the cell-free extract of leukosis inhibited the migration of macrophages of leukosis spleen in tissue culture. Strong A mice is non-susceptible to J strain leukosis. However, inoculation of neonatal Strong A mice with the cell-free extract of leukosis produced a susceptibility to the transplantation of leukosis. These results suggest that both a filtrable agent and Salmonella typhimurium are present in cells of this leukosis and might be etiologically related to the leukosis.</p
Evolution of cosmological perturbations in a stage dominated by an oscillatory scalar field
In the investigation of the evolution of cosmological perturbations in
inflationary universe models the behavior of perturbations during the reheating
stage is the most unclear point. In particular in the early reheating phase in
which a rapidly oscillating scalar field dominates the energy density, the
behavior of perturbations are not known well because their evolution equation
expressed in terms of the curvature perturbation becomes singular. In this
paper it is shown that in spite of this singular behavior of the evolution
equation the Bardeen parameter stays constant in a good accuracy during this
stage for superhorizon-scale perturbations except for a sequence of negligibly
short intervals around the zero points of the time derivative of the scalar
field. This justifies the conventional formula relating the amplitudes of
quantum fluctuations during inflation and those of adiabatic perturbations at
horizon crossing in the Friedmann stage, except for possible corrections
produced by the energy transfer from the scalar field to radiation in the late
stage of reheating. It is further shown that outside the above sequence of time
intervals the behavior of the perturbations coincides in a good accuracy with
that for a perfect fluid system obtained from the original scalar field system
by the WKB approximation and a spacetime averaging over a Hubble horizon scale.Comment: Revised version, 23 pages, no figure, plain LaTeX, minor errors in
some equations are corrected, no change in the main results and the
conclusio
Defining the Nambu--Jona-Lasinio Model by Higher Derivative Kinetic Term
Usual treatment of the Nambu--Jona-Lasinio (NJL) model using loop momentum
cutoff suffers from ambiguities in choosing the loop momenta to be cut off and
violation of (external) gauge invariance. We define the NJL model from the
starting Lagrangian level by using a higher derivative fermion kinetic term
with a cutoff parameter . This definition is free from such
ambiguities and manifestly keeps the chiral symmetry as well as the gauge
invariance. Quantization of this higher derivative system, current operators
and calculational method are discussed in some detail. Calculating the pion
decay constant and decay amplitude, we explicitly
demonstrate that the low energy theorem holds. It is observed that the NJL mass
relation between the meson and fermion masses no
longer holds in this model. We also present a simplified calculational method
which is valid when the cutoff parameter is much larger than the
energy scale of physics.Comment: 31 pages, phyzzx, 3 uuencoded epsf figures, KUNS-126
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