35 research outputs found
pi+ + d --> p + p reaction between 18 and 44 MeV
A study of the reaction pi+ + d --> p + p has been performed in the energy
range of 18 - 44 MeV. Total cross sections and differential cross sections at
six angles have been measured at 15 energies with an energy increment of 1 - 2
MeV. This is the most systematic data set in this energy range. No structure in
the energy dependence of the cross section has been observed within the
accuracy of this experiment.Comment: 20 pages, 7 Postscript figure
Mesonic cloud contribution to the nucleon and delta masses
Pion-nucleon elastic scattering in the dominant channel is examined
in the model in which the interaction is of the form . New expressions are found for the elastic pion-nucleon
scattering amplitude which differ from existing formula both in the kinematics
and in the treatment of the renormalization of the nucleon mass and coupling
constant. Fitting the model to the phase shifts in the channel does
not uniquely fix the parameters of the model. The cutoff for the pion-nucleon
form factor is found to lie in the range MeV/c. The masses
of the nucleon and the which would arise if there were no coupling to
mesons are found to be MeV and MeV. The difference in these bare masses, a quantity which would
be accounted for by a residual gluon interaction, is found to be MeV.Comment: 26 pages, 9 figures, significant rewrit
Utilization of Fc receptors as a mucosal vaccine strategy against an intracellular bacterium, Francisella tularensis
Numerous studies have demonstrated that targeting Ag to Fc receptors (FcR) on APCs can enhance humoral and cellular immunity. However, studies are lacking that examine both the use of FcR-targeting in generating immune protection against infectious agents and the use of FcRs in the induction of mucosal immunity. Francisella tularensis is a category A intracellular mucosal pathogen. Thus, intense efforts are underway to develop a vaccine against this organism. We hypothesized that protection against mucosal infection with F. tularensis would be significantly enhanced by targeting inactivated F. tularensis live vaccine strain (iFt) to FcRs at mucosal sites, via intranasal immunization with mAb-iFt complexes. These studies demonstrate for the first time that: 1) FcR-targeted immunogen enhances immunogen-specific IgA production and protection against subsequent infection in an IgA-dependent manner, 2) FcgammaR and neonatal FcR are crucial to this protection, and 3) inactivated F. tularensis, when targeted to FcRs, enhances protection against the highly virulent SchuS4 strain of F. tularensis, a category A biothreat agent. In summary, these studies show for the first time the use of FcRs as a highly effective vaccination strategy against a highly virulent mucosal intracellular pathogen