ACTIVE SUPPRESSION OF IMMUNOGLOBULIN ALLOTYPE SYNTHESIS : II. TRANSFER OF SUPPRESSING FACTOR WITH SPLEEN CELLS

The mechanism of chronic allotype suppression in (SJL x BALB/c)F1 mice has been investigated by means of cell transfer studies. These mice are phenotypically negative for serum Ig-1b, the paternal allotype determinant on γG2a immunoglubulin, as a result of perinatal exposure to maternal anti-Ig-1b. When spleen or bone marrow (B) cells from suppressed mice were injected into irradiated BALB/c "indicator" hosts, detectable levels of Ig-1b were demonstrated in the sera of a majority of the recipients early after transfer. These results indicate that Ig-1b-producing cells or their precursors are present in the lymphoid tissues of suppressed mice, even though they are not expressed. Within 5–7 wk, it was no longer possible to detect Ig-1b in the sera of these hosts, although cells producing another paternal allotype (Ig-4b) were shown to persist. Control BALB/c mice, injected with spleen and B cells from normal mice, continued to produce high levels of immunoglobulin carrying this allotype. The disappearance of serum, Ig-1b occurred most frequently in the recipients of suppressed spleen cells. Similar results were obtained using a mixture of spleen cells from normal and suppressed mice. Ig-1b production in the recipient mice ceased within a few weeks, even though the majority of cells in the mixture were obtained from normal (nonsuppressed) donors. The data are interpreted as evidence that chronic allotype suppression in mice is actively maintained by cells which are resident in the lymphoid tissues, splenic cells being the most effective. These cells are capable of proliferating in a new host and exerting their suppressive influence on Ig-1b-producing cells and/or their precursors

Electrically Small Supergain Arrays

The theory, computer simulations, and experimental measurements are presented for electrically small two-element supergain arrays with near optimal endfire gains of 7 dB. We show how the difficulties of narrow tolerances, large mismatches, low radiation efficiencies, and reduced scattering of electrically small parasitic elements are overcome by using electrically small resonant antennas as the elements in both separately driven and singly driven (parasitic) two-element electrically small supergain endfire arrays. Although rapidly increasing narrow tolerances prevent the practical realization of the maximum theoretically possible endfire gain of electrically small arrays with many elements, the theory and preliminary numerical simulations indicate that near maximum supergains are also achievable in practice for electrically small arrays with three (and possibly more) resonant elements if the decreasing bandwidth with increasing number of elements can be tolerated.Comment: 10 pages, 11 figures, submitted to IEEE Transactions on Antennas and Propagation (December 2006

Antireflection coatings from analogy between electron scattering and spin precession

We use the analogy between scattering of a wave from a potential, and the precession of a spin-half particle in a magnetic field, to gain insight into the design of an antireflection coating for electrons in a semiconductor superlattice. It is shown that the classic recipes derived for optics are generally not applicable due to the different dispersion law for electrons. Using the stability conditions we show that a Poisson distribution of impedance steps is a better approximation than is a Gaussian distribution. Examples are given of filters with average transmissivity exceeding 95% over an allowed band

Low Temperature Properties of Anisotropic Superconductors with Kondo Impurities

We present a self-consistent theory of superconductors in the presence of Kondo impurities, using large-$N$ slave-boson methods to treat the impurity dynamics. The technique is tested on the s-wave case and shown to give good results compared to other methods for $T_K > T_c$. We calculate low temperature thermodynamic and transport properties for various superconducting states, including isotropic s-wave and representative anisotropic model states with line and point nodes on the Fermi surface.Comment: 21 pages, RevTeX 3.0, 12 figures available upon request, UF preprin

Linkage in mice of genes controlling an immunoglobulin kappa-chain marker and the surface alloantigen Ly-3 on T lymphocytes

Evidence obtained using recombinant inbred and congenic mouse strains has shown that the PC8 locus responsible for determining a marker on a single k chain in inbred mice is linked to the Ly - 2,3 locus on chromosome 6. The upper limit of the map distance between these loci is approximately three centimorgans. This finding is discussed in relation to other known light-chain variants that are associated with the Ly - 2,3 locus.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/46753/1/251_2005_Article_BF01563929.pd