84 research outputs found
Electromagnetic-field quantization and spontaneous decay in left-handed media
We present a quantization scheme for the electromagnetic field interacting
with atomic systems in the presence of dispersing and absorbing
magnetodielectric media, including left-handed material having negative real
part of the refractive index. The theory is applied to the spontaneous decay of
a two-level atom at the center of a spherical free-space cavity surrounded by
magnetodielectric matter of overlapping band-gap zones. Results for both big
and small cavities are presented, and the problem of local-field corrections
within the real-cavity model is addressed.Comment: 15 pages, 5 figures, RevTe
Lambda Hyperons in 2 A*GeV Ni + Cu Collisions
A sample of Lambda's produced in 2 A*GeV Ni + Cu collisions has been obtained
with the EOS Time Projection Chamber at the Bevalac. Low background in the
invariant mass distribution allows for the unambiguous demonstration of Lambda
directed flow. The transverse mass spectrum at mid-rapidity has the
characteristic shoulder-arm shape of particles undergoing radial transverse
expansion. A linear dependence of Lambda multiplicity on impact parameter is
observed, from which a total Lambda + Sigma^0 production cross section of $112
+/- 24 mb is deduced. Detailed comparisons with the ARC and RVUU models are
made.Comment: Revised version accepted for publication in Phys. Lett.
A PEG-ELISA for the detection of Leishmania donovani antigen in circulating immune complexes
Leishmanial antigen in circulating immune complexes (CIC) from sera of cotton-rats experimentally infected with Leishmania donovani and visceral leishmaniasis patients (VLP) was detected using a polyethylene glycol (PEG) enzyme-linked immunosorbent assay (peg-elisa). The immune complexes were precipitated in the cold with 12% PEG (average Mr 6000) and then dissociated with glycine-HCl buffer. The dissociated antigen bound to the plate was then detected by peroxidase-labelled rabbit antibody raised to either amastigotes or to CIC. Serum samples from either controls or patients infected with heterologous organisms were used to define the sensitivity and specificity of the test. Leishmanial antigen was detected in the CIC from all experimentally infected animals (100% sensitivity) and in 22 of 25 of the CIC from VLP (88% sensitivity), using either conjugate. Immunoblotting of PEG-precipitated CIC from infected animals with both rabbit antisera revealed multiple antigen components. Antigens of 40, 42 and 45 kDa appeared to be specifically recognized by both antibodies; the components of 40 and 42 kDa were common to amastigote extracts and CIC from infected animals
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