2,455 research outputs found
Shifting donor-acceptor photoluminescence in N-doped ZnO
We have grown nitrogen-doped ZnO films grown by two kinds of epitaxial
methods on lattice-matched ScAlMgO substrates. We measured the
photoluminescence (PL) of the two kinds of ZnO:N layers in the
donor-acceptor-pair transition region. The analysis of excitation-intensity
dependence of the PL peak shift with a fluctuation model has proven that our
observed growth-technique dependence was explained in terms of the
inhomogeneity of charged impurity distribution. It was found that the
inhomogeneity in the sample prepared with the process showing better electrical
property was significantly smaller in spite of the similar nitrogen
concentration. The activation energy of acceptor has been evaluated to be
meV, which is independent of the nitrogen concentration.Comment: 4 pages, 3 figures, 1 table, RevTeX4, to appear in the July issue of
J. Phys. Soc. Jp
Hamiltonian Formalism of the de-Sitter Invariant Special Relativity
Lagrangian of the Einstein's special relativity with universal parameter
() is invariant under Poincar\'e transformation which preserves
Lorentz metric . The has been extended to be
one which is invariant under de Sitter transformation that preserves so called
Beltrami metric . There are two universal parameters and in
this Special Relativity (denote it as ). The
Lagrangian-Hamiltonian formulism of is formulated in this
paper. The canonic energy, canonic momenta, and 10 Noether charges
corresponding to the space-time's de Sitter symmetry are derived. The canonical
quantization of the mechanics for -free particle is
performed. The physics related to it is discussed.Comment: 24 pages, no figur
The human t(1;19) translocation in pre-B ALL produces multiple nuclear E2A-Pbx1 fusion proteins with differing transforming potentials
The t(1;19) translocation that characterizes 25% of pediatric pre-B cell acute lymphoblastic leukemias (pre-B ALL) produces a chimeric gene, joining 5' sequences that encode a transcriptional activator domain of E2A with 3' sequences that, in part, encode a homeo box domain of a new gene called pbx1. Two E2A-pbx1 transcripts have been cloned. They encode the putative fusion proteins, p85^(E2A-Pbx1) and p77^(E2A-Pbx1), which differ in Pbx1 sequences alone, containing unique carboxyl termini whose sequences diverge after the Pbx1 homeo box. In this study, an antiserum to Pbx1 was used to investigate the identity and abundance of E2A-Pbx1 fusion proteins in both the pre-B ALL cell line, 697, and in cryopreserved leukemic bone marrow cells, obtained from six children with t(1;19)-positive pre-B ALL. Five species of E2A-Pbx1 proteins were identified in all cells containing t(1;19), two of which were indistinguishable from in vitro-translated p85^(E2A-Pbx1) and p77^(E2A-Pbx1). To assess the biological properties of p85^(E2A-Pbx1) and p77^(E2A-Pbx1) in fibroblasts, the cDNAs encoding these proteins were cloned into retroviral vectors, and each was introduced into NIH-3T3 cells. Both p85^(E2A-Pbx1) and p77^(E2A-Pbx1) are localized in the nucleus, and expression of either resulted in malignant conversion of NIH-3T3 cells as assayed by tumor formation in nude mice. When scored by focus formation, density-independent growth, and growth in agar assays, p77^(E2A-Pbx1) was a much more potent transforming protein than was p85^(E2A-Pbx1). Because subtle mutations in p85^(E2A-Pbx1) converted its transforming activity into that of p77^(E2A-Pbx1), we suggest that a sequence within the unique carboxyl terminus of p85^(E2A-Pbx1) serves to negatively regulate its biochemical activity
From the Complete Yang Model to Snyder's Model, de Sitter Special Relativity and Their Duality
By means of Dirac procedure, we re-examine Yang's quantized space-time model,
its relation to Snyder's model, the de Sitter special relativity and their
UV-IR duality. Starting from a dimensionless dS_5-space in a 5+1-d Mink-space a
complete Yang model at both classical and quantum level can be presented and
there really exist Snyder's model, the dS special relativity and the duality.Comment: 7 papge
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