13,013 research outputs found
Long spin coherence times in the ground state and an optically excited state of Er:YSiO at zero magnetic field
Spins in solids are an ideal candidate to act as a memory and interface with
superconducting qubits due to their long coherence times. We spectroscopically
investigate erbium-167-doped yttrium orthosilicate as a possible
microwave-addressed memory employing its microwave frequency transitions that
occur without applying an external magnetic field. We obtain coherence times of
380 s in a ground state spin transition and 1.48 ms in an excited state
spin transition. This is 28 times longer compared to previous zero field
measurements, as well as 200 times longer than a previous microwave memory
demonstration in the same material. These long coherence times show that
erbium-167-doped yttrium orthosilicate has potential as a microwave-addressed
quantum memory.Comment: 9 pages, 7 figures. The paper has been expanded compared to the
previous version on arXiv, and the title has change
The receptor-associated coactivator 3 activates transcription through CREB-binding protein recruitment and autoregulation
Transcriptional coactivators are involved in gene activation by nuclear hormone receptors. The receptor-associated coactivator 3 (RAC3) was recently identified to be highly related to the steroid receptor coactivator-1 and transcriptional intermediate factor 2, thereby establishing a novel family of nuclear receptor coactivators. In this study, we identified a RAC3 fragment containing three LXXLL motifs conserved among this family, which is sufficient to mediate nuclear receptor interaction in vivo and in vitro. Point mutations that disrupt ligand-dependent activation function of the receptor inhibited the interaction. We found that a 162-amino acid fragment of RAC3 conferred transcriptional activation and recruited the CREB-binding protein and that three distinct LXXLL motifs mediated the transcriptional activation. A trimeric far Western analysis demonstrated the formation of a ternary complex containing CREB-binding protein, RAC3, and the receptor. In addition, we showed that RAC3, transcriptional intermediate factor 2, and steroid receptor coactivator-1 are expressed in specific tissues and cancer cells and that RAC3 transcript is directly up-regulated by retinoid treatment. These results suggest that RAC3 may contribute to amplified transcriptional responses through both recruitment of additional coactivators and autoregulation by the receptor-coactivator complex
Line versus Flux Statistics -- Considerations for the Low Redshift Lyman-alpha Forest
The flux/transmission power spectrum has become a popular statistical tool in
studies of the high redshift () Lyman-alpha forest. At low redshifts,
where the forest has thinned out into a series of well-isolated absorption
lines, the motivation for flux statistics is less obvious. Here, we study the
relative merits of flux versus line correlations, and derive a simple condition
under which one is favored over the other on purely statistical grounds.
Systematic errors probably play an important role in this discussion, and they
are outlined as well.Comment: 6 pages, to appear in "The IGM/Galaxy Connection: The Distribution of
Baryons at z=0", eds. J. L. Rosenberg and M. E. Putma
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