639 research outputs found

    On the origin of the hump structure in the in-plane optical conductivity of high Tc cuprates based on a SU(2) slave-boson theory

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    An improved version of SU(2) slave-boson approach is applied to study the in-plane optical conductivity of the two dimensional systems of high Tc cuprates. We investigate the role of fluctuations of both the phase and amplitude of order parameters on the (Drude) peak-dip-hump structure in the in-plane conductivity as a function of hole doping concentration and temperature. The mid-infrared(MIR) hump in the in-plane optical conductivity is shown to originate from the antiferromagnetic spin fluctuations of short range(the amplitude fluctuations of spin singlet pairing order parameters), which is consistent with our previous U(1) study. However the inclusion of both the phase and amplitude fluctuations is shown to substantially improve the qualitative feature of the optical conductivity by showing substantially reduced Drude peak widths for entire doping range. Both the shift of the hump position to lower frequency and the growth of the hump peak height with increasing hole concentration is shown to be consistent with observations.Comment: 7 pages, 6 figure

    Supernova Axion Emissivity with Δ(1232)\Delta(1232) Resonance in Heavy Baryon Chiral Perturbation Theory

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    In this paper, we evaluate the energy loss rate of supernovae induced by the axion emission process π+pn+a\pi^- + p \to n + a with the Δ(1232)\Delta(1232) resonance in the heavy baryon chiral perturbation theory for the first time. Given the axion-nucleon-Δ\Delta interactions, we include the previously ignored Δ\Delta-mediated graphs to the π+pn+a\pi^- + p \to n + a process. In particular, the Δ0\Delta^0-mediated diagram can give a resonance contribution to the supernova axion emission rate when the center-of-mass energy of the pion and proton approaches the Δ(1232)\Delta(1232) mass. With these new contributions, we find that for the typical supernova temperatures, compared with the earlier work with the axion-nucleon (and axion-pion-nucleon contact) interactions, the supernova axion emissivity can be enhanced by a factor of \sim4(2) in the Kim-Shifman-Vainshtein-Zakharov model and up to a factor of \sim5(2) in the Dine-Fischler-Srednicki-Zhitnitsky model with small tanβ\tan\beta values. Remarkably, we notice that the Δ(1232)\Delta(1232) resonance gives a destructive contribution to the supernova axion emission rate at high supernova temperatures, which is a nontrivial result in this study.Comment: 17 pages, 4 figures, typo is fixed, references updated. Matches version published in Physical Review

    The Interaction of Phospholipase C-{beta}3 with Shank2 Regulates mGluR-mediated Calcium Signal

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    Phospholipase C-{beta} isozymes that are activated by G protein-coupled receptors (GPCR) and heterotrimeric G proteins carry a PSD-95/Dlg/ZO-1 (PDZ) domain binding motif at their C terminus. Through interactions with PDZ domains, this motif may endow the PLC-{beta} isozyme with specific roles in GPCR signaling events that occur in compartmentalized regions of the plasma membrane. In this study, we identified the interaction of PLC-{beta}3 with Shank2, a PDZ domain-containing multimodular scaffold in the postsynaptic density (PSD). The C terminus of PLC-{beta}3, but not other PLC-{beta} isotypes, specifically interacts with the PDZ domain of Shank2. Homer 1b, a Shank-interacting protein that is linked to group I metabotropic glutamate receptors and IP3 receptors, forms a multiple complex with Shank2 and PLC-{beta}3. Importantly, microinjection of a synthetic peptide specifically mimicking the C terminus of PLC-{beta}3 markedly reduces the mGluR-mediated intracellular calcium response. These results demonstrate that Shank2 brings PLC-{beta}3 closer to Homer 1b and constitutes an efficient mGluR-coupled signaling pathway in the PSD region of neuronal synapses

    Precursor Phenomena of Barium Titanate Single Crystals Grown Using a Solid-State Single Crystal Growth Method Studied with Inelastic Brillouin Light Scattering and Birefringence Measurements

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    The nature of precursor phenomena in the paraelectric phase of ferroelectrics is one of the main questions to be resolved from a fundamental point of view. Barium titanate (BaTiO3) is one of the most representative perovskite-structured ferroelectrics intensively studied until now. The pretransitional behavior of BaTiO3 single crystal grown using a solid-state crystal growth (SSCG) method was investigated for the first time and compared to previous results. There is no melting process in the SSCG method, thus the crystal grown using a SSCG method have inherent higher levels of impurity and defect concentrations, which is a good candidate for investigating the effect of crystal quality on the precursor phenomena. The acoustic, dielectric, and piezoelectric properties, as well as birefringence, of the SSCG-grown BaTiO3 were examined over a wide temperature range. Especially, the acoustic phonon behavior was investigated in terms of Brillouin spectroscopy, which is a complementary technique to Raman spectroscopy. The obtained precursor anomalies of the SSCG-grown BaTiO3 in the cubic phase were similar to those of other single crystals, in particular, of high-quality single crystal grown by top-seeded solution growth method. These results clearly indicate that the observed precursor phenomena are common and intrinsic effect irrespective of the crystal quality

    Comparison of The Genome Profiles Between Head and Body Lice

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    The body louse (Pediculus humanus humanus) is known to have diverged from the head louse (P. humanus capitis) but genomic differences between these two subspecies still remain unexplored. To compare genomic profiles between head and body lice, whole genome sequences of head lice were determined by next generation sequencing methods based on both Illumina Genome analyzer and Roche GS FLX pyrosequencing and compared with the reference genome sequences of the body louse. Total consensuses generated by mapping to the body louse genome in conjunction with de novo assembly of head louse genome sequences revealed a head louse genome size of 110 Mbp with a 96% coverage of the body louse genome sequences. A total of 12,651 genes were predicted from the head louse genome sequences although more precise assembly and functional annotation of the genome is required for a more accurate gene count. Among the 873 genes that were putatively specific to the head louse, 15 genes were confirmed to be transcribed in both head and body lice, suggesting the previously estimated gene number of the body louse was likely underestimated. The single nucleotide polymorphism analysis showed that the nucleotide diversity of genome between head and body lice was 2.2%, which was larger than that of the transcriptome between head and body lice. An endosymbiont genome analysis showed that the composition of endosymbionts in head lice was similar to that of body lice and Candidatus Riesia pediculicola was the primary endosymbiont in both head and body lice
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