2,501 research outputs found

    Open-closed field algebras

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    We introduce the notions of open-closed field algebra and open-closed field algebra over a vertex operator algebra V. In the case that V satisfies certain finiteness and reductivity conditions, we show that an open-closed field algebra over V canonically gives an algebra over a \C-extension of the Swiss-cheese partial operad. We also give a tensor categorical formulation and categorical constructions of open-closed field algebras over V.Comment: 55 pages, largely revised, an old subsection is deleted, a few references are adde

    Degravitation, Inflation and the Cosmological Constant as an Afterglow

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    In this report, we adopt the phenomenological approach of taking the degravitation paradigm seriously as a consistent modification of gravity in the IR, and investigate its consequences for various cosmological situations. We motivate degravitation-- where Netwon's constant is promoted to a scale dependent filter function-- as arising from either a small (resonant) mass for the graviton, or as an effect in semi-classical gravity. After addressing how the Bianchi identities are to be satisfied in such a set up, we turn our attention towards the cosmological consequences of degravitation. By considering the example filter function corresponding to a resonantly massive graviton (with a filter scale larger than the present horizon scale), we show that slow roll inflation, hybrid inflation and old inflation remain quantitatively unchanged. We also find that the degravitation mechanism inherits a memory of past energy densities in the present epoch in such a way that is likely significant for present cosmological evolution. For example, if the universe underwent inflation in the past due to it having tunneled out of some false vacuum, we find that degravitation implies a remnant `afterglow' cosmological constant, whose scale immediately afterwards is parametrically suppressed by the filter scale (LL) in Planck units Λlpl2/L2\Lambda \sim l^2_{pl}/L^2. We discuss circumstances through which this scenario reasonably yields the presently observed value for ΛO(10120)\Lambda \sim O(10^{-120}). We also find that in a universe still currently trapped in some false vacuum state, resonance graviton models of degravitation only degravitate initially Planck or GUT scale energy densities down to the presently observed value over timescales comparable to the filter scale.Comment: To appear in JCAP; sections discussing degravitation as a semi-classical effect and the modified Bianchi identities adde

    Evolution of asexual and sexual reproduction in the aspergilli

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    Aspergillus nidulans has long-been used as a model organism to gain insights into the genetic basis of asexual and sexual developmental processes both in other members of the genus Aspergillus, and filamentous fungi in general. Paradigms have been established concerning the regulatory mechanisms of conidial development. However, recent studies have shown considerable genome divergence in the fungal kingdom, questioning the general applicability of findings from Aspergillus, and certain longstanding evolutionary theories have been questioned. The phylogenetic distribution of key regulatory elements of asexual reproduction in A. nidulans was investigated in a broad taxonomic range of fungi. This revealed that some proteins were well conserved in the Pezizomycotina (e.g. AbaA, FlbA, FluG, NsdD, MedA, and some velvet proteins), suggesting similar developmental roles. However, other elements (e.g. BrlA) had a more restricted distribution solely in the Eurotiomycetes, and it appears that the genetic control of sporulation seems to be more complex in the aspergilli than in some other taxonomic groups of the Pezizomycotina. The evolution of the velvet protein family is discussed based on the history of expansion and contraction events in the early divergent fungi. Heterologous expression of the A. nidulans abaA gene in Monascus ruber failed to induce development of complete conidiophores as seen in the aspergilli, but did result in increased conidial production. The absence of many components of the asexual developmental pathway from members of the Saccharomycotina supports the hypothesis that differences in the complexity of their spore formation is due in part to the increased diversity of the sporulation machinery evident in the Pezizomycotina. Investigations were also made into the evolution of sex and sexuality in the aspergilli. MAT loci were identified from the heterothallic Aspergillus (Emericella) heterothallicus and Aspergillus (Neosartorya) fennelliae and the homothallic Aspergillus pseudoglaucus (=Eurotium repens). A consistent architecture of the MAT locus was seen in these and other heterothallic aspergilli whereas much variation was seen in the arrangement of MAT loci in homothallic aspergilli. This suggested that it is most likely that the common ancestor of the aspergilli exhibited a heterothallic breeding system. Finally, the supposed prevalence of asexuality in the aspergilli was examined. Investigations were made using A. clavatus as a representative ‘asexual’ species. It was possible to induce a sexual cycle in A. clavatus given the correct MAT1-1 and MAT1-2 partners and environmental conditions, with recombination confirmed utilising molecular markers. This indicated that sexual reproduction might be possible in many supposedly asexual aspergilli and beyond, providing general insights into the nature of asexuality in fungi.National Natural Science Foundation of China 31601446National Research Foundation of Korea 2016010945Intelligent Synthetic Biology Center of Global Frontier Projects 2015M3A6A8065838Biotechnology and Biological Sciences Research CouncilGovernment of IraqMinisterio de Economía y Competitividad BIO2015-67148-

    Interchannel coupling effects in the spin polarization of energetic photoelectrons

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    Effects of the interchannel coupling on the spin polarization of energetic photoelectrons emitted from atomic Ne valence subshells are examined. Like previously obtained results for cross sections and angular distributions, the photoelectron spin polarization parameters too are found considerably influenced by the coupling. The result completes a series of studies to finally conclude that the independent particle description is inadequate for the {\em entire} range of photoionization dynamics over the {\em full} spectral energy domainComment: 7 pages, 5 figures, accepted in Phys. Rev.

    Cultural Perspective on Parenting, Trait Emotional Intelligence and Mental Health in Taiwanese Children

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    The current study aims to clarify the associations as well as the pathways through which parenting and children's emotional intelligence (EI) may influence children's mental health with a cross-sectional sample of 675 school pupils (fourth grade, mean age = 10.4 years, 310 boy, 356 girls and 9 unidentified) in Taiwan. Hierarchical regression and path analyses were used to examine the relationships between parenting styles, children's trait EI, and their psychological symptoms, with children's psychological symptoms as the dependent variable. The results showed that authoritative parenting was positively associated with children‟s trait EI, which in turn had a negative effect on children‟s psychological symptoms, whereas authoritarian and Chinese-specific parenting styles had direct negative effect on children‟s psychological symptoms. These findings shed light on the pathways of the interrelations between different parenting styles, children's trait EI, and psychological symptoms, providing theoretical as well as practical implications for children's emotional development and mental health

    Highly Facet-reflection Immune 53GBaud EML for 800G Artificial Intelligence Optical Transceivers

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    We developed a facet-reflection immune 53GBaud electro-absorption modulated laser (EML) for 800G artificial intelligence (AI) optical network. An ultra-low anti-reflection (AR) coating reflectivity of 2x10-5 has been demonstrated for straight waveguide. Based on Hakki-Paoli method, we characterized the ultra-low AR using the ripple test technique. Such ultra-low AR is critical in achieving excellent eye pattern and optical transmission for 800G AI supercomputing

    A microsatellite marker for yellow rust resistance in wheat

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    Bulk segregant analysis (BSA) was used to identify molecular markers associated with yellow rust disease resistance in wheat (Triticum aestivum L.). DNAs isolated from the selected yellow rust tolerant and susceptible F-2 individuals derived from a cross between yellow rust resistant and susceptible wheat genotypes were used to established a "tolerant" and a "susceptible" DNA pool. The BSA was then performed on these DNA pools using 230 markers that were previously mapped onto the individual wheat chromosomes. One of the SSR markers (Xgwm382) located on chromosome group 2 (A, B, D genomes) was present in the resistant parent and the resistant bulk but not in the susceptible parent and the susceptible bulk, suggesting that this marker is linked to a yellow rust resistance gene. The presence of Xgwm382 was also tested in 108 additional wheat genotypes differing in yellow rust resistance. This analysis showed that 81% of the wheat genotypes known to be yellow rust resistant had the Xgwm382 marker, further suggesting that the presence of this marker correlates with yellow rust resistance in diverse wheat germplasm. Therefore, Xgwm382 could be useful for marker assisted selection of yellow rust resistances genotypes in wheat breeding programs

    Muon anomalous magnetic moment and the stabilized Randall-Sundrum scenario

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    We study the effects of extra dimension on the muon anomalous magnetic moment in the stabilized Randall-Sundrum scenario. The effects of the Kaluza-Klein states heavier than the cut-off scale expected to be of order Λπ\Lambda_\pi are neglected. Contribution from the spin-2 Kaluza-Klein states dominates over that from the spin-0 radion. The recent BNL E821 results impose a strict constraint on the parameter space of the model: Λπ0.42.1\Lambda_\pi \approx 0.4 - 2.1 TeV with k/MPl=0.010.1k/ M_{\rm Pl} =0.01 - 0.1. Small k/MPlk/M_{\rm Pl} is preferred if Λπ\Lambda_\pi is TeV scale.Comment: 9 pages, ReVTeX, reference added, version to appear in PL

    Nanoscale III-V Semiconductor Photodetectors for High-Speed Optical Communications

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    Nanophotonics involves the study of the behavior of light on nanometer scale. Modern nanoscale semiconductor photodetectors are important building blocks for high-speed optical communications. In this chapter, we review the state-of-the-art 2.5G, 10G, and 25G avalanche photodiodes (APDs) that are available in commercial applications. We discuss the key device parameters, including avalanche breakdown voltage, dark current, temperature dependence, bandwidth, and sensitivity. We also present reliability analysis on wear-out degradation and optical/electrical overload stress. We discuss the reliability challenges of nanoscale photodetectors associated with device miniaturization for the future. The reliability aspects in terms of high electric field, Joule heating, and geometry inhomogeneity are highlighted

    Leading Isgur-Wise form factor of ΛbΛc1\Lambda_b\to\Lambda_{c1} transition using QCD sum rules

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    The leading Isgur-Wise form factor ξ(y)\xi(y) parametrizing the semileptonic transitions ΛbΛc11/2νˉ\Lambda_b\to\Lambda^{1/2}_{c1}\ell\bar\nu and ΛbΛc13/2νˉ\Lambda_b\to\Lambda^{3/2}_{c1}\ell\bar\nu is calculated by using the QCD sum rules in the framework of heavy quark effective theory, where Λc11/2\Lambda^{1/2}_{c1} and Λc13/2\Lambda^{3/2}_{c1} is the orbitally excited charmed baryon doublet with JP=(1/2,3/2)J^P=(1^-/2,3^-/2). The interpolating currents with transverse covariant derivative are adopted for Λc11/2\Lambda^{1/2}_{c1} and Λc13/2\Lambda^{3/2}_{c1} in the analysis. The slope parameter ρ2\rho^2 in linear approximation of the Isgur-Wise function is obtained to be ρ2=2.01\rho^2=2.01, and the interception to be ξ(1)=0.29\xi(1)=0.29. The decay branching ratios are estimated.Comment: 16 pages, 3 figures, to appear in PL
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