995 research outputs found

    S matrix of collective field theory

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    By applying the Lehmann-Symanzik-Zimmermann (LSZ) reduction formalism, we study the S matrix of collective field theory in which fermi energy is larger than the height of potential. We consider the spatially symmetric and antisymmetric boundary conditions. The difference is that S matrices are proportional to momenta of external particles in antisymmetric boundary condition, while they are proportional to energies in symmetric boundary condition. To the order of gst2g_{st}^2, we find simple formulas for the S matrix of general potential. As an application, we calculate the S matrix of a case which has been conjectured to describe a "naked singularity".Comment: 19 page, LaTe

    Axial-flexural coupled vibration and buckling of composite beams using sinusoidal shear deformation theory

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    A finite element model based on sinusoidal shear deformation theory is developed to study vibration and buckling analysis of composite beams with arbitrary lay-ups. This theory satisfies the zero traction boundary conditions on the top and bottom surfaces of beam without using shear correction factors. Besides, it has strong similarity with Euler–Bernoulli beam theory in some aspects such as governing equations, boundary conditions, and stress resultant expressions. By using Hamilton’s principle, governing equations of motion are derived. A displacement-based one-dimensional finite element model is developed to solve the problem. Numerical results for cross-ply and angle-ply composite beams are obtained as special cases and are compared with other solutions available in the literature. A variety of parametric studies are conducted to demonstrate the effect of fiber orientation and modulus ratio on the natural frequencies, critical buckling loads, and load-frequency curves as well as corresponding mode shapes of composite beams

    3He/4He ratios of fumaroles and bubbling gases of hot springs in Tatun Volcano Group, North Taiwan

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    Eleven representative fumarolic gases and bubbling gases of hot springs have been collected from Tatun Volcano Group, North Taiwan for the helium isotope measurement. All the samples, except one, exhibit consistent corrected helium isotope ratios (3He/4He) with the mean value of 4.67 times of air ratios (RA). The preliminary helium data show that more than 60% of helium composition comes from deep magmatic source in this area. It implies that a relic magma reservoir may still exist underneath North Taiwan

    d_{x^2-y^2} Symmetry and the Pairing Mechanism

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    An important question is if the gap in the high temperature cuprates has d_{x^2-y^2} symmetry, what does that tell us about the underlying interaction responsible for pairing. Here we explore this by determining how three different types of electron-phonon interactions affect the d_{x^2-y^2} pairing found within an RPA treatment of the 2D Hubbard model. These results imply that interactions which become more positive as the momentum transfer increases favor d_{x^2-y^2} pairing in a nearly half-filled band.Comment: 9 pages and 2 eps figs, uses revtex with epsf, in press, PR

    Quasi-Periodic Releases of Streamer Blobs and Velocity Variability of the Slow Solar Wind near the Sun

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    We search for persistent and quasi-periodic release events of streamer blobs during 2007 with the Large Angle Spectrometric Coronagraph on the \textit{Solar and Heliospheric Observatory} and assess the velocity of the slow solar wind along the plasma sheet above the corresponding streamer by measuring the dynamic parameters of blobs. We find 10 quasi-periodic release events of streamer blobs lasting for three to four days. In each day of these events, we observe three-five blobs. The results are in line with previous studies using data observed near the last solar minimum. Using the measured blob velocity as a proxy for that of the mean flow, we suggest that the velocity of the background slow solar wind near the Sun can vary significantly within a few hours. This provides an observational manifestation of the large velocity variability of the slow solar wind near the Sun.Comment: 14 pages, 5 figures, accepted by Soalr Physic

    Don't touch: Developmental trajectories of toddlers' behavioral regulation related to older siblings' behaviors and parental discipline

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    Behavioral regulation is one of the key developmental skills children acquire during early childhood. Previous research has focused primarily on the role of parents as socializing agents in this process, yet it is likely that older siblings also are influential given the numerous daily interactions between siblings. This exploratory longitudinal study investigated developmental heterogeneity in behavioral regulation during toddlerhood and the early preschool years (18 to 36 months) and relations with older siblings' control and behavioral regulation while taking into account parental discipline. Toddlers were visited at home at 18, 24, and 36 months and observed during a gift-delay task with their older sibling in 93 families. Behavioral regulation of both siblings and gentle and harsh control of the older sibling were coded during the sibling gift-delay task, which was validated using parent-reports of toddlers' internalized conduct. Analyses revealed five distinct developmental trajectories among toddlers' behavioral regulation, revealing different patterns of developmental multifinality and equifinality. Older siblings' harsh control and parental discipline differed across toddler trajectory groups. Older siblings' behaviors covaried with the toddlers' behavioral regulation suggesting that older siblings may be acting as models for younger siblings, as well as disciplining and teaching toddlers to resist temptation.Education and Child Studie

    Azonexus hydrophilus sp nov., a nifH gene-harbouring bacterium isolated from freshwater

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    Three Gram-negative, non-pigmented, rod-shaped, facultatively aerobic bacterial strains, designated d8-1(T), d8-2 and IMCC1716, were isolated from a freshwater spring sample and a eutrophic freshwater pond. Based on characterization using a polyphasic approach, the three strains showed highly similar phenotypic, physiological and genetic characteristics. All of the strains harboured the nitrogenase gene nifH, but nitrogen-fixing activities could not be detected in nitrogen-free culture media. The three strains shared 99.6-99.7 % 16S rRNA gene sequence similarity and showed 89-100 % DNA-DNA relatedness, suggesting that they represent a single genomic species. Phylogenetic analysis based on 16S rRNA gene sequences showed that strains d8-1(T), d8-2 and IMCC1716 formed a monophyletic branch in the periphery of the evolutionary radiation occupied by the genus Azonexus. Their closest neighbours; were Azonexus caeni Slu-05(T) (96.7-96.8% similarity) and Azonexus fungiphilus BS5-8(T) (96.3-96.6 %). The DNA-DNA relatedness of the novel strains to these two species of the genus Azonexus was less than 70%. The isolates could also be differentiated from recognized members of the genus Azonexus on the basis of phenotypic and biochemical characteristics. It is evident, therefore, that the three strains represent a novel species of the genus Azonexus, for which the name Azonexus hydrophilus sp. nov. is proposed. The type strain is d8-1(T) (=LMG 24005(T)=BCRC 17657 (T))
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