5,036 research outputs found

    Does rationality matter to the central bank?

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    Rationality is one of the main assumptions in economics, and is represented as the rational expectation in macroeconomics. As such, it is important to note that the effectiveness of economic policy depends on the degree of economic agents’ rationality. According to this point of view, it is only natural to ask how the central bank views economic agents to be either rational or bounded rational. In implementing economic policies, it is possible to assume that the central bank views economic agents to be bounded rational. This is due to the fact that most theoretical arguments state that policy under rationality is not as effective as one under bounded rationality. Based on this argument, this paper employs bounded rational New Keynesian Model proposed by Gabaix to know if rationality matters to the central bank. As a result, as long as the central bank does not follow the full gradualism, it is possible to conclude that the rationality matters to the central bank. However, it is not anymore if the central bank employs full gradualism in monetary policy rule

    Superfluid-insulator transition of the Josephson junction array model with commensurate frustration

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    We have studied the rationally frustrated Josephson-junction array model in the square lattice through Monte Carlo simulations of (2+1)(2+1)D XY-model. For frustration f=1/4f=1/4, the model at zero temperature shows a continuous superfluid-insulator transition. From the measurement of the correlation function and the superfluid stiffness, we obtain the dynamical critical exponent z=1.0z=1.0 and the correlation length critical exponent ν=0.4±0.05\nu=0.4 \pm 0.05. While the dynamical critical exponent is the same as that for cases f=0f=0, 1/2, and 1/3, the correlation length critical exponent is surprisingly quite different. When f=1/5f=1/5, we have the nature of a first-order transition.Comment: RevTex 4, to appear in PR

    N_pN_n dependence of empirical formula for the lowest excitation energy of the 2^+ states in even-even nuclei

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    We examine the effects of the additional term of the type eλNpNn\sim e^{- \lambda' N_pN_n} on the recently proposed empirical formula for the lowest excitation energy of the 2+2^+ states in even-even nuclei. This study is motivated by the fact that this term carries the favorable dependence of the valence nucleon numbers dictated by the NpNnN_pN_n scheme. We show explicitly that there is not any improvement in reproducing Ex(21+)E_x(2_1^+) by including the extra NpNnN_pN_n term. However, our study also reveals that the excitation energies Ex(21+)E_x(2_1^+), when calculated by the NpNnN_pN_n term alone (with the mass number AA dependent term), are quite comparable to those calculated by the original empirical formula.Comment: 14 pages, 5 figure

    Effect of in-plane line defects on field-tuned superconductor-insulator transition behavior in homogeneous thin film

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    Field-tuned superconductor-insulator transition (FSIT) behavior in 2D isotropic and homogeneous thin films is usually accompanied by a nonvanishing critical resistance at low TT. It is shown that, in a 2D film including line defects paralle to each other but with random positions perpendicular to them, the (apparent) critical resistance in low TT limit vanishes, as in the 1D quantum superconducting (SC) transition, under a current parallel to the line defects. This 1D-like critical resistive behavior is more clearly seen in systems with weaker point disorder and may be useful in clarifying whether the true origin of FSIT behavior in the parent superconductor is the glass fluctuation or the quantum SC fluctuation. As a by-product of the present calculation, it is also pointed out that, in 2D films with line-like defects with a long but {\it finite} correlation length parallel to the lines, a quantum metallic behavior intervening the insulating and SC ones appears in the resistivity curves.Comment: 16 pages, 14 figure

    Phase Transitions in the Two-Dimensional XY Model with Random Phases: a Monte Carlo Study

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    We study the two-dimensional XY model with quenched random phases by Monte Carlo simulation and finite-size scaling analysis. We determine the phase diagram of the model and study its critical behavior as a function of disorder and temperature. If the strength of the randomness is less than a critical value, σc\sigma_{c}, the system has a Kosterlitz-Thouless (KT) phase transition from the paramagnetic phase to a state with quasi-long-range order. Our data suggest that the latter exists down to T=0 in contradiction with theories that predict the appearance of a low-temperature reentrant phase. At the critical disorder TKT0T_{KT}\rightarrow 0 and for σ>σc\sigma > \sigma_{c} there is no quasi-ordered phase. At zero temperature there is a phase transition between two different glassy states at σc\sigma_{c}. The functional dependence of the correlation length on σ\sigma suggests that this transition corresponds to the disorder-driven unbinding of vortex pairs.Comment: LaTex file and 18 figure

    A novel sulfonamide resistance mechanism by two-component flavin-dependent monooxygenase system in sulfonamide-degrading actinobacteria

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    Sulfonamide-degrading bacteria have been discovered in various environments, suggesting the presence of novel resistance mechanisms via drug inactivation. In this study, Microbacterium sp. CJ77 capable of utilizing various sulfonamides as a sole carbon source was isolated from a composting facility. Genome and proteome analyses revealed that a gene cluster containing a flavin-dependent monooxygenase and a flavin reductase was highly up-regulated in response to sulfonamides. Biochemical analysis showed that the two-component monooxygenase system was key enzymes for the initial cleavage of sulfonamides. Co-expression of the two-component system in Escherichia coli conferred decreased susceptibility to sulfamethoxazole, indicating that the genes encoding drug-inactivating enzymes are potential resistance determinants. Comparative genomic analysis revealed that the gene cluster containing sulfonamide monooxygenase (renamed as sulX) and flavin reductase (sulR) was highly conserved in a genomic island shared among sulfonamide-degrading actinobacteria, all of which also contained sul1-carrying class 1 integrons. These results suggest that the sulfonamide metabolism may have evolved in sulfonamide-resistant bacteria which had already acquired the class 1 integron under sulfonamide selection pressures. Furthermore, the presence of multiple insertion sequence elements and putative composite transposon structures containing the sulX gene cluster indicated potential mobilization. This is the first study to report that sulX responsible for both sulfonamide degradation and resistance is prevalent in sulfonamide-degrading actinobacteria and its genetic signatures indicate horizontal gene transfer of the novel resistance gene

    Two-Photon Absorption Of Di-Alkyl-Amino-Nitro-Stilbene Side-Chain Polymer

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    The two photon absorption spectrum has been measured in the 780–1600 nm range for a di‐alkyl‐amino‐nitro‐stilbene side‐chain polymer. A single two photon peak centered at 920 nm is observed with a peak two photon coefficient of 5.5 cm/GW. Bleaching via two photon absorption at this wavelength is investigated by measuring a refractive index change after an intensive exposure

    Synthesis, Characterisation and 3D Printing of an Isosorbide Based, Light Curable, Degradable Polymer for Potential Application in Maxillofacial Reconstruction

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    Although emergence of bone tissue engineering techniques has revolutionised the field of maxillofacial reconstruction, the successful translation of such products, especially concerning larger sized defects, still remains a significant challenge. Light curable methacrylate based polymers have ideal properties for bone repair. These materials are also suitable for 3D printing which can be applicable for restoration of both function and aesthetics. The main objective of this research was to synthesise a mechanically stable and biologically functional polymer for reconstruction of complex craniofacial defects. The experimental work initially involved synthesis of (((3R,3aR,6S,6aR)-hexahydrofuro[3,2-b]furan-3,6-diyl)bis(oxy))bis(ethane-2,1-diyl) bis((4-methyl-3-oxopent-4-en-1-yl)carbamate), CSMA-1, and ((((((((((((3R,3aR,6S,6aR)-hexahydrofuro[3,2-b]furan-3,6-diyl)bis(oxy))bis(ethane-2,1 diyl))bis(oxy))bis(carbonyl))bis(azanediyl))bis(methylene))bis(3,3,5-trimethylcyclohexane-5,1-diyl))bis(azanediyl))bis(carbonyl))bis(oxy))bis(ethane-2,1-diyl) bis(2-methylacrylate), CSMA-2; Nuclear Magnetic Resonance (NMR) analysis confirmed formation of the monomers and composite samples were fabricated respectively by exposing 11 mm diameter discs to blue light. Modulus of the tensile elasticity was tested using a biaxial flexural test and the values were found to be between 1 and 3 GPa in CMA-1, CSMA-2 and their composites. In vitro cell culture, using human Bone Marrow Derived Mesenchymal Stem Cells (BMSCs), confirmed non-toxicity of the samples and finally 3D printing allowed direct extrusion and setting of the bio ink into a mesh-like construct

    Monitoring Grape Berry Moth (Paralobesia viteana: Lepidoptera) in Commercial Vineyards using a Host Plant Based Synthetic Lure

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    For some Lepidopteran pests, such as the grape berry moth Paralobesia viteana (Clemens), poor correlation between males captured in traps baited with sex pheromone and oviposition activities of female moths has called into question the value of pheromone-based monitoring for these species. As an alternative, we compared the capture of female and male grape berry moth in panel traps baited with synthetic host volatiles with captures of males in pheromone-baited wing traps over two growing seasons in two blocks of grapes in a commercial vineyard in central New York. Lures formulated in hexane to release either 7-component or 13-component host volatile blends captured significantly more male and female grape berry moth on panel traps compared with the numbers captured on panel traps with hexane-only lures. For both sexes over both years, the same or more moths were captured in panel traps along the forest edge compared with the vineyard edge early in the season but this pattern was reversed by mid-season. Male moths captured in pheromone-baited wing traps also displayed this temporal shift in location. There was a significant positive correlation between captured males and females on panel traps although not between females captured on panel traps and males captured in pheromone-baited traps for both years suggesting pheromone traps do not accurately reflect either female or male activity. Male moths captured in pheromone traps indicated a large peak early in each season corresponding to first flight followed by lower and variable numbers that did not clearly indicate second and third flights. Panel trap data, combining males and females, indicated three distinct flights, with some overlap between the second and third flights. Peak numbers of moths captured on panel traps matched well with predictions of a temperature-based phenology model, especially in 2008. Although effective, panel traps baited with synthetic host lures were time consuming to deploy and maintain and captured relatively few moths making them impractical, in the current design, for commercial purpose

    Rapid Surface Oxidation as a Source of Surface Degradation Factor for Bi2Se3

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    Bi2Se3 is a topological insulator with metallic surface states residing in a large bulk bandgap. It is believed that Bi2Se3 gets additional n-type doping after exposure to atmosphere, thereby reducing the relative contribution of surface states in total conductivity. In this letter, transport measurements on Bi2Se3 nanoribbons provide additional evidence of such environmental doping process. Systematic surface composition analyses by X-ray photoelectron spectroscopy reveal fast formation and continuous growth of native oxide on Bi2Se3 under ambient conditions. In addition to n-type doping at the surface, such surface oxidation is likely the material origin of the degradation of topological surface states. Appropriate surface passivation or encapsulation may be required to probe topological surface states of Bi2Se3 by transport measurements
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