4,659 research outputs found

    Reading inflation expectations from CPI futures

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    Consumer price indexes ; Inflation (Finance)

    Oil price volatility and U.S. macroeconomic activity

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    Oil shocks exert influence on macroeconomic activity through various channels, many of which imply a symmetric effect. However, the effect can also be asymmetric. In particular, sharp oil price changes-either increases or decreases-may reduce aggregate output temporarily because they delay business investment by raising uncertainty or induce costly sectoral resource reallocation. Consistent with these asymmetric-effect hypotheses, the authors find that a volatility measure constructed using daily crude oil futures prices has a negative and significant effect on future gross domestic product (GDP) growth over the period 1984-2004. Moreover, the effect becomes more significant after oil price changes are also included in the regression to control for the symmetric effect. The evidence here provides economic rationales for Hamilton's (2003) nonlinear oil shock measure: It captures overall effects, both symmetric and asymmetric, of oil price shocks on output.Petroleum products - Prices ; Macroeconomics

    Is the σ\sigma meson dynamically generated?

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    We study the problem whether the σ\sigma meson is generated `dynamically'. A pedagogical analysis on the toy O(N) linear sigma model is performed and we find that the large NcN_c limit and the mσ→∞m_\sigma\to \infty limit does not commute. The sigma meson may not necessarily be described as a dynamically generated resonance. On the contrary, the sigma meson may be more appropriately described by considering it as an explicit degree of freedom in the effective lagrangian.Comment: Contribution to ``Quark Confinement and Hadron Spectrum VII'', 2--7 Sept. 2006, Ponta Delgada, Acores, Portuga

    Spin interference and Fano effect in electron transport through a mesoscopic ring side-coupled with a quantum dot

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    We investigate the electron transport through a mesoscopic ring side-coupled with a quantum dot(QD) in the presence of Rashba spin-orbit(SO) interaction. It is shown that both the Fano resonance and the spin interference effects play important roles in the electron transport properties. As the QD level is around the Fermi energy, the total conductance shows typical Fano resonance line shape. By applying an electrical gate voltage to the QD, the total transmission through the system can be strongly modulated. By threading the mesoscopic ring with a magnetic flux, the time-reversal symmetry of the system is broken, and a spin polarized current can be obtained even though the incident current is unpolarized.Comment: 5 pages, 5 figure

    Confinement induced resonances in anharmonic waveguides

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    We develop the theory of anharmonic confinement-induced resonances (ACIR). These are caused by anharmonic excitation of the transverse motion of the center of mass (COM) of two bound atoms in a waveguide. As the transverse confinement becomes anisotropic, we find that the COM resonant solutions split for a quasi-1D system, in agreement with recent experiments. This is not found in harmonic confinement theories. A new resonance appears for repulsive couplings (a3D>0a_{3D}>0) for a quasi-2D system, which is also not seen with harmonic confinement. After inclusion of anharmonic energy corrections within perturbation theory, we find that these ACIR resonances agree extremely well with anomalous 1D and 2D confinement induced resonance positions observed in recent experiments. Multiple even and odd order transverse ACIR resonances are identified in experimental data, including up to N=4 transverse COM quantum numbers.Comment: 16 pages,6 fugure

    Is the f0(600)f_0(600) meson a dynamically generated resonance? -- a lesson learned from the O(N) model and beyond

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    O(N) linear σ\sigma model is solvable in the large NN limit and hence provides a useful theoretical laboratory to test various unitarization approximations. We find that the large NcN_c limit and the mσ→∞m_\sigma\to \infty limit do not commute. In order to get the correct large NcN_c spectrum one has to firstly take the large NcN_c limit. We argue that the f0(600)f_0(600) meson may not be described as generated dynamically. On the contrary, it is most appropriately described at the same level as the pions, i.e, both appear explicitly in the effective lagrangian. Actually it is very likely the σ\sigma meson responsible for the spontaneous chiral symmetry breaking in a lagrangian with linearly realized chiral symmetry.Comment: 15 pages, 3 figurs; references added; discussions slightly modified; revised version accepted by IJMP

    Spontaneously generated atomic entanglement in free space: reinforced by incoherent pumping

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    We study spontaneously generated entanglement (SGE) between two identical multilevel atoms in free space via vacuum-induced radiative coupling. We show that the SGE in two-atom systems may initially increase with time but eventually vanishes in the time scale determined by the excited state lifetime and radiative coupling strength between the two atoms. We demonstrate that a steady-state SGE can be established by incoherently pumping the excited states of the two-atom system. We have shown that an appropriate rate of incoherent pump can help producing optimal SGE. The multilevel systems offer us more chanel to establish entanglement. The system under consideration could be realized in a tight trap or atoms/ions doped in a solid substrate.Comment: have some difference with published version (please see PRA

    RNA-Based Compositions and Adjuvants for Prophylactic and Therapeutic Treatment

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    The present invention is directed towards an artificial RNA nano structure comprising multiple external strands of RNA, each external strand comprising about 40-50 nucleotides; one internal strand of RNA comprising more than about 50 nucleotides; the internal strands and external strands assembled to form a triangle nanostructure, a square nanostructure, or a polygon nanostructure and a pRNA three-way junction (3WJ) motif at each vertex of the nanostructure. Such nanostructure can be provided in a composition together with an adjuvant for use in inducing the production of high affinity neutralizing antibodies or inhibitory antibodies, inducing the production of cytokines, inducing an immune response in a subject, or a combination thereof

    Acoustic black holes from supercurrent tunneling

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    We present a version of acoustic black holes by using the principle of the Josephson effect. We find that in the case two superconductors AA and BB are separated by an insulating barrier, an acoustic black hole may be created in the middle region between the two superconductors. We discuss in detail how to describe an acoustic black hole in the Josephson junction and write the metric in the langauge of the superconducting electronics. Our final results infer that for big enough tunneling current and thickness of the junction, experimental verification of the Hawking temperature could be possible.Comment: 15pages,1 figure, to appear in IJMP

    Investigation of Printing‐Based Graded Bulk‐Heterojunction Organic Solar Cells

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    A 2‐step method involving the evaporation of solvent through surface encapsulation and induced alignment (ESSENCIAL) has been used to create a compositionally graded active layer of interspersed acceptor and donor domains by printing‐based technologies, which can be used to fabricate solar cells with higher performance than that from traditional bulk heterojunction fabrication methods. Herein, to clarify the fundamental mechanism of the performance improvement, a multi‐scale simulation has been conducted to compare solar cells resulting from these two types of processing. The multi‐scale simulation identified the underlying improvements of the ESSENCIAL morphology over traditional morphologies. Monte Carlo simulations obtained higher hole‐mobility values and lower monomolecular recombination rates for the ESSENCIAL‐fabricated cells that, in conjunction with the optical and electrical components, showed higher short‐circuit currents, fill factors, and efficiencies, as indicated experimentally. The simulation offers the unique ability to model the varied active layer compositions and elucidate the underlying solar cell physics of complex morphologies.Explaining the physics: A multi‐scale simulation composed of optical, Monte Carlo, and electrical simulations is used to identify and understand the improvements of a new, printing‐based morphology for organic solar cells. Organic solar cells with normal bulk‐heterojunction morphologies and the new printing‐based morphologies are simulated and compared to identify the latter's fundamental improvements.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/111163/1/414_ftp.pd
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