599 research outputs found

    Bundle pricing of inventories with stochastic demand

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    Cataloged from PDF version of article.We consider a retailer selling a fixed inventory of two perishable products over a finite horizon. Assuming Poisson arrivals and a bivariate reservation price distribution, we determine the optimal product and bundle prices that maximize the expected revenue. Our results indicate that the performances of mixed bundling, pure bundling and unbundled sales strategies heavily depend on the parameters of the demand process and the initial inventory levels. Bundling appears to be most effective with negatively correlated reservation prices and high starting inventory levels. When the starting inventory levels are equal and in excess of average demand, most of the benefits of bundling can be achieved through pure bundling. However, the mixed bundling strategy dominates the other two when the starting inventory levels are not equal. We also observe that an incorrect modeling of the reservation prices may lead to significant losses. The model is extended to allow for price changes during the selling horizon. It is shown that offering price bundles mid-season may be more effective than changing individual product prices. 2008 Elsevier B.V. All rights reserved

    Study of Eclipsing Binary and Multiple Systems in OB Associations: I. Ori OB1a - IM Mon

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    All available photometric and spectroscopic observations were collected and used as the basis of a detailed analysis of the close binary IM Mon. The orbital period of the binary was refined to 1.19024249(0.00000014) days. The Roche equipotentials, fractional luminosities (in (B, V) and H_p bands) and fractional radii for the component stars in addition to mass ratio q, inclination i of the orbit and the effective temperature T_eff of the secondary cooler less massive component were obtained by the analysis of light curves. IM Mon is classified to be a detached binary system in contrast to the contact configuration estimations in the literature. The absolute parameters of IM Mon were derived by the simultaneous solutions of light and radial velocity curves as M_1,2=5.50(0.24)M_o and 3.32(0.16)M_o, R1,2=3.15(0.04)R_o and 2.36(0.03)R_o, T_eff1,2=17500(350) K and 14500(550) K implying spectral types of B4 and B6.5 ZAMS stars for the primary and secondary components respectively. The modelling of the high resolution spectrum revealed the rotational velocities of the component stars as V_rot1=147(15) km/s and V_rot2=90(25) km/s. The photometric distance of 353(59) pc was found more precise and reliable than Hipparcos distance of 341(85) pc. An evolutionary age of 11.5(1.5) Myr was obtained for IM Mon. Kinematical and dynamical analysis support the membership of the young thin-disk population system IM Mon to the Ori OB1a association dynamically. Finally, we derived the distance, age and metallicity information of Ori OB1a sub-group using the information of IM Mon parameters.Comment: 26 pages, 5 figures and 6 tables, accepted for publication in Publication of the Astronomical Society of Japa

    Single-hole properties in the tt-JJ and strong-coupling models

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    We report numerical results for the single-hole properties in the tt-JJ model and the strong-coupling approximation to the Hubbard model in two dimensions. Using the hopping basis with over 10610^6 states we discuss (for an infinite system) the bandwidth, the leading Fourier coefficients in the dispersion, the band masses, and the spin-spin correlations near the hole. We compare our results with those obtained by other methods. The band minimum is found to be at (π/2,π/2\pi/2,\pi/2) for the tt-JJ model for 0.1t/J100.1 \leq t/J \leq 10, and for the strong-coupling model for 1t/J101 \leq t/J \leq 10. The bandwidth in both models is approximately 2J2J at large t/Jt/J, in rough agreement with loop-expansion results but in disagreement with other results. The strong-coupling bandwidth for t/J\agt6 can be obtained from the tt-JJ model by treating the three-site terms in first-order perturbation theory. The dispersion along the magnetic zone face is flat, giving a large parallel/perpendicular band mass ratio.Comment: 1 RevTeX file with epsf directives to include 8 .eps figures 8 figure files encoded using uufile

    Quasiparticle Dispersion of the 2D Hubbard Model: From an Insulator to a Metal

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    On the basis of Quantum-Monte-Carlo results the evolution of the spectral weight A(k,ω)A(\vec k, \omega) of the two-dimensional Hubbard model is studied from insulating to metallic behavior. As observed in recent photoemission experiments for cuprates, the electronic excitations display essentially doping-independent features: a quasiparticle-like dispersive narrow band of width of the order of the exchange interaction JJ and a broad valence- and conduction-band background. The continuous evolution is traced back to one and the same many-body origin: the doping-dependent antiferromagnetic spin-spin correlation.Comment: 11 pages, REVtex, 4 figures (in uuencoded postscript format

    Superconducting Order Parameter in Bi-Layer Cuprates: Occurrence of π\pi Phase Shifts in Corner Junctions

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    We study the order parameter symmetry in bi-layer cuprates such as YBaCuO, where interesting π\pi phase shifts have been observed in Josephson junctions. Taking models which represent the measured spin fluctuation spectra of this cuprate, as well as more general models of Coulomb correlation effects, we classify the allowed symmetries and determine their associated physical properties. π\pi phase shifts are shown to be a general consequence of repulsive interactions, independent of whether a magnetic mechanism is operative. While it is known to occur in d-states, this behavior can also be associated with (orthorhombic) s-symmetry when the two sub-band gaps have opposite phase. Implications for the magnitude of TcT_c are discussed.Comment: 5 pages, RevTeX 3.0, 9 figures (available upon request

    Does Fiscal Decentralization Promote Fiscal Discipline?

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    We investigate the efficiency and equity implications of a redistributive rule that takes into account both local tax collection efforts and deviation of local incomes from respective targets under alternative fiscal mechanisms. We show that, if the general budget constraint is binding, the proposed transfer rule leads to higher fiscal discipline under fiscal decentralization (FD) than under centralized redistribution. Although the centralized decision yields better income distribution than FD, FD also improves income distribution unambiguously when equalization across regions is targeted explicitly. When localities act strategically, the private sectors utility weight enhances the disciplinary effect of decentralization. © 2016 Taylor & Francis Group, LLC

    Bilateral Talus and Navicular Fractures accompanied with Unilateral Calcaneal Fracture: A Case Report

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    An 18-year old male patient, with a history of paragliding accident, sustaining a coronal shear fracture of the body of the talus, an anterior process fracture of the calcaneus extending to the calcaneocuboid joint and a nondisplaced navicular body fracture at the right foot and a displaced fracture of the navicular body accompanied with posteromedial process fracture of the talus at the left side was referred to our emergency clinic. For the right foot, the coronal plane fracture of the talar body was anatomically reduced and fixed with screws. For the left foot, screw fixation was performed through the lateral aspect to fix the large posteromedial fragment. Small bone fragments were removed from the left navicular fracture, and the main fragments were also fixed with screw. The talo-navicular joint was stabilised with a Kirschner wire. At 36 months follow-up, bilateral foot and ankle functions were satisfactory, Maryland scores of the right and left foot were 85 (good) and 90 (excellent), respectively, and the patient regained his full activity level by the 5th month postoperatively. With reference to the number and types of fractures in this one patient, we present a standard protocol for treatment of isolated talus, navicular and calcaneal fractures presenting together in a single foot injury

    Electronic spectrum in high-temperature cuprate superconductors

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    A microscopic theory for electronic spectrum of the CuO2 plane within an effective p-d Hubbard model is proposed. Dyson equation for the single-electron Green function in terms of the Hubbard operators is derived which is solved self-consistently for the self-energy evaluated in the noncrossing approximation. Electron scattering on spin fluctuations induced by kinematic interaction is described by a dynamical spin susceptibility with a continuous spectrum. Doping and temperature dependence of electron dispersions, spectral functions, the Fermi surface and the coupling constant are studied in the hole doped case. At low doping, an arc-type Fermi surface and a pseudogap in the spectral function are observed.Comment: 13 pages (revtex), 18 figures, to be published in JET

    One particle spectral weight of the three dimensional single band Hubbard model

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    Dynamic properties of the three-dimensional single-band Hubbard model are studied using Quantum Monte Carlo combined with the maximum entropy technique. At half-filling, there is a clear gap in the density of states and well-defined quasiparticle peaks at the top (bottom) of the lower (upper) Hubbard band. We find an antiferromagnetically induced weight above the naive Fermi momentum. Upon hole doping, the chemical potential moves to the top of the lower band where a robust peak is observed. Results are compared with spin-density-wave (SDW) mean-field and self consistent Born approximation results, and also with the infinite dimensional Hubbard model, and experimental photoemission (PES) for three dimensional transition-metal oxides.Comment: 11 pages, REVTeX, 16 figures included using psfig.sty. Ref.30 correcte
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