5,724 research outputs found

    Revivification of confinement resonances in the photoionization of AA@C60_{60} endohedral atoms far above thresholds

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    It is discovered theoretically that significant confinement resonances in an nlnl photoionization of a \textit{multielectron} atom AA encaged in carbon fullerenes, A@C60_{60}, may re-appear and be strong at photon energies far exceeding the nlnl ionization threshold, as a general phenomenon. The reasons for this phenomenon are unraveled. The Ne 2p2p photoionization of the endohedral anion Ne@C605−_{60}^{5-} in the photon energy region of about a thousand eV above the 2p2p threshold is chosen as case study.Comment: 3 pages, 1 figure, Revtex

    Non-cooperative joint replenishment under asymmetric information

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    Cataloged from PDF version of article.We consider jointly replenishing n ex-ante identical firms that operate under an EOQ like setting using a non-cooperative game under asymmetric information. In this game, each firm, upon being privately informed about its demand rate (or inventory cost rate), submits a private contribution to an intermediary that specifies how much it is willing to pay for its replenishment per unit of time and the intermediary determines the maximum feasible frequency for the joint orders that would finance the fixed replenishment cost. We show that a Bayesian Nash equilibrium exists and characterize the equilibrium in this game. We also show that the contributions are monotone increasing in each firm’s type. We finally conduct a numerical study to compare the equilibrium to solutions obtained under independent and cooperative ordering, and under full information. The results show that while information asymmetry eliminates free-riding in the contributions game, the resulting aggregate contributions are not as high as under full information, leading to higher aggregate costs. 2013 Elsevier B.V. All rights reserved

    Multi-period supplier selection under price uncertainty

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    Cataloged from PDF version of article.We consider a problem faced by a procurement manager who needs to purchase a large volume of multiple items over multiple periods from multiple suppliers that provide base prices and discounts. Discounts are contingent on meeting various conditions on total volume or spend, and some are tied to future realizations of random events that can be mutually verified. We formulate a scenario-based multi-stage stochastic optimization model that allows us to consider random events such as a drop in price because of the most favoured customer clauses, a price change in the spot market or a new discount offer. We propose certainty-equivalent heuristics and evaluate the regret of using them. We use our model for three bidding events of a large manufacturing company. The results show that considering most favored customer clauses in supplier offers may create substantial savings that may surpass the savings from regular discount offers

    High precision determination of the Q2Q^2-evolution of the Bjorken Sum

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    We present a significantly improved determination of the Bjorken Sum for 0.6≤Q2≤\leq Q^{2}\leq4.8 GeV2^{2} using precise new g1pg_{1}^{p} and g1dg_{1}^{d} data taken with the CLAS detector at Jefferson Lab. A higher-twist analysis of the Q2Q^{2}-dependence of the Bjorken Sum yields the twist-4 coefficient f2p−n=−0.064±0.009±0.0360.032f_{2}^{p-n}=-0.064 \pm0.009\pm_{0.036}^{0.032}. This leads to the color polarizabilities χEp−n=−0.032±0.024\chi_{E}^{p-n}=-0.032\pm0.024 and χBp−n=0.032±0.013\chi_{B}^{p-n}=0.032\pm0.013. The strong force coupling is determined to be \alpha_{s}^{\overline{\mbox{ MS}}}(M_{Z}^{2})=0.1124\pm0.0061, which has an uncertainty a factor of 1.5 smaller than earlier estimates using polarized DIS data. This improvement makes the comparison between αs\alpha_{s} extracted from polarized DIS and other techniques a valuable test of QCD.Comment: Published in Phys. Rev. D. V1: 8 pages, 3 figures. V2: Updated references; Included threshold matching in \alpha_s evolution. Corrected a typo on the uncertainty for \Lambda_QCD. V3: Published versio

    Phenytoin-induced rhabdomyolysis

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    Rhabdomyolysis is a potentially life-threatening syndrome that can develop from a variety of causes. The most common causes are muscle injury, alcohol abuse, drugs, toxins and increased muscular activity. Phenytoin is one of the drugs that rarely cause rhabdomyolysis. We present the case of a man who developed rhabdomyolysis following phenytoin treatment

    Amyloid-like peptide nanofiber templated titania nanostructures as dye sensitized solar cell anodic materials

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    Cataloged from PDF version of article.One-dimensional titania nanostructures can serve as a support for light absorbing molecules and result in an improvement in the short circuit current (Jsc) and open circuit voltage (Voc) as a nanostructured and high-surface-area material in dye-sensitized solar cells. Here, self-assembled amyloid-like peptide nanofibers were exploited as an organic template for the growth of one-dimensional titania nanostructures. Nanostructured titania layers were utilized as anodic materials in dye sensitized solar cells (DSSCs). The photovoltaic performance of the DSSC devices was assessed and an enhancement in the overall cell performance compared to unstructured titania was observed. © 2013 The Royal Society of Chemistry

    Precise determination of the deuteron spin structure at low to moderate Q(2) with CLAS and extraction of the neutron contribution

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    We present the final results for the deuteron spin structure functions obtained from the full data set collected in 2000-2001 with Jefferson Lab\u27s continuous electron beam accelerator facility (CEBAF) using the CEBAF large acceptance spectrometer (CLAS). Polarized electrons with energies of 1.6, 2.5, 4.2, and 5.8 GeV were scattered from deuteron ((ND3)-N-15) targets, dynamically polarized along the beam direction, and detected with CLAS. From the measured double-spin asymmetry, the virtual photon absorption asymmetry A(1)(d) and the polarized structure function g(1)(d) were extracted over a wide kinematic range (0.05 GeV2 \u3c Q(2) \u3c 5 GeV2 and 0.9 GeV \u3c W \u3c 3 GeV). We use an unfolding procedure and a parametrization of the corresponding proton results to extract from these data the polarized structure functions A(1)(n) and g(1)(n) of the (bound) neutron, which are so far unknown in the resonance region, W \u3c 2 GeV. We compare our final results, including several moments of the deuteron and neutron spin structure functions, with various theoretical models and expectations, as well as parametrizations of the world data. The unprecedented precision and dense kinematic coverage of these data can aid in future extractions of polarized parton distributions, tests of perturbative QCD predictions for the quark polarization at large x, a better understanding of quark-hadron duality, and more precise values for higher-twist matrix elements in the framework of the operator product expansion

    Ascending Combinatorial Auctions with Risk Averse Bidders

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    Ascending combinatorial auctions are being used in an increasing number of spectrum sales worldwide, as well as in other multi-item markets in procurement and logistics. Much research has focused on pricing and payment rules in such ascending auctions. However, recent game-theoretical research has shown that such auctions can even lead to inefficient perfect Bayesian equilibria with risk-neutral bidders. There is a fundamental free-rider problem without a simple solution, raising the question whether ascending combinatorial auctions can be expected to be efficient in the field. Risk aversion is arguably a significant driver of bidding behavior in high-stakes auctions. We analyze the impact of risk aversion on equilibrium bidding strategies and efficiency in a threshold problem with one global and several local bidders. Due to the underlying free-rider problem, the impact of risk-aversion on equilibrium bidding strategies of local bidders is not obvious. We characterize the necessary and sufficient conditions for the perfect Bayesian equilibria of the ascending auction mechanism to have the local bidders to drop at the reserve price. Interestingly, in spite of the free-riding opportunities of local bidders, risk-aversion reduces the scope of the non-bidding equilibrium. The results help explain the high efficiency of ascending combinatorial auctions observed in the lab. © 2015, Springer Science+Business Media Dordrecht
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