17,447 research outputs found

    Seasonal unit root tests for the monthly container transshipment of the port of Hamburg

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    This paper investigates the seasonal behaviour of monthly container transshipment data of the port of Hamburg. The test procedures of Franses and Beaulieu-Miron are used to examine the presence of multiple unit roots in the monthly seasonal frequencies. This is followed by the Canova-Hansen procedure for testing the stability of the seasonal patterns. Evidence suggests that these monthly transshipment data are non-stationary at frequency zero and have no seasonal unit roots. The analysis shows that the process is in the long run integrated of order one and that the seasonal variations can be modelled by dummy variables. Using the deterministic seasonality found here, further analysis and forecasting of container throughput of the port of Hamburg can be improved for market participants like containership lines. -- Die Analyse betrachtet das saisonale Muster des monatlichen Containerumschlags im Hamburger Hafen von 1993 bis 2008. Dabei werden die Tests von Franses und Beaulieu-Miron zur PrĂŒfung auf multiple Einheitswurzeln und von Canova-Hansen zur StabilitĂ€tsprĂŒfung der saisonalen Schwankungen benutzt. Es zeigt sich, dass im betrachteten Zeitraum der Containerumschlag nichtstationĂ€r bei Frequenz Null ist und keine saisonale Einheitswurzeln vorliegen. Die Daten sind integriert vom Grad Eins (stochastischer Trend), und die saisonalen Variationen lassen sich durch Dummy-Variable modellieren. Diese Ergebnisse können bei der Analyse und Prognose des Containerumschlags im Hamburger Hafen fĂŒr Marktteilnehmer, wie z.B. Reedereien oder Hafengesellschaften, nĂŒtzlich sein.

    Randomized crossover comparison of proportional assist ventilation and patient-triggered ventilation in extremely low birth weight infants with evolving chronic lung disease

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    Background: Refinement of ventilatory techniques remains a challenge given the persistence of chronic lung disease of preterm infants. Objective: To test the hypothesis that proportional assist ventilation ( PAV) will allow to lower the ventilator pressure at equivalent fractions of inspiratory oxygen (FiO(2)) and arterial hemoglobin oxygen saturation in ventilator-dependent extremely low birth weight infants in comparison with standard patient-triggered ventilation ( PTV). Methods: Design: Randomized crossover design. Setting: Two level-3 university perinatal centers. Patients: 22 infants ( mean (SD): birth weight, 705 g ( 215); gestational age, 25.6 weeks ( 2.0); age at study, 22.9 days ( 15.6)). Interventions: One 4- hour period of PAV was applied on each of 2 consecutive days and compared with epochs of standard PTV. Results: Mean airway pressure was 5.64 ( SD, 0.81) cm H2O during PAV and 6.59 ( SD, 1.26) cm H2O during PTV ( p < 0.0001), the mean peak inspiratory pressure was 10.3 ( SD, 2.48) cm H2O and 15.1 ( SD, 3.64) cm H2O ( p < 0.001), respectively. The FiO(2) ( 0.34 (0.13) vs. 0.34 ( 0.14)) and pulse oximetry readings were not significantly different. The incidence of arterial oxygen desaturations was not different ( 3.48 ( 3.2) vs. 3.34 ( 3.0) episodes/ h) but desaturations lasted longer during PAV ( 2.60 ( 2.8) vs. 1.85 ( 2.2) min of desaturation/ h, p = 0.049). PaCO2 measured transcutaneously in a subgroup of 12 infants was similar. One infant met prespecified PAV failure criteria. No adverse events occurred during the 164 cumulative hours of PAV application. Conclusions: PAV safely maintains gas exchange at lower mean airway pressures compared with PTV without adverse effects in this population. Backup conventional ventilation breaths must be provided to prevent apnea-related desaturations. Copyright (c) 2007 S. Karger AG, Base

    Plasmons, plasminos and Landau damping in a quasiparticle model of the quark-gluon plasma

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    A phenomenological quasiparticle model is surveyed for 2+1 quark flavors and compared with recent lattice QCD results. Emphasis is devoted to the effects of plasmons, plasminos and Landau damping. It is shown that thermodynamic bulk quantities, known at zero chemical potential, can uniquely be mapped towards nonzero chemical potential by means of a thermodynamic consistency condition and a stationarity condition.Comment: Sep. 2007. 13 pp. Invited talk given at Zimanyi 75 Memorial Workshop on Hadronic and Quark Matter, Budapest, Hungary, 2-4 Jul. 2007; reviewed and published versio

    Plasmons, plasminos and Landau damping in a quasiparticle model of the quark-gluon plasma

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    A phenomenological quasiparticle model is surveyed for 2+1 quark flavors and compared with recent lattice QCD results. Emphasis is devoted to the effects of plasmons, plasminos and Landau damping. It is shown that thermodynamic bulk quantities, known at zero chemical potential, can uniquely be mapped towards nonzero chemical potential by means of a thermodynamic consistency condition and a stationarity condition.Comment: Sep. 2007. 13 pp. Invited talk given at Zimanyi 75 Memorial Workshop on Hadronic and Quark Matter, Budapest, Hungary, 2-4 Jul. 2007; reviewed and published versio

    Socioeconophysics: Opinion Dynamics for number of transactions and price, a trader based model

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    Involving effects of media, opinion leader and other agents on the opinion of individuals of market society, a trader based model is developed and utilized to simulate price via supply and demand. Pronounced effects are considered with several weights and some personal differences between traders are taken into account. Resulting time series and probabilty distribution function involving a power law for price come out similar to the real ones.Comment: will be published in IJMPC 17 (2006

    Adiabatic pumping in the quasi-one-dimensional triangle lattice

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    We analyze the properties of the quasi-one-dimensional triangle lattice emphasizing the occurrence of flat bands and band touching via the tuning of the lattice hopping parameters and on-site energies. The spectral properties of the infinite system will be compared with the transmission through a finite piece of the lattice with attached semi-infinite leads. Furthermore, we investigate the adiabatic pumping properties of such a system: depending on the transmission through the lattice, this results in nonzero integer charge transfers or transfers that increase linearly with the lattice size

    XPS characterization of silver electrodes and catalyst for oxygen reduction

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    The combined analysis of the silver GDE using an ex-situ surface sensitive technique (XPS) and in-situ electrochemical measurements (EIS, CV) show that the performance of the silver GDE is significantly influenced by the degree of degradation of the electrodes, e. g., the reduction of the active surface due to the decomposition of the PTFE. These findings indicate a different degree of decomposition of the PTFE on the on the GDE

    Strange hadronic stellar matter within the Brueckner-Bethe-Goldstone theory

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    In the framework of the non-relativistic Brueckner-Bethe-Goldstone theory, we derive a microscopic equation of state for asymmetric and ÎČ\beta-stable matter containing Σ−\Sigma^- and Λ\Lambda hyperons. We mainly study the effects of three-body forces (TBFs) among nucleons on the hyperon formation and the equation of state (EoS). We find that, when TBFs are included, the stellar core is almost equally populated by nucleons and hyperons. The resulting EoS, which turns out to be extremely soft, has been used in order to calculate the static structure of neutron stars. We obtain a value of the maximum mass of 1.26 solar masses (1 solar mass Mo≃1.99⋅1033gM_o \simeq 1.99 \cdot 10^{33} g). Stellar rotations increase this value by about 12%.Comment: 4 pages, Latex, 2 figures included. To appear in the Proceedings of '' Bologna 2000 - Structure of the Nucleus at the Dawn of the Century'', May 29- June 3, 2000, Bologna, Ital
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