10,583 research outputs found

    Entanglement and spin squeezing properties for three bosons in two modes

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    We discuss the canonical form for a pure state of three identical bosons in two modes, and classify its entanglement correlation into two types, the analogous GHZ and the W types as well known in a system of three distinguishable qubits. We have performed a detailed study of two important entanglement measures for such a system, the concurrence C\mathcal{C} and the triple entanglement measure Ď„\tau. We have also calculated explicitly the spin squeezing parameter Îľ\xi and the result shows that the W state is the most ``anti-squeezing'' state, for which the spin squeezing parameter cannot be regarded as an entanglement measure.Comment: 7 pages, 6 figures; corrected figure sequence. Thanks to Dr. Han P

    Cerenkov Line Emission as a Possible Mechanism of X-ray Lines in Gamma-ray Bursts

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    The recent discoveries of X-ray lines in the afterglows of gamma-ray bursts (GRBs) provide significant clues to the nature of GRB progenitors and central environments. However, the iron line interpretation by fluorescence or recombination mechanism requires a large amount of iron material. We argue that the very strong iron line could be attributed to an alternative mechanism: Cerenkov line emission since relativistic electrons and dense medium exist near GRB sites. Therefore, the broad iron lines are expected, and line intensity will be nearly independent of the iron abundance, the medium with the anomalously high Fe abundance is not required.Comment: 4 pages, revised version accepted for the publication in ApJ

    Nonionic surfactant Brij35 effects on toluene biodegradation in a composite bead biofilter

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    Nonionic surfactant effects on the toluene dissolved in the water phase and biodegradation kinetic behaviors of toluene in a composite bead biofilter were investigated. The toluene dissolved in the water phase was enhanced by the addition of surfactant into aqueous solution and the enhancing effect was more pronounced in the surfactant concentration less than critical micelle concentration. For the microbial growth process, the microbial growth rate was inhibited at higher surfactant content and thedegree of inhibitive effect was more pronounced at lower inlet concentration. The microbial growth rate was inhibited at higher inlet concentration. Zero-order kinetic with the diffusion limitation could beregarded as the most adequate biochemical reaction model. For the biochemical reaction process, the biochemical reaction rate was also inhibited at higher surfactant content and the degree of inhibitiveeffect was more pronounced at lower inlet concentration. The biochemical reaction rate was also inhibited at higher inlet concentration. The maximum elimination capacity decreased with increasing surfactant content and it was in the range of 17.41 to 26.12 g C h-1 m-3 bed volume. The addition of surfactant into filter material was unfavorable for toluene degraded by the microbial

    Synthesis, characterization and crystal structure of a dioxomolybdenum(VI) complex derived from N’-(2-hydroxy-4-diethaylaminobenzylidene)-4-hydroxybenzohydrazide

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    Reaction of [MoO2(acac)2] (where acac = acetylacetonate) with N’-(2-hydroxy-4-diethaylaminobenzylidene)-4-hydroxybenzohydrazide (H2L) in methanol afforded a methanol-coordinated mononuclear molybdenum(VI) oxo complex, [MoO2L(MeOH)]. Crystal and molecular structure of the complex were determined by single crystal X-ray diffraction method. The complex was further characterized by elemental analysis and FT-IR spectra. Single crystal X-ray structural studies indicate that the hydrazone ligand coordinates to the MoO2 core through enolate oxygen, phenolate oxygen and azomethine nitrogen. The Mo atom in the complex is in octahedral coordination. Thermal stability of the complex has also been studied. KEY WORDS: Molybdenum complex, Hydrazone ligand, Crystal structure, X-ray diffraction, Thermal property Bull. Chem. Soc. Ethiop. 2014, 28(3), 409-414.DOI: http://dx.doi.org/10.4314/bcse.v28i3.1

    Online Station Assignment for Electric Vehicle Battery Swapping

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    This paper investigates the online station assignment for (commercial) electric vehicles (EVs) that request battery swapping from a central operator, i.e., in the absence of future information a battery swapping service station has to be assigned instantly to each EV upon its request. Based on EVs' locations, the availability of fully-charged batteries at service stations in the system, as well as traffic conditions, the assignment aims to minimize cost to EVs and congestion at service stations. Inspired by a polynomial-time offline solution via a bipartite matching approach, we develop an efficient and implementable online station assignment algorithm that provably achieves the tight (optimal) competitive ratio under mild conditions. Monte Carlo experiments on a real transportation network by Baidu Maps show that our algorithm performs reasonably well on realistic inputs, even with a certain amount of estimation error in parameters

    Online Station Assignment for Electric Vehicle Battery Swapping

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    This paper investigates the online station assignment for (commercial) electric vehicles (EVs) that request battery swapping from a central operator, i.e., in the absence of future information a battery swapping service station has to be assigned instantly to each EV upon its request. Based on EVs' locations, the availability of fully-charged batteries at service stations in the system, as well as traffic conditions, the assignment aims to minimize cost to EVs and congestion at service stations. Inspired by a polynomial-time offline solution via a bipartite matching approach, we develop an efficient and implementable online station assignment algorithm that provably achieves the tight (optimal) competitive ratio under mild conditions. Monte Carlo experiments on a real transportation network by Baidu Maps show that our algorithm performs reasonably well on realistic inputs, even with a certain amount of estimation error in parameters

    Does the Iron Kα_{\alpha} Line of Active Galactic Nuclei Arise from the Cerenkov Line-like Radiation?

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    When thermal relativistic electrons with isotropic distribution of velocities move in a gas region, or impinge upon the surface of a cloud that consists of a dense gas or doped dusts, the Cerenkov effect produces peculiar atomic or ionic emission lines -- the Cerenkov line-like radiation. This newly recognized emission mechanism may find wide applications in high-energy astrophysics. In this paper, we tentatively adopt this new line emission mechanism to discuss the origin of iron Kα_{\alpha} feature of AGNs. Motivation of this research is to attempt a solution to a problem encountered by the ``disk-fluorescence line'' model, i.e. the lack of temporal response of the observed iron Kα_{\alpha} line flux to the changes of the X-ray continuum flux. If the Cerenkov line emission is indeed responsible significantly for the iron Kα_{\alpha} feature, the conventional scenario around the central supermassive black holes of AGNs would need to be modified to accommodate more energetic, more violent and much denser environments than previously thought.Comment: 22 pages, 4 figures, 1 table. ApJ in press (December
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