2,072 research outputs found

    Infinite Excess Entropy Processes with Countable-State Generators

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    We present two examples of finite-alphabet, infinite excess entropy processes generated by invariant hidden Markov models (HMMs) with countable state sets. The first, simpler example is not ergodic, but the second is. It appears these are the first constructions of processes of this type. Previous examples of infinite excess entropy processes over finite alphabets admit only invariant HMM presentations with uncountable state sets.Comment: 13 pages, 3 figures; http://csc.ucdavis.edu/~cmg/compmech/pubs/ieepcsg.ht

    Bioaccumulation of Microcystins by Freshwater Mussels in Mystic Lake and Middle Pond, MA

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    The UNH Center for Freshwater Biology investigated a possible relationship between a cyanobacteria bloom and a large-scale die-off of freshwater mussels in Mystic Lake and Middle Pond (Barnstable, MA). Four mussel species, Elliptio complanata (Eastern Elliptio), Pyganodon cataracta (Eastern Floater), Leptodea ochracea (Tidewater Mucket), and Lampsilis radiata (Eastern Lampmussel) (Nedeau, 2008), along with water samples, were collected from these lakes on August 9, 2010 (during bloom) and again on September 29 and October 8, 2010 (post-bloom). Hepatopancreas tissue, foot tissue, and water samples were tested for the cyanobacteria toxins, microcystins (MC), using ELISA techniques. MC concentrations in the hepatopancreas were generally higher (171.2 ng MC g-1 dry weight (dw)) than in the muscle (foot) tissue (55.8 ng MC g -1 dw) for each species. Average microcystin concentrations in mussels sampled during postbloom tissues were slightly lower (161.6 ng MC g-1 dw) than those collected during the cyanobacteria bloom (171.2 ng MC g1 dw). Live mussels were also subjected to a depuration experiment to determine the release of MC from mussels into the water. Mussels that were placed in cyanobacteria-free water depurated 61-90% MC within the first few days demonstrating their ability to release free MC-cyanotoxins into the lake water

    Novel mid-infrared dispersive wave generation in gas-filled PCF by transient ionization-driven changes in dispersion

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    Gas-filled hollow-core photonic crystal fibre (PCF) is being used to generate ever wider supercontinuum spectra, in particular via dispersive wave (DW) emission in the deep and vacuum ultraviolet, with a multitude of applications. DWs are the result of the resonant transfer of energy from a self-compressed soliton, a process which relies crucially on phase matching. It was recently predicted that, in the strong-field regime, the additional transient anomalous dispersion introduced by gas ionization would allow phase-matched DW generation in the mid-infrared (MIR)-something that is forbidden in the absence of free electrons. Here we report for the first time the experimental observation of such MIR DWs, embedded in a 4.7-octave-wide supercontinuum that uniquely reaches simultaneously to the vacuum ultraviolet, with up to 1.7 W of total average power

    Comportement du consommateur face à un risque endogène immédiat

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    L’objet de cet article est d’analyser le comportement du consommateur face à un bien courant dont la consommation génère un risque sanitaire pouvant se réaliser dans un bref délai, tels que les risques de toxi-infection d’origine alimentaire liés à la présence d’éléments nocifs. À partir d’un modèle simple, dans lequel la fonction de probabilité individuelle dépend de la quantité consommée, nous démontrons que l’endogénéisation du risque déforme les préférences du consommateur et conduit à leur non-convexité. Les équilibres de consommation et les fonctions de demande qui en résultent en sont affectés, selon le degré de sévérité perçu et la forme de la fonction subjective quantité-probabilité utilisée par le consommateur

    Attitude du consommateur face à un risque endogène immédiat

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    Date du colloque&nbsp;: 2009</p

    Proposal for a Council Regulation (EEC) derogating from Article 21 of Regulation (EEC) No 1035/72 on the common organization of the market in fruit and vegetables

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    We present the results of an experimental and numerical investigation into temporally nonlocal coherent interactions between ultrashort pulses, mediated by Raman coherence, in a gas-filled kagome-style hollow-core photonic-crystal fiber. A pump pulse first sets up the Raman coherence, creating a refractive index spatiotemporal grating in the gas that travels at the group velocity of the pump pulse. Varying the arrival time of a second, probe, pulse allows a high degree of control over its evolution as it propagates along the fiber through the grating. Of particular interest are soliton-driven effects such as self-compression and dispersive wave (DW) emission. In the experiments reported, a DW is emitted at ∼300 nm and exhibits a wiggling effect, with its central frequency oscillating periodically with pump-probe delay. The results demonstrate that a strong Raman coherence, created in a broadband guiding gas-filled kagome photonic-crystal fiber, can be used to control the nonlinear dynamics of ultrashort probe pulses, even in difficult-to-access spectral regions such as the deep and vacuum ultraviolet
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