8,829 research outputs found

    Comparison Between Geese, Peking Ducks and Mallards in Ability to Digest Common Rye-Grass

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    The aim of this digestibility experiment was to observe the differences between geese, peking ducks and mallards to digest common ryegrass (Lolium perenne L.). Adult birds were used for the trials. The grass was frozen after harvesting, stored until the experimental period and fed in fresh constitution. The birds were reared in special single cages and had free access to water and grass. Geese have the best adapted digestive tract of all waterfowl species to consume and digest high-fibre feedstuffs. Peking ducks are able to consume a lot of grass and it seems the digestibility values are similar to geese. The acceptance of mallards for grass is low but the feed value appears not strongly different from geese and peking ducks

    Recent Decisions

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    Biologic Therapies for Severe Asthma

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    Biologic Therapies for Severe Asthma Patients with severe asthma are at increased risk for a decreased quality of life, fixed airway obstruction, hospitalization, and death. Biologics may be required to reduce the disease burden. This review discusses the mechanisms, efficacy, and safety of biologics for severe asthma

    Nonlocal First-Order Hamilton-Jacobi Equations Modelling Dislocations Dynamics

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    We study nonlocal first-order equations arising in the theory of dislocations. We prove the existence and uniqueness of the solutions of these equations in the case of positive and negative velocities, under suitable regularity assumptions on the initial data and the velocity. These results are based on new L1L^1-type estimates on the viscosity solutions of first-order Hamilton-Jacobi Equations appearing in the so-called ``level-sets approach''. Our work is inspired by and simplifies a recent work of Alvarez, Cardaliaguet and Monneau

    The bisymplectomorphism group of a bounded symmetric domain

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    An Hermitian bounded symmetric domain in a complex vector space, given in its circled realization, is endowed with two natural symplectic forms: the flat form and the hyperbolic form. In a similar way, the ambient vector space is also endowed with two natural symplectic forms: the Fubini-Study form and the flat form. It has been shown in arXiv:math.DG/0603141 that there exists a diffeomorphism from the domain to the ambient vector space which puts in correspondence the above pair of forms. This phenomenon is called symplectic duality for Hermitian non compact symmetric spaces. In this article, we first give a different and simpler proof of this fact. Then, in order to measure the non uniqueness of this symplectic duality map, we determine the group of bisymplectomorphisms of a bounded symmetric domain, that is, the group of diffeomorphisms which preserve simultaneously the hyperbolic and the flat symplectic form. This group is the direct product of the compact Lie group of linear automorphisms with an infinite-dimensional Abelian group. This result appears as a kind of Schwarz lemma.Comment: 19 pages. Version 2: minor correction

    On the Large Time Behavior of Solutions of Hamilton-Jacobi Equations Associated with Nonlinear Boundary Conditions

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    In this article, we study the large time behavior of solutions of first-order Hamilton-Jacobi Equations, set in a bounded domain with nonlinear Neumann boundary conditions, including the case of dynamical boundary conditions. We establish general convergence results for viscosity solutions of these Cauchy-Neumann problems by using two fairly different methods : the first one relies only on partial differential equations methods, which provides results even when the Hamiltonians are not convex, and the second one is an optimal control/dynamical system approach, named the "weak KAM approach" which requires the convexity of Hamiltonians and gives formulas for asymptotic solutions based on Aubry-Mather sets

    HST/NICMOS Observations of Fast Infrared Flickering in the Microquasar GRS 1915+105

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    We report infrared observations of the microquasar GRS 1915+105 using the NICMOS instrument of the Hubble Space Telescope during 9 visits in April-June 2003. During epochs of high X-ray/radio activity near the beginning and end of this period, we find that the 1.871.87 \um infrared flux is generally low (2\sim 2 mJy) and relatively steady. However, during the X-ray/radio ``plateau'' state between these epochs, we find that the infrared flux is significantly higher (46\sim 4-6 mJy), and strongly variable. In particular, we find events with amplitudes 2030\sim 20-30% occurring on timescales of 1020\sim 10-20s (e-folding timescales of 30\sim 30s). These flickering timescales are several times faster than any previously-observed infrared variability in GRS 1915+105 and the IR variations exceed corresponding X-ray variations at the same (8s\sim 8s) timescale. These results suggest an entirely new type of infrared variability from this object. Based on the properties of this flickering, we conclude that it arises in the plateau-state jet outflow itself, at a distance <2.5<2.5 AU from the accretion disk. We discuss the implications of this work and the potential of further flickering observations for understanding jet formation around black holes.Comment: 19 pages, incl. 4 figures; accepted for publication in Ap

    V1647 Ori (IRAS 05436-0007) in Outburst: the First Three Months

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    We report on photometric (BVRIJHK) and low dispersion spectroscopic observations of V1647 Ori, the star that drives McNeil's Nebula, between 10 February and 7 May 2004. The star is photometrically variable atop a general decline in brightness of about 0.3-0.4 magnitudes during these 87 days. The spectra are featureless, aside from H-alpha and the Ca II infrared triplet in emission, and a Na I D absorption feature. The Ca II triplet line ratios are typical of young stellar objects. The H-alpha equivalent width may be modulated on a period of about 60 days. The post-outburst extinction appears to be less than 7 mag. The data are suggestive of an FU Orionis-like event, but further monitoring will be needed to definitively characterize the outburst.Comment: Accepted for publication in the Astronomical Journa

    Large deviations in boundary-driven systems: Numerical evaluation and effective large-scale behavior

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    We study rare events in systems of diffusive fields driven out of equilibrium by the boundaries. We present a numerical technique and use it to calculate the probabilities of rare events in one and two dimensions. Using this technique, we show that the probability density of a slowly varying configuration can be captured with a small number of long wave-length modes. For a configuration which varies rapidly in space this description can be complemented by a local equilibrium assumption

    Auxiliary master equation for nonequilibrium dual-fermion approach

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    We introduce auxiliary quantum master equation - dual fermion approach (QME-DF) and argue that it presents a convenient way to describe steady-states of correlated impurity systems. The combined scheme yields an expansion around a reference much closer to the true nonequilibrium state than in the original dual fermion formulation. In steady-state situations, the scheme is numerically cheaper and allows to avoid long time propagation of previous considerations. Anderson impurity is used as a test model. The QME-DF simulations are compared with numerically exact tdDMRG results.Comment: 8 pages, 4 figure
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