6,684 research outputs found

    Dual characterization of critical fluctuations: Density functional theory & nonlinear dynamics close to a tangent bifurcation

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    We improve on the description of the relationship that exists between critical clusters in thermal systems and intermittency near the onset of chaos in low-dimensional systems. We make use of the statistical-mechanical language of inhomogeneous systems and of the renormalization group (RG) method in nonlinear dynamics to provide a more accurate, formal, approach to the subject. The description of this remarkable correspondence encompasses, on the one hand, the density functional formalism, where classical and quantum mechanical analogues match the procedure for one-dimensional clusters, and, on the other, the RG fixed-point map of functional compositions that captures the essential dynamical behavior. We provide details of how the above-referred theoretical approaches interrelate and discuss the implications of the correspondence between the high-dimensional (degrees of freedom) phenomenon and low-dimensional dynamics.Comment: 8 figure

    Massive envelopes and filaments in the NGC 3603 star forming region

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    The formation of massive stars and their arrival on the zero-age main-sequence occurs hidden behind dense clouds of gas and dust. In the giant Hii region NGC 3603, the radiation of a young cluster of OB stars has dispersed dust and gas in its vicinity. At a projected distance of 2:5 pc from the cluster, a bright mid-infrared (mid-IR) source (IRS 9A) had been identified as a massive young stellar object (MYSO), located on the side of a molecular clump (MM2) of gas facing the cluster. We investigated the physical conditions in MM2, based on APEX sub-mm observations using the SABOCA and SHFI instruments, and archival ATCA 3 mm continuum and CS spectral line data. We resolved MM2 into several compact cores, one of them closely associated with IRS 9A. These are likely infrared dark clouds as they do not show the typical hot-core emission lines and are mostly opaque against the mid-IR background. The compact cores have masses of up to several hundred times the solar mass and gas temperatures of about 50 K, without evidence of internal ionizing sources. We speculate that IRS 9A is younger than the cluster stars, but is in an evolutionary state after that of the compact cores

    Performance of two transferred modules in the Lagunera Region: Water relations

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    Water policy / Performance / Privatization / Irrigation systems / Operations / Maintenance / Irrigation efficiency / Water users' associations / Water rights / Water allocation / Water supply / Water distribution

    Lifetime Measurement of the 8s Level in Francium

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    We measure the lifetime of the 8s level on a magneto-optically trapped sample of ^{210}Fr atoms with time-correlated single-photon counting. The 7P_{1/2} state serves as the resonant intermediate level for two-photon excitation of the 8s level completed with a 1300 nm laser. Analysis of the fluorescence decay through the the 7P_{3/2} level gives 53.30 +- 0.44 ns for the 8s level lifetime.Comment: 4 pages, 4 figure

    Breeding for improved responsiveness to arbuscular mycorrhizal fungi in onion

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    Arbuscular mycorrhizal fungi (AMF) play an important role in the uptake of nutrients and water from soil. Onions, Allium cepa L., are plants with a shallow root system. As a result, onion plants need a lot of fertiziler for their growth. Furthermore, onion plants are sensitive to drought. The aim of the current research project is to study the beneficial effect of mycorrhizal fungi on the growth and development of Allium species and to determine whether it is possible to improve onions for mycorrhizal responsiveness by means of breeding. Variation among Allium species and segregation observed in a interspecific tri-hybrid population indicate that selection and thus breeding for high responsiveness to AMF is possible
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