4,531 research outputs found

    An Ecosystem Dynamics Model of Monterey Bay, California

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    Monterey Bay is an upwelling region with high biological productivity in the California Coastal Current System. Several moorings, developed and maintained by the Monterey Bay Aquarium Research Institute (MBARI), have produced a long-term, highquality time series oceanographic data set for the Monterey Bay. The data set has revealed a more comprehensive picture of physical-biological interaction on seasonal and interannual variability. To improve our understanding of how the marine ecosystem responds to physical forcing, especially upwelling, an open ocean ecosystem model was modified for the Monterey Bay upwelling region. The result was a nine-component ecosystem model of Monterey Bay, which produced simulated results comparable to the observations. The model included three nutrients (silicate, nitrate, and ammonia), two phytoplankton groups (small phytoplankton and diatoms), two zooplankton grazers (microzooplankton and mesozooplankton), and two detrital pools (silicon and nitrogen). The observed upwelling velocity, nutrient concentrations at the base of the euphotic zone (40m), and solar radiation at the ocean surface were used to force the ecosystem model. Through model and data comparison, as well as sensitivity studies testing ecosystem parameters, the model was capable of detailing the seasonal cycle of nutrient dynamics and phytoplankton productivity, as well as interannual variability, including El Nifio Southern Oscillation (ENSO) impacts on biological productivity in the Monterey Bay

    Evolution of the Kondo resonance feature and its relationship to spin-orbit coupling across the quantum critical point in Ce2Rh{1-x}CoxSi3

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    We investigate the evolution of the electronic structure of Ce2Rh{1-x}CoxSi3 as a function of x employing high resolution photoemission spectroscopy. Co substitution at the Rh sites in antiferromagnetic Ce2RhSi3 leads to a transition from an antiferromagnetic system to a Kondo system, Ce2CoSi3 via the Quantum Critical Point (QCP). High resolution photoemission spectra reveal distinct signature of the Kondo resonance feature (KRF) and its spin orbit split component (SOC) in the whole composition range indicating finite Kondo temperature scale at the quantum critical point. We observe that the intensity ratio of the Kondo resonance feature and its spin orbit split component, KRF/SOC gradually increases with the decrease in temperature in the strong hybridization limit. The scenario gets reversed if the Kondo temperature becomes lower than the magnetic ordering temperature. While finite Kondo temperature within the magnetically ordered phase indicates applicability of the spin density wave picture at the approach to QCP, the dominant temperature dependence of the spin-orbit coupled feature suggests importance of spin-orbit interactions in this regime.Comment: 6 figure

    On the Quantum Invariant for the Spherical Seifert Manifold

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    We study the Witten--Reshetikhin--Turaev SU(2) invariant for the Seifert manifold S3/ΓS^3/\Gamma where Γ\Gamma is a finite subgroup of SU(2). We show that the WRT invariants can be written in terms of the Eichler integral of the modular forms with half-integral weight, and we give an exact asymptotic expansion of the invariants by use of the nearly modular property of the Eichler integral. We further discuss that those modular forms have a direct connection with the polyhedral group by showing that the invariant polynomials of modular forms satisfy the polyhedral equations associated to Γ\Gamma.Comment: 36 page

    The Maine Annex, vol. 1, no. 2

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    The Maine Annex, published by the students of the University of Maine at the Brunswick Campus, was launched January 10, 1947. Editors introduced the publication as the product of a group of progressive students attending the Brunswick Campus. The goal of the publication, according to editors, was to tell the story of our life on this campus. The four-page, tabloid-sized paper included display advertising from area businesses. Stories in this issue of The Maine Annex are news items of interest to World War II Veterans, including international news from Europe and tips regarding the filing of federal paperwork to secure veterans benefits

    The Maine Annex, vol. 1, no. 3

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    The Maine Annex, published by the students of the University of Maine at the Brunswick Campus, was launched January 10, 1947. Editors introduced the publication as the product of a group of progressive students attending the Brunswick Campus. The goal of the publication, according to editors, was to tell the story of our life on this campus. The four-page, tabloid-sized paper included display advertising from area businesses. Among front page headlines is: Pres. Hauck Addresses Maine Annex Students. President Hauck States That Education Is Now Recognized As One Of The Prime Factors In Building World Peace

    Thermodynamics of volume collapse transitions in cerium and related compounds

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    We present a non-linear elastic model of a coherent transition with discontinuous volume change in an isotropic solid. The model reproduces the anomalous thermodynamics typical of coherent equilibrium including intrinsic hysteresis (for a pressure driven experiment) and a negative bulk modulus. The novelty of the model is that the statistical mechanics solution can be easily worked out. We find that coherency leads to an infinite-range density--density interaction, which drives classical critical behavior. The pressure width of the hysteresis loop shrinks with increasing temperature, ending at a critical point at a temperature related to the shear modulus. The bulk modulus softens with a 1/2 exponent at the transition even far from the critical point. Many well known features of the phase diagram of Ce and related systems are explained by the model.Comment: Acta Materialia, in pres
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