384 research outputs found

    The International Indian Ocean Expedition

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    The Distinguished Lecture Series 1964-1965, sponsored by Science Bureau, Washington Board of Trade, presented at Georgetown University, January 27, 1965Tonight, I want to tell you about another great oceanographic expedition; one which has been done in the tradition of the past great expeditions, but with all the tools available to modern oceanography. This is the International Indian Ocean Expedition, which constitutes the cooperative efforts of some 27 nations which have committed over 40 oceanographic research vessels to more than 70 cruises in the Indian Ocean over the past four years. It has been supported in this country by the National Science Foundation, the Navy, the Weather Bureau, the Bureau of Commercial Fisheries and the Coast and Geodetic Survey. Officially, the International Indian Ocean Expedition is being completed during the current year but it will be many years before all the data have been thoroughly analyzed and evaluated

    Phase separation and electron pairing in repulsive Hubbard clusters

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    Exact thermal studies of small (4-site, 5-site and 8-site) Hubbard clusters with local electron repulsion yield intriguing insight into phase separation, charge-spin separation, pseudogaps, condensation, in particular, pairing fluctuations away from half filling (near optimal doping). These exact calculations, carried out in canonical (i.e. for fixed electron number N) and grand canonical (i.e. fixed chemical potential μ\mu) ensembles, monitoring variations in temperature T and magnetic field h, show rich phase diagrams in a T-μ\mu space consisting of pairing fluctuations and signatures of condensation. These electron pairing instabilities are seen when the onsite Coulomb interaction U is smaller than a critical value Uc_c(T) and they point to a possible electron pairing mechanism. The specific heat, magnetization, charge pairing and spin pairing provide strong support for the existence of competing (paired and unpaired) phases near optimal doping in these clusters as observed in recent experiments in doped La2x_{2-x}Srx_xCuO4+y_{4+y} high Tc_c superconductors.Comment: 5 pages, 5 figure

    A Maximum Entropy Method of Obtaining Thermodynamic Properties from Quantum Monte Carlo Simulations

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    We describe a novel method to obtain thermodynamic properties of quantum systems using Baysian Inference -- Maximum Entropy techniques. The method is applicable to energy values sampled at a discrete set of temperatures from Quantum Monte Carlo Simulations. The internal energy and the specific heat of the system are easily obtained as are errorbars on these quantities. The entropy and the free energy are also obtainable. No assumptions as to the specific functional form of the energy are made. The use of a priori information, such as a sum rule on the entropy, is built into the method. As a non-trivial example of the method, we obtain the specific heat of the three-dimensional Periodic Anderson Model.Comment: 8 pages, 3 figure

    Studies on the Mating Behavior of the House Fly, Musca Domestica L.

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    Author Institution: Entomology Research Division, Agric, Res. Serv., U.S.D.A. Gainesville, Fla

    Hepatocellular carcinoma: Review of disease and tumor biomarkers.

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    © The Author(s) 2016.Hepatocellular carcinoma (HCC) is a common malignancy and now the second commonest global cause of cancer death. HCC tumorigenesis is relatively silent and patients experience late symptomatic presentation. As the option for curative treatments is limited to early stage cancers, diagnosis in non-symptomatic individuals is crucial. International guidelines advise regular surveillance of high-risk populations but the current tools lack sufficient sensitivity for early stage tumors on the background of a cirrhotic nodular liver. A number of novel biomarkers have now been suggested in the literature, which may reinforce the current surveillance methods. In addition, recent metabonomic and proteomic discoveries have established specific metabolite expressions in HCC, according to Warburgs phenomenon of altered energy metabolism. With clinical validation, a simple and non-invasive test from the serum or urine may be performed to diagnose HCC, particularly benefiting low resource regions where the burden of HCC is highest

    Competition Between Antiferromagnetic Order and Spin-Liquid Behavior in the Two-Dimensional Periodic Anderson Model at Half-Filling

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    We study the two-dimensional periodic Anderson model at half-filling using quantum Monte Carlo (QMC) techniques. The ground state undergoes a magnetic order-disorder transition as a function of the effective exchange coupling between the conduction and localized bands. Low-lying spin and charge excitations are determined using the maximum entropy method to analytically continue the QMC data. At finite temperature we find a competition between the Kondo effect and antiferromagnetic order which develops in the localized band through Ruderman-Kittel-Kasuya-Yosida interactions.Comment: Revtex 3.0, 10 pages + 5 figures, UCSBTH-94-2
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