35,232 research outputs found

    Studying pion effects on the chiral phase transition

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    We investigate the chiral phase transition at finite temperatures and zero chemical potential with Dyson-Schwinger equations. Our truncation for the quark-gluon interaction includes mesonic degrees of freedom, which allows us to study the impact of the pions on the nature of the phase transition. Within the present scheme we find a five percent change of the critical temperature due to the pion backreaction whereas the mean field character of the transition is not changed.Comment: 2 pages, 2 figures, talk given by J.A.M. at the 30th International School of Nuclear Physics, Erice, Sicily from 16 - 24 September 200

    Fluctuation dynamo amplified by intermittent shear bursts in convectively driven magnetohydrodynamic turbulence

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    Intermittent large-scale high-shear flows are found to occur frequently and spontaneously in direct numerical simulations of statistically stationary turbulent Boussinesq magnetohydrodynamic (MHD) convection. The energetic steady-state of the system is sustained by convective driving of the velocity field and small-scale dynamo action. The intermittent emergence of flow structures with strong velocity and magnetic shearing generates magnetic energy at an elevated rate over time-scales longer than the characteristic time of the large-scale convective motion. The resilience of magnetic energy amplification suggests that intermittent shear-bursts are a significant driver of dynamo action in turbulent magnetoconvection

    Are Consumers Indeed Misled? Congruency in Consumers' Attitudes towards Wine Labeling Information versus Revealed Preferences from a Choice Experiment

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    Please Contact Authors for Updated Version before Citingdiscrete choice experiment vs. attitude measurement, food labeling, willingness to pay, consumers, wine, Agricultural and Food Policy, Consumer/Household Economics, Demand and Price Analysis, Food Consumption/Nutrition/Food Safety, Marketing,

    Pairing, Ferromagnetism, and Condensation of a normal spin-1 Bose gas

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    We theoretically study the stability of a normal, spin disordered, homogenous spin-1 Bose gas against ferromagnetism, pairing, and condensation through a Random Phase Approximation which includes exchange (RPA-X). Repulsive spin-independent interactions stabilize the normal state against both ferromagnetism and pairing, and for typical interaction strengths leads to a direct transition from an unordered normal state to a fully ordered single particle condensate. Atoms with much larger spin-dependent interaction may experience a transition to a ferromagnetic normal state or a paired superfluid, but, within the RPA-X, there is no instability towards a normal state with spontaneous nematic order. We analyze the role of the quadratic Zeeman effect and finite system size.Comment: 4 pages, 3 figures, 1 table. Supplementary materials attache

    Matrix partitioning and EOF/principal component analysis of Antarctic Sea ice brightness temperatures

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    A field of measured anomalies of some physical variable relative to their time averages, is partitioned in either the space domain or the time domain. Eigenvectors and corresponding principal components of the smaller dimensioned covariance matrices associated with the partitioned data sets are calculated independently, then joined to approximate the eigenstructure of the larger covariance matrix associated with the unpartitioned data set. The accuracy of the approximation (fraction of the total variance in the field) and the magnitudes of the largest eigenvalues from the partitioned covariance matrices together determine the number of local EOF's and principal components to be joined by any particular level. The space-time distribution of Nimbus-5 ESMR sea ice measurement is analyzed

    Using Best-Worst Scaling to Determine Market Channel Choice by Small Farmers in Indonesia

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    A household survey and a novel Best-Worst scaling method are used to examine the relative importance of various buyer characteristics to small potato farmers in Indonesia. A Latent Class Cluster Analysis is used explore whether producers’ utilities for marketing channels are heterogeneous. For the aggregate sample, the attributes related to the buyer providing immediate cash payment, a price premium and always following through on their commitment to buy their potatoes were the three most important attributes. The results of the Latent Class Cluster Analysis found four unique classes or segments of producers, each with distinct utilities for buyer characteristics and interesting differences socio-demographic characteristics. The largest segment (44%) was relatively similar to the aggregate, placing a high importance on cash payment, price and willingness to negotiate. Two segments, 24% and 16% of producers placed a relatively high importance on the buyer providing access to certified potato seed or finance for purchasing inputs, and another segment placed the highest importance on having a long-term relationship with their buyer. This has interesting implications for traders, particularly traders who are interested in securing a long-term relationship with potato producers – simply being able to provide cash at the time potatoes are delivered and/or a small premium may immediately increase the strength of the relationship.Best-Worst Scaling, Latent Class Cluster Analysis, marketing channel choice, Indonesia, potato farmers, small farmers, Marketing,

    Many-body physics in the radio frequency spectrum of lattice bosons

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    We calculate the radio-frequency spectrum of a trapped cloud of cold bosonic atoms in an optical lattice. Using random phase and local density approximations we produce both trap averaged and spatially resolved spectra, identifying simple features in the spectra that reveal information about both superfluidity and correlations. Our approach is exact in the deep Mott limit and in the deep superfluid when the hopping rates for the two internal spin states are equal. It contains final state interactions, obeys the Ward identities (and the associated conservation laws), and satisfies the ff-sum rule. Motivated by earlier work by Sun, Lannert, and Vishveshwara [Phys. Rev. A \textbf{79}, 043422 (2009)], we also discuss the features which arise in a spin-dependent optical lattice.Comment: 6 pages, 4 figures, 13 subfigure

    Wind-tunnel tests on a 3-dimensional fixed-geometry scramjet inlet at M = 2.30 to 4.60

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    Wind-tunnel tests were conducted on a baseline scramjet inlet model having fixed geometry and swept leading edges at M = 2.30, 2.96, 3.95, and 4.60 in the Langley unitary plan wind tunnel. The unit Reynolds number of the tests was held constant at 6.56 million per meter (2 million per foot). The objectives of the tests were to establish inlet performance and starting characteristics in the lower Mach number range of operation (less than M = 5). Surface pressures obtained on the inlet components are presented, along with the results of the internal flow surveys made at the throat and capture stations of the inlet. Contour plots of the inlet-flow-field parameters such as Mach numbers, pressure recovery, flow capture, local static and total pressure ratios at the survey stations are shown for the test Mach numbers
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