5,716 research outputs found

    Sprayer-Testing - Electronic analysis of the test reports

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    contribution to optional evening activities - presentation

    Economic Comparison of the Farm, Nutrition, and Bioenergy Act (H.R. 2419) to Fairness in Farm and Food Policy Amendment to H.R. 2419

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    The House Agriculture Committee unanimously passed their farm bill, “Farm, Nutrition and Bioenergy Act of 2007” (H.R. 2419). An amendment, “Fairness in Farm and Food Policy,” H.R. 2419 was announced by Ron Kind (D-WI). The purpose of this Briefing Report is to compare the likely economic impacts of H.R. 2419 and the FFFP Amendment on representative crop, dairy, and cattle farms.Agricultural and Food Policy,

    On the phase structure and thermodynamics of QCD

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    We discuss the phase structure and thermodynamics of QCD by means of dynamical chiral effective models. Quark and meson fluctuations are included via the functional renormalization group. We study the influence of confinement in addition to the impact of fluctuations by comparing the results of the chiral models to their Polyakov-loop extended versions. Furthermore, we discuss the mass sensitivity of the phase structure and thermodynamics and find interesting modifications close to the chiral limit.Comment: 13 pages, 11 figures; Appendix added; published versio

    D-brane Categories for Orientifolds -- The Landau-Ginzburg Case

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    We construct and classify categories of D-branes in orientifolds based on Landau-Ginzburg models and their orbifolds. Consistency of the worldsheet parity action on the matrix factorizations plays the key role. This provides all the requisite data for an orientifold construction after embedding in string theory. One of our main results is a computation of topological field theory correlators on unoriented worldsheets, generalizing the formulas of Vafa and Kapustin-Li for oriented worldsheets, as well as the extension of these results to orbifolds. We also find a doubling of Knoerrer periodicity in the orientifold context.Comment: 45 pages, 6 figure

    Boundary states, matrix factorisations and correlation functions for the E-models

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    The open string spectra of the B-type D-branes of the N=2 E-models are calculated. Using these results we match the boundary states to the matrix factorisations of the corresponding Landau-Ginzburg models. The identification allows us to calculate specific terms in the effective brane superpotential of E_6 using conformal field theory methods, thereby enabling us to test results recently obtained in this context.Comment: 20 pages, no figure

    Exploring the Phase Structure and Thermodynamics of QCD

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    We put forward a Polyakov-loop extended quark meson model, where matter as well as glue fluctuations are taken into account, cf. [1]. The latter are included via a Polyakov-loop potential. Usually such a glue potential is based on Yang-Mills lattice data only. We show that a parametrisation of unquenching effects as proposed in [2], together with the inclusion of fluctuations via the functional renormalisation group [3,4], accounts for the relevant dynamics. This is demonstrated by a comparison of order parameters and thermodynamic observables to recent lattice results at vanishing chemical potential, where we find very good agreement.Comment: 11 pages, 2 figures, contribution to "QCD-TNT-III: From quarks and gluons to hadronic matter: A bridge too far?", ECT*, Trento (Italy), September 2-6, 201

    Results of the ROTOR-program. I. The long-term photometric variability of classical T Tauri stars

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    We present a unique, homogeneous database of photometric measurements for Classical T Tauri stars extending up to 20 years. The database contains more than 21,000 UBVR observations of 72 CTTs. All the data were collected within the framework of the ROTOR-program at Mount Maidanak Observatory (Uzbekistan) and together they constitute the longest homogeneous, accurate record of TTS variability ever assembled. We characterize the long term photometric variations of 49 CTTs with sufficient data to allow a robust statistical analysis and propose an empirical classification scheme. Several patterns of long term photometric variability are identified. The most common pattern, exhibited by a group of 15 stars which includes T Tau itself, consists of low level variability (Delta(V)<=0.4mag) with no significant changes occurring from season to season over many years. A related subgroup of 22 stars exhibits a similar stable long term variability pattern, though with larger amplitudes (up to Delta(V)~1.6 mag). Besides these representative groups, we identify three smaller groups of 3-5 stars each which have distinctive photometric properties. The long term variability of most CTTs is fairly stable and merely reflects shorter term variability due to cold and hot surface spots. Only a small fraction of CTTs undergo significant brightness changes on the long term (months, years), which probably arise from slowly varying circumstellar extinction.Comment: 16 pages, 11 figures. Astron. Astrophys., in pres
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