Influence of base modifications on in-flight base drag in the presence of jet exhaust for Mach numbers from 0.7 to 1.5

The use of external modifications in the base region to reduce the base drag of a blunt-base body in the presence of jet engine exhaust was investigated in flight. Base pressure data were obtained for the following configurations: (1) blunt base; (2) blunt base modified with splitter plate; and (3) blunt base modified with two variations of a vented cavity. Reynolds number based on the length of the aircraft ranged from 1.2 to 3.1 x 10 to the 8th. Mach number M ranges were 0.71 less than or = M less than or = 0.95 and 1.10 less than or = M less than or = 1.51. The data were analyzed using the blunt base for a reference, or baseline condition. For 1.10 less than or = M less than or = 1.51, the reduction in base drag coefficient provided by the vented cavity configuration ranged from 0.07 to 0.05. These increments in base drag coefficient at M = 1.31 and 1.51 result in base drag reductions of 27 and 24 percent, respectively, when compared to the blunt base drag. For M less than 1, the drag increment between the blunt base and the modification is not significant

Beyond Rainbow-Ladder in bound state equations

In this work we devise a new method to study quark anti-quark interactions beyond simple ladder-exchange that yield massless pions in the chiral limit. The method is based on the requirement to have a representation of the quark-gluon vertex that is explicitly given in terms of quark dressings functions. We outline a general procedure to generate the Bethe-Salpeter kernel for a given vertex representation. Our method allows not only the identification of the mesons' masses but also the extraction of their Bethe-Salpeter wave functions exposing their internal structure. We exemplify our method with vertex models that are of phenomenological interest.Comment: 13 pages, 6 figures; v2: typos corrected, colors improve

A fresh look at hadronic light-by-light scattering in the muon g-2 with the Dyson-Schwinger approach

We present first results for the hadronic light-by-light scattering contribution to the anomalous magnetic moment of the muon a_{\mu} in the framework of Dyson-Schwinger and Bethe-Salpeter equations. We determine the quark loop and pseudoscalar ({\pi}^0, {\eta}, {\eta}') meson exchange diagram using a phenomenological model for the combined strength of the gluon propagator and the quark-gluon interaction as the only input. Our result for meson exchange, a_{\mu}^{LBL;PS}=(84 \pm 13) x 10^{-11}, is commensurate with previous calculations. However, our number for the quark loop contribution, a_{\mu}^{LBL;quarkloop} = (107 \pm 2 \pm 46) x 10^{-11}, is significantly larger due to dressing effects in the quark propagator and the quark-photon vertex. Taken at face value, this then leads to a revised estimate of the total a_{\mu}=116 591 865.0(96.6) x 10^{-11}, which reduces the difference between theory and experiment to about 1.9 {\sigma}.Comment: 5 pages, 7 figures, v2: title slightly changed, minor corrections, version accepted by EP

Europa driftet auseinander: Ist dies das Ende der realwirtschaftlichen Konvergenz?

Die europäische Integration, die in den 1950er Jahren einsetzte, zielt auch darauf ab, die Wirtschaftskraft der teilnehmenden Volkswirtschaften anzugleichen. In den vergangenen sechs Dekaden zeigte sich insgesamt eine absolute und relative Erhöhung der Pro-Kopf-Einkommen der zuvor ärmeren Länder. Der Konvergenzprozess verlief in den einzelnen Ländern jedoch nicht gleichmäßig und auch nicht durchgehend. Vor allem infolge der Wirtschaftskrise, die im Jahr 2008 einsetzte, kehrte sich die Konvergenz in eine Divergenz um. Die südeuropäischen Krisenländer fielen zuletzt deutlich zurück. Auch in der nahen Zukunft ist nicht mit einer wieder einsetzenden Konvergenz zu rechnen. Wirtschaftspolitische Reformen in den einzelnen Ländern sind notwendig, um Europa wirtschaftlich wieder näher zusammenzuführen. Auch die EU kann mit ihren Instrumenten einen wichtigen Beitrag leisten

Flight tests of external modifications used to reduce blunt base drag

The effectiveness of a trailing disk (the trapped vortex concept) in reducing the blunt base drag of an 8-in diameter body of revolution was studied from measurements made both in flight and in full-scale wind-tunnel tests. The experiment demonstrated the significant base drag reduction capability of the trailing disk to Mach 0.93. The maximum base drag reduction obtained from a cavity tested on the flight body of revolution was not significant. The effectiveness of a splitter plate and a vented-wall cavity in reducing the base drag of a quasi-two-dimensional fuselage closure was studied from base pressure measurements made in flight. The fuselage closure was between the two engines of the F-111 airplane; therefore, the base pressures were in the presence of jet engine exhaust. For Mach numbers from 1.10 to 1.51, significant base drag reduction was provided by the vented-wall cavity configuration. The splitter plate was not considered effective in reducing base drag at any Mach number tested

Sticky Prices vs. Sticky Information – A Cross-Country Study of Inflation Dynamics

This paper empirically compares sticky-price and sticky-information Phillips curves considering inflation dynamics in six countries (US, UK, Germany, France, Canada, and Japan). We evaluate the models‘ abilities to match empirical second moments of inflation. Under baseline calibrations, the two models perform similarly in almost all countries. Under estimated parametrizations, sticky information performs better in France while sticky prices dominate in the UK and Germany. Sticky prices match unconditional moments of inflation dynamics better while sticky information is more successful in matching co-movement of inflation with demand. Both models‘ performances worsen where inflation dynamics diff er from the US benchmark.Phillips curve; sticky information; sticky prices