Experimental Flow Investigation of a Truncated Ideal Contour Nozzle

Various tests showed a significant side load peak for low nozzle pressure ratios during engine start-up and shut down phase. DLR Lampoldshausen carried out tests to examine the flow field in a truncated ideal contour nozzle for low NPR. For NPR20 a slight concave shaped Mach disk was found. Its curvature is limited to the centre and its height trend correlates with measured side loads. A concave shaped Mach disk being responsible for re-attached flows at low NPR could be excluded. The experiments were accompanied by numerical simulations of the flow field on various pressure ratios with regards on the shock pattern. The predicted Mach disk shape compares well with the experiments

QCD thermodynamics with effective models

In this talk we extend the Polyakov-quark-meson model to N_f=2+1 quark flavors and study its bulk thermodynamics at finite temperatures in mean-field approximation. Three different Polyakov-loop potentials are considered. Our findings are confronted to recent QCD lattice simulations of the RBC-Bielefeld and HotQCD collaborations. Furthermore, the finite chemical potential expansion of the quark-number susceptibility in a Taylor series around vanishing chemical potential is analyzed. By means of a novel algorithmic differentiation technique, we have calculated Taylor coefficients up to 24th order in the model for the first time. This allows the systematic study of convergence properties of the Taylor series.Comment: [references added]; 10 pages, 5 figures, talk given at the workshop CPOD 2009, June 08 - 12, BNL, US

On the efficient computation of high-order derivatives for implicitly defined functions

Scientific studies often require the precise calculation of derivatives. In many cases an analytical calculation is not feasible and one resorts to evaluating derivatives numerically. These are error-prone, especially for higher-order derivatives. A technique based on algorithmic differentiation is presented which allows for a precise calculation of higher-order derivatives. The method can be widely applied even for the case of only numerically solvable, implicit dependencies which totally hamper a semi-analytical calculation of the derivatives. As a demonstration the method is applied to a quantum field theoretical physical model. The results are compared with standard numerical derivative methods.Comment: 11 pages, 4 figures, to appear in Comput. Phys. Commu

QCD Thermodynamics: Confronting the Polyakov-Quark-Meson Model with Lattice QCD

NJL-type effective models represent a low-energy realization of QCD and incorporate pertinent aspects such as chiral symmetry and its spontaneous breaking, the center symmetry in the heavy-quark limit as well as the axial anomaly. One such model, the Polyakov-quark-meson model for three light quark flavors, is introduced in order to study the phase structure of strongly-interacting matter. With recent high-statistics lattice QCD simulations of the finite-temperature equation of state, a detailed comparison with model results becomes accessible. Such comparisons allow to estimate volume and truncation effects of quantities, obtained on the lattice and provide possible lattice extrapolation procedures to finite chemical potential which are important to locate a critical endpoint in the QCD phase diagram.Comment: 10 pages, 4 figures, contributed to the proceedings of the EMMI Workshop and XXVI Max Born Symposium at 09th-11th of July 2009 in Wroclaw, Polan

On the links between employment, partnership quality, and the desire to have a first child

We examine the impact of precarious work (low income and job security satisfaction) on the intention to have a first child. We consider a direct and an indirect effect; the latter is mediated by partners’ conflict behaviour, conflict level, and partnership quality. We assume that a satisfactory partnership is positively associated with the intention to have a first child. The analyses are based on a subsample of the German Generations and Gender Survey. For men we found a direct effect of income and an indirect effect of job security satisfaction on childbearing intentions, whereas for women no direct and only a weak indirect impact of precarious work could be observed.employment, fertility, partnerships

Comparing word and syllable prominence rated by naïve listeners

Prominence has been widely studied on the word level and the syllable level. An extensive study comparing the two approaches is missing in the literature. This study investigates how word and syllable prominence relate to each other in German. We find that perceptual ratings based on the word level are more extreme than those based on the syllable level. The correlations between word prominence and acoustic features are greater than the correlations between syllable prominence and acoustic features

Obtaining prominence judgments from naïve listeners – Influence of rating scales, linguistic levels and normalisation

A frequently replicated finding is that higher frequency words tend to be shorter and contain more strongly reduced vowels. However, little is known about potential differences in the articulatory gestures for high vs. low frequency words. The present study made use of electromagnetic articulography to investigate the production of two German vowels, [i] and [a], embedded in high and low frequency words. We found that word frequency differently affected the production of [i] and [a] at the temporal as well as the gestural level. Higher frequency of use predicted greater acoustic durations for long vowels; reduced durations for short vowels; articulatory trajectories with greater tongue height for [i] and more pronounced downward articulatory trajectories for [a]. These results show that the phonological contrast between short and long vowels is learned better with experience, and challenge both the Smooth Signal Redundancy Hypothesis and current theories of German phonology

Sedimentary and tectonic evolution of ancient Lake Ohrid (Macedonia/Albania)

Lake Ohrid (Macedonia / Albania) is probably the oldest lake in Europe (2-5 Ma), and is considered an important sedimentary archive to study the evolution of a graben system over several million years. Multichannel seismic profiles were acquired in 2007 and 2008 showing that the lake can be divided into two main parts, the slope areas and a large, deep central basin. The basin is bordered by the major eastern and western graben fault, additional faults were identifi ed in the northern part of the lake. These faults are active, as we can trace them from the basement up to the lake floor. Clinoforms mainly found in the southern part of the lake indicate that the Lake has undergone major lake level fluctuations. The central basin shows widespread areas with thick, undisturbed sedimentary successions. No indications for a dry lake are found in this part of the lake, hence, offering the possibility to recover long, continuous archives for the entire lifetime of Lake Ohrid in the frame of the proposed SCOPSCO(Scientific Collaboration On Past Speciation Conditions in Lake Ohrid)-ICDP(International Continental Drilling Program) campaign. Five primary drilling locations have been chosen as ICDP sites. One 680 m long record in the central part will provide substantial information on age and origin of the lake, as well as a complete record of environmental history (incl. e.g. tephra deposition, evolutionary changes and their relation to geological events). Furthermore, four additional drill sites closer to the shore of the lake will provide information on major changes of the hydrological regime, the age of ancient foresets, lake level changes, the tectonic activity, and mass movements. The drilling proposal is approved by ICDP and will be realized in summer 2011 or 2012

The effect of priming on the correlations between prominence ratings and acoustic features

Arnold D, Wagner P, Möbius B. The effect of priming on the correlations between prominence ratings and acoustic features. In: Prosodic Prominence: Perceptual and Automatic Identification (Speech Prosody 2010 Workshop). 2010: W1.02.In previous research we showed that the priming paradigm can be used to significantly alter the prominence ratings of subjects. In that study we only looked at the changes in the subjects’ ratings. In the present study, we analyzed the acoustic parameters of the stimuli used in the priming study and investigated the correlation between prominence ratings and acoustic parameters. The results show that priming has a significant effect on these correlations. The contribution of acoustic features on perceived prominence was found to depend on the prominence pattern. If a dominantly prominent syllable is present in a given utterance, f0 and intensity contribute most to the perceived prominence, while duration contributes most when no syllable is dominantly prominent. Index Terms: syllable, prominence, priming, acoustic correlate