Free Core Nutation observed by VLBI

The signature of free core nutation (FCN) is found in the motion of the celestial intermediate pole in the celestial reference frame and in the resonance behaviour of the frequency-dependent Earth tidal displacement in its diurnal band. We focus on estimation of the FCN parameters, i.e. the period and amplitude. We run several global adjustments of 27 years of very long baseline interferometry (VLBI) data (1984.0 - 2011.0) to determine the FCN period from partial derivatives of the VLBI observables with respect to the FCN as contained in the nutation of the celestial intermediate pole and in the solid Earth tidal displacement in the diurnal band. Finally, we estimate the FCN period by a global adjustment from both phenomena simultaneously, which has not been done before. We find that our estimate of the FCN period of -431.18 +/- 0.10 sidereal days slightly deviates from the conventional value of -431.39 sidereal days. Additionally, we present our empirical model of the FCN with variable amplitude and phase compatible with the estimated period.Comment: 5 page

Tidal Love and Shida numbers estimated by geodetic VLBI

AbstractFrequency-dependent Love and Shida numbers, which characterize the Earth response to the tidal forces, were estimated in a global adjustment of all suitable geodetic Very Long Baseline Interferometry (VLBI) sessions from 1984.0 to 2011.0. Several solutions were carried out to determine the Love and Shida numbers for the tidal constituents at periods in the diurnal band and in the long-period band in addition to values of the Love and Shida numbers common for all tides of degree two. Adding up all twelve diurnal tidal waves that were estimated, the total differences in displacement with respect to the theoretical conventional values of the Love and Shida numbers calculated from an Earth model reach 1.73±0.29mm in radial direction and 1.15±0.15mm in the transverse plane. The difference in the radial deformation following from the estimates of the zonal Love numbers is largest for the semi-annual tide Ssa with 1.07±0.19mm

Evaluation of the impact of atmospheric pressure loading modeling on GNSS data analysis

In recent years, several studies have demonstrated the sensitivity of Global Navigation Satellite System (GNSS) station time series to displacements caused by atmospheric pressure loading (APL). Different methods to take the APL effect into account are used in these studies: applying the corrections from a geophysical model on weekly mean estimates of station coordinates, using observation-level corrections during data analysis, or solving for regression factors between the station displacement and the local pressure. The Center for Orbit Determination in Europe (CODE) is one of the global analysis centers of the International GNSS Service (IGS). The current quality of the IGS products urgently asks to consider this effect in the regular processing scheme. However, the resulting requirements for an APL model are demanding with respect to quality, latency, and—regarding the reprocessing activities—availability over a long time interval (at least from 1994 onward). The APL model of Petrov and Boy (J Geophys Res 109:B03405, 2004) is widely used within the VLBI community and is evaluated in this study with respect to these criteria. The reprocessing effort of CODE provides the basis for validating the APL model. The data set is used to solve for scaling factors for each station to evaluate the geophysical atmospheric non-tidal loading model. A consistent long-term validation of the model over 15years, from 1994 to 2008, is thus possible. The time series of 15years allows to study seasonal variations of the scaling factors using the dense GNSS tracking network of the IGS. By interpreting the scaling factors for the stations of the IGS network, the model by (2004) is shown to meet the expectations concerning the order of magnitude of the effect at individual stations within the uncertainty given by the GNSS data processing and within the limitations due to the model itself. The repeatability of station coordinates improves by 20% when applying the effect directly on the data analysis and by 10% when applying a post-processing correction to the resulting weekly coordinates compared with a solution without taking APL into accoun

High-frequency earth rotation variations deduced from altimetry-based ocean tides

A model of diurnal and semi-diurnal variations in Earth rotation parameters (ERP) is constructed based on altimetry-measured tidal heights from a multi-mission empirical ocean tide solution. Barotropic currents contributing to relative angular momentum changes are estimated for nine major tides in a global inversion algorithm that solves the two-dimensional momentum equations on a regular 0.5^\circ grid with a heavily weighted continuity constraint. The influence of 19 minor tides is accounted for by linear admittance interpolation of ocean tidal angular momentum, although the assumption of smooth admittance variations with frequency appears to be a doubtful concept for semi-diurnal mass terms in particular. A validation of the newly derived model based on post-fit corrections to polar motion and universal time (\Delta UT1) from the analysis of Very Long Baseline Interferometry (VLBI) observations shows a variance reduction for semi-diurnal \Delta UT1 residuals that is significant at the 0.05 level with respect to the conventional ERP model. Improvements are also evident for the explicitly modeled K_1, Q_1, and K_2 tides in individual ERP components, but large residuals of more than 15 \upmu as remain at the principal lunar frequencies of O_1 and M_2. We attribute these shortcomings to uncertainties in the inverted relative angular momentum changes and, to a minor extent, to violation of mass conservation in the empirical ocean tide solution. Further dedicated hydrodynamic modeling efforts of these anomalous constituents are required to meet the accuracy standards of modern space geodesy

Erosion oder/ und Umbruch des Religiösen? Die Herausforderung von Markt und Medien für die Kirchen

'Der Artikel fragt nach den Veränderungen von Religion in der (post-)modernen Markt- und Mediengesellschaft. Er stellt fest, dass sich Religion von traditionellen institutionellen Bindungen löst und in ihren Ausprägungen pluralistischer wird. Zugleich wird Religion 'funktionalisiert' - das bedeutet, dass sie nicht mehr von Bezügen ausgeht, die die Welt transzendieren, sondern sich neu organisiert, indem 'Nutzenaspekte' im Vordergrund stehen. Dabei übernehmen Medien religiöse Funktionen. Mit Blick auf das Fernsehen und am konkreten Beispiel der Sendung 'Traumhochzeit' lässt sich festhalten, dass dieses einerseits ursprünglich in den Kirchen beheimatete Rituale und ihre 'Stabilisierungsfunktion' aufgreift, andererseits mit einer medialen 'Transzendenz' reale Wirklichkeit stützt und bearbeitet. Für die Kirchen entsteht durch eine derartige 'Medienreligion' eine neue Konkurrenzsituation mit der Gefahr, dass spezifische christliche Inhalte verloren gehen. Der Beitrag kommt zum Schluss, dass Kirchen einerseits das Phänomen der 'Medienreligion' ernst nehmen und in ihrer Arbeit mit Menschen dort ansetzen müssen; andererseits ist aber in einer theologischen Perspektive der Verweis auf einen Gott erforderlich, welcher der menschlichen Verfügbarkeit entzogen ist.' (Autorenreferat)'The article inquires about the change of 'religion' in a (post-)modern society of market and media. Religion loses traditional institutional ties and becomes more pluralistic. At the same time, - religion increasingly 'functionalises' - it no longer focuses on the transcendental perspective, but is primarily organized according to utility aspects. For example, referring to television, especially the TV show 'Traumhochzeit', the argument can be stressed that television, on the one hand, supplies functions of stability that are based on rituals, originally being used by the Christian churches. On the other hand, 'media transcendence' also creates reality. Churches face now a new competition by 'media religion', involving the risk that the specific Christian content gets lost. The authors conclude that churches not only should seriously integrate this 'media religion' in their practical work with people, but also, from a theological viewpoint, still must refer to a God, who is not accessible to human availability.' (author's abstract)

Make Yourselves Scarce: The Effect of Demographic Change on the Relative Wages and Employment Rates of Experienced Workers

We show that rising supply of experience not only reduces experienced workers’relative wages but also their relative labor market participation. From a theoretical model we derive predictions which we quasi-experimentally investigate, using variation across U.S. local labor markets (LLMs) over the last decades and instrumenting experience supply by the LLMs' age structures a decade earlier. We find that aging substantially reduces experienced workers' relative wages and employment rates, and also their labor market participation rates. Our results imply that the effect of demographic change on labor markets might be more severe than previously recognized, as it reaches beyond wages

Structural manipulations of a shelter resource reveal underlying preference functions in a shell-dwelling cichlid fish

Many animals can modify the environments in which they live, thereby changing the selection pressures they experience. A common example of such niche construction is the use, creation or modification of environmental resources for use as nests or shelters. Because these resources often have correlated structural elements, it can be difficult to disentangle the relative contribution of these elements to resource choice, and the preference functions underlying niche-construction behaviour remain hidden. Here, we present an experimental paradigm that uses 3D scanning, modelling and printing to create replicas of structures that differ with respect to key structural attributes. We show that a niche-constructing, shell-dwelling cichlid fish,; Neolamprologus multifasciatus; , has strong open-ended preference functions for exaggerated shell replicas. Fish preferred shells that were fully intact and either enlarged, lengthened or had widened apertures. Shell intactness was the most important structural attribute, followed by shell length, then aperture width. We disentangle the relative roles of different shell attributes, which are tightly correlated in the wild, but nevertheless differentially influence shelter choice and therefore niche construction in this species. We highlight the broad utility of our approach when compared with more traditional methods (e.g. two-choice tasks) for studying animal decision-making in a range of contexts