Astronomical Tests of the Einstein Equivalence Principle

The Einstein equivalence principle is certainly a key element in the development of new enhanced theories of gravity. Although being an important building block in Einstein's general relativity, theoretically predicted violations of its validity are a main feature in alternative, nonmetric gravitation theories if they are able to incorporate quantum mechanical principles. We have investigated the metric-affine gauge theory of gravity which predict that a gravitational field singles out an orthogonal pair of polarization states of light that propagate with different phase velocities. This gravity-induced birefringence implies that propagation through a gravitational field can alter the polarization of light and, so, violates the Einstein equivalence principle. We use solar and white dwarf polarimetric data to constrain birefringence induced by the gravitational field of these objects and set limits on coupling constants required by such theories.Comment: PhD thesis, written at the Max-Planck-Institute for Aeronomy, Germany. A high resolution postscript version can be found at http://archiv.ub.uni-bielefeld.de/disshabi/2002/0106.p

Gravity-induced birefringence within the framework of Poincare gauge theory

Gauge theories of gravity provide an elegant and promising extension of general relativity. In this paper we show that the Poincar\'e gauge theory exhibits gravity-induced birefringence under the assumption of a specific gauge invariant nonminimal coupling between torsion and Maxwell's field. Furthermore we give for the first time an explicit expression for the induced phaseshift between two orthogonal polarization modes within the Poincar\'e framework. Since such a phaseshift can lead to a depolarization of light emitted from an extended source this effect is, in principle, observable. We use white dwarf polarimetric data to constrain the essential coupling constant responsible for this effect.Comment: 12 pages, accepted for publication by Physical Review

Constraining Gravitational Theories by Observing Magnetic White Dwarfs

Under the assumption of a specific nonminimal coupling of torsion to Under the assumption of a specific nonminimal coupling of torsion to electromagnetism, spacetime is birefringent in the presence of a gravitational field leading to depolarization of light emitted from extended astrophysical sources. We use polarimetric data of the magnetic white dwarf RE J0317-853 to set for the very first time constraints on the essential coupling constant for this effect, giving k^2 <22 m^2. electromagnetism, spacetime is birefringent in the presence of a gravitational field leading to depolarization of light emitted from extended astrophysical sources. We use polarimetric data of the magnetic white dwarf RE J0317-853 to set for the very first time constraints on the essential coupling constant for this effect, giving k^2 <22 m^2.Comment: 4 pages, 1 Figure, to appear in the proceedings of the 14th European Workshop on White Dwarfs, eds. D. Koester and S. Moehler, ASP Conf. Serie

An astronomical search for evidence of new physics: Limits on gravity-induced birefringence from the magnetic white dwarf RE J0317-853

The coupling of the electromagnetic field directly with gravitational gauge fields leads to new physical effects that can be tested using astronomical data. Here we consider a particular case for closer scrutiny, a specific nonminimal coupling of torsion to electromagnetism, which enters into a metric-affine geometry of space-time. We show that under the assumption of this nonminimal coupling, spacetime is birefringent in the presence of such a gravitational field. This leads to the depolarization of light emitted from extended astrophysical sources. We use polarimetric data of the magnetic white dwarf ${RE J0317-853}$ to set strong constraints on the essential coupling constant for this effect, giving k^2 \lsim (19 {m})^2 .Comment: Statements about Moffat's NGT modified. Accepted for publication in Phys.Rev.

Production of high levels of poly-3-hydroxybutyrate in plastids of Camelina sativa seeds

Poly-3-hydroxybutyrate (PHB) production in plastids of Camelina sativa seeds was investigated by comparing levels of polymer produced upon transformation of plants with five different binary vectors containing combinations of five seed-specific promoters for expression of transgenes. Genes encoding PHB biosynthetic enzymes were modified at the N-terminus to encode a plastid targeting signal. PHB levels of up to 15% of the mature seed weight were measured in single sacrificed T1 seeds with a genetic construct containing the oleosin and glycinin promoters. A more detailed analysis of the PHB production potential of two of the best performing binary vectors in a Camelina line bred for larger seed size yielded lines containing up to 15% polymer in mature T2 seeds. Transmission electron microscopy showed the presence of distinct granules of PHB in the seeds. PHB production had varying effects on germination, emergence and survival of seedlings. Once true leaves formed, plants grew normally and were able to set seeds. PHB synthesis lowered the total oil but not the protein content of engineered seeds. A change in the oil fatty acid profile was also observed. High molecular weight polymer was produced with weight-averaged molecular weights varying between 600 000 and 1 500 000, depending on the line. Select lines were advanced to later generations yielding a line with 13.7% PHB in T4 seeds. The levels of polymer produced in this study are the highest reported to date in a seed and are an important step forward for commercializing an oilseed-based platform for PHB production

Volkswirtschaftliche Bedeutung Olympische Winterspiele Graubünden 2022

Der Verein Graubünden 2022 beabsichtigte, sich als offizielle Kandidatur der Schweiz für die Olympischen Winterspiele 2022 zu bewerben. Im Hinblick auf die politische Diskussion und das Kandidaturdossier zur Bewerbung wurde das Forschungsnetzwerk Rütter Soceco, Eidgenössische Hochschule für Sport Magglingen EHSM und Institut für Tourismuswirtschaft ITW Hochschule Luzern beauftragt, die potenziellen wirtschaftlichen Wirkungen der Olympischen Winterspiele auf die Austragungsregion und die gesamte Schweiz zu analysieren. Die Studie gliedert sich in zwei Hauptteile und eine Zusammenfassung der Erkenntnisse. Der erste Teil des Berichts, der am 30. Oktober 2012 publiziert wurde, fokussiert auf den wirtschaftlichen Primärimpuls (Budgets und touristische Ausgaben) und die damit verbundenen volkswirtschaftlichen Wirkungen von Graubünden 2022. Er weist die direkten und indirekten Wertschöpfungs- und Beschäftigungswirkungen sowie die Steuerwirkungen im Kanton Graubünden und in der übrigen Schweiz aus, unter besonderer Berücksichtigung der Wirkungen auf den Tourismus. Für den Gesamtbericht wurden die Wirkungen für die drei Regionen Davos/Kloster, Oberengadin und „“übrige Region““ regionalisiert. Der zweite Teil der Studie zeigt die potenziellen langfristigen Wirkungen (Legacy) von Graubünden 2022 qualitativ auf. Dabei werden acht Themen unterschieden und die wichtigsten mit der Durchführung verbundenen Risiken dargestellt. Wie die Potenziale ausgeschöpft werden, wird wesentlich davon abhängen, dass die Legacyaspekte frühzeitig in die Planung der OWS Graubünden 22 einbezogen werden

The effect of aluminium on twinning in binary alpha-titanium

The deformation mechanisms of binary Ti–Al model alloys (0–13.1 at.% Aluminium) have been investigated with respect to the twinning activity using in-situ loading in combination with neutron diffraction as well as detailed post mortem electron backscatter diffraction analysis. A consistent starting grain size and texture was generated for all alloys promoting tensile twinning during compression testing. Long-wavelength neutron diffraction and selected area diffraction transmission electron microscopy analysis were carried out to detect evidence of Aluminium ordering and Ti3Al formation.It was found that raising the Aluminium content in Titanium does first slightly enhance twinning, with {10View the MathML source2} tensile twinning being by far the dominant type, while the critical residual intergranular strains for twin initiation decreases. This suggests that either the lowering of stacking fault energy by Aluminium or its solute solution strengthening effect are important factors. At around 7 at.% Aluminium a turning point in twinning activity was noticed and a further increase in Aluminium did result in a dramatic loss of twinning activity particularly when the material had been exposed to an additional low temperature age. The dramatic decrease of twinning activity is strongly correlated with increasing evidence of short range ordering and also early signs of Ti3Al-formation in case of the highest Aluminium content. In addition, electron backscatter diffraction analysis revealed that the formation of Aluminium ordered zones do severely hinder growth of twin boundaries

On the effectiveness of private transnational governance regimes - evaluating corporate sustainability reporting according to the Global Reporting Initiative

The increasing involvement of multinational enterprises (MNEs) in global governance has been both applauded for its potential to make governance more effective and criticized for lacking democratic legitimization. Hence we investigate the effectiveness of one transnational governance regime, corporate sustainability reporting according to the Global Reporting Initiative (GRI). We found that the GRI has been successful in terms of output effectiveness by promoting the dissemination of sustainability reporting, in particular among Asian and South American companies. However, the outcome effectiveness of the GRI is limited as reporting showed a rather uniform content across countries and sectors which does not reflect materiality considerations. As GRI reporting does not seem to have facilitated greater company–stakeholder interaction, its impact effectiveness is likely to be limited too

Managing Imbalanced Supply Chain Relationships for Sustainability: A Power Perspective

This study adopts a power perspective to investigate sustainable supply chain relationships and specifically uses resource dependence theory (RDT) to critically analyze buyer–supplier–supplier relationships. Empirical evidence is provided, extending the RDT model in this context. The concept of power relationships is explored through a qualitative study of a multinational company and agricultural growers in the UK food industry that work together to implement sustainable practices. We look at multiple triadic relationships involving a large buyer and its small suppliers to investigate how relative power affects the implementation of sustainable supply-management practices. The study highlights that power as dependence is relevant to understanding compliance in sustainable supply chains and to identifying appropriate relationship-management strategies to build more sustainable supply chains. We show the influences of power on how players manage their relationships and how it affects organizational responses to the implementation of sustainability initiatives. Power notably influences the sharing of sustainability-related risks and value between supply chain partners. From a managerial perspective, the study contributes to developing a better understanding of how power can become an effective way to achieve sustainability goals. This paper offers insights into the way in which a large organization works with small and medium size enterprises (SMEs) to implement sustainable practices and shows how power management—that is, the way in which power is used—can support or hinder effective cooperation around sustainability in the supply chain