On the nature of prominence emission observed by SDO/AIA

The Prominence-Corona Transition Region (PCTR) plays a key role in the thermal and pressure equilibrium of solar prominences. Our knowledge of this interface is limited and several major issues remain open, including the thermal structure and, in particular, the maximum temperature of the detectable plasma. The high signal-to-noise ratio of images obtained by the Atmospheric Imaging Assembly (AIA) on NASA's Solar Dynamics Observatory clearly show that prominences are often seen in emission in the 171 and 131 bands. We investigate the temperature sensitivity of these AIA bands for prominence observation, in order to infer the temperature content in an effort to explain the emission. Using the CHIANTI atomic database and previously determined prominence differential emission measure distributions, we build synthetic spectra to establish the main emission-line contributors in the AIA bands. We find that the Fe IX line always dominates the 171 band, even in the absence of plasma at > 10^6 K temperatures, while the 131 band is dominated by Fe VIII. We conclude that the PCTR has sufficient plasma emitting at > 4 10^5 K to be detected by AIA.Comment: accepted Ap

Subtraction of test mass angular noise in the LISA Technology Package interferometer

We present recent sensitivity measurements of the LISA Technology Package interferometer with articulated mirrors as test masses, actuated by piezo-electric transducers. The required longitudinal displacement resolution of 9 pm/sqrt[Hz] above 3 mHz has been demonstrated with an angular noise that corresponds to the expected in on-orbit operation. The excess noise contribution of this test mass jitter onto the sensitive displacement readout was completely subtracted by fitting the angular interferometric data streams to the longitudinal displacement measurement. Thus, this cross-coupling constitutes no limitation to the required performance of the LISA Technology Package interferometry.Comment: Applied Physics B - Lasers and Optics (2008

Implications of diverging social and private discount rates for investments in the German power industry: a new case for nuclear energy?

For power-plant investments, utilities rely after liberalisation on private financial markets, which are in general distorted. The (related) split of social and private time-preference rates provides a new reason for a welfare-enhancing policy intervention, complementary to environmental policy (Heinzel and Winkler 2007). This paper quantifies it and studies its relevance for the German power industry around 2015. The distortions remain moderate as compared to other investment subsidies. However, in contrast to environmental policy alone, its additional implementation makes nuclear power the first option even in the nuclear high-cost scenario. Both policies enhance ecological structural change, which end-of-pipe abatement delays. --distorted time preferences,environmental and technology policy,conventional energy technologies

Schumpeter and Georgescu-Roegen on the foundations of an evolutionary analysis: The problem of qualitative change, its methodical implications and analytical treatment

Despite the frequent references to Schumpeter's work, his own encompassing methodological approach as worked out by Shionoya (1997) has hardly been considered. In this paper, it is revisited together with Georgescu-Roegen's contributions to economic methodology in view of (i) their contribution to the foundations of an evolutionary analysis in economics and (ii) their mutual complementarity and differences. Both are centred around the issue of qualitative change and its substantial analysis. Schumpeter's analytical distinction between the levels of subject matter and method and his further distinction between stationary and evolutionary economy on the level of subject matter are shown to be decisive for the structure of his analytical system and the determination of an evolutionary analysis on its basis. It is further shown that Georgescu-Roegen's contributions – his evaluation of the entropy law and his consideration of the implications of qualitative change for economic analysis – follow exactly the general structure of Schumpeter's analytical system which they refine or correct. It is argued that they provided together an encompassing general framework for the analysis of economic evolution necessarily different from, but complementary to modern static and dynamic analysis. However, they did neither state nor solve the general theoretical problem of an evolutionary analysis in their sense. --evolutionary analysis,Georgescu-Roegen,qualitative change,Schumpeter

Analytical description of interference between two misaligned and mismatched complete Gaussian beams

A typical application for laser interferometers is a precision measurement of length changes that result in interferometric phase shifts. Such phase changes are typically predicted numerically, due to the com- plexity of the overlap integral that needs to be solved. In this paper we will derive analytical representations of the interferometric phase and contrast (aka. fringe visibility) for two beam interferometers, both homodyne and heterodyne. The fundamental Gaussian beams can be arbitrarily misaligned and mismatched to each other. A limitation of the analytical result is that both beams must be detected completely, which can experimentally be realized by a sufficiently large single-element photodetector.Comment: 8 pages, 2 figure

Measurement of the absolute wavefront curvature radius in a heterodyne interferometer

We present an analytical derivation of the coupling parameter relating the angle between two interfering beams in a heterodyne interferometer to the differential phase-signals detected by a quadrant photo-diode. This technique, also referred to as Differential Wavefront Sensing (DWS), is commonly used in space-based gravitational wave detectors to determine the attitude of a test-mass in one of the interferometer arms from the quadrant diode signals. Successive approximations to the analytical expression are made to simplify the investigation of parameter dependencies. Motivated by our findings, we propose a new measurement method to accurately determine the absolute wave-front curvature of a single measurement beam. We also investigate the change in coupling parameter when the interferometer "test-mirror" is moved from its nominal position, an effect which mediates the coupling of mirror displacement noise into differential phase-measurements.Comment: double-spaced, 21 pages, 5 figure